亚硫酸钠分银与氨浸分银工业实验

Industrial experiments of silver extraction by sodium sulfite and ammonia leaching

在湿法处理铜阳极泥过程中,分别采用亚硫酸钠-甲醛还原法和氨浸-水合肼还原法处理氯化分金渣。通过工业试验,研究了影响银回收的主要因素,并分析了这两种方法的优劣势。结果表明：在亚硫酸钠分银-甲醛还原中,最佳浸出条件为,亚硫酸钠用量为理论值的1.3倍,室温30℃,pH值为9.2,时间4h,银浸出率可达97.69%;甲醛最佳还原条件为,其用量m（甲醛）∶m（银）=1∶2.5,pH值为9.2,时间4h,温度40℃~50℃,银还原率可达96.83%。在氨浸分银-水合肼还原中,最佳浸出条件为,体系氨浓度8%~10%,温度30℃,时间4h,银的浸出率96.11%;水合肼还原,其用量为理论值的2倍,60℃下反应0.5h,银的还原率达99%以上。

Major factors of sodium sulfite-formaldehyde and ammonia leaching-hydrazine hydrate reduction methods in dealing with chlorinated gold residue were studied by the industrial trials.Furthermore,the advantages and disadvantages of the two methods were analyzed.The experimental results showed that the optimum operating conditions for the sulfite-formaldehyde reduction method： the dosage of sodium sulfite was 1.3 times of the theoretical value,the pH was 9.2,the temperature was 30℃,and the leaching rate of silver was 97.69%;the optimum operating conditions for the formaldehyde： the mass of formaldehyde was 0.4 times of the silver,the temperature was 40℃~50℃,the pH was 9.2,and the recovery of the silver was 96.83%.the best operating conditions for ammonia leaching-hydrazine hydrate reduction method： the optimum concentration of ammonia was 8%~10%,the temperature was 30℃,the leaching rate of the silver was 96.11%;the optimal reduction condition using hydrazine hydrate： the dosage of hydrazine hydrate was 2 times of the theoretical value,temperature was 60℃,the time of reaction was 0.5h,and the reduction rate of the silver was above 99%.