METHOD OF PREPARING TITANIUM HARDENER FROM TITANIUM-CONTAINING RAW MATERIAL FOR HARDENING WITH ADMIXTURES AND METHOD OF MANUFACTURING LEATHER Russian patent published in 1997 - IPC

FIELD: leather industry. SUBSTANCE: titanium-containing raw material containing components harmful for hardening process is subjected to preliminary nitric acid treatment under boiling at solids to liquid ratio 1:(2-6) to precipitate titanium. Precipitate is treated with sulfuric acid to produce titanyl sulfate sulfuric acid solution with 50-300 g/cu.dm free sulfuric acid. To this solution, ammonium sulfate is added in two steps with aging for 0.5- 2.5 h between the two additions, the first step being completed with beginning of ammonium titanyl sulfate precipitation and completion of the second step being on achieving concentration of excessive ammonium sulfate in solution 150-500 g/cu.dm. The thus obtained hardener is used when manufacturing leather with bath pH value increased to 3.7-4.4 after titanium hardening by adding acid-soluble sodium-potassium aluminosilicate in amount 8-25% relative to ammonium titanyl sulfate taken for hardening. Leather intermediate product, prior to be finally hardened with synthetic hardeners, is neutralized to pH 4-5. Raising bath pH is advantageously performed for 2-10 h at 25-30 C and neutralization of intermediate product is performed by agency of acid-soluble sodium-potassium aluminosilicate in amount 1.7-4.7% based on offal weight. Quality standardized titanium hardener is prepared from raw material containing hardening-harmful components owing to their more complete separation and synthesis of coarse-crystalline hardener. EFFECT: improved hardening procedure.