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在冲洗电影片、X 光片、照像胶卷和像纸的过程中,未经感光的溴化银溶解在定影液里。回收这部份白银,通常的方法是电解法和沉淀法。前者是把两个电极插入废液里,进行电解,在阴极的不锈钢板上得到纯银。后者是把硫化钠等加入废液中,通过化学反应而得到沉淀银。此外采用离子交换法和金属置换法也可以有效地回收白银。从废定影液中回收白银,对废液中的其他药物也可综合利用,以减少污染,有利于环境保护,其工艺简单,不需要增加多少设备。因从矿石中提取一吨白银一般要花三十几万元,而从废定影液中回收一吨白银则只需要一万元左右。
Unprocessed silver bromide dissolves in the fixing solution during processing of films, radiographs, photogravure and image paper. Recycling this part of the silver, the usual method is electrolysis and precipitation. The former is the two electrodes into the waste, for electrolysis, in the cathode of stainless steel to get pure silver. The latter is to add sodium sulfide and other waste liquid, through the chemical reaction and silver precipitation. In addition, the use of ion exchange and metal replacement method can be effectively recycled silver. Recovering silver from waste fixer can also make full use of other drugs in waste liquid to reduce pollution and facilitate environmental protection. The process is simple and requires no additional equipment. Because of extracting one ton of silver from the ore generally takes three hundred thousand yuan, but from the waste fixing liquid to retrieve a ton of silver is only about 10,000 yuan.