With a decline in high-grade molybdenum reserves, the development of other types of molybdenum resources have received increasing attention. Vanadium shale is a multi-metal shale and fine-grained sedimentary rock comprising small grains and various minerals. After leaching and extracting vanadium, the solution often contains a low concentration of molybdenum. However, because of the low molybdenum concentration, many processing plants treat it as an acidic wastewater, which wastes molybdenum resources and carries the risk of environmental pollution. The leaching process of vanadium shale mostly involves high-temperature and high-pressure operations, which greatly increase the content of impurity ions such as aluminium and phosphorus in the pregnant leach solution. These impurity ions increase the difficulty in separating and recovering molybdenum. In this study, the adsorption and separation of molybdenum at leach liquor of low molybdenum concentration were investigated. The effects of different factors such as: (i) pH of feed solution, (ii) adsorption time, and (iii) presence of impurity ions, aluminium and phosphorus, on the adsorption and separation of molybdenum using five different anion-exchange resins, D201, D296, D301, D314, and D301R, were investigated. The static adsorption and desorption test results showed a molybdenum adsorption capacity of 222 mg/g at pH = 1.5 by the D301 resin. The desorption efficiency using 20% NH₄OH was 96.1%. The adsorption efficiencies of aluminium and phosphorus were 1.31% and 3.10%, respectively. This is a better choice for separating molybdenum from complex solutions. The experimental results from spectra and theoretical calculations showed that the -NH group of D301 resin was combined with the O atoms of MoO·3HO, Al(SO), and HPO by electrostatic attraction. The binding energies of these three species were − 311 kJ/mol, −231 kJ/mol, and − 62.0 kJ/mol respectively, indicating that D301 resin preferentially adsorbed MoO·3HO. Based on the above results, the D301 resin can adsorb molybdenum(VI) in complex solutions under low pH conditions, and this study is expected to promote the comprehensive recovery of valuable metals from vanadium shale.

中文翻译：

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含铝磷钒页岩酸浸溶液中低浓度钼(VI)的选择性阴离子交换吸附


随着高品位钼储量的下降，其他类型钼资源的开发日益受到关注。钒页岩是一种多金属页岩和细粒沉积岩，由小颗粒和多种矿物组成。浸出和提取钒后，溶液中往往含有低浓度的钼。但由于钼浓度较低，许多加工厂将其作为酸性废水处理，既浪费了钼资源，又带来了环境污染的风险。钒页岩的浸出过程大多涉及高温高压操作，使得富浸液中铝、磷等杂质离子的含量大大增加。这些杂质离子增加了分离和回收钼的难度。本研究对低钼浓度浸出液中钼的吸附分离进行了研究。不同因素的影响，例如：(i) 进料溶液的 pH 值、(ii) 吸附时间、(iii) 杂质离子、铝和磷的存在，对使用五种不同阴离子交换树脂吸附和分离钼的影响，对 D201、D296、D301、D314 和 D301R 进行了研究。静态吸附和解吸测试结果表明，D301树脂在pH = 1.5时对钼的吸附容量为222 mg/g。使用20%NH 4 OH的解吸效率为96.1%。对铝和磷的吸附效率分别为1.31%和3.10%。这是从复杂溶液中分离钼的更好选择。 光谱和理论计算的实验结果表明，D301树脂的-NH基团通过静电引力与MoO·3HO、Al(SO)和HPO中的O原子结合。这三种物质的结合能分别为-311 kJ/mol、-231 kJ/mol和-62.0 kJ/mol，表明D301树脂优先吸附MoO·3HO。基于上述结果，D301树脂可以在低pH条件下吸附复杂溶液中的钼(VI)，该研究有望促进钒页岩中有价金属的综合回收。