In the metallurgical industry, it is used as a binder for refractory and furnace wall, and as a raw material for smelting metal magnesium. In the construction industry, the hard magnesia cement made of magnesium chloride and magnesia can be used to make artificial stone. In the chemical industry, it is the raw material for manufacturing various magnesium salts. In agriculture, cotton defoliating agent is manufactured. The food industry makes tofu coagulant.