hzl chanderiya pyro training report

Kunal Gupta M.B.M. Engineering College, Jodhpur

CHAPTER 1 INTRODUCTION

LOCATION OF HZL PLANTS IN INDIA

M.B.M. Engineering College, Jodhpur 1


VISIONBe a world-class zinc company, creating value, leveraging mineral resources and related core competencies.

MISSION Be a lowest cost zinc producer on a global scale, maintaining market leadership. One million tonne zinc-lead metal capacity by 2010. Be innovative, customer oriented and eco-friendly, maximizing stake-holder value. Refined zinc production capacity 669,000 tonnes per annum. Refined lead production capacity 85,000 tonnes per annum.

Continuous operational improvements, meticulous planning, constant innovation, extensive R&D, technological upgradation and so much more- HZL has come a long way and grown into a multi-unit and multi-product company.

HISTORY

Hindustan Zinc Limited was incorporated from the erstwhile Metal Corporation of India on 10th January 1966 as a Public Sector Undertaking. In April 2002, Sterlite Industries (India) Limited made an open offer for acquisition of shares of the company consequent to the disinvestment of Government of India’s stake (26%) including management control to Sterlite and pursuant to the regulations of SEBI Regulations 1997 acquired additional 20% of shares from public. In August 2003, Sterlite Industries acquired additional shares to the extent of 18.92% of the paid up capital from Government of India (GOI).HZL produces Zinc, Lead and some by-products including Sulphuric Acid, Silver and Cadmium. HZL achieved an all-time high with a record output of 2,61,226 tonnes Zinc and 6,14,938 tonnes production of Zinc concentrate during 2003-04.Today HZL is India’s leading base metal producer.

HZL is a vertically integrated Mining & Smelting company, gearing up to: Harnessing mining resources to help India achieve self-sufficiency in Zinc. Become a global leader in Zinc production. Create value for all entities whether it is Customers, Investors or Employees



HINDUSTAN ZINC (CHANDERIYA PLANT)

HZL operates smelters based on pyrometallurgical (Chanderiya Lead Zinc Smelter) and hydrometallurgical (Debari and Vizag Zinc Smelters) process routes. The Chanderiya Lead Zinc Smelter is one of the most cost-efficient pyrometallurgical Zinc Smelters in the world

Commissioned: 1991

Location: 120km east of Udaipur, Rajasthan

Capacity: 669,000 tpa of refined Zinc85,000 tpa of refined Lead

Details: A pyrometallurgical smelter using ISPtechnology. Main by-products areSulphuric Acid and Silver and one ofthe by-product is Cadmium.

Certification: ISO 9001:2000, ISO 14001:1996, OHSAS18001:1999

PRODUCTION CAPACITIES

PRODUCTS CAPACITY (TPA)

REFINED ZINC 70000REFINED LEAD 35000SULFURIC ACID 176000SILVER 74COPPER CATHODE / SULPHATE 2100CADMIUM 375



CHAPTER 2 SAFETY DEPARTMENT

Safety is one of the fundamental needs of all living beings. Accident is an unwanted event held due to carelessness. So precautions must be taken to avoid accidents.There are two main reasons of accidents:

Unwanted Acts Unwanted Conditions

In accidents occurred by unwanted acts, the worker is directly responsible. These occur due to carelessness, lack of concentration and over confidence of the worker. It can be minimized by maintaining concentration and being patient while working.

The main reasons for accidents in form of unwanted acts are: Use of machine or equipment without permission. Loading material improperly. Oiling or greasing machines in running condition. Standing in unsafe manner or condition. Use of unsafe tool and lack of safety equipment. Disobey the instructions and rules.

Some unsafe conditions which motivate accidents are: Work on gradeless machine. Presence of grease on floor. Bad housekeeping and unsafe clothing. Breaking or absence of railing on platform.

There are many rules for safety but main golden rules are: Follow all instructions and rules. Correct or report unsafe conditions immediately. Wear safety equipments whenever required. Keep the workplace clean and tidy.



CHAPTER 3 ABBREVATIONS USED

ABBREVATION: FULL NAME:ISF Imperial smelting furanceSHG Special high grade ZincESP Electrostatics prcipitateLSHS Low sulphar high stuckWGC Wet gas cleaningLC Lead columnCC Cadium columnZRP Zinc refinery plantLRP Lead refinery plant



CHAPTER 4 LIST OF FLOW CHARTS

FIG NO: FIG NAME:F.7.1 SMELTING PROCESS FLOW CHARTF.7.2 PYRO PLANT PROCESS FLOW CHARTF.8.1 SINTER PLANT FLOW CHARTF.9.1 PROCESS FLOW CHART OF SULPHURIC ACID PLANTF.10.1 PROCESS FLOW CHART OF ISF PLANTF.11.1 PROESS FLOW CHART OF ZINC REFINERY PLANTF.12.1 PROCESS FLOW CHART OF LEAD\SILVER REFINARY



CHAPTER 5 LIST OF TABLES

TABLE: TABLE NAME:T.1.1 PRODUCTION CAPACITIEST.9.1 PARAMETERS OF ACID PLANTST.11.1 PROPERTIES USED IN REFINERY



CHAPTERS 6 LIST OF DIAGRAMS

DIAG.NO: DIAG.NAME:D.1.1 VARIOUS OPERATING PLANTD.8.1 SINTER PLANT D.9.1 SULPHURIC ACID PLANT



SOURCES OF RAW MATERIALS

(A) Mines in Operation :1.Zawar Group of Mines:Zawar group of mines (Mochia, Balaria, Zawar Mala,& Baroi) is situated in the Girwa Tehsil of Udaipur District of Rajasthan at a distance of about 35kms from Udaipur , amidst a valley of Arawali hills.

2.Rajpura-Dariba Mines:The multi-metal Rajpura-Dariba Mines, which is located about 85km away from Udaipur (Raj.) has demonstrated ore reserve of about 16.4 million tones having metal content of about 6.9% zinc& 2.2% lead.

3. Maton Rock Phosphate Mine(Udaipur) :Maton mine has been developed to meet rock-phosphate requirements for the super-phosphate &phosphoric acid plant at Debari.

4.Rampura Agucha Mining Complex:The prestigious Rampura Agucha Open Cast Mining Complex is Asia’s richest &largest lead –zinc deposit.. It is situated in Tehsil Hurda, District Bhilwara in Raj.The discovery of a world class diposie of 60.6 million tones at Rampura Agucha, containing 15.4 % metal has dramatically altered the prospect of not only reducing the cost of production of zinc and lead, but also the expansion of HZL’s production capacity resilting in increasing the demand satisfaction up to 82 %for zinc and 61%for lead.

5. Sargipali Mine (Orissa)

6. Agnigundala Lead Mine (Guntur, A.P.)

(B) Smelters in Operation :1. Debari Zinc Smelter, Distt. Udaipur (Raj.)2. Vizag Zinc-Lead Smelter(A.P.)3. Tundoo Lead Smelter (Dhanbad), Bihar4. Chanderiya Lead-Zinc Smelter



CHAPTER 7 PYRO PLANT

.PROCESS OF HZL

M.B.M. Engineering College, Jodhpur

Zn REFINING

SINTERING

SMELTING

PYRO METALLURGY HYDRO METALLURGY

IMPERIL SMELTING

REFINING

LEACHING

ROASTING

PURIFICATION

ELECTROLYSIS

MELTING &CASTING

Pb REFINING

DCDA-H2SO4

AUSMELT

PW &SHG Zn&Cd Metal as By Product

Pb&Ag,CuSO4 as By Product

HG&SHG

10


PROCESS FLOW DIAGRAM PYRO PLANT



CHAPTER 8 SINTER PLANT

EXTERIOR VIEW OF SINTER PLANT



PROCESS FLOW CHART OF SINTER PLANT


RMH Bins Common Belt Conveyer

Mixing Drum

Conditioning Drum

Sinter Machine

Sinter Breaker

Spike Roll Crusher

ClassifierCorrugated Roll Crusher

Smooth Roll Crusher

Cooling Drum

To ISF

Return Fines Bins

13


HZL’s CLZS zinc and lead production begins with zinc and lead concentrates wherein zinc and lead are present as sulphides is imported from its own captive mines in India. Concentrates is received in trucks and stored in a Raw Material House. From the Raw Material House, it is transported to Bins in Sinter Plant by a well controlled belt conveyor system, where along with certain other necessary ingredients like fluxes, secondary materials and water it is mixed in a prefixed proportion and fed to sintering machine. Sintering serves the dual purpose of converting the sulphides into oxides and agglomerates the product into porous, high strength lumps called sinter.In the sintering process the sulphides of lead and zinc react with oxygen of air to form SO2 gas:

The sinter plant has following main sections:1. Raw Material Handling Plant (RMH)2. Charge Proportioning and Conditioning System3. Sinter Machine4. Sinter and Return Fines Handling (Crusher Plant)5. Gas Cleaning (Acid Plant)6. Slurry Handling

1. RMH (Raw Material Handling):

The raw material from mines is first dumped in a yard then it comes in RMH Plant through Belt Conveyor. The unloading system of belt conveyors takes the material to the respective bay through a tripper conveyor. *The tripper conveyor is like a belt, which is mounted on the head pulley and is driven by a gear coupling (spiral helical gear, the gear box is SCN 180 where S→Spur gear, C→Triple state, 180→code for size and other specifications). With the tripper conveyor Take-up Pulley Arrangement (automatically adjustable system) is there, which prevents breaking of belt due to stretching while working. This arrangement is perpendicular to the tripper conveyor and head pulley arrangement. **From the belt conveyor raw material is transferred to the respective bay via Shuttle Conveyor. Water spraying is done with the help of Fly-Over, so that the powder form of material doesn’t scatter here and there. *

From the bay the material is fed into the hoppers using Pay Loaders. Hopper transfers the material on the belt conveyor, which carries the material to the Sinter building. *Impact idlers are used in driving this belt conveyor to absorb sudden shocks. Some magnetic separators are put in between the way to separate the magnetic impurities present in the raw materials. The basic raw material used in the industry is as follows:

1. Zn Concentrate 2. Pb concentrate3. Lime Stone



4. Ferous Oxide 5. Calcium Oxide6. Silicon Oxide7. Sulphur

2. Charge Proportioning and Conditioning System:

The raw materials can be made to pass through a disintegrator and then through hammer mill to break the oversized particles. Now the material comes on the shuttle conveyor via a belt conveyor. Raw material is transferred to the respective bin via Shuttle Conveyor.Here we have kept 13 storage bins.

6 for Zinc concentrate (cap.→50 cu.m.)4 for Lead concentrate (cap.→50 cu.m.)1 for bulk concentrate (cap.→50 cu.m.)1 for iron flux (cap.→50 cu.m.)2 for limestone (cap.→50 cu.m.)1 for spare dross (cap.→25 cu.m.)2 for return fines (cap.→25 cu.m.)

All bins are equipped with Vibrators and Shock Cannons to prevent blockage, provide uniform charging and separate out the undersized particles.

The feed basically contains:1. Return fine2. Ventilation dust3. Rich gas dust4. Bag house dust5. Blue powder6. Leach residue from Copper dross leaching7. Leach residue from Cadmium plant8. Sludge from lead refinery

The raw material from the bins comes on a belt conveyor that moves on the rollers. This system is called Weigh Feeder because a rod is attached among the rollers to sense the material load in tones per hour. The speed of all weigh feeder bins is 6 times lesser than the speed of the feeder of return fines bin due to the 6 times more requirement of return fines in sinter machine. Generally the ratio between the crude charge and return fines is in the range of 1:3 to 1:5. In order to have a sulphur of 6% in the feed to sinter machine.From weigh conveyors the charge comes on the collecting belt, common to all bins. From this belt the charge is fed to mixing drums. The mixing drum is a cylinder in which the charge is mixed with the moisture, 2 to 4% water is added for that.



The sketch of the mixing drum and its drive is somewhat like this-

Bearings

MIXING DRUM

In its mechanism the motor drives the smaller drums, which drive the mixing drum. The spherical roller bearings are provided so that no rubbing occurs. The charging and discharging is through a V-belt arrangement. In the mixing drum some intermediate cones are provided so that slipping of charge does not occur. When the charge gets stuck in between the cones then the charge find time to mix with the moisture.From mixing drum the charge goes to the conditioning drum, where further water is added. The difference between the mixing and the conditioning drum is that the no. of cones in the latter one is more. The conditioning drum maintains the amount of moisture (approx. 6%) in the charge in the sinter machine feed. In this drum lumps of charge are formed and thus size of fines is increased. The mechanism of this same as that of the mixing drum.

3. Sinter machine:

The updraft sinter machine has an area of 120 m2 and 109 pallets each measuring 3m*1m in size. There are 444 grate bars in a pallet.To drive the sinter machine, is used a motor and a gear box system. The drive gear is flexible and it is hanged at one side of machine. It is made flexible and movable because the machine is very long, so there are jerks in some conditions. So to withstand it drive gear box is made flexible and thus the drive does not get damaged.

The specifications of drive gearbox are-Supplier – M/S-CITROEN MESSIAN DURAND FRANCEType – 71 HAA-165-500F-H3C20Input Ratio –128/18*76/3*40.078 = 7219.90Input Speed – n1 – 1500rpmOutput Sped – n2 – 0.207-27rpmMotor (kW) – 75


Small drum

Small drum

Mixing drum

Motor

dischargeinput

16


Above the sinter machine the main and ignition layer bins are located. Through ignition bin charge is passed on the pallets to form the ignition layer, the thickness of which is generally adjusted to give 30mm height. The ignition layer is fired by 2 burners operating on LSHS (low sulphur heavy stack) to get about 1000C hood temperature.The ignition gases are drawn by the ignition waste gas fan through the wind box and conveyed to recirculating gas fan. Dust and spillage are removed in a solid separator. The ignition wind box, is equipped with two screw conveyors which are to seal and discharge the sinter machine dust collecting through.

Heat 1000C

30mm layer

Heat drawn from bottom

IGNITION LAYER IN BINS

On the 1000C burnt ignition layer, is formed the main layer 360mm in all (30mm ignition layer+330mm fresh charge). The 330mm layer comes from main layer hopper which is located above the sinter machine. The burnt 30mm layer of charge with air now heats the 330mm layer of fresh charge.

330mm360mm

30mm

Air+ O2

LAYER FORMATION IN BINSTo supply O2, there are 3 fresh air fans and one recirculating fan supplying fresh air and recirculates to 17 wind boxes of the sinter machine. The gases above the both updraft windboxes are low in SO2, extremely humid and at low temperature. These gases are mixed with the hot gases from the


Ignition layer

Main layer

Ignition layer

17


discharge and of the sinter machine and recirculated to the last 3 windboxes at the discharge end of the sinter machine. There are 5 Cyclones for dust removal og ventilation air and recirculating gases in order to avoid any dust build up in the ducts and also to avoid wear of the fans.The SO2 gas is sucked from the top and the duct is situated in the mid of the sinter machine.The reaction is as follows-

The maximum of SO2 is sucked at mid and the remaining from the back of sinter machine with hot gases. The SO2 from mid is sent to Wet Gas Cleaning Plant (WGC) through a HGP with the help of booster blower.

The specifications of the plant are as follows:Effective updraft are a of the sinter m/c 120 m2,

Width of the pallet 3.0 mCapacity (Dry basis) Sinter material 4600tons per daySpecific Sulphur burning rate 1.6 tons per square meter per daySinter Production 1080 tons per daySulphur content of mixture <1%SO2 content of the gases >5%Moisture Content <7%Bulk density of the crude charge 2.5 tons per cubic meter (Avg.)

The ignition chamber contains the horizontally arranged oil burners. Oxidation reaction produce such heat that local melting at contact surface takes place between single grains as a result of that they agglomerate into lumps. The temperature at the outlet of the sinter machine is around 800◦ C.

4. Sinter and Return Fines Handling (Crusher Plant):

Because the sinter from sinter machine is in the form of very big size lumps, which cannot be directly fed to furnace, and it needs to be broken in the size of approximately 65 to 130mm. This sizing is done in the Crusher Plant. Also, as the major part of the input to sinter plant is the return fines and for that the fines are prepared in the Crusher Plant.Now the agglomerated material is directly fed to the claw crusher or Sinter Breaker that is placed just after the sinter machine. This crusher helps in reducing the size of sinter upto 300mm. And the temperature at this stage is approximately 500C.Now the sinter is sent to the Spike Roll Crusher that gives the size of sinter as 130mm. Before this crusher a Vibro-Feeder is provided to give uniform charging to crusher.Finally the material goes in the Rose Roll Classifier. The sinter of size less than 65mm and greater than 65mm is classified in this classifier. The sinter of size 65 to 130mm comes to Production Bin, which is the input for ISF Plant.The –65mm sinter (i.e. the size is less than 65mm) passes through another circuit so that proper size of fines can be fed to the sinter input in the form of return fines. The size should be approximately 6mm for proper permeability is achieved.



The size of returns is reduced upto 25mm in the Corrugated Roll Crusher. Further the size is reduced in the Smooth Roll Crusher to 6 to 13mm, which is the required size of return fines. At this stage the temperature is approximately 300C that is further reduced to 90C in the Cooling Tower or Cooling Drum. Thus formed fines are the feed for the sinter plant.The material, which is agglomerated in the sinter machine, is mainly rich in ZnO and PbO, which are now; send to the ISF plant to feed it to the furnace. The reaction-taking place in the plant is as follows:

These are sent to ISF to reduce it to Zn and Pb.



CHAPTER 9 ACID PLANT

ACID PLANT



The acid plant used for manufacturing the sulphuric acid is a traditional plant based on contact process for manufacturing the sulphuric acid. In the plant we have used following instruments in some fixed numbers as:

Absorption Towers (3):1. In the gas coming from the gas cleaning plant contains a significant amount of water

which is to be removed before it is allowed to enter to the catalyst chamber because water may destroy the catalyst. For that we must dehydrate it using a dehydrating agent. And the dehydrating agent frequently available in the plant is the Sulphuric acid itself. We pass the concentrated acid through the tower to absorb the water vapors in the gas. After passing through the tower the acid become dilute which is mixed with the concentrated acid coming from the other two absorption towers to maintain the concentration.

2. The second absorption column is used to convert the SO3 into Sulphuric acid. A spray of the some dilute sulphuric acid made from the top of the column and we are getting the concentrated acid from the bottom of the plant.

3. The third absorption column is used to convert the remaining SO3 into the Sulphuric acidusing the same method.The acid coming out of the last tower is approximately 98% pure. This acid is mixed with the acid coming from the other two towers to maintain the concentration. The amount of acid of each concentration getting mixed with one another is controlled from the control room

Reactors (1):

The reactor used in the sulphuric acid plant is contain a known weight of the catalyst Vanedium PentaOxide. The Sulphur Dioxide entering into the reactor get converted into the Sulphur Trioxide. The temperature at which the reaction is fastest is 450-620°C . So temperature from the control room is maintained between these limits. As the reaction is exothermic the temperature is maintained automatically inside the reaction vessel around the desired value. This is accomplished by taking out some amount of gas out of the column after each catalyst bed. When the gas is brought out first two times it is just cooled using the heat exchangers. But when gas is brought out after next two catalyst beds it is first through the heat exchangers and then through the absorption columns.

Heat Exchangers(6):

In plant we have total 6 heat exchangers which are being used to cool the gases coming from the reactor (On tube side). These heat exchangers are arranged in such a way that proper usage of the heat generated in the plant can be done.




Absorption Tower 1 Reactor

Absorption Tower 3

Absorption Tower 2

Cooler Heat Exchanger

To Storing Tank

Sim

plified Diagram

Of S

ulphuric Acid P

lant In Plan

t

O2

22


Specifications

Parameters ContentTotal Acidity (as H2SO4) 98.00% minResidue on ignition 0.050% maxIron Content (as Fe) 0.005% maxLead Content (as Pb) 0.002% maxArsenic content (as As) 0.003 % maxBulk density 1.840

End UsesSulphuric Acid is the bulk commodity chemical used by almost all the industries. It is the basic building molecule for chemical industry; used for different applications. The major consuming end use segments are:

Fertilizer (Phosphatic Fertilizers: DAP & SSP) Detergent Dyes & Dyes Intermediates Organic & Inorganic Chemicals Textiles Petrochemicals Refineries Pharmaceuticals Explosives Pulp & Paper Rayon Alum Manufacturing Sugar Refining Metal Pickling Electrolysis

EFFLUENT TREATMENT PLANT

The Effluent Treatment Plant can be divided into 5 sections1. Cadmium Removal2. Cyanide Destruction3. Fluoride Precipitation4. Heavy Metals Removal5. Lime Slurry Make-up

1. Cadmium Removal:



The Cadmium plant produces the effluent containing 40% cadmium. Therefore this Cadmium is precipitated before entering the main effluent treatment plant. The effluents are first mixed with 10% w/w slurry & pH is maintained at 11.5. The solids are taken to a sludge tank, which also collects sludge from the main plant. The over flow from the thickener flows into the primary reaction tank for the precipitation of the remaining heavy metals.

2. Cyanide Destruction:

Blow down from the ISF gas washing system is received into an agitated tank, where the pH is adjusted with a lime slurry. The pH is maintained at about 8. The effluent is pumped to a cascade tower prior to which the effluent is chlorinated with a vacuum ejector chlorine dosing system, at a rate of 0.825 kg/hr. The cyanide decomposes during aeration in the cascade tower,; the effluent is then pumped to the r treated effluent tank. The treated effluent is then pumped to the ISF gas washing system at a rate of 10 gm cu. M/hr. The excess treated effluent is channeled to the evaporation lagoons.

eaction tanks to precipitate heavy metals.

The clarified treated effluent overflowing from the thickener gravitates to a Cl2 (0.825 kg/hr)

3. Fluoride Precipitation:

Effluent from the gas cleaning plant is the main source of fluoride ion. In order to reduce the level of fluoride to an acceptable level in final effluent this stream is treated with milk of lime slurry to precipitate fluoride to 8 mg/l.


a+bISF Effluent Tank Chlorinator

Cascade Tower

Cascade Sump Tank

For Precipitation of Heavy Metals

24


The fluoride bearing stream is fed to agitated reaction tank where it is mixed with milk of lime from the ring main & the pH controlled at approximately neutral (pH 6-8). The resulting gypsum & calcium fluoride are filtered out on a plate & frame filter pres. A standby press is provided. The coke is manually discharged &dumped. The filtrate is pumped to the main effluent stream

pH 6.8For precipitation of HeavyMetalsFluoride Cake & Gypsum

precipitation of HeavyManually Removed

Heavy Metals Removal:

Effluent arising from the following sources are routed to either the primary or secondary reaction tank :

Sinter plant (Blue Powder Filtrate) Gas Cleaning Copper Recovery, Water Treatment, Boiler Blow Down (Launder &Power Generation), & Soft Water Circuit.In addition, intermittent wash-downs from the Acid Plant, Sinter Plant & Raw Material Handling &Intermittent arising from the Precious Metal Plant.The reaction vessel also receives the cadmium plant effluent & ISF gas washing effluent mentioned previously. The majority of heavy metals are precipitated in two reaction tanks by treatment with lime slurry & continuous agitation at a pH of 8.0& 10.5 respectively in first & second tank. The effluent & precipitated solids are taken to a 30metre diameter thickener.The overflow from the thickener gravitates to the third reaction vessel where the pH is adjusted to 9 by the addition of sulfuric acid (98%w/w). The underflow from the thickener is pumped to a sludge tank, which also receives cadmium sludge. This vessel is agitated to maintain the solids in suspension. The liquor in the third reaction vessel precipitates gypsum as the pH is lowered. This liquor is pumped for final clarification to a thickener where any solids removed are pumped to the sludge vessel mentioned above.The sludge collected in the sludge tank is pumped as a slurry, to the Blue Powder Thickener where it is further thickened & returned to the sinter plant.


aFluoride Reaction Tank

Filter Press

25


Lime Slurry LimeSlurry FeSO4

pH 8 pH 10.5

Overflow

pH 10.5 pH 9 pH 9

Underflow Underflow

Cd slu

5. Lime Slurry Make-up:

Lime of 80%CaO crude, received in 40 kg bags is transported by hand from the storage area to the lime mixing tank at a rate about 1.1 tonnes/hr. The bags are split open on a grid over the tank & mixed with treated recycled effluent water. The lime slurry is pumped via a transfer pump to a head tank, which supplies two sets of pumps feeding lime slurry (10% w/w) to the cadmium plant & effluent treatment plant ring mains

Overflow

Underflow


aPrimary Reaction Tank

Secondary Reaction Tank

Heavy Metal Thickener I

Heavy Metal Thickener I

Tertiary Reaction Tank

Heavy Metal Thickener KK

Overflow for Recirculation 245 m3/hr

Sludge Tank

Blue Powder Thickener

a+b+cCd Effluent Mixing Tank

Cd sludge Thickener

Sludge Tank

For Precipitation of Heavy Metal

26


CHAPTER 10 ISF PLANT

The imperial smelting blast furnace is designed to simultaneously produce molten zinc and lead by smelting prepared raw materials with preheated coke and preheated blast air.The prepared, agglomerated raw material (sinter) is fed to the top of a vertical shaft furnace together with the heated coke. Air is blown into the bottom of the shaft and the chemical reaction between this air and the coke produces carbon monoxide and generate heat to smelt the metallic oxide in the charge into the elemental metal. Molten lead falls into the bottom of the furnace from where it is tapped together with slag of a molten gangue material. At the temperature of operation, metallic zinc is formed as a vapor and rises up the furnace shaft with the furnace gases. These zinc containing gases pass through a furnace off take into the condenser containing molten lead. Here zinc is condensed to a liquid by shock cooling, the gases with a spray of finely divided droplets of lead generated by rotors immersed in the lead. After absorbing condensed zinc, this lead is pumped out of the condenser into a adjacent cooling launder where it is cooled by tube banks immersed in the launder from above. At the end of the launder the zincy lead is treated with flux and flows into a separation bath where, at the cool temperature of 440 deg cent., zinc separates as a molten layer on the top of lead. Zinc continuously overflows via a V- notch into a adjacent liquation bath whilst the main lead stream passes from the separation bath under the underflow weir and then into a return launder leading back into the condenser.

The liquation bath is small bath in which any final separation of lead and iron from the zinc can occur before the zinc overflows to the final holding bath. Here it is allowed to accumulate before being tapped for casting or further treatment in zinc refinery.The waste gases leaves the condenser after zinc is condensed from them are passed into a gas cleaning system where they are cooled and cleaned of particulate matter. These gases contain carbon monoxide and have a low calorific value. After cleaning calorific value is utilized in preheating the furnace blast air and in preheating the coke; any remaining excess gases is used in the site power plant boilers.




Coke Preheater

Cowper Stove

Gas Cleaning Section

BP Thickener In ETP

LCV gas

Slag to Yard Force Hearth Furnace

Separ-ation Bath

Liquati-on Bath

Holding Furnace

Furnace Zinc to ZRP

Lead Bullion to LRP

Imperial Smelting Furnace

Pump Sump

CoolingLaunderng Launder

Sinter+Hot Coke

Hot Air

Zinc Vapour

Lea

d

Hot

Gas

Hot Air

Coke

28


FURNACE

The ISF consists of three sections-the upper section ( or furnace shaft) which contains furnace gases off take, and intermediate section with a shower cooled casing and the lowest section- the furnace hearth. All three section are joined together to give a gas tight construction in which the charged is smelted.The sinter and coke are fed into the shaft though two sets of charging gears situated in the furnace roof and blast air enters through tuyeres set in the lower portion of shower cooled casing. Lead and slag are tapped from the furnace hearth and furnace gas and zinc vapor leaves the shaft through furnace off take which is set in one side above the top level of charge

CONDENSER:

Zinc condenser is essentially a refractory lined steel tank containing molten lead with a gas above through which furnace off gases are passed. Furnace gas enters the gas space from the furnace off take and flow through the lead spray in three condensation stages before leaving the condenser through the vertical off take stack at the rear. The condenser has a shallow inverted arch refractory floor and a demountable shallow arch roof formed from cast iron and mild steel tiles. It is divided into three sections by vertical steel baffles to form three distinct condensation stages. In each stage steel baffles are there to form three distinct condensation stages. In each stage vertical rotor units are suspended from above with the rotors immersed below the normal lead level. The rotors are designed to throw the spray of lead droplets into gas space in order to condense zinc vapor contained in the furnace off takes.The condenser gas off take is a regular refractory lined stack fitted with internal liner plates. The gas pass up the stack before leaving through a doubly inclined cross over duct leaving to the gas washing tower. The off take stack is provided with doors in prder to provide facility for cleaning.

LEAD COOLING AND METAL SEPERATION SYSTEM

Hot lead delivered from the condenser lead pumps is cooled so that dissolved zinc separates as a second liquid phase and floats of the lead from where it can be removed by physical separation. Cooled lead reduced in zinc contents is returned to the condenser so that it can condense more zinc from the furnace gases.The metal separation system consists of two connected baths between the cooling launder and the return launder to the condenser, and two baths which form a side stream route for the zinc output metal.As lead enters the flux bath about 20 kg per hour of ammonium chloride pellets are added from the hooper and feeder system. This flux is added to minimize turbulence and the oxidation of zinc. The lead enters into a section from which it flows out over a submerged baffle, this arrangement being adopted to ensure that the ammonium chloride is thoroughly mixed into the



lead and that dross is brought to the surface. The flux bath is roofed and the point of flux addition is hooded for ventilation purpose. Lead flows out of the bath via an underflow weir to prevent dross carry over to the separation bath.From the liquation bath zinc overflows to the zinc holding bath which is a surge bath allowing zinc metal output to accumulate before being tapped into ladles or moulds from transfer to zinc refinery. This bath also provides a facility for reheating molten zinc to between 480 to 520 deg cent.which is temperature required for further handling.At the separation bath, zinc overflows the V-notch and falls into the liquation bath. The purpose of this small bath is to provide facility for removal of impurity from zinc to maintain the grade of zinc passing to the zinc refinery. Iron is removed in the hard metal which gradually forms a layer under the zinc as is cools. Lead carry over and settle in this bath and may be tapped and removed from time to time for return to cooling launder as lead ingot.All the baths of the metal separation system are of a refractory lined metal casing construction, have removable refractory lined roof tiles and are fitted with a burner and cleaning rods. In the sides of the bath, refractory tapping blocks allow metal to be drained out when required. All baths are provided with ventilation ducts which passes through the roof tiles and ventilation hoods are provided over the dross discharge areas.

GAS WASHING PLANT AND LCV DISTRIBUTION SYSTEM

Introduction

The purpose of these systems is to cool the condenser off gas, to remove particulate matter and to produce and deliver a clean, low calorific value gas suitable for burning in coke preheaters, cowper stoves and power generation plant. The particulate matter, containing zinc and lead oxides and other fine particles carries over from the furnace(blue powder) is washed out of the gas and collects as a slurry for subsequent thickening and return to sinter plant.Gas cleaning is accompanished by a preliminary cleaning and conditioning operation in a unpacked co current spray tower, followed by scrubbing in a special high speed irrigated fan known as disintegrator. Water droplets are then remove from the gas in a cyclonic separation and the gas pressure is booted for distribution to the gas consumers.The dirty liquor drains to a dredge tank from which it is collected for pumping to a thickener. This tank is 15m long and run under the three units, gas washing tower, disintegrator and moisture separator. It serves both as water seal and as a slurry collection tank for each unit.

LCV GAS DISTRIBUTION

The function of this system is to distribute the cleaned LCV gas from the outlet of the moisture separator to the three major consumers, or to release from the system via the flare stack at periods of low consumption.



The gas booster fan is used to control the pressure in zinc condenser and the gas washing system and to deliver gas at the required pressure into the LCV gas header main for supply to cowper stoves, the coke preheaters and the boilers of the power generation plant.DREDGE TANK AND BLUE POWDER DISPOSAL

The dredge tank forms a reception tank for the drain from the component of the gas washing system, and also acts as a water seal for all the down comers. Scrubbing water drain into the tank carrying with all solids scrubs from the condenser gas. The heavier solid particles settles to the bottom of the tank while the major part of the liquor carries away the smaller suspended particles and flows over a weir on the side of the tank into a line leading to a blue powder pump tank.At the blue powder slurry pump tank two slurry pumps, one operating and one stand by, pumps the blue powder suspension onto a high level open launder leading to blue powder thickener. Pumps also discharge liquor from the blue powder sump and the blue powder slurry tank to the launder. Lump material from the lump bunker is moved to the sinter plant



CHAPTER 11 ZRP

This Plant is also known as1) Zinc and Cadmium Refinery2) Zinc Refluxing Plant

Objective of refining

The I.S.F. zinc is not suitable for zinc’s prime user i.e. galvanizers due to1) High cadmium percentage2) Occasional high arsenic

Hence zinc produced from I.S.F. needs a suitable refining to become of economic industrial use. The process followed in CLZS is by distillation in “new jersey type distillation columns

The Plant

Zinc refinery is situated east of I.S.F. the basic engineering is given by mechim-engineering of Belgium and process by novellas-godault of France. Main construction is done by TATA DAVY LTD.

Some Special Features:

1. Since the main refining is done in columns consisting of superimposed silicon-carbide trays, the trays can’t take thermal shock, so the process can’t be stopped more than 2-3 minutes. Only after the life (2 to 3 yr) of the columns finishes can be stopped. So the equipments which are responsible for feeding and heating must run 24hr/day.

2. Due to above reasons, there are some conditions before start up. Otherwise huge expenditure & time will be taken to rebuilt the trays consisting columns.



Properties used in refining metals:

FLOW CHART OF ZRP


Zn Pb Cd AsMelting point 419.5c 327 320.9 616Boiling point 907c 1740 767 815Specific gravity 7.14 11.40 8.65 5.73Atomic no. 30 82 48 33Atomic weight 65.37 207.19 112.4 74.92

Furnace Zinc from ISF

Caustics Sodium Soda Nitra

33


MAIN PROCESS WISE UNITS:

1. I.S.F. ZINC HANDLING UNIT2. EMERGENCY CASTING UNIT3. MAIN WORKING UNIT4. CASTING AREA5. RECUPERATOR UNIT6. CADMIUM REFINERY7. L.P.G. AIR MIXING UNIT8. OIL HANDLING STATION9. BLOWER HOUSE AND BURNER10. FUME EXTRACTION SYSTEM11. BUILDING VENTILATION12. STORES

PROCESS DESCRIPTION

The I.S.F. Zinc is feed to the storage f/c through tilting device or by the loading door in form of 1.1T ingots. This Zn by gravity goes to the feeding furnace. In emergency 1 zinc pump is used or ladles are tilted in the feeding f/c directly. The feeding furnace through the needle valve and float valve feeds the I.S.F. Zinc to the lead columns in requite amount and temp. The lead columns which have 59 trays each are having two parts up to the 30 th tray. It is having a combustion chamber around it and is known as the boiling part. The top portion above the 34 th tray (feed tray) is insulated, it is the refluxing part. Only during the start up this top part of lead columns are electrically heated. If we consider the column erected by superimposition the trays, has got 8 types of trays. The top tray is different as it is connected to the condensers by a mass-rack (electro-fused silica) cross over the bottom tray, the feed tray, the tray above feed tray. The 30 th

tray is having double opening and extra electric coils around it. 33rd tray is having different outer shape. All the rest trays are of 2 types:

1. flat type: located in the reflux part2. w-type: located in the bottom part(boiling part)

If we consider the composition of I.S.F. Zn and see the action of combustion chamber which is having 8 burners in each column drawing 10% of total combustion air from the burner and the rest 90% preheated air from recuperator, we find that full cadmium, half Zn vaporizes and full lead and half Zn comes down. The top product is condensed in condensers of each lead column and then again in hot condition they are fed to cadmium columns. Feed system is same as lead columns. Here the number of trays are 56 only and 2 columns are there ( rest everything is same for cadmium columns) . this feed is known as Zn-Cd alloy. The bottom products of lead columns are collected through sump which has an air lock type overflow system. This is Pb-Zn alloy having extra lead. This Pb is separated in liquation f/c. some hard Zn also comes and rest Zn having only the minimum lead comes out as G.O.B. Zinc i.e. good ordinary brand or prime western (PW) zinc. The top Zn-Cd alloy is separated in cadmium columns. The bottom product of this is very high grade Zinc known as special high grade zinc (SHG).



The top product after condensation becomes Cd-Zn enriched alloy and is casted in moulds to be sent to Cd refinery. The SHG & GOB are casted in separate casting m/c.

Main difference between lead and cadmium columns:

1) The feed tray is 34th for lead columns & 36th for cadmium columns.2) After the 36th tray cadmium columns are having baffles inside the trays.3) There are no electrical heating systems for cadmium column top portion, it unlike lead

columns behave as condenser also.4) Total no. of trays for LC is 59 & CC is 56 each.5) Condenser size is small for cadmium columns.

Both types of columns have attached recuperator system for energy conservation. The I.S.F. Zn is stored to ensure a constant feed but in case this 1.1T ingot stock fails, we have recirculation facility of GOB zinc through 4T shaft way using one demag monorail hoist. 0.5T shaft way is also there for bringing ingots to the top floor. Weighing m/c is used to weigh the ingots before charging. Some Zinc from cadmium refinery comes in form of 0.5T ingots to be melted in storage f/c. the lead from liq. f/c is sent to lead refinery and hard zinc to I.S.F.. All other dross is also sent back to I.S.F.

PROCESS PARAMETERS

A) Storage furnace

1. bath area: 18 square meter2. free metal: 70 T3. fixed metal: 40T4. total metal: 110T5. metal content: I.S.F. Zinc6. metal flow: 286T/Day (same as feed) 208T/Day (when ingots are used)7. metal feeding temp.: 480 – 520^c8. bath temp.: 5509. burners each of: 400000 kcal/h

(Triple fired i.e. L.D.O/LSHS/LPG)



B) Feeding furnace

1. bath area: 6.6 square meter2. metal flow: 286T/day3. metal content: I.S.F. Zn4. metal feeding temp.: 5505. bath temp.: 55-6706. feeding quantity: 282T/day7. burners one of: 600000 kcal/h

B) Lead columns(LC,LC2,LC3,LC6)

1. combustion chamber: 14 square meter2. metal flow: 95T/day3. top flow (vapors): 38T/day4. bottom flow: 57T/day5. top outlet temp.: 850/9506. incoming temp.: 550/6707. bottom outlet temp.: 750/8508. condenser capacity: 1square meter/ton of Zn condensed

(Natural induced air type)9. expected life: 2.5 yrs10. burners 8 each: 250000kcal/h

(Triple fired)

C) Cadmium columns (CC4 & CC5)1. metal flow: 57.5T/day2. metal content: top: Zn-Cd alloy enriched Bottom: SHG Zn Feed: Cd-Zn alloy3. top outlet flow: 2.5-3T/DAY4. bottom outlet flow: 54.5-55T/day5. top outlet temp.: 850/9506. bottom outlet temp.: 750/850T/day7. incoming feed temp: 550/670T/day8. combustion chamber: 14 cubic meter9. burners (triple fired): 8 no. each 200000kcal/h



D) Liquation furnace:1. bath area: 1.25 square meter2. free metal capacity: 103T3. minimum metal capacity: 25T4. metal flow: 164T/day5. metal content: Pb-Zn alloy6. metal feeding temp.: 430/4507. bath temp.(reheating part): 480/5408. burners each having: 200000kcal/h

E) GOB holding f/c:1. bath area: 26 square meter2. free metal capacity: 103T3. minimum metal capacity: 25T4. metal capacity(total): 128T5. metal flow: 161T/day6. metal content: GOB Zn7. metal feeding temp.: 4758. bath temp.: 475/5409. burners(2 no.): 400000kcal/h

F) SHG holding furnace:1. bath area: 17.8 square meter2. free metal capacity: 71T3. fixed metal capacity: 17T4. total metal capacity: 88T5. metal flow input: 120T/day6. metal content: SHG Zn7. metal feeding temp.: 4758. bath temp.: 475/5409. metal flow(outlet): 120T/day24h/day10. burners (2 no.): 400000kcal/hr



CHAPTER 12 LRP

OPERATION IN LEAD REFINERY

Lead refinery can be subdivided into two sub sections for ease of understanding1. Copper drossing area2. MTM Refined lead production area

COPPER DROSSING AREA

In this area the copper is removed from ISF bullion in two stages.The area consists of five kettles, each of 100 MT capacities, out of which two are enmarked for first stage of copper drossing, or hot drossing and others are used for second stage of copper remove, or cold drossing. In fifth kettle, lead bullion from the Ausmelt Plant is charged.

HOT DROSSING

ISF lead ladle is received in lead refinery by means of 15/8 MT E.O.T. crane. The ladle is placed on a hydraulically operated ladle tipper which raises the ladle to pour molten lead into hot drossing kettle. The kettles are provided with hoods with opening for stirrer and dedrosser. The hot drossing kettle is filled up to capacity and temperature of the bath is brought down to 450 deg. Cent with the stirrer running. As the temperature goes down, solubility of copper in lead decreases resulting in separation copper from the bath. The copper so separated forms a dross on the surface of the bath owing to its high melting point and low specific gravity then the bath. A little quantity of saw dust is added into the bath to make the dross dry. The dross is then removed from the kettle by means of a mechanical dedrosser and is taken into skips. The copper dross is then transferred to copper recovery plant for recovery of copper.

COLD DROSSING

The bath is then transferred to either of the two cold drossing kettles. Here temperature is brought down to 330 deg cent and a calculated amount of sulphur is added depending upon copper content of the bath. Sulphur reacts with copper to form copper sulphide which floats on the surface of the bath. This dross is removed manually into skips and is recharged into hot drossing kettle. Copper after cold drossing is around 200 gpt. The Decopperised lead is then transferred to MTM refined lead production area for further treatment.



LEAD\SILVER REFINARY FLOW CHART

De-Arsenic

De-silversitation

Vaccum De-zincing

Antimony Removal

Final Refining

Casting Machine

Copper Dross CRP

Arsenic Dross to Sinter Plant

Zn-Ag Crust

Liquation Furance

Vaccum Retort Furance

BBOC

Pyro Ag(98.5% min.)

CuSO4 SolnSaw Dust Sulphar

Zinc

Zinc

Low

Gra

de L

ead

Caustic Soda

Caustic SodaSodium Nitrate

Antimony Dross

Refined Lead>99.99%

OxygenNitrogen

Copper Drossing



MTM REFINED LEAD PRODUCTION AREA

DEARSENATING

Decopperised bullion is received in 150 MT capacity dearsenating kettles via a transfer pipe. The temperature of the bath si raised to 459 deg cent and 100 kg of caustic soda is added and which react to form sodium arsenate and which in the form of dross floats over the surface of the bath. Once dross is formed, it is removed by mechanical deedrosser into skips. The dross is then sent for treatment into rotary furnace. Dearsenate bath is pumped into desilverization kettle.

DESILVERIZATION

Desilverization is carried out in two stages, each kettle of 180 MT capacities.

Dearsenated lead is received into first stage desilverization kettle at 450 deg cent. The kettle has a lead of Pb-Zn-Ag alloy from the previous charge. Poor silver zinc crust from previous batch of second stage of desilverization and low grade metal from liquation kettle in silver recovery area are added into this bath. The bath is thoroughly homogenized with the help of a mixer. Zinc and silver present in the bath forms intermetallic compound which floats on the surface of the bath in the form of crust. The crust, called rich crust is skimmed of f by means of perforated crane skimmer and cast into moulds for treatment in silver refinery. Once crust have been removed a calculated amount of zinc is added to the bath depending upon its silver content, zinc is melted, bath is homogenized and the bath is pumped into second stage desilverization little. When the bath is received into second stage de-Ag kettle the little already contains a crust bridge across the kettle with the central opening in it. Upon receiving the metal, thorough mixing is done and the crust bridge is homogenized with the bath. At 450 deg cent again a crust formation is there e which is lean is silver. The crust is skimmed off into the moulds for charging into De-Ag first stage kettle in succeeding charge. After removal of crust bath is allowed to cool with central mixer running at very slow speed. As the bath cools down, solubility of bath zinc and silver comes down and these elements separate from the bath and come to the top in the form of crust. As the crust melting point is higher then the bath, the crust solidify over the bath. The kettle is cooled to 325 deg cent, at this temperature mixture is removed and the pump is placed in the central opening of the solidify crust and the bath is transferred to next kettle for dezincing.

VACUUM DEZINCING

This kettle is of 150 MT capacities and has a water cooled rim over it. In this kettle temperature is raised to 590 deg cent and a vacuum dome is placed over the kettle. On the underneath of the dome there is a solid rubber ring which sits over water cooled rim to make the system vacuum proof. For dezincing vacuum pump is started. At this vacuum zinc in the bath get vaporized and get deposited over the bottom of the water cooled dome. The operation is carried over in two



stages of four hours each. At the end of the operation the dome is lifted away and zinc deposited is scrapped off. The dezinced bath is then transferred to first stage.

SOFTENING

The dezinced bath is received in 150 MT capacities for the removal of antimony. The removal of antimony is cooled softening. Here in addition to antimony residual zinc, arsenic etc are also removed.In this kettle caustic soda and sodium nitrate are added at a temperature of 440 deg cent. All the impurities get oxidized and floats in the form of dross. This dross is removed by mechanical dedrosser and sent for the treatment in rotary furnace. Then this lead is transferred for casting. In casting condenser kettles are there in which lead condenses. Condenser lead is consumed by ISF plant.



The Imperial Smelting Furnace used in the production of lead and zinc produces by-product drosses from the ISF bullion floor which are rich in copper and lead. These drosses are treated in copper recovery plant by a process developed by Imperial Smelting Processes Limited. Drosses receiver from the copper drossing kettles are ground and screened and over sized material which are predominantly lead, returned to kettles.The drosses are treated in a stirred batch leach reactor by an aerated of ammonia liquor and carbon dioxide. Copper is dissolved and removed as cupra ammonium carbonate. After leaching, the slurry is filtered in a filter press and the leachant passed to leachant tank. Lead is present as a mixture of lead oxide and lead carbonate in the filter cake, the lead content being approximately 70% on a dry weight bases. The filter cake is slurried and returned as approx 50 % w/w slurry to the sinter plant.Leachant is further filtered before treatment by solvent extraction to recover the copper. Copper is extracted with LIX 54, a copper specific diketone liquid ion exchange reagent in hydrocarbon diluents, in two stages of mixture settler. The depleted aqueous phase or raffinate, containing approx 1.5 g/l copper recycled to leaching circuit for reuse in leach reactor.The loaded organic is washed with dilute sulphuric acid to remove impurities before being stripes with depleted electrolyte to remove copper. The copper enriched strong electrolyte passes to electro winning section in which cathode copper is produced by electrolysis of the acid copper sulphate solution.

SOME PARAMETER OF MILLING:

Temperature of feed 70 deg cent (max)Temperature of product 60 deg cent (max)Size of feed 80 % - 5 mmProduct size 80 % - 75 micronBall mill capacity 2 tonnes per hourMill running time 15 hrs/day

DROSS MILLING:The function of dross milling circuit is to grind back hoe dross to 80 % finer than 75 micron. Simultaneously as much metallic lead as possible is rejected to return to drossing kettle. Dross is received as back hoe dross for milling and also as fine dross from the drossing section bag house.

GRINDING CIRCUITThe mill is a hardinge conical ball mill, air swept in close circuit with double cone separator and vibrating screen. The mill has an overflow discharge into an air stream,. Coarse metallic fails to be transported by the air stream and will drop out into a drag link conveyer.The ground material carried up by the air stream is classified in the double cone separator. The coarse fraction is screened on a double deck vibrating screen. Coarse dross is recycled to the mill through a air lock. The cyclone overflow returns with the main air stream to the mill. The cyclone underflow forms part of the ground dross product. A bleed form the exhauster fan delivery is fed to the mill bag filter. Dust recovered from this unit is also fed to the ground dross



product. The mill feed is controlled automatically to maintain the correct mill load by an audio signal from the mill.

FINE DROSS HANDELINGAll fine dross, consisting of ground dross, bag house dross and dross from the hygiene bag filter, is also fed to the ground dross storage bin. Ground dross and hygiene bag filter dross are fed directly into the ground dross bin. Dross is discharged from the ground dross bin by a rotator feeder into a bell hooper resting on a rail mounter trolley. A forced seal is made to prevent egress dust during loading. The rotatory wall is operated by a timer to enable a reasonable consistent volume of dross to be loaded into the bell hooper. The bell hooper is pulled clear of the storage bin by a winch. The copper leach crane, fitted with a crane weigher, is used to transport the bell hopper in between the dross milling section and leach reactor. Nine transfers of fine dross to the leaching section are done per day. The copper recovery plant is divided into following plant area

Area K2 Dross MillingArea K3 LeachingArea K5 Solvent ExtractionArea K6 Electro winning

Area K3 Leaching

The leach reactor extracts copper from the dross produce in decopperising kettle. In leaching fine dross is leached with CO2, H2O and ammonia to form cupra ammonia carbonate which contain copper approx 10 gpl

The designed criteria:Dross treated 9369 t/aCopper production 2100 t/aCopper content in dross 32.2 %Leach efficiency 90 %Batch leach time 4 hrs approx.Batch dross quantity 3.25 tLeaches per day 9A typical feed stock dry analysisCopper 32.3 %Lead 50 %Zinc 3.5 %Arsenic 1.3 %Antimony 2.4 %Tin 0.3 %Silver 0.1 %Bismuth 0.025 %Gold 7.25 g/tSulphur 1.3 %



Copper is extracted by reaction with raffinate (ammonia carbonate solution) returned from solvent extraction plant.A typical raffinate analysis is:Copper 1.5 g/lAmmonia 30 g/l approxCarbon dioxide 20-30 g/l

Ammonia RecoveryIt is essential for environmental, health and economic factors to minimize the loss of ammonia and maximize the recovery for reuse in the process.The ammonia recovery plant:

1. Provide ventilation for all areas in which ammonia bearing solution are handled2. Recovers ammonia from the ventilation gases by scrubbing.3. Recovers ammonia from the wash section for recycling4. Produce an effluent suitable for disposal to the site effluent facility5. Maintain in plant conditions below the TLV.

All ammonia bearing gas stream are scrubbed with water to produce a acceptable stack discharge. The mildly ammoniacal water is then used for the final washing of the filter cake before passing to the wash storage tank.Ammonia bearing gases are streamed are scrubbed with water to produce a stack discharge not greater than 25 ppm ammonia. Absorber water is used for the final washing of the filter cake in order to maximize the water utilization.All the ammonia bearing liquid streams, including bleed stream from the LIX wash and electrolyte circuit are collected in the wash storage tank. The composite wash is treated by the solvent extraction to remove any copper present prior to neutralization with caustic soda in the caustic soda treatment tower where the pH is raised to 11 to liberate ammonia.

Solvent ExtractionThe solvent extraction plant process 12.5 m3/hr of leachate (cupra ammonium carbonate solution) containing approximately 30 gm/l Cu+2. Copper is transferred from the leachate to thebarren electrolyte by proprietary copper specific ion exchange reagent LIX 54 diluted with Escaid 100 ion exchange diluents.A typical leachate analysis is :Copper 30 g/lAmmonia 30 g/lCarbon dioxide 23-30 g/l



APPLICATIONS OF Zn , Pb AND PRINCIPAL BY PRODUCTS

Some of the common uses of these metals are given below:

ZINC: The main uses of Zn are in galvanizing for protection of steel against corrosion, alloy making (brass, bronze and bearing metals) dry cell batteries, die castings for automobiles parts, business machines & toys. Oxides & sulphides of Zinc are widely used in paints &rubber industries. Zinc dust is used for metal coating &as reducing agent for many chemical processes. Zinc sulphate is used as an important micronutrient for soils.

LEAD: The main uses of lead are for storage batteries in transportation, ammunition, in defense, lead protection for cables, chemical equipment, pigments &paints. Lead is also used in bearing & soldering alloys, type metals, fusible alloys, in sound & vibration insulations, shield against X-ray & nuclear radiations & as ballast weight.

CADMIUM: Cadmium is used for pigments, electro-plating steel for improved corrosion resistance, solders, brazing &bearing alloys, rechargeable batteries &nuclear control rods. It is also used for plastic stabilizers and semiconductor materials.

SILVER: The important industrial uses of silver are in photography, electrical switches, batteries, stabilizers & in bearing alloys .Silver is extensively used for jewelry & coinage.

TUNGSTEN: Tungsten has become indispensable in strategic & industrial uses particularly in defense armaments. It is mainly used in tungsten carbide tools, electrical bulbs &other electronic applications, alloy making, chemical etc.

COBALT: It is used in manufacture of magnets, high speed steel & as a binding agent for the manufacture of cutting tools, mining drills etc. This metal is also used in super alloys for industrial &air-craft gas turbine engines. Its non-metallic applications are pigment in paints, ground coat in porcelain enameling, and coloring agent in glass & essential ingredient in some catalysts.

SULPHURIC ACID: It is a basic chemical required for manufacture of chemicals & fertilizers.

PHOSPHORIC ACID: It is mainly used in the manufacture of complex phosphatic fertilizers, detergent, food preservatives & as pickling agent.These metals have amazingly wide spread use in our day to day life also. Be it a ball point pen or a fountain pen, a small tea-spoon to a big water heating boiler & all other utensils for boiling & cooking , dry cells for torches , radio transistors, tape recorders, calculators, watches & many other electrical & electronic gadgets ; wet batteries for cars & other automobiles, G.I. sheets , pipes, pesticides , fertilizers & many other things which come into use in our daily life, have zinc &lead component or their alloys along with other metals.



MISCELLANEOUS PICTURES OF PLANT

FINISHED BRICK OF ZINC CAM FOLLOWER MECHANISM

CONVEYOR AT ZRP PACKAGED ZINC READY TO SELL



TOPPLER MACHINE TO TOPPLE RAIL BOGIES


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