Structural properties of residual carbon in coal gasification fine slag and their influence on flotation separation and resource utilization:A review

Coal gasification fine slag(FS)is a typical solid waste generated in coal gasification.Its current disposal methods of stockpil-ing and landfilling have caused serious soil and ecological hazards.Separation recovery and the high-value utilization of residual carbon(RC)in FS are the keys to realizing the win-win situation of the coal chemical industry in terms of economic and environmental benefits.The structural properties,such as pore,surface functional group,and microcrystalline structures,of RC in FS(FS-RC)not only affect the flotation recovery efficiency of FS-RC but also form the basis for the high-value utilization of FS-RC.In this paper,the characteristics of FS-RC in terms of pore structure,surface functional groups,and microcrystalline structure are sorted out in accordance with gasification type and FS particle size.The reasons for the formation of the special structural properties of FS-RC are analyzed,and their influence on the flotation separation and high-value utilization of FS-RC is summarized.Separation methods based on the pore structural characterist-ics of FS-RC,such as ultrasonic pretreatment-pore-blocking flotation and pore breaking-flocculation flotation,are proposed to be the key development technologies for improving FS-RC recovery in the future.The design of low-cost,low-dose collectors containing polar bonds based on the surface and microcrystalline structures of FS-RC is proposed to be an important breakthrough point for strengthening the flotation efficiency of FS-RC in the future.The high-value utilization of FS should be based on the physicochemical structural proper-ties of FS-RC and should focus on the environmental impact of hazardous elements and the recyclability of chemical waste liquid to es-tablish an environmentally friendly utilization method.This review is of great theoretical importance for the comprehensive understand-ing of the unique structural properties of FS-RC,the breakthrough of the technological bottleneck in the efficient flotation separation of FS,and the expansion of the field of the high value-added utilization of FS-RC.

Characteristics of coal resources in China and statistical analysis and preventive measures for coal mine accidents

In the process of green and smart mine construction under the context of carbon neutrality,China's coal safety situation has been continuously improved in recent years.In order to recognize the development of coal production in China and prepare for future monitoring and prevention of safety incidents,this study mainly elaborated on the basic situation of coal resources and national mining accidents over the past five years(2017-2021),from four dimensions(accident level,type,region,and time),and then proposed the preventive measures based on accident statistical laws.The results show that the storage of coal resources has obvious geographic characteristics,mainly concentrated in the Midwest,with coal resources in Shanxi and Shaanxi accounting for about 49.4%.The proportion of coal consumption has dropped from 70.2%to 56%between 2011 and 2021,but still accounts for more than half of the all.Meanwhile,the accident-prone areas are positively correlated with the amount of coal production.Among different levels of coal mine accidents,general accidents had the highest number of accidents and deaths,with 692 accidents and 783 deaths,accounting for 87.6%and 54.64%respectively.The frequency of roof,gas,and transportation accidents is relatively high,and the number of single fatalities caused by gas accidents is the largest,about 4.18.In terms of geographical distribution of accidents,the safety situation in Shanxi Province is the most severe.From the time distribution of coal mine accidents,the accidents mainly occurred in July and August,and rarely occurred in February and December.Finally,the"4+4"safety management model is proposed,combining the statistical results with coal production in China.Based on the existing health and safety management systems,the manage-ments are divided into four sub-categories,and more specific measures are suggested.

Fluidized mining and in-situ transformation of deep underground coal resources: a novel approach to ensuring safe, environmentally friendly, low-carbon, and clean utilisation

Traditional coal mining and utilisation patterns are severely detrimental to natural resources and environments and significantly impede safe, low-carbon, clean, and sustainable utilisation of coal resources. Based on the idea of in situ fluidized coal mining that aims to transform solid coal into liquid or gas and transports the fluidized resources to the ground to ensure safe mining and low-carbon and clean utilisation, in this study, we report on a novel in situ unmanned automatic mining method. This includes a flexible, earthworm-like unmanned automatic mining machine (UAMM) and a coal mine layout for in situ fluidized coal mining suitable for the UAMM. The technological and economic advantages and the carbon emission reduction of the UAMM-based in situ fluidized mining in contrast to traditional mining technologies are evaluated as well. The development trends and possible challenges to this design are also discussed. It is estimated that the proposed method costs approximately 49% of traditional coal mining costs. The UAMM-based in situ fluidized mining and transformation method will reduce CO2 emissions by at least 94.9% compared to traditional coal mining and utilisation methods. The proposed approach is expected to achieve safe and environmentally friendly coal mining as well as lowcarbon and clean utilisation of coal.

Effect of coal resources development and compensation for damage to cultivated land in mining areas

The exploitation of coal resources inevitably affects, to different degrees, arable land resources and impacts the socio-economic development in mining areas. Therefore it is of great practical importance to probe the rules of the effect from coal resource exploration on arable land. Suitable and effective measures to compensate for damaged to and loss of arable land resources should be taken on the basis of carrying out green mining and reducing damage to limited arable land resources. We have used GIS in simulating the effect of coal resource exploration on arable land. In light of our simulation of the space-time spectrum, the effect is analyzed. Given the socio-economic development conditions of a mining area, specified rational amounts and opportunities for compensation to arable land in mining areas are explored. Finally, from a policy perspective, relevant proposals for rational arable land resource compensation are proposed to facilitate the coordinated development between coal resource exploitation and socio-economy development in mining areas.

Several Economic Problems for Extraction of Coal Resources

There exist both economic problems and environmental problems in the development and utilization of coal resource. A mathematical model is introduced by which the maximal profit of coal enterprise can be obtained. The first order necessary conditions and second order necessary conditions to solve the mathematical model are offered. In addition, by use of coal price model with the property of transcendental logarithm optimal production rate and mine lift are proposed in this paper. Several factors that effect net profit of coal enterprises are analyzed.

The two-factor model of evaluating mining rights of coal resources based on options

MRCR could be regarded as a multi-stage compounding real option,based on option theory,assuming the convenience yield of coal reserves to be constant,built a one-factor model of valuating MRCR with the stochastic value of coal reserves.On the basis of our one-factor model,set up a two-factor model of evaluating MRCR assuming the convenience yield follows the mean-reverting process.When applied to valuate the MRCR of a coalmine,this model gives higher values than the one-factor model and the NPV.This is because the increase of convenience yield can improve the executive oppor- tunity of MRCR.

The three-factor model of evaluating mining rights of coal resources based on options

Since mining rights of coal resources(for short MRCR) could be regarded as a multi-stage compound real option,the evaluation for MRCR can be better solved using op- tion theory than the NPV.In the former research,we developed a two-factor model of evaluating MRCR when the coal spot price and convenience yield are stochastic based on option theory.On the basis of this two-factor model,we set up a three-factor model of evaluating MRCR when the interest rate followed a stochastic process.Through a real example application,we found the model can get higher values than the two-factor model and the NPV.This is because considering the volatility of interest rate can improve the executive opportunity of MRCR.

Characteristics of Coalbed Methane Resources of China

The paper deals with the coalbed methane gas-bearing characteristics such as the gas content, theoretical gas saturation, gas concentration and abundance, as well as coal reservoir characteristics such as the adsorption, desorption and permeability of China's coal reservoirs. The paper also introduces the resources of coalbed methane with a gas content ≥ 4 m3/t and their distribution in China.

Conjunctive Utilization of Water Resources at the Yulin Coal-Mine Base in China

Shortages in water resources and the fragile ecosystem by coal-mine water affect the Yulin coal-mine base in northwest China, so taking coal-mine water into account is an important issue for the sustainable management of water resources. This paper aims to explore how the Yulin coal-mine base can improve its conjunctive utilization of water resources. Integrated utilization is proposed by establishing a multi-objective, multi-water-source, optimal-allocation model;setting up an integrated information platform;and giving very useful measures and policy suggestions to the local government. Finally, this research can also serve as an example of integrated water utilization for other energy bases.

Coupling Relationship between Integrated Land Consolidation and Farmland Scale Management in Villages over Coal Resources:A Case Study of Zezhou County in Shanxi Province

Through field sampling survey of 18 villages over coal resources in 3 townships and towns in Zezhou County,Jincheng City,Shanxi Province,this paper analyzed the favorable conditions and obstacles for villages over coal resources to carry out farmland scale management.On this basis,combined with the integrated land consolidation measures in villages over coal resources and their effectiveness,and using the principles of system dynamics,it studied the coupling relationship between integrated land consolidation in villages over coal resources and farmland scale management and built a coupling model.It found that the integrated land consolidation system of villages over coal resources has a coupling relationship with the external and internal conditions of the farmland scale management system at the regional and project scales.The two systems interact with and influence each other through the"bridge"of"agricultural modernization condition".The study indicates that at the same time of integrated land consolidation of villages over coal resources caring about the improvement of internal conditions,it is also necessary to improve the external conditions of farmland scale management through regional scale measures such as laws and policies,to support the implementation of land consolidation projects,and realize farmland scale management.

Future of Renewable Resources in an Area Burdened by Brown Coal Mining

This contribution is focused on a possible utilization of renewable energy resources in the Podkrušnohoří?region (Chmomutov, Most, Teplice, ústí nad Labem districts) in the northern part of the Czech Republic after the end of brown coal mining in 2055. Results of the research describe current share of renewable energy resources (solar, wind, water, biogas) in the model area, and a future energy potential in order to ensure sustainable development of an anthropogenically burdened region. Aim of this contribution is to determine, which renewable energy resources would be the most suitable for energy production after the end of brown coal mining. It also describes current and possible use of geothermal power as there are registered heat flow anomalies in the area.

RESEARCH ON THE THEORY AND METHODS OF COMPREHENSIVE EVALUATION OF REGIONAL COAL RESOURCES

consists of forecasting for the total reserves of regional mineral resources and evaluation,compreIn general,based on evaluated objects and factors involved,evaluation of mineral resources hensive evaluation of regional mineral resources, and economic and technical evaluation of deposits. Here a region can be a country, a province, or a mining area, while a deposit is mainly related to a single type of mineral, although it can contain more than one types of minerals. In the past, to assess mineral resources was primarily to evaluate and forecast the total reserves of regional mineral resources. With the advancement of science, technology, and economy, the evaluation of mineral resources has developed from forecasting the reserves of them to comprehensively evaluating them on the basis of numerous factors.

Monte-Carlo Method for Coalbed Methane Resource Assessment in Key Coal Mining Areas of China

Monte-Carlo method is used for estimating coalbed methane （CBM） resources in key coal mining areas of China. Monte-Carlo method is shown to be superior to the traditional volumetric method with constant parameters in the calculation of CBM resources. The focus of the article is to introduce the main algorithm and the realization of functions estimated by Monte-Carlo method, including selection of parameters, determination of distribution function, generation of pseudo-random numbers, and evaluation of the parameters corresponding to pseudo-random numbers. A specified software on the basis of Monte-Carlo method is developed using Visual C＋＋ for the assessment of the CBM resources. A case study shows that calculation results using Monte-Carlo method have smaller error range in comparison with those using volumetric method.

Estimating regional coal resource efficiency in China using three-stage DEA and bootstrap DEA models

Based on three-stage data envelopment analysis(DEA) model estimates of resource utilization efficiency of coal,we selected 29 provinces from China's 2012 input-output data and used the bootstrap DEA model to correct the bias.The results show that the mean overall technical efficiency,pure technical efficiency,and scale efficiency was 0.833,0.998,and 0.711 in 2012,respectively.Moreover,the comprehensive technical efficiency score indicates that the scale is invalid.Area utilization efficiencies for the eastern,central,and western regions were 0.917,0.731,and 0.629,respectively.The results prove that there are significant differences in the distribution of coal resources utilization efficiency across regions.

Economic Transformation Capacities and Developmental Countermeasures of Coal-resource-based Counties of China

In China,the economic systems of many small-scale resource-based regions are confronted with realizing sustainable development through economic transformation. This paper,taking 37 coal-resource-based counties in China as objects,evaluates the economic transformation capacities of the counties by principal component analysis (PCA). Based on the comprehensive principal component values of >1,0–1 and <0,the economic transformation capacities of the counties are classified into strong,common and weak grades. Then,the paper proposes the developmental countermeasures according to different transformation capacities. For the counties with strong transformation capacities,it is crucial to make scientific positioning and rationally exploite resources in view of the developing characteristics and modes of those counties; as for the counties with common transformation capacities,the preparation and perfection of basic transformation conditions are still important aspects; as for the counties with weak transformation capacities,shifting from ″passive transfromation″ to ″active transformation″ in light of resources conditions is necessary.

Resource types, formation, distribution and prospects of coal-measure gas

Coal-measure gas is the natural gas generated by coal, carbonaceous shale, and dark shale in coal-measure strata. It includes resources of continuous-type coalbed methane (CBM), shale gas and tight gas reservoirs, and trap-type coal-bearing gas reservoirs. Huge in resources, it is an important gas source in the natural gas industry. The formation and distribution characteristics of coal-measure gas in San Juan, Surat, West Siberia and Ordos basins are introduced in this paper. By reviewing the progress of exploration and development of coal-measure gas around the world, the coal-measure gas is confirmed as an important strategic option for gas supply. This understanding is mainly manifested in three aspects. First, globally, the Eurasian east-west coal-accumulation belt and North American north-south coal-accumulation belt are two major coal-accumulation areas in the world, and the Late Carboniferous–Permian, Jurassic and end of Late Cretaceous–Neogene are 3 main coal-accumulation periods. Second, continuous-type and trap-type are two main accumulation modes of coal-measure gas;it is proposed that the area with gas generation intensity of greater than 10×10^8 m^3/km^2 is essential for the formation of large coal-measure gas field, and the CBM generated by medium- to high-rank coal is usually enriched in syncline, while CBM generated by low-rank coal is likely to accumulate when the source rock and caprock are in good configuration. Third, it is predicted that coal-measure gas around the world has huge remaining resources, coal-measure gas outside source is concentrated in Central Asia-Russia, the United States, Canada and other countries/regions, while CBM inside source is largely concentrated in 12 countries. The production of coal-measure gas in China is expected to exceed 1000×10^8 m^3 by 2030, including (500–550)×10^8 m^3 conventional coal-measure gas,(400–450)×10^8 m^3 coal-measure tight gas, and (150–200)×10^8 m^3 CBM.

Construction of Green Theoretical Framework of Coal Resource Capitalization

In recent years, the Chinese government has asked enterprises to follow the path of “green development”. This requirement naturally becomes the guiding ideology of coal resource capitalization theory. this paper focuses on the core contents of the green development of coal resource capitalization, and uses the software of ROSTCM6 and UCINET to construct six frameworks of the green theory of coal resource capitalization with the method of “Condensed Subgroup”: the basic theory of capitalization, the conservation theory of capitalization, the environmental protection theory of capitalization, the harmonious coexistence theory of capitalization, the mainline development theory of ecological industry of capitalization Industrial theory, benign cycle sustainable development theory of capitalization, the paper further designs the outline content of the framework.

Paths and strategies of resource-exhausted city transformation: A case study in coal city Pingxiang of Jiangxi Province

Appearance and exhaustion of the resource city is an inevitable objective phenomenon in the process of industrialization. Transformation of the resource city became the focus of attention with highlighting problems and contradictions in the city. The paper places emphasis on path selection and transformation strategies of resource-exhausted city transformation taking the coal city Pingxiang as an example. From the perspective of profi le and effectiveness of transformation in Pingxiang city, the paper analyzes the main problems in the city transformation, points out its main path direction from economic transformation, social transformation and ecological transformation, and fi nally presents transition strategy and policy recommendations to the city.