Secondary Sulphate Minerals in a Cyprus-Type Ore Deposit,Apliki, Cyprus: Mineralogy and Its Implications Regarding the Chemistry of Pit Lake Waters

The Apliki mine, a Cyprus-type massive sulphide deposit in Cyprus, was exploited for copper until the mid-1970s. Abandonment of the mine left a deep pit that now hosts a lake fed by surface runoff from the surrounding mineralized zone and hydrothermally altered basalt. Oxidation of the sulphide minerals and factors such as climate and terrain relief control the water–rock interactions that generate acid mine drainage (AMD), which ultimately affects and defines the quality of the lake waters. Pyrite and chalcopyrite constitute an almost inexhaustible sulphide source that leads to the formation of a variety of secondary iron and copper mineral phases. The secondary mineral assemblages in the ore zone are mainly iron, copper, and magnesium sulphates, whereas the lakeshore assemblage is dominated by magnesium-, calcium-, sodium-, and aluminum-bearing sulphate minerals. Near the lakeshore, the highly soluble iron sulphate salts dissolve in the lake water, increasing its iron content. Other less soluble salts are more stable and persist in the lakeshore environment. The precipitation and dissolution of efflorescent salts, and, to a lesser extent, the oxidative weathering of the remaining ore minerals, produce additional AMD. Due to the perpetual cycle of mineral dissolution and precipitation, the lake has a low pH (≈3) and contains high concentrations of some contaminants. The processes that contribute to the formation of the efflorescent mineral assemblages and their environmental impact on pit lake waters, and indeed the complete geochemical system, is a typical example of secondary mineral formation in Cyprus-type Cu-pyrite massive sulphide ore deposits.     

Environmental pollution from coal mining activities in the Enugu area Anambka state Nigeria

Hydrogeological studies of the Enugu coal mining area were carried out which included hydrogeochemical analyses of water samples. These analyses revealed high sulphate and iron content in the acid mine drainage water as well as high total dissolved solids’ (TDS) and low pH (acidity) values. The water issues from the Ajali Sandstone formation and the underlying carbonaceous Mamu Formation and is classified as hard water. As a consequence of under-mining this aquifer, huge volumes of (polluted) water has flooded the mines are channelled into some streams or rivers which in turn get chemically polluted. Remedial measures have been indicated which include the following:

1. the treatment of acid mine water before pumping into streams or river;
2. the disposal of mine spoil wastes in carefully prepared and designed disposal sites;
3. planned and detailed mapping of the fractures in the Manu Formation for more effective dewatering scheme and increased exploitation of the overlying Ajali Sandstone aquifer to reduce or limit the amount of water flooding the mines in the underlying Mamu Formation.

     

Experimental study for the particle size distribution of mine spoil pile cross section

The aim of the experiment is to analyze and view the distribution of gangue with different particle sizes in mine spoil pile cross section. According to the Dimensional method, ‘Pi’ theorem was employed first to abbreviate ten physical and mechanical parameters to three dimensionless groups, and then the similarity criterion and coefficient of the experiment were determined and calculated based on particle size distribution curve. The similarity model was designed and constructed to represent the process of the mine spoil pile. The profile of the final model shows that the small sized particles mainly compose the upper zone of the mine spoil pile, while the bottom of the pile is dominated by bigger sized particles, and the intermediate section presents a zigzag stripe cross-bedding structure which is composed by small-medium scale particles and medium-large scale particles. Each stripe has two critical angles: one is the angle in which gangue particles can maintain their stability condition, with approximate range from 24° to 26°; and the other is the angle in which particles can stop gliding downwards, approximately varying from 34° to 36°.     

The Combined Impact of Mine Drainage in the Ankobra River Basin,SW Ghana

This study assessed the combined effects of seven large-scale gold mines, one manganese mine, and scattered artisanal gold mining sites on the quality of water in the Ankobra Basin in a geologically complex terrain. Water samples from streams, boreholes, hand dug wells, and mine spoil were analysed. Scatter plots of trends among measured parameters were used to assess drainage quality and differential impacts. Drainage quality exhibits wide seasonal and spatial variations; the geology strongly influences the water chemistry. Areas with low pH (<5.5), and high sulphate ions and trace ions are suggestive of acid mine drainage while sites with high pH (>7.5), HCO₃ ⁻, subdued SO₄ ²⁻, and high trace ions are suggestive of sites where acid neutralization is effective. High metal sources are largely confined to mining operations in the Birimian formation with ores containing more than 2% sulphides. However, restricted high metal regimes are observed in drainage in the Tarkwaian formation associated with scatted sulphide-bearing dolerite dykes in the operational areas of the Tarkwa and Damang mines. Earlier studies disputed sulphides in the Tarkwaian formation until recently, when acid-generating dykes were discovered in operating pits. The most degraded waters emanate from the Prestea and Iduapriem mines, and to a lesser extent, the Nsuta mine sites, all mining Birimian rocks. The Tarkwa mine showed minimal metal loading. Zn, Cu, Ni, As, SO₄, pH, and specific conductance are essential and adequate parameters in determining if acid drainage is taking place at these sites, and are recommended for routine mine environmental monitoring.     

Groundwater problems in surface mining in the United Kindom

An outline of ground water problems in surface mining in the United Kingdom is presented. Sources of mine water in surface mining are described together with the operational problems created by adverse groundwater conditions. The effects of groundwater on the stability of excavation slopes, spoil slopes and superficial deposits are described with the aid of case histories.     

矿井地面排矸系统改造可行性研究

矿井地面排矸系统是保证矿井矸石排放需求,实现矿井煤炭生产持续稳定地增长的关键环节。针对鹤岗矿业集团公司益新公司矿井地面排矸系统现状及存在的主要问题,提出了系统改造的必要性和改造具体方案,取得了较好效果。     

Properties of fly ash stabilized haul road construction materials

ABSTRACT

Larger haul trucks are being used at surface mines in Canada thus requiring better haul roads to carry heavier loads. The availability of good quality aggregate to build haul roads is limited for prairie coal mines. However, most of these mines are located adjacent to coal-fired electrical power plants, which produce by-product fly ash as a waste. Fly ash can be used to increase strength and stiffness of soil and road bases.

Unconfined compressive strength tests conducted on various mixtures of fly ash, kiln dust, mine spoil, and coal seam partings showed that the cementing characteristics of unclassified fly ash from central Alberta coals was low. However, the addition of cement kiln dust, which is high in CaO, enabled the fly ash to exhibit significant cementing action.

Mixtures of fly ash, kiln dust, and mine spoil or coal seam partings had unconfined compressive strengths of about 1 MPa and elastic moduli of about 350 MPa after 14 to 28 days. This compares favourably with compacted mine spoil or coal seam partings which have estimated unconfined compressive strengths of less than 0.4 MPa and moduli of about 50 MPa. Thus fly ash stabilized mine spoil or coal seam partings were found to have potential for use in constructing haul road base and sub-base layers since maximum tire pressures on the running surface are less than 0.7 MPa.     

饱水岩石水稳试验及力学特性研究

针对岩石的水稳定性问题,利用赵楼、万福、南屯煤矿岩样,进行了系统的沉积岩水稳定性特征试验研究.结果表明:岩样的水稳定性差异随高岭石、伊利石和伊蒙混层的相对定量而变化,且受岩石裂隙率的影响;岩石饱水后,强度降低,受层理构造影响,抗压、抗拉破坏形态岩石多伴随或主要呈现层状破坏;岩石抗拉强度具有显著的时间效应,可用负指数进行表达.     

矿山岩土工程系统环境质量评价指标体系

矿山现行的环境影响评价及其提交的环境影响报告书,是将矿山开发视为单个建设项目且只注重污染物排放和简单数量分析的单要素评价.本文将矿山开发视为统一系统,充分考虑系统内矿石开采、废石场、尾矿库等岩土工程及其矿岩氧化淋滤产生的毒害物质对矿区及其区域水土环境潜在而长期的影响,建立矿山岩士工程系统环境质量评价的指标体系,以改变矿山环境评价的传统旧式,规范和监督矿山开采行为,实现矿业开发与环境保护的协调发展.     

江苏汤山金矿自然重砂找矿标志研究

汤山金矿是江苏省发现的唯一一个小型微细浸染型独立金矿床。基于汤山金矿区1∶〖KG-*2〗20万、1∶〖KG-*2〗5万自然重砂建库数据,结合矿床矿石矿物组合特征,选择褐铁矿、黄铁矿、砷矿物（雄黄、雌黄、毒砂）、辰砂、自然银、铅矿物（自然铅、方铅矿、白铅矿）、闪锌矿、自然金、铜矿物（黄铜矿、斑铜矿、蓝铜矿、孔雀石）、重晶石等作为主要标型矿物,通过ZSAPS20软件,应用GIS平台,圈定自然重砂组合异常。通过异常特征剖析发现,黄铁矿和褐铁矿为汤山金矿直接指示矿物,自然金、闪锌矿、辰砂、毒砂、重晶石为汤山金矿次一级指示矿物。在此基础上,结合地质找矿标志,建立汤山金矿地质—自然重砂找矿标志,为深入评价汤山金矿找矿潜力提供自然重砂方面的依据。     

Prevention of Acidic Groundwater in Lignite Overburden Dumps by the Addition of Alkaline Substances: Pilot-scale Field Experiments

Mining activities in the Rhineland lignite mining area in Germany have led to increased mineralisation and acidity of groundwater due to the oxidation of sulfide minerals. The potential benefit of adding alkaline substances (crushed limestone and a mixture of fly ash and crushed limestone) to the overburden spoil was investigated using laboratory columns and pilot-scale field experiments. The latter tests were each conducted with 13 metric tons of overburden. A considerable improvement in water quality (decreased sulfate, iron, trace elements and acidity) was found in both scales of experiment. Similar improvements are expected in the limed overburden dump of the Garzweiler lignite mine.     

深露天煤矿倾斜条带跟踪内排开采程序

提出了一种适合于深露天煤矿的全新的开采程序--倾斜条带跟踪内排开采程序.解决了深露天煤矿如何尽早实现内排从而大量减少外排的问题.分析了该开采程序的工艺,介绍了该开采程序与以往开采程序的不同之处及其优越性.     

Environmental management of acid water problems in mining areas

Acid Mine Drainage (AMD) originates from the oxidation and leaching of sulphide minerals present in coal and metalliferrous ore bodies and gives rise to several environmental degradation problems. An investigation has been carried out to combat the acidic water problems. Results of this investigation indicate that application of anionic surfactant (sodium lauryl sulphate) and food preservatives (sodium benzoate and potassium sorbate) effectively abate the acid formation at low concentration levels (15–40 ppm) as tested in laboratory as well as at pilot-scale levels. Acidity, sulphate and iron concentrations are found to reduce by over 70 percent and remained low for more than three months after treatment. Thus this investigation demonstrates the management of these problems in an environmentally safe manner by controlling acid formation at its source.     

Spoil dump design and rehabilitation management practices (Australia )

Abstract

The environmental impact of mining and evolving environmental legislation has been receiving increased attention worldwide in the last two decades ( Bradfield, Shultz & Stone 1996). The potential impacts associated wim unstable spoil dumps from mine operations is the focus of concern both by the mining industry, environmental legislative agencies and members of the public. Engineered slopes of mine spoils may be stable at the end of construction, but they can deteriorate over time. There is thus the need to increase the base of knowledge on the existing practices of spoil dump design and rehabilitation. Information concluded from the analysis of the industrial survey carried out on Australian spoil dump management practices are presented in this paper.     

平煤五矿副井提升系统优化改造

通过对五矿副井提升系统优化改造,可以提高矿井提升系统的安全可靠性,降低事故影响,增大矿井提升系统提升能力,适应五矿高产高效和现代化矿井建设发展的需要具有极大的现实意义;为解决矿井提升系统优化改造开创了一条新的技术途径。     

Modelling the Long-term Release of Sulphate from Dump Sediments of an Abandoned Open Pit Lignite Mine

Abstract.  The generation of acid drainage from overburden spoil piles at open-pit lignite mines impacts water quality in large parts of the Lusatian mining area in Germany. The Lohsa Mine was exploited until the early 1990s and is to be flooded by 2005. It will then be used as a reservoir basin for the river Spree. Future acidity and sulphate concentrations in the surface water are of great interest because considerable amounts of the bank filtrate of the river are used to supply drinking water to communal water plants downstream. In our study, the input of sulphate from the unsaturated zone of the heap into the groundwater was calculated using the one dimensional reactive transport code SAPY. The SAPY program, which had been calibrated for effective diffusion and tortuosity using oxygen breakthrough curves of a column experiment with original heap sediments, was scaled up to field conditions and verified by measuring the oxygen and sulphate profile of the heap. Scenarios for a period of 80 years were simulated for different distances of the groundwater level to the subsurface, and the mass input of sulphate from the unsaturated zone into the groundwater was calculated in terms of specific fluxes for different times. Plans are to use the calculated source terms in a regional three-dimensional model to predict the evolution of the ground- and surface water in the area.     

Influence of organic amendments and arbuscular mycorrhizal inoculation on plant growth and nutrient uptake in iron ore mine spoils

Trema orientalis L. Blume is able to grow on nutrient-deficient soils and known to be a metal tolerant plant species displaying potential for use in mine restoration programmes. However, reclamation strategies would depend on the plant species used, and physico-chemical status of the spoil that often limits plant growth. This study was directed to determine the efficiency of arbuscular mycorrhizal (AM) species Rhizophagus irregularis and soil organic amendments (farm yard manure [FYM] and vermicompost [VC]), in enhancing growth and nutrient acquisition of T. orientalis in iron ore mine spoil (MS). A pot experiment was conducted using five treatments viz., AM, FYM, FYM and AM, VC, and VC and AM, with pure spoil as the control. Growth parameters, foliar nutrient concentrations and percentage AM root colonisation were determined at the end of 12?months. Addition of FYM and VC altered the chemical properties of spoil, increased pH and macro- and micro-nutrient levels and enhanced plant growth. Growth of T. orientalis was significantly increased by both organic amendments and by AM inoculation over control. AM colonisation increased plant survival in pure spoil and enhanced growth in both pure and amended spoil. High AM colonisation and plant dependency were recorded in pure MS and lower levels in amended spoil. AM colonisation plays a significant role in survival of T. orientalis in hostile iron ore MS environment. T. orientalis transplant success on iron ore mine sites would be greatly increased with VC and R. irregularis amendment.     

A Finite Element Model to: 2. Simulate Groundwater Rebound Problems in Backfilled Open Cut Mines

A two-dimensional finite element softwate called SEEP/W can be easily modified to simulate the groundwater rebound process within the spoil of an open cut mine taking into account saturated and unsaturated flow, hydraulic conductivity, and water content (as a function of pore-water pressure). Flexibility in the model is achieved by assigning different boundary conditions. In this paper, the results of the numerical model of the ground water rebound are presented and compared with those obtained from analytical solutions, another numerical model, and with data measured at the Horsley backfilled site in the UK. This model calculates realistic results that can be used by mine operators and environmental engineers to control the quality of mine drainage in a backfilled open cut operation.     

Hydrogeologic impacts in the Estonian oil shale deposit

The article describes the hydrogeological problems related to water influx to the mine and water sulphate content association with underground oil shale mining in an environmentally sensitive area of Estonia. The water balance method was used to calculate the ratio of mine water outflow/inflow. Water balance calculations are needed for estimating the groundwater transversal flow into closed mines. Before oil shale mining groundwater geochemical processes are characterised by low sulphate content. Dewatering of oil shale mines lowered groundwater level in the Keila–Kukruse aquifer, and caused an about 50-fold increase in sulphate by intensive oxidation of pyrite of natural origin. The mobile sulphate ion may serve as an indicator of changes occurring in the sulphate content of groundwater stored in the Keila–Kukruse and Lasnamäe–Kunda aquifers of the Ordovician system in the area of closed and working mines. Using the method of inverse mixing, sulphate ion distribution is a possibility to study the movement of groundwater in lateral and transversal directions.     

Fate of sulphate removed during the treatment of circumneutral mine water and acid mine drainage with coal fly ash: Modelling and experimental approach

The treatment of acid mine drainage (AMD) and circumneutral mine water (CMW) with South African coal fly ash (FA) provides a low cost and alternative technique for treating mine wastes waters. The sulphate concentration in AMD can be reduced significantly when AMD was treated with the FA to pH 9. On the other hand an insignificant amount of sulphate was removed when CMW (containing a very low concentration of Fe and Al) was treated using FA to pH 9. The levels of Fe and Al, and the final solution pH in the AMD–fly ash mixture played a significant role on the level of sulphate removal in contrast to CMW–fly ash mixtures. In this study, a modelling approach using PHREEQC geochemical modelling software was combined with AMD–fly ash and/or CMW–fly ash neutralization experiments in order to predict the mineral phases involved in sulphate removal. The effects of solution pH and Fe and Al concentration in mine water on sulphate were also investigated. The results obtained showed that sulphate, Fe, Al, Mg and Mn removal from AMD and/or CMW with fly ash is a function of solution pH. The presence of Fe and Al in AMD exhibited buffering characteristic leading to more lime leaching from FA into mine water, hence increasing the concentration of Ca²⁺. This resulted in increased removal of sulphate as CaSO₄·2H₂O. In addition the sulphate removal was enhanced through the precipitation as Fe and Al oxyhydroxysulphates (as shown by geochemical modelling) in AMD–fly ash system. The low concentration of Fe and Al in CMW resulted in sulphate removal depending mainly on CaSO₄·2H₂O. The results of this study would have implications on the design of treatment methods relevant for different mine waters.