How to produce magnesium sulfate from boric magnesium slag

During its manufacturing, borax chemical factories have to get rid of boric magnesium slag, which could be purified into magnesium sulfate heptahydrate if well used. Boric magnesium slag mainly contains MgCO3 and also contains other impurities as MgO, SiO2, Fe2O3, FeO, CaO, Al2O3, MnO, etc.

Production process:
First of all, add sulfuric into boric magnesium mud for acid splitting, then adjust PH as 1, get the filtrate after precipitation.

Secondly, continue to add boric magnesium mud in the filtrate. When the PH adjust to 5~6, add NaClO solution and boil the mixture. At this time, Al3 +, Fe3 + have been hydrolyzed and Mn2+ would be oxidized into MnO2. The sediment now contains MnO2, SiO2, Fe (OH) 3 and Al (OH) 3. By this time, impurities as Al3 +, Fe3 +, Mn2 + have been removed.

Then, continue to filter out impurities, CaSO4 · 2 h2o or CaSO4 could be removed after evaporating and concentration,.

Finally, evaporate concentrate once again. After cooling the solution, magnesium sulfate heptahydrate , Epson salt, could be filtered.