Hebei Messi Biology Co., Ltd. stated that after adding a certain amount of sulfuric acid to the MgSO4 turbid liquid released from the bottom of the ammonia evaporation tower, most of the Ca2+ is filtered out in the form of CaSO4 precipitation. The small amount of sulfates such as iron and manganese remaining in the filtered mother liquor are precipitated by adding specific auxiliary materials and then filtered to obtain a pure magnesium sulfate solution. Pure magnesium sulfate and ammonium carbonate liquid are added to the reactor and double decomposition reaction is carried out under certain conditions. The reacted materials enter the solid-liquid separator and are separated while being washed with water. The separated mother liquor containing (NH4)2SO4 is sent to the ammonia evaporation tower for recycling; the separated solid phase magnesium carbonate is hydrolyzed into ultrafine materials with pure water, and then separated by a centrifuge. The separated wastewater is recycled for the preparation of pure water. The separated solid phase is dried and sent to the roasting furnace for calcination. The calcined product is high-purity magnesium oxide.
The same set of equipment can also be used to produce high-value-added products such as light magnesium oxide, heavy magnesium oxide, and highly active magnesium oxide by adjusting process parameters. The technology of producing high-purity magnesium oxide by ammonium salt circulation method is the first in China. It is a green technology and solves two core technical problems: the selection and proportion of auxiliary materials and the process conditions of crystallization.
In future industrial production, it is necessary to select advanced equipment for each chemical unit operation, optimize the process, and realize process automation. The calcination process is also an important part of this technology, and advanced electric furnace operation should be selected. There is an amplification effect in the process from pilot to industrial production implementation, and more detailed work needs to be done. This is a problem worthy of attention of owners, technical know-how, and designers.