| 摘要 |
<p>Dissolution of goethite-contg. bauxite by the Bayer method comprises treating the Bauxite with an aluminate lye contg. 80-300 g. Na2O (caustic) per litre with addition of 2-6 wt. % of Ca cpds. calculated as CaO, opt. in the presence of 1-20g NaCl/l. and/or 1-7g. SO42-/l. at 180-300 degrees C, is improved in that the bauxite dissolution is carried out in the presence of 0.3-2.0 wt. % of Mn2+ (pref. in the form of an oxide-hydroxide manganese ore, or Mn-impurities in the bauxite) and/or Fe2+ (pref. in the form of FeSO4.7 H2O, or an iron ore, or Fe2+ impurities in the Bauxite, or partly reduced red mud) and/or Co2+ and/or Mg2+ (pref. in the form of calcined magnesite and/or dolomite). The dissolution is pref. carried out in a tubular reactor. The goethite contained in the bauxite is converted to haematite more rapidly and at lower temps. than in the known process; the sepn. of the red mud is facilitated; the loss of caustic soda is reduced.</p> |
