Sequential extractions on mine tailings samples after and before bioassays: implications on the speciation of metals during microbial re-colonization

Mine tailings may be remediated using metal tolerant microorganisms as they may solve the limiting conditions for healthy development of plants (i.e., low organic mater content and poor physical conditions). The aim of this study was to investigate the consequences of microbial colonization on the chemical speciation of trace metals. Surface samples from the Valenciana mine tailings (Guanajuato, Mexico) were used for long-term bioassays (BA), which consisted in the promotion of microorganisms, development on tailings material under stable laboratory conditions (humidity, temperature, and light exposure). A five-step sequential extraction method (exchangeable, carbonate/specifically adsorbed, Fe–Mn oxides, organic matter (OM)/sulfide, and residual fractions) was performed before and after BA. Extraction solutions and leachates were analyzed by inductively coupled plasma-mass spectrometry. OM content, cationic exchange capacity, and pH values were also assessed before and after BA. The results indicate that trace elements are generally present in nonresidual fractions, mainly in the Fe–Mn oxides fraction. The concentration of total Zn, As, Se, Pb, and exchangeable Cu and Pb is above the recommendable limits for soils. Despite the high bioavailability of the former elements, biofilms successfully colonized the tailing samples during the BA. Cyanobacteria and green algae, heterotrophic fungi, aerobic bacteria, and anaerobic bacteria composed the developed biofilms. Chemical controls of trace elements could be attributed to absorption onto inorganic complexes (carbonates, metal oxides), while biofilm occurrence seems to enhance complexation and immobilization of Cr, Ni, Cu, Zn, As, and Pb. The biofilm developed does not increase the bioavailable forms and the leaching of the trace elements, but significantly improves the OM contents (natural fertilization). The results suggest that biofilms are useful during the first steps of the mine tailings remediation.     

酸性矿山废水中石灰岩包壳作用研究

研究石灰岩包壳作用有助于深入了解酸性矿山废水(AMD)在富含石灰岩的金属硫化物尾矿中的释放机制。采用AMD滞留浸泡石灰岩颗粒试料的实验方法,研究在酸水饱和条件下石灰岩次生包壳的形成作用。研究表明,AMD的Fe含量是影响石灰岩包壳作用的主因之一。在高Fe浓度(如1 029~1 033 mg/L)的AMD中,石灰岩颗粒表面可依次沉淀富Al相、石膏、纤铁矿(吸附Zn、Cu及As等),发生石灰岩包壳/钝化作用,使溶液维持酸性;而在低Fe浓度(6.71~74.8 mg/L)的AMD中,次生包壳难以生成,石灰岩得以大量溶解释碱并充分中和溶液中的H~+,使溶液达到中性。因此,Fe硫化物含量较高(如Fe含量10.62%、S含量5.70%)的石灰岩尾矿,由于其氧化后可生成高Fe浓度的酸性水而导致石灰岩包壳作用,具有释放AMD(及重金属)的危险,应注意防控。     

吉林红旗岭镍矿区尾矿地球化学特征研究

文章通过对红旗岭矿区尾砂数据的分析研究,对矿产资源的再度利用提出合理有效的方案,为矿产资源的二次开发开辟新的道路.在红旗岭尾矿库进行尾矿取样研究分析,测试尾砂中的元素含量,分析尾砂中元素的分布规律,依据工业品位要求,以及尾矿含水率等数据初步估算红旗岭矿区尾矿镍金属储量;对镍高品位值地段分析以及尾砂抽稀试验,为红旗岭尾矿...     

张马屯铁矿尾矿制砖开发应用研究

通过综合分析张马屯铁矿尾矿基本特性,对张马屯铁矿尾矿进行了铁尾矿砖生产试验研究。结果表明,利用张马屯铁矿尾矿,采用压制成型法,可以制备出MU10等级以上的建筑用砖,颜色一致性好,铁尾矿砖为灰色,抗冻性良好。认为利用尾矿制备建筑用砖是一条很好的尾矿利用途径,具有明显的经济效益和广泛的应用前景。     

四川稀土矿尾砂的稀土元素和微量元素地球化学特征及开发利用意义

四川是我国轻稀土的重要产地,稀土开采至今已有二十多年的历史,积存了大量尾砂。尾砂中仍然有丰富的稀土资源,但这部分资源究竟有多大的量、能不能再次回收,如何回收,则是当务之急。为查明稀土尾砂中各类元素的分布特征,本文对A、B、C、D四个稀土矿山的尾砂开展了稀土元素和微量元素地球化学特征的初步研究。结果表明:尾砂中稀土元素配分特征继承了原矿石,稀土氧化物含量普遍偏高(0.78%~2.12%),均超过了现行工业指标的边界品位(0.5%~1.0%),且老尾砂的稀土含量高于新尾砂;除了富集稀土元素之外,B尾砂中Sr含量超过10%,C矿区尾砂中Sr含量为2.7%,A矿区尾砂中Ba含量可达1.8%。同时,不同矿区的尾砂中Mo、Bi、Pb、Ag等有用元素发生了不同程度地富集(值得综合回收利用),尤其是Mo达到了边界品位(磁选后的尾砂Mo含量达到2.275%)。本文提出,今后不仅要加强保护四川稀土尾砂,而且需对富集的有用元素采取恰当的方式加以综合回收。     

一种基于 BP 神经网络的尾矿坝沉降预报方法

基于BP神经网络建立尾矿坝沉降预报模型,重点对BP神经网络的拓扑结构和学习算法进行研究。并以某尾矿库初期坝的沉降监测数据为例,对模型的拟合、预测精度进行验证。实例表明,BP神经网络自学习、自组织能力强,具有极强的线性逼真能力,能够准确地反映输入、输出变量之间的非线性关系,有效地表征尾矿坝的沉降变形规律,对即将发生的变形情况做出科学、合理的预报。     

The nature and engineering behavior of carbonate soils at Bombay High,India

Abstract

This paper presents the results of a laboratory investigation undertaken to study the nature of two submarine carbonate soils from Bombay High off the west coast of India, as well as to study the shear and plasticity behavior of their sand and silt‐clay fractions, respectively. Scanning electron micrographs reveal that the carbonate content in both soils is comprised primarily of nonskeletal particles of various types. X‐ray diffraction and infrared absorption analyses indicate that in one soil the carbonate fraction consists of calcite and aragonite minerals, whereas in the other soil dolomite is also present. The non‐carbonate fraction of both soils is comprised primarily of quartz and feldspar, and also some clay minerals. The nature of the carbonate fraction of the two soils indicates that they were formed by different depositional processes.

During drained triaxial shear the nonskeletal sand grains of both soils exhibit a lower degree of crushing when compared with that of the skeletal carbonate sands, and thus appear to be stronger foundation material.

Although the carbonate contents of the silt‐clay fractions of the two soils are similar, they exhibit markedly different plasticity characteristics . This is probably because of the microlevel cementation produced by carbonate material in one soil.

This study leads one to the conclusion that carbonate content alone should not be treated as a parameter which controls the engineering behavior of submarine soils; the nature and form of carbonate material must also be identified.     

Estimation of potential pollution from mine tailings in the San Pedro River (1993–2005), Mexico–US border

The San Pedro River (SPR) is located in northern Sonora (Mexico) and southeastern Arizona (USA). SPR is a transboundary river that develops along the Sonora (Mexico) and Arizona (USA) border, and is considered the main source of water for a variety of users (human settlements, agriculture, livestock, and industry). The SPR originates in the historic Cananea mining area, which hosts some of the most important copper mineralizations in Mexico. Acid mine drainage derived from mine tailings is currently reaching a tributary of the SPR near Cananea City, resulting in the contamination of the SPR with heavy metals and sulfates in water and sediments. This study documents the accumulation and distribution of heavy metals in surface water along a segment of the SPR from 1993 to 2005. Total concentrations of Cd, Cu, Fe, Mn, Pb, and Zn in surface waters are above maximum permissible levels in sampling sites near mine tailing deposits. Nevertheless, a significant decrease in the Fe and SO₄ ²⁻ in surface water (SO₄ ²⁻: 7,180–460.39 mg/L; Fe: 1,600–9.51 mg/L) as well as a gradual decrease in the heavy and transition metal content were observed during the period from 1994 to 2005. Approximately 2.3 km downstream of the mine tailings, the heavy metal content of the water drops quickly following an increase in pH values due to the discharging of wastewater into the river. The attenuation of the heavy metal content in surface waters is related to stream sediment precipitation (accompanied by metal coprecipitation and sorption) and water dilution. Determining the heavy metal concentration led to the conclusion that the Cananea mining area and the San Pedro River are ecosystems that are impacted by the mining industry and by untreated wastewater discharges arising from the city of Cananea (Sonora, Mexico).     

实现科学管理确保两库安全生产

结合马钢集团南山矿业公司尾矿库安全管理工作实践,分析了尾矿库安全工作的特点及其重要性,介绍了安全生产管理工作的具体做法、有益的探索和成功的经验,提出了加强安全检查,狠抓隐患整改,推行现场管理,建立安全防护体系的建议,努力寻求一条实现科学管理,确保尾矿库安全生产的有效途径.     

基于冀东金厂峪金矿尾矿综合利用的矿物特征

金属尾矿具有污染环境和资源再利用的双重特点。从综合利用的角度, 对冀东金厂峪金矿尾矿化学成分、矿物组成, 以及矿物粒度、解离度等进行了测试分析, 以寻求适合该尾矿综合利用的途径。分析结果表明: 金厂峪金矿尾矿属低铁高铝高硅尾矿; 矿物组成以石英和长石为主, 含少量的白云石、云母、方铅矿等矿物; 尾矿粒度以细砂为主; 尾矿中石英含量大于30%, 与其他矿物连生关系简单。综合利用建议: ①制备高纯度二氧化硅; ②制备生产烧结砖等建筑材料; ③制备微晶玻璃、釉面材料等高附加值产品; ④制备环保材料、土壤改良剂、矿物肥料等产品; ⑤作为井下充填材料。