采用硝酸浸出失效催化剂提取其中金属银,研究了失效催化剂粒度、硝酸用量、浸出温度、浸出时间和洗涤次数等因素对银浸出率的影响.结果表明,失效催化剂粒度对银浸出率影响显著,增加洗涤次数有利于提高银的浸出率.通过实验,确定了合理的工艺参数为:硝酸用量为失效催化剂质量的70％、浸出温度65℃、浸出时间3h、催化剂粒度为0.125 ～0.18 mm、搅拌洗涤3次.在此条件下,银的浸出率为99.52％,浸出渣含银0.072％.综合实验结果表明,从失效催化剂到海绵银产品,银的直收率达到99.27％.%Spent catalyst was leached by nitric acid to extract metallic silver from it. The effects of the particle size of spent catalyst, the dosage of nitric acid, leaching temperature, leaching time and washing times on the leaching rate of silver were investigated. The results showed that the particle size of spent catalyst has great effect on the leaching rate of silver which would also be improved by increasing washing times. Based on experiments, technological parameters are reasonably determined as follows; the dosage of nitric acid was 70% of the quality of spent catalyst, the leaching temperature was set at 65 ℃, leaching time was 3 h, the particle size was 0.125 ~0.18 mm, the washing times were 3. Under these conditions, the leaching rate of silver was 99.52% and the content of silver in the leaching residues was 0.072%. The comprehensive experiment showed that spent catalyst can be transferred to sponge silver products with this process with direct recovery rate of silver reaching 99.27%.
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