Modeling the PVA-coated dolomite floatability in acidic media

The dolomite dissolution in an acidic medium generates CO2 gas. The utilization of such phenomenon for dolomite separation from phosphate is limited by using a surface-active agent that can keep such gas adhered to the particle surface. Among several tested polymers and surfactants Polyvinyl Alcohol (PVA) polymer showed promising results in forming stable bubbles of CO2 gas at the dolomite surface. The dolomite dissolution kinetics, in a sulfuric acid, was studied in terms of PVA coating and particle size under constant conditions of temperature and acid concentration. Based on the kinetic data, a dissolution mechanism was proposed. The suggested mechanism depends mainly on the availability of the acid to react with the dolomite particle. Thus, the reaction products play a crucial role either by preventing the acid diffusion or hiding the reactant sites. In addition, a mathematical model, representing the proposed mechanism, was developed to predict the time needed to float different particle sizes.