Leaching kinetics of gold mine tailings: the removal of manganese and iron by sodium carbonate

South Africa is a mineral-rich country with numerous metals and minerals such as gold, copper, and platinum group metals which are exploited to a significant extent. In this study the leaching of heavy metals from gold tailings was studied using sodium carbonate using gold tailings from Sibanye gold. The effect of the key leaching parameters were studied: solvent concentration, temperature, leaching time and the kinetic models were used. Leaching is a hydrometallurgical process where metals are extracted by chemical dissolution, leaving behind a residue of inert minerals originally present as well as insoluble decomposition products of the reacted mineral. The effect of concentration and temperature was tested and it was found that highest Fe extracted (39%) was at 0.5 M and for Mn (46.3%) was at 0.25 M, both at 25 ºC. It was also found that an increase in metal extraction depends on leaching time. The data obtained was modelled to determine whether the kinetic model follows the chemical controlled process or controlled diffusion process and it was found that the controlled diffusion model best fits the kinetic model at all temperatures.