Coal Washing Process Research Articles

Sustainable bioleaching of heavy metals from coal tailings using Bacillus inaquosorum B.4: Mechanistic insights and environmental implications

Coal tailings are byproducts of the coal washing process and pose significant environmental pollution issues due to the release of heavy metal elements. In this study, a sustainable bioleaching method was proposed, and a Bacillus inaquosorum B.4 strain with high Extracellular Polymeric Substances(EPS) production characteristics was isolated through mutagenesis. The importance of EPS in the adsorption of free heavy metals was validated, as EPS-covered (EPS-C) cells exhibited significantly higher removal rates of Cu (71.30 ± 1.10 %), Pb (79.90 ± 1.02 %), and Zn (64.90 ± 1.00 %) compared to EPS-removed (EPS-R) cells. The adsorption kinetics followed pseudo-second-order kinetics models. The significant bioleaching efficiency of this strain for heavy metals Pb, Zn, and Cu in coal tailings was investigated. Through shake flask experiments under conditions of a particle size of 45–74 μm, pH of 7, and a bacterial concentration of 15.00 %, the bioleaching rates of Pb, Zn, and Cu were found to be 91.88 mg/kg、23.21 mg/kg、8.06 mg/kg, respectively. The B.4 strain's mechanism of action was determined using techniques like SEM, XRD, FT-IR, and LA-ICP-MS. It involves absorbing organic compounds, disrupting the lattice structure of heavy metal minerals, and releasing metal ions. These metal ions are then immobilized by forming complexes with functional groups on the bacterial surface. The bioleaching process was primarily subject to a combination of chemical reaction and diffusion control. This research offers a practical bioremediation strategy to manage heavy metals in coal tailings and has important implications for environmental protection and sustainable resource utilization.

High-strength geopolymer concrete based on coal washing waste

In recent years, geopolymers have gained significant attention as an environmental-friendly alternative to Ordinary Portland Cement (OPC). Geo-Polymer Concrete (GPC) can be made using different aluminosilicate sources but using waste aluminosilicate sources not only helps to reduce environmental pollution, also leads to efficient waste management. Coal Washing Waste (CWW) refers to the waste that remains after coal washing process in the purification plants. CWW (if properly activated) can be used as a high potential aluminosilicate source to produce GPC or a supplementary cementitious material in the production of Blended Cement (BC). Hence, this study aims to investigate the use of CWW as a waste aluminosilicate source for manufacturing GPC. In this regard, CWW subjected to various methods of thermal activation and the obtained ash was used to produce GPC specimens. Thereafter, the mechanical and physical properties of CWW based-GPC were studied and also compared with conventional concrete. Furthermore, CWW ash was used as an OPC partial replacement (15 %) for BC production. The obtained results indicated that thermal activation conditions of CWW have a significant effect on the properties of the obtained CWW ash. Rapid and abrupt cooling of ash after heat treatment resulted in higher pozzolanic reactivity and thus higher compressive strength. Moreover, CWW ash-based GPC offers higher mechanical strengths, as well as excellent resistance to acidic conditions and low water absorption capacity. Furthermore, CWW ash-based GPC provides proper resistance to evaluated temperatures so that it is almost stable up to 800 °C.

Application of a water injection hydrocyclone on fine coal enhanced gravity separation

ABSTRACT This study introduced Krebs hydrocyclone into fine coal EGS process, examined the ultrafine classification effect of Krebs hydrocyclone by single-factor tests and orthogonal tests, and evaluated the fine coal EGS effect after ultrafine classification. Besides, the flow field characteristics in Krebs hydrocyclone were explored by simulation. The optimal grading efficiency of the verification test is 91.32%, and the content of ultrafine particles can be reduced to 1.01%, which prove the excellent ultrafine classification effect of Krebs hydrocyclone. The optimal combustible recovery and ash removal rate are 94.29% and 98.52%, respectively, and when the clean coal ash drops below 10%, the combustible recovery is more than 80%, which reveal that the sorting indexes of fine coal EGS after ultrafine classification are much better than that of unclassified coal. Both the static pressure and velocity in Krebs hydrocyclone have good symmetry and certain regularity. Due to the use of water as a separation medium, the introduction of Krebs hydrocyclone in the fine coal EGS process provides an effective and prospective approach for the industrial application of enhanced gravity separators in the fine coal washing process, especially in the face of increasingly serious environmental problems.

Fully automated coal quality control using digital twin material tracking and statistical model predictive control for yield optimization during production of semi soft coking- and power station coal

The quality control of a two-stage coal washing process involves several complex components that need to be modelled accurately, to enable autonomous control of the process. The first objective is to develop a method to track the material through the washing process, while ensuring accurate washing prediction models are used. This was achieved through a digital twin model of the Grootegeluk 1 coal processing plant. The model is the amalgamation of manipulating and combining of data-sets from the plant historian, geological wash tables, and mining dispatch servers. This information is then used to control and set the processing medium densities of all 15 modules on the plant, 10 modules in the primary wash and 5 modules in the secondary wash. This controller has been successfully implemented and controlled the plant for 10 days.

Migration behaviors of arsenic and sulfur from coal during washing process and their release characteristics during combustion process

Two raw coals and their washery products were collected from two coal-washing plants of Ningwu coal field, Shanxi, China. The migration behaviors of sulfur (S) and arsenic (As) during coal washing process were investigated by the microwave digestion method together with hydride generation-atomic fluorescence spectrometry. Based on the checked mass balance of As, a sequential-chemical-extraction method was used to explore the dependence between speciation transformation and release characteristics of S and As during the combustion process of raw coal, cleaned coal, coal gangue, middling coal, or coal slime. The results show that 20%–28% of S and As in raw coal are migrated to the cleaned coal, and 46%–61% of them to gangue. Pearson correlation coefficient identifies that the inorganic minerals in samples control the migration behavior of S and As. Compared with the elements in raw coal, the proportions of organic S and As in cleaned coal increase to 30%–50%, while the inorganic S and As in coal gangue account for more than 90%, which indicates the dependence between the species of S and As in raw coal and its washery products. The relatively large amount of organic S and As in the cleaned coal obviously release together with water and volatile matters below 500 ℃. While the inorganic bonded As and S in gangue mainly release during the decomposition process of pyrite, sulfate and other inorganic minerals between 500 and 1000 ℃, which shows the consistency of S and As release characteristics during combustion of raw coal or washery product. The release rates of S and As from the cleaned coal are the fastest among all samples and the corresponding maximum release ratios are 80%–95% at 300 s and 60%–75% at 200 s, respectively, whilst their release rates from gangue are the slowest and As reaches the maximum release ratio of 40%–45% at 300 s but S doesn’t get to the maximum release ratio even at 600 s. The release rates of S and As from the middling coal or raw coal are between the cleaned coal and gangue. The different release rates of S and As during the sample combustion are mainly depended on their speciation distributions in nature.

Effects of Chemical Properties and Inherent Mineral Matters on Pyrolysis Kinetics of Low-Rank Coals

The kinetics during the pyrolysis process depend on both chemical structure and inherent mineral matters in coal, but normally, only one of these components is investigated in literature. In the present work, four low-rank coals were pyrolyzed in a thermogravimetric analyzer at a heating rate of 10 K/min in a constant nitrogen stream at a temperature up to 900 °C to study the pyrolysis behavior and kinetics. Two of the samples were raw coal (R-YL) and clean coal (C-YL) obtained through the washing process. The results showed that the coal-washing process mainly affected the inorganic part (mineral matters) and structure in coal, which did not largely change the chemical properties. The pyrolysis behavior in primary stage (before 550 °C) was mainly affected by the chemical properties of coal, while the pyrolysis behavior in higher temperature also depended on inherent mineral matters. The kinetics of four coals were obtained using the Coats–Redfern (CR) method with five theoretical models. The difference of E value was almost negligible for R-YL and C-YL, also showing that the coal-washing process did not largely change the chemical properties. The higher frequency factor A for clean coal C-YL showed a more porous structure due to the coal-washing process. The apparent activation energy E in the third stage was affected by the thermodynamic property of inherent minerals.

Analysis of CO2 Emissions in the Whole Production Process of Coal-Fired Power Plant

The linear programming (LP) model has been used to identify a cost-effective strategy for reducing CO2 emissions in power plants considering coal washing, pollutant removal, and carbon capture processes, thus CO2 emissions in different production processes can be obtained. The direct emissions (combustion emissions and desulfurization emissions) and indirect emissions (pollutant removal, coal washing, and carbon capture) of CO2 were all considered in the LP model. Three planning periods were set with different CO2 emission control desirability to simulate CO2 emissions of the different reduction requirements. The results can reflect the CO2 emissions across the whole production process of a coal-fired power plant overall. The simulation results showed that for a coal-fired power plant containing two 1000 MW ultra super-critical sets, when the desirability was 0.9, the CO2 total emissions were 2.15, 1.84, and 1.59 million tons for the three planning periods. The research results suggest that the methodology of LP combined with fuzzy desirability function is applicable to represent the whole production process of industry sectors such as coal-fired power plants. The government policy makers could predict CO2 emissions by this method and use the results as a reference to conduct effective industrial and energy structure adjustment.

Эффективность обогащения угля и функция желательности Харрингтона

The technological efficiency of the coal washing process is traditionally assessed by the correlation between the practically achieved results of this coal washing at a coal dressing plant and the theoretically possible ones defined by the laboratory testing to define the coal washability. However, the laboratory assessment of coal washability is a labor-intensive process and cannot be used for on-line control. The article considers the possibility of introducing a performance evaluation indicator using parameters traditionally defined in operational control schemes. This indicator is based on the well-known function of qualitative process evaluation based on several parameters, i.e. the Harrington's desirability function. The proposed efficiency indicator was calculated based on the qualitative and quantitative parameters of washing thirty different coals using the conventional processing scheme. Evaluation of the proposed efficiency indicator was made by comparing it with the traditionally used efficiency indicators. The evaluation results showed that the proposed indicator is more informative, because it also allows to take into account the compliance of the ash content during washing with the specified parameter, as well as to evaluate the efficiency of the washing process more objectively than the traditionally used clean coal yield indicator. Within a given ash content of the clean coal there exists a correlation with the performance indicators recommended for assessment of the washing efficiency. Given the specific features of the desirability function, the indicator makes it possible to qualitatively assess the coal washing process and determine the optimal value..

Effects of coal slime on the slurry ability of a semi-coke water slurry

As a by-product of the coal washing process, the methods involving the resource utilization of coal slime are very few because of its strong agglomeration and large water content. In this work, we propose a new way to dispose of coal slime, which involves preparing semi-coke water slurry (SCWS) with coal slime. When using sodium humate as dispersant at a dosage of 0.8wt%, the solid concentration of ordinary SCWS reached a maximum (63.8wt%) , and the concentration improved to 65.3wt% after adding 15wt% coal slime, and the calorific value of the slurry (18.07MJ/kg) that can meet the Chinese standard (GB/T 18855–2002). The role of coal slime in improving the ability of SCWS is to optimize the particle size distribution as a small size material; additionally, it can improve the hydrophilicity of particulates through oxygen-containing groups and minerals, which increased the performance of SCWS.

Selective Removal of Sodium from Low-Rank Xinjiang Coal upon Multistage Countercurrent Water Washing: Experimental Investigation and Kinetics Modeling

Prior washing of coal is an essential step for the minimization of ash-related slagging and fouling inside a coal-fired boiler. With regard to the coal washing process, the recyclability of the washing reagent, usually water, is critical from both cost-effective and efficiency perspectives. This paper addresses the washing kinetics of water-soluble Na+ from two different low-rank Xinjiang coals using both fresh and used/recycled water to alleviate the ash-related fouling in low-rank coal-fired boilers. Apart from once-through fresh water washing, washing using recycled water via both multicycle single-stage and three-stage countercurrent processes was studied in detail to investigate the recyclability of water. Additionally, a modified shrinking core model (SCM) was developed to reveal the Na+ removal mechanism under all washing conditions. Our experimental results showed that the Na+ removal extent decreased with the recycling of used water due to an increase in the Na+ concentration in the recycled water and/or a decrease in the Na+ content in the washed coal. The saturation point of Na+ in the used water, beyond which the water can no longer remove Na+, is far below the solubility of NaCl in water. The modeling approach further confirmed that the overall rate for the removal of water-soluble Na+ is dominated by the intraparticle diffusion within the coal matrix. The effective diffusion coefficient of Na+ was within the range of 0.28 × 10–6 to 3.75 × 10–6 cm2/s, which agrees with reported values in the literature. Additionally, a novel iterative calculation method integrating the modified SCM into the three-stage countercurrent washing process has been proposed to predict the Na+ removal at each stage for each cycle. The results show that the water can be recycled a maximum of 15 times in the three-stage countercurrent process.

The role of gangue on the mitigation of mining-induced hazards and environmental pollution: An experimental investigation

Gangue, produced from coal mining and washing process, is a serious threat to the ground environment. Gangue backfilling mining method can solve this problem and reduce mining-induced hazards, e.g., controlling surface subsidence and preventing water inrush from seeping into goaf by cracks in overlying strata. In this paper, effects of the original particle size distribution (PSD) and water content on the particle crushing behavior and seepage properties of granular gangues were investigated. Experimental results show that the crushing behavior can promote the compaction of gangue particles; the variation of PSD after crushing reveals distinct fractal characteristics. With the increasing compression stress, the particle crushing ratio and fractal dimension increase, while the permeability decreases. Due to the rearrangement of particles and newly generated fine particles filled the gap among larger particles, it is difficult to reduce the permeability by increasing the compressive stress. In addition, the variation of fractal dimensions is similar to the crushing ratio, so the particle crushing can be illustrated by fractal dimensions. The relationship between porosity and permeability established by the Kozeny-Carman equation can model the effect of particle crushing in this research. The reliability of the equation is verified by the comparison of model result and experimental data. To increase the mitigation rate of mining-induced hazards and environmental pollution by GBM method, granular gangues can be crushed into smaller particles and dehydrated before backfilling.

Aprovechamiento de un residuo del carbón para reducción del impacto ambiental de la minería del carbón en Colombia: estudio del potencial de uso en la industria del cemento

Con el propósito de reducir la emisión de CO2 en la producción de cemento, incrementar el aprovechamiento de residuos y generar materias primas alternativas con mayor disponibilidad y potencial de uso, se han venido estudiando nuevos materiales capaces de desarrollar propiedades cementicias, especialmente residuos industriales, que permiten disminuir el consumo de clínker en el cemento. Adicionalmente, se conoce que la minería del carbón genera gran cantidad de residuos o estériles, tanto en la explotación como en el beneficio. Por tanto, en este trabajo se estudió el desempeño mecánico y la resistencia a la compresión de una matriz de cemento adicionada con un residuo del carbón colombiano activado térmicamente, generado específicamente del proceso de lavado del carbón, con el propósito de poder utilizar este residuo como material cementante suplementario. La caracterización físico-química y mineralógica del material en estado natural y calcinado, se llevó a cabo mediante granulometría por hidrómetro, FRX, DRX, ATG/ATD y análisis próximos del carbón. El residuo está compuesto en su mayoría por SiO2, Al2O3, SO3 y Fe2O3, y sus fases mineralógicas principales son cuarzo, caolinita e illita. Se evaluó la resistencia mecánica a la compresión de morteros con 20% de sustitución y se encontraron resultados óptimos al comparar con la muestra control a 28 y 90 días de curado.

Studies on mercury occurrence in inorganic constituents of Polish coking coals

During the cokemaking process, a significant amount of mercury occurring in a coal blend is released to the atmosphere. One of the ways of reducing this emission is to reduce mercury content in a coal blend. This could be obtained through the coal washing process. The optimization of this process requires the knowledge of mercury occurrence in coal, especially in its inorganic constituents. A qualitative analysis of mercury occurrence in the inorganic constituents of Polish coking coals was performed using an electron probe microanalyzer (EPMA). For that purpose, selected samples of rejects and middling products derived from the washing process in dense media separators and jig concentrators were examined. The obtained results have confirmed a strong connection between mercury occurrence and the presence of sulfides (pyrite, marcasite, and chalcopyrite) in Polish coking coals. Significant amounts of mercury were also noticed for barite, siderite, and aluminosilicates. The highest value of mercury content, at the level of 0.100%, was obtained for marcasite. For the analyzed coals, the effectiveness of mercury removal in the washing process was determined by the forms of pyrite occurring in coal. The highest values of effectiveness of mercury removal were obtained in the case of coals for which the large framboidal pyrite aggregates with chalcopyrite overgrowths were noticed. It was also found that middling products were characterized by the occurrence of the Hg-rich overgrowths of pyrite on organic matter. To achieve a significant reduction in mercury content in clean coal, it is necessary to develop an effective method of removing this form of pyrite from hard coal.

Preliminary assessment of the possibility of mercury removal from hard coal with the use of air concentrating tables

Abstract Mercury is characterized by highly toxic properties. The natural biogeochemical cycle of mercury occurs in the environment, which results in the fact that even a small amount of mercury emitted to the environment is a potential threat to human health. The process of coal combustion is one of the main sources of anthropogenic mercury emissions. For this reason, on 31 July 2017 the European Commission has adopted the mercury emission standards for large combustion plants. The issue of mercury emissions is particularly important for Poland. Forecasts concerning energy consumption in Poland show that coal will be the main source for energy production in the coming decades. Therefore, actions enabling the reduction of mercury emissions from coal-fired power plants will have to be implemented. The mercury emissions from coal-fired power plants may be reduced through the application of a number of methods. These methods can be divided into two main groups: the post-combustion methods which allow for mercury removal from flue gases, and the pre-combustion methods which allow for mercury removal from coal before its combustion. The effectiveness of mercury removal from coal is determined by the mode of its occurrence in coal. In the case of mercury occurrence in the adventitious inorganic constituents of coal, high effectiveness will be obtained in the coal cleaning processes. In the case of mercury occurrence in the organic matter as well as in the inherent inorganic constituents of coal, the effectiveness of this method will be low. Mercury could be removed from such coals through the process of thermal pretreatment at the temperature of 200-400°C (mild pyrolysis). In the paper, the possibility of mercury removal from hard coal through the process of dry deshaling on an air concentrating table was examined. Six raw coals (coal feed), clean coals and the rejects derived from their dry deshaling were analyzed. The mercury content was measured in the examined samples. The content of mercury in raw coals and clean coals were compared. Additionally, the effectiveness of mercury removal from coal with rejects was determined. For the analyzed coals, the effectiveness of mercury removal from coal in the process of dry deshaling on an air concentrating table ranged from 9 to 96%. This effectiveness is similar to the effectiveness of mercury removal from coal in the processes of coal washing. It should be mentioned that, when compared to the coal washing processes, the dry deshaling process is characterized by lower investment and operating costs. Therefore, the dry deshaling process on an air concentrating table should be considered as a competitive method for the coal washing processes. There is also a possibility of an increase in the mercury removal efficiency from coal in the process of dry deshaling as a result of the thermal pretreatment of clean coal derived from dry deshaling. This solution is only recommended for coals in which mercury occurs in the organic matter as well as in the inorganic constituents characterized by a relatively low temperature of mercury release.It should be emphasized that the dry deshaling process allowed for a decrease of mercury content is not suitable for every coal. Although for five of the analyzed coals the mercury content in clean coal was lower in the range from 11 to 53%, for one coal the mercury content was higher by 19%. The effect of decreasing the mercury content in coal is more evident when it is related to the amount of energy contained in coal (i.e. for example to the lower heating value). For five of the analyzed coals mercury content expressed in such a way decreased in the range from 11 to 53 %, and for one coal the mercury content was, however, higher. Nevertheless, the difference was not very significant (ca. 5%).

Selective removal of sodium and calcium from low-rank coal – Process integration, simulation and techno-economic evaluation

This paper has addressed the techno-economic feasibility regarding the selective removal of sodium (Na) and calcium (Ca) from low-rank sub-bituminous coal, aiming to reduce the ash slagging and fouling propensity in the pulverized coal-fired boilers. Four novel process integrations were proposed and simulated in Aspen Plus. Both the novel counter-current three-stage water washing process and an acid-water two-stage washing process have proven to improve the ash fusion temperature satisfactorily, reducing the mass fraction of Na2O in ash from 4.32wt% to 0.85 and 0.19wt%, respectively. In addition, the use of acid-water washing removed 12.5% CaO and 19.5wt% total ash. For the recycle and treatment of wastewater, the water gain is desirable for the use of an evaporator, owing to the dewatering of the initially high-moisture coal (25wt%) in the centrifugal and the high water recovery rate from the evaporator. However, the good performance of evaporator was counteracted by the considerable capital cost caused by the huge heat transfer area requirement. Instead, the use of reverse osmosis (RO) resulted in a water loss up to 228.4kg/t coal. Additionally, prior to the RO treatment unit, the recycle and reuse of the unsaturated water for maximum six times and four times for three-stage water washing and acid-water two-stage washing, respectively, was critical in reducing both the water and power consumption. The water consumption dropped to 38.1kg/t coal and 48.1kg/t coal for the three-stage water washing and acid-water two-stage washing process, respectively. Both are remarkably lower than 85.0kg-water/t black coal. In terms of the power consumption, it decreased to ~9.4kWh/t coal for the three-stage water washing process and further down to 5.8kWh/t for the acid-water washing case, which was even slightly lower than 6.3kWh/t for the black coal. Furthermore, the integration of acid-water washing and RO was also demonstrated to be economically viable by its high NPV, IRR and short payback period. Sensitivity analysis indicate that, the original Na content in raw coal is the most influential variable on the water and power consumption of the overall process, followed by the initial moisture content in the raw coal. For a low-rank coal containing >2150–2520ppm Na and/or <19wt% moisture, the washing process proposed would turn economically unviable compared to the existing black coal washing process. A minimum selling price of 136 RMB/t (−32% deviation) was also necessary to keep both NPV and IRR positive as well as the payback period shorter than the project lifetime.

A Dual-Loop Control System for Dense Medium Coal Washing Processes With Sampled and Delayed Measurements

A dual closed-loop control system is developed for a dense medium coal washing process. The controller is designed to improve the separation efficiency and energy efficiency of the dense medium cyclone coal beneficiation process simultaneously making use of a model predictive control method and a pumped-storage system (PSS). In the dual-loop control, the outer loop is designed for medium density profile optimization and the inner loop is used for actuator control of the medium supplying circuit, considering the interplay of the energy efficiency and separation efficiency. Mathematical models of the PSS and the magnetite recycle process of the dense medium circuit are developed and employed in the design of the advanced controller. The effectiveness of the designed control system is demonstrated by simulations based on operational data from a South African coal beneficiation plant.

Characterisation of coal washery effluent and optimisation of coagulation behaviour of Moringa oleifera seed as a coagulant

The huge quantity of effluent generated in coal washing processes contains large amount of suspended and dissolved solids, clay minerals, coal fines and other impurities associated with raw coal. The present system of recirculation of the effluent is found to be ineffective in removing colloidal fines, which is the major part of the impurities present in washery effluent. Hence, there is a need for the assessment of a better technique for an efficient removal of these impurities. This study deals with detailed characterisation of coal washery effluent and fine particles present in it. For efficient removal of impurities, the suitability of biocoag-flocculation process using Moringa oleifera seed biomass as a natural coagulant was examined. Various doses of M. oleifera ranging from 0.2 to 3mL/L were used in order to determine the optimal conditions. The impact of the variations in pH of the effluent (2-10), contact time (5-30min), settlement time (5-50min), temperature (10-50°C) and the effluent dilution (1:0-1:5) was also assessed to optimise the treatment process. Post treatment analysis was carried out for determination of the different parameters such as pH, conductivity, turbidity, solids and settling velocity. Excellent reduction in turbidity (97.42%) and suspended solids (97.78%) was observed at an optimum dose of M. oleifera seed coagulant of 0.8mL/L with an optimum contact time of 15 and at 20min of settling time. In comparison with very few past studies of M. oleifera in the treatment of coal washery effluent with high dose and inadequate removal, this study stands to be a major highlight with low dose and high removal of the impurities. M. oleifera coagulant is considered to be an environment-friendly material, therefore, its application is recommended for simple and efficient treatment of coal washery effluent.

SEPARATION OF MINERAL MATTER FROM INDIAN COAL BY USING SOLVENTS

Coal resources have been estimated at over 861 billion tone globally. India accounts for 236 billion tonne of coal. Coal meets around 30.3 % of global primary energy needs and generates 42% of the world’s electricity. Indian electricity capacity has a rapid growth from 1350MW in the year 1947 to more than 140,000MW presently. Wide spectrum of coal is required ranging from power generation to steel production, infrastructure and commercial purposes. Indian coals contain high in ash content ranging from 15% to 55% [1] but low in sulphur content. Power plants complain of high ash content, inconsistent quality and size. Research and process development to produce the ash-free coal (Hyper-coal, HPC) has been carrying out since 1999 [5]. To improve the quality of coal by washing to reduce the environmental impact, enhance coal quality and increase process efficiency. Coal washing and coal beneficiation processes are the major thrust in terms of developing strong research cells for developing better practices, suiting requirements of all the coalfields of India. The extraction yield depends strongly on the coal particle size, solvent and extraction conditions. Experimental investigation for removal of mineral matter from Indian coal by using three different solvents such as Tetrahydrofuran, 1,4 Dioxane and Diethyl ether. Comparative study on reduction of ash content of Indian coals having different average particle sizes(0.126mm,0.258mm and 0.403mm) using different solvents reveals that Tetrahydrofuran is the best solvent with respect to these used solvents. The maximum reduction of ash content is found to be 23.16%. Experimental studies also highlighted how ash removal of coal by using solvents is increased with the decrease of particle size due to the easy liberation of ash bearing components from coal particles [16].

Coagulation Experimental Study of Coal Washing Wastewater Treatment

Coal washing wastewater is the end of the wet coal mine coal washing process industrial water , which contains a lot of slime and silt , causing serious pollution to the environment of the mine near this study, coagulation treatment of coal washing wastewater to determine the best flocculants and optimum operating parameters : agitation intensity 90r/min, polyaluminum chloride (30mg / l) dosage of 10ml the polyacrylamide dosage 3ml , pH = 7-11 . The treated effluent can be reused , either to protect the environment , but also save water resources .

Experimental Research on Hybrid Strategy and Desulfurization for White Mud and Coal Slurry

White mud is a kind of solid waste from the papermaking process, because of the high pH value and desulfurization material, it can be used as a desulfurization agent. Coal slury is the waste from the coal washing process and generally be used as fuel. This paper studies the hybrid method for white mud and coal slurry to be transported by pipeline, and the furnace desulfurization effect with the mixture. Rheological properties of coal slury and white mud was analyzed, and then based on the rheological data the coal slurry, white mud and water mixed strategy was obtained. By altering calcium sulfur ratio and operation parameters of boiler, fluidizing bed boiler desulphurization effect was tested with the mixture, the economic analysis was also performed through comparision of operational cost. The result shows that the proposed hybrid method is not only relatively simple, but also has the characteristics of good desulfurization effect, high desulfurization efficiency, and good economy. The study has important guiding meaning for desulphurization of coal slurry fluidized bed boiler.