Tesi sul tema "Coal Mining Waste Geomaterials"

Plus de 50 millions de tonnes de déchets miniers de charbon (CMWs) sont générées et stockées dans la nature chaque année en Pologne. Or, l'exposition de ces déchets aux conditions atmosphériques entraîne du drainage acide minier et la production de CO2. L'objectif de notre recherche est d'étudier la faisabilité d'utiliser les CMWs comme substitut aux granulats naturels dans le béton et le mortier. Notre étude porte à la fois sur la caractérisation des propriétés des CMWs et sur l'analyse des performances du béton / mortier à court et à long terme. L'effet de la teneur en CMWs sur la résistance à la compression, la résistance à la traction par fendage et la flexion, la densité du béton à l'état durci, l'absorption d'eau, la porosité et la durabilité ont été analysé. Il a été montré expérimentalement que la résistance du mortier diminue avec l'incorporation des sables miniers CMWS. Néanmoins, l'ajout des déchets n'affecte pas significativement l'ouvrabilité des mortiers à l'état frais. Les résultats expérimentaux ont également montré que les performances mécaniques des bétons incorporant les CMWs restent dans des limites acceptables pour des applications non structurelles. Les résistances à la compression, à la flexion et à la traction par fendage du béton ont déminué proportionnellement au taux et au type de substitution (sable ou gravillons). Les résultats des essais de durabilité des bétons incorporant des CMWs ont montré d'une part, une augmentation de la porosité et une réduction de la résistance à la compression, en particulier pour des taux élevés de substitution en gravillons CMWG sous le vieillissement du béton par des cycles de gel-dégel. D'autre part, les essais de pénétration des ions chlorure et de carbonatation ont montré une perméabilité accrue aux ions chlorure, et une plus grande profondeur de pénétration du CO₂, ce qui favorise la corrosion des armatures métalliques et réduit la durabilité des structures en béton armé. Cependant, la substitution de granulats CMW à faible pourcentage (moins de 30 %) limite la diffusion des chlorures et la pénétration de CO2 à un niveau comparable à celui des bétons ordinaires. Les analyses microstructurales (MEB/ EDX) et les analyses chimiques (FTIR) ont confirmé que l'incorporation de CMW entraîne une augmentation notable des pores et de leurs connectivités, ce qui facilite la pénétration de CO2 et Cl- dans la structure du béton. Enfin, il a été montré que la résistivité électrique présente un indicateur fiable des performances de durabilité des bétons incorporant des CMW. Une forte corrélation a été observée entre la résistivité électrique et la perméabilité aux ions chlorures et à la carbonatation
Over 50 millions tons per year of coal mine wastes (CMWs) are produced and stored in various locations in Poland. Exposure of these waste materials to atmospheric conditions leads to the formation of acid mine drainage and CO2 production. The objective of this research work is to study the feasibility of using CMWs as a substitute for natural aggregates in concrete and mortar, based on the characterization of coal mining waste properties, as well as the short-term and long-term properties of concrete/mortar. The effect of CMW content on compressive strength, splitting tensile strength, flexural strength, hardened density, water absorption, porosity, and durability was analyzed. It has been experimentally proven that mortar strength decreases with the incorporation of CMW sand. However, the addition of these waste materials does not significantly affect the workability of fresh mortars. The results also showed that the mechanical performance of concrete incorporating CMWs remains within acceptable limits for non-structural applications. The reduction in compressive, flexural, and splitting tensile strength is proportional to the substitution rate and type (sand or gravel). showed, on one hand, an increase in porosity and a reduction in compressive strength, especially for high substitution rates of CMWG gravel under freeze-thaw aging cycles. On the other hand, chloride ions penetration and carbonation tests showed increased chloride permeability and greater CO₂ penetration depth, which promotes the corrosion of steel reinforcement and reduces the durability of reinforced concrete structures. However, the use of CMW aggregates at low percentages (less than 30%) limits chloride diffusion to a level comparable to that of conventional concrete. Microstructural analyses (SEM/EDX) and chemical analyses (FTIR) confirmed that the incorporation of CMW leads to a significant increase in pore size and connectivity, which facilitates the penetration of CO₂ and Cl⁻ into the concrete structure. Additionally, it was shown that electrical resistivity is a reliable indicator of the durability performance of concrete incorporating CMW. A strong correlation was observed between electrical resistivity and permeability to chloride ions and carbonation

Modern coal preparation facilities incorporate a wide array of solid-solid and solid-liquid separation processes for rejecting mineral matter to meet market specifications. The coarse mineral matter is typically placed into engineered refuse piles whereas the fine refuse is either stored in impoundments or co-disposed with the coarse refuse. The discharge water from the refuse material represents an environmental concern due to the potential release of trace elements, and the subsequent elevation of total dissolved solids and conductivity. The research findings reported in this dissertation addresses sustainable coal processing waste disposal through using strategies aimed at minimizing the environmental impacts. To provide an accurate and inexpensive method to assess the potential environmental effects of a given waste material, a conductivity screening-level test was modified to incorporate the impact of particle surface area. The test was used on various waste streams as well as the particle size and density fractions of each waste stream to identify environmentally sensitive components that can be separated from the bulk and isolated to prevent negative environmental impacts. The results were subsequently evaluated for long term mobility of trace elements under different disposal scenarios: (i) static leaching tests designed to simulate the quiescent conditions in a stable impoundment, and (ii) a dynamic test to simulate waste materials exposed to the atmosphere in variable wet/dry storage conditions. The results indicated that liberating, separating and isolating the highest density fractions (>2.68 SG) which represents less than 5% of the coal refuse materials results in significant abatement of total dissolved solids and conductivity. Required modifications of the coal processing plants were suggested to segregate and subsequently isolate the environmentally sensitive fractions from the remaining refuse material.

The depletion of more attractive thicker and easily accessible coal seams in the central Appalachia will direct attention towards the extraction of coal seams thinner than 28 in. This thesis investigates the feasibility of an integrated mining and backfilling system applicable to thin seams. Two conceptual mining systems, namely Auger mining and Self Advancing Miner, have been proposed for this purpose. Both these systems are designed to remotely mine coal from the seams. Several attempts were made in the past to mine coal in a similar fashion but were not very successful due to several problems inherent to thin seams. The lack of effective steering techniques, accurate coal/rock interface and pillar thickness detection techniques were the main shortcomings of the systems. These problems were addressed in the proposed conceptual mining systems. Several coal/rock interface and rib thickness detection techniques currently available in the market or in the prototype stage have been discussed. Recent developments in coal/rock interface detection and direction sensing techniques have good potential in alleviating the previously encountered problems. Sensitivity analyses have been performed to assess the of effect critical mining parameters on the production potential of these systems. The self advancing miner has been found to be more promising than auger mining. Conceptual panels and face layouts for both systems have been included. Two types of filling methods namely pneumatic and hydraulic are considered applicable under thin seam conditions. A backfilling technique using rubber hoses for fill placement can be applied with both methods. Sensitivity analysis have been performed to establish the relationship between face operation cost, filling cost per ton and development cost per foot. Resulting analyses indicate that panel cost per short ton of coal is more sensitive to filling cost than on development cost.
Master of Science

A large percentage of Southern Appalachian coal reserves are located in seams less than 36" thick. As thicker and currently more mineable, deposits are exhausted, methods of underground thin-seam extraction will have to be developed. These methods must be capable of removing coal efficiently and economically. Past experience with highwall mining of thin-seam coal has indicated that recovery rates tend to be lower than in conventional operations. It is suspected that this will also apply to underground thin-seam mining, regardless of proposed technology or mining method. A method of increasing recoveries from thin-seam mining operations is necessary in order to exploit thin-seam reserves. Backfilling is one alternative that may find applicability in thin-seam coal mining. The ability of backfill to provide additional ground support may enhance coal recovery by allowing for the design of undersized pillars. Backfill has been used extensively in hard rock mining but has found limited use in coal mining. Its adaptability to thin-seam coal mining has been examined and is presented in this thesis. Backfill is capable of providing additional ground support by restricting lateral deformation of surrounding coal pillars and roof. This additional support can result in significant increases in recovery from thin-seam coal deposits. However, the overall feasibility of backfill is dependent on the in situ behavior of the fill material, the properties of the fill, the effects of the filling method on the total mining operation, and the cost of filling per extra ton of coal recovered. The influence of these parameters has been studied and indicate that, in certain situations, backfilling for the purpose of increasing recovery rates from thin-seam coal mines is feasible.
Master of Science

This thesis presents details of investigations into the potential for co-disposal of the two rejects from Clarence Colliery and Kable's Transport Sand Mine. Column experiments were undertaken to simulate field conditions. The experiment consisted of: 1/. creating the required co-disposal arrangement and structure in containers 2/. infiltrating water through each container and measuring the rates of infiltration and overflow 3/. measuring the chemical properties of the leachate water. Geotechnical tests of co-disposal pile stability were undertaken using a specially constructed shear box. Results of this study suggest the co-disposal of course coal washery reject from Clarence Colliery with clay tailings from Kable's Transport Sand Mine is a feasible option for managing the generation of acetic drainage. It is recommended that field trials comprise layers of coal reject and clay tailings in a 9:1 ratio. Layering the coal reject with clay tailings creates a semi-permeable barrier which acts to restrict water percolation through the reject as well as reacting with the leachate to increase the leachate pH and adsorb metals
Master of Engineering (Hons)

In this research, it is aimed to remove toxic heavy metals in waste water with the help of fly ash from Ç
ayirhan thermal power plant. The chemical and physical properties (size distribution, specific surface area, porosity, chemical composition, etc.) of fly ash were determined. The experiments were carried out in synthetic waste water containing lead, zinc and copper metals at different concentrations with the addition of fly ash. The effects of metal concentration, agitation time, particle size, ash amount, and pH in the metal removal were examined. With the addition of even very small amount of fly ash, heavy metal removal from waste water was attained at up to 99%. Fly ash particle size has no significant effect on removal of heavy metal ions from solutions. Higher solution pH and longer treatment time were resulted better metal removal. The results also indicated that the main mechanism for metal removal was precipitation due to alkaline characteristics of fly ash and more than 90 % of metals in solutions were removed by precipitation. The pH ranges for maximum metal precipitation were 10-11, 8-10, and 10-11 for copper, zinc, and lead respectively. Very small percentages of adsorbed metal was released during the desorption test.

This thesis presents details of investigations into the potential for co-disposal of the two rejects from Clarence Colliery and Kable's Transport Sand Mine. Column experiments were undertaken to simulate field conditions. The experiment consisted of: 1/. creating the required co-disposal arrangement and structure in containers 2/. infiltrating water through each container and measuring the rates of infiltration and overflow 3/. measuring the chemical properties of the leachate water. Geotechnical tests of co-disposal pile stability were undertaken using a specially constructed shear box. Results of this study suggest the co-disposal of course coal washery reject from Clarence Colliery with clay tailings from Kable's Transport Sand Mine is a feasible option for managing the generation of acetic drainage. It is recommended that field trials comprise layers of coal reject and clay tailings in a 9:1 ratio. Layering the coal reject with clay tailings creates a semi-permeable barrier which acts to restrict water percolation through the reject as well as reacting with the leachate to increase the leachate pH and adsorb metals

Coarse coal refuse is difficult to reclaim due to high potential acidity and coarse fragment content, low water holding capacity, low fertility, and other problems. Little is known about coal refuse properties, particularly as they relate to revegetation potential. This study was undertaken to determine the physical and chemical properties of composite samples from 27 coal waste piles of varying age. Selected physical and chemical properties varied widely across this sample set. The mean coarse fragment (>2mm) content of these materials was 60%. The average texture of the fine (<2mm) fraction was a sandy loam with 15% clay. The mean water retention difference, between 0.03 MPa and 1.5 MPa of soil moisture tension, on a whole sample basis was 0.08 g water/g refuse. The pH values varied from 8.3 to 3.0, and the older piles generally had lower pH values than the more recent piles. The saturated paste electrical conductivity (EC) was higher in the younger coal waste materials. Total elemental analysis revealed that Si, Al, Fe, and K were the most abundant elements in these materials. The mineralogy of three selected samples was found to be dominated by quartz in the sand and silt fraction and mica in the clay fraction. The physical factor most limiting to plant growth was found to be low water holding capacity. Low pH was found to be the chemical factor most limiting to plant survival. These findings indicate that some refuse piles may be suitable for direct seeding, but many will require heavy lime and/or organic treatments.
Master of Science

To assess strategies aimed at minimizing the release of trace elements and the impact of disposal of coal waste materials on the environment, two long-term leaching experiments of up to five months duration were performed using waste materials from two plants cleaning high and low sulfur bituminous coal. The tests evaluated the mobility of major trace elements under different disposal scenarios: (i) a static leaching test designed to simulate the quiescent conditions encountered by coal waste material stored under water in a stable impoundment, and (ii) a dynamic test to simulate waste materials exposed to the atmosphere, either in variable wet/dry storage conditions, or in unusual circumstances like those resulting from breaching of an impoundment containment wall. The results indicate that different refuse streams have different leaching characteristics due to difference in their mineralogy and the mobility of most elements is enhanced under highly alkaline or acidic conditions with a few being mobilized under both conditions, suggesting that the minimization of element mobility requires the pH value of the medium to be maintained around neutral. In addition, most of heavy metals were associated with the illite and pyrite minerals. Two strategies of treating coal refuse were evaluated: fly ash mixed with coarse refuse and co-disposal of coarse and fine refuse. Both methods were found to neutralize the pH conditions and thus reduce mobility of the trace elements in static leaching tests whereas the opposite was found from dynamic experiments. The results indicate that such controlled storage under water could retard acid generation and the mobility of trace elements.

Waste rock piles from coal mining of tertiary bituminous coal in Longyearbyen, Svalbard, show sulfide oxidation and subsequent acid mine drainage (AMD) production. The aim was to establish deeper understanding of AMD prediction based on Mineralogy and Geochemistry of coal and AMD samples. Mineralogical investigation of both coal and rock samples was performed with Automated SEM (ZEISS-Sigma VP300-Mineralogic System) as well as RAMAN. ICP-MS analysis was performed on solid and water samples. The pH from in situ measurements of AMD between 2,5-7,0. Eh varied from 222-569 mV (corresponding pe value of 3,7-9,6). This study showed that time of AMD in an oxidative environment was a key factor in iron concentration and iron speciation the AMD. This could not however be concluded in terms of age of mine site but rather the site-specific setting. The main minerals found in coal samples were pyrite (FeS2), siderite (FeCO3), calcite (CaCO3) and apatite (Ca5(PO4)3). Pyrites were identified with framboidal and euhedral textures and were found inside the maceral matter and in over- and underlying rocks respectively. SEM analysis of coal samples indicated that the modes of mineral formation was changing over the course of the Longyear seam. This study found that framboidal or euhedral textures of pyrite had different impacts in the AMD production. Framboidal pyrite was found to generate a greater amount of acidity than euhedral pyrites due to larger specific surface area and could therefore pose larger problems in AMD management.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998.
Trademark symbol follows Chemchar in title. Typescript. Vita. Includes bibliographical references (leaf 130). Also available on the Internet.

Estima-se que 60 a 70% do carvão ROM (run of mine) de Santa Catarina é descartado em módulos de rejeitos. Para mitigar o impacto ambiental decorrente deste armazenamento, cabe o manejo do rejeito integrando-o à paisagem através da implantação de cobertura vegetal. Neste sentido, este trabalho teve por objetivo propor a produção de solo a partir de rejeito de carvão mineral. Esse solo é passível de ser empregado na própria recuperação de áreas degradadas, evitando a extração de solo em áreas de empréstimo. O método consistiu na coleta e caracterização de rejeito de carvão (substrato), escórias e calcário (materiais alcalinos) e de lodo de estação de tratamento de esgoto (fonte de carbono orgânico, nitrogênio e fósforo). O rejeito foi beneficiado em meio denso para retirada de material carbonoso como flutuado na densidade de 2,2 e de material pirítico como afundado na densidade de 2,6; seguido de britagem e moagem para granulometria inferior a 2,0 mm. Escórias de aciaria, decorrentes da produção de aços especiais e aço ao carbono, foram britadas, moídas para granulometria inferior a 2,0 mm e utilizadas separadamente. O calcário já é comercializado abaixo de 2,0 mm não necessitando processamento extra. Lodo de ETE foi submetido a processo térmico, para desinfecção e secagem, destorroado também abaixo de 2,0 mm constituindo um biossólido. Adotou-se solo de área de empréstimo como material de controle. Estudos de crescimento vegetal foram conduzidos em um modelo experimental fatorial (dezesseis tratamentos implantados em triplicata): substrato principal (rejeito de carvão ou solo de área de empréstimo), misturado ou não a lodo de ETE, misturados ou não, separadamente, a três fontes de alcalinidade (escória de aço especial, escória de aços carbono e carbonato de cálcio). Os tratamentos com rejeito receberam cinzas de casca de arroz como condicionador físico. Os tratamentos foram dispostos em vasos, semeados com Avena strigosa (Aveia Preta), caracterizados e monitorados considerando-se parâmetros químicos (pH, macro e micro nutrientes), físicos (porosidade, densidade, capacidade de campo e condutividade elétrica) e ambientais (metais ambientalmente disponíveis). A Aveia Preta foi colhida próximo ao encerramento de seu ciclo. O material vegetal produzido foi pesado e analisado em termos de nutrientes e metais. Os resultados mostram que a mistura de rejeito da mineração de carvão (0,8% enxofre total) com a cinza de casca de arroz, concomitantemente a fonte de alcalinidade (escória ou calcário) e material orgânico (biossólido), resultou em um solo com propriedades químicas adequadas ao crescimento da Aveia Preta. Análises de tecido vegetal mostraram valores de macro e micronutrientes dentro dos padrões estabelecidos para esta espécie. A combinação rejeito de carvão dessulfurizado/cinza de casca de arroz/escória de aciaria/lodo configura-se como uma alternativa à disposição dos mesmos em módulos de rejeito e aterros. O uso de escórias de aciaria mostra-se uma alternativa viável ao calcário para neutralização de rejeito de carvão nas condições do experimento. Ainda que as escórias de aciaria, e em especial a escória de aço especial, tenham incluído cromo ao sistema solo-planta, as condições edáficas favoreceram o crescimento da Aveia Preta, denotando pouco efeito do mesmo no crescimento vegetal.
It is estimated that 60 to 70% of South Brazilian run of mine (ROM) coal is discharged into refuse piles as coal waste. In order to mitigate the environmental impact caused by storage, coal waste management is necessary through its integration into the landscape by the establishment of a vegetational cover. Because of this, the objective of this study was to propose the production of a soil from coal waste. This soil could be used in restoration itself, avoiding the extraction of soil from borrow areas. Methodology included sample collection and characterization of coal waste (main material), steel slag and agricultural lime (alkaline materials), and sewage sludge from a waste water treatment plant (organic carbon, nitrogen and phosphorous sources). Coal waste beneficiation used dense medium gravity separation to remove carbonaceous material that was floated at a density of 2.2 and pyritic material that sank at a density of 2.6, followed by blasting and milling to a particle size smaller than 2.0 mm. Steel slag derived, from special and carbon steel mills, were blasted, milled to particle size smaller than 2.0 mm and used separately. Commercial agricultural lime has a particle size smaller than 2.0 mm and did not need further processing. Sewage sludge from an urban waste water treatment plant was submitted to a thermal process for disinfection and drying, clods were broken to less than 2.0 mm rendering it into a biosolid. Soil from a borrow area was used as a control. Growth vegetation studies were conducted in a factorial delineation (sixteen treatments, all in triplicate): main substrate (coal waste or borrow area soil), main substrate mixed or unmixed with sewage sludge, than each combined with three sources of alkalinity (special steel slag, carbon steel slag and agricultural lime), or a non-alkaline treatment. Treatments composed of coal waste were mixed with rice husk ash to act as a physical soil amendment. All treatments were put in vessels and sown with Avena strigosa (Black Oat), characterized and monitored by chemical (pH, macro and micronutrients), physical (porosity, density, field capacity and electric conductivity), and environmental (readily available metals) parameters. Black Oat was harvested close to the end of its biological cycle. Plant tissue produced was weighed and analyzed for nutrients and metals. Results show that a mixture of coal waste (0.8% total sulfur) with rice husk ash combined concomitantly with a source of alkalinity (steel slag or agricultural lime) and organic material (biosolid) produced a fabricated soil with chemical properties adequate for the growth of Black Oat. Plant material showed that macro and micronutrient values were in agreement with standards established for this species. The combination - dessulfurized coal waste/rice husk ash/steel slag/sewage sludge could serve as an alternative to their disposal in refuse piles and landfills. The use of steel slag was shown to be a feasible alternative to agricultural lime to neutralize coal waste under these experimental conditions. Even though steel slag, especially special slag, added chromium to the soil-plant system, edafic conditions favored Black Oat growth which indicates a minor effect of the chromium present in the soils.

Дисертаційна робота присвячена дослідженням підтериконових стічних вод із породних відвалів вугільних шахт Нововолинського гірничопромислового району, аналізу системи заходів з метою підвищення екологічної безпеки гірничопромислового комплексу на довкілля. Встановлення рівнів екологічної небезпеки стічної води із відвалів вугільних шахт, дослідження сезонної динаміки вмісту важких металів стічної води з териконів, проектування та розрахунок біоплато дозволяють запровадити новітні форми очищення стічних вод із відвалів вугільних шахт та сприяють підвищенню екологічної безпеки регіону. У результаті проведених досліджень проб води зафіксовано підвищення вмісту солей амонію. Як відомо, головна небезпека забруднення гідросфери солями амонію полягає у перенасиченні води амоніаком. Вміст амонійних солей вище 0,1 мг/дм3 свідчить про свіже забруднення води, адже амоніак є першою сполукою, що утворюється в процесі розкладу органічних нітрогеновмісних речовин. Одночасний вміст у пробах води амоніаку, нітритів та нітратів, сульфатів, гідрокарбонатів свідчить про значну забрудненість підтериконових стічних вод через окиснення породи у відвалі та її вимивання водою. Підвищення в пробах води вмісту нітритів та нітратів без виявлення амоніаку свідчить про ізоляцію джерела забруднення. Аналізуючи стан екологічної ситуації в результаті розливання стічних вод з технологічних відвалів шахт №: 2, 4, 9 Нововолинського гірничопромислового району слід відмітити, що на даний час зливова каналізація на досліджуваних шахтах відсутня, тому дощові води із поверхонь породних відвалів та промислових майданчиків стихійно стікають у низовини на місцевості та концентруються мінеральними солями. Відомо, що для шахт цього району властиві значні водоприпливи в головні та підготовчі гірничі виробки, тому утворені стоки периметром існуючих відвалів збирають у водовідвідні канави. Встановлено причини та наслідки зростання рівня екологічної небезпеки угірничопромислових комплексах; сезонну динаміку вмісту хімічних речовин в підтериконових стічних водах із шахтних териконів; вміст важких металів у стічних водах та рослинності; запропонований науково обґрунтований розрахунок біологічних ставків для очищення стічних вод та заходи подолання негативного впливу техногенного забруднення стічних вод на біоту; за допомогою ГІС-проєкту “Open Environment” здійснено аналіз якості водних об’єктів досліджуваного регіону. Геоінформаційна інтерактивна карта побудована на базі статистичних даних Державного агентства водних ресурсів України та даних супутникових спостережень. Показники якості води підтверджують той факт, що поряд із вітровою ерозією териконів, дослідженню якої приділена велика кількість наукових робіт, гостро стоїть питання саме водної ерозії териконів, яка призводить до вимивання токсичних полютантів і забруднення ними ґрунту та підґрунтових вод. Забруднення поширюються із підтериконовими водами на значні відстані прилеглих територій, зокрема на поверхневі води басейну р. Західний Буг. Dissertation is dedicated to the research of wastewater from waste heaps of coal mines of Novovolynsk mining area, analysis of the measures system to increase the environmental safety of the mining complex. Establishing the levels of environmental hazard of wastewater from coal mine dumps, investigation of the seasonal dynamics of heavy metals content in wastewater from waste heaps, design and calculation of bioplates gives an opportunity to introduce the advanced technologies for treatment of wastewater from mine waste heaps and improve environmental safety of the region. As a result of water samples analysis, an increase in the content of ammonium saltswas determined. It is known that the main danger of pollution of the hydrosphere with ammonium salts is the supersaturation of water with ammonia. The content of ammonium salts above 0.1 mg/dm3 indicates the water pollution, because ammonia is the first compound formed during the decomposition of organic nitrogen-containing substances. Simultaneous occurrence of ammonia, nitrites and nitrates, sulfates, bicarbonates in the water samples indicates a significant contamination of wastewater due to oxidation of the rock in the dump and its leaching with water. An increase of nitrites and nitrates content in water samples without ammonia indicates the isolation of the source of contamination. Analyzing the ecological situation as a result of spillage of wastewater from dumps of mines №: 2, 4, 9 of Novovolynsk mining area it should be noted that currently storm sewer system is absent there, so rainwater from the surfaces of waste heaps and industrial sites spontaneously drain in lowlands and concentrates by mineral salts. It is known that the mines of this area are characterized by significant inflows into the main and preparatory mine workings, so the formed effluents around the perimeter of the existing dumps are collected in water diversion channels. The causes and consequences of the growth of environmental hazard level in mining complexes, seasonal dynamics of the chemicals content in wastewater from mine heaps, heavy metals content in wastewater and vegetation were established; scientifically substantiated calculation of biological ponds for wastewater treatment and measures to overcome the negative impact of man-made wastewater pollution on biota were suggested; by applying the GIS project "Open Environment" the analysis of the water body quality of the area was carried out. The geoinformation interactive map is built on the basis of statistical data of the State Agency of Water Resources of Ukraine and data of satellite observations. Water quality indicators confirm the fact that besides the wind erosion of waste heaps, the water erosion of waste heaps is of a high concern, which leads to leaching of toxic pollutants into soil and groundwater. Pollution spreads with wastewaters over long distances of adjacent territories, in particular to the surface waters of the Western Bug basin

M.Sc. (Geography)
Coal mined in South Africa for the competitive international market, has to be selected to meet the many quality specifications of customers. This upgrading is done by washing the coal in a heavy medium separation plant. Marketable coal, discard and slurry are produced from this washing. Discard consists mainly of poor quality coal, carbonaceous shale and waste rock. Iron pyrite (FeS2) occurs in all of the above in higher concentrations than in the marketable coal. Both the carbonaceous materials and pyrites generate heat when oxidizing. If this oxidation is not arrested at an early stage on a discard dump and the temperature of the dump increases above BOoC, spontaneous combustion is quite likely. The South African Council for Scientific and Industrial Research (CSIR) has estimated that smouldering discard dumps in the Eastern Transvaal highveld region contribute approximately 400 000 tons of S02 per annum to the atmospheric pollution in that area. As a result, significant localized acid rain occurs, Louw (1990). The oxidation of iron pyrites to sulphuric acid, and the oxidation of other trace elements, is accelerated under the high temperature conditions generated by spontaneous combustion. Leaching of these oxidation products results in local groundwater and surface water contamination. This study describes different disposal technique and pilot study aimed at minimising the oxidation within the dumps. Slurry, which consists of discard and/or coal of less than 1 mm in diameter is co-deposited with discard in sequential layers of approximately 200 mm thick. This has resulted in reducing the permeability, porosity and air and water exchange within the dump. This in turn has led to a reduction in spontaneous combustion, pollution and costs. A visual increase in stability of the discard dumps, moisture content and operational ease of placement were experienced. The saleable value of the dump as a low value heat source is also preserved.

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, for the Degree of Master of Science.
storage and waste dumps from coal mining tend to spontaneously combust. This is mainly as a result of the oxidation process which is accelerated by the availability of oxygen and the exothermic nature of the oxidation process. In cases of poor ventilation the heat accumulation within the bed is thought to lead to the spontaneous combustion of coal. The work in this dissertation aims to investigate the change in oxygen concentration in a bed of coal and also measure the rate of oxidation (oxygen absorption) in a closed reactor under isothermal conditions. Drying rate of coal under nitrogen was also looked into. An analysis of the oxygen concentration profile in a three metre 20 cm ID plastic column filled up with coal has been carried out. As the coal ages (becomes oxidised) its reactivity towards oxygen decreases and changes in the oxygen concentration profile are noticed. Experiments have been carried out up to 8 months and from the results obtained, a simple pseudo-steady-state model has been developed to describe the diffusion of oxygen into a reacting coal bed. The findings could prove useful in trying to find a solution to coal and waste dump fire control. The second experiment is a simple isothermal oxygen absorption experiment in which the rate of absorption of oxygen on a given coal sample is measured at different initial concentrations of oxygen. The initial concentration of oxygen is varied over a fairly wide range in order to determine the dependence of the rate of oxidation on the oxygen concentration. The rate- limiting step in low temperature oxidation of coal is found to be the absorption of oxygen. Moisture also plays a role in coal oxidation. Drying experiments were also carried out so as to quantify and investigate the rate of loss of moisture. Models have been developed which try to explain the mechanisms involved in the drying process. The modelling suggest that the bound water model is more appropriate to the type of behaviour exhibited during the drying process
Andrew Chakane 2018

A project report submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg in partial fulfilment of the requirements for the degree of Master of Science in Engineering Johannesburg, 1993
Superfines of less than 200 micron are generated when mining coal. They have not been successfully beneficiated in the past and are not acceptable to the consumer. A processh as been developed whereby the superfines are beneficiated, briquetted without the use of binders and devolatilised to produce a premium smokeless briquette which will attract a premium price in the export market. [Abbreviated abstract. Open document to view full version]
MT2017

Waste rocks (WRs) from coal mining and fly ash (FA) from coal combustion were studied to determine the potential of the WRs to generate AMD, FAs to neutralise it and estimate their impacts on environment. The ultimate goal was to develop a methodology based on co-disposal to mitigate the environmental problems associated to both wastes. Two methods for co-disposal were tested: i) Mixing WRs and FAs and ii) covering WRs with FAs. WRs were sampled from the Lakhra coal mines in Pakistan (PK), which has an estimated coal reserves of 1.3 Btonne, varying from lignite to sub-bituminous quality. The FA was sampled from a power plant utilising coal from Lakhra coal mines and is situated in close vicinity (15km) of the mine site. For comparative purposes a bituminous FA from Finland (FI) and biomass FA from Sweden (SE) were also characterised. The WRs and FA samples were characterised by mineralogical and geochemical methods. Besides organic material (coal traces), quartz, pyrite, kaolinite, hematite, gypsum and traces of calcite, lime, malladerite, spangolite, franklinite and birnessite were identified in WRs by XRD. The major elements Si, Al, Ca and Fe were in the range (wt. %) of 8 – 12, 6 – 9, 0.3 – 3 and 1 – 10, respectively, with high S concentrations (1.94 – 11.33 wt. %) in WRs. The AMD potential of WRs ranged from -70 to -492 kg CaCO3 tonne-1. All FAs contained quartz, with iron oxide, anhydrite and magnesioferrite in PK, mullite and lime in FI and calcite and anorthite in SE. The Ca content in SE was 6 and 8 times higher compared to PK and FI, respectively. FAs were enriched in As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn compared to continental crust. The acid neutralising potential of PK was equivalent to 20 kg CaCO3 tonne-1 compared to 275 kg CaCO3 tonne-1 (SE) and 25 kg CaCO3 tonne-1 (FI). During the period of 192 days in weathering cell experiments (WCE), the pH of leachates from most acidic WRs was maintained from 1 to 2.5, whereas, the less acidic WRs produced leachates of mildly acidic (2.7) to neutral (7.3) pH. The leachates from very acidic WRs ranged in the concentrations of Fe, SO24− and Al from mg L-1 to g L-1. The samples were subjected to column leaching experiments (CLE) in which mixture (FA:WR; 1:3) and cover (FA:WR; 1:5) cases were mimicked (with 10mm particle size) and effects of particle size (2, 5 and 10mm) on element leaching were studied. Despite having the lowest acid-neutralisation potential compared to FI and SE, co-disposal of PKFA as mixture readily provides acid buffering minerals, resulting in better start-up pH conditions and leachate quality. However, acidity produced by secondary mineralisation contributes towards the acidification of the system, causing stabilisation of pH at around 4.5−5. Secondary mineralisation (especially Fe- and Al-mineral precipitation) also removes toxic elements such as As, Pb, Cu, Zn, Cd, Co, Ni and Mn, and these secondary minerals can also buffer acidity when the pH tends to be acidic. In contrast, the pH of the leachates from the PKFA cover scenario gradually increased from strongly acidic to mildly acidic and circumneutral along with decrease in EC and elemental leaching in different WRs. Gradually increasing pH can be attributed to the cover effect, which reduces oxygen ingress, thus sulphide oxidation, causing pH to elevate. Due to the fact that pH~4–5 is sufficient for secondary Fe- and Al-mineral precipitation which also removes toxic elements (such as Cd, Co, Cu, Zn and Ni) by adsorption and/or co-precipitation, the FA cover performs well enough to achieve that pH until the conclusion of the CLE. However, due to the slower reactivity of the buffering system (additional to the initial flush-out), leaching in the beginning could not be restricted. The co-disposal of FA as cover and/or mixture possesses potential for neutralisation of AMD and improving leachate quality significantly. Particle size of the WRs affected the leaching of the sulphide related elements (such as Fe, S, Zn, Co, Cr, Cu, Mn and Ni) in CLE and WCE. Experiments with ≤1mm particle size constantly produced acidic and metal laden leachates. Co-disposal of FA and WRs as cover and mixture need to be investigated on pilot-scales before full-scale application.

Seepage from steelmaking coal mine waste rock dumps in the Elk Valley, British Columbia, Canada can contain selenium (Se), cadmium (Cd), and sulfate (SO42-) from the oxidation of sulfide minerals, and nitrate (NO3-) from blasting. The impact of these constituents of interest (CIs) on receiving groundwater systems and the potential for their natural attenuation is investigated. A 10.7 km2 mine-impacted research catchment (West Line Creek) was instrumented with 13 monitoring wells and 8 drivepoint wells to characterize the hydraulics and geochemistry of the aquifer system downgradient of the waste rock dump. These data were augmented with geophysical surveys and by characterizing the lithology, geotechnical properties, and geochemistry of core samples obtained during drilling. Furthermore, the groundwater monitoring program also facilitated the development of a conceptual model of hydrogeology in a small montane valley. An unconfined aquifer at the overburden/fractured bedrock interface, i.e. the basal alluvial aquifer was identified as the primary groundwater conduit for the migration of water and solutes from the waste rock dump toward Line Creek. Vertical and horizontal dispersion of CIs was confirmed with porewater analysis of core samples, with Se concentrations exceeding the BC water quality guideline (2.0 µg/L) in 98% of samples (n = 223). Residence time for groundwater in the overburden aquifers was determined using 3H/3He age dating (n = 3) and estimates of groundwater velocity to be less than three years across the 650 m study site. The chemistry of groundwater was compared with rock drain water samples to evaluate CIs from their source through to identified discharge locations. Linear correlation of CI concentrations with SO42- concentrations in water samples showed that Se and NO3- were conservative solutes, whereas Cd was non-conservative and may be undergoing mineral precipitation or adsorption reactions in the groundwater system. The distribution of CIs in the overburden aquifers was seasonally variable and dilution was determined to be the dominant mechanism controlling the concentrations of conservative CIs (Se, SO42- and NO3-) away from the toe of the waste rock dump and during the spring freshet. The basal alluvial aquifer downgradient of the waste rock dump was estimated to annually discharge 16% of the water and 7% of the SO42- load from the catchment.

MESMEG
Department of Mining and Environmental Geology
The Mushithe coal occurrence is situated approximately 16 km west of the Tshikondeni coal mine in the Tshipise-Pafuri sub-basin of the Soutpansberg coalfield in South Africa. The Soutpansberg Coalfield has received comparatively less attention compared to other more notable South African coalfields. There is as a consequence very limited information in the public domain applicable to the geology as well as quality of coal in this coalfield, as a result there is no known study focused exclusively on the Mushithe coal occurrence. The aim of the study was to conduct detailed geological mapping of the Mushithe Deposit so as to ascertain the geological environment and petrological characteristics of rocks within the area. Further work involved coal sampling and analysis in order to establish coal quality and its physical and chemical characteristics. Samples were collected using geological field mapping and channel sampling. Nine coal samples were collected from the coalbed and host rock, exposed along the Mbodi River, during geological field mapping using channel sampling. Furthermore, 92 rock samples were collected during geological field mapping of which 10 representative samples were selected for further analysis. X-ray fluorescence spectrometry was conducted on all selected samples. Proximate analysis and ultimate analyses, and calorimetry tests were undertaken on coal samples. Three samples were selected based on calorific value for maceral identification, mineral analyses and vitrinite reflectance using petrographic study. Detailed geological mapping of the area around the Mushithe coal occurrence showed the geological setting of coal in this area. The following lithologies were identified in the study area: sandstone, mudstone, ironstone, calcrete, shale, quartzite, quartz vein with a general strike direction to the north-east. The host rocks including coal were intruded by dolerite dykes and this resulted in the devolatilization of coal. The current study concluded that the Mushithe coal was formed in a wet swampy environment. This has been confirmed based on tissue preservation index (1.69) and gelification index (2.35). Coal rank ranged from bituminous Rank C- B according to United Nations Economic Commission for Europe Coal Classification (UNECE) and samples were characterised by high ash (27.90%), high moisture (10.47%) and low sulphur (0.24%). Furthermore, coal was graded below grade D based on classification for use by ESKOM which consider any calorific value below 24.5 MJ/kg to be in this category. The coal is vitrinite rich (77.75 vol%) and low in Inertinite (22.25 vol%) and devoid of Liptinite and pseudovitrinite, thus it is of good coking quality. Geochemical analysis revealed that the coal was enriched in TiO2 and Fe2O3 which was corroborated by the mineral matter which was mostly clay and pyrite. Comparatively, coal quality analysis revealed the calorific value of 14.26 MJ/kg and vitrinite reflectance between 0.94 %ROV to 1 %ROV which was less than that of the Tshikondeni Deposit but greater than that at Waterberg coalfield. The study recommends further detailed exploration of coal in the area, applying such techniques such as geophysical exploration and borehole drilling leading to resource evaluation. Further studies are recommended to provide a better interpretation of the depositional environment of coal at Mushithe as well as the effect of devolatilaziton by a dolerite dyke.
NRF

Coal seams are commonly associated with poor quality water that requires treatment. Water treatment can be very expensive and can severely affect the profitability of mining projects. This study investigated the potential cultivation of Arthrospira maxima (Spirulina) in coal seam water to beneficiate coal seam water in order to effectively offset the water treatment cost. The study was conducted in Northern South Africa and formed part of a larger Coal Seam Water Beneficiation Project (CSWBP). The study consisted of laboratory based Flask Studies and outdoor High Rate Algal Pond Studies. The Flask Studies that were carried out in the on-site field laboratory, found that the coal seam water could provide a suitable medium for Spirulina cultivation. In addition, it was found that the optimal pH for the selected strain ranged between 9 - 10.5 and that the addition of excess iron, up to 100 times the concentration found in defined growth media such as Schlösser’s, to the culture media could enhance productivity. The High Rate Algal Pond Studies (HRAP) were carried out over a period of 18 months. The studies showed that the coal seam water at the CSWBP is a valuable resource that can reduce media costs by 50% without affecting productivity. In a study encompassing 334 days it was shown that heating the culture through plate heat exchangers would result in a significant increase in productivity and a heated productivity of 19.86 g/m2/day was recorded. An unheated productivity of 14.11 g/m2/day was recorded. Therefore, it was found that it would be economically feasible to beneficiate coal seam water found at the CSWBP through the cultivation of Arthrospira maxima (Spirulina).
Environmental Sciences
M. Sc. (Environmental Science)