| 摘要 |
<p>A method of treating minerals containing at least one naturally magnetic or magnetizable substance comprises treating said minerals with a NaOH solution having a NaOH concentration higher than 35% by wt. and a temperature not less than 110 DEG C., seeding the solution with ferrous ions or divalent metal ions of an ionic radius similar to that of the ferrous ion, and separating the naturally magnetic or magnetizable metallic oxides, or causing them to settle, by applying a magnetic field. The term "minerals" includes not only ores mined directly out of the ground and materials that are partly or completely the residue of physical and chemical treatment of such ores, but also coke. The process is especially applicable to the treatment of bauxites or Al ores containing Fe and/or Mn. Mg++, Zn++, Mn++, Cu++, Ni++ and Co++ are exemplified as divalent metal ions having an ionic radius similar to the Fe++ ion. The magnetic field can be continuous or periodic, and may be provided by electro- or permanent magnets or by rotating fields in the sodium hydroxide solution. Surface active agents may be added to the liquids used in the method. KOH solution may be added to the NaOH solution used in the first step of the process. In the treatment of the "red muds" obtained in the Bayer process, after magnetic separation of the oxides, the oxides may be washed, the washings being returned to the residual sodium hydroxide solution, which may be processed conventionally to yield a solution containing NaOH and NaAlO2, which may be recycled for attacking the bauxite.</p> |
