应用酸法提取废胶片中银的研究

废胶片中银的回收方法有多种，常见有酸法、碱法、电解法、沉淀分解法等。试验研究了从胶片中提取银的工艺，即用硝酸对废胶片在一定条件下浸取，浸取液经沉淀，水洗去杂，熔炼，铸锭，得到银锭。试验结果表明，在HNO3体积分数为10％（1．590mol／L），浸取温度为50℃，浸取时间为9min，浸取次数为3次的条件下，浸取效果最好；浸取液中的银采用碳酸钠还原回收，粗银粉配以熔剂高温熔炼可得到纯度达99．5％的银。该工艺合理，还原速度快，反应完全，原料成本低，操作方便，适用于实验室或工业生产。

Study on silver recovery from waste photosensitive film with nitric acid

There are a variety of methods for silver recovery from waste photosensitive film, such as acid method, alkali method, electrolysis, sedimentation decomposition and so on. A new method of silver nitrate preparation from waste photosensitive materials has been studied. First, the extraction solution of nitric acid for photosensitive materials is precipitated and washed. And then the solution is roasted and cast into sliver bullion. The experiment results show that the best extracting effects can be achieved when the concentration of HNO3 is 1. 590 mol/L, the temperature is 50 ℃, the extracting time is 9 min and the operating times are 3. The silver in extracting solution can be recovered by sodium carbonate and purified to 99.5 % of purity by melting at high temperature. It is a fast, easy, complete-reaction and low-cost method to recover silver from waste photosensitive materials and it can be applied in laboratory and industry production.