I SOIL TEST REPORT ARS METALS, NAIDUPETenvironmentclearance.nic.in › writereaddata › Online › ... · are allowed to cool, and then be reheated in a furnace prior to rolling

ANNEXURE – I SOIL TEST REPORT

ARS METALS, NAIDUPET























ANNEXURE – II PROCESS DESCRIPTION

ARS METALS, NAIDUPET MANUFACTURING PROCESS / PROCESS DESCRIPTION

MS BILLETS

The greatest advantage of the Induction Furnace is its low capital cost compared with

other types of Melting Units. Its installation is relatively easier and its operation simpler.

Among other advantages, there is very little heat loss from the furnace as the bath is

constantly covered and there is practically no noise during its operation. The molten

metal in an Induction Furnace is Circulated automatically by electromagnetic action so

that when alloy additions are made, a homogeneous product is ensured in minimum

time. The time between tap and charge, the charging time, power delays etc, are items

of utmost importance are meeting the objective of maximum output in tones/hour at a

low operational coast. The process for manufacturing steel may be broadly divided into

the following stages:

Melting the charge mixed of steel & iron scrap.

Ladle teeming practice for casting.

Continuous casting machine.

MELTING THE CHARGE

The furnace is switched on, current starts flowing at a high rate and a comparatively low

voltage through the induction coils of the furnace, producing an induced magnetic field

inside the central space of the coils where the crucible is located. The induced magnetic

fluxes thus generated out through the packed charge in the crucible, which is placed

centrally inside the induction coil.

As the magnetic fluxes generated out through the scraps and complete the circuit, they

generate and induce eddy current in the scrap. This induced eddy current, as it flows

through the highly melting rate depends primarily on two things,

1. The density of magnetic fluxes and

2. Compactness of the charge.

The charge mixed arrangement has already been described. The magnetic fluxes can be

controlled by varying input of power to the furnace, especially the current and

frequency.

In a medium frequency furnace, the frequency range normally varies between 150-

10000 cycles/second. This heat is developed mainly in the outer rim of the metal in the

charge but is carried quickly to the center by conduction. Soon a pool of molten metal

forms in the bottom causing the charge to sink. At this point any remaining charge

mixed is added gradually. The eddy current, which is generated in the charge, has other

uses.

It imparts a molten effect on the liquid steel, which is thereby stirred and mixed and

heated more homogeneously. This stirring effect is inversely proportional to the

frequency of the furnace and so that furnace frequency is selected in accordance with

the purpose for which the furnace will be utilized.

The melting continues till all the charge is melted and the bath develops a convex

surface. However as the convex surface is not favorable to slag treatment, the power

input is then naturally decreased to flatten the convexity and to reduce the circulation

rate when refining under constantly bringing new metal into close contact with the slag.

Before the actual reduction of steel id done, the liquid steel which might contain some

trapped oxygen is first treated with some suitable deoxidizer. When no purification is

attempted, the chief metallurgical advantages of the process attributable to the stirring

action are uniformity of the product, control over the super heat temperature and the

opportunity afforded by the conditions of the melt to control de-oxidation through proper

addition.



As soon as the charge has melted and de-oxidising ions have ceased. Any objectionable

slag is skimmed off, and the necessary alloying elements are added. When these

additives have melted and diffused through the bath of the power input may be

increased to bring the temperature of metal up to the point most desirable for pouring.

The current is then turned off and the furnace is tilted for pouring into a ladle. As soon

as pouring has ceased, any slag adhering to the wall of the crucible is crapped out and

the furnace is readied for charging again.

As the furnace is equipped with a higher cover over the crucible very little oxidation

occurs during melting. Such a cover also serves to prevent cooling by radiation from the

surface heat loss and protecting the metal is unnecessary, though slags are used in

special cases. Another advantage of the induction furnace is that there is hardly any

melting loss compared with the arc furnace.

LADDLE TEEMING PRACTISE

The temperature of liquid metal is allowed to rise in the furnace till the correct pouring

temperature is achieved which is checked with the help of Immersion Pyrometer. The

hot metal is poured with the hydraulic system in the preheated ladle after adding certain

fluxes so that the temperature is maintained at about 1600 degree centigrade. Ladle is

then carried by EOT charge to the concast machine and (crucible is made free for further

charge of next batch) kept above the tundish of the concast machine. The bottom of the

ladle is opened by hydraulic system and hot metal starts pouring out into the concast

machine.

CONTINUOUS CASTING MACHINE

The molten steel from the IF or the ladle metallurgical facility is cast in a continuous

casting machine (6/11 2 stand Billet Caster) to produce cast shapes including billets. In

some processes, the cast shape is torch cut to length and transported hot to the hot

rolling mill for further processing. Other steel mills have reheat furnaces. Steel billets

are allowed to cool, and then be reheated in a furnace prior to rolling the billets into bars

or other shapes.

Castings operations consist of following:-

Preparation

Match Plates (Patterns)

Preparation of Moulds

Pouring of molten steel into prepared moulds

Knocking of moulds

Finishing of casting billets

1. The process is continuous because liquid steel is continuously poured into a

„bottomless‟ mould at the same rate as a continuous steel casting is extracted.

2. Before casting beings a dummy bar is used to close the bottom of the mould.

3. A ladle of molten steel is lifted above the casting machine and a hole in t he

bottom of the ladle is opened, allowing the liquid steel to pour into the mould to

form the required shape.

4. As the steel‟s outer surface solidifies in the mould, the dummy bar is slowly

withdrawn through the machine, pulling the steel with it.

5. Water sprays along the machine to cool / solidify the steel.


ARS METALS, NAIDUPET 6. At the end of the machine, the billets are cut to the required length of 6 mtrs or

12 mtrs by gas torches.

7. Sized billets are lifted by crane to finishing yard for inspection and storage /

dispatch.



Raw Material Yard

DRI MS Scrap Iron Scrap Ferro Alloy

Scrap

Induction

Surface

Cool Water

Inlet

Hot Water

Outlet

Ladle

CCM

Billet Mould

Billet to Yard


ARS METALS, NAIDUPET THERMOMECHANICAL PROCESSING (TMT)

Thermomechanical Processing, also known as thermo-mechanical treatment (TMT), is a

metallurgical process that integrates work hardening and heat-treatment into a single

process. A description of its application in rebar steel follows.

Mild steel billets of sizes 100/110/125 mm² having the appropriate chemical constituent

i.e. Carbon, Manganese, Sulphur and Phosphorus are hated to the temperature of appx.

1150°C – 12200°C in the reheating furnace. The heated raw material is passed through

a series of electronically controlled Rolling Mills stands to produce the finished steel at a

temperature of around 950°C – 1000°C.

TMT bars are produced using the latest quenching process in automatic rolling mill

where TMT bars are hot rolled from tested raw material of required chemical

specification in a series of electronically controlled finishing stands and online PLC

controlled thermo mechanical treatment they are progressively rolled to reduce the

billets to the final size and shape of reinforcing bar. After the last rolling stand, the billet

moves through a quench box. The quenching converts the billet‟s surface layer to

martensite, and causes it to shrink. The shrinkage pressurizes the core, helping to form

the correct crystal structures. The core remains hot, and austenitic. A microprocessor

controls the water flow to the quench box, to manage the temperature difference

through the cross-section of the bars. The correct temperature difference assures that

all processes occur, and bars have the necessary mechanical properties.

The bar leaves the quench box with a temperature gradient through its cross section. As

the bar cools, heat flows from the bar‟s centre to its surface so that the bar‟s heat and

pressure correctly tempers and intermediate ring of martensite and bainite.

Finally, the slow cooling after quenching automatically tempers the austenitic core to

ferrite and pearlite on the cooling bed.

These bars therefore exhibit a variation in microstructure in their cross section, having

strong, tough, tempered martensite in the surface layer of the bar, an intermediate

layer of martensite and bainite, and a refined, tough and ductile ferrite and pearlite

core.

When the cut ends of TMT bars are etched in Nital (a mixture of nitric acid and

methanol), three distinct rings appear;

1. A tempered outer ring of martensite,

2. A semi-tempered middle ring of martensite and bainite, and

3. A mild circular core of bainite, ferrite and pearlite.

This is the desired micro structure for quality construction rebar.

In contrast, lower grades of rebar are twisted when cold, work hardening them to

increase their strength. However, after thermo mechanical treatment (TMT), bars do not

need more work hardening. As there is no twisting during TMT, no torsional stress

occurs, and so torsional stress cannot form surface defects in TMT Bars. Therefore TMT

bars resist corrosion better than cold, twisted and deformed (CTD).


ARS METALS, NAIDUPET SPONGE IRON

The reduction process is carried out in a rotary kiln (which is inclined and rotates at a

pre-determined range of speeds) at a stipulated temperature (850°C – 1050°C). The

inclination & the rotary motion of the kiln ensure that the raw materials move from feed-

end to the discharge-end of the kiln and it is during this movement that the actual

reduction of iron ore to iron takes place. The material discharged from the kiln is taken

to a rotary cooler for cooling and the cooled product, after being discharged from the

cooler moves on to the next step in the production process viz., product separation and

handling system.

For direct reduction f ore in the inclined rotary kiln, ore and coal normally pass through

an inclined kiln in a counter current direction to the flue gases in the freeboard. The flat

section, running nearly half the length of Kiln is called preheating zone, where Iron Ore,

Coal and Dolomite are heated up to reaction temperature. In this zone, moisture of the

material is driven off. After material heating, ore reduction and carbon gasification takes

place in close association with each other in the second half of the kiln, which is called

reduction zone. The volatile constituents of the coal and carbon monoxide from the bed

material are burnt, over the entire length of the kiln under controlled air supply, thereby

providing necessary heat required for the metallization process. The basic reactions for

the process are as follows:

Step I 3Fe2O3 + CO = 3Fe2O3 + CO2

Step II Fe3O4 + CO = 2FeO + CO2

Step III FeO + CO = Fe +

CO2

The rotary kiln discharge is cooled in a rotary cooler connected to the kiln, screened and

subjected to magnetic separation in order to remove the non magnetic material from the

sponge iron.


ARS METALS, NAIDUPET Schematic line diagram / outlay indicating various sections including the positions of Kiln

& WHRB boilers is as under.


ARS METALS, NAIDUPET The overall process requires duration of approximately eight to ten hours inside the kiln,

during which iron ore is optimally reduced and discharged to a rotary cooler for cooling

below 120°C, before coming out into the finished product circuit, flowchart of the

process is given below:

Raw Material Feeding at Ground Hopper

Coal

Crushing

Screening

Coal Bin

Sized Iron Ore

Crushing

Screening

Iron Ore Bin

Over Size Over Size

Lime Stone Bin

Setting up of proportion of mixed Raw Materials for Kiln Feed

Processed in rotary kiln at 1050°C with air control

Indirect Cooling in rotary cooler with Water Spray

Screening of mixed product (Sponge Iron and un-burnt Coal)

Sponge Iron Lumps + Char Sponge Iron Fines + Dolo

Drum Type Magnetic Drum Type Magnetic

S.I. Lumps Bin Char Bin S.I. Fines Bin Dolo Char Bin


ARS METALS, NAIDUPET POWER GENERATION

Power Capacity of 2 x 4 MW – WHRB Based and 1 x 4 MW FBC Based installation.

The proposed plant shall be configured with 3 Nos. of Waste Heat Recovery Boilers

(WHRB) of capacity 2 x 4 MW each oiler operating at 67kg/cm² and 485±5°C.

The balance steam for generating the rated power of 1 x 4 MW will be generated by

Fluidized Bed Combustion Boiler (FBC) using Coal and Char operating at 67 kg/cm² and

485±5°C.

The proposed on 2 x 4 MW Steam Turbine shall have one uncontrolled extraction

connected to one constant pressure detector normally working at 125°C feed

water temperature.

The Steam Generated in the boilers would be sufficient to generate 2 x 4 MW of

power.

The feed water system of Boilers is sized to support the installed capacity of

boilers to enable 8 MW power generation.

One induced draft RCC counter flow cooling tower with three cells of adequate

capacity to meet the design operating point of the proposed CPP is envisaged.

1 x 10 m³/hr rated flow capacity single stream fully manual operated outdoor

type DM Plant is envisaged for the proposed CPP.

All electrical equipment will conform to relevant IS/IEC standards and

recommendations of IEEE Standards.

One centralized Control System is envisaged for the operation of major

equipment (Boiler, STG, CW System) in the plant and other auxiliary systems

(Compressors and DM Plant) shall be operated from their relay based local

control panels/stations.

The steam at required parameter to STG would be provided through a main

steam header. All Boilers will be connected to this main steam header. The

variation in the steam generation of WHRB will vary in line with the variation in

the hot gas parameters and its flow. As discussed above, the total steam

requirement for 12 MW power generation, as per the suppliers of turbine and

generator, shall be operating at 67 kg/cm² and 485±5°C.

Therefore, the heat energy available from 350 TPD DRI kilns feeding to 3 x 4 MW

capacity WHRB Boilers & one FBC Boiler will be sufficient for generating sufficient

steam to run 3 x 4 MW turbine and generator.

Most of the power generated is to be consumed by the melt shop & rolling

sections of the unit and to ensure continuous power supply to these sections,

even if DRI Plant is completely shut down, FBC boiler will generate adequate

power to feed rolling mill.

The rotary kilns in the DRI section will be subjected to regular annual

maintenance at different intervals.


ARS METALS, NAIDUPET POWER GENERATION PROCESS

The Process-material flow chart: Captive Co-generation Power Plant

Hot Flue Gases from DRI Hot Flue Gases from DRI

WHRB & FBC Boiler / Steam Generation

Movement of Turbine & Generation of

Electricity

Power Transformers / Panels / Supply

Sponge Iron

Unit

Rolling Mill

Unit

Furnace Unit


ARS METALS, NAIDUPET FERRO ALLOYS

Product Description

Ferro-alloy is the most efficient and economic way of introducing alloying elements into

iron and steel melts in order to produce the required grades; the ferro-alloys list

therefore covers a wide range of elements which are needed for modern iron and steel

metallurgical processes and is commonly accepted that ferro-alloys are divided into two

main categories;

Bulk alloys, which are widely used in large quantities (silicon and its alloys, manganese

alloys, chromium alloys, nickel alloys) and so-called special alloys, used in relatively

limited quantities.

Various products are usually associated with ferro-alloys, either because they are

produced by the same or comparable processes, or because they are used by the same

customers (magnesium, calcium and its alloys).

Silicon is a metalloid used mainly in the manufacture of silanes, silicones and silica, as a

“hardener” or alloying element to produce aluminium alloys, and in the manufacture of

micro-processors and solar cells. Silicon is also used as a secondary smelting additive in

the manufacture of photonic devices and in the manufacture of industrial refractories.

Silica fume, a mineral composed of ultrafine spheres of amorphous silicon dioxide (SiO2),

is a product used mainly as an additive to concrete and refractories. Other applications

include an Oil Field Services additive, an additive in polymer materials, an anti-caking

agent in artificial fertilizers, and a raw material for manufacturing inorganic pigments.

Manufacturing Process

Ferro-alloys are usually produced by the reduction of a metallic ore (generally oxide) by

carbon with the addition of electric energy in a “Submerged Arc Furnace” (smelting

process) or by metals (metallo-thermic reduction), usually aluminium or silicon.

Silicon is commonly produced by a “Submerged Arc Furnace”. Polycrystalline silicon

(PCS), a hyper form of Silicon (99.99), is produced for semi-conductors and solar cells

by a chlorination process in a special reactor metallurgical-grade silicon followed by a

reaction in the presence of hydrogen at high temperatures.

A very pure Silicon metal is also produced by a patented hydrometallurgical process.

This process removes the impurities in high silicon by treatment in an iron chloride

solution, followed by a further purification process.

Silica Fume is produced during the manufacture of silicon or ferrosilicon. This electro-

metallurgical process involves the reduction of quartz. Silica fume is formed when SiO

gas is oxidized to SiO2 depending on the alloying element, the grade and other

economic/technological considerations, the details of the production processes can vary

widely.

In all cases, the production of Ferro-alloys and Silicon is an energy – intensive activity,

and Members are committed to constantly improving their operations in order to save

energy and to reduce greenhouse gas emissions helping to provide users with the

necessary supply of ferro-alloys and Silicon with minimal impact on natural resources.

The Ferro-alloys and Silicon industry has developed and improved its technology and

production processes, not only by improving the quality of the materials delivered to its

customers, but also by improving working conditions and by implementing the best


ARS METALS, NAIDUPET available technologies to reduce environmental impact. This industry provides its

employees and consumers with the highest social, safety, environmental and

occupational health standards.

Flow chart


ARS METALS, NAIDUPET Silicon based ferro alloys are produced by adding quartz., iron ore and carbon materials

to an electric arc furnace. The difference of the mixture between these reactants

depends on the silicon content in the ferro alloyed product. A typical diameter for a Si

furnace is 10 m. Three electrodes submerged into the charge supply a three phase

current that passes through the charge of the furnace and the productions demands 11-

13 MWh/ton produced silicon metal. The furnace consists of a hood at the upper part of

the furnace that directs the hot gases to a chimney that transport these to a gas

cleaning system.

The material quartz/quartzite, iron ore, coke/coal and wood chips are transported on

conveyor belts and stored separately in bins where they are charged and mixed through

charging tubes. These tubes are located with outlets towards the electrodes. The

charged material is at the same level as the floor outside the furnace surrounded by a

hood that has stoking gates at different sections and these sections can be opened

during a stoking period. The stoking charging cycle is a operational cycle. The stoking is

carried out by a special truck equipped with a stoking rod that is mounted in front of the

truck. The unevenly charged burden can be distributed with the truck through the

stoking gates. Old charged material at the surface is distributed towards the electrodes

where depressions have formed around the electrodes. These depressions are formed by

the hot reactions zone in the cavity.

The product of liquid alloy is tapped from a tap hole in the furnace lining. The tap hole

can be opened either mechanically or chemically. The metal is tapped from the furnace

into a steel ladle which interior is protected with a high temperature resistant refractory

material and subsequently cast into special steel moulds. The final product is

manufactured to customers requirements by crushing and sieving. The melt can also be

granulated.

Manganese ferroalloys are auxiliary materials added primarily to steels to give them

strength and toughness. Their compounds commonly range from 0.2% by weight. The

primary applications of manganese ferroalloys are as a manganese additive in

steelmaking, deoxidizers and desulfurizers in steelmaking, and flux for welding rods.

ANNEXURE - III

STACK EMISSION CHARACTERISTICS

Stack No 1 2 3 4 5 6 7

Material of Construction M.S M.S M.S M.S M.S M.S M.S

Stack attached to Induction

Furnace

2 x 25T

Sponge

Iron Kiln

Re-

Heating

Furnace

Re-

Heating

Furnace

Ferro

Alloys

(9MVA)

Ferro

Alloys

(9MVA)

D.G. Set

65 KVA

Stack height Above the

ground level, in m

40.0 40.0 30.0 30.0 30.0 30.0 5.0

Stack top Round or

Circular

Circular Circular Circular Circular Circular Circular Circular

Inside dimensions of the

stack at top, mm

600 600 350 350 1100 1100 200

Gas quantity – m3/hr 1080 1080 1080 1080 7744225588 74258 1000

Flue gas temperature, oC 70 70 70 70 110011 101 100

Exit velocity of the gas, m/s 10 10 10 10 2222 22 15.43

Emission concentration,

mg/m3

SO2 --- --- 462 462 150.29 150.29 462

NOx --- --- 210 210 60.60 60.60 210

SPM 50 50 11 11 48.48 48.48 11

Emission rate, g/s

SO2 --- --- 0.1386 0.1386 3.1 3.1 0.1386

NOx --- --- 0.063 0.063 11..2255 1.25 0.063

SPM 0.045 0.045 0.0033 0.0033 11..00 1.0 0.0033

ANNEXURE - IV

WATER BALANCE DIAGRAM

All values are in KLD

From State Water Board

/ Borewell

304

Induction Coil

Cooling (2 x 25T)

Concast Cooling

TMT Cooling

(Rolling Mill)

Domestic

Consumption

40

18

20

14

14

18

16

11.2 STP

186

Cooling Pond I

Cooling Pond II

Guard Pond

Green Belt

Sponge Iron Kiln 200 130

WHRB 12 8

RO Plant

186

Mechanical

Evaporator

70

38

34

200

78

Dust Suppression

4

104

ANNEXURE - V

WASTE MANAGEMENT/TREATMENT & DISPOSAL

LIQUID WASTE MANAGEMENT

Description of effluent generated Qty (KLD)

Industrial (Cooling water blow down) 186.0

Sewage 11.2

Total 197.2

The cooling water blowdown will be taken to 2-consecutive Cooling Ponds, and then to

Guard Pond. From Guard Pond the water will be used for green belt. R.O. Plant is

proposed. The Treated Water will be reused for process. About 200 KLD of Fresh Water

will be required.

The domestic sewage will be treated in Sewage Treatment Plant and discharged for

green belt.

SOLID WASTE MANAGEMENT

The solid waste generated will be slag from melting and dolochar from sponge iron

plant.

The quantity of solid waste that would be generated is as follows

Solid Waste Quantity (TPA) Mode of Disposal

Char Coal/ Dolo Char 4680 Used in AFBC Boiler

Slag 10860 Ground slag will be Sold to

Cement manufacturers

Returnable Scrap 4080 Recycled in process

Mill Scale 5520

Ash 43 TPD Sold to cement industries

Documents

I SOIL TEST REPORT ARS METALS, NAIDUPETenvironmentclearance.nic.in › writereaddata › Online › ... · are allowed to cool, and then be reheated in a furnace prior to rolling