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Process for detoxification of CCA-treated wood
Process for detoxification of CCA-treated wood
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机译：CCA处理过的木材的排毒方法
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摘要
A chemical process for detoxifying spent CCA (copper, chrome, arsenic)—treated wood, from which CCA and detoxified wood are recovered for recycling comprising the steps of (a) treating CCA-treated wood in the presence of a liquefying reagent such as an organic solvent at 100–250° C. with or without ferrous ions to form liquefied CCA-treated wood (b) adding water or an aqueous solution of an organic solvent to the liquefied CCA-treated wood with stirring to obtain an aqueous solution of liquefied CCA-treated wood (c) adding complexing or precipitating agents, such as phosphoric acid or calcium hydroxide to the aqueous solution of step (b) thereby precipitating insoluble heavy metal complexes or precipitates and forming a solution of detoxified CCA-treated wood (d) separating said heavy metal complexes or precipitates from the solution of detoxified liquefied CCA-treated wood and (e) isolating chromated copper arsenate from said heavy metal complex or precipitate.;Further, the solvent may be removed from the solution of detoxified CCA-treated wood of step (d) to obtain concentrated liquefied detoxified CCA-treated wood. This concentrated material may be used as a phenolic or polyurethane intermediate.;Additionally, by adding a concentrated inorganic acid, such as sulfuric acid, nitric acid or phosphoric acid, to the complex or precipitated solids of step (d), chromated copper arsenate can be recovered for use in manufacturing additional CCA-treated wood.
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