Guideline of possible application of slurries in industries demanding micronized materials and valor

Guideline of possible application of slurries in industries Page 1

LIFE Project Number

LIFE10 ENV/ES/000480

Reporting Date

30/03/2012

LIFE+ RECYSLURRY

Valorisation and recycling of slurries produced during

manufacturing stone sector to use as raw materials for

industrial applications

Deliverable 2.1

Deliverable: Guideline of possible application of slurries in industries

demanding micronized materials and valorization of slurries

Reported by

AIDICO. AITEMIN, CEVALOR and IMM CARRARA


Index

1. Summary of the report .......................................................................................................... 3

2. Introduction of the deliverable ............................................................................................. 4

3. Overview of the industrial sector with high demand of micronized raw materials ............. 7

4. Possible applications of the slurries and preliminary results of introduction of the slurries

as raw materials .......................................................................................................................... 13

Slurries used as raw materials for the cement and concrete industries ................................ 13

Slurries used as raw materials for the agglomerate stone industry ....................................... 17

Slurries used as raw materials for other uses ......................................................................... 28

5. Potencial application of Marble Slurry ................................................................................ 29

Fillers for conversion of waste paper ...................................................................................... 29

Paper Industry - Sludge compatibility ..................................................................................... 30

Fillers and pigments for the manufacture of water paints ..................................................... 30

Plastic fillers (for PP and PVC) ................................................................................................. 31

Neutralization of acidic farmlands .......................................................................................... 32

Production of fertilisers ........................................................................................................... 33

Desulphurisation of fumes from thermoelectric plants .......................................................... 33

Production of animal food ...................................................................................................... 35

Recovery of lead from flat batteries ....................................................................................... 35

Production of Solvay soda ....................................................................................................... 36

Iron and steel manufacture ..................................................................................................... 36

6. Case Studies ........................................................................................................................ 37

Pigments and fillers used in the paper industry ..................................................................... 37

Neutralisation of acidic by-products ....................................................................................... 37

Desulphurisation of waste gas ................................................................................................ 38

Recovery of lead from car batteries ........................................................................................ 38

A new technology of marble slurry waste utilization in roads ................................................ 38

Recycling of Natural Stone Wastes Enriched in Calcium and Lithium for the Manufacture of

New Glass Ceramics and Glazes .............................................................................................. 38

Utilization of Marble Powder Residue in Paper Industry ........................................................ 39

7. Discussion and Conclusions ................................................................................................. 39

8. References and bibliography related to the recycling of slurries ....................................... 41


1. Summary of the report

This report presents the activities carried

out by the partners involved in the

activities of WP2: APPLICATION and REUSE

of the Slurry. The information and data

reported in this deliverable have been

obtained during the execution of the

Subaction 2.1: Identification of potential

uses for slurries. This sub-action has been

coordinated by AIDICO, which has received

the collaboration of AITEMIN, CEVALOR

and IMM CARRARA.

The activities have been carried out during

the period from 01/10/2011 to

30/03/2012. These activities are focused

on the achievement of the requirements of

the sub-action in order to describe and

identify the potential uses of the slurries

and compile this information in a guideline.

The reports present an overview of the

possible industrial applications of the

slurries used for substituting micronized

raw materials in several industrial sectors,

considering not only the requirements of

the raw materials but also the potential

demand of those sectors. In this way, an

introduction of those sectors and the

presentation of pilot laboratory

experiences done by the involved partners

at laboratory scale will be presented for

illustrating the possibilities and the viability

of the recycling procedure for this residue.

Finally, the presentation of the conclusions

and discussion will permit to establish a

starting point to carry out the activities of

the project.


2. Introduction of the

deliverable

Nowadays, the exploitation of natural

stone quarries is performed considering

environmental plans for recovering the

quarries after the end of the extraction

activities, including restoration of holes

and landscapes, reforestation of the area,

avoiding uncontrolled pouring of

pollutants, and re-using of the vegetal soils.

Nevertheless, processing of Natural stone

at factories is still producing a series of sub-

products or residues which originate an

important environmental impact because

those products are usually poured in

dumps.

Figure 1. Mountains of White slurries deposited in abandoned clays quarries in the area of Novelda, Spain.

The nature of the residues produced during

the processing varies depending on the size

of the particles. Part of those residues,

mainly large size particles, are actually

demanded by other industries to produced

agglomerated stone or aggregates used in

the building sector. On the other hand,

micronized particles, such as slurries, are

not frequently reused and are generally

poured in poorly controlled dumps. Slurries

are produced on the elaboration of natural

stone products during different stages of

the processing: cutting of blocks, cutting of

slabs and polishing of the slabs and tiles. In

those processes, very fine particles of the

stone are originated and mixed with water

which transports those residues. Particles

and water form a fluid mixture which is

usually conduced to large decantation

pools, where sediments are deposited at

the bottom. In those pools, water is almost

recuperated and recycled whereas slurries

are treated in filter-press. After filter-press,


the slurry is composed by fine particles and

water with a relationship on weight 80%

particles / 20 % water.

Chemical composition of the marble

slurries allow classifying them as inert

waste according to the European Directive

2003/33/CE due to they are composed

basically by mineral particles (calcite,

dolomite, with trace components quartz,

micas, feldspar, and clay minerals) with

ppm quantities of flocculants and remains

of resins. In case of granite, the slurries

content also significant amounts of metallic

steel grid which are used to facilitate the

cutting process in the gang-saws. These

slurries have similar physic-chemical

characteristics to the fillers that other

industrial sectors are demanding for the

elaboration of their products.

Subsequently, those residues may be used

as raw materials for other industrial

applications after characterization and

valorisation procedures.

The quantification of the slurries problem

in the natural stone sectors has been

tackled to estimate the global importance

in terms of environmental impact. In

Europe the production of natural stone is

around 22.5 Mt (data from 2005, FDP,

2008 annual report) having and estimation

of 6 Mt of slurries (referred to dry slurries).

The total amount of natural stone

processed yearly is varying depending on

the demand of the construction sector;

however, it could be accepted that for each

ton of processed natural stone products;

200 kg of slurries are generated and could

be susceptible of being used in other

applications.

In this deliverable, an detailed analysis of

possible solutions for recycling and

revalorizing the slurries has been done by

means of analysing the industrial sectors

which demand similar raw materials and

studying the previous research studies

where slurries has been used to substitute

conventional raw materials. It is important

to remark that the current management of

this waste is clearly in contradiction with

the established principles of the

environmental legislation, which point out

that recycling and revalorisation of

industrial residues becoming into a raw

material for other industries must be

always desirable to a direct deposition on

dumps.

This deliverable presents, firstly, an

overview of the industrial sectors which

demand actually raw materials with

characteristics similar to the characteristics

of the slurries. We have consider that

according to the requirements of the raw

materials the most promising sectors could

be listed as cement and concrete

production, structural ceramics including

prefabricate concrete products, bricks and

tiles, agglomerated stone industry, and

finally other potential uses such as fillers

for paintings and paper industry. A series

of conclusions will be presented in order to

consider the future applications during the

real scale tests at factories.


Figure 2. Scheme of the production of slurries in the Natural Stone processing plants

SLURRIES

RESIDUAL

WATERS

PRIMARY WATER

POND FLOCULLANT

DECANTATION CONE FLOCULLANT

RECYCLED WATER WET SLURRIES

PRESS FILTER

CUTTING AND POLISHING

PROCESS

RECYCLED WATER

REC

YCLE

D W

ATE

R

PRESSURE PUMP

PUMPING

PUMPING

GRAVITY FLOW MOVEMENTS


3. Overview of the industrial

sector with high demand

of micronized raw

materials

According to up-to-date statistical

information we can see that the waste

production in the processing of natural

stone, at a world-wide scale, reached in

2009 (Montani, 2010) values of about 42.9

million tones, which corresponds to a net

production of the processing plants of

roughly 59%.

Raw

Production

(000 tons)

Waste

Production

(000 tons)

Net

Production

(000 tons)

2003 75000 30750 44250

2004 81250 33300 47950

2005 85250 34950 50300

2006 92750 38000 54750

2007 103500 42500 61000

2008 105000 43000 62000

2009 104500 42850 61650

Table 1. World stone industry. Waste produced in processing (Montani, Stone 2010).

Figure 3. World stone industry. Waste produced in processing (Montani, Stone 2010).

Analysing the precedent data it’s possible

to observe that from 2007 to the present

days the values of

production have a small variation, what

indicates a stabilization of the markets.

Nevertheless it´s important to consider

also that the same relation waste/final

product is occurring through the years

what reflects the lack of improvement in

the overall efficiency of the productive

process. Thus the impact of the waste

production in the environment continues

has an important aspect to be considered


when we talk about the processing of the

dimensional stone.

The search for proper waste management

plans should be a priority together with all

the actions that can provide a reduction of

the wastes production at the source.

According to some data for Portugal,

obtained in the last major survey carried

out in 1998 (National Plan for Industrial

Waste Prevention – PNAPRI – 2000-2015)

were produced annually around 350,000

ton/year of sludge in the manufacturing

sector of ornamental rocks.

The extractive sector is also considered in

the statistics and also presents a significant

value for mud waste generation

corresponding to about 260,000 ton/year.

Thus it can be said that together the two

subsectors related to the exploitation of

the rock for ornamental purposes

produced annually, in Portugal,

approximately 610,000 ton/year.

It’s a fact that during the production of the

marketable elements considerable

amounts of wastes are generated, and we

can consider that the quantity of waste for

both calcite and silicate materials exceeds

always 30% of the raw material and can

reach medium values about 41% (Montani,

2010).

The processing waste can be classified in

three main categories (Figure 1) depending

on the size of the piece (OSNET vol. 9,

2004):

• Large to medium size waste called

scrap, with dimensions of several

centimeters, which originate from

broken or defective slabs. One or

more surfaces may be polished,

depending on the stage of

processing at which the waste was

created.

• Medium to small size waste

consisting of splints, flakes, chips.

These are created during trimming

of blocks or slabs.

• Small size waste consisting of fine

particles such as dust or slurry.

Figure 4. Typical waste types produced during processing operations. (I-Stone, 2006).

1. Processing

1.1. Large-medium

size waste (broken

slabs)

1.2. Medium-small size

waste (broken strips,

chips from trimming)

1.3. Fine waste

(sludge)


In what respects to the waste

production for operation we can

observe the following table which

is considered has reference for

Portugal.

Operation Wastes Quantity

(ton/year)

Sawing Stone debris

Slurry

Dust

Scrap

281.462

Cut and Polish Stone debris

Slurry

Dust

Other wastes

186.044

Selection and

Finishing

Stone debris

Dust

10.542

Table 2. Wastes produced in Portugal in the processing of dimensional stone, for operation (PNAPRI,

2001).

The values corresponding to table 2 are

referred to the total quantities of the

produced wastes. From that we can see

that the slurry production is the highest

with approximately 73% of the total. The

remain part corresponds to stone debris

and other wastes.

The composition of the slurries generated

from the processing activities depends on

the raw material and on the abrading

agents that are used in the processing

equipment which are required to process

harder stones like granite. All processing

operations (sawing, polishing, etc) require

water for equipment cooling and surface

cleaning, and thus slurries are usually

produced with a water content that

depends on the treatment developed in

the factory. Usually it’s assumed a medium

water content around the 20%-30%. The

waste will be either calcium carbonate

based or silica/aluminates based

depending on whether the original

material was marble or granite.

A waste can be considered any material

that has lost its usefulness for a particular

primary use inherent to the activity where

it was generated. In this sense and

considering the fact that the slurries are

constituted mainly with the original

material (Natural stone), while not having

the characteristics to be used in the

ornamental stone market, they keep in

theory the necessary characteristics for

their use as a raw material in other

industrial sectors. This is true especially if

we consider that the chemical constitution

of the sludge, in the case of calcareous

rocks is essentially calcium carbonate, and

in the case of the siliceous stones, silicates,

which are both of them raw material for

several industries.


The management of these wastes in order

to prevent or minimize their adverse effect

in the environment or a better efficiency of

the productive process is an essential key

for the correct functioning of the natural

stone industry considering it’s

sustainability in a more holistic approach

than considering only or in a separated way

the environmental or the economic

aspects.

An adjusted management plan in order to

try to solve the problem of the wastes

proceeding from the stone processing

industry must have in consideration some

alternative solutions to the most common

deposition in superficial dumps,

considering even that it’s possible and

desirable the value addition to the waste

with the correct preparation.

Following what it´s being stated, we can

consider that the processing (sawing, cut

and finishing) of marble and granite stone

generates large quantities of sludge which

have the potential for a broad range of

applications in a number of sectors,

including:

• Cement manufacture

• Concrete products

• Ceramics

• Paper Industry

• Fillers for pigments

• Plastics fillers (for PP and PVC)

• Treatment of acid sulphate soils

• Fertilisers

• Desulphurisation of fumes

• Animal food production

• Bituminous mixes

• Marble resin products

• Recovery of lead from batteries

• Production of Solway soda

• Iron and Steel industry applications

• Glass industry

• Disposal site liners

According to the specification of each

potential industrial application some

special attention in the preparation of the

slurries must be given taking into

consideration a wide range of variables

including: particle size and grading,

moisture content, colour, quality control,

presence of impurities and trace metals,

resource quantities and location, costs of

processing, freight, alternative materials

and so on.

One particular aspect and maybe one of

the most conditioning characteristic of the

raw materials for the referred industrial

sectors is the particle size, since some of

the applications are very exigent and have

very strict ranges. So the preparation and

control of the slurries grading curve is a

fundamental condition for the feasibility of

their use in most part of the applications.

The micronized raw materials are an

important use to consider for the majority

of the listed applications, excluding those

where particle size has a broader range like

the cement manufacture, the concrete

products or the ceramics which are at the

same time less exigent and have the

capacity to absorb the greatest waste

quantities. The problem with this “high

consuming” applications is that the waste

doesn´t have any added value and it’s

management is depending in a decisive

way from the costs related to the travel


distance between the producer and the

end user.

From the analysis of some data regarding

the use of mineral raw materials, namely

those related to Calcium Carbonate, it´s

possible to observe that, in Portugal, the

extraction of the so called industrial

minerals involving carbonated rocks has

been decreasing for the last three years.

However we must consider that the

reported uses are related mainly to the

sector of construction, what justifies the

less consumption of cement or quicklime,

and for the same reason the raw materials

associated with their production.

The quarries in Portugal produced in 2010

industrial minerals achieving values around

the 14 thousand tons, where the minerals

for the production of cement and

quicklime are the majority with

approximately 11 thousand tons.

The following table and graphic represents

the evolution in Portugal for the period

2000-2010, of the extracted minerals from

carbonated rock quarries.

Figure 5. Extracted minerals from carbonated rock quarries in Portugal.

As we stated above the use of calcium

carbonate is much more diverse and it´s

not restricted to the construction sector,

have high demands in other industries.

Recent news states that the market of

CaCo3 is a growing market being expected

for example has reported by Global

Industry Analysis, Inc, that the global

calcium carbonated market will reach the

108.5 million tons by 2015:

“GIA announces the release of a

comprehensive global report on Calcium

Carbonate markets. The global market for

calcium carbonate is forecast to reach

108.5 million tons by the year 2015.

Increasing use of calcium carbonate in

paper industries; growing demand for


precipitated calcium carbonate (PCC)1 and

nano calcium carbonate, conversion of

existing paper mills from acid-based

process technology to alkaline-based

process technology are few of the key

factors influencing market growth. Asia is

expected to spearhead growth in the

consumption of PCC worldwide, fuelled by

the significant rise in number of paper mills

and growth in plastics sector in the region

over the recent years. Meanwhile, ground

calcium carbonate (GCC)2 continues to

enjoy increasing demand from the paper

industry in paper coating applications as

well as fillers.”

(http://www.prweb.com/releases/calcium_car

bonate/ground_precipitated/prweb8064439.ht

m)

According to what is reported the Calcium

Carbonate is assumed has the “principal

inorganic mineral, primarily used as

commercial and functional filler in paper,

rubber, plastic, architectural materials,

coatings and light chemicals. Along with

talc and kaolin, the mineral (known as filler

or body pigment) finds extensive usage in

metalloid mineral applications. In addition,

calcium carbonate has long been

recognized as a useful additive for

thermoplastics and in PVC for many

applications.”

Asia-Pacific is actually the largest market

for the CaCO3, followed by Europe. By

application the Paper industry, is the

largest market for the ground calcium

carbonate, following by the plastic

industry. The ground calcium carbonate

1 PCC is made by direct carbonation of hydrated lime, known as the milk of lime process. (www.specialityminerals.com) 2 GCC is obtained directly from the limestone and marble by physical processes (crushing).

(GCC) is the preferred because of its high-

quality performance in the productive

process and also for the brightness it

confers.

In the plastic industry the GCC is the most

common filler although it competes with

Alumina Trihydrate and Talc in more

demanding applications.

The global consumption of precipitated

calcium carbonate for the paper industry is

stated to be largely concentrated in Asia

being Europe in the second position and

North America in the third. Nevertheless

the expectations for the future of the

market are quite different since Asia is

expected to grow and the others

particularly the European market is

expected to decrease due to the economic

recession.


4. Possible applications of the

slurries and preliminary

results of introduction of

the slurries as raw

materials

In this chapter of the deliverable, it is

pretended to evaluate the possibilities for

recycling the slurries after the valorisation

and characterization process according to

the demand of raw materials by other

industries. In the previous chapter, a

complete overview of the industries

demanding raw materials have been done,

and subsequently, it is intended here to

show the experiences which have been

previously developed in order to obtain

products which have been performed using

slurries as raw materials. Next points

resume those experiences and decipher

the future actions to carry out during the

real scale tests.

Slurries used as raw materials for the

cement and concrete industries

The cement and concrete industries could

be potential sectors where the marble

slurries could be used as raw materials.

Those sectors demands important

quantities of carbonates to elaborate the

products either as a raw material for the

elaboration of the cement or as a filler to

correct the granulometry and fine content

in the concrete industries. Several studies

have been carried out at laboratory scale in

order to introduce the slurries in the

production of those products showing

positive results, which will be outlined

here:

Use of marble slurries for the production of

cement

Cement is probably the most demanded

product for the building and construction

sector. The estimations about the global

production of cement in the world are

around 3300 millions of tons during 2011,

which means that a huge amount of raw

materials are demanded in order to

produce those amounts of cement. Raw

materials for cement could be resumed as

clays (silicates) and limestone. Those raw

materials are mixed and calcined for the

preparation of the clinker and after a very

fine milling process the cement is obtained.

As it was previously indicated, mineralogy

of the marble slurries (specially derived

from the processing of calcitic marbles and

recrystallized limestone) is basically

carbonates. Those slurries could

satisfactorily substitute part of the

limestone used in the fabrication of

cement. Nevertheless, even when the

suitability of the slurries as raw material for

the fabrication of cement is demonstrated,

the economic feasibility of the recycling

process will deeply depend on the distance

between the plant of processing natural

stone and the plant for fabrication of

cement.

Moreover, the control of the slurries

should be done in concordance with the

specifications of the raw materials

demanded for the fabrication of concrete,

and in this way the chemical composition

of the slurries must be controlled to ensure

the quality of the concrete.


Considering those premises, it can be

established that the recycling of the

slurries from marble industries could be

very efficient when the processing plants

of natural stone are relatively close to

plants for fabrication of cement. In those

case, the recycling of the slurries could be

total due to the demand of limestone of

the cement plants will probably pass the

production of slurries in the companies.

The costs associated to the valorisation and

characterization of the slurries is smaller

than the cost of conventional raw

materials, so it could be considered as

economically feasible.


Self-Compacted concrete

Self compacted concretes were firstly

developed at Japan in order to enhance the

durability of the structures and increase

the sustainability of buildings at the decade

of the 80. Since that moment, SCC has

been extendedly used worldwide for civil

applications and building, representing the

most developed technology of the

concrete in last decades. This product can

be defined as the concrete compacted by

its own weight without the need of

vibrating mechanical energy or any other

system or method with no segregation,

bleeding or thick aggregate blocking.

In order to obtain the characteristics

properties of fluidity and cohesion at fresh

stage of the SCC, it is usual to increase the

volume of the mixture paste. The

increment of volume is also related to the

lubrication of the systems triggering the

fluidity capability of the mixture. Increased

paste volume will demand greater cement

content and/or the use of fine minerals

known as fillers due to their filling function,

with a particle size smaller than 125 µm;

for example, micronized limestone is

currently one of the most common fillers,

obtained by the crushing or pulverizing

process for aggregates. It is in this context

where slurries could be used after a

process of valorisation as potential filler in

SCC.

Essentially, marble slurries are mainly

composed by calcium carbonate, which is

chemically comparable to the crushed

limestone filler produced in the crushing

plants. Many researchers have

demonstrated in different studies that the

addition of calcareous (limestone)

micronized is suitable for the elaboration

of the SCC increasing the cohesion of the

admixtures and substituting part of the

cement and sand without affecting the

resistance of the concrete.

Moreover, some of those studies

compared the differences between adding

slurries or crushed fillers demonstrating

that the effect of adding the slurries could

be even advantageous against the crushed

fillers due to a high resistance to

compression and a notorious low

permeability. Other tests performed in

laboratory have shown that an increment

in the filler content could be also reduce

the addition of additives, decreasing, in this

way the cost of the SCC and keeping into

mind that the resistance of the concrete

are always comparable to the resistance

with conventional fillers and methods.


The above reasons point out that the

recycled slurries could be considered as an

excellent raw material for the elaboration

of SCC, permitting not only to re-use this

current waste but also to develop new SCC

with better performance and more

economic.

Nevertheless, there is still a significant lack

of studies at real scale tests and only a few

authors (Correia Gomes et al., Girbes I. Et

al, Calmon et al.) have carried out more

detailed studies about this topic. In some

of those studies, the results are even more

positive demonstrating that additions of 50

% in weight respect to the cement do not

affect the, or even enhance, the final

properties of the SCC products. Other

authors (Calmon et al.) demonstrated that

the slurries could entirely substitute the

addition of limestone fillers maintaining, or

even enhancing (Topcu et al) the

properties of self-compacting and

resistance of the SCC.

After all those studies, a complete

comparison between the characteristics of

the limestone fillers and the slurries was

done by Valdez et al. showing that the

grain size distribution of the slurries is

slightly smaller than the filler (figure 2) and

the chemical composition of both materials

is similar (the silicates content in the fillers

is higher than in the slurries but this issue

that not play a direct role in the

development of SCC).

According with the studies, it has been

possible to determinate that the SCC using

valorized slurries have shown very

promising results. The addition of the

slurries has not negatively influenced any

of the most important properties

demanded to the SCC and, therefore, those

residues could be considered as potential

raw materials for this industrial sector.


Figure 6. Grain size distribution and comparison between limestone filler and slurries (after Valdez et

al.)

Table 3. Chemical composition comparison (according to Valdez et al.)

In conclusion, the studies at laboratory

scale that until now have been carried out

in order to obtain a fruitful recycling of the

slurries in the industry of the SCC have

demonstrate a real potential as raw

material not only in the concrete paste but

also in the final SCC. Slurries may be

considered as appropriate filler after a

valorization process focused on the drying

and disaggregation of the slurries. This

issue represents several advantages for the

industry:

1.- It is a continuous production of this raw

material which could be supplied to the

demanded industries.

2.- The performed tests have demonstrate

that the properties of the SCC are similar or

even better than conventional products

with calcareous filler;

3.- Part of the cement may be substitute

with the slurries, reducing, subsequently

the cost of the final products.

Last, but not least, the recycling of this

residue produces and enhancement of the

environment by different ways such as

avoiding of uncontrolled pouring, reducing


the needs of exploit micronized limestones,

supply of fillers with low energy demands,

etc.


precast concrete

The industry of precast concrete is

nowadays producing a vast amount of

products which are used in construction

and building to facilitate the building

process, decrease the prices and costs and

assure the sustainability of the sector.

Moreover, those products have many

advantages respect to the casting on the

building places such as control of the

parameters of curing, safety of workers,

repeatability using the same moulds, etc.

doing those products suitable for many

different applications in the building

sector.

Self-compacted concrete or standard

concrete could be used for the fabrication

of precast concrete, but currently it is most

common to develop products based on

SCC. In this way, as it was explained above,

the marble slurries could be used as a

potential raw material for this industrial

sector because the properties and

characteristics of the slurries (after a

previous valorisation process) are similar

and equivalent to the properties of the

micronized limestone that this sector

demand for the fabrication of precast

products. Furthermore, in this case, the

industry also requests aggregates and sand

which could be also supplied by the natural

stone companies due to those companies

produce and important volume of residues

of rocks which could be milled and used as

aggregates.


agglomerate stone industry

Agglomerate stones (artificial stone) are

nowadays considered as a high-added

value product for the building sector. In the

construction sector, many companies are

producing different types of composites

imitating the visual aspect of the natural

stone. Those products have a good

acceptance by the final users, specially for

countertops, tables, and paving products.

Many different typologies of agglomerate

stones are in the market and all of them

demand micronized minerals for the

fabrication process. Agglomerate stone

consist basically in a mixture formed by

mineral fillers (with different

granulometries) and resins. The ratio

between fillers and resins is approximately

90-94% filler/10-6% resin.

Generally, the elaboration process of these

materials is performed by means of a

mixture of the thermal-stable resins with

the mineral fillers, which is strongly

agitated; afterwards, the mixture is poured

in moulds where vibro-compression can be

applied. In this moulds, the polimerization,

hardening and curing of the resins occur.

Then the pieces are extracted from the

moulds and finally a polishing treatment is

applied to obtain the polished finishing of

the materials. The pieces are very resistant

to flexural and compressional strengths

and lighter than conventional natural stone

products, on the other hand the thermal

resistance of those materials is limited due

to the presence of the resins.


In this context slurries could be considered

suitable raw materials for the process after

drying (for those resin based on solvents)

or wet (when the resins are water-bone

resins). The recent development of water-

borne thermosetting polymers have been

possible the addition of wet slurries (no

need for drying!) doing this process

economically feasible. The higher price of

the water-borne resins is compensated by

the savings produced by the reutilization of

slurries as raw material

AIDICO has been working on this topic in a

previous research project in order to test

the possibilities of recycling of the slurries

for agglomerate stone. In those studies,

the elaboration of agglomerated stone was

done using water-borne thermosetting

resins and slurries with the grade of

humidity normal after the filter-press

process (around 20%).

First stages of the studies were focused on

the identification of the properties and

characteristics of the slurries by means of

determination of the grain size distribution,

mineralogy, the chemical composition, and

the colour because those factors may

influence the final aspect and properties of

the developed products. Some of the

results are shown here in order to provide

a general overview of the raw material:

• Grain size analysis by laser ray diffraction.

Due to the very grain size of the slurries

particles, a dispersion of the particles using

ultrasounds was previously done, and after

adding distilled water the measurement

was performed and recorded in the

following table.

Obtained data Particle size, µm

d(0.1)

10 % of particles with diameter smaller than 1.259 μm

d(0.5)


d(0.9)


D[4.3] average diameter of the particles 12.239 μm

Table 4. Grain-size analysis


Particle Size Distribution

0.01 0.1 1 10 100 1000 3000

Particle Size (µm)

0

1

2

3

4

5 V

olum

e (%

)

RESILODOS/ RBO3O2O5, 10 February 2005 13:54:33

Figure 7. Results of the grain-size analysis of the slurries particles

• Mineralogy and chemical composition

Determination of the mineral and chemical composition of the slurries coming from the

processing of marble were done using two different techniques: X ray fluorescence and X-ray

diffraction. The results of the analysis are shown below:

SiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O TiO2 P2O5 SO3 L.O.I

0.36 0.00 0.04 0.01 0.44 55.32 0.02 0.01 0.02 0.25 0.10 43.35

Table 5. Chemical composition of the slurries with main chemical groups

Figure 8. X-ray diffraction diagram

The X-ray diffraction diagram shows that the slurries is mainly composed by calcium

carbonate (calcite) with traces of dolomite and clay minerals

0

929

1858

2787

3716

4645

5574

6503

7432

8361

9290

5 10 15 20 25 30 35 40 45 50 55 60 65 70

2Theta (Degrees)

INT

EN

SIT

Y (

Arb

itra

ry U

nit

s)


• Colour analysis

The measurement of the colour of the slurries was done using a spectrum colorimeter. This

parameter is strongly influenced by the quantity of chromatic elements present in the slurries

(Fe, Cr, Al…) and varies according with the processed natural stone. Nevertheless it is possible

to establish systems for separating the different colour of the slurries which could be used for

different application as “pigment filler”. The measurements are:

Sa

mp

le

L* (1

)

De

sve

st

a*

(2)

De

sve

st

b*

(3)

De

sve

st

i-b

lan

cura

De

sve

st

i-a

ma

rill

ez

De

sve

st

i-co

lor

De

sve

st

1 93,78 0,10 0,46 0,17 4,79 0,21 66,98 1,00 8,10 0,40 -2,92 0,30

2 92,34 0,13 0,81 0,18 6,13 0,31 57,12 1,25 11,70 0,47 -4,11 0,24

3 92,74 0,14 0,97 0,16 5,88 0,27 59,32 1,34 10,68 0,48 -4,26 0,26

4 91,53 0,14 1,73 0,25 6,96 0,23 51,29 0,89 13,46 0,38 -6,06 0,41

Table 6. Colour analysis

Afterwards, several mixtures with different proportion between slurries and resins were tested

and finally the developed products were characterized showing in general a good behaviour.

Nevertheless, the results are shown that the addition of dry slurries could produce better

results, especially when other course filler are also added to the admixture.

Figura 9. Samples of products performed with wet slurries.


Samples of products performed with wet

slurries.

The addition of wet slurries implies a

longer hardening time due to the

important water contents that are

introduced into the system. Moreover, the

addition of micronized slurries produces

and effect of filling the voids. This effect is

even more evident when sand particles are

also added to the mixture producing a

decrease on the hardening time and an

enhancement of the mechanical properties

of the products. In general, the tests have

also shown that the use of dry slurries with

conventional solvent-borne resins produce

products with better mechanical

properties, especially in terms of durability

and ageing of the samples.


structural ceramic industries (tiles and

bricks)

Ceramic industry could be a potential user

of marble slurries, as raw materials.

Moreover has been analyzed which is the

actual situation of the market with regard

to prices, utilized amounts, delivering

times, transport and quality of the calcium

carbonate utilized in the ceramic industries

studied.

The European Union (EU) ceramic industry

is an integral part of the Community’s

economics structure, and is perhaps one of

the area’s oldest industries. It covers a

wide range of sub-sectors ranging from the

more traditional (tableware, wall and floor

tiles) to the more high-tech (technical and

refractory ceramics).

The EU ceramic industry is a world leader

in producing value added, uniquely

designed high quality ceramic products

manufactured by flexible and innovative

companies, mainly SMEs. The ceramics

industry represents an annual turnover of

around € 30 billion, accounting for

approximately 25% of the global

production, and around 350,000 jobs

throughout the EU.

The major producing countries in the EU

are Italy, Spain, Germany, the UK and

France. Production in the new Member

States of the EU appears to be strongest in

the Czech Republic, Poland and Hungary,

which all have strong ceramics sectors and

have traditionally exported to other EU

countries.

The EU ceramic industry is export oriented

with 30% of its productions sold outside

the EU market. It is generally competitive

both domestically and on international

markets. However, since the last decade

the market situation has changed

considerably with the rise of low-cost

products from new competitors in

emerging and developing countries (China,

Brazil, India, United Arab Emirates) while

persisting trade barriers prevent effective

access to important new markets.


Figure 10: European ceramic industry production value (2005-2010). Cerame-Unie.

Spain’s ceramic tile or fine industry is one of the country’s most dynamic and innovative

sectors, and is positioned firmly at the forefront of the worldwide ceramic tile industry in

terms of technological development, design and standards of service.

65% of its global turnover comes from exports, and the rest from sales on the domestic

market. The ceramic tile sector is a key industry for the Spanish economy, providing a clear

trade surplus for the country as a whole, with a coverage rate in excess of 2,000% (2010 data).

The sector's vast export capacity has positioned it amongst Spain's top 12 exporters and as the

second largest surplus contributor to Spain’s trade balance.

One of the most notable features of the Spanish ceramic tile sector is the industrial hub in the

province of Castellón (industrial cluster), centred in the area bordered to the north by Alcora

and Borriol, to the west by Onda, the south by Nules and the east by Castellón de la Plana. In

2010, around 94% of Spain’s total production came from this province, home to 81% of the

companies operating in the sector. The Spanish ceramic tile sector is estimated to provide

direct employment for around 16,200 workers, mainly in small and medium-sized enterprises.

Employment · 16.200 direct employees and more than 5.000 indirect. Total Sales · 2.548 million €

Industry Production and Sales

2005 2006 2007 2008 2009 2010

Production 609,20 608,40 584,70 495,20 324,40 366,00

Domestic Sales 1.609,20 1.799,10 1.871,00 1.460,30 918,00 801,00

Export 2.040,90 2.183,10 2.295,00 2.210,90 1.673,20 1.746,80

Total Sales 3.650,10 3.982,20 4.166,00 3.671,20 2.591,20 2.547,80

Table 7. Sales in EUR millions and production in square meters millions. Spanish ceramic tile industry.

(ASCER).

The Spanish structural ceramic sector is the

largest producer in Europe of ceramic

materials for building, with a production of

over 10 million tonnes per year (2009). This


sector is composed by 280 companies (year

2009). The Spanish structural ceramic

sector is estimated to provide direct

employment for around 9300 workers. The

Spanish structural ceramic sector is the

industrial hub in the regions of Castilla - La

Mancha, Andalucia, Valencia and Cataluña.

Besides, the calcium carbonate is used

both for structural ceramic products

(bricks and tiles) and for fine ceramics

products (pavements and coverings:

pastes and enamels), mainly white. The

calcium carbonate is added to the clay

mixture to confer it special properties

such as whiteness or correct certain

pathologies such as the expansion

caused by humidity; this last showed to

be an application with high potential

even using the marble waste mud itself

as a whole.

Then, the main re-using application

detected is the inclusion of the marble

waste mud in the clay paste to produce

salmon-like colour façade bricks. The

standard clay paste for salmon-like

colour façade bricks is normally

obtained by mixing clay for red ceramic

and clay for white ceramic (calcareous

clay); mixtures (of samples and clay for

red ceramic). The manufacture of

salmon-like colour facade bricks used

up to 15 % of CO3Ca and in order to

correct certain pathologies such as the

expansion caused by humidity could be

necessary between 2 % - 3 % of calcium

carbonate.

The two following tables show the

requirements and characteristics for the

CaCO3 and clays used in ceramic industry.

Figure 11. Spanish structural ceramic industry production (2009). HISPALYT

Characteristics Ud. Value


Characteristics Ud. Value

CaCO3 (CaO) % 99,3 (55,61)

SiO2 % 0,30

Al2O3 % 0,10

MgO % 0,20

SO3 (S) % 0,1 (0,04)

Loss on ignition (LOI) % 43,6

Whiteness (dry) % 89

Humidity % 0,14

Granulometry (µm) %

100>x>50 2,1

50>x>20 14

20>x>10 11,7

10>x>5 17,8

5>x>2 40,1

x<2 14,3

Table 8. CaCO3 characteristics in structural ceramic industry (preparation: own source).

Requirements Ud. Value

CaCO3 % Very high

F2O3 % 0,05

Granulometry % 98 % < 27 µm

Humidity % 0,1 (0,04)

Supply Regular and

homogeneous

Table 9. CaCO3 requirements in fine ceramic industry (preparation: own source).

Id Quartz Feldspar Calcite Dolomite Phyllosilicates

Red Clay 7 % 21 % - - 72 %

White Clay 3 % - 63 % Signs 34 %

Table 10. Mineralogical composition of clays (preparation: own source).

With the obtained data from the market

survey and with the specifications of use

that we have

been taken as reference in each case,

below are indicated the possibilities of


application of the wastes for ceramic

industry.

• The ceramic sector saw the

utilization of the marble mud

wastes as possible, as example, for

the manufacturing of salmon-like

coloured façade bricks, if that did

not alter negatively the physical-

mechanical characteristics of the

ceramic products.

• The marble mud waste can be a

good substitute of the commercial

calcium carbonate for its use as

corrector of the expansion due to

humidity in ceramic products.

• The muds obtained from the

mixture of different marble (kind

all-one), have lower possibilities of

reusing in some applications

(caused by color and particle size

differences)

• The humidity content of the marble

mud wastes is a problem that has

influence in the feasibility of their

use of them in other industrial

applications, particularly in the

ceramic industry. Up to this

humidity value, the mud wastes

can be transported by means of

tub-type trucks without problems.

This problem can be solve carrying

out some simple control

procedures during their pre-

treatment. It must specially be

controlled the humidity of the mud

wastes at the exit of the press-filter

that, could never be higher than

27%.

• The drying of the mud wastes could

be carried out without the need of

making high investments in drying

installations, so far as it can be

performed by natural means at

ambient temperature, being

necessary, in this case, around

three weeks of natural drying for

the mud wastes to have an

acceptable humidity value (<10%)

for their posterior manipulation.

• With regard to the application

of the recycled (from marble

wastes) calcium carbonate to

the ceramic industry (for

increasing whiteness and/or

conferring certain properties)

detailed studies had been

carried out (AITEMIN) for

determining the goodness of

the recycled waste as additive.

Characterization muds testing

The characterization testing carried out

and the methods utilized are shown in

table below. Marble waste samples were

provided by marble transformation plants

from Spain, Portugal and Italy.

Characterisation results are shown in Table

12.


Table VI: List of characterization testing.

Testing Procedures or techniques used

Mineralogy X-Ray Diffraction

Chemical

Analysis

Elements expressed as oxides were determined by X-Ray

fluorescence

Sulphur was determined with elemental analyzer LECO

PLAS ICP-AES Spectroscopy determined the rest of elements

Granulometry Galai-CIS-1

Whiteness HUNTER; ASTM E3 13

Humidity PE-027 (internal procedure)

Table 11: List of characterization testing.

SAMPLE 1 2 3 4 5 6 7MINERALOGY % Calcite 78 86 100 100 0 100 100

% Dolomite 22 14 0 0 100 0 0% Quartz 0 0 0 0 0 0 0

CHEMICAL % CaO 50,11 52,77 55,89 54,3 31,79 54,4 52,63ANALYSIS % MgO 4,43 2,74 0,59 1,24 21,37 0,55 1,43

% SiO2 0,72 0,33 0,53 0,39 0,37 1,1 2,11

% Al2O3 0,33 0,45 0,29 0,4 0,39 0,75 1,01

% Fe2O3 0,11 0,09 0,09 0,13 0,37 0,14 0,15

% TiO2 0,006 < 0,10 < 0,10 < 0,10 < 0,10 < 0,10 < 0,10

% K2O < 0,10 < 0,10 < 0,10 < 0,10 < 0,10 < 0,10 < 0,10

% P2O5 < 0,10 0,04 0,05 0,02 < 0,02 0,11 0,03

% S 0,02 0,02 0,02 0,04 0,02 0,02 0,02% Na2O 0,08 0,027 0,094 0,04 0,027 0,04 0,054

ppm Mn 41 40 22 51 134 54 81ppm Ba 6 7 9 8 5 6 23ppm Nb < 10 < 10 < 10 < 10 < 10 < 10 < 10ppm Zn 14 < 10 < 10 < 10 < 10 < 10 167ppm Cu < 8 < 8 < 8 < 8 37 < 8 253ppm Ni < 10 < 10 < 10 < 10 < 10 < 10 < 10ppm Cr 7 3 5 < 2 < 2 5 4ppm Pb < 10 < 10 < 10 < 10 < 10 < 10 16ppm As < 20 < 20 < 20 < 20 < 20 < 20 < 20ppm W < 10 < 10 < 10 < 10 < 10 < 10 < 10ppm Sr 142 115 86 172 101 86 160% LOI 44,05 43,56 42,46 43,45 45,64 42,89 42,48

GRANULOMETRY % x <2 31,47 15,14 9,54 14,55 8,5 9,11 8,67% 5>x>2 48,03 42,93 41,33 46,26 29,02 30,24 28,78% 10>x>5 20,36 20,54 24,98 31,09 24,04 16,62 24,22% 20>x>10 0,14 17,49 17,5 8,12 20,25 11,7 20,71% 50>x>20 0 3,89 6,64 0 18,19 15,81 17,61% 100>x>50 0 0 0 0 0 16,5 4,65

WHITENESS WI Hunter 83,4 92 90,3 95,3 87,4 87,6 94,7WI ASTM E313 34 61,3 54,7 81,7 37,1 40,3 73,9L 88,88 95,33 93,84 96,49 93,23 92,57 96,78

Table 12. Characterisation results of marble wastes.

An abstract of the main results is showed:


With regard to mineralogy, Calcite (CaCO3),

Dolomite (CaMg (CO3)2) and traces of

Quartz (SiO2) are the expected main

components.

Samples picked after the press-filter are

mixed wastes with higher proportion of

calcite (78-86%) than dolomite (14-22%)

while the rest of samples are practically

pure calcite except one of them which is

practically pure dolomite.

Regarding the chemical composition the

results suit those of the mineralogical

composition showing a major composition

of CaO and a minor one of MgO (which is

relevant for the samples with dolomite).

There are also present traces of SiO2 and

metallic oxides such as Al2O3 and Fe2O3,

apart from Sulphur and trace metals.

Granulometrical profiles show a very low

fraction over 20µm, which is 0%–3.9% for

samples picked after the press filter and

0%–6.7% for samples picked after the

sawing process, while it is higher (18.2%–

32.3%) for samples picked after the cut &

polishing processes and after decanting.

All the samples analyzed have a Fe2O3

upper to the requirements for fine ceramic

industry (0,05 %).

The results confirm than the utilization of

the marble mud wastes as possible, for the

manufacturing of salmon-like coloured

façade bricks.

Technological testing at laboratory scale

Once that was confirmed the possibility of

use of the marble wastes in the structural

ceramic industry some technological

testing were made at laboratory scale to

verify that the use of marble waste as

substitutive of the calcium carbonate do

not suppose one lost of the physico-

mechanical characteristics of the ceramic

product.

The laboratory testing were made to check

the influence of the mud for combating

expansion due to humidity in the ceramic

products and also to check its behaviour in

the process for manufacturing façade

salmon-like colored bricks.

0,677

0,753

0,583

0,479

0,538

0,439

0,367

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

Without addition With 1% CaCO3 With 5% CaCO3 With 10% CaCO3 With 1% waste # 1 With 5% waste # 1 With 10% waste # 1

VALUE (mm/m)

FIRED TEST PIECE

Figure 12. Correction expansion due to humidity. Fired test pieces.


Conclusions

According with the results:

• That all types of mud can be

utilized as additive to the structural

ceramic paste to correct the

expansion due to humidity.

• The utilization of the marble mud

wastes (also the commercial

CaCO3) to combat this pathology in

ceramic pieces has a negative

incidence (as it could be expected)

on the mechanical resistance of

the products, and could limit their

use for some types of products.

• The relation quality/price of the

calcium carbonate used, the very

homogeneous supply of this and

the low price made non-viable the

utilization of wastes marble in fine

ceramic sector.

• The high humidity content of

slurries and the high cost of

transport made non-viable the use

of marble waste in fine ceramic

sector..

Figure 13. Powder of mud and test samples

obtained with different % of muds

In conclusion, the marble mud waste can

be a good substitute of the commercial

calcium carbonate for its use as corrector

of the expansion due to humidity in

structural ceramic products, but it´s not

possible reuse marble muds into fine

ceramic industry by market (relation

quality/price of the calcium carbonate used

in this moment) and technical reasons

(humidity and Fe2O3 content)

Slurries used as raw materials for

other uses

The last two decades have been quite

productive regarding the development of

studies aimed at the assessment and

analysis of the use of waste from cutting

and sawing of natural stone, slurries in

particular, in other industrial activities.

It is true that scientific and technical results

have been positive and in general quite

indicative of a high potential for the use of

these materials as raw materials in various

sectors with qualitative requirements

ranging high and low exigencies, as the

pharmaceutical industry, inks, paper,

animal feed, building, etc.

However it turns out in practice that some

factors, mainly economic, overlaps the

technical possibilities and are preventing

the regular use (in significant quantities) of

these materials which could be considered

by-products. Following this the values for

the reuse and/or recycling are kept low

and the environmental impacts associated

with the current treatment – soil

deposition - prevails.

Although in general it is not possible to

consider that it was achieved a main

solution for the recovery of the slurries

produced in the manufacture of the

natural rock, it is possible to present some

successful case studies that validate

experiences that have been made and

continue to be developed, in order to


implement, mainly calcium carbonate, in

industries that need this chemical

compound as raw material.

Usually when it tackles the issue of the

management of sludge, or other residues

derived from the production process of

dimensional stones, the main approach

goes toward uses that can absorb the

largest possible quantity of residue and

therefore are not as demanding in terms of

characteristics of the raw material. This

uses include the generality of those related

to the construction, highlighting the

inclusion of waste in the manufacture of

cement, bituminous, concrete products, or

structural ceramics.

These reuses may have a very important

role in the resolution of the current

environmental problem created by the

deposition of waste at landfills; however

they present a problem that objectively, is

coming to derail the practical

implementation of that solution, already

perfectly validated. This problem has to do

with purely economic factors related to the

transport distances between the waste

producer and the location of the “recycling

plant” (cement and concrete products

factories, structural ceramics factories).

Since the residue has a low added value,

even though you do not need any extra

cost with their preparation and that the

end-user receives also at no cost (or

payment), the price of transport under the

responsibility of the producer turns

unfeasible the waste treatment under

these circumstances.

So it is important in addition to solutions

that consider massive uses, but only are

feasible if the deployment of the

"treatment place" is in the immediate

vicinity of the waste production areas,

consider other solutions of reuse that even

needing the accounting of additional costs

for the chemical or physical preparation of

the sludge pass through an appreciation of

this by-product and make it "desirable" to

other industries which, although more

exigent, may pay the added value, wich will

eliminate the distance factor as a limitation

for the use of this raw material.

Italy assumes itself as a country at the

forefront of this kind of experiences,

mainly in their regions related to the

marble industry such as Carrara and

Verona. So much of the case studies for the

reuse of sludge resulting from the

processing of natural stone, have been

taking place in Italy. However the concern

with the management of the stone wastes

is transversal and occurs in most countries

where the manufacturing sector of rocks

presents some meaning.

To define alternative paths for the reuse of

the slurries is important to consider the

specifications of some applications and

also some experiments conducted with

success.

5. Potencial application of

Marble Slurry

Fillers for conversion of waste paper

In the production of paper from waste

paper, the latter is mixed with water in a

pulper that grinds it into a pulp. This pulp is

then slowly purified by removing impurities

(metals, plastics, etc.) depending on how

thick the finished paper should be. Then,

the cleaned and purified pulp is ground

more and put in a mixer with fillers,

pigments and more water. The mixture is


very thin (with water making up to

approximately 60 %) and poured into a net,

on which the paper begins to be produced

(which basically involves removing all

excess water). Part of the water is removed

by gravity as it filters out of the net, while

other parts are removed by suction boxes.

Later on, the net is passed through various

presses, which remove more water, while

the last drying operation involves passing it

through hot cylinders which dry out the

paper with steam. Then, the dry product

passes through a polishing device which

presses it before rolling it up: the paper is

now ready to be converted into different

types of paper: glossy paper in particular is

a special type of paper that takes ink well

and must have an even and compact

surface. Calcium carbonate is added to the

mixture at the very beginning along with

fillers and pigments, and is added again

during the polishing stage, when the paper

must become suitable to take ink.

Depending on the type of paper, the

percentage of calcium carbonate added as

filler ranges between 4 % and 10 %, and

similar amounts are added during the

polishing operation. It must be noted that

kaolin and talc can also be used as fillers,

but calcium carbonate has become

increasingly important recently, since

kaolin (which used to be commonly used as

a pigment) is much more expensive to

extract and transport than calcium

carbonate. Paper products using calcium

carbonate as a pigment are: paper and

cardboard for graphic applications, paper

rolls for newspapers, writing and printing

paper, white cardboard and board (except

kraft paper), white packaging paper and

cardboard. Please note, however, that

calcium carbonate somehow wears out the

paper nets (depending on its

rhombohedral crystallisation) even if not

all carbonates are equally abrasive. To

reduce abrasion, the CaCO3 should have 60

% of its particles under 2 microns, resulting

in 50 % to 90 % of the particles used being

under 2 microns. The product is usually

supplied as a watery suspension or slurry,

stabilised by polyacrylic dispersants. In

addition, the filler should contain low

amounts of silica, aluminium silicate, iron

oxide, iron sulphur, etc. since such particles

damage the net and alter the colour

(white) of the finished products.

Paper Industry - Sludge compatibility

The use of the calcareous marble sludge

involves a preliminary selection of the

colour, particle size and purity of the

sludge. They should therefore be ground

beforehand to produce particle sizes that

are 100 % smaller than 50 microns and at

least 60-90 % smaller than 2 microns. In

addition, they should contain high amounts

of CaCO3 (at least 95 %), low amounts of

silica, and they should be evenly white and

contain no metal dust or impurities that

could alter the colour of the finished paper.

Humidity should not be a problem since

the finished product is sold as slurry. In

conclusion, white marble sludge seems

perfectly suitable for the purpose, once

they have been adequately ground and

sifted.

Fillers and pigments for the

manufacture of water paints

Calcium carbonate is used in the

formulation of paints both as filler and as

pigment. Fillers are mixed with resins and


pigments, and then finely dispersed in a

number of successive emulsions. In

particular, CaCO3 is used as an amorphous

material to make water paints, and as a

crystalline material to make primers (such

as anti-rusting agents). In water paints,

that make up approximately 90 % of

CaCO3-based paints, the calcium carbonate

fillers depends on the type of finished

product, ranging between 10 % and 50 %

for interior applications. Talc or kaolin are

generally preferred for exterior

applications.

The particle size of the limestone is

carefully checked since particles larger

than 60 microns would cause great

problems when mixed: at least 50 % of the

limestone used usually has a particle size of

less than 2 microns. Even if the

composition of the filler is usually 98%

calcium carbonate, 1% humidity and 1 %

impurities, such as silicates and other

minerals, an extender containing more

than 90 % CaCO3 is considered acceptable

provided iron, lead and other ore contents

are low enough not to alter the white

colour of the product, which is essential for

water paints. Limestone is generally used

in the form of dust: solvent paints cannot

contain more than 1-2% humidity, while

water paints contain about 40 % water, so

products having a humidity of 25 % to 30 %

would not be a problem.

Fillers for pigments - Sludge compatibility

The use of calcareous sludge could be

compatible with the production of water

paints, in which the humidity level of the

raw material is not important. Restrictions

on the calcium carbonate content (which

must exceed 90 %), whiteness degree and

metal contents that could alter the colour

can be solved, provided the sludge is

adequately selected. However, problems

remain with the particle size, so the sludge

should be ground and selected

beforehand. Consumption could be really

high, since water paints are largely used in

the building industry.

Plastic fillers (for PP and PVC)

Polypropylene (PP)

Polypropylene is a thermoplastic material

with a high softening temperature and

good elasticity and mechanical resistance.

During production, PP is mixed with varying

amounts of inert fillers, normally of

mineral origin, each one affecting the

resistance of the finished product. In

particular, it is the shape of the particles of

the fillers that determines the mechanical

resistance of the PP: spheroid calcium

carbonate provides poor resistance; flake-

shaped talc provides a higher resistance

than calcium carbonate. For instance, the

PP used in the car component industry is

almost all made of talc, since this type of

PP is subject to strict EU regulations on

impact strength (resilience) and must not

break into splinters (natural or synthetic

rubber is also added to make the product

more elastic).

Calcium carbonate is used as filler only for

rigid and less resistant materials, such as

interior decoration, packaging films, crates

(for fish, fruits, mineral water, etc.).

The properties and calcium carbonate

content used in PP with a comparatively

low mechanical resistance depend on the

finished product for which they are

intended.


The CaCO3 used to produce packaging films

must have a very small particle size (less

than 2 microns) and a filler percentage of

30-40 %, while that used to produce

packages can have slightly larger particles

(under 10 microns) and a filler percentage

up to about 60 %.

Polyvinyl chloride (PVC)

Polyvinyl chloride is a very common

thermoplastic resin used mainly in two

forms: rigid or flexible. Rigid PVC is used in

hydraulics (pipes, downspouts, autoclaves,

etc.), electrical engineering and electro-

mechanic applications (pump rotors, fans,

pipes and control boards for electric units,

etc.). Flexible PVC is used to make sheets

and rolls for sheaths and waterproofing

cloths or insulating sheaths for cables.

CaCO3 is largely used as a filler to produce

PVC, not to provide the filled material with

any special property, but just to save on

the cost of the raw materials and because

it has a better tolerance to impurities than

PP. Once again, the particle size depends

on the finished product, although its upper

limit remains 40 microns. Particle sizes of

less than 2 microns must be 20 % for belt

or strip PVC and between 50 % and 90 %

for wire insulators.

Plastic fillers (for PP) - Sludge compatibility

Calcareous sludge could be used in this

sector provided that their properties are

adjusted to decrease humidity to no more

than 0.1 % of their weight (very dry

sludge). Magnesium would cause no

problems, while the iron content should be

very low to avoid oxidative catalytic

processes, especially in the PP used to

produce packaging films or when

appearance is of concern (white), but it

would be less important in the production

of rougher materials (crates).

In any case, particle size may be a problem

since it could be reduced by grinding and

sifting.

Plastic fillers (for PVC) - Sludge

compatibility

Sludge made of marble alone seems to

have the right formulation, while its

particle size must be reduced to optimum

values just like its humidity content that

must not exceed approximately 0.1 %.

Special treatments are therefore required,

such as grinding and forced drying.

Remarkable amounts can be used, since

PVC can be filled with remarkable amounts

of inert materials (as much as 60 %).

Neutralization of acidic farmlands

Calcium by-products (calcium carbonate

CaCO3, quick lime CaO, slaked lime or

calcium hydroxide Ca(OH)2 ) are largely

used to correct the acidity of excessively

acidic farmlands. In particular, acidic soils

have a pH of 3-3.5, while alkaline ones

have a pH of 9-10. Acidity depends on the

presence of peat soils (formed in

previously marshy or swampy areas) rich in

humus acids or on the rainwater leaching

the soil for a long time. Normally,

correction involves soils with an acidity

level equal to a pH of 4.5 since lower pH

values would require different crops. For

instance, potatoes, tomatoes, corn, etc.

grow well in poorly acidic soils while other

crops, for instance alfalfa etc., need poorly

alkaline soils.


One can easily argue that calcium

carbonate is much slower in reducing

acidity than other correcting agents (CaO,

Ca(OH)2 ). The amounts to be used depend

on the acidity level and on the crop, but

the mean value can be estimated in

approximately 5 tons CaCO3 per hectare at

regular intervals (about once every 4-5

years) since the soil tends to return to its

initial pH.

Neutralization of acidic soils - Sludge

compatibility

When using marble sludge, coloured

sludge can also be used and the particle

size of such sludge seems to be fit for the

process. There are restrictions, of course,

on the content of heavy metals, which

must be equal to or lower than that

allowed for farming fertilisers. Sludge could

therefore be directly used without having

to be filter pressed or ground into chips.

Sludge could perhaps also be used as “a

slurry” (i.e. containing high amounts of

water) and directly poured onto the soil,

having been carefully raked beforehand.

There are problems, however, with the

competition of other correcting agents

(which have a quicker reaction time) and

with transport since there are not many

acidic soils in Italy and shipping these

agents to other countries (especially

subtropical countries, where acidic soils are

widespread) would be simply too

expensive.

Production of fertilisers

Calcium nitrate Ca(NO3)2 is commonly used

as a fertiliser (Davini, 1998) in farming as a

source of calcium and nitrogen and is

usually made by direct reaction between a

solution of nitric acid and solid calcium

carbonate, as follows:

CaCO3 + 2HNO3 = Ca(NO3)2 + CO2 + H2O

To speed up this heterogeneous reaction,

the contact between the reagents should

be facilitated, so the calcium carbonate

(which is generally made of adequately

ground quarry limestone) should have a

fairly low, particle size. It could therefore

be profitably replaced with marble sludge.

Fertilisers - Sludge compatibility

The particle size of these sludge seems to

be fine enough (under 300 microns) for the

intended use, and the humidity content of

filter pressed materials should not cause

any problem since the above reaction takes

place in the aqueous state (but the use of

thinner materials is not recommended, not

to dilute the nitric acid solution too much).

The usual problem remains, i.e. the high

metal content that should not exceed the

limits imposed on fertilisers, and transport.

The latter seems to be the more restrictive

one.

Desulphurisation of fumes from

thermoelectric plants

Modern society needs more and more

energy to keep developing. This is largely

produced by the combustion of fossil fuels

(coal, fuel oil, etc.) in high-power

thermoelectric plants. However, such

combustion processes also produce high

amounts of sulphur oxides (SOx) which

tend to be quite quickly transformed by

oxidation into SO3 and therefore into

sulphuric acid H2SO4. Sulphuric acid is very

harmful both to our health and to our


environment. It causes remarkable

environmental damage even from a

distance, for example "acid rain", which

damages the crops and forests and causes

irreparable damage to city monuments and

urban structures. We should consider that,

in the open air, all marble work (statues,

friezes, bas-reliefs, etc.) is transformed

from calcium carbonate into calcium

sulphate which crumbles easily and hence

destroys the work over time.

To control these problems, strict law

regulations have been enforced, limiting

the amount of SOx that can be let out

during combustion. Such pollutants are

reduced by using fuels with a low sulphur

content but it is economically unfeasible to

reduce such content to less than a given

percentage, so the waste gases produced

by combustion are adequately submitted

to the so-called fume desulphurisation

process. The "desulphuriser" used in this

case is pure CaCO3 or CaCO3 transformed

into CaO or calcined and then hydrated

into Ca(OH)2. The SOx reducing processes

can then be either “dry” or “wet”.

In “dry processes”, the calcareous dust

comes into contact with the SOx through

injection into the fume manifold at a high

temperature [7,8]. In these conditions, the

CaCO3 is effective against SO3 (of which

there are generally small amounts) and

much less effective against SO2 (of which

there are much higher amounts). To

remove satisfactory amounts of both SO2

and SO3, CaO (or better Ca(OH)2) should be

injected, which, under the effect of heat,

turn into a variant of CaO showing a large

surface area and is therefore highly

reactive. Overall, the reaction is as follows:

CaO + SO2 + ½ O2 = CaSO4

and is made quicker by traces of metal

oxides (such as Fe2O3, etc.). This

technology has some shortcomings, since:

a) the short contact time can prevent the

complete removal of SOx, b) the heat

exchangers could become soiled, thereby

reducing the overall performance of the

plant, and c) there may be problems with

the removal of the solid particulate of the

fumes.

If a solid fuel such as coal is used, the

desulphurisation of waste gases simply

starts in the combustion chamber where

coal is burnt in fluid bed systems after

having being mixed with limestone. In this

process, CaCO3 is calcined into CaO which

then reacts with SO2 and O2, thus forming

calcium sulphate (as described above) with

a reduction of more than 90% with coal

containing approximately 1 % sulphur.

In “wet processes”, combustion fumes

come into contact, in special absorption

towers, with an aqueous suspension of

lime or limestone. Such processes have a

high efficiency, removing over 95 % SOx

and using a high amount of reagents, but

they cause problems with the cooling of

the gases (to approximately 55°C) and with

the load losses caused by the “scrubbing”

process. In addition, other problems are

related to the production of high amounts

of calcium sulphate sludge (plus

combustion ashes). In particular, a number

of “wet” plants have been built that use

suspensions of calcareous materials (that,

for the sake of brevity, we will not describe

in detail), but in any case the disposal of

large amounts of calcium sulphate, which,

because of the low cost of the pure


material, cannot always be sold as

gypseous material, is something of a

problem.

Wet processes” utilise a CaCO3 suspension,

and so the humidity level of the sludge is

not a problem. But they must contain high

amounts of CaCO3 (90-95 %). Impurities are

not a problem, but iron by-products can act

as catalysts in the subsequent oxidation of

sulphite into sulphate. Their particle size

should however be checked to obtain

stable suspensions of calcareous materials.

The consumption of calcareous sludge that

could be used in this industry seems

promising in terms of amounts and

because no selection is required between

pure white marble and slightly coloured

marble.

Production of animal food

Calcium carbonate is one of the most

essential components of animal food, of

which it makes up 7 to 10 %. Of course, it

must contain no heavy metals, have a

suitable particle size and an adequate

humidity content. In particular, it can be

used as a “ventilated product” when the

grain size is smaller than 0.35 mm or as

“pellets” when the grain size is smaller

than 1-2 mm. When producing animal

feed, the “ventilated product” and the

“pellets” are often used with a mean ratio

of 1:2. In addition, the calcium content

must be at least 38% and it must not

contain any toxic substance, and for the

pneumatic batching and handling

equipment to work properly its humidity

should be very low. At present, the

limestone used by foodstuff factories

comes from quarries of white minerals

ground to the required grain size.

Animal food - Sludge compatibility

Sludge made of selected white marble

could partly replace quarry products. This

would involve, however, the production of

dry materials, checking them for purity and

low metal pollutants and perhaps also

overcoming the mistrust of end-users who

would not look favourably upon using

industrial waste to feed animals intended

for human consumption (especially after

the recent events associated with BSE).

Recovery of lead from flat batteries

The recovery of lead from car batteries

involves the use of Solvay soda (sodium

carbonate) as a flux. However, soda can be

replaced with marble dust (calcium

carbonate) resulting from the cutting

process, and the benefits here are basically

two - the reduction of production costs and

the use of scraps in a new production cycle

(Davini, 1998, Belardi, 1998). Due to the

presence of calcium carbonate mixed with

other fillers (silica sand, iron shavings, coal

and lead compounds from the batteries

(basically, lead sulphate and lead oxides),

lead can be recovered while producing

scraps that contain calcium oxide, silicates,

iron oxides and metallic iron, and

approximately 2-3 % lead. When sodium

carbonate was used, the scraps contained

soda and so were unusable and had to be

disposed of in dumping grounds for toxic

and hazardous waste. However, now that

calcium carbonate is used, the scraps

contain lime, which does not prevent its

chemical inactivation by the addition of

Portland cement, sand and a special

additive that prevents surface rust forming


on products made with a vibrating press. In

this way, a toxic product is turned into a

finished product fit for the electric

appliance industry since blocks can be

produced that (containing approximately

50 % iron) have a high specific gravity and

can therefore be used to produce padding

for stabilising the racks of washing

machines.

Recovery of lead from flat batteries -

Sludge compatibility

Marble sludge is suitable for this

application. The only problem is that the

heat treatments required by the

manufacturing process need higher

temperatures, which involve therefore

higher energy consumption.

Production of Solvay soda

In this process, calcium carbonate is the

basic reagent. It is calcined at

approximately 1000 °C, thereby

dissociating as follows:

CaCO3 = CaO + CO2.

Then, CO2 with water, NH3 and NaCl causes

sodium bicarbonate NaHCO3 to precipitate

and, by heating at approximately 200 °C, to

produce sodium carbonate as follows:

2NaHCO3 = Na2CO3 + CO2 + H2O

which is the end-product. The initial

calcium oxide CaO is slaked through its

reaction with water and restores the

ammonia by producing calcium chloride

CaCl2 (used as an anti-ice salt, to be poured

on roads in winter). Overall, the reaction

obtained from all the intermediate steps

can be summarised as follows:

CaCO3 + 2NaCl = Na2CO3 + CaCl2.

Production of Solvay soda - Sludge

compatibility

In theory, the use of white marble sludge is

viable since its formulation is similar to that

of usual materials: CaCO3 % = 90-99 %;

MgCO3 % = 0-6 %, Fe2O3-SiO2-Al2O3 % = 0-3

%. But the formulation should be constant

over time to avoid problems with the

plants. The only real problem is the fact

that calcined limestone is usually 10-15 cm

in diameter, and so the sludge should be

compressed first (maybe into pellets or

briquettes). Humidity could be removed by

these operations or during calcination.

Heavy dimensional treatments are

however required but the usable amounts

would be very high.

Iron and steel manufacture

Iron and steel materials are manufactured

in two steps: a) production of cast iron in a

blast furnace, b) refining or conversion of

the resulting cast iron.

In the blast furnace, iron minerals

(generally iron oxides) are heated along

with a reducing agent (metallurgic coke) at

a high temperature to transform iron

oxides into metallic iron (cast iron). In

addition, flux (limestone) is added for an

easier smelting of the gangue and

combustion ashes, thereby forming scraps

or slag. In the converter, the resulting cast

iron is converted into steel by hot

decarbonisation, a process in which

suitable gas mixtures are blown in to

remove part of the carbon. Once again,

fluxes, i.e. limestone, are added to remove

other unwanted components in the form

of scraps (lead, silica, sulphur, etc.).


Iron and steel manufacture - Sludge

compatibility

The chemical composition of marble sludge

is compatible with that of the flux, while its

particle size and humidity content (which

should be low) are not suitable. Calcareous

sludge should be submitted to adequate

treatments.

6. Case Studies

Pigments and fillers used in the paper

industry

Only white marble sludge is used in the

paper industry because of the very specific

requirements of paper. For these

applications, sludge is first collected by

specialist companies (for instance Cages,

based in Massa, Italy) that store them on

large yards and select them by type and

colour with mechanical shovels. If they do

not meet the required standards, they are

set aside for other applications.

Later on, the sludge that meets the

whiteness requirements is conveyed to a

processing centre, where they are

adequately ground by ceramic balls into

the required particle size. The product thus

ground is then sifted, and the particles (60

%-90 % of the particles must be smaller

than 2 microns and 100 % absolutely

smaller than 50 microns) are mixed with

anionic polyacrylic dispersants, thus

obtaining fairly stable suspensions that are

stored in large silos from which they are

sent to the paper mills.

For instance, Ti.Elle company, based in

Massa (Italy), uses (with its own patented

technology) approximately 50,000

tons/year of white marble dust from

Carrara (containing approximately 22 %

humidity) to be used in the paper industry,

of which approximately 10,000 tons (60 %

smaller than 2 microns and the rest smaller

than 50 microns) to be used as fillers,

approximately 25,000 tons (75 % smaller

than 2 microns and the rest smaller than

50 microns) to be used as pre-coating

agents and approximately 15,000 tons (90

% smaller than 2 microns and the rest

smaller than 50 microns) to be used as

coating agents proper. Usually, the

suspension has approximately 70 % dry

contents.

The quality of the products manufactured

by such technology seems so high and

competitive that the demand largely

exceeds the supply of white sludge from

the Apuan-Versilian area.

Neutralisation of acidic by-products

Calcareous sludge that is not perfectly

white (because they come from the

processing of veined marble or because

they have not been perfectly selected by

the marble processing shops) is loaded on

big covered trucks and sent to Scarlino

(Grosseto), where it is used to neutralise

the sulphuric acid by-products produced by

Societa’ Tioxide in its plants, that produce

titanium dioxide. The reaction produces

CaSO4, a gypseous material (also called

‘chemical gypsum’), by precipitation, as

follows:

CaCO3 + H2SO4 = CaSO4 + CO2 + H2O

Which is reused in the building industry.


The amounts used for the purpose are very

high: over 200,000 tons/year of calcareous

sludge, and once again the demand often

exceeds the supply (especially when, at the

peak of summer, marble processing is

reduced).

There is however the problem of having to

handle and transport the sludge to their

destination and the fact that the trucks

usually come back empty, which heavily

increases costs.

Desulphurisation of waste gas

Calcareous sludge that cannot be reused

even to neutralise acidic by-products can

be used for instance to desulphurise the

fumes produced by high-power

thermoelectric plants. Approximately 3,000

tons have recently been shipped to a 600

MW coal-fed thermoelectric plant owned

by ENEL and situated at La Spezia

(approximately 20 kilometres from

Carrara), to be used in the desulphurisation

of combustion fumes by scrubbing at

approximately 55 °C. The consumption of

sludge with a dry content of about 15 %

depends on the sulphur content of the fuel

(nominally below 1% but in fact between

0.6 % and 0.8 %). The calcium sulphate

produced by scrubbing is filtered to

produce a product with 6-7 % humidity,

which is sold to cement factories,

plasterboard factories, etc.

The preliminary findings look very

promising and encouraging, so much so

that it has been planned to extend this

treatment to more thermoelectric plants,

such as the one in Vado Ligure, in the

province of Savona, much farther from

Carrara (over 160 kilometres).

Recovery of lead from car batteries

There have been similar experiences in the

past. A company based near La Spezia used

to collect and use calcareous sludge for the

purpose (for a detailed description of the

process, see above), to produce lead and

high-density blocks for stabilising the racks

of washing machines. It is said that, by

recycling approximately 800 tons/month of

battery lead, approximately 150 tons of

marble dust were consumed, thus

producing approximately 2,000 self-locking

blocks a day. Unfortunately, the company

is closed down and so there is no other

such consumption or information.

A new technology of marble slurry

waste utilization in roads

Marble slurry dust (MSD, a waste of marble

industry, finds bulk utilization potential in

roads. This study indicates that besides

embankment construction with this waste,

20-30% of soil can be replaced by MSD for

sub-grade preparation. Technology has

been validated by taking full scale trials in

the field.

Recycling of Natural Stone Wastes

Enriched in Calcium and Lithium for

the Manufacture of New Glass

Ceramics and Glazes

Recycling of mine and natural stone wastes

is a demonstrated necessity for protection

of environment (Lottermoser, 2011), as

well as the recovering of quarries. A

natural stone from the cutting and

machining of spanish marble factory has

been used for obtaining new composition

of glasses and glassceramics. After total

physico- chemical characterization of this


enriched calcium waste and evaluation of

its production it is proposed the recycling

in the ceramics and glass ceramics

industries. Thus, for compositional and

processing design of these new vitreous

materials it has been used a lepidolite

powder from the exploitation of a

pegmatite in the Portuguese- Spanish

boundary geological region. The original

vitreous material was full characterized by:

XRF analysis, SEM /EDS analysis including

the microstructure observation, thermal

transformations by DTA/ TG and thermal

behavior under HSM (hot stage

microscopy). The nucleation and crystal

growth mechanisms in these glasses has

been evaluated from bulk and powdered

compositions and final mechanical

properties determined by indentation

methods. The capability for producing

glaze covering for porcelainized stoneware

and conventional fast firing tiles has been

also evaluated. Finally, initial

microstructure by SEM and some initial

results on mechanical properties have

been carried out for knowing the relative

glass ceramic nature of selected obtained

materials from Portuguese and Spanish

lepidolites from pegmatite exploitations

and dolomite/calcite natural rocks.

Utilization of Marble Powder Residue

in Paper Industry

The marble has been commonly used as a

building material since ancient times.

Disposal of the marble powder material the

marble industry, consisting of very fine

powder, is one of the environmental

problems worldwide today but rich in

calcium and magnesium carbonates. In this

study, recovery of carbonate from residue

of marble by flotation was studied,

because concentrated calcium carbonate is

utilized in the paper industry as coatings

but SiO2 and Fe2O3 tenors should be

inferior to 1%. A carbonate concentrate in

residue containing 10.5% SiO2 and 8.7%

Fe2O3 was obtained from a feed

containing 0.49% SiO2 and 0.81% Fe2O3

with an overall recovery of 96% by weight.

7. Discussion and Conclusions

The analysis of the potential uses for the

slurries as raw materials for secondary

industries has shown that those products,

after processes of characterization and

valorisation (in same cases), could be

suitable for substituting the conventional

micronized carbonates, which are

nowadays used in the industry. Many

applications have been detected and

analysis considering the advantages and

the compatibility showing that these

residues could be a potential raw material

eliminating the current problems of

pouring and storage in dumps.

Due to the strict restriction for some

applications, as for example the pharmacy

industry, as well as the expected

demanded volumes, it was concluded that

the most suitable applications are those

where the requirements for the raw

material are not so strict and the

demanded volume could be very important

such as cement and concrete industry,

structural ceramics, agglomerated stone

and other added value applications (paints

and papers industries). It will be also


intended to perform tests for the

production of limes and Precipitated

Calcium Carbonate.


8. References and

bibliography related to the

recycling of slurries

This deliverable has been done considering

all the previous works and studies

performed by researchers in this topic.

Some of those works are general studies to

find solutions for the recycling whereas

other studies are very concrete studies

where some tests at laboratory scale have

been performed to determinate the

feasibility of the incorporation of slurries as

raw materials to be used in other

applications. The following table shows the

most relevant works in the treated topics

during last decades.


Author (s) Year Title Book/Journal/Proceedings

- (2011)

IL RICICLO DI TERRE DA SCAVO DIM GROUP BREVETTATA UNA TECNOLOGIA INNOVATIVA PER IL RECUPERO E LA STABILIZZAZIONE CON MISCELE DI LEGANTI MEDIANTE UN’APPOSITA MACCHINA Ambiente, Anno XXII, n° 6, luglio-agosto 2011, pag. 39-41

BRGM (2010)

MANAGEMENT OF MINING, QUARRYING AND ORE-PROCESSING WASTE IN THE EUROPEAN UNION - STUDY MADE FOR DG ENVIRONMENT, EUROPEAN COMMISSION

Regione Emilia Romagna (2004)

GESTIONE DELLE RISORSE NATURALI E DEI RIFIUTI – ATTIVITÀ ESTRATTIVE

Relazione sullo stato dell’Ambiente – Emilia Romagna, 2004

-

ALTA FORMAZIONE E RICERCA IN TEMA DI UTILIZZO DEGLI SCARTI DELL’INDUSTRIA LAPIDEA

Università degli Studi di Napoli Federico II / Dipartimento di Scienze della Terra, AIMM (Associazione Italiana Marmomacchine), ISIM (Istituto Internazionale del Marmo), Universidade Federal de Rio grande do Sul e Universidade Estadual de Feira de Santana

Boda E. (2004)

SUSTAINABLE DEVELOPMENT LNDICATORS FOR THE EU NON-ENERGY EXTRACTIVE INDUSTRY

Consiglio Nazionale delle Ricerche, Iinternational organizing committee of world mining congress, 2004

- (2000)

PROMUOVERE LO SVILUPPO SOSTENIBILE NELL'INDUSTRIA ESTRATTIVA NON ENERGETICA DELL'UE Comunicazione della commissione UE, 2000

- (2006) RIFIUTI DELLE INDUSTRIE ESTRATTIVE Ambiente - 18-01-2006

Directorate-General for Enterprise, European Commission (2004)

SUSTAINABLE DEVELOPMENT INDICATORS FOR THE EU NON-ENERGY EXTRACTIVE INDUSTRY IN 2001

Colombo A, Tunesi A., Barberini V., Galimberti L. (2005)

CARATTERIZZAZIONE CHIMICA E MINERALOGICA DEI FANGHI DI SEGAGIONE

Report finale per INTERREG IIIA - Valorizzazione dei fanghi derivanti dalla lavorazione lapidea

Carraio, Castelli, (2005)

BIORISANAMENTO E POTENZIALITÀ DI IMPIEGO DEL LIMO DI SEGAGIONE NEL SETTORE VERDE


Mancini R., Fornaro M., Dino G.A. (2005)

APPLICAZIONI E TRATTAMENTI IN CAMPO INGEGNERISTICO E INDUSTRIALE


Accati E., Assone S. (2005)

APPLICAZIONI IN CAMPO AGRICOLO ED AMBIENTALE


- (2005) ANALISI ECONOMICA DEI COSTI DI SMALTIMENTO

USI- Locarno, Report finale per INTERREG IIIA - Valorizzazione dei fanghi derivanti dalla lavorazione lapidea

- (2004)

BEST PRACTICES OF THE NATURAL STONE INDUSTRY SOLID WASTE MANAGEMENT AT THE QUARRY AND FABRICATION FACILITY University of Tennessee Center for Clean Products, 2004

Provincia di Verona

LA LAVORAZIONE DEI MATERIALI LAPIDEI – RAPPORTO SULLO STATO DELL’AMBIENTE DELLA PROVINCIA DI VERONA Technical report

- (2011)

I FUMI DESOLFORATI. I GRANDI IMPIANTI DI COMBUSTIONE USANO SISTEMI NON RIGENERATIVI AD UMIDO, CON CALCE O CALCAREE Ambiente, Anno XXII, n. 4, maggio 2011, pag. 11-19



- (2011)

L’ESSICAMENTO ALTERNATIVO. TRE I METODI POSSIBILI, TRA CUI L’USO DI BIOMASSE COME COMBUSTIBILE, INCLUSE LE STESSE MELME ESSICATE Ambiente, Anno XXII, n° 8, ottobre 2011, pag. 22-23

- (2011) L’ECO-PRODUZIONE DEL CEMENTO Ambiente, Anno XXII, n° 6, luglio-agosto 2011, pag. 39-41

-

PROPOSTA PER IL TRATTAMENTO E VALORIZZAZIONE DEI PRODOTTI DI RISULTA DELLA LAVORAZIONE DEI MATERIALI LAPIDEI COME ELEMENTO QUALIFICANTE DEL RISANAMENTO AMBIENTALE DEL COMPRENSORIO LIGURE APRANO VERSILIESE Termomeccanica italiana

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WASTE FROM QUARRYING AND PROCESSING IN THE DIMENSIONAL STONE SECTOR: STATE OF ART Technical report

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IMPIANTO DI ESSICAZIONE FANGHI DI GRANITO IN USCITA DA FILTROPRESSA CON CAPACITÀ PRODUTTIVA DI 20 T/H UMIDITÀ ENTRATA 202-25%, UMIDITÀ USCITA 0,5% Technical proposal

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POSSIBILITÀ DI IMPIEGO IN AGRICOLTURA DI MATERIALI INERTI A BASSA GRANULOMETRIA

Dipartimento di Agronomia e Gestione dell'Agroecossitema, Università di Pisa



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A NEW TECHNOLOGY OF MARBLE SLURRY WASTE UTILISATION IN ROAD

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Sampat Lal Surana

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THE RECURRENCE OF STONE PROCESSING WASTE SLURRY USING TECHNOLOGY http://www.estone.cc/

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UTILIZATION OF MARBLE AND GRANITE WASTE IN CONCRETE BRICKS

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FLEXURAL STRENGTH AND CREEP CHARACTERISTIC OF TILES CONTAINING MARBLE POWDER

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EFFECT OF USING STONE CUTTING WASTE ON THE COMPRESSION STRENGTH AND SLUMP CHARACTERISTICS OF CONCRETE

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RECOVERY AND REUSE OF MARBLE POWDER BY-PRODUCT Global Stone Congress 2010

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ASSESSMENT OF SHORT-TERM LEACH BEHAVIOR OF WASTE NATURAL STONE SLURRIES MIXED INTO SOILS IN ROAD AND EARTH CONSTRUCTION

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- 1999

DEVELOPMENT AND IMPLEMENTATION OF A PILOT UNIT TO RECOVER SOLID WASTES AND SLUDGES FROM THE MARBLE INDUSTRY Technical report

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Documents

Guideline of possible application of slurries in industries demanding micronized materials and valor