石灰对三水铝石型铝土矿低温溶出行为的影响

研究了不同石灰添加量对3种国外三水铝石型铝土矿在145℃时溶出性能的影响规律及其作用机理.国外三水铝石型铝土矿主要由三水铝石、针铁矿、赤铁矿、高岭石和石英等组成，并含有一定的锐钛矿和一水软铝石.研究结果表明，添加石灰能够促进脱硅反应的进行，降低溶出后铝酸钠溶液中二氧化硅的质量浓度，随着石灰质量分数的增加，溶液的硅量指数逐渐提高；添加石灰降低三水铝石型铝土矿的氧化铝溶出率，其与石灰的质量分数呈线性递减关系；石灰促进脱硅产物由水合铝硅酸钠向水化石榴石转变，随着石灰质量分数的增加，溶出液中的苛碱质量浓度逐渐提高，赤泥中碱的质量分数逐渐降低.

Effect of Lime on Digestion of Gibbsitic Bauxites at Low Temperature

The effects and function mechanism of the different amount of lime additions on the digestion properties of three kinds of gibbsitic bauxites obtained from abroad were investigated at 145 °C. All the gibbsitic bauxites are comprised of gibbsite, aluminogoethite, hematite, kaolin, quartz as well as minor anatase and boehmite characterized by XRD. The results showed that the lime addition promoted the desilication reactions, which decreased the concentrations of alumina and silica of digested sodium aluminate liquor. The corresponding silica index increased gradually and the alumina digestion rates of gibbsitic bauxites decreased linearly with the increase of the mass fraction of the lime. The conversion of desilication products from sodium silicon aluminum hydrate to hydrogarnet was also promoted by the addition of lime. The concentration of caustic alkali increased and the mass fraction of the alkali in the red mud decreased gradually with the increase of the mass fraction of the lime.