NYS Governor's Awards for Pollution Prevention - C.H. Thompson Company
C.H. Thompson Company Inc., Binghamton
The C. H. Thompson Company, located in Binghamton, New York, was established in 1924 and is a 4-to-5 million dollar annual sales metal finishing firm specializing in mil-spec finishing. Its three divisions -- anodizing, painting, and screen-printing -- employ nearly 100 people.
The anodizing division processes chemical conversion coatings. Historically, chemical conversion coatings use chromates as a constituent element and release potassium ferricyanide as a by-product. C. H. Thompson has successfully researched and installed an environmentally acceptable substitute coating that eliminates the use of chromate while meeting the Department of Defense specifications for finishing.
Methodologies and Procedures
C. H. Thompson Company conducted a literature and market search to identify a non-chromate chemical conversion coating that was researched at the U.S. Air Force Research Laboratory in Brooks Air Force Base and the US Army Research Laboratory in Aberdeen Proving Ground, Maryland.
The company constructed a rigid metal, poly-vinyl lined 12 ft x 7.5 ft x 3 ft tank and installed it over a spill containment area that holds 16,818 pounds of process solution. Batch strengths of the potassium permanganate (KMn04) product are titrated daily and the solutions are brought to process temperatures of 140 degrees Fahrenheit. KMn04 oxidizes both iron and manganese to convert the ferrous (2+) substrate into the ferric (3+) state and 2+ manganese into the 4+ state. It then reduces these to insoluble oxides that are removed by a 5 micron Serfilco filtration system. Oxidation time ranges from 5 to 10 minutes when the process solutions are kept in the pH range of 7 to 8.
The finished parts are golden brown with the oxidation ranging from dark goldish brown (10 to 15 minutes) to medium golden brown (6 to 10 minutes). Parts are rinsed in de-ionized water and then subsequently coated electrostatically by powder coating that eliminates the use of ozone depleting solvents. Through substitution, C. H. Thompson has displaced nearly 67,273 pounds annually of process solutions containing hazardous materials.
Waste discharge of the spent process solution to Binghamton's POTW is welcomed since KMn04 is used by nearly every major municipality in the United States as a means to oxidize metals, phenols, and other inorganic contaminants from its waste streams. It is also widely used to control the odor emissions from hydrogen sulfide gasses generated by waste treatment.
- Manufacturing and disposal costs are less than with traditional chemicals.
- Waste streams of hazardous discharges are eliminated from this process.
- Multiple positive environmental usages of the waste stream.
Any comments or questions?
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