Influence of Drainage with High Levels of Water-Soluble Salts on the Environment in the Verhnekamskoe Potash Deposit,Russia

Saline drainage from slurry storage facilities can deteriorate the properties of clay barriers in the beds of embankment dams and slurry ponds and cause saline drainage to infiltrate into groundwater. The chemistry of slurry material, drainage, springs, surface water, and soils was studied near the slurry storage facility of the Verhnekamskoe potash mine (Russia). Our study showed that the Na–Cl type mine drainage water, with high amounts of nitrogen compounds, increased the salinity of the groundwater and surface water, and the river valley ecosystems. As a result of ion exchange and leaching, the soil, groundwater, and surface water have elevated levels of \({\text{C}}{{\text{a}}^{2+}}\), \({\text{M}}{{\text{g}}^{2+}}\), \({\text{SO}}_{4}^{{2 - }},\) and \({\text{F}}{{\text{e}}_{{\text{total}}}}\), and extremely high \({\text{~N}}{{\text{a}}^+}\) and \({\text{C}}{{\text{l}}^ - }{\text{~}}\) values. Iron-rich precipitates and hydrogen sulfide tend to form down-gradient in the saline, water-logged seepage areas.     

Hydrogeochemical Characteristics of Groundwater at the Xikuangshan Antimony Mine in South China

The hydrogeochemical influence of the Xikuangshan antimony mine on groundwater quality was investigated by analyzing groundwater from 24 springs in the area for major and trace elements. The samples had a pH of 7.6–8.5; total dissolved solids ranged from 125 to 607 mg/L. The groundwater was dominated by alkaline earths (Ca²⁺ + Mg²⁺) over the alkalies (Na⁺ + K⁺), and weak acids \(\left( {{\text{HCO}}_{ 3}^{ - } } \right)\) over strong acids \(\left( {{\text{SO}}_{4}^{2 - } + {\text{Cl}}^{ - } } \right)\). Calcite was generally supersaturated and gypsum was always undersaturated, while dolomite was undersaturated in 34 % of the samples. Iron was negatively correlated with Ca²⁺, Mg²⁺, and \({\text{SO}}_{ 4}^{ 2- }\), which is consistent with Fe removal during acid buffering. Scatter diagrams and correlation coefficients between the major ions indicate dissolution of carbonates and gypsum as major processes, which could promote calcite precipitation.     

The Hydrogeochemistry of Arsenic in the Clara Mine,Germany

Abstract.   The oxidative dissolution of primary arsenic-bearing sulfide minerals in barite-fluorite veins is a potential source of arsenic in the Clara Mine. Geological structures, especially the mineral veins, provide potential pathways for the water. The highest arsenic concentrations are found in ground water within the eastern part of the mine. Arsenic and major ions are positively correlated and provide evidence that arsenic is likely derived locally from the water-vein/water-rock interaction. Geochemical modeling with PHREEQC shows all the arsenate mineral phases to be significantly undersaturated, although secondary arsenate minerals are common in the oxidized part of the deposit. The mine waters plot near the boundary of Fe(OH)₃ and Fe²⁺ in the pH-Eh diagram for the As-Fe-S-H₂O-system. Arsenic occurs as the 5-valent species and . Statistical analysis illustrates a strong association between As, Fe, pH, and HCO₃. Oxidation of the primary As-bearing minerals, such as pyrite and arsenopyrite, and the subsequent behavior of the oxyanion, arsenate, generally controls the distribution and speciation of arsenic. The low concentrations of dissolved As is due to co-precipitation and adsorption of arsenate by Fe, Al, and Mn (oxy)hydroxides.     

Assessment of Soil and Water Contamination at the Tab-Simco Coal Mine: A Case Study

In 1996, the Tab-Simco site, an abandoned coal mine 10 km southeast of Carbondale, Illinois, was listed as one of the most highly contaminated AMD sites in the mid-continent region. A suite of impacted soil and water samples were collected from various locations to characterize the current extent of AMD pollution, following standard U.S. EPA protocols. The mean pH of soil and water samples were found to be 2.69 and 2.07, respectively. The mean sulfur content of the soil samples was 0.5 %. The AMD-impacted soils contained high concentrations of Fe, Zn, Ni, Cr, Cu, Pb, and As. The AMD also contained high concentrations of Fe, As, Zn, Pb, Cr, Al, Cd, Cu, and Ni, as well as \({\text{SO}}_{4}^{2 - }\), all of which were significantly above their U.S. EPA permissible limits for surface water.     

Geomechanical conditions for quasi-resonances in geomaterials and block media

Conclusions  Based on voluminous information about relations between the dimensions of the central zones of crustal earthquakes and various energy classes of underground explosions, as well as mine shocks and man-induced tremors, therefore, the hypothesis that we had previously advanced relative to the quasi-resonant mechanism of their manifestation is confirmed. Here, the geomechanical conditions for the development of quasi-resonances associated with the inducement of pendulum waves are characterized by the dimensionless energy criterion k:

Biochemical and genomic facets on the dissimilatory reduction of radionuclides by microorganisms – A review

Development of environmentally sustainable technologies for remediation of radionuclides is paramount because of their long-term persistence in different ecological niches and acute toxic and teratogenic effects on human, terrestrial and aquatic life. The radionuclides U (VI), Tc (VII), Pu (VI) and Np (V) are enzymatically reduced to environmentally benign U (IV), Tc (IV), Pu (IV) and Np (IV), respectively by anaerobic microorganisms for production of energy and/or as a process of detoxification for their survival. These anaerobic microorganisms produce the oxidoreductase class of enzymes for the metabolism of radionuclides. These microorganisms have potential applications for the in situ environmentally friendly mitigation of radionuclides in subsurface environments. Appropriate knowledge on the biochemical and genetic pathways of radionuclides reduction by microorganisms will not only provide information on the fate and dynamics of these compounds in subsurface geological environments but also help to implement best management practice(s) for immobilization of these toxic compounds in waste effluents generated by the mining and nuclear industries. This review describes the phylogenetic diversity of radionuclides-reducing microorganisms present in the environment, various enzymatic systems associated with the reduction of radionuclides, and identification of genes involved in regulation of different enzymatic redox reactions.     

Copper leaching from waste electric cables by biohydrometallurgy

This study examines the leaching of copper from waste electric cables by chemical leaching and leaching catalysed by Acidithiobacillus ferrooxidans in terms of leaching kinetics and reagents consumption. Operational parameters such as the nature of the oxidant (Fe³⁺, O₂), the initial ferric iron concentration (0–10 g/L) and the temperature (21–50 °C) were identified to have an important influence on the degree of copper solubilisation. At optimal process conditions, copper extraction above 90% was achieved in both leaching systems, with a leaching duration of 1 day. The bacterial leaching system slightly outperformed the chemical one but the positive effect of regeneration of Fe³⁺ was limited. It appears that the Fe²⁺ bio-oxidation is not sufficiently optimised. Best results in terms of copper solubilisation kinetics were obtained for the abiotic test at 50 °C and for the biotic test at 35 °C. Moreover, the study showed that in same operating conditions, a lower acid consumption was recorded for the biotic test than for the abiotic test.     

Effect of loess for preventing contamination of acid mine drainage from coal waste

Acid mine drainage (AMD) that releases highly acidic, sulfate and metals-rich drainage is a serious environmental problem in coal mining areas in China. In order to study the effect of using loess for preventing AMD and controlling heavy metals contamination from coal waste, the column leaching tests were conducted. The results come from experiment data analyses show that the loess can effectively immobilize cadmium, copper, iron, lead and zinc in AMD from coal waste, increase pH value, and decrease Eh, EC, and SO ₄ ^2? concentrations of AMD from coal waste. The oxidation of sulfide in coal waste is prevented by addition of the loess, which favors the generation and adsorption of the alkalinity, the decrease of the population of Thiobacillus ferrooxidans, the heavy metals immobilization by precipitation of sulfide and carbonate through biological sulfate reduction inside the column, and the halt of the oxidation process of sulfide through iron coating on the surface of sulfide in coal waste. The loess can effectively prevent AMD and heavy metals contamination from coal waste in in-situ treatment systems.     

Effects of the complex loading of diabase

Condusions An experimental investigation of the dilatant properties of rock was conducted under a simple proportional loading right up to failure with determination of characteristics of the three-dimensional strength chart, as well as for its complex cyclic loading formulated from piecewise-linear segments of the path of a proportional load (or deformation) increment and partial unloading with measurement of the components of the tensor of strains, which are equal to those of the assigned stress tensor.It is established that dilatancy has different signs, depending on the type of complex stress state: all components of the strain tensor were compressive under pure shear, while one or two of the components of the strain tensor were obtained as tensile components for other ratios of stress-tensor components.Volume changes during plastic deformation appeared with the specimens subjected to a complex cyclic loading, when there is no similitude between the deviators of the stress and strain tensors. Under a complex cyclic loading, the passage of rock through a state of pure shear yields a consolidating effect, especially if the component of the stress or strain increment has the same Lodei—Nadai parameter during unloading (µ=0).It is established that maximum rock strength is attained in a state of pure shear with a higher hydrostatic component of the stress ternsor (under generalized shear).The author is deeply grateful to Academician of the Academy of Mining Sciences, Doctor of Physical and Mathematical Sciences, V. N. Oparin, for his discussion of the study and valuable comments and suggestions.The study was conducted with the financial support of the Russian Foundation for Fundamental Research (Grant 93-05-08643).Translated from Fizikotekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 45–52, September–October, 1996.     

A Simplified Anaerobic Bioreactor for the Treatment of Selenium-Laden Discharges from Non-acidic,End-Pit Lakes

Selenium (Se) contamination of aquatic resources and its mitigation is of global concern. Anaerobic bioreactors are the most promising method for treating Se-laden water in end-pit lakes resulting from intensive coal mining and waste rock leachate in the Canadian Rockies. This study assessed the suitability of a bioreactor system to treat non-acidic, coal mine effluent containing 85 μg/L of Se, near Grande Cache, AB, Canada, while making the system as cheap as possible using locally available materials. We successfully used a sediment inoculum from the same end-pit lake as the effluent source to obtain sulfur/Se-reducing bacteria and mixed the inoculum with mulch, manure, gravel, limestone, and bone meal to comprise the ‘active substrate’ for the bioreactors. The anaerobic bioreactors reduced >95 % of the total Se in the inflow water with a flow rate of ≈0.2 m³/h. Se removal was not related to water temperature, which declined from 17 to ≈2 °C in November, suggesting water can be treated regardless of temperature. The use of manure as a bacterial carbon/nitrogen source introduced Escherichia coli into the downstream environment, but after a short elevated concentration, the abundance of E. coli dropped below water quality guidelines. We were able to show that successful Se reduction can be achieved using an anaerobic bioreactor design and locally available material. This design kept the building and maintenance price lower than previous reactors, making the approach promising for larger scale applications and making bioreactors a more cost accessible remediation technology for non-acidic end-pit lakes.     

A Bauxsol™-based Permeable Reactive Barrier for the Treatment of Acid Rock Drainage

Abstract.   Permeable reactive barriers (PRBs) have generally been used to treat low flow and/or low contaminant loads of acid rock drainage (ARD). Bauxsol, a product made from seawater-neutralized red mud (a by-product of alumina refining) buffers pH at 8.8 and has been shown to remove >99% of heavy metals loadings at >1000 meq/kg, which would make it an ideal medium for PRBs. Unfortunately, Bauxsol is very fine-grained (>90% of the material <10 µm) and therefore, possesses a very low hydraulic conductivity. Consequently, sand/Bauxsol mixtures were trialed to determine hydraulic conductivity and ARD treatment capacities. Column tests indicated that the sand/Bauxsol mixtures maintain a higher hydraulic conductivity when used to treat ARD than when used with tap water. A 75:25 sand: Bauxsol filter with a 130 mm thick layer of reactive media had a hydraulic conductivity of 3.06 x 10^-5 m/s and except for Al, treated a highly contaminated ARD to ANZECC (2000) drinking water guidelines. A field trial of a 1 m³ PRB (70:30 sand:Bauxsol mixture) with a hydraulic conductivity of 9.8 x 10^-5 m/s treated about 45,000 L of highly contaminated ARD to the ANZECC (2000) drinking water standards, and about 27,000 L of this water had heavy metal loadings reduced to the ANZECC (2000) Protection of Aquatic Ecosystem guideline of >90% species protection.The metal binding preference of Cu>Pb>Zn>Mn displayed by the PRB is consistent with the pKa of hydration values and it appears that MOH⁺ formation dominates the removal of these metals. However, other removal processes appear to apply for Fe, Al, and Cd. Overall metal removal efficiencies ranged from 91.22% for Mn to >99.99% for Cu. Analysis of dried spent Bauxsol indicates that bound metals are not readily leachable, allowing the spent media to be disposed safely in a landfill.     

Monitoring the stress in a rock column on the basis of memory effects around a borehole

Conclusions Computer simulation shows that monitoring of the stress state of columns on the basis of emissional memory effects in the near-borehole rock requires a priori geological information on the orientation, dimensions, and density of the initial microcracks. Conditions for the interpretation of monitoring data are favorable in the presence of a system of initial microcracks oriented at an angle to the axis of the column, where 15°40° or 50°75°. The hydrosensor pressure P_gr obtained as a result of monitoring is directly proportional to the axial (vertical) stress in the column. The possibility of using this method in the case of random microcracking and in conditions when the crack system is oriented at = 0–15°, 40–50°, or 75–90° requires further — primarily experimental — investigation.Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 2, pp. 30–34, March–April, 1995.     

Removal of Trace Metals from Acid Mine Drainage Using a Sequential Combination of Coal Ash-Based Adsorbents and Phytoremediation by Bunchgrass (Vetiver [<Emphasis Type="Italic">Vetiveria zizanioides</Emphasis> L])

Potentially scalable low-cost treatment methods for acid mine drainage (AMD) are very limited. We used a sequential combination of adsorption and phytoremediation by bunchgrass (Vetiver [Vetiveria zizanioides L]) in a semi-batch system to remove Zn, Mn, Ni, and Cu from AMD. The objectives were: (1) to compare the removal of these metals by raw and NaOH-activated coal ash (NaOH-CA); and (2) to determine the effect of sequencing adsorption and phytoextraction on metal removal. The NaOH-CA adsorbed significantly more metals than raw coal ash (RCA) in both batch and semi-batch fixed column experiments, demonstrating the effectiveness of NaOH hydrothermal activation, which forms zeolites. Adsorption by NaOH-CA removed 59.1, 95.7, 67.6, and 77.9% of the Zn, Mn, Ni, and Cu, respectively, compared to 50.6, 95.1, 30.2, and 60.5% for the RCA. Metal removal by phytoremediation was generally less than that by adsorption, accounting for between 3.4 and 54.6% for both adsorbents. Phytoremediation following adsorption by NaOH-CA removed 89.2–99.9% of the metals compared to 70.8–98.5% when phytoremediation followed adsorption by RCA. Overall, relatively high metal removal efficiencies were attained, considering the acidic conditions (pH?<4), at hydraulic residence times of 1 to 5 days. Using coal ash to treat AMD is potentially a low-cost and environmentally friendly option for minimizing the adverse public health and environmental risks associated with both wastes.     

Electric field during seepage of grout

Conclusions 1. The value of the potential occurring as a result of sorption of ions of the mineralized solution by the filtering medium in the form of a fractured rock mass is tens of mV and depends more on the structure of the rock and less on the concentration and composition of the solution.2. In the case of plane-radial flow of the solution the distribution of the potentials and seepage field strength in the injection zone depends on the pressure distribution along the length of the flow from the injection borehole (for grouts — with consideration of sedimentation of the solid particles and filtering the liquid phase) as well as on the permeability of the medium.3. The seepage zone represents a space-charged body whose potential in the external medium depends on the effective seepage radius.Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 52–56, July–August, 1995.