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.degree. 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.