Gold Leaching from an Oxide Ore Using Thiocyanate as a Lixiviant: Process Optimization and Kinetics

Area of Science:

• * Extractive Metallurgy
• * Chemical Engineering
• * Environmental Science

Background:

• * Cyanide leaching poses significant environmental and health risks.
• * Thiocyanate (SCN-) presents a less toxic alternative for gold extraction.
• * Optimization of thiocyanate leaching parameters is crucial for industrial application.

Purpose of the Study:

• * To optimize gold recovery from oxide ore using thiocyanate leaching.
• * To investigate the influence of thiocyanate concentration, Fe3+ concentration, and pulp density.
• * To determine the optimal leaching conditions and kinetics.

Main Methods:

• * Response surface methodology was employed to optimize leaching parameters.
• * Key parameters investigated: initial thiocyanate concentration (10-500 mM), initial Fe3+ concentration (10-500 mM), and pulp density (10-50% w/v).
• * Kinetic study under optimum conditions to identify the rate-controlling mechanism.

Main Results:

• * Maximum gold recovery of 96% was achieved under specific conditions: 500 mM thiocyanate, 100 mM Fe3+, and 50% pulp density.
• * Optimal conditions were maintained at 25 °C and pH 2 for 24 hours.
• * Kinetic analysis indicated the shrinking core model, with diffusion as the rate-limiting step.

Conclusions:

• * Thiocyanate leaching is a viable and effective method for gold extraction from oxide ores.
• * Optimized conditions significantly enhance gold recovery efficiency.
• * The study provides valuable insights for developing safer and more sustainable gold extraction processes.