Method of extracting chemical preservatives from treated wood

摘要

Preservatives and oil are extracted from treated wood. For this purpose, treated wood that is intended to be discarded is comminuted, the chips are impregnated with an alkaline solution until softening of the chips and modification of the chemical state of the products to be extracted. Possibly, the chips may be treated with saturated steam at a temperature between 170 DEG C. and 210 DEG C. followed by an explosive decompression giving wood fragments. This is followed by a refining operation in a crusher permitting the grinding of the wood. The result is a substantial release of the preservatives and oil from the wood chips which are at least partly disintegrated. The chemical preservatives and the oil are collected separately from the wood chips in the aqueous phases which are produced in the impregnation, steam cooking-explosive decompression and refining steps.