Electrolytic refining of gold is based on crude gold plate (with silver not exceeding 20%) as anode, pure gold plate as cathode, gold chlorinated complex aqueous solution and free hydrochloric acid as electrolyte, and electrolytically pure gold is obtained by electrolysis ( 99.99%).
The scale of electrolytic refining gold is generally small. The electrolytic cell uses a hard polyester plastic tank or an acid-resistant porcelain tank. The composition of the gold electrolysis mechanism can be expressed as follows:

Cathode electrolyte anode

(pure gold plate) â–¡ HAuCl ₄ , HCl, H ₂ O â–¡ (crude gold plate)

During electrolysis, the components of the electrolyte can be ionized as follows:

HAuCl ₄ ═ H ⁺ +AuCl ^-

AuCl4 ^- ═ Au ³⁺ +4Cl ^-

AuCl ₃ ^- ═ Au ³⁺ +3Cl ^-

HCl ═ H ⁺ +Cl ^-

H ₂ O ═ H ⁺ +OH ^-

According to the order of metal activity and the order of metal ion reduction, under the action of direct current, the gold on the anode loses electrons and dissolves in the solution:

Au-3e ═ Au ³⁺

Thus, the gold ions on the cathode get electrons and are reduced to metal, ie

Au ³⁺ +3e ═ Au↓

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