矽卡岩型钼矿尾砂中重金属Mo的淋滤实验研究

Leaching experiments on heavy metal Mo release from sharn molybdenum ore tailings

运用动态淋滤法实验研究了辽宁葫芦岛地区矽卡岩型辉钼矿浮选法产生的尾矿中重金属钼的淋滤行为(15℃和35℃,淋溶液pH值4～9)。结果表明:淋滤液均呈碱性,钼的质量浓度为7.5～14.2mg·L-1,淋滤累积质量为54～69mg,占总钼的12.56%～16.54%;与Pb、Cu和Zn等重金属随酸性排水淋滤迁移不同,钼在碱性环境中具有较强迁移性;尾砂中斜长石和钠长石等矿物因具有较强的产碱能力形成了尾砂内部的碱性环境;尾矿中MoS2和MoO3在碱性环境下转化为MoO42-是迁移的主要机制。pH值为5～9时,淋滤累积质量与pH值正相关。因酸可溶态钼发生溶解,pH值为4淋滤累积质量大于pH值为5时的淋滤累积质量,排水仍为碱性。温度能够加速淋滤速率,35℃淋滤液中钼质量浓度比15℃的高7%～10%。因此,对该区尾砂应该设置标准尾矿库封存管理,否则将对环境造成严重影响。

The leaching of heavy metal Mo from sham molybdenite flotation tailings, in Huludao area of Liaoning province, was investigated by dynamic leaching （15 ℃, 35 ℃ and pH 4-9）. The results showed that the leachate was alkaline, and the concentration mass of Mo iron was 7.5 - 14.2 mg·L^-1. The leaching cumulative mass was 54 ~ 69 mg which was 12.56% ~ 16.54%account for the total Mo of tailings. In contrast to Pb, Cu, and Zn release from acid mine drainage, Mo behaved freely in alkaline circumstance. Because of the alkali producing potential of plagioclase and albitei in sham molybdenum tailings, the alkaline circumstance was formed in tailings. Translating into MoO4^2- from MoS2 and MoO3 was the main leaching mechanism. As a result, the leaching cumulative mass showed increased trend with increased pH （from 5 to 9）. But the leaching cumulative mass at pH 4 was more than pH 5, which was caused by the dissolved acetic acid extractable fraction. The concentration mass at 35 ℃ was 7% - 10%higher than at 15 ℃ resulting from the leaching velocity accelerated by temperature. The conclusion also showed that the tailings in this area must be sealed in standard tailings pond. Otherwise, that can cause environmental pollution.