Abstract: Brown corundum soot is a common secondary resource. Its main components are Si, Al, K, and secondary components include Ga, Fe, Mn, Ca, Mg, etc., which have a high recycling value. The demand for gallium metal has been increasing year by year, and the market price has shown substantial growth recently. Hence, research on the recovery of gallium from brown corundum soot is of great significance. In this work, an optimum process of sodium salt roasting followed by acid leaching was determined to extract gallium from the brown corundum soot by comparing the conventional acid leaching, conventional alkali leaching, and sodium salt roasting-leaching experiments. Effects of additive types, roasting temperature, and adding amounts of additives on the recovery of gallium were studied, and at the same time, the leaching behaviors of the three main impurity elements of Si, Al, and K in the process of gallium extraction were explored. The results showed that the recovery of gallium was only about 10% when using the conventional acid leaching to treat the brown corundum soot, while the recovery could reach 71.24% when using direct alkaline leaching at 90℃ for 3 h. After roasting, the leaching percentage of gallium was much higher than that of direct acid leaching and direct alkaline leaching. The gallium recovery of sodium carbonate roasting was higher than that of sodium chloride roasting. The leaching method of the roasted sample had a significant effect on the leaching efficiency of gallium. The order from high to low was acid leaching>alkaline leaching>>water leaching. The best gallium extraction route was found to be sodium carbonate roasting-acid leaching. The roasting temperature and the added amount of sodium carbonate remarkably affected the recovery of gallium and the recovery could go as high as 98.38% when the operational parameters were kept at a roasting temperature of 850℃, the mass ratio of sodium carbonate to soot being 1.0, roasting time of 2 h, leaching with concentration 25vol% sulfuric acid at 80℃ for 3 h, Meanwhile, the leaching rate of impurity Si was 0.31%, but as for Al and K they were both high, which brings difficulties to the subsequent purification of gallium solution and the separation of gallium.

Key words: gallium, brown corundum dust, process of roasting-leaching, impurity of Si

摘要： 棕刚玉烟灰作为一种常见的二次资源，其主要成分为Si, Al和K；次要成分包括Ga, Fe, Mn, Ca和Mg等，具有很高的回收价值。镓金属需求量逐年攀升，市场价格近年来呈现大幅增长，研究如何从棕刚玉烟灰中回收镓这一方向具有重要意义。通过对棕刚玉烟灰进行常规酸浸、常规碱浸以及钠盐焙烧后浸出试验，确定较佳的棕刚玉烟灰中提镓工艺为钠盐焙烧-酸浸。研究了添加剂种类、焙烧温度、添加剂添加量对镓浸出率的影响，同时探究了提镓过程中三种主要杂质元素Si, Al, K的溶出行为。结果表明，采用常规酸浸时镓的浸出率仅约10%，采用直接碱浸于90℃下浸出3 h，其浸出率可达71.24%。通过焙烧处理后，镓的浸出率远高于直接酸浸和直接碱浸。碳酸钠焙烧时的镓浸出率高于氯化钠焙烧。焙烧样品的浸出方式对镓的浸出率影响显著，由高到低的顺序为酸浸>碱浸>>水浸，最佳的提镓路线为碳酸钠焙烧-酸浸，且焙烧温度和碳酸钠添加量对镓的提取率影响显著，在焙烧温度为850℃，碳酸钠与烟灰质量比为1.0，焙烧时间为2 h，采用浓度为25vol%的硫酸溶液在80℃下浸出3 h时，镓浸出率为98.38%。

关键词: 镓, 棕刚玉烟灰, 焙烧-浸出工艺, 杂质Si