Hydrometallurgy

MAIN STEPS OF THE HYDROMETALLURGICAL PROCESS


1. Leaching
In the first step, metals are dissolved from ores or other raw materials using acidic or alkaline solutions. Common solvents include sulfuric acid, nitric acid, and cyanide solutions. The technology used depends on the metal being extracted:

• Cyanide leaching: mainly used for gold and silver extraction.
• Acid leaching: applied for copper, nickel, and other precious metals.
• Ammonia leaching: suitable for extracting certain metals, such as copper.

2. Purification and Separation
Before metal extraction, impurities must be removed from the solution. This can be done by:

• Precipitation, where the desired metal is chemically precipitated.
• Solvent extraction, which uses organic solvents to separate the metals.
• Ion exchange technology, especially effective for rare earth and precious metals.

3.Metal Recovery and Refining
Metals are recovered from the purified solution by various techniques:

• Electrolysis: extraction using electric current, resulting in very pure metal.
• Cementation: precipitation using metal powder or metal plates.
• Chemical precipitation using reagents such as hydrogen peroxide or other reducing agents.

4.Waste Management and Environmental Protection
By-products and wastes generated during hydrometallurgical processes must be carefully handled to minimize environmental impact. Some of the used solutions can be recycled, while solid wastes are neutralized or stored in specialized containers.