Iron Ore Technical Working Group Submission for …ironorefines-twg.com/wp-content/uploads/2013/07/TWG_IOF... · Web viewThe ASTM D698-07 describes a standard test method for laboratory

Iron Ore Technical Working Group

Submission for Evaluation and

Verification

Iron Ore Fines Proctor-Fagerberg Test

“Consider the adequacy of current methods for determining

transportable moisture limit (TML) for iron ore fines and consider new

and/or amended existing methods to be included in Appendix 2 of the

IMSBC Code.”

May 2013

All participants of the TWG operate under the international and their respective national antitrust laws and regulations. Suitable controls are in place to ensure all meetings are

minuted and discussions and material exchanged do not transgress anti-trust requirements. All participants of the Technical Working Group have access to in-house

competition law advice, operate at all times under all applicable international and national competition laws and regulations and have been cautioned accordingly.

Preamble

At the 17th session of the Sub-committee on Dangerous Goods, Solid Cargoes and Containers, Member States directed the Correspondence Group (CG) on the transportation of the iron ore fines (established at DSC 16) to continue its work with updated Terms of Reference to:

.1) consider the adequacy of current methods for determining transportable moisture limit (TML) for iron ore fines and consider new and/or amended existing methods to be included in appendix 2 of the IMSBC Code – to be completed by end of May 2013 (DSC 17/4/34 and DSC 17/INF.9);

.2) consider the evaluated and verified research into Iron Ore Fines – to be completed by end of May 2013;

.3) prepare draft individual schedule(s) for iron ore fines and any required amendments to appendix 2, taking into account .1 and .2 above and review the existing iron ore schedule, as necessary; and

.4) submit a report to DSC 18.

In an effort to ensure the CG’s deliberations are informed by the latest scientific insights, the three largest iron ore producers (with the support of their respective Competent Authorities) committed to form an Iron Ore Technical Working Group (TWG). The TWG is coordinating research efforts into the transportation of iron ore fines to provide independently “evaluated and verified” findings that can serve as the basis for decision making.

To this end, the TWG will produce the following reports:

• Report #1: “Terms of Reference .1” – This report assesses the adequacy of current IMSBC Code methods for determining the Transportable Moisture Limit (TML) of Iron Ore Fines (IOF).

• Report #2: “Marine Studies” – This document reports the characteristics of vessel motions and forces imposed on IOF cargoes during transit; the impacts of vessel size and sea conditions (swell, sea and wind); and, the stability of vessels in various cargo behaviour scenarios.

• Report #3: “Routine Test Method”– Building on the outcomes of Report #1, this document explores potential adjustments to one of the existing routine IOF test methods – or a new test – to better reflect actual in-hold shipping conditions and observations.

• Report #4: “Reference Tests” – This report provides further evidence to substantiate the applicability of the routine IOF test method identified in Report #3 through the material’s performance in real-world conditions using a variety of well-established geotechnical methods, numerical modelling and cargo observation.

• Report #5: “Final Submission” – This report will integrate the results of all of the preceding research into a series of recommendations that can inform the deliberations of the Correspondence Group.

8-May-23 Page 2 of 60

The TWG have appointed external experts (Prof Kenji Ishihara, Prof Junichi Koseki and Dr Kourosh Koushan) in the relevant disciplines to verify each of the reports. This evaluation is followed by an independent scientific review process undertaken by Imperial College London (Dr Stephen Neethling and Professor Velisa Vesovic) and for vessel stability (Marine Report) by University of Strathclyde (Professor Dracos Vassalos) under the direction of the International Group of P&I Clubs (IG). IG represents a group of industry NGOs that includes BIMCO, Intercargo, International Chamber of Shipping and IFAN. The finalized reports are then submitted to the CG, fulfilling the requirement for “evaluated and verified” research.


Executive summary

The Technical Working Group (TWG), comprising one Brazilian and two Australian mining companies,

had previously undertaken a literature review and conducted extensive research into the suitability of

the current methods outlined in the International Maritime Solid Bulk Cargoes Code (IMSBC) for

determining the Transportable Moisture Limit (TML) for Iron Ore Fines (IOF). Since the IOF products

being tested are both physically and metallurgically different from the metal ore concentrates and coal

products described in the IMSBC Code, the TML tests outlined are not the most appropriate for the

testing of IOF.

Based on the previous results of in the TOR1 report, it was concluded that the Proctor-Fagerberg Test

(PFT) is better suited and technically more appropriate for determining the TML for IOF. The premise

of this test is that the compaction energy used will create similar densities for given moisture contents

as will be found in a ship hold. The compaction energy, applied by varying degrees of hammer weight,

drop height and number of drops per layer, is stipulated in the IMSBC Code and based on

Fagerberg’s research completed in 1965. The compaction energy used for the PFT needs to be

updated to better reflect actual in-hold shipping conditions and observations. Therefore, a study has

been undertaken to develop a modified PFT procedure using actual in-hold cargo density and

moisture content information.

The key findings of the research are:

The Proctor-Fagerberg test is an internationally recognised test that is suitable for determining the

compaction curves of various materials, based on their degree of saturation (IMSBC Code, 2012).

Actual ship hold observations for IOF do not match the dry density and void ratio values obtained

by using Fagerberg’s Proctor C hammer that is currently stipulated in the code.

There are numerous methods available to determine cargo in-hold densities, such as

internationally recognised laboratory tests, laser scanning, cargo observations, Cone Penetration

Tests and Drop Tower Tests.

It is important that the Specific Gravity (SG) is measured as accurately as possible as small

deviations in the SG value can influence the compaction curves and saturation lines determined

in the PFT. The determination of SG should be done with a recognised international or national

standard.

It is common across all PFT methods (A-E) to use twenty-five hammer drops per layer and that

the mould is filled in five distinct layers. The large number of hammer drops gives a more uniform

density in the mould that is more repeatable between tests. Energy input can be changed by

varying the weight of the hammer and the height of the drop.


As is consistent with Fagerberg’s original work, it was found that twenty-five drops per layer using

five layers per test was most suited for IOF. This was proven using Proctor-Fagerberg Method C

and Proctor-Fagerberg Method D.

The dry density and void ratio values determined from the Proctor-Fagerberg D hammer display

the closest alignment to the dry density and void ratio values measured from actual in-hold ship

conditions for the IOF material tested in this study.

Past studies by Fagerberg indicated that the TML is determined from the Optimum Moisture

Compaction (OMC), which occurred at approximately 75% saturation for Scandinavian ores and

concentrates. The OMC however, for the IOF tested in this study, occurs between 90-95%

saturation. It is therefore deemed that using a saturation of 80% for the determination of the TML

is suitable for IOF. This provides a larger degree of safety to what is proposed in Fagerberg’s

original work.

Variations to the current method outlined in the IMSBC Code (i.e. changing hammer drops/layer,

hammer drop height and hammer weight) found that variable compaction energies that are

applied to the material influence the material dry density. Whilst it is possible to change multiple

parameters, changing the hammer weight alone provides conservative results for all IOF tested.

The 150 g and 15 cm drop Proctor-Fagerberg D hammer is the most representative of actual in-

hold material cargo observations for IOF.

It is concluded therefore, that the TML for IOF is best determined by using the PFT D method and

the moisture corresponding to the point where this compaction curve intersects the 80%

saturation line.

The procedure used for the IOF PFT D method is outlined in the Appendix A2 of this report.


Table of Contents1 Proctor-Fagerberg Review and Void Ratio Calculations..............................................................11

1.1 Proctor-Fagerberg Test Review...........................................................................................11

1.2 Void Ratio Calculations........................................................................................................16

1.3 Bulk Density Determination..................................................................................................17

1.3.1 Australia-A dry density determination...........................................................................18

1.3.2 Australia-B dry density determination...........................................................................21

1.3.3 Brazilian dry density determination..............................................................................23

1.4 Determination of Specific Gravity (SG) and the effect on TML.............................................25

1.4.1 Australia –A.................................................................................................................. 25

1.4.2 Australia –B.................................................................................................................. 26

1.4.3 Brazil............................................................................................................................ 28

2 Key Findings - TWG Research on Proctor-Fagerberg Test Development...................................28

2.1 The Optimum Moisture Compaction (OMC) point for the IOF tested occurs between 90-95% saturation......................................................................................................................................... 28

2.1.1 Australia -A................................................................................................................... 29

2.1.2 Australia –B.................................................................................................................. 30

2.1.3 Brazil............................................................................................................................ 31

2.2 Variations in applied compaction energy have a first order impact on the dry density of IOF material............................................................................................................................................ 32

2.2.1 Varying number of hammer drops per layer directly impacts the dry density of the IOF material. 32

2.2.2 Varying the hammer drop height directly impacts the dry density of the IOF material..36

2.2.3 Dry density (t/m3) vs. compaction energy (kJ/m3).........................................................39

2.3 Compaction energies generated with the Method C hammer for Iron Ore Fines are excessive......................................................................................................................................... 40

2.3.1 The key findings from this test work are:......................................................................41

2.3.2 Australia – A................................................................................................................. 42

2.3.3 Australia – B................................................................................................................. 45

2.3.4 Brazil............................................................................................................................ 46

2.4 Proctor-Fagerberg D precision is deemed satisfactory when a testing method is consistently applied............................................................................................................................................. 47

2.5 Removal of large particles from the IOF testing samples is recommended for assuring proper levelling of the sample in relation to the brim of the Proctor-Fagerberg mould.....................48

3 Conclusions................................................................................................................................. 50

Appendix – A1..................................................................................................................................... 52

Void Ratio Calculations:...................................................................................................................52


Energy Calculations:........................................................................................................................ 55

Appendix – A2..................................................................................................................................... 56

List of Figures

Figure 1: Various compaction curves using Proctor apparatus using Fagerberg’s Methods A-E (Fagerberg ,1965)................................................................................................................................ 12Figure 2: Testing apparatus.................................................................................................................13Figure 3: Compaction curves for magnetite concentrate using Method C and Method D and compared to actual ship cargo measurements from Fagerberg, 1965.................................................................14Figure 4: PFT for an Ilmenite Concentrate demonstrating the OMC at 70% Saturation using a Proctor C hammer............................................................................................................................................ 15Figure 5: Air, water and solids phase diagram.....................................................................................16Figure 6: Cargo observed after loading (left) and before discharge (right)..........................................19Figure 7: Quarterly dry bulk density.....................................................................................................21Figure 8: Cargo density by laser scanning...........................................................................................22Figure 9: Volume change / compaction due to voyage undertaken in Q13..........................................22Figure 10: Equipment used in CPT on top of the cargo.......................................................................24Figure 11: Laser scan image inside a Brazilian IOF cargo hold of a Capesize Vessel........................24Figure 12: Effect of sample pulverisation on helium pycnometry.........................................................27Figure 13: Effect of SG on TML...........................................................................................................27Figure 14: results for Australia-A D1 sample shows the OMC exceeding 90% saturation...................29Figure 15: Close-up of Figure 9 around the OMC points for Australia-A's IOF material.......................29Figure 16: Australia B Product C PFT results......................................................................................30Figure 17: PFT results for Brazilian IOF material shows the OMC exceeding 90% saturation............31Figure 18: Close-up of Figure 17 around the OMC points for Brazilian IOF material...........................31Figure 19: The effect on the PFT plot with varying number of drops/layer using the 350 g/20 cm hammer for Australia-A D1 ore (Method C).........................................................................................33Figure 20: The effect on the PFT plot when with varying number of drops/layer using the 150 g/15 cm hammer for Australia-A D1 ore (Method D).........................................................................................34Figure 21: Australia B, Product A: Number of hammer drops effect on dry density.............................34Figure 22: Australia B, Product C: Number of hammer drops effect on dry density.............................35Figure 23: Results of compaction tests on two different Brazilian IOF (Sample 1 and Sample 2).......35Figure 24: The effect on dry density by varying the number of hammer drops per layer for Australia A’s D1 material.................................................................................................................................... 36Figure 25: Proctor-Fagerberg compaction curves for Australia-A D1 ore using 150 g hammer at 5cm and 15cm drop height.......................................................................................................................... 37Figure 26: Australia B: Increasing drop height increases dry density..................................................37Figure 27: Proctor-Fagerberg compaction curves are plotted for the same sample of Brazilian IOF using the 350 g hammer at different drop heights with 25 drops per layer..........................................38Figure 28: The standard error associated with varying hammer drop height using dry density values at the as received moisture content. The 150 g hammer with 25 drops per layer has been used with D1, D2 and D3 material.............................................................................................................................. 38Figure 29: The standard error associated with varying hammer drop height using dry density values at the “as received” moisture content. The 350 g hammer with 25 drops per layer has been used with D1, D2 and D3 material.......................................................................................................................39Figure 30: Dry Density (t/m3) vs. Compaction Energy (kJ/m3) for D1, D2 and D3 material.................40Figure 31: PFT plots for determination of hammer selection for D1 ore..............................................42Figure 32: PFT plots for determination of hammer selection for D2 ore..............................................43Figure 33: PFT plots for determination of hammer selection for D3 ore..............................................44Figure 34: Australia B, Product C: PFT C hammer (150 g, 15 cm drop height, 25 drops per layer) provides compaction comparable to loading conditions.......................................................................45


Figure 35: Australia B, Product B: PFT C hammer (150 g, 15 cm drop height, 25 drops per layer) provides compaction comparable to loading conditions.......................................................................45Figure 36: Bulk density compaction curve using the 350 g, 20 cm hammer (PFT C) with 4 drops per layer..................................................................................................................................................... 46Figure 37: Proctor-Fagerberg plot for ‘Brazilian IOF 1’ using PFT D...................................................46Figure 38: Proctor-Fagerberg plot for ‘Brazilian IOF 2’ using PFT D...................................................47Figure 39: Comparative results of PF tests between an external laboratory and the laboratory of Australian-A......................................................................................................................................... 48Figure 40: PFT precision trial for Australia B Product A.......................................................................48Figure 41: Two pictures illustrating the negative impact on levelling the sample in relation to the brim of the mould in the presence of coarse particles..................................................................................49


List of Tables

Table 1: Variation of Proctor-Fagerberg tests and compaction procedures.........................................12Table 2: Cargo compaction from cargo height measurements............................................................19Table 3: Laser scanning summary of all hold results for cargo bulk density........................................20Table 4: Bulk densities determined by Drop Tower Tests....................................................................20Table 5: Densities and void ratios for Brazilian IOF.............................................................................23Table 6: Australia-A changes in TML with varying SG.........................................................................26Table 7: Influence of different measurements techniques of density of solids on the TML for two different Brazilian IOF samples............................................................................................................28


ABBREVIATIONS

ASTM American Society for Testing and Materials

Cargo intersection The point where the cargo meets the hold wall

Cargo peak The maximum height of the cargo after loading

CPT Cone Penetration Test

Dry bulk density This is the ratio of the dried mass of the material to its volume

DWT Dead Weight Tonnage (of a vessel)

℮ Void ratio on a Proctor-Fagerberg graph

℮v Water content on a Proctor-Fagerberg graph

IMO International Maritime Organization

IMSBC Code International Maritime Solid Bulk Cargo Code

IOF Iron Ore Fines

ISO International Organization for Standardization

OMC Optimum Moisture Compaction

OMP Optimum Moisture Point

PF Proctor-Fagerberg

PFT Proctor-Fagerberg Test

TML Transportable Moisture Limit

TOR Terms of Reference

TWG Technical Working Group

S Saturation degree expressed in percentage

SG Specific Gravity is the ratio of the density of a substance to the density

(mass of the same unit volume) of a reference substance. It is

dimensionless. In the context of the present report, taking density of water

equal to one tonne per cubic meter, the Specific Gravity related to water

becomes numerically equal to the Density of Solids, which is expressed in

units of mass per volume, such as tonnes per cubic meter or grams per

cubic centimetre.

X + X is nominal percent moisture value to allow scalability but preserve


masking of data to fulfil internal anti-trust requirements.

1 PROCTOR-FAGERBERG REVIEW AND VOID RATIO CALCULATIONS.

1.1 Proctor-Fagerberg Test Review

The original Proctor test was developed in the early 1930’s by Ralph R Proctor, and is used

extensively in geotechnical engineering on materials such as sand, silt and clay. This test can be

performed in the laboratory to determine the Optimum Moisture Compaction (OMC) at which a given

material will be at its most dense state. The Proctor test has undergone modifications since then; and

in 1958 the test was modified to become a standard as part of the American Society for Testing and

Materials (ASTM). The ASTM D698-07 describes a standard test method for laboratory compaction

characteristics of soil using a standard effort of 600kN-m/m3.

Fagerberg investigated a modified Proctor Test (which would later become known as the Proctor-

Fagerberg Test) in his 1965 paper “Hazards of shipping granular ore concentrates – part II”. The

simple testing procedure involved compacting material inside a cylindrical mould. The material is filled

in five separate layers, each layer receiving a specified number of drops from a standard weighted

hammer which is dropped from a specified dropping height. The sample is then levelled off along the

brim. The process is repeated for incremental moisture contents until a full compaction curve is

obtained. The weight and moisture content of each test is calculated and a graphical relationship

between dry density to moisture content is plotted to establish a set of compaction curves. Fagerberg

realised that the Proctor compaction test could be useful for determining the stability of bulk cargo

ores and produced five individual tests with varying compaction energies. Materials such as bauxite,

coal and dicalcium phosphate have been tested using this method for the determination of

compaction curves. (Kruszewski, 1985). These tests and their respective variables are described in

and show the compaction energies range from 934 kJ/m3 for the A method to 2.5 kJ/m3 for the E

method.

Depending on the compaction energy used as a function of the testing variables, each test will

produce a different compaction curve as seen in Figure 1. Lower applied energies see the void ratios

increase as a result of less dense compaction of particles in the material. Appendix A1 outlines the

equations used to calculate the Proctor-Fagerberg plots.


Table 1: Variation of Proctor-Fagerberg tests and compaction procedures

Method Weight of

Hammer(g)

Height of

Drop (cm)

Number of

drops per layer

Number of layers Compaction Energy

(kJ/m3)

A 2498 30.5 25 5 934.0

B 1000 20 25 5 245.3

C 350 20 25 5 85.8

D 150 15 25 5 27.6

E 50 4 25 5 2.5

Figure 1: Various compaction curves using Proctor apparatus using Fagerberg’s Methods A-E (Fagerberg ,1965)

The energy input can be described by the following equation:

Energy=No .of drops per layer x No .of layers x Hammer weigh t (N ) x Heigh t of Drop (m)

Volumeof Mold(m3)

One of the key conclusions from Fagerberg was “the investigations show that the upper critical

moisture content (of a material) can be determined accurately and rapidly by compaction tests with

the Proctor apparatus”

Fagerberg performed these above tests on mineral concentrates such as magnetite, un-floated iron

ore concentrates and flotation concentrates which were sampled from the holds of 85 vessels (which

were approximately 10,000 DWT) to get representative samples. It is interesting to note that the


number of drops per layer and the number of layers stayed constant throughout Methods A-E. It was

the weight of the hammer and the height of the drop that determined the variation in compaction

energy applied to the material. The testing apparatus consists of the compaction cylinder and

compaction hammer and can be seen in Figure 2.

Figure 2: Testing apparatus

Fagerberg noted from his test work that upon analysis of the materials within the cargo hold, the

material had undergone the same degree of compaction at the middle and bottom of the cargo. Of

the 85 vessels studied, graphical results showed that it was characteristic of all compaction curves to

have the same general shape and that the minimum point on the curve is defined as the Optimum

Moisture Compaction (OMC). Characteristic of all the concentrate material that Fagerberg studied

using the C hammer, the voids at optimum compaction are filled to 70-75% by volume of water with

the balance constituting air. It is noted that to prevent large quantities of free water, the moisture

should not exceed a 70-75% saturation limit. Figure 3 is an example of a typical compaction curve

from Fagerberg’s studies whereby the OMC occurs between the 70% and 75% saturation lines.

Importantly, the compaction of a concentrate cargo under rough weather and sea conditions lies in the

area “limited by the compaction curves obtained with Method C (350 g / 20 cm drop height) and

Method D (150 g / 15 cm drop height)” as seen in Figure 3. The symbols represent the void ratios

measured at a certain height and sampling point in the cargo heap. In order to match the compaction

curve with the dry density or void ratio values obtained from in-hold cargo measurements, Fagerberg

chose the Method C hammer, taking into account an appropriate safety margin. This produced an

OMC between 70% and 75% saturation.

Australia-B undertook the C Method on an Ilmenite Concentrate to replicate the work that Fagerberg

completed. As can be seen in Figure 4, the OMC occurs at 70% saturation.


Figure 3: Compaction curves for magnetite concentrate using Method C and Method D and compared to actual ship cargo measurements from Fagerberg, 1965


Figure 4: PFT for an Ilmenite Concentrate demonstrating the OMC at 70% Saturation using a Proctor C hammer

Using the PFT C hammer to represent the compaction force which the materials is subject to, it was

found that the upper critical water content was indicated by the moisture at optimum compaction.

Fagerberg deemed that anything below the OMC (the upper critical moisture limit) would be safe to

ship. At this saturation level, the Transportable Moisture Limit (TML) could be determined by reading

the moisture content directly from the compaction curve. Fagerberg noted that at this saturation state,

no “disturbing water segregation” will evolve.

In light of the information above, the compaction characteristics of a material not only depend on the

amount of input energy, but also on particle mineralogy, the spectrum of particle sizes, the shape and

specific gravity. The IOF material in this Terms of Reference 2 report differs from the concentrates

that Fagerberg used in his study, as is evident by the OMC occurring between 90-95% saturation, as

previously described in the TWG’s Terms of Reference 1 Report.


1.2 Void Ratio Calculations

Ore material represents a three-phase system, consisting of solids, air and water. The volume of air,

water and solids are represented as Va, Vw and Vs respectively, whereby the total volume is VT. The

weight of air, water and solids are represented by Wa, Ww and Ws respectively, whereby the weight of

air is equal to zero. The phase diagram is represented below in Figure 5.

Figure 5: Air, water and solids phase diagram

Calculations of void ratio can be seen in the Appendix A1 and have been used by Australia-A to

determine the void ratio that reflects iron ore fines solid density and bulk density. The void ratio equals

the ratio of SG to dry density minus 1 as given in Appendix 2 of the IMSBC Code. Determining the

void ratio of a porous solid is not straight forward and can lead to errors in SG values such that the

solid is represented as both solid and pores. Derivations of the equations below can be found in the

Appendix A1.

The following equation can be used to determine the void ratio on a ‘Saturation vs. Gross H2O’ plot.

Void Ratio, e=WW

1−W Wx SGS

Where :WW=%GrossH2O

100, SG=SpecificGravity∧S=%S

100

Water density , ρW=1( tm3 )Solidsdensity , ρs=ρw( tm3 ) x SG

The equation below can be used to determine the void ratio using PFT data.


Void Ratio, e= SGρdry

−1

Where : ρdry=Dry Density ( tm3 )In order to compare the PF compaction curves to dry density and void ratios for IOF in ship’s cargoes,

bulk density assessments of the ore are performed inside the cargo hold. The bulk density (t/m3) is

defined as the weight of solids, air and water in a known volume. As outlined in the sections below,

cargo observations have been undertaken by the TWG companies and include methodologies and

measurements in relation to cargo behaviour at loading and unloading.

1.3 Bulk Density Determination

The IMSBC Code states that bulk density is the weight of solids, air and water per unit volume and in

general, is expressed as kg/m3. The void spaces within the material may be filled with either air or

water (Item 1.7 Definitions, IMSBC Code). The bulk density of a solid bulk cargo determines its

stowage factor, which according to the IMSBC Code, is a figure which expresses the number of cubic

metres in which one tonne of cargo will occupy, as seen below. The stowage factor is regarded as

mandatory information that should be provided to shippers when declaring cargo. (IMSBC Code,

Section 4.3) whereby stowage factor (expressed in m3/t) = 1 / (bulk density kg/m3/ 1000 kg/t)

Real world bulk densities can be determined as a result of direct measurements of mass and volume.

The assessment of bulk density is routine practice in the Australian and Brazilian iron ore industries.

The average bulk density is assessed under industrial conditions, for example onboard ships, at port

stockyards and cargo spaces. Additionally, the bulk density of a material may be determined under

laboratory conditions after a certain compaction effort has taken place, which is usually confined in

three dimensions and with no tamping force.

There are internationally published standards on bulk density determination, including the circular

issued by IMO, the MSC/Circ.908, dated 4th June 1999: ‘Uniform method of measurement of the

density of bulk cargoes’. There is one internationally recognized standard for specifically assessing

bulk densities of iron ores: ISO 3852 –‘ Iron ores for blast furnace and direct reduction feedstocks –

Determination of bulk density’. Interestingly, a scrutiny of both MSC/Circ.908 and ISO 3852 reveals

that they are basically similar methods to obtain a non compacted bulk density (sometimes referred as

‘natural’ bulk density).

That last statement becomes obvious when examining one step of the procedures described in

MSC/Circ.908: “3.2 The container should be filled with a sample of the material so that it is trimmed

level with the top of the container. The material should not be tamped.” ISO 3852 describes a


procedure in a more in-depth level of detail. This procedure involves filling a metal cylinder, called

‘small container’ (400 mm diameter and 400 mm height – approximately 0.05 m3 inner volume) with

the solid bulk cargo, as loaded, if it is to reflect as loaded conditions. That sample is levelled off along

the brim of the cylinder, and weighed. The bulk density figure results from dividing mass of sample by

its confined volume (the cylinder). The standard also prescribes a pilot-scale method variation with a

“large container” to test samples with a minimum of 10 t of mass.

In order to correlate the PF compaction curves to dry density and void ratios for IOF, bulk density

assessments of the ore are performed inside the cargo hold. As outlined in the sections below, cargo

observations have been undertaken by the TWG companies and include methodologies and

measurements in relation to cargo behaviour at loading and unloading.

The errors for the bulk density determination are due to volumetric survey and conveyor weightometer

measurements. For volumetric measurements the errors range from ~15m3 per hold, equating to

0.5% (Aust A), ~ 50m3 (Aust B) for approx 7000m3 survey of a single capesize vessel hold; ie <0.75%

(absolute) in volume. The weightometer error is about 0.25% (absolute). Moisture determination by

ISO3087 has a precision about 0.22% (absolute) corresponding to a 95% confidence ~0.45%

(absolute) for the moisture result. Combining these yields a 95% confidence limit for the dry density of

<1.5% (absolute). Ie for dry density of 2.2t/m3 error is +/- 0.03t/m3.

1.3.1 Australia-A dry density determination

Over 100 observations of the behaviour of three different IOF materials have been studied by

Australia-A whereby the voyage route typically was from Western Australia to China. The cargo

appearance was visually observed and recorded before loading and after discharge and the height of

the cargo at the hold wall and hatch covers were taken (Figure 6). From these measurements, an

estimation of volume change / reduction (due mainly to compaction, material re-distribution) as a

percentage was made and the results from all 100+ observations can be seen in

. There was no correlation found between volume change and sea conditioning experienced during

the voyage.


Figure 6: Cargo observed after loading (left) and before discharge (right)

Table 2: Cargo compaction from cargo height measurements

Hold Wall - Cargo Intersection Cargo Peak

Compaction % Hold 1 Hold 9 Hold 1 Hold 9

Average 1.9 0.7 3.8 2.6

Maximum 10.2 3.2 10.3 7.3

Minimum 0.0 0.0 0.5 0.1

Additionally, a Leica HDS6200 laser scanner was accurately located inside the ship hold to map the

cargo surface and to provide a profile of the cargo after loading and before discharge. By using

surface profiles to determine the volume of cargo, this allowed for estimations of bulk density and the

degree in which it changed with time, as the mass of ore in the hold is already known from load cells

on the ship conveyor. Validation of volume measurements are confirmed using standard ISO3852-

2007 for uncompacted density tests and standard AS1141.4-1996 for compacted density

determination. The laser scanning results for cargo bulk densities are listed in Table 3.


Table 3: Laser scanning summary of all hold results for cargo bulk density

Iron Ore Fines D1

Iron Ore Fines D2

Iron Ore Fines D3

Laser

Scanning

Initial Bulk

Density

(t/m³)

Final

Bulk

Density

(t/m³)

Initial Bulk

Density

(t/m³)

Final

Bulk

Density

(t/m³)

Initial Bulk

Density

(t/m³)

Final

Bulk

Density

(t/m³)

Average 2.25 2.30 2.00 2.05 1.95 2.0

Maximum 2.28 2.36 2.10 2.16 2.06 2.10

Minimum 2.16 2.20 1.96 2.01 1.90 1.93

NB. The average, maximum and minimum values are the average, maximum and minimum of all voyages, and do not

necessarily correspond with each other.

Additionally, drop tower tests were undertaken to determine the possible range of bulk densities

achievable after loading in the hold and to verify the values obtained by laser scanning. The test

involved dropping 20 kg of IOF sample at a given moisture content from a predetermined height into a

catching can of known volume. After levelling the material, the weight is taken to estimate bulk

density. Drop heights that simulate the materials path from the shiploader into the vessels cargo hold

(20 m) were performed at moistures in the range of cargo actual shipping moistures.

the largest compaction process is due to initial loading of the cargo (drop from 20+m at 12000tph).

Laser scanning of partial filled holds produced the same result as fully filled holds, confirming the

loading process governs the compaction. provides the results and show for the three Australia-A IOF

products, the drop tower results for bulk density are the same or slightly greater than those

determined by laser scanning. This indicates that the largest compaction process is due to initial

loading of the cargo (drop from 20+m at 12000tph). Laser scanning of partial filled holds produced the

same result as fully filled holds, confirming the loading process governs the compaction.

Table 4: Bulk densities determined by Drop Tower Tests

D1 D2 D3

Average Bulk Density

(t/m3)2.23 2.14 2.09


1.3.2 Australia-B dry density determination

Australia B conducts regular density determinations on its IOF products. The routine quarterly bulk

density determinations are based on determination of loose bulk density and firm packed density

measurements. Figure 7 shows the routine dry bulk density for Australia B products, whereby the bulk

density variation for all products is less than 0.1 t/m3.

Figure 7: Quarterly dry bulk density

As part of the cargo stability measurements, laser scanning surveys of cargo holds were undertaken

at loading and discharge ports. The Terrestrial Laser Scanning of each hold involved two instrument

setups in positions that minimised the data shadows created by the various peaks and troughs of the

product surface. The two setup locations where on alternate sides of the hold, the bow and the stern,

with one setup placed towards the port side, the other to the starboard. A high-resolution 360° scan

was performed at each setup, producing three-dimensional point spacing of 6 mm by 6 mm at 10 m.

There were two different scanners used for the project. All scans undertaken at load port were done

using a Zoller and Fröhlich Imager 5010, whereas a Leica HDS6000 was used at the discharge port.

Conformance tests to ensure that the datasets from the two different scanners were comparable were

conducted. Cloud to cloud disparities were <2 mm at 10 m, well within instrument specifications.

Altogether more than twenty one holds were scanned, of which seven were commissioning related

and only conducted at the discharge port. This density data is shown in Figure 8 and corresponds to

Quarter 13 from Figure 7.


Figure 8: Cargo density by laser scanning

There is good agreement of the bulk density data from routine measurements and the laser scanning

measurements for Quarter 13 from Figure 7 and the average for Product A and Product C in Figure 8.

The volume change for all surveyed holds is graphed in Figure 9. The measured volume change is

consistent within each product surveyed. Regardless of product, the volume change during the

journey is much less than 5%.

Figure 9: Volume change / compaction due to voyage undertaken in Q13

When the new volume is translated to a product density change for Product A the dry density increase

is about 0.08 t/m3 as per the volume change, 3%. For Product C the dry density increase is less than

0.05 t/m3 or 1%.

The moisture determination for conversion to dry bulk density is by ISO3087.


1.3.3 Brazilian dry density determination

Likewise to Australia-A testing methodology, ISO3852 is employed to determine the bulk density of

Brazilian IOF material. As is routine practice, the bulk density is assessed under industrial conditions

(i.e. onboard ships, port stockpiles, cargo spaces) and assessed under laboratory scale. Table 5

below provides data that compares real world bulk densities (i.e. under compaction) to bulk densities

used according to ISO3852 for four samples of Brazilian IOF. Further results of 147 other IOF

materials validated that the real-world dry bulk densities are approximately between 2100 kg/m³ and

2700 kg/m³.

Table 5: Densities and void ratios for Brazilian IOF

The Cone Penetration Test (CPT) method can be employed on board vessels to determine the cargo

density profile of the material loaded. These tests are performed using a cylindrical penetrometer with

a conical tip that penetrates the stow in the cargo space at a constant rate. Here, the forces of the

cone and the friction sleeve are measured. The equipment is shown in Figure 10. Results for the CPT

work will be discussed in TWG Report 4. In order to assist in the CPT findings and validate the

compaction tests inside the cargo holds, laser scanning was also employed, as seen in Figure 11:

Laser scan image inside a Brazilian IOF cargo hold of a Capesize Vessel.


Figure 10: Equipment used in CPT on top of the cargo

Figure 11: Laser scan image inside a Brazilian IOF cargo hold of a Capesize Vessel


1.4 Determination of Specific Gravity (SG) and the effect on TML.

As previously outlined in Section 1.2, SG and solids dry density are critical in determining an accurate

void ratio value. It is important that the SG is measured as accurately as possible, as small deviations

in the SG value can influence the compaction curves and saturation lines determined in the PFT.

Techniques such as the use of water displacement methods, glass pycnometers and helium

pycnometers are readily employed in the minerals industry. The determination of SG should be done

with a recognised international or national standard.

The sections below give an indication as to how the TML changes significantly with increments in the

SG value for each of the TWG members. The PFT C method has been used to determine the TML.

1.4.1 Australia –A

As outlined in Section 1.2, the void ratio can be calculated by the following equation.

Void Ratio, e=SG xWS

SG affects the void ratio and hence will alter the compaction curve and saturation lines.

According to this, if SG increases, the void ratio increases and the PFT curve shifts upwards. The

negative gradient of the curve (occurring before the OMC) when shifted upwards causes the intercept

with the saturation line to occur at a higher water content. Therefore, the TML increases.

The data represented in Table 6 below give an insight into how the TML changes for three samples of

Australia-A iron ore (D1, D2 and D3) with small changes in SG. Testing has been done in accordance

with AS1289.3.5.1.


Table 6: Australia-A changes in TML with varying SG

Sample SG (t/m3) TML (%) TML Difference

(%)

D1

4.4 X+6.3 -

4.6 X+6.5 0.2

4.8 X+6.6 0.3

5.0 X+6.75 0.45

D2

3.9 X+6.15 -

4.1 X+6.55 0.4

4.3 X+6.85 0.7

4.5 X+7.15 1.0

D3

3.9 X+5.7 -

4.1 X+6.15 0.45

4.3 X+6.5 0.8

4.5 X+6.75 1.05

1.4.2 Australia –B

For the PFT investigation the SG determination method has been according to AS 1289.3.5.1. A

series of replicate samples were tested to investigate the effect of particle size on the pycnometer

test. Figure 12 shows that if the sample is pulverised to 150 micron there is no difference to treating

the sample as received.


Figure 12: Effect of sample pulverisation on helium pycnometry

The SG determination is a critical part of the PFT. A key learning from developing the PFT method

and assessing results from external laboratories was around the SG determination. In particular, if a

TML curve is completed and the curve shows more than 100% saturation more it was due to an

inconsistent SG result. Figure 13 shows the variation of TML with SG.

Figure 13: Effect of SG on TML


1.4.3 Brazil

Brazil has employed two methods to determine the SG value of their IOF material, water displacement

in a glass cylinder and a high precision helium pycnometer. Two different samples of Brazilian IOF

were used (Sample 1 and Sample 2). The results can be seen below in Table 7 and they show that

the water displacement method underestimates the SG compared to the helium pycnometry, resulting

in a lower TML value.

Table 7: Influence of different measurements techniques of density of solids on the TML for two different Brazilian IOF samples

Brazilian IOF

Glass Water Displacement

SG (t/m3)

TML (%) Helium Pycnometer

SG (t/m3)

TML (%) SG Absolute

Difference SG (t/m3)

TML (%) Absolute

Difference

Sample 1 4.30 X+1 4.76 X+1.7 0.46 0.7

Sample 1 Duplicate

4.40 X+1.1 4.76 X+1.7 0.36 0.6

Sample 2 4.47 X+2.1 4.91 X+2.6 0.44 0.6

Sample 2 Duplicate

4.50 X+2.1 4.91 X+2.5 0.41 0.4

2 KEY FINDINGS - TWG RESEARCH ON PROCTOR-FAGERBERG TEST DEVELOPMENT.

2.1 The Optimum Moisture Compaction (OMC) point for the IOF tested occurs between 90-95% saturation.

The key findings from this test work are:

Research into the IOF material from Australia-A (Figure 14 and Figure 15), Australia-B

(Figure 16) and Brazil (Figure 17 and Figure 18) revealed that the OMC point occurs

between 90-95% saturation when compared with Fagerberg’s original work; whereby OMC

occurs between 70-75% saturation for mineral concentrates.

The various compaction curves represented in the plots below are due to changing energy

inputs by varying parameters such as hammer weight, hammer drops and drop height.

Lower energy inputs results in an upwards shift of the compaction curve as the material is

less dense and hence has a higher void ratio.


2.1.1 Australia -A

Figure 14: results for Australia-A D1 sample shows the OMC exceeding 90% saturation

Figure 15: Close-up of Figure 9 around the OMC points for Australia-A's IOF material


2.1.2 Australia –B

Figure 16: Australia B Product C PFT results


2.1.3 Brazil

Figure 17: PFT results for Brazilian IOF material shows the OMC exceeding 90% saturation

Figure 18: Close-up of Figure 17 around the OMC points for Brazilian IOF material


2.2 Variations in applied compaction energy have a first order impact on the dry density of IOF material.

As previously outlined in Section 1, Fagerberg developed five testing methods (A-E) that represented

different forms of compaction energy being applied to the sample in the Proctor mould. Each form of

compaction energy produces a different compaction curve. A study was undertaken to investigate the

following testing variables and their impact on the dry density of IOF.

Number of hammer drops per layer

o This study was performed to investigate the effects of changing the number of drops

per layer and its associated error with respect to the repeatability of dry density tests.

Additionally, it is to validate the use of 25 drops per layer, as Fagerberg had originally

outlined in his original research.

Height of hammer drop (cm)

o This study was performed to investigate the effects of changing hammer drop height

and its associated error with respect to the repeatability of dry density tests.

Additionally, it is to validate the use of the drop heights associated with the Method C

and Method D hammers, which are 20 cm and 15 cm respectively.

Weight of hammer (g)

o Proctor-Fagerberg tests using the Method C and Method D hammers were performed

on the IOF material to align with in-hold cargo measurements (eg. bulk density and

void ratio).

Three different material types (D1, D2 and D3) from Australia-A were tested in this study.

Two different material types (A and C) from Australia – B were tested.

Two material types (Sample 1 and Sample 2) of Brazilian IOF were used.

2.2.1 Varying number of hammer drops per layer directly impacts the dry density of the IOF material.

The key findings from this test work are:

Increasing the number of drops per layer to 35 evidently results in higher compaction

energies when compared with 5 drops per layer.

PF plots for Australia-A (Figure 19 and Figure 20) indicate dry density increases with

increasing the number of drops per layer.


Australia B results show that dry density increases with the number of hammer drops per

layer (Figure 21 and Figure 22).

Results from two different Brazilian IOF samples (Sample 1 and Sample 2) indicate a similar

trend such that dry bulk density increases linearly with the logarithm of compaction energy

(Figure 23).

It is evident from Figure 24 that when comparing the number of drops per layer with the dry

density of the material, there is an asymptotic relationship present. The asymptotic part of the

curve begins to develop only after about 15 drops per layer

Therefore, in the interest of minimizing variability in results, it is optional to use between 15

and 25 drops per layer for a PFT. Based on our analysis the number of drops suggest by

Fagerberg (25 drops) is adequate.

Figure 19: The effect on the PFT plot with varying number of drops/layer using the 350 g/20 cm hammer for Australia-A D1 ore (Method C)


Figure 20: The effect on the PFT plot when with varying number of drops/layer using the 150 g/15 cm hammer for Australia-A D1 ore (Method D)

Figure 21: Australia B, Product A: Number of hammer drops effect on dry density


Figure 22: Australia B, Product C: Number of hammer drops effect on dry density

Figure 23: Results of compaction tests on two different Brazilian IOF (Sample 1 and Sample 2)


Figure 24: The effect on dry density by varying the number of hammer drops per layer for Australia A’s D1 material

2.2.2 Varying the hammer drop height directly impacts the dry density of the IOF material.

The key findings from this test work are: Increasing the drop height results in higher bulk

density values when compared with smaller drop heights for Australian and Brazilian IOF

material (Figure 25, Figure 26 and Figure 27).

The 150 g and 350 g hammer showed a decreasing standard error with an increase of drop

height across all material types for Australia-A (Figure 28 and Figure 29). The maximum error

in the dry density is 0.02t/m3, which is approximately 1% which can be accounted for in

technique error (drop height, location of each drop on the sample, etc), weight and moisture

measurement errors.

It is recommended to use a drop height of 15 cm or greater with 25 drops per layer and 5

layers per PFT. This supports all of Fagerberg’s original methods (Figure 28 and Figure 29).


Figure 25: Proctor-Fagerberg compaction curves for Australia-A D1 ore using 150 g hammer at 5cm and 15cm drop height

Figure 26: Australia B: Increasing drop height increases dry density


Figure 27: Proctor-Fagerberg compaction curves are plotted for the same sample of Brazilian IOF using the 350 g hammer at different drop heights with 25 drops per layer

Figure 28: The standard error associated with varying hammer drop height using dry density values at the as received moisture content. The 150 g hammer with 25 drops per layer

has been used with D1, D2 and D3 material.


Figure 29: The standard error associated with varying hammer drop height using dry density values at the “as received” moisture content. The 350 g hammer with 25 drops per

layer has been used with D1, D2 and D3 material

2.2.3 Dry density (t/m3) vs. compaction energy (kJ/m3)

The following plot (Figure 30) represents the results from all the tests performed by Australia-A to

investigate the effect of compaction energy on the dry density of the D1, D2 and D3 material. It was

found that a logarithmic increase in compaction energy results in a linear increase in dry density.

These results validate that any form of compaction energy (e. g., varying hammer weight, drop height

or number of drops) has a direct impact on the dry density of the material and that each method was

equally as efficient in compacting the sample and increasing the dry density.


Figure 30: Dry Density (t/m3) vs. Compaction Energy (kJ/m3) for D1, D2 and D3 material

2.3 Compaction energies generated with the Method C hammer for Iron Ore Fines are excessive.

Upon analysis of the material properties and cargo observations for IOF, it was found that the dry

density and void ratio values measured do not directly match the density and void ratio values

obtained by using the Method C hammer which is currently stipulated in the code. The Method C

hammer overestimates the dry density and underestimates the void ratio for IOF.

IOF material bulk density values have been used to calculate the corresponding dry density and

resultant void ratio for a particular material. It is important that the compaction curves relates to the

void ratio values, as Fagerberg previously found. For the IOF material tested, this can be achieved by

varying the hammer weight, whilst maintaining all other variables constant.


2.3.1 The key findings from this test work are:

- Using a lighter hammer weight increases the void ratio whereby a less dense compaction is

obtained. The curve now aligns closer with the given bulk density values from actual in-hold

cargo measurements for Australia A’s IOF material (Figure 31, Figure 32 and Figure 33).

- To be comparable with the loaded cargo conditions, as intended by the IMSBC Code,

Australia-B’s IOF material required a change in the compaction energy. To ensure consistent

application of the compaction effort a simple change from the PFT C hammer (350 g, 20 cm

drop height) to the PFT D hammer (150 g, 15 cm drop height) was made. The result of this

change was a decrease in compaction. The resulting dry density (and void ratio) in the PF

test at the “as shipped” gross moisture (the moisture of the material at the time of loading),

being calibrated to the loaded dry density and void ratio measured in the ships (Figure 34 and

Figure 35).

- It was found that the dry bulk density of Brazilian IOF material can be matched by adjusting

the compaction energy by varying the number of hammer drops per layer using the Proctor C

hammer (Figure 36). Despite this, it is debateable as to whether 4 drops per layer is adequate

to comply with the IMSBC Code (Section 1.3.4.1) that states the material “is (to be) tamped

uniformly over the surface of the increment”. Additionally, 4 drops per layer only applies little

compaction (14 kJ/m3) to the material and does not allow for a sufficient safety margin with

respect to the in-hold dry bulk density specified. Therefore, plots have been provided using

the PFT D hammer in accordance with the Fagerberg’s testing methods (Figure 37 and

Figure 38).

- The PFT D hammer ( 150 g / 15 cm drop height with 25 drops per layer and 5 layers per test)

is representative of the given bulk density for all the IOF material tested in this study.

- The procedure for conducting the IOF PFT D method is outlined in Appendix A2.- The average bulk density is a practical and effective way to describe IOF cargo loading

conditions and it is required to be stated on the shipper’s cargo declaration as per section 4.2

of the IMSBC Code.

- Drop tower results align with the average of the measured cargo bulk densities, indicating that

the average bulk density of the cargo is governed by the loading process.


2.3.2 Australia – A

Figure 31: PFT plots for determination of hammer selection for D1 ore






2.3.3 Australia – B

Figure 34: Australia B, Product C: PFT C hammer (150 g, 15 cm drop height, 25 drops per layer) provides compaction comparable to loading conditions

Figure 35: Australia B, Product B: PFT C hammer (150 g, 15 cm drop height, 25 drops per layer) provides compaction comparable to loading conditions


2.3.4 Brazil

Figure 36: Bulk density compaction curve using the 350 g, 20 cm hammer (PFT C) with 4 drops per layer

0,4

0,5

0,6

0,7

0,8

0,9

1,0

1,1

1,2

X + 1 X + 2 X + 3 X + 4 X + 5 X + 6 X + 7 X + 8 X + 9 X + 10

Gross Moisture Content (%)

Void

Rati

o (e

)

100% Saturation

Brazi lian IOF 1 P/F-'D' 150 ghammer

As loaded

As shipped conditions

Figure 37: Proctor-Fagerberg plot for ‘Brazilian IOF 1’ using PFT D


0,4

0,5

0,6

0,7

0,8

0,9

1,0

1,1

1,2

X + 1 X + 2 X + 3 X + 4 X + 5 X + 6 X + 7 X + 8 X + 9 X + 10

Gross Moisture Content (%)

Void

Rati

o (e

)

100% Saturation

Brazi lian IOF 2 P/F-'D' 150 ghammer

As loaded

As shipped conditions

Figure 38: Proctor-Fagerberg plot for ‘Brazilian IOF 2’ using PFT D

2.4 Proctor-Fagerberg D precision is deemed satisfactory when a testing method is consistently applied.

As was previously discussed in the TOR1 report, the consistent application of the PFT method yields

comparable results when compared with external labs. Figure 39 indicates minimal difference

between internal and external labs when using Australia-A’s IOF material with the application of the

Proctor-Fagerberg D hammer.


Figure 39: Comparative results of PF tests between an external laboratory and the laboratory of Australian-A

For twelve replicate samples of Australia B’s Product A, a precision of less than 0.2% for the TML

result was obtained for the PFT, Figure 40.

Figure 40: PFT precision trial for Australia B Product A

It can be shown that there is sufficient safety factor associated with the TML value to account for

uncertainty/variability in both the sampling and testing procedure. The 0.2% precision for the TML

obtained is one standard deviation. The 95% confidence interval is therefore +/-0.4. This confidence

interval relates to the TML / moisture content and not necessarily the saturation.

2.5 Removal of large particles from the IOF testing samples is recommended for assuring proper levelling of the sample in relation to the brim of the Proctor-Fagerberg mould.

Given the nature of the single effort dynamic compaction tests per layer or material in the mould, it is

strongly advisable to remove any coarse particles that are present. In Brazilian IOF material, there are


occasions where there is a small percentage by weight (typically <5%) of large particles. These larger

particles are problematic for proper levelling of the top layer in the mould and impact the validity of the

test. Therefore, by eliminating these large particles, adequate levelling of the sample is obtained.

Considering that IOF are nominally finer than 10 mm, the elimination of coarse particles from the test

portion should be regarded as a protection step. In practical terms, the volume and mass readings will

be facilitated and a minimum of 95% of the particles will be effectively assessed inside the mould.

Figure 41 illustrates the negative impact caused by the presence of coarse particles.

The elimination of coarse particles prior to the execution of compaction tests is a practice found in

reputable standards. ASTM D698 Standard Test Methods for Laboratory Compaction Characteristics

of Soil Using Standard Effort (12 400 ft-lbf/ft3 (600 kN-m/m3)), for instance, establishes 9.5 mm as the

maximum particle size allowed in a 4-inch diameter mould similar to the IMSBC Code Proctor-

Fagerberg recommended mould.

Figure 41: Two pictures illustrating the negative impact on levelling the sample in relation to the brim of the mould in the presence of coarse particles.


3 CONCLUSIONS

There are numerous methods available to determine cargo in-hold densities, such as

internationally recognised laboratory tests, laser scanning, cargo observations, Cone

Penetration Tests and Drop Tower Tests.

It is important that the SG is calculated as accurately as possible as small deviations in the

SG value can influence the compaction curves and saturation lines determined in the PFT.

The determination of SG should be done with a recognised international or national standard.

For all IOF tested, the OMC point exceeds 90% saturation. According to Fagerberg’s

literature, the TML can be taken by using the OMC less a nominal safety factor. By applying

this approach to this method for IOF, the TML can be determined by using the point at which

the compaction curve crosses S=80%.

o Proctor-Fagerberg C OMC mineral concentrates 70-75% saturation with TML at 70%

saturation (~5% safety margin) currently accepted by IMO.

o Proctor-Fagerberg D OMC IOF 90-95% saturation with TML at 80% saturation (10-

15% safety margin, including sampling and experimental variability)

The Proctor-Fagerberg C hammer, as outlined in the IMSBC Code, overestimates the actual

cargo dry density (t/m3) and underestimates the void ratio for all IOF tested. According to

Fagerberg’s literature, the specific compaction curve is therefore not representative of the

material tested.

Variations to the current method outlined in the IMSBC Code (i.e. changing hammer

drops/layer, hammer drop height and hammer weight) found that variable compaction

energies that are applied to the material influence the material dry density. Whilst it is possible

to change multiple parameters, changing the hammer weight alone provides conservative

results for all IOF tested. The 150 g and 15 cm drop Proctor-Fagerberg D hammer is the most

representative of actual in-hold material cargo observations for IOF.

It is concluded therefore, that the TML for IOF is best determined by using the PFT D method

and the moisture corresponding to the point where this compaction curve intersects the 80%

saturation line.

The test procedure for the PFT D method for IOF is outlined in Appendix A2.


REFERENCES

ASTM D698 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using

Standard Effort (12 400 ft-lbf/ft3 (600 kN-m/m3)), 2007. Current edition approved April 15, 2007.

Published July 2007. American Society for Testing Materials, West Conshohocken, PA 19428-

2959, United States of America.

Circular MSC/Circ.908: Uniform method of measurement of the density of bulk cargoes.

International Maritime Organization – IMO. London, 4th of June, 1999.

Fagerberg, B. and Stavang, A., (1971). Determination Of Critical Moisture Contents In Ore

Concentrates Carried In Cargo Vessels, In Proceedings of 1st International Symposium on

Transport and Handling of Minerals, Vancouver. (Kirshenbaum, N.W. and Argall, G.O., Eds). San

Francisco: Miller Freeman Publications, 1971, 174-85.

Fagerberg, B., (1965a). Hazards Of Shipping Granular Ore Concentrates Canadian Mining

Journal, 856, July, pp 53-57.

Fagerberg, B., (1965b). Hazards Of Shipping Granular Ore Concentrates -Parts II. Canadian

Mining Journal, 856, Aug, pp 81-86.

ISO 3852 Iron ores for blast furnace and direct reduction feedstocks – Determination of bulk

density. International Organization for Standardization – ISO. Third edition 2007-09-01.


APPENDIX

Appendix – A1

Void Ratio Calculations:

Void volume=V v

Water volume=V W=%Net H2O100

Water weight=W W=%Gross H2O

100

Water density=ρWtm3

Solids volume=V s

Solidsweight=W s

Saturationdegree=S=%S100

In order to determine the void ratio (e) for saturation lines on a ‘void ratio vs

gross H 2O plot:

Void ratio=e=V vV s

Saturationdegree=V wV v

GrossWater Content=GWC=( W W

W W+W S) x100


WW+W S=100% , therforeGWC=W W W S=100−GWC

100 and as the ρW=1 ,V w=WW

Void ratio=e=V w x( SGW S x S )=Ww x( SG

W S x S )¿W w

1−Wwx SGS

In order to find the void ratio using PFT data:

Drydensity=ρdry

W w=GWC100

,W S=1−W w∧as ρW=1 ,V w=WW

Volume total=V t= W S

ρdry

V S= W S

SG V V=V t−V S

Void ratio=e=(V VV S )=V t−V SV S

=V tV S

−1=

W S

ρdryV S

−1= SGρdry

−1


Alternative Calculations

Refer to background information in Section 2.

Input data needed = Gross Water Content (GWC) and Bulk Density (t/m3)

GrossWater Content=GWC=WW

WW+W S=WW

WW+1whereW S(t)=1

WW=(GWC xW W )+GWC

1WW−(GWC xWW )=GWC

¿

WW (t)= GWC(1−GWC)

In order to find the total volume of the material, the bulk density value is needed:

Υ b( tm3 )=W S+

GWC(1−GWC )V T

=1+ GWC

(1−GWC )V T

The totalVolume ;V T (m¿¿3)=W S+

GWC(1−GWC )Υ b

¿V S (m¿¿3)=W S

SG¿

VW (m¿¿3)=W W ¿

V T (m¿¿3)=W S+

GWC(1−GWC)Υ b

=V S+V W+V A ¿

V A (m¿¿3)=W S+

GWC(1−GWC)Υ b

−V S−VW ¿

Void Ratio=e=Volume of Air (V ¿¿ A)+Volumeof Water (V ¿¿W )Volumeof Solids (V ¿¿S )¿

¿¿

Saturation=S (%)=Volumeof Water (V ¿¿W )Volume of Air (V ¿¿ A)+Volumeof Solids(V ¿¿ S)¿ ¿

¿


Dry Density ( tm3

)=Υ d=Weight of Solids(W ¿¿S )

Total Volume(V T )¿

Energy Calculations:

The energy input (kJ/m3) in this report has been calculated using the following set of equations;

Energy Input per drop(J )=Mass of thehammer ( kg ) xGravity x Height (m )

Energy input per layer ( J )=Energyinput per drop x 25drops per layer

Energy input ¿themould (J )=Energy input per layer x 5layers

Energy Input Total ( kJm3 )=Energy input ¿ themould (J ) x Volumeof mould x 10−6 (m3 ) ¿1000


Appendix – A2Iron Ore Fines (IOF) Proctor/Fagerberg D test procedure

Scope

Test method for Iron Ore Fines (IOF) materials with 10 % or more of fine particles less than 1 mm, and 50 % or more of particles less than 10 mm.

The transportable moisture limit (TML) of a cargo is taken as equal to the critical moisture content at 80% degree of saturation according to the IOF Proctor/Fagerberg method test.

IOF Proctor/Fagerberg test equipment

The Proctor apparatus (see Figure 1) consists of a cylindrical iron mould with a removable extension piece (the compaction cylinder) and a compaction tool guided by a pipe open at its lower end (the compaction hammer).

Scales and weights and suitable sample containers.

A drying oven with a controlled temperature interval from 100oC to maximum 105oC.

A container for hand mixing. Care should be taken to ensure that the mixing process does not reduce the particle size by breakage or increase the particle size by agglomeration or consistency of the test material.

A gas or water pycnometry equipment to determine the density of the solid material as per a recognised standard.

Procedure

A representative sample according to a relevant standard of the test material is partially dried at a

temperature of approximately 60oC or less to reduce the samples moisture to a suitable starting

moisture, if needed. Note: no full drying for IOF samples are to be carried out. The total quantity of the

test material should be at least three times the volume as required for the complete test sequence.

Compaction tests are executed for five to ten different moisture contents (five to ten separate tests).

The samples are adjusted in order that partially dry to almost saturated samples are obtained. The

required quantity per compaction test is about 2,000 cm3.


Figure 1 Proctor Fagerberg Apparatus

At each compaction test a suitable amount of water is added to the sample of the test material. The

sample material is gently mixed before being allowed to rest and equilibrate. Approximately one fifth

of the mixed sample is filled into the mould and levelled and then the increment is tamped uniformly

over the surface of the increment. Tamping is executed as per the Proctor – Fagerberg method D, by

dropping a 150g hammer 25 times through the guide pipe, 0.15 m each time. The performance is

repeated for all five layers. When the last layer has been tamped the extension piece is removed and

the sample is levelled off along the brim of the mould with care, ensuring to remove any large particles

that may hinder levelling of the sample, replacing them with material contained in the extension piece

and re-levelling. When the weight of the cylinder with the tamped sample has been determined, the

cylinder is emptied, the sample is dried at 105oC as per a recognised moisture determination

standard, and the weight is determined. The test then is repeated for the other samples with different

moisture contents.


Definitions and data for calculations

empty cylinder, mass in grams: A

cylinder with tamped sample, mass in grams: B

wet sample, mass in grams: C

C = B – A

dry sample, mass in grams: D

water, mass in grams (equivalent to volume in cm3): E

E = C – D

Volume of cylinder: 1000 cm3

Calculation of main characteristics

density of solid material, g/cm3 (t/m3): d

dry bulk density, g/cm3 (t/m3): γ

γ = D/1000

net water content, volume %: ev

ev = E/D x 100 x d


void ratio: e (volume of voids divided by volume of solids)

e = d/ γ – 1

degree of saturation, percentage by volume: S

S = ev/e

gross water content, percentage by mass: W1

W1 = E/C x 100

net water content, percentage by mass: W

W = E/D x 100

Presentation of the compaction tests

For each compaction test the calculated void ratio (e) value is plotted as the ordinate in a diagram

with net water content (ev) and degree of saturation (S) as the respective abscissa parameters.

The test sequence results in a specific compaction curve (see Figure 2).

The critical moisture content is indicated by the intersection of the compaction curve and the line S

= 80% degree of saturation. The transportable moisture limit (TML) is the critical moisture content.


Figure 2: Compaction Curve


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