SUCCESS STORY REPORT

FOR

LEAD ACID STORAGE BATTERY

MANUFACTURING, SECONDARY LEAD

SMELTING & PROCESSING SECTOR

MARCH 2011

Prepared by : Ruby Sinha, Environmental EngineerWest Bengal Pollution Control Board

Prasun Kr. Mondal, Assistant Environmental EngineerWest Bengal Pollution Control Board

Edited by : Amitava Ray, AECEN India Representative

Published by : Subrata GhoshChief Engineer, West Bengal Pollution Control Board& Nodal Officer, Environment Compliance Assistance Centre

Printed by : S. Antool & Co. Pvt. Ltd.91, A. P. C.Road, Kolkata-700009

1. INTRODUCTION 4

2. OVERVIEW OF LEAD ACID BATTERY MANUFACTURINGPROCESS

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3. VISIT TO HBL POWER SYSTEMS LTD 7

4. CLEANER TECHNOLOGY OPTIONS ADOPTED BY HBL POWERSYSTEMS LTD

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5 SECONDARY LEAD SMELTING SECTOR 13

6. CONCLUSION AND WAY FORWARD 14

7. PHOTOGRAPHS

TABLE OF CONTENTS

A. Introduction :

The Environment Compliance Assistance Centre in West Bengal has selected four SME sectors to

identify the environmental compliance related problems and also to document the success stories in

these sectors in other states of our country. Lead-acid battery and secondary lead smelting sector is

one of these identified four sectors. A two member team of the WBPCB visited the state of Andhra

Pradesh to study the success stories in this sector. The team visited the industry of M/s. HBL Power

Systems Ltd. in Hyderabad which is a pioneer in the field of battery manufacturing.

The use of battery has been increasing as time is passing. The increasing usage is proving its

importance and role. Batteries are gift of science which are given to men. The benefits and

advantages of battery is numerous and countless. These are the real companion of men in today's

world. No one can deny the leading role of battery.

Principal application area of lead is lead- acid batteries which account for about 60% of total

consumption. Lead is produced from primary raw materials as well as secondary raw materials.

The generation of lead bearing scraps/wastes increases with increasing use of batteries. The

importance of secondary lead plants is increasing day by day because lead being a hazardous

substance, recycling from scraps/wastes is the best way to protect the environment from pollution.

Exposure of lead from which battery is made is the primary health concern in battery

manufacturing. Any operation in which battery plates, lead scrap, or oxide is handled may be a

significant source of lead exposure. Airborne dispersion of lead dust via cross drafts, pedestrian and

vehicular traffic and dry sweeping may be an additional source of lead exposure. Lead fumes from

lead pots, torching, burning or other operations where a flame contacts lead, or lead is heated above

the melting point, may also be sources of lead exposure. Controlling the exposure to lead can be

done through engineering controls, administrative actions and personal protective equipments.

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B. General Manufacturing Procedure in Lead Acid Battery Units:

A battery is an electrochemical cell (or enclosed and protected material) that can be chargedelectrically to provide a static potential for power or release electrical charge when needed.

A battery generally consists of an anode, a cathode and an electrolyte. Lead-acid batteries, inventedin 1859 by French physicist Gaston Planté, are the oldest type of rechargeable battery.

Basic structure of a Lead Acid Batteries are:

i) Positive Plate ii) Negative Plate iii) Electrolyte iv) Separator and other passive components liketerminals, lids, container etc. The plates are made up of g rid / spines from pure lead or alloy oflead, in which active materials are held in the interstices and take part in the chemical reaction tosupply the energy. The grids or spines are produced through the casting process.

A typical process flow chart of lead acid battery manufacturing is given below:

Process Flow Chart of Lead Acid Battery

C. HBL Power Systems Ltd., Mehboob Nagar, Hyderabad:

State Board Officials visited the unit of M/s. HBL Power Systems Ltd. at Mehboob Nagar,

Hyderabad. HBL is one of the leading manufacturer and supplier of a wide range of batteries. These

batteries are widely used for telecom, aviation, automotive, railways and industries.

This unit manufactures Pb-acid battery. The unit comprises of 77 acre land, out of which one third is

greenery. Unit runs generally in two shifts in a day. Pb ingot and Pb dross are used as main raw

material which are purchased from India, China, South Africa. This unit has production capacity of

1000 batteries per day.

Different types of lead acid batteries are :

Flat plate VRLA

Pure Lead-Tin VRLA

Tubular gel VRLA

Ultra low Maintenance Tubular

Miners Cap Lamp

The unit is an integrated battery manufacturing unit. The unit has its own battery container

manufacturing division as well as used battery recycling division to ensure safe reuse/r ecycle of lead

scraps that are generated from the used batteries.

This unit has following divisions :

1. PMD (Plastic moulding division)

Virgin granules of ABS, PP, LDPE, HDPE are used as raw materials for manufacture of Pb - acid

battery container. Process is raw material dehumidification, charging into screw barrel cylindrical heat

chamber and finally moulding. This section has capacity of 660 T/ 19 machines. Product rejection is

1.5 – 2 % which are also reused.

2. Preparation of MS box container from MS sheet

Mild Steel (MS) containers of the battery are manufactured at the unit from MS Sheet using semi

-automatic welding machines. Production capacity is 40 nos.containers/hr.

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3. Powder coating division for MS container

Stages are as follows -

i) Degreasing – by Meta Clean ( a biodegradable surfactant) at a temp. of 70-800 C andresidence time of 10-15 min.

ii) Water rinse – Process pH is 7-9 at ambient temp. with residence time 1-2 min.iii) De rusting - by Phosphoric acid at ambient temp. having residence time 5-10 min.iv) Water rinsing - Process pH is 5-7 at ambient temp. with residence time 1-2 min.v) Activation – by Refine 2/2 at pH 8.5-10, and at ambient temp. with residence time 1-2 min.

vi) Phosphating – by zinc tri phosphate( Phosband 511T) at a temp. of 50 -550 C and residencetime of 5-10 min.

vii) Water rinsing – by DM water at pH 5-7, and at ambient temp. with residence time 1-2 min.

viii) Passivation – by acidic liquid chemical (Passtreat) at pH of 4-5 and at a temp. of 65-750 Cand residence time of 1-2 min.

ix) Dry off ovenx) Powder coating into an enclosed chamber where APC device is multicyclone .

xi) Curing oven – temp is 2000 C.

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The Steps are -

i) Pb plates are used as (+) ve and (-) ve electrodes. In between separators are applied.

ii) Charging points are welded on to lead plate by LPG welding.

iii) Plate assembly are welded by automatic squeeze welding.

iv) Plate assembly are kept within plastic container and heat sealing is applied.

v) Leak testing of container is done.

vi) Electrolyte (sulphuric acid) filling for cell formation. To control cell temp. batteries are

dipped into water bath for 96 hrs.

vii) Automatic gel filling into battery in acid : silica gel proportion of 10 : 1.

viii) Charging, discharging and capacity testing – 120 batches are charged at a time as one batch

contains 20 batteries.

5. Metal recycling section

HBL has its own used battery recycling division. Initially, manual separation of plastic and Pb metalare done from the waste batteries. Then the metal part is sent to smelting and refining section.

a) Smelting section -

The unit has 3 nos. F. O. fired rotary furnace. Each has capacity of 1 batch / day. 1 batch is 5 T metal.

1 batch takes 7 -8 hrs. In furnace, scrap metal with charcoal are charged through front manhole.

Battery assembling unit

Product is taken out through bottom manhole. Fumes coming out from the furnace enters into settling

chamber, heat exchanger, cyclone separator, bag house and then stack of height of 30 m from G L.

b) Alloying section -

Unit has 4 nos. F. O. fired vertical refining melting pot. Each pot has capacity of 10 T/batch. Each

batch takes 24 hrs. Top fumes are drawn into water scrubber, ID fan and finally stack of height 30 m

from GL.

6. Pb sub oxide

Molten Pb at 4500 C is pumped into top covered vessel fitted with agitator. Product is collected from

cyclone, and bag house with the help of ID fan.

7. Red lead unit

Unit has 2 nos. red lead furnaces. Lead sub oxide powder is charged into HSD fired brick lined

furnace fitted with agitator. The furnaces are provided with water scrubber, ID fan and finally stack of

height 30 m from GL.

8. Effluent Treatment Plant

Effluent is generated from acid, acid- gel filling , cell formation, gel preparation, acid preparation,

floor washing activities. The unit has installed a full-fledged effluent treatment plant alongwith

R.O.Plant. The treated water from the R.O. Plant is reused.

The ETP consists of the following components:

i) Grit Chamber

ii) Holding tank

iii) Settling tank

iv) Neutralization tank

v) Stabilization tank

vi) Sand and activated carbon column filter

vii) R.O. Plant – 13 KLD water which is recycled and RO reject is sent to double effectevaporator system.

viii) Double Effect Evaporator – produces 12 KLD condensate which is cooled and reusedas process water. Concentrate from DEE is 1 KLD which is treated as hazardous waste.

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cannot keep up with gas evolution. Since VRLA batteries do not require regular checking of the

electrolyte level, they have been called Maintenance Free (MF) batteries. However, VRLA cells do

require maintenance. As electrolyte is lost, VRLA cells may experience "dry-out" and lose

capacity. This can be detected by taking regular internal resistance, conductance or impedance

measurements of cells. This type of testing should be conducted on a regular basis, as an indicator

that more involved testing and maintenance may be required. Recent maintenance procedures have

been developed allowing "rehydration" of cells that have experienced dry -out, often restoring

significant amounts of the lost capacity.

VRLA types became popular on motorcycles since about 1983, because the acid electrolyte is

absorbed into the medium which separates the plates, so it cannot spill. This medium also lends

support to the plates which helps them better to withstand vibration. They are also popular in

stationary applications, such as telecommunication sites, due to their small footprint and flexibility

of installation. The electrical characteristics of VRLA batteries differ somewhat from wet -cell

lead-acid batteries, and caution should be exercised in charging and discharging them.

The VRLA battery is by far the most popular reserve power design because the electrolyte is

captive preventing it from spilling even when the case is punctured. VRLA batteries are considered

“maintenance free” & require no addition of electrolyte or water. The valve regulated lead -acid

battery is designed by development of the grid design, by modifications to the materials used in

battery manufacture and the incorporation of a sophisticated but low-cost battery management

system.

HBL now offers a VRLA tubular grid gel-type battery well tailored for applications which

require a small foot print. Gel technology affords higher operating temperatures, deeper

discharges with recharges that do not unnecessarily compromise battery service life. This battery is

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D. Cleaner Technology adopted at HBL Power Systems Ltd.

a) VRLA (Valve Regulated Lead Acid) Battery :

The Valve Regulated Lead Acid (VRLA) battery is one of many types of lead -acid batteries. In a

VRLA battery the hydrogen and oxygen produced in the cells largely recombine back into water.

In this way there is minimal leakage, though some electrolyte still escapes if the recombination

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Benefits of these batteries are as follows :

� Does not require water top-up throughout its life� No corrosive fumes and hence no special battery rooms are required� Stackable design minimizes space requirements� Designed for high integrity & long life� Application specific designs� Customized layouts for optimum space utilization� Safe-Explosion proof, leak-proof & flame-retardant materials

Consistent performance over life time� Improved aesthetics� Easy installation

Typical applications are telecommunications, switch gear, process control systems, railway signalling& communication and renewable energy.

b) Jar Formation of Battery Plates :

Battery plates undergo an electrical formation in two ways – Tank formation and Jar formation.Tank formation is the traditional process of battery plate formation before assembly. In this method ,cured pasted plates are loaded into large baths of dilute sulphuric acid and a direct current is passed toform the positive and negative plates. After formation, plates need to be thoroughly washed, driedfollowed by cutting and then assembled with separators between them into the battery boxes. Plates oflike polarity are connected by welding the plate lugs. At the end of formation, acid specific gravity (sp. gr.) goes up asper the following electrochemical reaction (based upon the inherent sulfate content in the plates andacid quantity in the tank).

Positive plate : PbSO4 + 2H2O = PbO2 + H2SO4 + 2e- + 2H+

Negative plate : PbSO4 + 2e- + 2H+ = Pb + H2SO4

After the plates are taken out from the tanks, some quantity of acid needs to be discharged (around40 lit. of acid with sp. gr. 1.080/tank) followed by dilution with water to bring the sp. gr. of the acidback to original value before the next lot of plates are loaded. Discharged acid becomes part ofeffluent.

In the modern manufacturing process this tank formation is replaced by jar formation, wherebybatteries are assembled using unformed plates followed by in-situ formation of plates in the batteryitself.

designed for microwave transmission towers, wireless/cellular huts, satellite receiver stations, fibreoptic transmission systems, radio repeater and base stations and other applications. HBL employs avacuum impregnation fill technology that eliminates air gaps, voids and inclusions prevalent inmany other gel and hybrid gel batteries. This makes a “true gel” product as opposed to a standardVRLA battery with merely a layer of gelled electrolyte “spread” across the top of the jar casing.The tubular gel series is well tolerant of deep discharge and partial state of charge (PSOC) cyclicoperations.

�

Tank formation route Jar formation route

No. of operations inplate processing

More Less

Discharge of excessacid from forming tanksafter every formationcycle

Sulphuric acid with sp. gr.1.080/circuit to be discharged everyday. (Acid content-12%)

No discharge of acid

Cleaning of tanks(approx. after every 1month)

Discharge of acid with sp. gr.1.080/circuit-once in a monthDischarge of lead oxide sludge(~176kg/circuit) from the formingtanks -once in a month

Discharge of acidic water fromwater bath (acid content < 1%) tomaintain pH above 2.

Washing of plates Both negative & positive plates needto be thoroughly washed leading togeneration of acid and lead particlescontaminated effluent.

No such washing of platesrequired.

Overall effluentgeneration (acidic &leady)

High No leady effluent generation.Acidic effluent generation is 1/4thin JF compared to that in tankformation route.

Generation of acidfumes

Significant at finishing stage fromthe large open surface

Less through use of misteliminator in the vent hole of thebatteries

Removal of acid fumes By passing through alkali scrubber By passing through alkali scrubber

Subsequent operationin the field

Acid filling followed by charging atdealer's end.

Does not require any acidhandling as well as charging atdealer's end.

ADVANTAGES OF JAR FORMATION OVER TANK FORMATION

From the customer's angle the jar formation route gives following benefit :

� batteries are available ready to use� Control in acid quality and proper charging

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In the jar formation process, batteries are filled with acid of sp. gr. adjusted in a way so that afterformation the sp. gr. goes up to the final sp. gr. required in the product. Hence no acid needs to bedischarged. Moreover, there is no requirement of plate washing. Thus, generation of acid effluent issignificantly lower than tank formation. Moreover, due to less no. of operation and thereby handling,scrap generation and leady effluent generation is also less.

From pollution point of view, the jar formation process has some significant advantage over tankformation route as listed in the table below.

Stage wise Scrap Reduction Methods

Sl. No. Section Methods for Reduction of Scrap

1 Plate shop

a) Pasting Automated paste mixing system for reduced manualhandlings for reduction of lead powder spillages.

b) Curing & Drying Usage of bigger chambers and better handling systems likefork trucks & model specific skids.

2 Cell Assembly Automated cell assembly lines for minimising processrejections

3 Formation Programmable charger cum dischargers and dataloggingsystems for minimising manual errors and improvedproduct quality.

4 Battery Assembly &Packing

Better handling systems like pallet trucks, diesel forktrucks, battery operated trucks & EOT cranes.

5 Dispatch Better handling systems like pallet trucks, diesel forktrucks, battery operated trucks & EOT cranes.

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c) Steps taken to reduce lead scrap generation :

Apart from these t raining of manpower, preventive maintenance schedules and ISO systems which

are common as a part of TQM.

d) Automatic Electrolyte Filling :

HBL Power Systems Ltd. has adopted automatic vacuum impregnation electrolyte filling technology.

In this process, the electrolyte is filled into the cells under vacuum condition and so the chance of

spillage of acid/electrolyte in the working area is reduced to a great extent.

e) Reverse Osmosis Plant in the ETP :

The industry has installed R.O. plant in its effluent treatment section. The treated water from the

R.O. plant is reused. This reduces the chance of water pollution as well as conserves the underground

water.

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E. Secondary Lead Smelting :

With the increasing demand of batteries, generation of lead scrap/waste is also increasing day by day.

The lead wastes/scraps need to be handled very carefully to protect the environment from pollution.

The best way to handle this hazardous substance is to recycle the material. Recycling is the key

component of modern waste reduction methodology. Recycling involves processing of the used

materials into new products to prevent wastage of potentially useful materials, to reduce the

consumption of fresh materials, to reduce energy usage and also to reduce environmental pollution.

About 50% of the lead used in various applications is recovered from the secondary lead smelters.

1. Brief Manufacturing Process :

Smelting is a thermal metallurgical processing operation in which the metal is separated in

fused form from non-metallic materials or other undesired metals with which it is associated.

The main steps involved in secondary lead smelting activity are smelting of the lead bearing

wastes after addition of fuel and flux, cooling and casting of molten lead into lead ingots.

Usually, charcoal is put in the furnace and it is ignited by blowing air. Then charcoal is

fed further to fill the furnace chamber. The lead scraps/wastes and charcoal are then fed

alternately at definite proportions depending upon the raw material quality. Molten lead is first

tapped after a definite time period and made into lead ingots by pouring into moulds. Usually,

lead content in battery scrap is 75-80%. In the first charge about 40-50% of lead comes out and

the slag contains the balance lead. This slag is further charged in the furnace for melting for 3-4

times for extraction of lead. Resid ual slag contains about 2% of lead and is disposed as

hazardous solid waste.

2. Sources of Pollution :

3. Pollution Control Systems:

The main source of pollution is the emission from the lead smelting furnace. In West Bengal,

all the secondary lead smelting units are small scale and use old vatti type pit furnace. Another

major pollution source is the lead bearing slag which is a hazardous waste.

The general method of arresting the dust particles in the flue gas coming out from the furnace

is to install a cyclone separator, bag filter and then a scrubber. The lead bearing solid wastes are

stored in safe and environment friendly manner and finally disposed to engineered landfill.

F. Conclusion & Way Forward :

According to a 2003 report entitled, "Getting the Lead Out," by Environmental Defense and the

Ecology Center of Ann Arbor, Mich., an estimated 2.6 million metric tons of lead can be found in

the batteries of vehicles on the road today. There is little argument that lead is extremely toxic.

Scientific studies show that long-term exposure to even tiny amounts of lead can cause brain and

kidney damage, hearing impairment, and learning problems in children. The auto industry uses

over one million metric tons of lead every year, with 90% going to conventional lead -acid vehicle

batteries. While lead recycling is a mature industry, it's impossible to rescue every car battery from

the dump. More than 40,000 metric tons of lead is lost to landfills every year.

Lead-acid battery recycling is one of the most successful recycling programs in the world. In the

United States 97% of all battery lead was recycled between 1997 and 2001. An effective pollution

control system is a necessity to prevent lead emission. Continuous improvement in battery

recycling plants and furnace designs is required to keep pace with emission standards for lead

smelters. Also, proper collection of used batteries and extraction of lead through environment -

friendly secondary lead smelting technology like use of rotary furnace/ reverberatory furnace in

place of old vatti type furnace need to be practised to minimize the scope of environmental

pollution.

In West Bengal, apart from Exide Industries Ltd., mostly lead acid batteries are manufactured in

small scale sector and these are located in clusters in some areas. Adoption of modern

technologies/automation in battery manufacturing and charging will certainly reduce the risk of

environmental pollution/degradation but it is a challenging task for the tiny scale units. ECAC may

take up a demonstration project in one such cluster of small scale lead acid battery manufacturing

units in this regard.

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Gel filling section Gel filling section

Automatic gel filling of battery Automatic gel filling of battery

Automatic gel filling section at M/s HBL, Meheboob Nagar, Hyderabad

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F. O. fired rotary furnace for lead smelting Vertical alloy making furnace(F.O. fired)

Cyclone separator connected to F.O. firedrotary furnace of lead smelting section

Bag house connected to F.O. fired rotaryfurnace of lead smelting section

Wet scrubber connected to F. O. fired meltingpot for alloy making

Wet scrubber connected to F. O. firedmelting pot for alloy making

Furnaces and APC devices of smelting and alloying section at M/s HBL, Meheboob Nagar,Hyderabad

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Battery breaking section Battery breaking section for separation oflead and plastic from used batteries

Battery breaking section

Lead strips preparation section at M/s HBL, Meheboob Nagar, Hyderabad

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Bag house for product collection of red leadsection as APC device

Cyclone separator for product collection ofred lead section

Lead sub oxide and red lead manufacturing units at M/s HBL, Mehboob Nagar, Hyderabad

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Flow Diagram of the ETP Flow Meter at the intake point

Inlet to collection tank Collection tank

Used acid gel mixture during filling withinbattery stored within vats at ETP for treatment

pH adjustment and equalization tank

Effluent Treatment Plant at M/s HBL, Meheboob Nagar, Hyderabad

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Cake preparation at filter press after lime dosingfor pH adjustment

R. O. section

R. O. section

Lead oxide paste preparation Lead oxide paste preparation

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Different sections for lead oxide pasting onto strips at M/s HBL, Meheboob Nagar,Hyderabad

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Plastic moulding division of M/s. HBL, Mehboob Nagar Plant, Hyderabad