| 摘要 |
<p>Magnesite ores with a grain size of 0.2-60 mm are concd. by (a) opt. subjecting the ore to preliminary gravity sepn. (when large amts of low-density gangue are present); (b) calcining the ore at (i) 600-1100 degrees C, when the only contaminants are SiO2-based minerals, (II)680 degrees C, when dolomite is present, to decarbonate the magnesite but not the CaCO3, or (iii) 1100 degrees C, when calcite is present, to effect total decarbonation; (c) in case (iii), immersing the calcined ore in H2O contg. 0.9 g/l of a surfactant to convert the free CaO into Ca(OH)2, which is leached out; and (d) subjecting the product to flotation in a dense medium to isolate the lighter concentrate. The produce is suitable for use in the prodn. of refractory materials. Steps (b) and (c) allow precise adjustment of the density difference between the magnetic and the gangue.</p> |
