我国煤矸石中蕴藏大量镓资源,镓的伴生回收利用逐渐成为研究热点。伴生镓经酸法提取与富镓母液电解造液制备金属镓,镓综合回收率仅60%。随着氧化镓需求量增加,研究富镓母液直接水解沉淀制备氧化镓新工艺,通过缩减金属镓制备流程,显著提高镓产品综合回收率。然而富镓母液中镓离子浓度低、且与硫酸根共同作用水解转化机制尚不明确,为实现低浓度硫酸镓母液中氧化镓的高效制备,开展水解过程工艺和转化机理研究。通过正交试验考察硫酸体系下镓水解过程的反应温度、反应时间、搅拌转速、体系pH、初始镓浓度等因素对镓沉淀率和水解产物的影响,结合理论计算不同pH下镓的羟基配离子形态变化,明确低浓度硫酸镓溶液水解过程镓的转化机理,进一步通过单因素试验优化得到最优镓水解参数,水解产物经过煅烧制备得到氧化镓。结果表明,镓水解过程影响因素排序依次为体系pH、反应时间、初始镓浓度、搅拌速率、反应温度。硫酸体系不同沉淀pH下镓羟基配离子形态转变与沉淀物相对应规律为pH<3.5时,溶液中Ga3+和Ga(OH)2+占据主要优势,在硫酸根与镓离子的亲和作用下沉淀物相为镓明矾石;3.5<pH<6.5时,溶液中镓离子多形态共存,沉淀物相为无定形氢氧化镓;pH>6.5时,溶液中以Ga(OH)-4为主,沉淀物相由无定形氢氧化镓氧化缩合为羟基氧化镓。根据正交和单因素试验优化得到硫酸镓溶液沉淀工艺参数为pH=5.0、初始镓质量浓度1000mg/L、反应时间20min、搅拌速率150r/min、反应温度20~25℃,镓回收率达99.5%以上,沉淀物相为无定形氢氧化镓。

become a research focus. Gallium metal was prepared by acid extraction of associated gallium and electrolysis of Ga-rich mother liquor,and the overall recovery of gallium was only 60%. With the increasing demand for gallium oxide, a new process for preparing gallium oxideby direct hydrolysis and precipitation of gallium-rich mother liquor was studied to reduce the preparation process of gallium metal and improve the comprehensive recovery rate of gallium products. However, the concentration of gallium ion in Ga-rich mother liquor is low, andthe mechanism of hydrolysis and conversion by interaction with sulfate is not clear. In order to achieve efficient preparation of gallium oxidein low concentration Ga-sulfate mother liquor, the hydrolysis process and conversion mechanism were studied. The effects of reaction temperature, reaction time, stirring speed, pH of the system, initial gallium concentration and other factors on gallium precipitation rate andhydrolyzed products during hydrolysis of gallium in sulfuric acid system were investigated by orthogonal test. The morphologic changesof gallium hydroxy-coordination ions at different pH values were calculated by theoretical calculation, and the conversion mechanismof gallium during hydrolysis of gallium sulfate solution with low concentration was determined. The optimal gallium hydrolysis parameterswere obtained by single factor test, and gallium oxide was prepared by calcination. The results show that the influencing factors of galliumhydrolysis are pH, reaction time, initial gallium concentration, stirring rate and reaction temperature. When pH < 3. 5, Ga andGa(OH) in the solution are dominant, and the precipitate phase is gallium alingite under the affinity between sulfate and gallium ion.When 3.5<pH<6.5, gallium ions in solution coexist in many forms, and the precipitate phase is amorphous gallium hydroxide. When pH>6.5, Ga(OH) is the main content in the solution, and the precipitate phase is oxidized from amorphous gallium hydroxide to hydroxyl gallium oxide. According to orthogonal and single factor experiments, the precipitation parameters of gallium sulfate solution are optimized as pH 5.0, initial gallium concentration 1 000 mg/ L, reaction time 20 min, stirring rate 150 r/ min, reaction temperature 20-25 ℃ . The recovery rate of gallium is over 99.5%, and the precipitate phase is amorphous gallium hydroxide.

0 引言

1 试验

   1.1 试验样品

   1.2 试验过程

2 结果与讨论

   2.1 正交试验

   2.2 不同物相沉淀产物合成机理

   2.3 不同因素对镓沉淀过程的影响

   2.4 氧化镓材料制备及表征

3 结论