How much do you know about the classification of silver paste recycling technology?

1: A new technology of electro-stripping silver. The Institute of Material Recovery has designed its own electro-stripping silver equipment, with graphite plate as cathode, stainless steel drum as anode and many fine holes on the drum. Sodium citrate and sodium sulfite are electrolytes, and the silver-plated part enters from the head end of the drum and is sent out from the tail end of the drum. The silver on the surface of the plated part enters the electrolyte, and the substrate of the plated part is intact and can be returned for re-electroplating. The recovery rate of silver is 97-98%, the purity of silver powder is 99.9%, and the silver powder is recovered.

2. Recycling of waste silver-zinc batteries. The waste silver-zinc battery contains 52.55% silver and 42.7% zinc. Zinc is the negative electrode and silver oxide is the positive electrode, which is coated on the skeleton of copper mesh gold jewelry. The materials are recovered by dipping zinc and copper in dilute sulfuric acid respectively, and the silver powder is directly melted into ingots. When copper is leached with dilute sulfuric acid, oxidant is added, zinc-containing solution is concentrated and crystallized to generate zinc sulfate, and copper-containing solution is concentrated and crystallized to generate copper sulfate. Zinc recovery rate >; The recovery rate of silver is 98%, and the purity of silver ingot is >: 99%.

3. Recovering Silver from Waste Film Kunming Precious Metals Research Institute used dilute sulfuric acid solution to elute the silver-containing emulsion layer on color film, heated chloride salt to precipitate silver halide, chlorinated and dried or washed with organic solvent to remove organic matter, suspended in alkaline medium and reduced by sugar solid to obtain pure silver. The purity of silver is 99.9% and the direct yield is 98%. This law has been patented. The Institute of Material Recycling (formerly the Institute of Material Recycling of the Ministry of Internal Trade) used sodium thiosulfate solution to dissolve the silver halide on the waste film. During the dissolution process, an inhibitor was added to prevent the gelatin on the film from dissolving. The silver in the solution is recovered by electrolysis, and the substrate is recycled. Silver leaching rate >; The recovery rate is 98% and the purity of silver is 99.9%. This method has been applied to industrial production, and Hongda Precious Metals specializes in recovering silver powder and silver paste.

4. Recover the silver paste photosensitive material from the waste fixing solution after exposure, development and fixing. About 70-80% of the silver in the black and white film enters the fixing solution, and almost all the silver in the color film enters the fixing solution. The recovery of silver from waste fixing solution has been paid great attention to at home and abroad, and a lot of research work has been done. The recovery methods used include ion precipitation, electrolysis, metal replacement, drug reduction and ion exchange. The advantage of electrolysis is that the fixing solution after silver extraction can be returned for fixing.