The article presents the results of a mathematical model development for the process of gold leaching from gold-containing ores and concentrates. A mathematical model has been developed by analyzing the chemistry of reactions and mass transfer processes. On the base of a kinetic extraction model and a hydrodynamic complete mixing model a mathematical model of thiosulfate leaching process in various types batch reactors, complete mixing flow process vessels and complete mixing reactor columns with different numbers of vessels in a column has been developed. The effect of the number of reactors in a column has been investigated and optimal segmentation conditions have been found. Based on the investigation of the process using the mathematical model a control system structure has been designed to provide maximum conversion at the exit area of a reactor column.
Modern metallurgy pays more attention to chemical processes safety of staff and nature environment. One of the most hazardous branches in metallurgy is gold ores cyanidation. Researches on possibility to avoid cyanide leaching are carrying out during last thirty years. Cyanide competitors are thiosulphate and thiourea solvers. Within international cooperation between National Mineral Resources University and Lappeenranta University of Technology researches are devoted to tiosulphate leaching improvement. Main efforts are forwarded on process chemistry, however mass transfer processes of heterogenic systems are important as well. Therefore their optimization is planned to achieve by means of computer modeling based on particle image velocimetry.
A kinetic gold leaching model, based on the well-known shrinking core model, is presented in this work. The model considers the effects of internal diffusion, surface reaction and unreacted amount of gold in the concentrate particle during leaching. The model parameters are estimated by minimization of mismatching between experimental data and results of numerical computation of kinetic model made by using ReactOp software.
Computer based modeling is increasingly strengthening its position in equipment designing, especially unique meeting particular needs of production line or certain plant of metallurgy. There are several reasons for that such as economic benefits, wide range of geometry available to be built and possibility of comprehensive study on materials reliability as well as virtual model testing in working regime. One of the most applied and therefore permanently developed program packages for fluid behavior modeling is Fluent product of ANSYS company. The package is being used for creation first physical and in future chemical model which will be capable to describe and predict process and reactions behavior of high quality taking place in gold leaching gas-liquid reactor with thiosulphate using.