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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3 h、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%。
Silver nitrate leaching catalyst was used to extract the metallic silver. The effects of catalyst particle size, nitric acid dosage, leaching temperature, leaching time and washing times on the silver leaching rate were studied. The results show that the particle size of the spent catalyst has a significant effect on the leaching rate of silver. Increasing the number of times of washing helps to improve the leaching rate of silver. Through experiments, the reasonable process parameters were determined as follows: the amount of nitric acid is 70% of the mass of the catalyst, the leaching temperature is 65 ℃, the leaching time is 3 h, the catalyst particle size is 0.125-0.18 mm and the mixture is stirred and washed three times. Under these conditions, the leaching rate of silver is 99.52% and the leaching residue contains 0.072% silver. The comprehensive experimental results show that the direct yield of silver reaches 99.27% from the spent catalyst to the sponge silver product.