Method for recovering valuable metals and acids from stainless steel pickling waste liquid

摘要

The stainless-steel-washing waste solution of 15-20 wt.% nitric acid, 5-10 wt.% fluoric acid, 1-1.5 wt.% Cr, 0.5-1.0 wt.% Ni and 2.8-3.0 wt.% Fe is treated by step-extracting the organic phase of Cr and nitric and fluoric acid at the phase rate of A/O = 2-5 with organic solvent of 30-50 vol.% trioctylamine, 10 vol.% isodecanol and 40-60 vol.% kerosene from the waste soln., washing the organic phase with Na2CrO4 soln. at A/O = 1 to remove nitric and fluoric acid, getting Cr-concentrated water phase with NaCl soln. at A/O = 0.2, recovering Na2CrO4 4H2O from the water phase, recovering NiSO4 by the similar way.