Computer Simulation for Extraction Process of Gold from Thiourea Solution

A computer simulation for the continuous multistage countercurrent extraction process of gold from a thiourea leach solution was carried out by using the batch extraction and stripping data. The thiourea/hydrochloric acid/TBP system and the thiourea/sulphuric acid/TOA system were investigated for this simulation. Gold concentration in each extraction and stripping stage, and the final outlet concentration of gold and the recovery were estimated by the simulation under various conditions of stage number and phase ratio. The simulation by expressing extraction and stripping isotherms as a mathematical function and taking the function in a computer program is considered to be a superior method to estimate the extraction and stripping behaviors in each stage in a steady state. It is recognized that 8 stage extraction with the phase ratio of 5-6 and 8 stage stripping with the phase ratio of 0.3-0.4 gives 90% recovery and 15 times concentration in the case of the thiourea/hydrochloric acid/TBP system. The thiourea/sulphuric acid/TOA system is inferior to the thiourea/hydrochloric acid/TBP system in the viewpoint of the overall recovery and concentration of Au