Chemicals for use in industry; industrial chemicals based on magnesium, magnesium oxide, burnt dolomite, dolomite; industrial chemicals for metallurgical processes based on magnesium, magnesium oxide, burnt dolomite and dolomite; magnesium-based preparations, namely, magnesium oxides, magnesium hydroxide and magnesium carbonate for use in manufacture of industrial chemicals in the field of metallurgy, foundry, glass and chemistry; industrial chemicals for the production of refractory products