PURPOSE: To make it possible to reduce transportation costs, costs, and reduce amount of treatment of insoluble residue by a method wherein ore containing alumina in which particles of specific ratio are crushed to specific value or less is dispersed in a solution having specific pH value or more, which dispersion is subjected to magnetic separation to remove magnetic substances.
CONSTITUTION: For removing magnetic substances from ore containing alumina, ore containing alumina in which 90wt.% of the whole particles are crushed to a size of 50μm or less is dispersed in a solution of pH 9 or more, which solution is subjected to magnetic separation under conditions of magnetic field strength 1-10 kilogauss to remove magnetic substances. If the ore containing alumina, e.g. bauxite ore, is crushed, magnetic simple substances constituting the ore, such as hematite, goethite, and nonmagnetic simple substances, such as alumina, titania, silica, are separated, which are placed in a solution of pH 9 or more, whereby the particles are prevented from attaching to one another or from being aggregated. If magnetic separation is applied, yield of bauxite after the separation is improved and alumina in the bauxite can be enriched.
KASAI SHIGETERU
NIBU MITSUO
