METHOD FOR PROCESSING LEATHER INDUSTRY WASTES INTO FIRE-PROOF MATERIAL Russian patent published in 1994 - IPC

FIELD: leather industry. SUBSTANCE: chrome tannage wastes are introduced in reaction medium in three steps - first 100 mass parts of the wastes are added to a sulfuric acid solution containing 10-14 mass parts of acid and 89-90 mass parts of water (sulfuric acid density 1,84 g/cm³). The mixture is stirred while boiling for 25-30 min, and wastes are added gradually for 15-20 min - 100 mass parts. The mixture is boiled again for 20-30 min, and wastes are gradually added (125-150 mass parts). The mixture is boiled for 3-4 h, then the mixture is supplemented with alum (potash or ammonium) - 5-7% of the whole mass. The mixture is stirred for 10-15 min, then dried to withdraw water. EFFECT: higher product quality. 1 tbl