METHOD FOR DECHROMING CHROMED SCRAP LEATHER AND AGRICULTURAL UTILIZING ITS PROTEIN CONTENT AND REUTILIZING THE CHROMED SLUDGE

摘要

Chromium is removed from chromium tanned leather-waste enabling sepd. proteins to be used in agriculture and to reuse chromium from residual chromium sludges. Covered or open leather waste is boiled respectively with 2.0 and 0.5 M sodium or potassium hydroxide. The boiled mixt. is filtered, the filtrate contains sepd. proteins, free even from traces of chromium. Depending whether potassium or sodium hydroxide is used the protein extract finds application in animal fodder or in plant growing. Alkali pretreated protein extracts are neutralised by hydrochloric or sulphuric acid to required pH values. Chromium sludge retained in filters is reintroduced into the tannings process or is dewatered and dried for storage