Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group ib metal
Patent
1993-06-22
1995-05-16
Bos, Steven
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group ib metal
423 87, 423 53, 210913, C01G 300, C01G 2800, C01G 3700
Patent
active
054158478
ABSTRACT:
A chemical process for treating pit waste contaminated with chromated copper arsenate (i.e. CCA). CCA is recovered for recycling, and remaining solids are decontaminated for safe disposal. Pit wastes are pulverized and reacted with concentrate sulfuric or phosphoric acid. Wood particles are partially decomposed and approximately 60% to 70% of the CCA is leached out. The acid-treated mixture is centrifuged or filtered to separate liquids from solids. Liquids are recycled for reuse in the CCA process. CCA-bearing solids enter a heated digester equipped with an air or water cooled condenser. Concentrated nitric and sulfuric acids are inputted into the digester and the ratio of nitric acid to sulfuric acid to solids is approximately six to two to one by volume. Nitric acid completely oxidizes all organic matter in the solids. Sulfuric acid serves as a dehydrating agent and liquid media for CCA. The initial oxidation is carried out at a temperature greater than 70.degree. C. and less than 100.degree. C. In the final stage of oxidation nitric acid is reacted and passed off as lower nitrogen oxides between 100.degree. C. and 110.degree. C. Recovered nitric acid may be recycled to the instant process.
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Windandy, J. E., "Precipitation of CCA Solution for Waste Disposal," The Int. J. Wood Preserv., 3(2), 1983, pp. 83-88.
Abstract from Ei Compendex Plus (.TM.) #01598472 EI Monthy No: E18412139916 E. I Yearly No. EI84139170 Winandy Publication "Precipitation of CCA Solutions for Waste Disposal" 1984.
Bos Steven
Carver Stephen D.
Gem, Inc.
Keisling Trent C.
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