Water quality variation of mining-subsidence lake during the initial stage: cases study of Zhangji and Guqiao Mines

Four quarters?? water collecting and monitoring samples were done in the mining subsidence lakes of different water storing periods (2 to 7 years), considering the water storing time and pollution sources state of the subsidence lakes. The following indexes were discussed such as organic indexes (TOC, COD_Mn, BOD, COD), nutrient salts (TN, NH ₄ ⁺ , NO ₃ ^? , NO ₂ ^? , Kjeldahl Nitrogen, TP, PO ₄ ^3? ), etc. It is shown that water quality of the mining subsidence lake during the initial stage (2 years to 7 years) can stay relatively stable with a fluctuation during different quarters in a year, which can reach class III or IV of the Surface Water Environmental Quality Standard.     

Geochemical and Mineralogical Characterization of a Pyritic Waste Pile at the Anjir Tangeh Coal Washing Plant, Zirab, Northern Iran

Coal washing at the Anjir Tangeh plant, in Zirab, northern Iran, has produced more than 1.5 Mt of coal wastes. These waste materials were geochemically and mineralogically characterised to guide development of an appropriate remediation scheme. Three vertical trenches up to 4 m deep were excavated from the coal waste pile surface and 25 solid samples were collected at 0.5 m intervals. The samples were analysed for total concentrations of 54 elements, paste pH, SO ₄ ^?2 , CO ₃ ^?2 , and HCO₃ ^?. The lowest pH values were measured at a depth of 0.3 m. The upper portion (1 m) of one profile was moderately oxidised, while oxidation in the other two profiles did not extend more than 0.8 and 0.5 m beneath the pile surface. The waste piles have low acid-producing potential (15–21.87 kg CaCO₃/t) and high values of acid-neutralizing potential (0.06–96.2 kg CaCO₃/t). Fe, Al, S, Na, Mn, Pb, Zn, Cd, and Ag increased with increasing depth, while Mo, Sr, Zr, and Ni decreased with increasing depth. The results show pyrite oxidation at depth and subsequent leaching of the oxidation products. Mn, Zn, Cu, Pb, Ag, and Cd are the most important contaminants of concern at this site.     

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.     

Origin of nitrogen compounds in water infiltrating into porphyry quarry,Zalas, southern Poland.

The paper deals with the problem of the origin of nitric compounds in the mine water entering porphyry quarry. A hydrogeological study of the natural and disturbed ground water regimes as a consequence of quarrying have shown that fecal and domestic sewage was the main source of nitrogen compounds in the water entering the porphyry quarry. The sewage contaminated the surface water which in turn infiltrated into the porphyry within the cone of depression. In addition to that, NH ₄ ⁺ and NO ₃ ^? ions penetrated into the surface water as the result of washing of nitrogen out of the soil and a pa product of biochemical and chemical changes in the soil. A solution of unburnt explosives, used for the ground excavation was also a source of nitrogen compounds.     

Evaluation of pH Testing Methods for Sulfidic Mine Waste

Environmental assessment of solid mine waste is required throughout the life of a mine. This has driven the need for tools and practices to understand the current state of net acidity in mine wastes. Rinse and paste pH tests are commonly used in the initial screening of waste to provide a preliminary evaluation of its current net acidity. Such pH tests are particularly useful for assessing the chemistry of first flush waters draining sulfidic rocks and wastes. In this study, we compared nine different pH tests (rinse and paste pH tests as well as soil tests of the International Organization for Standardization ISO 10390:2005; American Society for Testing and Materials ASTM D4972-01 2007; Standards Australia AS4969.2-2008), using three different sulfidic rock samples and the acid–base accounting standard KZK-1. We observed significant variability in measured pH for the same samples using the different test methods. We show that different rinse and paste pH methods using different grain sizes and extraction solutions can result in different risk classification for ARD assessments. We recommend carrying out pH measurements using 0.01 M CaCl₂ solution, which results in more rapid, reproducible, and precise analyses than using deionised water.     

Changes in Efficiency and Hydraulic Parameters During the Passive Treatment of Ferriferous Acid Mine Drainage in Biochemical Reactors

The objective of this study was to evaluate the effects of different reactive mixtures and hydraulic retention times (HRTs) on hydraulic parameters (hydraulic conductivity, k_sat, and porosity) and the efficiency of passive biochemical reactors (PBRs) for treatment of ferriferous acid mine drainage (AMD). Five 10.7 L PBRs were filled with three reactive mixtures, containing either a carbon-rich substrate (60% w/w) or an inert/neutralizing agent (50% w/w). The PBRs were tested over a 450 day period using two qualities of iron-rich AMD (4 and 1 g L^?1 Fe in AMD1 and AMD2, respectively), and two HRTs, of 5 and 7 days. During the last week of the columns’ operation, a tracer test (5 g L^?1 of NaCl) was also performed, in addition to monthly measurements using the falling head method. Changes in HRT and k_sat were evaluated throughout the experiment. The PBRs increased the pH of AMD influents from 3.5 to 6 and efficiently removed Al, Cd, Cr, Ni, Pb, and Zn (>?90%), whereas Fe was only partially and inconsistently treated. No significant differences were observed among the three tested mixtures, regardless of the HRT or the AMD quality. Results from the tracer test and k_sat measurements showed no significant decrease in the initial values of the hydraulic parameters with time except for column 3, where a slight decrease was observed. Although sorption could have been important during the start-up of the PBRs, post-testing characterization of the spent reactive mixtures showed that the Fe was mainly retained as oxy-hydroxides and sulfides. Given the PBRs’ marginal effectiveness for Fe-rich AMD, pre-treatment removal of the iron is recommended.     

Virtual prototype simulation of hydraulic shovel kinematics for spatial characterization in surface mining operations

Hydraulic shovels are large-capacity equipment for excavating and loading dump trucks in constrained surface mining environments. Kinematics simulation of such equipment allows mine planning engineers to plan, design and control their spatial environments to achieve operating safety and efficiency. In this study, a hydraulic shovel was modelled as a mechanical manipulator with five degrees of freedom comprising the crawler, upper, boom, stick, bucket and bucket door components. The model was captured in a schematic diagram consisting of a six-bar linkage using the symbolic notation of Denavit and Hartenberg (Ho and Sriwattanathmma 1989 Ho, C. Y. and Sriwattanathmma, J. 1989. Robot Kinematics Symbolic Automation and Numerical Synthesis, Norwood, NJ: Ablex.  [Google Scholar]). Homogeneous transformation matrices were used to capture the spatial configuration between adjacent links. The forward kinematics method was used to formulate the kinematics equations by attaching Cartesian coordinates to the schematic shovel diagram. Based on the kinematics model, a 3D virtual prototype of the hydraulic shovel was built in the Automatic Dynamic Analysis of Mechanical Systems (ADAMS) environment to simulate the motions of the hydraulic shovel with selected time steps. The simulator was validated using real-world data with animation and numerical analysis of the digging, swinging and dumping motions of the shovel machinery. The superimposed display of the deployment of the hydraulic shovel in three phases allows a detailed motion examination of the system. The numerical results of linear and angular displacements of the bucket tip and bucket door can be used to analyse the kinematics motion of the hydraulic shovel for its optimization. This simulator provides a solid foundation for further dynamics modelling and dynamic hydraulic shovel performance studies.     

Rotifer Diversity in the Acidic Pyrite Mine Pit Lakes in the Sudety Mountains (Poland)

The diversity of rotifers was studied in three artificial water bodies (Azure Lake, Yellow Lake, and Purple Lake), which were once pyrite mines. The physicochemical parameters and the zooplankton composition of the water were determined. Azure Lake had a pH of 3.4–6.9, conductivity values of 165–194 µS cm^??1, and low concentrations of sulphate, calcium, magnesium, copper, and iron, while the other lakes had a pH of 2.6–2.9, a conductivity of 1636–3400 µS cm^??1, and high concentrations of sulphate (up to 2863 mg dm^??3), Cu (up to 2650 µg dm^??3), and Fe (up to 178.3 mg dm^??3). The rotifer community in the lakes comprised 27 taxa (15 in Azure Lake, 13 in Purple Lake and 14 in Yellow Lake). We also found two species that are rarely observed in Poland (Aspelta cincinator and Elosa spinifera), and three species commonly found in acidic water (E. worallii, Cephalodella delicata, and C. hoodi). The types of rotifers in Azure Lake differed from those in the other two lakes. The Shannon–Weaver biodiversity index (H′) was the highest in Purple Lake (H′?=?1.255) and lowest in Azure Lake (H′?=?0.455). The effect of some of the physicochemical parameters on rotifer diversity is discussed.     

Unique Pit Lake Created in an Opencast Potassium Salt Mine (Dombrovska Pit Lake in Kalush,Ukraine)

We studied the physicochemical and biological characteristics of the Dombrovska pit lake in Ukraine. The lake formed in an abandoned opencast potassium salt mine and is one of the most saline inland water bodies in the world. It is 85 m deep (November 2015) and an annual inflow of about 2 Mm³ of water. The lake has two distinct layers. The mesohaline surface (0–5 m) layer is well oxygenated and slightly alkaline (pH?=?7.5–8.8). Its mineralization, expressed as dry mass, was 50–134 g dm^??3, and its electrical conductivity (EC) was 58–134 mS cm^??1. The underlying layer consists of hypersaline water with low amounts of dissolved oxygen, a neutral pH (6.7–7.4), high mineralization (179–420 g dm^??3), high EC (169–215 mS cm^??1), and higher concentrations of major anions and cations (except Ca²⁺) and nutrients than the overlying water. The vertical relationship between major ions and metals and the future salinity of the lake are discussed. In terms of zooplankton, in July we found living specimens of the rotifer Brachionus plicatilis and the ciliates Paradileptus elephantinus and Tindinnidium sp. as well as dead rotifers, cladocerans, and copepods (in total, 19 species), but only live B. plicatilis and 9 dead species in November. In the littoral part of the pit lake, we found the diatoms Nitzschia pusilla and some Halamphora species (H. borealis, H. tenerrima, H. acutiuscula), which favour highly saline waters.     

Tailings Weathering and Arsenic Mobility at the Abandoned Zgounder Silver Mine,Morocco

The abandoned Zgounder Mine (Morocco) was exploited for Ag from 1982 to 1990 and generated nearly 490,000 t of mill tailings before it was closed without being reclaimed. The tailings contain low concentrations of sulfide (mainly as pyrite, sphalerite, and galena) and carbonates (mainly dolomite). Silicates (muscovite, albite, chlorite, labradorite, actinolite, and orthoclase) occur in high concentrations. The most abundant trace elements are As, Ti, Fe, Mn, Zn, and Pb. We studied the geochemical behavior of the mine wastes to identify the main factors controlling drainage water chemistry. Particular emphasis was put on sorption phenomena to explain the low As concentrations in the leachates despite significant As levels in the tailings. Weathering cell tests carried out on various tailings produced two types of contaminated drainage: acidic and neutral. The kinetic test leachates contained high concentrations of some contaminants, including As (0.8 mg L^?1), Co (11 mg L^?1), Cu (34 mg L^?1), Fe (70 mg L^?1), Mn (126 mg L^?1), and Zn (314 mg L^?1). Acidity and contaminants in the leachates were controlled by dissolution of soluble salts and Fe hydrolysis rather than sulfide oxidation. Batch sorption tests quantified the significance of As sorption, and sequential extraction showed that most of the As sorption was associated with the reducible fractions (Fe and Mn oxides and oxyhydroxides).     

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.     

Accumulation of Arsenic and Copper by Bryophytes Growing in an Aquatic Environment near Copper Mine Tailings

Bryophytes with high As accumulation affinity were identified in the aquatic environment. We surveyed a stream near copper mine tailings and then conducted laboratory experiments to confirm As accumulation in the bryophytes with high As affinity. We found that a moss, Scopelophila cataractae, accumulates As in addition to Cu in aquatic environments and confirmed it in laboratory experiments. The highest value for As in S. cataractae from the field survey was 1300 mg/kg dry weight at relatively low As concentrations in the stream water (0.005 mg/L). In addition, Brachythecium plumosum and Rhynchostegium riparioides may also be useful bryophytes for accumulation of Cu and As, though the mechanisms of As accumulation might differ between these two bryophytes and S. cataractae.     

Pyrite Weathering in Reclaimed Shale Overburden at an Oil Sands Mine near Fort McMurray,Canada

Saline-sodic shale overburden associated with oil sand mining is a potential source of salt release to surface water and groundwater and can lead to salinization and/or sodification of reclamation covers. Weathering of shale overburden due to oxidation of sulphide minerals within the shale leads to sulphate (SO₄ ^2?) production and increased salinity. The controls on the rates of weathering of a shale overburden dump in the oil sands region of northern Alberta were determined from soil chemistry sampling and in situ monitoring of pore gases (O₂, CO₂, CH₄) in three shallow profiles (1.9–4.45 m deep) and one deep (25 m deep) profile under reclamation covers of varying thickness. Oxidation, defined by the depth over which O₂ concentrations were depleted, reached depths of approximately 1.1 m under the reclamation soil covers over a 6 year period after dump placement. Calculations of SO₄ ^2? production rates and weathering depths were consistent with numerical simulations of the diffusion and subsequent consumption of atmospheric O₂ in the overburden. The rate of SO₄ ^2? production during the 6 year weathering period estimated from direct measurements of solids chemistry ranged from 0.70 to 8.3 g m^?2 day^?1. The rates calculated from the oxygen diffusion models were within that same range, between 1.6 and 4.1 g m^?2 day^?1.     

Mathematical modelling for estimation of minewater inflow to a surface mining operation

Estimation of water inflow to a surface mining operation is a necessary requirement for mine drainage design. The water in a shallow surface mine may originate solely from a surface source and from the atmosphere in the form of precipitation. Water in deep mining excavations below the groundwater table may originate from a surface source or as atmospheric precipitation as well as from the groundwater system. Inflow of surface water to a mining excavation can be predicted by hydrological balance investigation of a mining catchment. The paper briefly describes the hydrological cycle of a mining catchment together with the technique of estimating inflow from a surface source. The groundwater inflow to a mining excavation is mainly a consequence of the interaction of groundwater system, hydrogeological characteristics of the rock mass and the mining geometry. The water inflow regime is determined by the incision of one or more aquifers by the mining excavation and the relative hydrogeological characteristics of the various aquifers. The paper identifies various possible flow regimes in the vicinity of mining excavation. The groundwater inflow can be estimated by one of the following techniques:

- Equivalent flow approach

- Two-dimensional flow equations

- Numerical techniques incorporating the Finite Element Method, Finite Difference Method or the Boundary Element Method.

     

The Impact of Mine Tailings on the Witwatersrand and the Surrounding Water Bodies in Gauteng Province,South Africa

The gross alpha and beta activity in treated water from one of the numerous gold mines in Gauteng province averaged 1.15?±?0.13 and 0.87?±?0.11 Bq L^?1, respectively. The average readings of the fissure water from the same mine were 0.56?±?0.10 and 0.52?±?0.11 Bq L^?1, respectively. Water samples collected at the foot of the Princess gold mine tailings dump in Gauteng province and from downstream, before the drainage joins other water sources, also had high average gross alpha and beta activity and high average concentrations of radionuclides. The hazard quotient value evaluated, based on ²³⁸U of the water sample types in these vicinities, was far above one, indicating that it may pose serious health risks to the inhabitants.     

Towards Regulatory Criteria for Discharging Iron-rich Mine Water into the Sea

Appropriate criteria are needed for regulating the discharge of mine water into the sea. Simply applying criteria developed for freshwater ecosystems to marine settings would be naïve and highly inappropriate because marine organisms have very different mechanisms for coping with high concentrations of cations than do freshwater species. Furthermore, the hydrodynamics and geochemistry of marine waters mean that certain processes that are very important in determining the magnitude of mine water impacts in freshwater ecosystems are largely irrelevant in the oceans. This is particularly the case relative to benthic smothering by ochre, which does not occur when mine waters are discharged to the sea. Visual impacts of mine water discharge are still important in marine systems, due to the possibility of developing unsightly “slicks” of suspended ochre on the water surface (albeit these are actually innocuous in ecological terms). Avoidance of ochre slicks is a common concern wherever ferruginous mine waters are discharged to coastal waters. Compilation of data from a range of case studies indicates that no visible plume of ochre would be expected where the rate of iron release is less than about 200 kg/day. Maintenance of iron loadings below this critical threshold can be ensured by calculating a target maximum iron concentration (Fe_MAX, in mg/L) for the final effluent (which must be achieved by treatment if necessary) using the simple formula: Fe_MAX = 2,314.8/Q _MAX, where Q _MAX is the maximum anticipated flow rate in litres per second from the mined system (pumped or flowing by gravity).     

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.     

Biodegradation of Biosolids Under Aerobic Conditions: Implications for Cover Materials for Sulfide Mine Tailings Remediation

Sewage sludge residue (biosolids) was investigated for its potential as a long-term tailings cover. Biosolids may prevent oxygen diffusion into underlying sulfide tailings through microbial aerobic biodegradation of organic matter. Biosolids were investigated at laboratory-, pilot-, and field-scale using analysis of total organic matter (TOM) mass reduction and O₂, CO₂, CH₄ concentrations to quantify the biodegradation rate. A 156-day, open microcosm experiment, in which the loss of biosolids mass over time at differing temperatures, mimicking ambient (20–22 °C), mesophilic (34 °C), and thermophilic (50 °C) conditions, indicated that TOM biodegradation was best in the mesophilic temperature range, with 14.8, 27.2, and 26.7 % mass depletion at ambient, mesophilic, and thermophilic conditions, respectively. The data was correlated to field-scale data that evaluated biodegradation rates via decreasing O₂ and increasing CO₂ concentrations. Field biodegradation rates were less than laboratory rates because lower mean annual temperatures (0.6–0.7 °C) diminished microbial activity. A calibrated model indicates that 20 % of a field application of biosolids will degrade within 2 years. However, the rate declines with time due to exhaustion of the most readily degradable organic fraction. If biodegradation cannot be maintained, the long-term effectiveness of biosolids as a covering material for mine tailings remains a concern.     

Die Erneuerung der Klinkerproduktion der Zementwerk LEUBE GmbH in St. Leonhard/Österreich

After conducting intensive studies as well as a feasibility study, Zementwerk LEUBE GmbH has taken the decision to install a new kiln line. Aims of the project were high fuel substitution rates, low energy consumption as well as lowest possible emissions simultaneously with a high degree of flexibility of the plant. The project investment of approximately 31.5 mio. € includes as follows:

• Raw meal dosing
• 5-stage preheater with calciner and combustion chamber in concrete structure with steel platforms
• Shift of an existing rotary kiln
• Kiln hood and grate cooler
• Cooler exhaust air filter
• Fuel handling (alternative fuel for calciner)
• Clinker transport
• Necessary connections to existing feeding and exhaust gas handling

The project was executed by a LEUBE team with a specialized EPCM-team (Engineering Procurement Consulting Management-Team) from A TEC Production & Services GmbH. The project started on 22 July 2009. The first clinker was produced on 20 October 2010 after an accident-free total erection phase of 15 months. After more than 4 years of production experience it can be summarized that all expectations and all guarantee values have been completely fulfilled. The yearly reduction of coal consumption amounts to approximately 8000 tons which correspond to a fuel substitution rate of approximately 70?%. The electric power consumption was reduced by approximately 20?% compared to the old kiln lines. The strict emission limits in the tourism area of Salzburg could be met without any difficulties. With the new kiln line it is possible to adapt the production according to the seasonal fluctuating cement sales (the production ratio is between 1000 tpd and 2000 tpd clinker). The system demonstrates an extremely high degree of flexibility in terms of different fuels, raw materials and throughput. Additional modifications in the area of raw mill and exhaust gas filter were effected in 2011/2012, which secures the clinker production at the plant in St. Leonhard in the future.