Highly Efficient Recovery of Au(I) from Gold Leaching Solution Using Sodium Dimethyldithiocarbamate

Area of Science:

• Hydrometallurgy
• Materials Science
• Environmental Chemistry

Background:

• Thiosulfate is a sustainable, non-toxic alternative to cyanide for gold leaching.
• Limited gold ion recovery from thiosulfate solutions hinders its widespread application.

Purpose of the Study:

• To demonstrate the feasibility of gold recovery using sodium dimethyldithiocarbamate (SDD) precipitation.
• To evaluate the recyclability of ammonia and lixiviant after gold recovery.
• To elucidate the mechanism of gold recovery by SDD.

Main Methods:

• Gold ion recovery via SDD precipitation from thiosulfate leaching solutions.
• Analysis of gold recovery efficiency and capacity.
• Assessment of ammonia and thiosulfate recycling on ore leaching rates.
• Density functional theory (DFT) calculations to validate interaction mechanisms.

Main Results:

• SDD effectively precipitates gold ions, achieving near-complete recovery within 1 minute.
• A high gold recovery capacity of 7.99 kg/t was achieved.
• Recycling ammonia and thiosulfate did not significantly impact the gold ore leaching rate (remained at 81%).
• Ligand exchange between SDD⁻ and Au[(S₂O₃)₂]³⁻ was identified as the recovery mechanism.

Conclusions:

• SDD precipitation is a viable, efficient, and environmentally friendly method for gold recovery from thiosulfate solutions.
• The process allows for the recycling of key leaching agents, improving sustainability.
• SDD precipitation shows significant potential for large-scale industrial application in gold recovery.