Thermodynamic Modeling And Simulation Of Aqueous Processes

摘要

Accurate and reliable simulation of aqueous solution chemistry is a powerful tool for engineersdealing with hydrometallurgical processes. The behavior of ions in plant solutions is often complicatedand counter-intuitive, and practicing engineers do not normally have the resources to evaluate everyproblem in the laboratory. The Mixed Solvent Electrolyte (MSE) model of OLI Systems has beenproven by the Aqueous Process Engineering and Chemistry group of the University of Toronto toperform extremely well for some hydromet systems of common interest. For example, our group hasused the model successfully to:1. Predict hematite solubility in H2SO4 systems at 130-27°C with and without Mg and compare withmodel predictions2. Study gypsum scaling potential in concentrated sulphate and mixed sulphate-chloride solutions from20 to 8°C3. Predict oxygen solubility in zinc pressure leach solutions4. Explain and quantify the free acid requirements in a laterite pressure leach5. Measure the solubility of Kieserite (MgSO4·H2O) at 65-105°C and compare with model predictionsgenerated using OLI Software’s MSE Model6. Predict the solubility of binary and ternary systems containing metal sulphates and ammoniaIn all cases we have developed our own thermodynamic database by calibrating the model onliterature and our experimental data. This was necessary since default databank of OLI does not coverelectrolytes under conditions of interest to hydrometallurgical operations. The calibration process ismade through OLI’s own regression facility, which is part of the software. The calibration processresults in a set of parameters specific to the electrolyte solution. Once the model is calibrated on simplesolutions its performance on complex industrial solutions is assessed and verified. The optimized set ofparameters then becomes part of a dedicated databank that can be used in conjunction with the coresoftware (called: engine) to simulate real process systems. It is proposed to correlate ion interactionparameters with temperature and solution composition from experimental solubility of binary andternary systems containing metal sulphates and ammonia. Calculating the model parameters makes itpossible to predict the thermodynamic properties of the systems for which data are not available in theliterature or cannot be measured experimentally. The results obtained by our group can be applied inhydrometallurgical processes.