Removal of Ammonia Nitrogen from Copper-Ammonia-Thiosulfate Gold Leaching Tail Liquid by Magnesium Ammonium Phosphate Precipitation Method
Thiosulfate method is considered to be the most promising method for gold extraction to replace cyanidation,but the large amount of residual ammonia nitrogen in the gold leaching tailings has potential environmental risks and has become one of the bottlenecks in the industrialization of this method.The effect of magnesium ammonium phosphate precipitation method on the removal of ammonia nitrogen from thiosulfate gold leaching tail liquid was studied.n(Mg)∶n(N)∶n(P),pH value,time,thiosulfate radicals and copper were investigated.The effect of ion concentration on the removal performance of copper ammonia was discussed.The effects of NaOH dosage,thermal decomposition time and temperature during the thermal decomposition of magnesium ammonium phosphate and the feasibility of cyclic ammonia removal of thermal decomposition products were discussed.The results showed that at normal temperature,pH=10.n(Mg)∶n(N)∶n(P)=0.9∶1∶0.9,and the reaction time is 45 min.The ammonia nitrogen removal rate in the thiosulfate gold leaching tail liquid can reach 95.28％,and the resulting precipitation The thermal decomposition reaction of the material at 120 ℃ and n(NH4+)∶n(NaOH)=1∶2 for three hours can remove 99.80％of ammonia nitrogen,and has good cyclic ammonia removal performance.
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