Geochemistry of Perched Water in an Abandoned Underground Mine, Butte, Montana

Abstract.  The Lexington tunnel is the last accessible underground mine working in the Butte, Montana mining district. Used as recently as 1993, the tunnel and adjacent workings have been abandoned for over 10 years. Although the Lexington tunnel is over 200 m above the regional water table, perched water is present over much of its extent. Mine water near the portal is moderately acidic (pH 4 to 5), with extremely high concentrations of metals, including Cu (up to 1000 mg/L) and Zn (up to 1400 mg/L). In the middle reaches of the tunnel, the quality of the water is much better, with near-neutral pH, high bicarbonate alkalinity, and lower concentrations of heavy metals. The low acidity and metal content is attributed to a lack of pyrite and other sulfides in this portion of the mine, as well as the presence of carbonate minerals, such as rhodochrosite (MnCO₃), in exposed veins. Sulfide minerals are more widespread further back in the tunnel, and are now oxidizing rapidly, leading to pockets of severe acid drainage (pH< 3, dissolved Zn up to 5000 mg/L). Geochemical modeling suggests that the near-neutral waters—the most voluminous type encountered in the Lexington tunnel—are close to equilibrium saturation with rhodochrosite and hydrous Zn-carbonate (ZnCO₃•H₂O). The Eh of these waters is most likely controlled by redox reactions involving dissolved Mn²⁺ and secondary, Zn-rich, hydrous Mn-oxides. In contrast, the Eh of the acidic waters appears to be controlled by reactions involving Fe²⁺ and Fe³⁺. Most of the acidic waters are saturated with K-jarosite, which forms delicate, straw-like dripstones at several localities. Decaying mine timbers could be an important renewable source of organic carbon for heterotrophic microorganisms, such as iron- and sulfate-reducing bacteria, especially deeper in the mine workings where the ground is saturated with anoxic ground water.     

贵州菱锰矿高梯度磁选过程中矿物结构及其磁性能变化

通过一粗一扫高梯度磁选实验,讨论了磁选过程中贵州菱锰矿各阶段矿物的结构、磁性能与分选效果之间的关系,结果表明,所有阶段产品均具环内顺磁行为,且在较小的局部区域内,它们具有不同的矫顽力。磁滞回线的对比分析表明,铁磁性矿物(黄铁矿的氧化物)在菱锰矿物磁选中交互作用,导致无法分离,也很好验证了总铁含量居高不下,其一直伴随着菱锰矿。     

贫锰矿酸浸制取硫酸锰的工艺研究

为了有效利用现存的锰矿资源,以两种铁、磷含量差别较大的菱锰矿为代表,根据低磷高铁和高磷低铁两种贫锰矿石化学成分的特征,在实验室规模上研究了两种菱锰矿单独以及混合进行酸浸取制备硫酸锰以便生产电池用电解二氧化锰的基本工艺条件。提出了硫酸浸取过程中的一些主要工艺参数,在合理利用低磷高铁菱锰矿资源的前提下,用低磷高铁菱锰矿与高磷低铁菱锰矿按１．５∶１ 的比例混合,在浸取温度为９０～９５℃,浸取时间为２ ｈ,酸矿比为０．６９∶１,液固比为６∶１ 的条件下,该混合矿的碳酸锰浸取收率可大于８５％ ,总锰回收率比单独利用低磷高铁菱锰矿提高了将近１０％ ,而且反应体系过滤所需要的时间在原有基础上缩短了大约１ 倍。因此,利用低磷高铁菱锰矿生产碱性电池用电解二氧化锰是可行的。     

响应面法优化氯化铵焙烧浸出低品位菱锰矿工艺

为确定氯化铵焙烧水浸法处理低品位锰矿的最佳工艺,考察了焙烧温度、焙烧时间、氯化铵与锰矿的质量比等因素对锰浸出率的影响。在单因素条件实验基础上,以锰浸出率为响应值,采用Box-Behnken响应曲面分析法优化了反应条件。氯化焙烧水浸处理低品位锰矿最优条件:焙烧温度为460 ℃、焙烧时间为90 min、氯化铵与锰矿的质量比为1.42。响应面法建立的模型预测锰浸出率为94.71%,实验值为94.59%,两者偏差不大,方法可行。     

高铁菱锰矿制取硫酸锰的工艺研究

针对高铁锰矿无法充分利用的问题,实验对高铁菱锰矿为原料制备硫酸锰的工艺条件做了考察,重点解决了高铁菱锰矿在硫酸酸浸取过程中出现料浆黏稠、中和反应困难的问题。实验得到最佳工艺条件：浸取温度为90 ℃、液固质量比为5.5∶1、酸矿质量比为0.69∶1、浸取时间为2 h、过滤温度约为70 ℃。在此条件下,以高铁菱锰矿为原料制备硫酸锰的工艺可顺利进行,总锰收率比传统工艺提高5%~8%,过滤操作时间则缩短为传统工艺的1/3。     

高磷菱锰矿焙烧-氨浸实验研究

采用焙烧-氨浸工艺对重庆城口地区的高磷菱锰矿进行脱磷提锰研究,在热力学分析的基础上,考察了焙烧温度、焙烧时间对高磷菱锰矿分解率、活性以及锰浸出率的影响,并综合分析它们的交互作用,得到最佳焙烧工艺条件为:焙烧温度650℃,焙烧时间100 min。所得焙砂用16 mol/L氨水常温浸出60 min,锰浸出率为73.89%;浸出液蒸发后得到的MnCO₃产品中锰品位43.51%、磷含量0.012%。     

用菱锰矿为原料制备硫酸锰的工艺研究

介绍了以菱锰矿为原料,用硫酸浸出法制备硫酸锰的工艺路线,详细讨论了各种因素对锰浸出率及产品质量的影响,进而对老工艺进行了改进,优化出了最佳工艺条件,试验结果表明,锰浸出率为９８．２％,抽滤回必率为９１．％,浓缩,烘干及粉碎收率为９６．５％,产品总收率为８６．５％,产品质量符合国家标准。     

菱锰矿制备硫酸锰的工艺研究

介绍了以菱锰矿为原料,用硫酸浸出法制备硫酸锰的工艺路线。详细讨论了各种因素对锰浸出率及产品质量的影响,进而对老工艺进行了改进,优化出最佳工艺条件。试验结果表明：锰浸出率为９８．２％;抽滤回收率为９１．３％;浓缩、烘干及粉碎收率为９６．５％;产品总收率为８６．５％,产品质量符合国家标准     

菱锰矿原地溶浸试验研究

概述了锰矿的生产现状，提出了原地溶浸开采低品位菱锰矿新方法，给出了菱锰矿溶浸实验结果。     

Possibility of Manganese Ore Use in Water Treatment

The results are presented for the investigations into the catalytic properties of carbonate and oxide manganese ores in extraction of bivalent iron and manganese ions from underground waters. The phase transformations of rhodochrosites during thermal modification are examined, and the optimum regimes of ore calcination are determined for obtaining the catalytic-active oxide forms.