Abstract A two stage hydrochloric acid leaching process is proposed for the treatment of lepidolite and recovery of alkali metals. The separation characteristics of aluminum and fluoride in the leachate were also determined. The transformation of lepidolite into silica-like residue was tentatively identified through X-ray diffraction measurements. The leach liquor was heated and concentrated and by evaporation to drive off to remove some of the hydrogen chloride and hydrogen fluoride from the acidic leachate, followed by cooling to deposit crystals. This yielded an overall hydrogen chloride and hydrogen fluoride removal of 25.4% and 2.52%, respectively. The main components of the crystals were aluminum and potassium chlorides, with small amounts of fluoroaluminate, polyaluminum chloride, and aluminum hydroxyfluoride. The crystals were calcined at 623 K, with a further 43.9% of hydrogen chloride and 4.33% of hydrogen fluoride being driven off and captured by adsorption equipment, which was beneficial for the subsequent separation of impurities. Investigation of the major mineral phases revealed that lower temperature calcination of the crystals tended to produce less-soluble polyaluminum chloride, aluminum hydroxyfluoride, fluoaluminate, and alumina. Water leaching of crystals after calcination at 623 K gave a leach liquor with 7.74 g/L of lithium, 0.15 g/L of aluminum and 0.25 g/L of fluoride. The fluoaluminate in the leach liquor led to the production of secondary precipitates after neutralization. The [AlFn]3-n species were partially dissociated to F− and Al(OH)4− at a strongly basic pH. The residual aluminum and fluoride concentrations were 0.01 g/L and 0.05 g/L, respectively, at the pH of 9. Since alkali chlorides such as lithium chloride are very soluble, there was less lithium loss during neutralization than in the corresponding sulfate system.

中文翻译：

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锂云母盐酸浸出过程中铝和氟化物的处理

摘要 提出了锂云母处理和碱金属回收的两段盐酸浸出工艺。还测定了渗滤液中铝和氟化物的分离特性。通过 X 射线衍射测量初步鉴定了锂云母向二氧化硅状残留物的转化。将浸出液加热并浓缩，并通过蒸发从酸性浸出液中除去一些氯化氢和氟化氢，然后冷却以沉积晶体。这导致氯化氢和氟化氢的总去除率分别为 25.4% 和 2.52%。晶体的主要成分是氯化铝和氯化钾，还有少量的氟铝酸盐、聚氯化铝和羟基氟化铝。晶体在623 K下煅烧，另外43.9%的氯化氢和4.33%的氟化氢被吸附设备驱除和捕获，有利于后续杂质的分离。对主要矿物相的研究表明，晶体的低温煅烧往往会产生溶解度较低的聚氯化铝、羟基氟化铝、氟铝酸盐和氧化铝。在 623 K 下煅烧后结晶的水浸出得到含有 7.74 g/L 锂、0.15 g/L 铝和 0.25 g/L 氟化物的浸出液。浸出液中的氟铝酸盐导致中和后产生二次沉淀。[AlFn]3-n 物质在强碱性 pH 值下部分分解为 F- 和 Al(OH)4-。残留的铝和氟化物浓度分别为 0.01 g/L 和 0。