磷酸废砷渣复合碱浸液的砷回收工艺

Arsenic Recovery Technology from Compound Alkali Leaching Solution of Phosphoric Acid Waste Arsenic Residue

摘要: 在NaOH和NaClO作复合浸出剂从磷酸废砷渣中浸出砷的基础上，以SO₂对氧化脱硫后的浸出液进行砷还原，然后进行冷冻结晶得HAsO₂晶体，实现砷的回收。研究表明，还原反应的适宜条件为：温度30℃，还原时间3 h，溶液pH0，反应液五价砷浓度为33.10 g/L，此时HAsO₂一次结晶率达53.85%；HAsO₂的冷冻结晶适宜条件是：温度−15℃，溶液pH0，冷冻时间3 h，此条件下砷结晶率为90.22%。

Abstract: On the basis of leaching arsenic from waste arsenic residue of phosphoric acid with NaOH and NaClO as compound leaching agents, SO₂ was used to reduce arsenic in the leaching solution af-ter oxidative desulfurization, and then the HAsO₂ crystal was obtained by freezing crystallization to realize arsenic recovery. The results showed that the optimum conditions for reduction reac-tion were: temperature 30˚C, reduction time 3 h, solution pH0, concentration of pentavalent ar-senic in reaction solution 33.10 g/L, and the primary crystallization rate of HAsO₂ reaching 53.85%. The suitable conditions for freezing crystallization of HAsO₂ were: temperature −15˚C, solution pH0, freezing time 3 h, under which the primary crystallization rate of HAsO₂ was 90.22%.