Research progress and prospects of coal petrology and coal quality in China

Clean utilization of coal depends on the quality of raw coal,which depends on the coal-forming parent materials(petrology and chemical composition of coal),the multiple media of the coal-forming environment,and some epigenetic conditions,such as thermal evolution(coalification),magmatic hydrothermal fluid,groundwater.Based on the research results of predecessors and prediction studies of coal resources since the founding of China,the present status of research on coal petrology,coal quality,coal metamorphism,and coal geochemistry in China is discussed in detail,with emphasis on research progress and the general situation of highly efficient and clean utilization of coal in the technical fields of coking,pyrolysis,combustion,gasification,and liquefaction,and the development prospects of coal petrology and coal quality in China are prospected.

Progress in Researches on Evaluation of Quality of Cultivated Land Consolidated from Coal Mining Subsided Land

The evaluation of consolidated cultivated land quality can provide basic information for how to perfect the program of land consolidation,as well as a reference for the dynamic monitoring of farmland quality in mining area. Based on the consultation and analysis of related literature,we can conclude that: firstly,most scholars focus on soil consolidation,while consider little about land use and economic condition. Secondly,foreign scholars usually use crop yields to judge the success of land consolidation,while domestic scholars have been evaluated the quality of consolidated cultivated land synthetically from several aspects,such as soil fertility,soil environmental quality,and farmland infrastructure conditions. Specifically,most of the evaluations are static,and indicators are different. Besides,the quality of consolidated cultivated land is generally low,and it lacks systematic research on technologies for improving quality of cultivated land consolidated from coal mining subsided land. It is concluded that future researches should focus on establishing scientific and feasible evaluation system to realize comparison of quality change in the dynamic course of " undisturbed-subsided-consolidated" cultivated land in coal mining areas,as well as technologies for improving quality of cultivated land consolidated from coal mining subsided land.

The Technical Analysis on Upgrade and Coupling of Low-Quality Coal

Experimental study was conducted with regard to upgrading low-quality coal by low temperature pyrolysis technology and fluidization classification technology, which laid the theoretical foundation for research and development of low-quality coal upgrading process. Firstly, a pyrolysis pilot experiment of long-flame coal was performed and the optimum pyrolysis conditions were found. When the final pyrolysis temperature was 450?C and the residence time was 10 minutes, the content of semicoke volatile dry ash-free was about 22.89% and the content of semicoke ash was about 16.1%. More than 5% of the ash needs to be removed before entering the pyrolysis fluidized bed. Thus, classification tests were carried out to pick out the coal particles with the target size of 500 μm, using a gas-solid fluidized bed coal picker. It was found that the separating effect of coal particles was the most satisfactory when the inlet velocity at the bottom was 3.27 m/s. The percentage of particles with diameters less than 500 μm was as low as 28.7% in the coarse samples. Based on the test results, a novel process of low-quality coal upgrade and coupling was proposed, which realized the sorting, grading, drying and pyrolysis of low-quality coal through the multi-stage fluidized bed integrated process.

Calcium and Lead Levels in the Biological Samples and Their Effect on the Biochemical Parameters of Indoor and Outdoor Workers of Five Zonal Areas of Coal Mining Field

Workers of the Lakhra coal mining Sindh Pakistan were affected by a multi-factorial exposure of heavy metals. The prevalence of lead (Pb) exposures in work-related symptoms among workers of indoor and outdoor mining of Lakhra coal mining was evaluated in detail. The biological samples (scalp hair and blood) of 270 workers of Lakhra coal mining {official and control subjects} (indoor and outdoor) 18 to 55 years age group and 70 referent subjects of same age-groups were examined. The biological samples (blood and scalp hair) of workers of Lakhra coal mining and referent subjects were analyzed for calcium (Ca) and lead (Pb). Flame atomic absorption spectrometry was applied for the determination of the Ca in digested samples of studied subjects by the microwave oven whereas, the Pb contents were measured by electrothermal atomic absorption spectrometry. The validity of the methodology was checked by using the certified human hair material (BCR 397) and lyophilized human blood (Clincheck). The results indicated the higher contents of Pb in biological samples of indoor and outdoor mining workers than referents. However, the levels of Ca were found to be lower in indoor and outdoor mining workers than those of referents. It can be concluded that immediate action should be taken by recommended authorities to improve the ventilation and hygiene practices inside the industries, mines, and other workplaces.

Establishing a Relationship between Coal Quality and the Enrichment of Radionuclides in Coal Combustion Residues

Coal-fired power plants (CFPP) provide approximately 40% of the world’s energy demand. Naturally occurring radioactive materials (NORM) contained in coal become enriched in coal combustion residues as a result of the elimination of carbon during combustion. The fly ash and bottom ash produced from CFPP may be significant sources of exposure to naturally occurring radionuclides for the population near the combustion plant or ash dumps. Despite this fact, very few studies have actually addressed the relationship of the NORM enrichment factors and the quality of coal used. This paper aims to relate the quality of coal to the enrichment factors for the radionuclides of interest (K40, Ra226, Th232 and Po210) in coal combustion residues from three South African CFPP. The data from other CFPP was also taken into account to establish this correlation. The feedstock coal used in these CFPP is typically low quality, with ash content in the range of 25 - 45 wt%. The radionuclides investigated were determined by gamma spectrometry with the exception of Po210, which was determined by alpha spectrometry. The enrichment factors for the radionuclides of K40, Ra226, Th232 and Po210 in the fly ash and bottom ash (except Po210) was found to be directly proportional to the quality of coal. That is when the ash percentage increased (coal quality decreased) the enrichment factor decreased. The Po210 radionuclide in the bottom ash had an enrichment factor less than one. The relationship between coal quality and enrichment factors for the radionuclides of K40, Ra226, Th232 and Po210 in both the fly ash and bottom ash (except Po210 in the bottom ash) was demonstrated by the following mathematical equation: . This equation may be used as a good indication in obtaining an estimate in determining the enrichment of the mentioned radionuclides in coal combustion products such as fly ash and bottom ash.

Study on Model for Assessment of Quality Management Performance of Coal Preparation Plant in CIMS

In this paper the method to calculate intangible quality cost is put forward for the first time based on the production and management characteristics of coal preparation plant. A model for assessment of quality management performance of coal preparation plant is established on the ground of quality cost. By using of CIMS integration environment the strategy to carry out the model and the application example are also offered. It provides a new and feasible way to assess performance quality management of coal preparation plant.

RESEARCH ON THE QUALITY PRICE RATIO OF COKING COAL

If assortment priee parity of Clase coking coal and its qtalty price danrcnee is nonreasonable, it deren’t gulde in Anprotrig tbe quallry metaliurgical coking coal and may be influence theeconomic benefit of metallurgical enterprises. This paper propose the principles and mathematicmodel for determination aseortment party of clean cokingcoal and its quality difference of ash content in clean coking coal in order to urge wasbenes into producing superior clean coking cleal whichis under condition of consideration both interest waskeries and interest metallurgicai industry. It canbe used as a method in theory to make price strategies under condition of socialism maket economicfor washeries of clean coking

THE OPTIMUM MODEL AND ITS DECISION SUPPORT SYSTEM OF COAL QUALITY BALANCE

The meaning and significance of coal quality balance are summaized in this paper.Practical steps concerning constructing the synthetic tech-economic model and its decision support system of coal quality balance using the optimization techology of inverse recurrence of established initializing parameters are also introduced. The principles and methods as being applied in the model system development and procedure construction are discussed accordingly.

Thermo-chemical conversion of coal samples under high temperature

Exhaustion of profitable coal resources makes for need of innovation including underground coal gasification(UCG).One of the most important problems of UCG is evaluation of the combustion area in underground coal seams.Physicochemical parameters of coal,in a whole,and coal mineral substance are changed under heating and combusting.Thermo-chemical conversion of coal mineral components has an effect on magnetic characteristics of coal seam and can be used for real-time control of combusting area.To this guessing check laboratory experiments have been made as an activity of the Far Eastern Federal University.Our investigation based on a theoretical analysis and laboratory simulation tests.Typical results of the laboratory experiments are presented below.Under heating coal thermo-chemical magnetization is forming.Coal's magnetic parameters varieties from anti-ferromagnetiсto ferromagnetic.Anti-ferromagnetic pyrite and siderite presented into coal mass is transformed into magnetic hematite and magnetite under heating.Therefore,geomagnetic is expected to be a useful geophysical tool to for evaluation of combustion volume and its migration for underground coal gasification.

Spatial analysis and evaluation of a coal deposit by coupling AHP & GIS techniques

Nowadays,the evaluation of coal deposits becomes crucial,due to many uncontrollable factors,which affect the energy sector.A comparative evaluation of coal deposits is essential for their hierarchical classification regarding their sustainable exploitation,when compared to other coal deposits or competitive fuels,which may be used as alternative solutions for electricity generation.In this paper,a method for spatial analysis and evaluation of a lignite deposit is proposed,by creating four spatial key indicators via GIS analysis,which are then aggregated by applying a weighted linear combination.The analytical hierarchy process is applied to estimate the relative weights of the indicators,in order to perform a weighted cartographic overlay.Through the synthesis of the indicators,an overall,total spatial quality indicator is calculated.The weighted analysis was shown to be more effective compared to the unweighted one,because it can provide more reliable results regarding the exploitation of the examined lignite deposit.The implementation of GIS-based analytical hierarchy process in spatial analysis and evaluation of lignite deposits,in terms of sustainable exploitation,demonstrates that this method can be extensively applied for evaluating the economic potential of mineral deposits.

Floor dust erosion during early stages of coal dust explosion development

An ignition of methane and air can generate enough air flow to raise mixtures of combustible coal and rock dust.The expanding high temperature combustion products ignite the suspended dust mixture and will continue to propagate following the available combustible fuel supply.If the concentration of the dispersed rock dust is sufficient,the flame will stop propagating.Large-scale explosion tests were conducted within the National Institute for Occupational Safety and Health(NIOSH)Lake Lynn Experimental Mine(LLEM)to measure the dynamic pressure history and the post-explosion dust scour depth.The aim of this effort is to provide quantitative data on depth of dust removal during the early stages of explosion development and its relationship to the depth of floor dust collected for assessing the incombustible content most likely to participate in the combustion process.This experimental work on dust removal on is not only important for coal mine safety but also for industrial dust explosions.

Bayesian discriminant analysis for prediction of coal and gas outbursts and application

Based on the principle of Bayesian discriminant analysis, we established a model of Bayesian discriminant analysis for predicting coal and gas outbursts. We selected five major indices which affect outbursts, i.e., initial speed of methane diffusion, a consistent coal coefficient, gas pressure, destructive style of coal and mining depth, as discriminating factors of the model. In our model, we divided the type of coal and gas outbursts into four grades regarded as four normal populations. We then obtained the corresponding discriminant functions through training a set of data from engineering examples as learning samples and evaluated their criteria by a back substitution method to verify the optimal properties of the model. Finally, we applied the model to the prediction of coal and gas outbursts in the Yunnan Enhong Mine. Our results coincided completely with the actual situation. These results show that a model of Bayesian discriminant analysis has excellent recognition performance, high prediction accuracy and a low error rate and is an effective method to predict coal and gas outbursts.

A general solution and approximation for the diffusion of gas in a spherical coal sample

The square root relationship of gas release in the early stage of desorption is widely used to provide a simple and fast estimation of the lost gas in coal mines. However, questions arise as to how the relationship was theoretically derived, what are the assumptions and applicable conditions and how large the error will be. In this paper, the analytical solutions of gas concentration and fractional gas loss for the diffusion of gas in a spherical coal sample were given with detailed mathematical derivations based on the diffusion equation. The analytical solutions were approximated in case of small values of time and the error analyses associated with the approximation were also undertaken. The results indicate that the square root relationship of gas release is the first term of the approximation, and care must be taken in using the square root relationship as a significant error might be introduced with increase in the lost time and decrease in effective diameter of a spherical coal sample.

GC/MS Analysis of Fractional Extraction of Fusain from Tongting Bituminous Coal in CS_2

Fusain from Tongting (Huaibei, Anhui Province) bituminous (FTTB) coal was fractionally extracted using Soxhlet extractor with CS2. Then the extracts were analyzed with GC/MS. Comparison of experimental data between FTTB coal and clarain from Tongting bituminous (CTTB) coal was carried out. The results show that the kinds of small molecule components detected by GC/MS of FTTB are less than those of CTTB. Long-chain alkanes exist mostly in the extracts of fusain. Macromolecular networks are predominant in the FTTB coal mainly composed of inertinite in the coal petrography. The size of micropores in the FTTB coal is relatively small, and the development of micropores is relatively low. Thus the content of aromatic compounds with affinity for micropores is relative low in FTTB, while the content of long-chain alkanes with affinity for macromolecule networks is relatively high. Sub-components in exinite determine the distribution of long-chain alkanes extracted in the last stage. Odd-numbered carbon distribution appears when resin is most in exinite, while high carbon alkane distribution appears when exinite is dominant in cutinite. Small aromatic molecules are firstly packed in micropores, and exist in a free state after micropores are saturated.

Porosity Analysis Based on CT Images of Coal Under Uniaxial Loading

According to the character of CT image, surface porosity and voxel porosity are defined from pixel and voxel scale respectively. Digital Terrain Model (DTM) method is applied to calculate the surface porosity, and the method of voxel porosity is also presented based on Industrial CT grey image. With proposed methods, CT images of coal under differ-ent uniaxial loading are analyzed, and the relation curves between two kinds of porosity and stress separately are shown. All of these porosities reflect inner damage of coal. The surface porosity shows the pore with pixel scale, and voxel porosity denotes the pore inner pixel. The voxel porosity reflects the character of CT image better.

Characteristics of water contamination in abandoned coal mines:a case study on Yudong River area,Kaili,Guizhou Province,China

The seasonal and spatial changes in the chemical composition of the water in abandoned mine drainages and rivers in Yudong River area in the years of 2017-2018 were analyzed.The effects of mine water drainage on the seasonality and physicochemical properties of the river water after mine closure were evaluated,and the feasibility of irrigation using river water and the degree of pollution to farmland were assessed using the Water Quality Standard for Farmland Irrigation.The results show that the mine water has low pH value(<3.5-4)and high levels of total hardness,SO_(4)^(2−),Fe,Al,and Zn.In addition,the pH of the mine water is negatively correlated with the presence of other metal ions.The correlation coefficient between the chemical oxygen demand(COD)and Fe reached 0.989.While the pollution levels of Pinglu and Baishui rivers were low,the confluence region of the two rivers was seriously polluted.However,only the levels of Fe and Cd slightly exceeded the Surface Water Environmental Quality Standard after the confluence of Yudong and Chongan rivers.Overall,the heavy pollution type of the confluent river is consistent with mine water pollution.The water quality is slightly better in the dry season compared than in the high-water period.Sulfate and Fe content decreased by 39 and 16 mg/L,respectively,and Cd content decreased two-fold.Despite these findings,this study shows that from 2017 to 2018,the pH and Cd content of the rivers at the confluence exceeded the irrigation limit and the water quality continued to deteriorate,which may pose a soil contamination risk.Long-term use of the river for irrigation water may cause toxic elements such as Cd,Fe,Mn,SO_(4)^(2−),Al,and F-to enter the food chain,thereby endangering the life and health of villagers in Yudong River area.

Study on Generation Cost Prediction Based on Coal Quality and Generating Unit Performance

燃料变化条件下发电成本的预测是火电厂普遍关心的重要课题。分析了影响机组性能及发电电量成本的各种煤质指标，重点研究了基于结构参数及燃烧传热机理的锅炉稳态热力性能分析计算方法，讨论了制粉系统、风机、脱硫和脱硝装置性能随燃料等运行条件的变化关系，最终提出了基于煤质和机组性能分析计算的发电电量成本预测模型并研发了“煤炭选配与机组发电成本预测系统”。该系统在我国某600MW火电厂的实际应用经验表明：提出的电量成本分析预测模型合理，研发的软件系统有助于辅助火电厂的选煤和购煤决策，优化动力配煤方案，从而提高火电厂的运行经济性。