| 摘要 |
Waste red mud (Y) is subjected to from 100 to 200 hours lasting reaction with a leaching agent, which agent consists of an inorganic H2SO4 acid or a mixture of inorganic H2SO4, HNO3 acids, KNO3 alkaline salt, earth micro-organisms metabolic products selected from the group containing Deuteromycetes and water in a weight ratio 10 : 3 : 14 : 72, a pH value lower than 1, at continuous mixing or static mixing during 2 weeks at room temperature. The solid state thus formed is separated by filtration (2) and after drying (3) thereof gypsum is obtained (A). The leaching process product is subjected to crystallisation (4) resulting into a formation of crystalline phase which after filtration (5) and drying is separated and alum (B) is obtained. The filtrate (7), as a result of crystallization, is converted into an amorphous phase which, by drying (8) and calcinating (9) at 600 DEG C is transformed into a crystalline substance containing prevailingly hematite. The red pigment (C) is obtainable after milling said crystalline substance into desirable particles.
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