| 摘要 |
The invention relates to a process for upgrading siliceous and argillaceous bauxites which contain up to 60 % mineral siliceous, argillaceous, carbonaceous impurities and which, in their natural state, cannot be exploited for the preparation of alum earth by the Bayer process. According to the invention, the process comprises the following steps : soaking the bauxite in water, up to saturation, and further on subjecting the bauxite to autogenous disintegration, primary hydraulic classification to 0.063 mm, stage grinding in mills having discharge chamber, secondary classification to 0.063 mm, ultrasonic trituration and finally eliminating, by centrifugal hydraulic classification, the fraction of 0,005 mm wherein the siliceous, argillaceous, carbonaceous impurities are concentrated. During the grinding process, the humidity enables the sonic energy transmission through capillaries and pores with good effects on the grinding productivity.
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