Zinc powder recovery gold process

Zinc powder is often used as a reducing agent in the Merrill-Crowe process to recover gold from pregnant cyanide solutions. The process involves the following steps:

1. Clarification: The pregnant cyanide solution is first clarified to remove any suspended solids or organic matter.

2. Precipitation: Zinc powder is added to the clarified solution, causing the gold to precipitate out as a solid.

3. Filtration: The solid gold is then separated from the solution by filtration.

4. Washing: The solid gold is washed with water to remove any remaining zinc powder or cyanide.

5. Smelting: The gold is then smelted to produce a doré bar, which is a semi-pure alloy of gold and silver.

The recovery efficiency of zinc powder in the process is affected by various factors such as the particle size of the zinc powder, the pH value of the solution, the temperature, and the stirring speed. Optimizing these factors can improve the recovery efficiency of gold and reduce the consumption of zinc powder.