Process for producing alumina
    3.
    发明授权
    Process for producing alumina 失效
    氧化铝生产工艺

    公开(公告)号:US5122349A

    公开(公告)日:1992-06-16

    申请号:US530085

    申请日:1990-05-29

    IPC分类号: C01F7/06

    CPC分类号: C01F7/062 C01F7/0666

    摘要: An improvement in the process for extracting alumina from gibbsitic bauxites, wherein the basic, known process comprises mixing the bauxites with a sodium hydroxide-sodium aluminate digestion liquor, digesting the bauxites at a temperature in the range of 100.degree.-180.degree. C., diluting the resulting slurry, separating the red mud therefrom, precipitating alumina hydrate by cooling and agitation of the sodium aluminate liquor, and calcining the alumina hydrate precipitate to obtain alumina, wherein the improvement is characterized by so controlling the process that, in the liquid phase of the slurry leaving the digestion reactor, the reactive hydroxide ion concentration is maintained below 6 g/l, and preferably between 0 and 2 g/l, where the reactive hydroxide ion concentration is defined by the following formula: ##EQU1## where: C.sub.Al.sbsb.2 O.sub.3,gi.sup.eq is the equilibrium solubility of Al.sub.2 O.sub.3 for gibbsite, in g/l.C.sub.Al.sbsb.2 O.sub.3 is the actual concentration of Al.sub.2 O.sub.3, in g/l andC.sub.SiO.sbsb.2 is the actual concentration of SiO.sub.2, in g/l.Desirably, control of the process is maintained by regulating the ratio of bauxite to digestion liquor.

    摘要翻译: 碱性已知方法包括将铝土矿与氢氧化钠 - 铝酸钠消化液混合,在100-180℃的温度下消化铝土矿, 稀释所得浆料,从中分离红泥,通过冷却和搅拌铝酸钠液体沉淀氧化铝水合物,并煅烧氧化铝水合物沉淀物以获得氧化铝,其中改进的特征在于控制在液相中 离开消解反应器的浆料中,反应性氢氧根离子浓度保持在6g / l以下,优选在0至2g / l之间,其中活性氢氧根离子浓度由下式定义:其中:CAl 2 O 3 gieq是三水铝矿的Al2O3平衡溶解度,单位为g / l。 CAl2O3是Al2O3的实际浓度,g / l,CSiO2是SiO2的实际浓度,单位为g / l。 理想地,通过调节铝土矿与消化液的比例来保持该方法的控制。