In the pulp, the gold grains are selectively wetted by mercury to form amalgam (or mercury paste). The amalgam contains AuHg₂, Au₂Hg, and Au₃Hg，which are separated from other metallic minerals and gangue. This gold separation method is called amalgamation.

Amalgamation is an old and widely used method which still plays an important role in the gold production industry. Due to gold is free state in ore, some gold grains in all kinds of gold bearing ore can be recovered by amalgamation. In general, the recovery rate of gold ores treated with amalgamations is about 60%-80%, and the gold content in tailings is still very high. For this reason, except in placer deposits, amalgamation rarely becomes a separate operation, it often forms a combined process with other methods to improve the recovery rate of gold. It has been proved that gold loss in tailings can be significantly reduced when a part of gold is taken out in advance by amalgamation in the gold separation process.

Amalgamation process is simple, easy to operate and low cost. However, due to the toxicity of mercury, it is harmful to operators and the environment, thus affecting the application of amalgamation. Therefore, the application of this method has been severely restricted.