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CLEAN PRODUCTION IN ELECTROPLATING |
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THE COMPANY
The ARI Metallurgical Facility, located at the city of Rosario,
Province of Santa Fe, Argentina, started out in the metal surface finishing business 19 years ago.
This facility currently has 7 employees in a 6,000 sq. ft. plant.
Its annual production is 800 tons of plated, blued, phosphatized
and plasticized items, with an annual billing of approximately
U.S.$180,000.
PROGRAM
FOR POLLUTION PREVENTION AND CLEANER PRODUCTION
In
March of 1996, the provincial government issued a law regulating
maximum concentrations of pollutants allowed in industrial effluents
discharged into sewers, and non-compliance with this law is
penalized by cutting off sewer utility access to companies.
There used to be regulations that allowed for more tolerant
values, but they were not being observed by either companies
or authorities. The deadline set by this law for suspending
discharges into sewers expired on December 5, 1998.
In late 1998, critical parameter
values at the ARI Metallurgical Facility (chromium and cyanide) exceeded
the limits established by legislation by 15 times. This situation
was shared by the rest of the industries established in the
province. For this reason, these companies got together to form
the Business Chamber for Metal Surface Treatment (CETSUM), and
they arranged for both private technical assistance and assistance
from domestic and international organizations. The result was
the creation of a program focused on pollution prevention and
clean production. ARI was the first
plant to perform the pilot for testing the program’s efficiency.
In November of 1999 a technical cooperation and joint working agreement
was signed with the German Technical Cooperation Agency(GTZ) and from then on, this institution has been making valuable contributions.
THE
TRADITIONAL PROCESS
Degreasing by dipping is the first
stage that items go though, with the exception of items that
are going to be plasticized. After this process, which in some
cases is electrolytic, pickling is done with hydrochloric acid
(HCl) and this is neutralized with sodium carbonate (Na2CO3).
A)
Electrolytic Electroplating.There are two kinds of electrolytic electroplating:
- Items in bulk: first, electroplating is performed in drums then followed
by rinsing.
- Large sized items: Electroplating is done in two still dips and the items
are then hung on special hooks followed by rinsing.
items are finished off with blue
or gold passivations by dipping in
chromate solutions, followed by rinsing. There were five rotating
cyanide baths plus one rotating acid bath, one still cyanide
bath and one still acid bath for this operation.
B)
Bluing.This is performed by dipping the items in a vat
containing a mix of oxidizing salts and alkalis at the proper
temperature, then the items are rinsed and coated with oil for
protection.
C)
Phosphatizing. Items to be phosphatized are subjected to the action of chemicals
at the temperature of boiling water, rinsed and spin dried.
D)
Plasticizing. Materials to be treated are subjected to heating in a natural gas
oven, and once they get to a certain temperature they are submerged
in a fluid bed of polyethylene powder which sticks to the metal
surface. When needed, finishing is completed by scorching with
a torch.
After these processes were performed, no treatment was being performed
on effluents other than pH regulation and partial sedimentation
of suspended solids.
ECOEFFICIENCY
STRATEGY APPLIED
For starting off the program, an analysis was made of processes,
which detected sources of pollution, and waste in both raw material
and labor due to unnecessary operations, plus flow conflicts
due to design flaws in equipment and operations layouts.
Staff was then provided training and awareness with a main focus
on the seriousness of the situation and the need to comply with
regulations in order to maintain this source of employment.
The first specific action taken was to replace the alkali-cyanide
electroplating baths with chloride
acids, in an effort to eliminate the need for performing cyanide
treatments. Only one cyanide bath has remained in operation
for jobs with alloys that are very seldom performed, in a confined
section with special safety measures.
Then the layout for processes and equipment was redesigned, with
the idea of preventing labor losses due to unnecessary movements
and bringing in process solutions. These solutions included:
- Draining processes
- Changes in rinses
- Segregation of effluents with chromates
The available labor manpower of the company was used in all these
operations, plus assets that were either mostly being used already
or were in inventory, so investment was minimal.
RESULTS
After replacing the alkali-cyanide electroplating baths with chloride acids, it became
possible to eliminate cyanide treatments. Electrical consumption
decreased notably due to their greater efficiency. In addition
to this, the chemicals required for preparing and maintaining
these baths are also cheaper.
Redesign of process and equipment layouts provided for recovery
of resources by preventing labor losses and making improvements
in processes.
The first of these improvements was made in draining processes which
provided a significant decrease in the carryover of treatment
solutions to downstream processes. The second improvement involved
a change in rinses for decreasing water usage, by bringing in
reactive, recoverable rinses which are kept leakproof and at
counterflow, which enabled consumption decreases that did not
affect product quality. Lastly, effluents containing chromates
were segregated for non-continuous treatment, which insured
the elimination of chrome in effluents at low operating cost.
In addition to attaining compliance with legislation, significant
financial benefits were also achieved by making these changes.
The table following shows a summary of results by comparing the
status before (1998) and after these improvements (1999). To
avoid any distortions due to fluctuations in the amount of work
being done, results are referenced directly to production. In
other words, index values were obtained for each month before
calculating savings percentages according to the following formula.
Monthly expense = Amount expended
Tons produced
Financial
Results
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Resource
Optimized
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Practices Used
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Investment
made
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Annual Financial Benefit (U.S.$)
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Percentage
Savings
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Time for it to Pay for Itself
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Chemicals
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Change in technology, recovery, optimization.
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$3.600 (1)
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$ 7.700
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14 % ($)
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170 days (2)
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Electric Power
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Change in technology, shorter circuits, less water pumping.
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$600.-
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17.000kWh*
$ 2.000.-
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33 % ($)
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109 days
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Labor
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Flow and layout improvements, elimination of unnecessary operations.
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$2.500
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$ 5.000
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9 % ($)
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182 days
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Water Usage
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Rationalization and change in use and kind of rinses.
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$850
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$3.000
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84 % (v)
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103 days
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Decrease in cyanide sludges
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Change in technology, use of acid baths.
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Included in (1)
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$600
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87 % (v)
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Included in (2)
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Total
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$ 7.550
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$ 18.300
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*Savings expressed
in kWh, and money equivalent thereof at local cost.
($) Percentage
of money savings.
(v) Percentage
of volume savings.
In summary, with
an investment of U.S.$ 7.550, an annual savings of U.S.$18.300
was achieved, which enables cost recovery in 150 days. Because
this is a continuous improvement process, recent reports are
showing that these above mentioned improvements are being surpassed.
CONCLUSION
The result from
putting the Cleaner Production Program in place surpassed expectations
by a wide margin, because the company has internalized training
and has kept on with a continuous improvement process. The ARI
Metallurgical Facility, motivated by the financial savings the
Program has provided, is continuing on with plans for progressing
even further in the use of clean technologies. In addition,
these results have been spreading throughout the region, because
of the 60 existing companies in the electroplating
business in the province, 23 are currently in the Cleaner Production
Program and the number continues to rise.
This program,
which started as an industry initiative in response to legal
pressure, is currently affiliated with the PLEDS (Business Leadership
Program for Sustainable Development) and it is proof that leadership
is built on specific deeds and not on words.
OUTLOOK
The outlook for
the Program is that the number of companies joining will continue
to grow. In times of financial recession, it is hard even for
large companies to survive, and harder still for small companies,
which are faced with numerous threats to their continued presence
in the market. Ecoefficiency is one of the tools that can enable
them to stay in business and continue to grow.
GLOSSARY
Chromates:
Hexavalent chrome compounds present in process effluents frompassivation,
with features that are hazardous to human health and the environment.
Electrolytic
Galvanizing: Provision of a coating of zinc on a metal surface
through the use of electrolysis.
Electroplating:
An electrolytic process in which a coating of metal or metal
alloys becomes deposited on an electrically conductive surface.
Passivation:
A conversion process that bonds a coating of chromates
on top of zinc plating, providing it with additional protection
against corrosive agents.
Vat:
An open metal vessel with an anti-corrosive coating, or made
of APM polyethylene, used in electroplating processes.
CONTACT
Ing.
Claudio Colombo
Colón 2064
2000 Rosario,
Santa Fe
Argentina
Phone: (54) 341-4827058
Fax: (54) 341-465
0275
e-mail: :colombo@cablenet.com.ar
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