What are the refining methods for silver electrolysis?

One, adding acid for precipitation

The principle is that thiosulfate ions decompose into sulfur and sulfur dioxide gas in the presence of acid, and silver ions combine with sulfur to form silver sulfide precipitate. When silver sulfide is burned in a high-temperature furnace, it is decomposed into monomeric silver and sulfur dioxide gas.

Second, electrolysis

Stainless steel plate is used as a cathode and a direct current is applied to produce metallic silver at the cathode. If well controlled, the purity of silver can reach 90-98% and the recovery rate is around 90-95%.

Third, metal substitution

Substitution with reactive metals is a simple method with low purity and low recovery.

Fourth, sodium borohydride reduction

Since sodium borohydride has strong reducing properties, it can replace metallic silver in its alkaline solution. Secondary recovery method recovery rate of up to 99.9%, the recovery of silver purity of about 96%-98%.

Five, reducing sugar reduction method

In recent years, someone has developed a method to recover silver from organic reducing solution, first using tartaric acid and sucrose to prepare reducing sugar solution, and then use this reducing sugar solution to reduce the silver in the waste fixing solution. The main advantage of this method is that carbon, silicon, iron, aluminum, copper, etc. will not be mixed into the silver powder, so that the recovery of silver purity is higher (> 99%), the silver recovery rate of more than 95%.

Sixth, the reduction method of sodium dithionite

Using sodium bisulfite (Na2S2O4), you can directly reduce silver from the waste fixing solution and oxidize it to Na2S2O3. this method not only makes the silver recovery rate high and obtains high grade silver, but also improves the quality concentration of Na2S2O3, the main component of the waste fixing solution, so that the waste fixing solution can be regenerated. Our company specializes in the supply of precious metal refining and silver extraction consumables, such as crucible silver test paper filter cloth. Buy silver electrolysis equipment can also visit Zhengzhou Jinquan official website to contact