Tailings Mineralogy and Geochemistry at the Abandoned Haveri Au–Cu Mine,SW Finland

Fourteen samples from the Haveri Au–Cu mine tailings were studied by reflected-light microcopy, scanning electron microscopy, X-ray powder-diffraction, and sequential extraction methods, and 12 water samples were analyzed for total and dissolved elements to delineate the extent of sulfide oxidation and its impact on nearby surface waters. Water-soluble, adsorbed-exchangeable-carbonate (AEC), Fe (oxy)hydroxides, Fe oxide, and Fe sulfide fractions were extracted sequentially. The oxidation layer was found to vary from 50 to 140 cm: the upper part was nearly depleted in primary sulfides, especially pyrrhotite [Fe_(1?x)S] and pyrite (FeS₂); in the lower part, discontinuous cemented layers were detected. Secondary Fe (oxy)hydroxides and Fe oxyhydroxysulfates were abundant in the oxidation layer and were slightly enriched in trace elements, including As (up to 80 mg/kg), Cu (300 mg/kg), and Zn (150 mg/kg). Almost half of the As (average 25 mg/kg) were present as secondary minerals susceptible to redissolution. The pH of the vadose tailings varied from 2.46 to neutral, and the total sulfur content varied from 1 to 6.5% (average 2.9%). Aqua regia extraction showed that the Haveri tailings are characterized by low concentrations of the elements Cd, Cr, Pd, and slightly elevated concentrations of As, which are present at very low concentrations in the surface water (<6 μg/L). However, runoff that flows on top of the tailings and discharges into the nearby lake carries Co, Cu, Ni, and Zn (concentrations of each range from 500 to 1,800 μg/L). Additionally, dissolution of sulfides and Fe precipitates may mobilize trace metals in the ground water. Thus, overall, there is a small continuous release of AMD into Lake Kirkkojärvi, but the environmental impacts to the lake are presently small.     

Geochemical Behavior of Mine Tailings and Waste Rock at the Abandoned Cu–Mo–W Azegour Mine (Occidental High Atlas, Morocco)

The abandoned Azegour mine is located in the High Atlas Mountains of Marrakesh (Morocco), and was mined for Cu, Mo, and W. About 850,000 t of waste rocks and tailings were deposited on the surface and have been exposed to weathering for 40 years. The remaining acid-producing potential (AP), acid-neutralizing potential, and geochemical behavior of the Azegour Cu-and Mo-rich tailings were investigated. The tailings were found to contain 9.6–19 wt% sulfur, mostly as sulfate (gypsum, anhydrite, and jarosite) while the waste rocks contain less (1.25–6.58 wt%) sulfur. The waste rocks and tailings contain 0.21–9.24 wt% Mo and 0.003–2.78 wt% Cu. The gangue is mostly composed of quartz, talc, chlorite, pyrophyllite, actonolite, clinoptilolite, and alusite. Lead, zinc, cobalt, arsenic, titanium, and nickel are also present. The calcium, which is mainly expressed as calcite, gypsum, scheelite, and powellite, is present at higher concentrations in the waste rocks (18–22 wt% Ca) than in the tailings (4.7–8.6 wt% Ca). Static ABA determinations showed that the Azegour mine wastes still have high AP, 38–205 kg CaCO₃/t in the waste rocks and 46–387.7 kg CaCO₃/t in the tailings. This was confirmed in weathering cell tests, where the Azegour tailings leachate had a pH range of 1.98–3.19 and high concentrations of SO₄ (468–45,400 mg/L), Ca (230–675 mg/L), Fe (3–55,900 mg/L), Mn (0.1–1,430 mg/L), and Cu (2.3–9,000 mg/L). The Mo concentrations were high (35 mg/L) during the two first weeks of kinetics tests; W concentrations were below the 0.005 mg/L detection limit.     

Detection of Abandoned Coal Mine Goaf in China’s Ordos Basin Using the Transient Electromagnetic Method

Mine Water and the Environment - Early coal mining and management methods left a large number of unknown goafs in China’s important Ordos Basin, which has restricted the safe production in...     

Prediction of Acid Mine Drainage (AMD) and Metal Release Sources at the Küre Copper Mine Site,Kastamonu, NW Turkey

Mine Water and the Environment - Waste and lithological rocks were subjected to aqueous leaching, acid base accounting (ABA), and net acid generation (NAG) tests, and detailed mineralogical...     

Mobility of Be,Bi, F,Ga, Ge and W in Surface Water and the Water Quality Impact on Epilithic Diatoms Downstream of the Historical Yxsjöberg Mine Site,Sweden

There is a potential risk that the geochemical cycles of several critical metals will be affected when mining of these metals increases to meet the demand of green technology. The geochemistry of Be, Bi, Ga, Ge, and W, herewith called CM5, is lacking, yet is necessary to ensure responsible mine waste and water management. Beryllium, Bi, and W are all considered immobile, but in previous studies of skarn tailings in Yxsjöberg, Sweden, all three elements were mobilized. The tailings are enriched in CM5, together with pyrrhotite, calcite, and fluorite. The mobility and environmental impact of CM5 and F in surface waters downstream of the Yxsjöberg mine site, Sweden, were studied using monthly water samples from seven locations and analysis of diatoms at five of these locations. Bismuth, Ge, and W were present at low concentrations, transported in the particulate phase, and likely settled in the sediments hundreds of meters from the tailings. Beryllium and F were present at high concentrations and dominantly transported in the dissolved phase. At these pH conditions (5.6), Be should form insoluble hydroxides; however, elevated concentrations of dissolved Be were observed more than 5 km from the mine site. Diatoms downstream of the mine site were negatively affected by the mine drainage. The release of low quality neutral mine drainage will continue for hundreds of years if remediation actions are not undertaken since only a small portion of the tailings have weathered during 50–100 years of storage.

     

In Search of a Speciation Method for Arsenic in Mine-Influenced Waters: Is Differential Pulse Anodic Stripping Voltammetry the Answer?

Mine Water and the Environment - This study investigated whether differential pulse anodic stripping voltammetry (DPASV) with a solid gold electrode could be used for arsenic speciation of...     

Chemical and Water-Isotope Composition Unravels the Source and Evolution of the Kittilä Underground Mine Water,Kiistala, Finland

Mine Water and the Environment - Assessing the environmental impacts of underground mines requires that the mine water sources and the geochemical processes that alter their chemical composition be...     

A Note on the Influence of the Mine Tailings Released in the Córrego do Feijão Mine Disaster on the Water Bodies of Brumadinho,Minas Gerais,Brazil

Mine Water and the Environment - The rupture of the Córrego do Feijão iron mine Tailings Dam I killed at least 260 people and had major environmental and social impacts. We analyzed the...     

The Geochemical Behaviour of Mine Tailings from the Touiref Pb–Zn District in Tunisia in Weathering Cells Leaching Tests

Flotation tailings associated with the extraction of Pb and Zn in the Touiref mining district, Tunisia, contain galena, sphalerite, pyrite, and marcasite in a carbonate gangue. The geochemical behaviour of oxidized and unoxidised tailings were consistent with their mineralogical and chemical characteristics. The leaching proceeded under neutral to slightly alkaline condition (pH 7.3–8.5), and positive Eh (250–470 mV). The concentrations of sulfate and Ca released during the leaching tests were associated with the neutralization of acidity by carbonates and the dissolution of gypsum initially present in the tailings. The iron precipitated, but significant amounts of Zn (5–3,300 μg/L), Cd (3–18 μg/L), and Pb (28–83 μg/L) were released during leaching, with the latter two exceeding international environmental norms (5 μg/L for Cd and 10 μg/L for Pb).     

The Relationship Between Groundwater in the Nováky Coal Deposit and the Thermal Waters from the Bojnice High Block (Slovakia)

Slovakia is very poor in coal reserves but it is extremely rich in mineral and thermal water resources. The Nováky coal deposit is situated near the Bojnice spa, which is among the oldest and most important spas in Slovakia. Due to their proximity, there is a risk that coal mining could adversely affect the Bojnice thermal water resources. We evaluated the results from several surveys as well as groundwater monitoring (inflows to the mining area, overflows from surface wells, and groundwater levels relative to the aquifer systems) and groundwater chemical processes near the Nováky coal deposit and explained the relationship between the groundwater in the Nováky coal deposit and tectonically uplifted Bojnice High Block.

     

Chemometrics in Ascertaining Hydrogeochemical Characteristics of Coal Mine Discharge vis-à-vis Behaviour of Surface and Groundwater Resources of the Mahan River Catchment Area,Central India

We investigated the hydrogeochemical regime of an AMD-affected coal mining province. 98 water samples were collected over two seasons and analysed for 14 parameters. We attempted to discriminate the sources of variation of water quality using select multivariate techniques: display methods (principal component analysis) and unsupervised pattern recognition (cluster analysis). Most of the groundwater and river water were characterised by shallow freshwater facies (Ca–Mg–HCO₃ type), whereas the samples representative of mine water were of the Ca–Mg–SO₄ type. The mines of the area annually discharge 2901 t of solute loads, ranging from 91 to 1030 t/year. Various molar ratios suggest that dissolution of the silicates associated with the mixing process is the predominant solute acquisition processes that govern the water chemistry of the region besides AMD. The chemometric results indicated that only a few groundwater and river water samples had low pH and elevated total dissolved solids, and these were near the three mines that were affected by AMD. These results substantiate the effectiveness of the mine water treatment measures implemented at the mine sites.

     

Hydrochemical Analysis of Groundwater in Coastal Coal Mining Areas—A Case Study of the Liangjia Coal Mine,North China

To understand the hydrochemical characteristics and circulation pattern of groundwater in coastal coal mining areas, we analyzed 81 water samples from different water bodies in the Liangjia coal mine (LCM) area using multivariate statistical analysis and hydrochemical methods. The Quaternary groundwater (QW), accumulated water (AW) in the subsidence area, and mine water (MW) in the LCM all exhibit weakly alkaline to slightly saline water chemistry. The dominant cations and anions in the water are sodium (Na⁺) and chloride (Cl^?), reflecting the influence of seawater intrusion. Some ions in QW, AW, and MW exhibited significant annual variations, but Na⁺ and Cl^? concentrations increased with time. The water samples were divided into four categories through cluster analysis: C1 and C2 (bedrock water samples), C3 (water samples prominently affected by seawater intrusion), and C4 (QW and AW in the surface subsidence area). According to the Piper diagram, QW and AW in the surface subsidence area mainly correspond to the Na?Cl type, whereas the MW mainly consists of Na?Cl and Na?HCO₃ types. Factor analysis revealed four main factors: seawater recharge, HCO₃-rich bedrock water, alkaline water, and Quaternary groundwater (QW) with eigenvalues of 4.18, 2.44, 1.22, and 1.19 respectively, which explained 81.98% of the original data information. The comprehensive results of hydrochemical analysis and mathematical statistics indicated that the recharge sources of MW in LCM include seawater, QW, AW, HCO₃-rich bedrock water, and mixed water. Based on regional hydrogeological conditions, a preliminary groundwater circulation model of the coastal coal mining area was constructed. Groundwater generally flows into the Bohai Sea from southeast to northwest, and coal mining has changed the original local groundwater runoff patterns and intensified seawater intrusion.

     

Surface Soil Water Content Before and After Coal Mining and its Influencing Factors—A Case Study of the Daliuta Coal Mine in Shaanxi Province,China

The spatial variability in soil water content in the Daliuta mining area in western China was studied before and after coal mining using ground penetrating radar and geostatistical methods. The relationships among soil water content, soil physical properties, topographical factors, and vegetation density were analysed using classical statistics. The average surface soil water content changed slightly between the two detection events at the centre of the subsidence, from 0.084 cm³/cm³ to 0.079 cm³/cm³; there, the distribution of the soil water content was more closely related to terrain than any of the other factors being considered. Along the subsidence boundary, the surface soil water content decreased significantly after mining, from 0.099 cm³/cm³ to 0.083 cm³/cm³ at one location. The total soil porosity, soil organic matter, and soil clay content were positively correlated with soil water content before mining. However, after mining, the relationship between total soil porosity and soil water content significantly strengthened while the relationships between other soil physical and chemical properties and soil water content weakened. Vegetation was determined to be the main factor controlling the surface soil water content before and after coal mining at one location in a small (1,600 m²) area of the subsidence boundary.

     

Hydrochemical and Stable Isotope (δD and δ18O) Characteristics of Groundwater and Hydrogeochemical Processes in the Ningtiaota Coalfield,Northwest China

Mine Water and the Environment - Understanding the sources and mechanisms of groundwater recharge in the Ningtiaota Coalfield, an arid area in northwest China, is important for water resources...     

Origination and development mechanics of the Earth’s morphostructures. Part II: The nature of diatreme, karst and trappean formations, and the chicxulub crater origin

The article analyzes genesis of representative morphostructures of the Earth, and substantiates that their origin, similarly to the Patomsky crater, is associated with the hydrogen outgassing and pipe formation in the internal part of the Earth, or, to put it otherwise, with the development of different diameter ring shape structures in the hard shell of the planet. Evolution of all the structures can be described with the dilatancy-explosion model, independent of their dimension. The author explains the billions years history of integration of these endogenous structures into great families of different scale, age and depth ring structures. It is shown that this global process is based on the plume-tectonics.