Chloride solution leaching of platinum from Indonesia gold ore artisanal mining

Platinum has been growing in economic importance in recent years. Limited occurrence of large scale deposits and ever-increasing demand have encouraged the utilization of deposits with low grade ore. Efficient yet small scale applicable method of extraction is needed to utilize those deposits. Chloride solution based leaching facilitates excellent condition for platinum dissolution by significantly reducing its reduction potential and through formation of stable aquochlorocomplexes. This paper reports optimization of chloride solution based platinum leaching from Indonesian artisanal ore under variation of lixiviant concentration, leaching time, pulp ratio, and leaching temperature. The Taguchi method was used to optimize the process. Hydrochloric acid was chosen as primary source of chloride ion and H₂O₂ were added as oxidizer. Parameters were arranged in L-9 orthogonal arrays and optimized through signal to noise ratio (S/N Ratio). Analysis of variance was utilized to identify the influence of each parameters to overall leaching process. The suggested optimized condition was: HCl concentration = 12 M, leaching time = 6 h, pulp ratio = 0.1, and temperature = 75 °C. It has been identified that time was the most influential parameter.