INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

Case Study #234

1. Headline: Pollution Prevention Assessment for a

Manufacturer of Starting, Lighting, and Ignition (SLI)

Batteries

2. Background:

What is EP3?

The amount of pollutants and waste generated by industrial

facilities has become an increasingly costly problem for

manufacturers and a significant stress on the

environment. Companies, therefore, are looking for ways to

reduce pollution at the source as a way of avoiding costly

treatment and reducing environmental liability and

compliance costs.

The United States Agency for International Development

(USAID) is sponsoring the Environmental Pollution

Prevention Project (EP3) to establish sustainable programs

in developing countries, transfer urban and industrial

pollution prevention expertise and information, and

support efforts to improve environmental quality. These

objectives are achieved through technical assistance to

industry and urban institutions, development and delivery

of training and outreach programs, and operation of an

information clearinghouse.

EP3's Assessment Process

EP3 pollution prevention diagnostic assessments consist of

three phases: pre-assessment, assessment, and post-

assessment. During pre-assessment, EP3 in-country

representatives determine a facility's suitability for a

pollution prevention assessment, sign memoranda of

agreement with each facility selected, and collect

preliminary data. During assessment, a team comprised of

US and in-country experts in both pollution prevention and

the facility's industrial processes gathers more detailed

information on the sources of pollution, reducing this

pollution. Finally, the team prepares a report for the

facility's management detailing its findings and

recommendations (including cost savings, implementation

costs, and payback times). During post-assessment, the EP3

in-country representative works with the facility to

implement the actions recommended in the report.

Facility Background

This facility manufactures starting, lighting, and

ignition (SLI) batteries. Most of the facility's output is

sold domestically, although about 20% is exported. The

facility operates one, two, or three 8-hour shifts

(depending upon the equipment, process, and season) and

employs 220 people. In 1993, they sold 231,000 batteries.

This assessment evaluated a facility that manufactures

lead-acid batteries used in automobiles and trucks. The

objective of the assessment was to identify actions that

would: (1) reduce the quantity of toxics, raw materials,

and energy used in the manufacturing process, thereby

reducing pollution and worker exposure, (2) demonstrate

the environmental and economic value of pollution

prevention methods to the battery industry, and (3)

improve operating efficiency and product quality.

The assessment was performed by an EP3 team comprised of

an expert in battery production and a pollution prevention

specialist.

3. Cleaner Production Principle: The assessment identified

various cleaner production applications including: process

modification, good housekeeping, new technology,

recycling, and material substitution.

4. Description of Cleaner Production Application:

Overall, the assessment identified nineteen pollution

prevention opportunities that could save over $1,521,206

(US) in the first 12 months for an investment of $522,500

(US). If implemented, these changes could reduce employee

exposure to lead dust, reduce energy and water use per

unit output, reduce the amount of lead purchased, reduce

lead-contaminated waste water, and improve product

quality.

Manufacturing Process

Facility operations can be divided into six main steps:

(1) conversion of scrap lead into cast panels, (2)

conversion of virgin lead into lead oxide powder and

paste, (3) pasting and curing of panels, (4) container

formation of batteries, (5) tank formation of batteries,

and (6) laboratory analysis and process controls. The

battery making process begins on two parallel tracks: the

facility recovers lead from used batteries that are

collected and brought to the facility, scrap lead is

recycled and then cast into grids, and virgin lead is

mechanically converted into a powdery lead oxide, which is

used to make a paste. These separate feeds merge at the

grid pasting machine where the paste is pressed into the

grids. Pasted plates are cured and then take one of two

paths to become battery elements: tank formation or

container formation. These processes convert the paste

into active material that will electrically charge and

discharge throughout the useful life of the battery. In

tank formation, this process takes place in large tanks

whereas in container formation, the cured plates are

assembled and formed in the battery case itself.

To make the lead oxide paste, lead oxide powder is mixed

with de-ionized water, sulfuric acid, and organic

expanders. One recipe makes a positive plate, while a

slightly different recipe makes a negative plate. The

pasted plates then move on a conveyor belt through a

drying oven. After pasting and drying, the plates move

into a curing chamber for about 48 hours to convert the

remaining lead into lead oxide.

In tank formation, the positive and negative plates are

immersed in tanks of low specific gravity sulfuric acid,

where electrodes pass a current through the plates. In the

positive plates, the current converts lead sulfate from

the paste into lead oxide. In the negative plates, the

reaction converts the paste into sponge lead, a very

porous, high surface area form of elemental lead.

Container formation employs the same electrochemical

process, but occurs in the plastic battery case instead of

the tank. Cured plates that are not tank formed must be

cut in half and assembled into battery elements, which are

then placed into batteries for container formation.

After tank formation, the plates go through a washing an

drying process to remove any remaining sulfuric acid.

Overall, the plate washing process accounts for over 60

percent of the factory's water contaminated with lead and

sulfuric acid.

Existing Pollution Problems

At the time of the assessment, there were a number of

pollution problems at the facility, including:

(1) waste acid from the used batteries that are cracked to

recover lead is disposed of on-site, (2) uncovered lead

slag and dust piles, (3) excessive energy used in smelting

ovens, curing rooms, and the tank formation process, and

(4) excessive wastewater generation in the grid pasting

and washing processes. In addition, over 2,500 kilograms

of lead oxide paste was spilled and fed into the smelting

process each day, using virgin lead where scrap lead would

suffice. Finally, several technological problems (e.g.,

the outdated lead oxide mill and lack of a moisture

analysis oven) increased raw materials use and adversely

affected battery quality.

Pollution Prevention Opportunities

Overall, this assessment identified nineteen pollution

prevention opportunities that could address the problems

identified and produce significant economic benefits for

the facility. If implemented, these opportunities could

save over $1,531,206 (US) in the first 12 months for an

investment of $ 522,500 (US).

The pollution prevention strategy is premised on the

belief that addressing sources of waste and pollutants

also improves the company's economic health by reducing

operating costs and improving product quality. In this

case, product quality is increased by (1) increasing the

lead oxide particle size by buying a liquid atomization

mill, (2) increasing the moisture content of the paste

recipes, (3) increasing the curing temperature, humidity,

and air circulation, (4) analyzing the moisture content of

the pasted plates on-site, at the oven, (5) monitoring the

smelting oven temperature and adjusting to the optimal

level, (6) curing larger batches of pasted plates, and (7)

utilizing cadmium sticks in the laboratory to measure cell

voltage.

The following is a lists of the opportunities for

pollution prevention recommended for the facility and

presents the environmental and product quality benefits,

implementation cost, savings, and payback time for each.

Because the quantities of pollution generated by the

facility and possible pollution prevention levels depend

on the production level of the facility, all values should

be considered in that context.

--Conversion of Scrap lead into Cast Panels--Smelting--

Options included

1. Cover slag and dust piles and clean

smelting room reduces worker exposure to lead

and lead dust. Costs $500 (US) provides

financial benefit of $3,750 (US) per year and

has a pay back period of less than two months.

2. Buy temperature monitoring instrument

to adjust oven reduces toxic emissions and slag

and reduces energy costs. Costs $1000 (US)

provides a financial benefit of $1000 (US) per

year and has a pay back period of one year.

--Casting Panels--Option included: Purchase improved

design mold which reduces waste, lowers energy use and

eliminates steps in the process. The cost is $100,000

(US). Financial benefit and payback period is

incorporated in plate cutting.

--Conversion of Virgin lead into lead oxide powder and

paste-- Options included:

1. Shovel spilled lead cylinders back

into the mechanical mill rather than smelting

ovens- conserve lead and energy. There is no

cost and the financial benefits equal $88,646

(US) per year therefore providing an immediate

payback.

2. Purchase a liquid lead automization

mill - improves efficiency and reduces emissions

of lead oxide powder. The cost is $200,000 (US)

which provides quality improvements.

3. Sell old equipment once the liquid

atomization mill is operating which recovers

some of the costs of new purchase. There is a

financial benefit of $10,000 (US) per year.

--Pasting and curing panels: Pasting-- The options

included:

1. Shovel spilled paste back into paste

hopper rather than smelting oven - which reduce

lead purchases, reduces volume of waste water,

and saves energy. There is no cost, it saves

$479,546 (US) per year with an immediate

payback.

2. Increase moisture content of the paste

- reduces scrap and extends battery life.

Improves the quality.

3. Reduce the water flow to the finishing

roller on paste machine - reduces water use and

volume of waste water. It save $2,000 (US)

year.

4. Buy a moisture analysis oven to make

better lead and to save energy. The cost is

$2,000 (US) it will provide and annual benefit

of $500 (US) per year therefor paying for itself

in two years.

--Pasting and curing Panels: Curing-- The options

identified included:

1. Install racks to cure larger batches

to save energy and extends battery life. The

$1000 cost will improve product quality.

2. Install mist sprayers, a heater, and

two fans in each cutting room improves battery

life, and therefore improves product quality.

3. Analyze the free lead content after

twelve hours of curing saves energy and extends

battery life. The financial benefits will

depend on the curing.

--Pasting and curing Panels: Cutting-- The options

identified included:

1. Eliminate the cutting process which

reduces scrap and saves lead and energy. The

cost is $100,000 with a financial benefit of

$70,956 per year and a payback period therefor

of less than 18 months.

2. Recycle drops to strap casting pot

rather than smelting oven - saves lead and

energy. The payback period is immediate as

there is no cost and financial benefits are

$20,520 (US) per year.

--Container formation: Immediately apply charge after

filling improves battery performance - there is no cost

and the payback is immediate of $36,288 per year.

--Tank formation of plates: Eliminate the process --saves

water and natural gas, reduces worker exposure to acid and

lead dust, reduces volume of waste water and improves

battery quality. The cost is $100,000 with a financial

benefit of $693,000 per year and therefore a payback

period of less than three months.

--Tank formation: Washing and drying of plates--Stop

washing all plates immediately will reduce waste water.

There is no cost and it will result in saving of $125,000

per year.

--Laboratory Analysis and Process Control: Laboratory

Analysis--Accurately measure individual battery cell

voltage assures battery quality. The cast of $500 (US)

will improve battery quality.

The total costs of these actions is $522,500 (US) and the total

financial benefits are $1,531,206 per year.

Evaluating Performance

EP3 is developing a methodology for measuring and tracking

pollution prevention performance. The approach uses simple but

critical ratios to compare data among facilities in the same

industrial sector.

This assessment identified four critical ratios, as shown in

Table 1 (below). The Assessment Team developed best industrial

performance (BIP) values for these ratios, and found that each

of this facility's current values were significantly above the

BIP values. The facility should be able to reduce its ratios

and come closer to the BIPs by implementing the pollution

prevention options listed above.

Ratio BIP

Current Ratio at

Facility

Kilograms of virgin 8.0 11.2

lead per battery unit

Kilograms of lead- 5.0 9.7

alloy feed per

battery unit

Liters of water used 50 150

per battery unit

Kilowatt-hours (kwh) 7 kwh 10.7 kwh

and cubic meters and and

(m3) of natural gas 5 m3 6.6 m3

per battery unit

Implementation Status

The facility has already implemented many of the low/no cost

recommendations, including covering recycled lead piles,

recycling dropped virgin lead into the lead oxide mill rather

than into the smelter, recycling waste paste into the hopper

rather than sending it to the smelter, and maintaining optimal

temperature and humidity in the curing room. In addition, the

facility has begun to implement several capital intensive

changes. For example, it has placed an order for boost charging

equipment ($ 100,000 US) and requested price quotes for a

liquid lead atomization mill ($ 240,000 US).

5. Economics: See above.

6. Advantages: See above.

There is an additional opportunity to prevent pollution

and conserve raw materials in the battery recycling

process. Before cracking the battery case, workers could

pour the acid into a large plastic plating tank. The acid

could be recycled (possibly through ion exchange) and

returned to the production process, replacing purchases of

high concentration acid.

7. Constraints: No information provided.

8. Contact:

EP3 Clearinghouse (UNITED STATES)

TEL: 1 (703) 351-4004

FAX: 1 (703) 351 6166

Internet: apenderg@habaco.com

9. Keywords: battery, good housekeeping, recycling, material

substitution, new technology, process modification, EP3,

lead, acid, plate, cadmium, water saving, smelting, USAID

10. Reviewer's comments: This case study was carried out in a

developing country in which EP3 has an established

programme. It was submitted to UNEP IE and edited for the

ICPIC diskette in August 1995. It has not undergone a

formal technical review.