INTERNATIONAL
CLEANER
PRODUCTION
INFORMATION
CLEARINGHOUSE
INTERNATIONAL
CLEANER
PRODUCTION
INFORMATION
CLEARINGHOUSE
CASE STUDY #239
1. Headline: EP3 - Pollution Prevention Assessment for an
Electroplating Facility
2. Background:
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.
Summary
This assessment evaluated an electroplating facility. The
objective of the assessment was to propose a program of
pollution prevention 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
electroplating industry, and (3) improve operating
efficiency and product quality.
The assessment was performed by an EP3 team comprised of
an expert in electroplating and a pollution prevention
specialist.
Facility Background
This facility is an electroplater that performs zinc,
nickel, brass, and chrome plating. Seventy percent of
production is comprised of brass articles. The facility
operates with 23 workers who work in a single 8-hour
shift, 300 days a year. Approximately 15 m2 of metal
surface is finished per day.
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 18 pollution prevention
opportunities at this facility. Recommendations for
pollution prevention include replacing the solvent
degreaser with an alkaline cleaner, improving process
solution monitoring, and capturing and returning 100
percent of chromium dragout to the process solution.
Manufacturing Process
Facility operations can be divided into five main steps:
(1) polishing, (2) cleaning, (3) racking, (4)
electroplating, and (5) gilding.
Parts are first polished. Polishing paste is applied to
stationary belt sanders to provide the necessary abrasion.
The parts are then polished with the sanders. Dust
generated by the polishing process is collected by vacuums
connected to each machine.
Prior to electroplating, many parts are cleaned in a vapor
degreaser that uses trichloroethylene (TCE) to remove
grease and other impurities. Parts removed from the
degreaser are dried with paper towels.
The facility electroplates many different kinds of parts.
Several parts are hung on special racks that are
constructed specifically to handle the part. Other pieces
are plated in baskets that are placed directly in the
solutions.
The electroplating line consists of washing tanks, rising
tanks, and nickel and chrome plating and recuperation
baths. A copper cyanide bath is located across from the
line and is used to plate zamak before it is plated to
nickel and chrome. All plating is manual. Times are not
exact, and there considerable variation in soaking times
among different parts and different workers.
Before gilding, parts are rinsed in special rinse baths.
They are then immersed in gilding solution for less than a
minute.
Existing Pollution Problems
At the time of the assessment, there were a number of
pollution problems including (1) polishing debris, (2) the
use of organic solvents for degreasing, (3) acid dip
contamination, (4) inefficient cyanide electroplating, (5)
unnecessary chrome and nickel waste, and (6) excessive
water use.
Pollution Prevention Opportunities
The assessment identified 18 pollution prevention opportunities
that could address the problems identified above, with
significant environmental and economic benefits to the
facility. Listed below are the recommended opportunities for
the facility, and the environmental benefits and implementation
costs for each.
Summary of Recommended Pollution Prevention Opportunities:
--Polishing--
1. Reduce time between buffing and cleaning-
Financial benefit will depend on costs of degreasing.
2. Replace polishing compound with one compatible
with aqueous alkaline cleaners. Financial benefits
will depend on the costs of degreasing.
3. Improve operator performance by purchasing
fixtures and jigs provide training. Financial
benefit will depend on the cots of degreasing.
4. Reduce compound and heel use through proper
operating practice. Immediate financial benefits
will be about $150-$300 (US) per year.
--Solvent degreasing--replace this process step with
aqueous alkaline cleaner--The costs involved are about $5000
(US) with a financial benefit of $11,134 (US) per year and
therefore a payback period of less than 6 months.
--Alkaline cleaning--
1. Eliminate cyanide use in cleaning--No
implementation costs with an immediate payback
period with $895 (US) per year.
2. Improved process control and solution
monitoring. Less than $100 (US) costs with an
immediate payback period and financial benefits
of $930 (US) per year.
--Acid dip--10% sulfuric--
1. Isolate acids for steel and brass. No
cost and improves the product quality.
2. Improved process control and solution
monitoring. No costs, immediate payback and
financial benefits of $144 (US).
--Acid dip--Depassivation of nickel: Eliminate this
process step: cleaner is adequate: Immediate payback, no
costs and financial benefit is $672 (US).
--Acid dip Mixed acid stripper--replace with solutions in
smaller tanks, and practice segregation and recovery.
Reduced treatment costs.
--Copper cyanide--Improved process control and solution
monitoring. Improved product quality and costs estimated
at less than $100 (US).
--Cyanide brass electroplating--Improved process control
and solution monitoring, results in improved quality.
--Nickel electroplating
1. Improved process control and solution
monitoring. Improved product quality with less
solution loss. Costs are estimated at less than
$100 (US).
2. Less frequent purification. Costs
have already been incurred in other options, and
the immediate benefits were estimated at $4,130
(US) to $5875 (US) per year.
--Chrome electroplating--
1. Capture and return 100% of dragout to
the process solution. Costs nothing and reduces
need for treatment.
2. Improved process control and solution
monitoring porous pot. Costs estimated at $500
to $1000 (US) with financial benefits because of
the elimination of treatment, has a payback
period of 1-2 years.
--Rinsing effectiveness--Add agitation and sprays; control
water use and reduce water use; cost of less that $100
(US) results in a benefit of at least $19,783 (US) with a
payback period of less than three months.
The total costs of implementing the opportunities is
estimated at $5,500 to $6,500 (US) with financial benefits
estimated at least $19,783 per year.
Polishing Debris. As currently performed, the polishing
process leaves considerable debris (consisting of a
mixture of polishing compound and solids from the
polishing wheel) inside the pieces. These deposits cannot
be removed by scraping or wiping.
To alleviate this problem, the facility can take several
steps. Reducing the amount of polishing compounds used
will reduce the amount of debris. Removing visible residue
will allow less debris to harden on the pieces. Reducing
the time between buffing and cleaning will also allow less
debris to harden on the pieces. Lastly, employing a
polishing compound that is compatible with alkaline
cleansers will improve the efficiency of the cleaning
process (along with recommendations outlined in the next
section).
Degreasing. The facility currently employs the chlorinated
solvent TCE to degrease parts. TCE is highly toxic and
chemically reactive, and has been linked to liver cancer
and ozone depletion. Parts can be cleaned equally well, or
better, through the use of aqueous alkaline cleaners.
Thus, the facility can greatly reduce its environmental
impact and improve product quality by implementing an
alkaline cleaning system. Further, the alkaline system
cost effective than the TCE system. A $ 5,000 investment
will yield savings (from eliminated solvent purchases) of
$ 12,000 (US) per year.
Acid Dips. In this facility's plating process, an acid dip
(usually 10 percent sulfuric acid) is used to remove any
oxides that may have developed on the brass or steel
surface. With time, copper and organic contamination
accumulates in the acid bath. If more than 300 mg/l of
copper is present in the acid dip, the bath can cause
adhesion problems for the steel substrate. Further, copper
contamination also impacts the nickel electroplating
solution. While the facility utilizes nickel depassivation
to remove the copper contamination, it is not efficient,
wasting nickel, brightener, and energy.
Separate acid dips for steel and brass substrates will
improve the quality of both the steel substrate cleaning,
and the nickel electroplating solution, and, hence, reduce
the number of rejects the facility produces. Additionally,
by employing tighter process control over the acid dips,
the facility will save $ 816 (US) a year in reduced
solution cost.
Inefficient Cyanide Electroplating. Cyanide electroplating
cannot be eliminated at this facility because the known
non-cyanide alkaline alternatives do not function well in
this application. However, improved process control and
solution monitoring could enhance product quality, and,
hence, reduce the number of rejects the facility produces.
Unnecessary Nickel and Chrome Waste. Currently, the
facility purifies the nickel bath six times per year. By
improving process control and purifying the nickel bath
only once per year, the facility should save between $
4,100 and $ 5,900 (US) a year from recovered nickel
solution.
The lost chrome solution is only valued at $ 180 (US) per
year. However, if 100 percent of this chrome could be
captured, the facility would not have to install expensive
chrome waste treatment required by the facility's
government. A porous pot purification system (priced
between $ 500 and $ 1,000 (US)) is capable of removing the
chromium from the waste water. While the expected costs of
meeting chromium discharge limits have not been
determined, they are sure to be greater than the cost of
the purification system.
Excessive Water Use. Waste water is generated in
significant volumes from the facility's rinse steps. Some
fairly simple changes can be made that will reduce water
use by 25 percent. The use of air or solution agitation
would increase the efficiency of the rinses, and reduce
the frequency of changes. Spray rinses would also be more
efficient than the current practice. Lastly, water inputs
should be installed with switches that turn off the inputs
after a set period of inactivity. For an investment of
less than $ 100, the facility should save $ 1,728 (US) a
year from reduced water usage.
5. Economics: See above.
6. Advantages: See above.
7. Constraints: See above.
8. Contacts:
EP3 Clearinghouse (UNITED STATES)
TEL: 1 (703) 351-4004
FAX: 1 (703) 351 6166
Internet: apenderg@habaco.com
9. Keywords: metal, electroplating, process modification,
good housekeeping, material substitution, new technology,
EP3, zinc, nickel, brass, chrome, trichloroethylene, TCE,
solvent, degreasing, acid, polishing, rinse, plating
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.