Method of extracting pure silver

Silver is a precious metal with limited reserves and output. Recycling can save resources and increase economic income. Silver-containing wastes mainly come from film processing plants, computer phototypesetting, photo studios and hospital radiology departments. There are many ways to extract silver from waste fixing solution, such as electrolysis, ion exchange and air flotation. These methods have their own characteristics and shortcomings. At present, China's urban recycling work is well done, and the majority of grass-roots units do not need expensive equipment because of the scattered waste liquid, so the recycling work is poor. This requires simple equipment and simple technology to solve. Here are several simple and easy ways to withdraw silver.

1. organic matter reduction method: the prepared reducing solution directly reacts with silver-containing waste liquid, which can reduce grayish brown crude silver and simply smelt pure silver.

2. High-temperature reduction method (conventional method): easily-purchased chemical raw materials react with silver-containing waste liquid to precipitate black silver compounds, and then react with reducing agent at high temperature in charcoal fire (liquid phase treatment is enough, the method is simple, and the silver quality is high) to obtain silver with purity above 95%, and silver with purity of 99.5% is obtained by secondary smelting.

3. Replacement method: adding a chemical raw material to the silver-containing waste liquid can directly precipitate silver mud and obtain pure silver after simple treatment.

4. Waste membrane treatment and silver extraction process (incineration, acid treatment, alkali treatment, biological enzyme method for detailed process flow and matters needing attention).

5. Simple test method for silver content in waste liquid.

6. Silver recovery method of silver-containing electronic equipment.

7, black and white fixer and color fixer recycling matters needing attention.

8. The simplest and most practical film processing method.