The dissolution study of a South African magnesium-based material from different sources using a pH-stat

Abstract

One of the main steps in the wet flue gas desulphurization (WFGD) process is the dissolution of either magnesite or limestone. Evaluating the magnesite dissolution rate is vital for the design and efficient operation of wet FGD plants. A study on the dissolution of magnesite from different sources in South Africa is presented in this work. The effect of reaction temperature (303.15-343.15K), solid-to-liquid ratio (0.5-2.5g/200 ml), particle size (25-125μm), pH (4-6) and HCl concentration (0.5-2.5 mol/l) on the dissolution rate was studied. It was found out that the dissolution reaction follows a shrinking-core model with the chemical reaction control as the rate-controlling step. The dissolution rate increased with an increase in concentration and reaction temperature and with a decrease in particle size and solid-to-liquid ratio. The activation energy of this dissolution process was found to be 45.685 kJ/mol.

Keywords

• Desulphurization
• Dissolution
• Ammonium compounds
• pH-Stat