Process for the purification of chloride-containing magnesium oxide

摘要

The invention relates to a process for the purification of a chloride-containing magnesium oxide which is produced as the primary product in the thermal cleavage of magnesium chloride and must be further purified in the course of further processing to give pure magnesium oxide or synthetic sintered magnesite. The aim of the invention is to improve the economics, in particular the thermal balance, of the production of magnesium oxide from magnesium chloride. The object of the invention is to develop a process which enables intermediates with much lower water-content to be obtained in the process of washing out impure magnesium oxide with water. According to the invention, this object is achieved in that the washing process including the filtration is carried out in such a manner that a low contact time between MgO and water results, which although it is sufficient to wash out the soluble impurities, does not convert the primarily readily filterable magnesium oxide, which binds little water, into the less readily filterable magnesium hydroxide, which binds considerably more water. In the process according to the invention, the hydration occurs only after the filtration, the water required for the hydration being removed from the water adhering to the filter cake. The invention can be used in the production of pure magnesium oxide.