特殊钢酸洗废液回收--扩散渗析-石灰石法

本方法用扩散渗析法回收特殊钢酸洗废液中的酸,用石灰石法处理渗析残液回收镍、钴,在国内外资料中尚未见这方面的报道.该方法的特点是工艺简单,操作方便,不产生二次污染,有经济效益.

RECOVERY OF SPENT PICKLING SOLUTION OF SPECIAL STEELS BY DIFFUSION DIALYSIS-LIMESTONE METHOD

Acids can be separated from metallic salts in spent liquor and recovered in the form of free acids using diffusion dialysis by applying concentration difference and selective permeability of the dialyzer. By making use of solubility product principle and pH difference during hydroxide precipitate formation for heavy metal ions in spent liquor, residual dialyzate is simply and effectively treated by employing limestone powder or reducing furnace slag as neutralizing precipitant, to recover nickel and cobalt. The method herein presented goes in steps as follows. Bulk of free acids is recovered by passing spent liquor through diffusion dialyzator and reused in pickling operation. Then residual dialyzate is neutralized to pH 4-5 under normal temperature using limestone powder or reducing furnace slag. The filtrate obtained after precipitation of iron and chromium is neutralized to pH 8-9 by using NaOH or Na₂CO₃ to recover nickel and cobalt in the or of hydroxides or carbonates. The liquor to be discharged is a colorless, transparent solution of weak basicity.