有色金属(冶炼部分)

黔北务川一正安一道真(简称务正道)地区铝土矿资源富锂现象显著，具有较好的锂资源利用潜力。选取务正道地区代表性大型矿床瓦厂坪铝土矿开展富锂铝土矿中铝锂溶出性能研究，所取铝土矿样品Al_2O₃、SiO₂和SO₃含量分别为60.66%、10.90%和8.23%，铝硅比为5.57，属于高硫型中低铝硅比铝土矿，锂含量为337μg/g，主要是以类质同象的形式存在于绿泥石黏土矿物中。研究结果表明，原矿最适宜溶出条件为：苛性碱浓度246 g/L、溶出温度255℃、溶出时间45 min、石灰添加量12%、固液比1∶3 g/L,Al_2O₃实际溶出率为79.65%,Li实际溶出率为71.23%。采用焙烧工艺对铝土矿原矿进行脱硫活化，在原矿最适宜条件下进行溶出试验，活化后矿石中Al_2O₃实际溶出率80.93%,Li实际溶出率81.29%，整体溶出性能优于原矿，说明矿石经焙烧后，硫化物和有机物含量降低，矿石晶体结构被破坏，有效提高了矿石的溶出性能。热力学数据计算表明，Al_2O₃和Li_2O与NaOH在255℃(528 K)时反应吉布斯自由能分别为–190.05、–72.53 kJ/mol。采用收缩未反应模型进行反应动力学研究，结果表明，溶出温度在255℃时，Al_2O₃的溶出反应属于边界层传质控制，速率常数为0.003 6 min^-1;Li的溶出反应属于化学反应控制，速率常数为0.008 15 min^-1。

Lithium is recognized as a strategic critical metal, yet China's lithium supply remains heavily importdependent due to multifaceted constraints. In the Wuchuan-Zheng'an-Daozhen area(abbreviated as Wuzhengdao) of northern Guizhou Province, a pronounced lithium enrichment has been identified within bauxite deposits, exhibiting an average lithium concentration of 756 μg/g, 2.5 times higher than the national average for Chinese bauxite(306.5 μg/g). This region contains proven bauxite reserves of 700 million metric tons, with estimated prospective reserves reaching approximately 980 million metric tons. The associated lithium oxide(Li_2O) resources are quantified at 1.82 million metric tons, demonstrating considerable potential for lithium resource exploitation. This study selects the representative large-scale Wachangping bauxite deposit in the Wuzhengdao area to inveatigate the digestion performance of aluminum and lithium in lithium-rich bauxite. The bauxite sample taken has contents of Al_2O₃, SiO₂ and SO₃ of 60.66%, 10.90% and 8.23% respectively, with an Al/Si ratio of 5.57, which belongs to highsulfur type bauxite with medium and low Al/Si ratio. The lithium content is 337 μg/g. The XRD analysis shows that the main minerals are boehmite, SiO₂ and Fe_2O₃, and lithium exists in the form of isomorphism in chlorite clay minerals. The digestion experiments show that the actual digestion rates of Al_2O₃ and Li is 79.65% and 71.23% respectively under the most suitable digestion conditions for the raw ore including dissolution temperature of 255 ℃, caustic alkali concentration of 246 g/L, lime dosage of 12%, solid-liquid ratio of 1∶3 g/L, and dissolution time of 45 minutes. Under these conditions, the main phases of the digested red mud are Na_2O · Al_2O₃· SiO₂· nH_2O and Fe_2O₃, and no characteristic peak of boehmite is found. The SEM microstructural analysis reveals morphological alterations in the red mud, including internal pore formation due to mineral dissolution, indicating thorough extraction of Al_2O₃ and Li_2O. Desulfurization treatment of the raw ore was carried out by roasting method. The digestion experiment was carried out under the most suitable digestion conditions. The experimental results show that after activation, the actual digestion rate of Al_2O₃ and Li in roasted ore is 80.93% and 81.29% respectively. The overall digestion performance is better than that of the raw ore, indicating that the sulfur and organic matter contents in the ore are reduced after roasting, and the crystal structure of the ore is destroyed. Thermodynamic data calculations show that the Gibbs free energy of the reactions of Al_2O₃ and Li_2O with NaOH at 255 ℃(528 K) is –190.05 kJ/mol and –72.53 kJ/mol, respectively. The reaction kinetics was studied using the unreacted shrinking core model. The results show that at dissolution temperature of 255 ℃, the digestion reaction of Al_2O₃ is controlled by boundary layer mass transfer, with a rate constant of 0.003 6 min^-1. The digestion reaction of Li is controlled by chemical reaction, with a rate constant of 0.008 15 min^-1.