Pollution Prevention and Control Technologies
for Plating Operations
Section 2 - General Waste Reduction Practices
2.3 GOOD OPERATING PRACTICES
2.3.3 Chemical Purchasing, Storage, Usage, and Handling
Proper purchasing, storage, usage, and handling of chemicals increases
the percentage of raw materials that reach their intended process
without spills, leaks or other types of losses that could result
in waste generation. Some basic guidelines for good operating
practices include (ref. 303):
- Standardization of materials, i.e., using the minimum number
of materials in all operations. Many times the decision to use
one material over another is based on operator preference, rather
than on a technical or economic requirement. Written specifications
can improve purchasing and reduce waste (PS 257).
- Avoid over-purchase of materials.
- Avoid collecting free samples of process chemicals from vendors.
Only accept amounts needed for testing purposes.
- Utilize a dedicated/protected storage area.
- Space containers in storage areas to facilitate inspection.
- Label all containers.
- Stack containers according to manufacturers' instructions
to prevent cracking and tearing from improper weight distribution.
- Separate incompatible materials in storage such as cyanides
- Raise containers off the floor in the storage area to inhibit
corrosion from ÒsweatingÓ concrete.
- Establish written procedures for process (tank) formulation
- Use specifically assigned personnel to formulate baths and
make tank additions.
- Perform routine bath analyses and maintain bath analyses logs
and tank formulation/addition logs.
- Use process baths to the maximum extent possible (do not employ
a dump schedule).
- Remove zinc anodes from the baths when they are idle to prevent
a buildup of metal in the baths.
- Implement multiple use of certain materials (e.g., soak cleaner
is reused as an electrocleaner by PS 068).
- Implement statistical process control (SPC) to improve the
efficiency of chemical use (PS 257).
Survey questions that relate to chemical usage, handling and storage
include questions 4, 5, 6, 7, 8, 9, and 10 (Exhibit 2-6). The
responses to several of these questions were previously discussed
in Section 2.3.3. The response to question 5 indicated that 273
shops (or 85.8%) use specifically assigned personnel for chemical
additions and the response to question 8 indicated that 229 shops
(or 72.0%) have written procedures for bath make-up and chemical
additions. These two pollution prevention options received particularly
high average success ratings. The response to question 9 indicates
that 234 shops (or 73.6%) use process baths to the maximum extent
possible rather than employ a dump schedule and the response to
question 10 indicates that 78 shops (or 24.5% of all shops or
approximately one-half of shops performing cadmium and/or zinc
plating) remove cadmium or zinc anodes from baths when they are
idle. The latter practice prevents a buildup of dissolved metal
in the bath, particularly with zinc plating.
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