Leaching magnesium oxide in boron mud by water with pressurized CO2

Abstract

In the process of leaching magnesium oxide by water containing CO2, the obtained concentration is normally only 5g/L to 12g/L. To obtain concentrated magnesic leaching liquor from boron mud, pressurized dissolution processes were investigated under various CO2 pressures from 1MPa to 5MPa, as well as ratios of solid to liquid, stirring speeds and leaching temperatures, which significantly influenced the leaching of magnesium oxide. And the concentration of MgO in the solution was achieved as high as 26.63g/L with MgO leaching efficiency of 38.80% under the condition of CO2 pressure 5MPa, solid/liquid ratio 0.18, stirring speed 500rpm, leaching temperature 50°C, and leaching time 1.5h, meanwhile, the impurity concentrations of CaO, B, Fe, Al and Si were 0.16g/L, 0.11g/L, 0.23g/L, 0.01g/L and 0.06g/L, respectively. The magnesium oxide leaching method by pressurized carbonated water is applicable for treating with other materials rich in magnesium hydrate or magnesium oxide, such as calcined magnesite, dolomite and boron mud by CO2-soda process.