Tungsten Mine Research Articles

Water–Rock Interaction and Geochemical Processes in Surface Waters Influenced by Tailings Impoundments: Impact and Threats to the Ecosystems and Human Health in Rural Communities (Panasqueira Mine, Central Portugal)

The present and past mining activity left several abandoned tailings and dams in the Panasqueira tin–tungsten mining area. Seasonal water samples and stream sediments were collected during two different periods (rainy and dry seasons) and analyzed for a wide range of major and trace elements, in order to define the present hydrochemical situation. Rain waters interact with the altered sulfides stored in the tailings which generate runoff waters with high metal concentrations. The waste material derived from the exploitation enhanced acidification and metal-releasing processes, due to the increase in the specific surface, which favors the oxidation of sulfide minerals. Acid drainage and high metal(loid)s (Cd, Fe, Mn, Zn, Cu, As) concentrations in solution were observed in waters leaching the Panasqueira tailing deposits. In dry season, generally the acidic waters, enriched in metals, evaporate progressively depositing sulfate efflorescences characteristic of acidic environments. The elements distribution in precipitated minerals helps in the interpretation of aqueous geochemical data. Aqueous concentrations may be attenuated by goethite, gibbsite, and/or ferrihydrite precipitation in the oxidation zone through adsorption processes. The use of these waters for human consumption and for irrigation represents a threat to humans as they have a potential carcinogenic risk, especially due to the As concentrations. The acid water precipitation is present on the stream sediments, with concentrations exceeding the toxicity limits. Stream sediments are good receptors of metals and metalloids transported by waters. The enrichment factor values, of heavy metal(loid)s from Casinhas stream and Zezere river sediments, are extremely high in Ag, As, Cd, and Cu revealing enrichments for these potential toxic elements. I geo values shows that samples are strongly to very strongly polluted for Ag, As, Bi, Cd, and Cu. According to the consensus-based SQGs, 80 % of the samples were classified at the level of great concern and adverse biological effects are to be expected frequently in this area.

Tungsten distribution in soil and rice in the vicinity of the world's largest and longest-operating tungsten mine in China.

The objective of this study is to investigate tungsten (W) contamination in soil and its enrichment in rice in the area of the world's largest and longest-operating W mines in China. Root zone soil and rice plants were sampled at 15 sites in the agricultural field adjacent to W mines and analyzed for Al, Fe, Mn, Sc, and W contents and W chemical forms in the soil samples and W contents in the rice root, stem, leaf, and grain samples. Results showed that W content in the soil ranged from 3.99 to 43.7 mg kg−1, with more than 90% of W in the residual fraction, showing its low mobility and bioavailability. Average W contents in the rice root, stem, leaf, and grain were 7.06, 2.34, 4.76, 0.17 mg kg−1, respectively. In addition, they were linearly independent of W content and chemical forms in the soil. Average enrichment factor values were 0.39, 0.13, 0.28, and 0.01 for the root, stem, leaf, and grain, respectively. In can be concluded that W mining activity in the Dayu county contaminated the nearby agricultural soil and led to W bioaccumulation in the rice. This may pose a health risk to residents via food and soil ingestion, which should be a focus of scrutiny.

Particle Size Fraction and Arsenic Partitioning in Tailings and Sediments in Lianhuashan Tungsten Mine, Southern China

A series of tailings and sediments samples were collected from Linahuashan tungsten mining area. Particle composition, arsenic concentrations and arsenic speciation distribution in the tailings and sediments were investigated. The proportion of large particle (> 170 μm) in the tailings varied from 37% to 50%. Arsenic (As) concentrations in the tailings ranged from1889 mg·kg-1to 3135 mg·kg-1. The sediments upstream were similar to those in the tailings in particle composition, As concentrations and speciation distribution. The sediments in the middle or lower reaches of the stream contained finer texture and lower As concentrations than the tailings. Compared to the tailings, Acid waste water with a lot of tailings particle enter the stream. Most of larger particle in acid waste water settled upstream, and smaller particle and soluble As precipitated in the middle or lower reaches of the stream. Smaller particle fraction contained higher percentages of Fe-As, Ca-As and Al-As, while larger particle fraction contained higher percentages of FeOc-As and Res-As.

Tungstate adsorption onto oxisols in the vicinity of the world's largest and longest-operating tungsten mine in China

Tungstate adsorption in soils is critical to understand tungstate mobility and bioavailability, but study of this is lacking.

Compressive strength of tungsten mine waste- and metakaolin-based geopolymers

Neuro-fuzzy approach has been successfully applied to a wide range of civil engineering problems so far. However, this is limited for geopolymeric specimens. In the present study, compressive strength of different types of geopolymers has been modeled by adaptive neuro-fuzzy interfacial systems (ANFIS). The model was constructed by 395 experimental data collected from the literature and divided into 80% and 20% for training and testing phases, respectively. Curing time, Ca(OH)2 content, NaOH concentration, mold type, aluminosilicate source and H2O/Na2O molar ratio were independent input parameters in the proposed model. Absolute fraction of variance, absolute percentage error and root mean square error of 0.94, 11.52 and 14.48, respectively in training phase and 0.92, 15.89 and 23.69, respectively in testing phase of the model were achieved showing the relatively high accuracy of the proposed ANFIS model. By the obtained results, a comparative study was performed to show the interaction of some selected factors on the compressive strength of the considered geopolymers. The discussions findings were in accordance to the experimental studies and those results presented in the literature.

Elemental characterization of plants and soils in Panasqueira tungsten mining region

Purpose Mining activities represent a current source of pollution due to the large release of trace elements from mineral particles into the soil, atmosphere, and ecosystems. In active or abandoned metal-mining areas, direct discharge from mining deposits is one of the most common processes of contamination.

Using 222Rn as a tracer of geodynamical processes in underground environments

Radon levels in two old mines in San Luis, Argentina, were measured and analyzed, with the aim to assess the potential use of this radioactive noble gas as a tracer of geological processes in underground environments. La Carolina gold mine and Los Cóndores tungsten mine are today used as tourism mines. CR-39 nuclear track detectors were used for this purpose. Measurements were performed during both winter and summer seasons. The findings show that in these environments, significant radon concentrations are subject to large seasonal fluctuations, due to the strong dependence on natural ventilation with the outside temperature variations. For both mines, higher concentration values of 222Rn were observed in summer than in winter; with an extreme ratio of 2.5 times between summer and winter seasons for Los Cóndores mine. The pattern of radon transport inside La Carolina mine revealed, contrary to what was believed, that this mine behaves as a system with two entrances located at different levels. However, this feature can only be observed in the winter season, when there is a marked difference between the inside and outside temperatures of the mine. In the case of Los Cóndores mine, the radon concentration pattern distribution is principally established by air current due to chimney-effect in summer and winter seasons. In both cases, the analyses of radon pattern distribution appear as a good method to trace air currents, and then localize unknown ducts, fissures or secondary tunnels in subterranean environments.

Geochemistry, water balance, and stable isotopes of a “clean” pit lake at an abandoned tungsten mine, Montana, USA

The Calvert Mine is a small tungsten-rich (scheelite) skarn deposit in a remote, mountainous region of southwest Montana, USA. The open-pit mine closed in the 1970s and subsequently flooded to form a pit lake that is roughly conical in shape, 30m deep and 120m in diameter, with no surface inlet or outlet. The lake is holomictic with a groundwater flow-through hydrology and an estimated residence time of 2.5–5y. Water isotopes show that the lake is at an approximate steady state with respect to water balance and has experienced 30% evaporation. The lake has a near-neutral pH, exceptional clarity, and extremely low concentrations of nutrients, sulfate, and most metals, including tungsten. Manganese concentrations are slightly elevated and increase with depth towards the sediment–water interface. Despite seasonally anoxic conditions in the deep water, dissolved Fe concentrations are orders of magnitude lower than Mn, suggesting that insufficient organic carbon is present in the sediment of this oligotrophic lake to drive bacterial Fe reduction. Based on stable isotope fingerprinting, diffuse seepage that enters a nearby headwater stream at the base of a large waste-rock pile can be directly linked to the partially evaporated pit lake. However, this seepage has neutral pH and low metal concentrations, and poses no threats to the environment. Stable isotopes of dissolved inorganic carbon (DIC) and dissolved oxygen (DO) are used to track the relative importance of photosynthesis and respiration with depth. In summer, a zone of high productivity exists near the base of the chemocline, releasing DO that is isotopically light. Respiration exceeds photosynthesis below the Secchi depth, which causes DO concentrations to approach zero towards the bottom of the lake. In winter, thick ice and snow cover prohibits photosynthesis. However, because of the low nutrient content, most of the volume of the lake remains oxic through the winter. Overall, the Calvert Lake is a good example of a pit lake formed from metal mining that has excellent water quality, which is a result of its favorable geology (paucity of sulfide minerals) and hydrology (flow-through lake with short residence time in a temperate climate).

Monazite and xenotime U–Th–Pb geochronology by ion microprobe: dating highly fractionated granites at Xihuashan tungsten mine, SE China

Zircon, monazite, and xenotime have proven to be valuable chronometers for various geological processes due to their commonly high-U–Th and low common Pb contents. However, zircons that have crystallized in highly fractionated granites often have such high-U contents that radiation damage can lead to scattered U–Pb ages when measured with secondary ion mass spectrometry (SIMS). In this study, monazite and xenotime were separated from a number of highly fractionated granites at the Xihuashan tungsten mine, Southeast China, for alternative dating methods by SIMS. For monazite analysis, obvious excess 204Pb signal (mainly from interference of 232Th144Nd16O2 ++) was observed in high-Th (>2 wt%) monazite, which hinders 204Pb-based common Pb corrections. A 207Pb-based common Pb correction method was used instead. By employing power law relationships between Pb+/U+ versus UO2 +/U+, Pb+/Th+ versus ThO2 +/Th+ and suitable exponentials, monazites with ThO2 contents in the range of ~3–19 % do not exhibit this matrix effect. Independent SIMS U–Pb ages and Th–Pb ages of three phases of Xihuashan granite samples were consistent with each other and yielded dates of 158.7 ± 0.7, 158.0 ± 0.7, and 156.9 ± 0.7 Ma, respectively. Xenotime does show marked matrix effects due to variations of U, Th, and Y [or total rare earth element (REE), referred as ΣREE hereafter] contents. Suitable correction factors require end-member standards with extremely high or low U, Th, and Y (or ΣREE) contents. No excess 204Pb was observed, indicating that the 204Pb-based common Pb correction method is feasible. Independent 207Pb/206Pb ages can be obtained, although multi-collector mode is necessary to improve precision. The main difficulties with dating xenotime are when high-Th (U) mineral inclusions are ablated. We can identify when this occurs, however, by comparing the measured UO2 +/U+ and ThO2 +/Th+ with those in xenotime standards. Three xenotime samples from the first phase of Xihuashan granite yielded a weighted mean 207Pb/206Pb date of 159.5 ± 4.4 Ma (MSWD = 1.0) and a 206Pb/238U date of 159.4 ± 0.9 Ma (MSWD = 1.6), which are consistent with monazite U–Pb and Th–Pb ages from the same granites. This study demonstrates that monazite and xenotime are better SIMS chronometers for highly fractionated granites than zircon, which can yield doubtful ages due to high-U contents.

Heavy Metal Contamination and Environmental Concerns on Orchard at Abandoned Tungsten Mine, Southern China

A series of stream water, soil and fruits samples in the orchards were collected from Lianhuashan tungsten area in Guangdong Province. The concentrations of As, Cd, Pb, Zn, Cu and Ni in the samples were determined. This study targeted at the impacts of Lianhuashan wasteland on the orchards at the downstream. The results showed that the stream water was severely polluted by heavy metals, especially As and Cd, with low pH value and high electric conductivity (EC). Compared to the background orchards, the soils in the orchards at the downstream were polluted by As and Cd. The fruits in the orchards surrounding the polluted stream were seriously polluted by As and Cd. Acid waste water derived from the tailings of Lianhuashan tungsten mine entered the streams and resulted in elevated concentrations of heavy metals, lower pH values and higher EC in the stream water. The polluted streams caused soils and fruits pollution by As and Cd in the surrounding orchards.

Concentrations and chemical forms of heavy metals in agricultural soil near the world’s largest and oldest tungsten mine located in China

Tungsten (W) mining has taken place in Ganzhou in China for about 100 years. Such long-term W mining may release large amount of metals to soils and waters around these mines. Twenty soil samples were taken from the area around the W mines and 10 soil samples from an area much farther away. These soil samples were analysed for physicochemical properties, heavy metal content and their chemical forms. Results show that long-term W mining significantly increased both total and labile contents of Cd, Cu, Pb and Zn, but did not, or only slightly, increased the total content of Co, Cr and Ni in the soil near the mine. Average enrichment factor (EF) in the agricultural soils was 4.0, 2.4, 2.2, and 2.0 for Cd, Cu, Pb and Zn, respectively. The labile fraction was dominated by the carbonate-bound fraction for Cd (54.5%) and organic matter-bound fraction for Cu (37.9%), while the major labile fractions for Pb and Zn were associated with carbonates (30.2% and 6.4%), oxides (17.9% and 10.6%) and organic matter (9.2% and 18.8%). Consequently, there is a need to be cautious about Cd in the soils contaminated by W mining.

The Analysis and Evaluation of Heavy Metal Pollution in Wastewater of Tungsten Mine Area

A systematic research has been presented to the situation of heavy metal pollution in the wastewater which flows through the mining area, tailings area, farmland and rive in a tungsten mine area of Ganzhou. The content of Cu, Pb, Zn, Cd in the wastewater sample had been determined through directly inhalation by flame atomic absorption spectrometry(FAAS). While the content of Cr, Ni in the wastewater was also determined after the collected wastewater sample had been adjusted to pH＜2 with nitric acid. The results show that Pb, Zn is the main pollution factors in the region. The pollution in the mining area is the most serious. It is a bit lower in the tailings area than in the mining area. The content of Zn in the farmland has exceeded the standard. And the water in the river that closed mining area is normal. The mining area and tailings area is not suitable for the cultivation of edible plants. Cement ditches should be set up for the wastewater which flows through the farmland

Mitigation of Internal Expansive Reaction: The Role of Tungsten Mine Sludge

The concrete degradation caused by internal expansive reaction (IER) is a problem that affects many structures in the world. These reactions, which include the alkali-silica reaction (ASR) and the internal sulphatic reaction (ISR) related with delayed ettringite formation, are very dangerous, due the expansive behavior of products formed, that cause the cracking of concrete. So it is urgent to find preventive methods to avoid or mitigate the onset of these reactions in new structures. This work aims to show the applicability of sludge from a tungsten mine in the mitigation of the IER. To evaluate the effect of sludge in the mitigation of ASR and ISR, mortar and concrete mixes were produced with 30% (%in mass) of cement replacement. The results obtained so far allow stating that tungsten mine sludge as Portland cement replacement could be effective in the ASR and ISR mitigation.

Effect of immersion in water partially alkali-activated materials obtained of tungsten mine waste mud

Alkali-activated binders can be obtained using several sources of alumino-silicate materials, from calcinated clays, like kaolin, to industrial by-products, such as fly ash and, more recently, to calcinated waste mud from mining activities. The technology to obtain alkali-activated binders, also designated as geopolymers, is gaining increasing interest, since, in some cases, the properties of geopolymeric materials are superior to other existing cementitious systems. The research presented in this paper intends to deepen the knowledge regarding the properties of geopolymeric materials obtained using tungsten mining waste mud, particularly to study its behaviour after being immersed in water. However, in the current work, focus is given to follow compressive strength results in partially alkali-activated samples immersed in water, during different curing periods of time. Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy analysis (FTIR) were also utilised to investigate changes in the microstructure at different conditions of water immersion. A significant decrease in compressive strength occurring after 24h of immersion in water was found out, of specific partially alkali-activated materials, despite of its initial high compressive strength after 35days curing, at different temperatures.

Potential for reuse of tungsten mining waste-rock in technical-artistic value added products

Mining and quarrying activities in Europe generate approximately 55% of total industrial wastes, according to a recent Eurostat report. Most of these wastes are directly dumped on land or deposited in landfill sites. The first solution may lead to negative environmental impacts on land (removal of vegetation, deforestation, land slope changes and increased risk of erosion), water (pollutant transport through surface runoff, soil infiltration and contamination of water resources), may lead to the contamination of agricultural goods and may impose risks on human health. In Portugal, about 20% of industrial waste produced originates from mines and quarries, particularly from Panasqueira mining, one of the largest tungsten mines in the world. Currently, Panasqueira mining generates almost 100 tonnes of waste-rock, per day. Such waste-rock have accumulated over a number of years into very large heaps and it is desirable to seek new economic solutions that can contribute towards their reuse. In this context, this work discusses the potential for reuse of waste-rock piles of Panasqueira tungsten mine, which may be a case statement to be followed. The proposed solution described in this paper consists in developing innovative polymer-based composite materials, obtained from non-contaminated waste-rock tailings. Such materials must have suitable properties for technical-artistic value added applications, such as conservation, restoration and/or rehabilitation of historic monuments, sculptures, decorative and architectural intervention, or simply as materials for building revetments.

Sequential extraction and leaching characteristics of heavy metals in abandoned tungsten mine tailings sediments

The chemical speciation of potentially toxic elements (As, Cd, Cu, Pb, and Zn) in the contaminated soils and sulfides-rich tailings sediments of an abandoned tungsten mine in Korea was evaluated by conducting modified BCR sequential extraction tests. Kinetic and static batch leaching tests were also conducted to evaluate the potential release of As and other heavy metals by acidic rain water and the leaching behaviors of these heavy metals. The major sources of the elements were As-, Zn- and Pb-bearing sulfides, Pb carbonates (i.e., cerussite), and Pb sulfates (i.e., anglesite). The biggest pollutant fraction in these soil and tailing samples consists of metals bound to the oxidizable host phase, which can be released into the environment if conditions become oxidative, and/or to residual fractions. No significant difference in total element concentrations was observed between the tailings sediments and contaminated soils. For both sample types, almost no changes occurred in the mobility of As and the other heavy metals at 7 days, but the mobility increased afterwards until the end of the tests at 30 days, regardless of the initial pH. However, the mobility was approximately 5–10 times higher at initial pH 1.0 than at initial pHs of 3.0 and 5.0. The leached amounts of all the heavy metal contents were higher from tailings sediments than from contaminated soils at pH > 3.0, but were lower at pH < 3.0 except for As. Results of this study suggest that further dissolution of heavy metals from soil and tailing samples may occur during extended rainfall, resulting in a serious threat to surface and groundwater in the mine area.

A New Preparation Method of Fe-WC Composite Ceramic Powder through Ball Milling

The iron-based composite ceramic powder Fe-WC is produced by ball milling with synthetic tungsten mine and graphite. The process is accomplished through mechanical activation and reductive diffusion of the reactant powders during the milling process. The products are analyzed by means of XRD, DTA and EPMA. The results approved that the reaction does not carry through completely when the milling time is less than 8h. However, the composite powder of Fe and WC is gained by annealing from powders milled under 180V of the milling machine. The apparent activation energy of the reductive reaction is gradually decreased with the extending of milling time by mechanical activation.

A new endemic Diascia (Scrophulariaceae) threatened by proposed tungsten mining in the Western Cape

Diascia caitliniae K.E.Steiner is a new species of Diascia sect. Diascia from the northern end of the Piketberg, Western Cape. It resembles D. elongata in floral and seed morphology but is distinguished by having pedicels that are flattened and ribbon-like throughout their length and stamens and stigmas that are longer, more exerted, and strongly curved forwards. D. caitliniae is known from two localized populations on adjacent farms and is restricted to lower slopes in areas transitional between fynbos and renosterveld vegetation. It is strongly dependent on fire for germination and flowering. The largest population is threatened by the development of an open-pit tungsten mine and both populations are threatened by potential agricultural expansion up the slopes of the Piketberg.

유해원소 측정용 토양 인증표준물질 개발

토양 중 유해원소 분석용 인증표준물질 KRISS CRM 109-03-SSD를 개발하였다. 인증 대상 원소는 현행 토양환경보전법에서 규제하고 있는 비소, 카드뮴, 크로뮴, 구리, 수은, 니켈, 납, 아연이다. 인증표준물질 제조를 위한 출발물질은 강원도 상동의 텅그스텐 폐광 광미 더미에서 채취하였다. 출발물질은 선별, 건조, 분쇄, 체거름, 혼합, 병입, 살균의 일련의 과정을 거쳐 제조한 다음 ISO Guide 35의 절차를 준용하여 인증하였다. 측정에는 동위원소희석 질량분석법(ID-ICP/MS) 및 기기중성자방사화분석법(INAA)을 이용하였다. 균질도 평가는 ISO 13528의 부속서 B를 준용하여 실시하였다. 인증값은 서로 다른 두 가지 측정방법에 의한 분석 결과 또는 동일한 방법이지만 독립적으로 2회 반복 시행된 분석의 결과로부터 결정하였다. 최종으로 비소, 카드뮴, 크로뮴, 구리, 납, 니켈, 아연 7개 원소에 대한 인증값을 결정하였다. 수은은 낮은 농도로 인해 균질도 요건을 만족시키지 못해 철, 텅그스텐과 함께 참고값으로 제공된다. 환경감시목적으로 많이 이용되는 ISO 11466에 따른 왕수에 의한 용출시험 또한 실시하였다. 용출시험은 공립시험소 및 대학 시험소 등 6개 기관의 공동분석으로 수행되었다. 용출시험의 실험실간 편차는 인증값의 불확도에 비해 크게 나타났다. 용출시험에 대한 공동분석 결과는 참고값으로 제공된다. A certified reference material (CRM) of KRISS 109-03-SSD was developed for the analysis of hazardous elements in soil. The target elements were As, Cd, Cr, Cu, Hg, Ni, Pb, Zn being regulated by the Soil Environment Conservation Act. Starting material was collected from tailing dump of an unworked tungsten mine at Sangdong (Gangwon-do, Korea). The starting material under-went through a series of fabricating process steps of screening, drying, grinding, sieving, blending, bottling, sterilization and was certified according to the ISO Guide 35. Isotope dilution-inductively coupled mass spectrometry (ID-ICP/MS) and instrumental neutron activation analysis (INAA) were used for the measurement. Homogeneity was tested according to ISO 13528 annex B. The certified values were determined using the results from two different methods or from two independent measurements using a method. Finally, certified values of seven elements of arsenic, cadmium, chromium, copper, lead, nickel and zinc were determined. Mercury did not satisfied the criteria of homogeneity and the result would be provided for information only, together with iron and tungsten. It was also studied, the extractable fraction of elements by aqua regia according to the ISO 11466 protocol being frequently studied for the purpose of environmental monitoring. It was performed as a inter-laboratory study by 6 laboratories of a public institute and universities. Standard deviation among the laboratories was much bigger than the uncertainty of the certified value. The result of inter-laboratory study on the extractable fraction will be provided for information, only.

Durability and Environmental Performance of Alkali-Activated Tungsten Mine Waste Mud Mortars

Some authors argue that new binders are needed to replace ordinary portland cement (OPC) for enhanced environmental and durability performance. Alkali-activated binders have emerged as an alternative to OPC binders, which seem to have superior durability and environmental impact. This paper report results of a research project on the development of alkali-activated binders using waste mud from a tungsten mine. Abrasion and acid resistance of two ordinary portland cement (OPC) strength class concrete mixtures (C20/25 and C30/37) and several tungsten mine waste mud (TMWM) mixtures were evaluated. Acid resistance was performed by submitting samples to solutions of sulfuric acid, nitric acid, and hydrochloric acid, results of weight loss are reported. Abrasion resistance was assessed by the mass loss of cubic specimens when submitted to 1,000 rotations with the Los Angeles apparatus test machine. This study indicates that TMWM binders possess higher acid and abrasion resistance than OPC based concrete mixtures. The environmental assessment of the TMWM binders shows it can be considered an inert material which indicates that it could be used as a building material.