Dear Alireza Mirhosseini-Jalalabadi

Zinc metal is commonly used in gold cementation because it has a higher reactivity than gold, making it an effective reducing agent. In the process of gold extraction from cyanide solutions, zinc displaces gold from the solution through a redox reaction, where zinc is oxidized, and gold is reduced and precipitated out as a solid metal. This method, known as the Merrill-Crowe process, is preferred because zinc is relatively inexpensive, widely available, and can efficiently precipitate gold even in low concentrations, making it a cost-effective choice for large-scale gold recovery operations.

I hope this helps.

Hello. Thank you for your explanation