Intelligent and ecological coal mining as well as clean utilization technology in China: Review and prospects

Coal is an essential fossil fuel in China; however, coal mining and its utilization are being under the increasing pressure from ecological and environmental protection. Therefore, the consulting project "Technical Revolution in Ecological and Efficient Coal Mining and Utilization & Intelligence and Diverse Coordination of Coal-based Energy System," initiated by Chinese Academy of Engineering, puts forward three stages(3.0, 4.0 and 5.0) of China's coal industry development strategy. Aimed at "reduced staff,ultra-low ecological damage, and emission level near to natural gas," breakthroughs should be achieved in the following three key technologies during the China Coal Industry 3.0 stage(2016–2025): including intelligent coal mining, ecological mining, ultra-low emission and environmental protection. This paper focuses on the development trends of the China Coal Industry 3.0 and its support for China Coal Industry 4.0 and 5.0 is analyzed and prospected as well, which may offer technical assistance and strategy orientation for realizing the transformation from traditional coal energy to clean energy.

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.

Rare Earth Element Geochemistry of Late Palaeozoic Coals in North China

Abstract: Instrumental Neutron Activation Analysis (INAA) was done to determine the abundances of rare earth elements (REE) of 58 samples of Late Palaeozoic Carboniferous-Permian coals and related rocks in North China. Detailed study of REE geochemistry shows that the ?REE of most coals studied in this paper is in a normal range between 30×10?6 and 80×10?6 with a mean of 56×10?6. The REE in the Taiyuan Formation in the northern part of North China are much richer than those in the southern part. This is due to the shorter distance to the source area in the north. Moreover, the ?REE is in positive correlation to coal ash, especially closely related to the content of clay minerals <2 μm in size. This reveals that most REE were carried by terrigenous clastic materials, especially fine clay minerals. In the coals the light REE (LREE) are much richer than the heavy REE (HREE), and the LREE/HREE ratio in coals generally varies from 2 to 8. The LREE/HREE ratio of high-ash, low-sulphur coals is higher than that of low-ash, high-sulphur coals, and is even higher in the roof and floor rocks, reaching 12 with the highest (up to 21) in pyrite concretions, which shows that the HREE have a stronger affinity to organic matter in a reducing environment influenced by seawater. Furthermore, Eu is generally depleted in coals. The REE chondrite-normalized distribution patterns are very similar in coals of the whole of North China. From the REE geochemical characteristics it can be concluded that during the formation of Late Palaeozoic Carboniferous-Permian coals in North China, the supply of terrigeneous materials remained quite stable. The ?REE in low-ash, high-sulphur coals is relatively low and the REE are mainly carried by fine-grained minerals and organic matter and a certain percentage of REE are adsorbed by organic matter; while the ?REE in high-ash, low-sulphur coals is higher and the REE are mainly present in detritus. The ?REE of magmatism-influenced coals is the highest, which suggests that the introduction of magmatic substances may increase the ?REE, thus causing the REE distribution patterns to show an abnormal feature. Moreover, some harmful elements such as U, W and As usually increase when the coals are influenced by magmatism.

Coal fires in China

Coal fires have a very long history in China; the oldest coal fires have being burning for many million years. Up to now more than 56 coal fires spots were distin-guished. They mainly locate in West-North of China, North of China and East-North of China. About millions of tons of coal have been burned in fires every year. Xinjiang Autonomy is the most serious region in coal fires as it has 38 coal fires spots and about 6.85 million tons of coal was burned every year. Coal fires in China ignited by wildfires, spontaneous combustion and human being during mining activities. These fires have re-leased about 0.9 million tons of gasses (including CO, CO2, SO2, NO2 CH4, CO2, H2S etc.) into the atmosphere every year, most of which are brought to the east by wind and result-ing more heavier air pollution in northern China.

Vulnerability and Sustainable Development Mode of Coal Cities in Northeast China

In this study, by carrying on the spot investigation to the seven coal cities in Northeast China and interview-ing with the local authority and the residents, the authors definite the vulnerability that is closed to exposure, sensitiv-ity and resilience, and set up vulnerability model of coal cities in Northeast China. At the same time, the authors broadly illustrate how the components of natural-social-economic system act in the coal area, so as to probe the ways to reduce vulnerability more effectively, such as preferential national policy and so on. Furthermore, the article studies the relationship between vulnerability and sustainable development. Vulnerability is a spatio-temporal function of sus-tainable development. The regional sustainable development refrains the spiral ascending of vulnerability. And the re-gional vulnerability and sustainable development appear in turn. Then the article analyzes the natural vulnerability, so-cial vulnerability and economic vulnerability of coal cities in Northeast China. At last, combing vulnerability model and situation of coal cities in Northeast China, the authors put forward regional technology innovation mode, multi-dimension structure transformation mode, attracting investment mode and recycling economy mode to reduce vulnerability.

Significant Mercury Isotope Anomalies in Hydrothermal Altered Coals from the Huaibei Coalfield,China

Igneous intrusion into coal-bearing strata can cause an abrupt increase of temperature-pressure and trigger hydrothermal circulation at the igneous rock-coal contact zone. The conductive heat of intruded lnagma and convective migration of secondary hydrothermal fluids have been observed to significantly alter the concentrations and modes of occurrence of mercury （Hg） in thermally-intruded coals.

Hydrocarbon-Generating Characteristics of Barkinite-Rich Coals from Late Permian Longtan Formation, South China

Leping coal (including barkinite\|rich coal) is a unique kind of coal, which is widely distributed in the Late Permian Longtan Formation, South China. In this paper, Rock\|Eval, Py\|GC and simulation experiment via an open\|system were used to study the hydrocarbon\|generating potential, hydrocarbon composition, and hydrocarbon\|generating model of barkinite\|rich coals from the Shuicheng coal field of Guizhou Province, Southwest China. The results show that barkinite\|rich coals have high hydrocarbon\|generating potential, with S\-1+S\-2 being 211-311mg/g, and can produce large amounts of hydrocarbon at the high\|maturity stage, mostly within the temperature range of 420-450℃ (corresponding to VR\-0 1.1-1.5%); barkinite\|rich coal is one of the better oil sources and light hydrocarbon and wet gas are the major hydrocarbon components, which account for 45% and 33% of the total hydrocarbons, respectively. These characteristics are of importance for exploring oil and gas resources in the Late Permian Longtan Formation coals, Southwest China.\;

Sequence Stratigraphy of the Jurassic Coal Measures in Northwestern China

The sequence stratigraphy of the Jurassic coal measures of northwestern China has been studied based on data from outcrop and borehole sections. Because of the geological background and the diversity of basin types, such as isochronisms of coal seams and recognition of key sequence boundaries, it is rare to summarize and correlate sequence structure and framework. The types and recognition characteristics of the sequence boundaries of the Jurassic coal measures are revealed by comparing climatic characteristics, structural styles and the base level cycle. A total of five third-order sequences and 15 systems tracts have been subdivided and the sequence stratigraphic framework has been reconstructed confirming that the thick coals accumulated in the late stage of transgression system tracts of sequence I （SQ I） and sequence III （SQ III）. This idea is of important academic significance for instructing coal resources exploration, and enhancing geological effects of prospecting engineering. It is also of practical significance for guaranteeing construction of the large-scale coal production base in northwestern China, accelerating the westward development of the coal industry stratagem.

Mercury in coal and its emission by coal combustion in the Northeast China

This paper reports on the mercury content distribution in coals produced in the Northeast of China, and the east of Inner Mongolia, and transmission of mercury from coals into the burned products. The arithmetic average value of mercury content in coals is 0.158 mg/kg, and the mercury content shows considerable positive correlation with ashes in coals. The mercury content in fly ash is increased as the particle diameter of fly ash decrease. After combustion, 23.1—26.9 percent of mercury in coals enters fly ash,and 56.3—69.7 percent of mercury escapes into atmosphere. We estimated that the amount of mercury in raw coals produced in the Northeast of China and the east Inner Mongolia was 30.9 tons in the whole year and the amount emitted into atmosphere was 20 30 tons in 1990.

New Breakthroughs in China's Coal Gasification Technology

It is learned from the 2013 Summit Forum on Strategic Development of Coal-to-Natural Gas in China that the China Sedin Engineering Company,Ltd.has developed with independent intellectual property rights two experimental furnaces for pressurized gasification of crushed coal,5 m

Distribution and genesis of mercury in natural gas of large coal derived gas fields in China

The mercury content in natural gas samples from more than 500 gas wells in eight large gas bearing basins of China was tested, mercury release experiments on two coal samples from different areas were conducted, and the mercury content of 11 coal samples from different gas wells of Ordos Basin was tested. The mercury distribution of the coal derived gas has three features: The first is that mercury content of coal derived gas is generally much higher than that of oil derived gas, the second is that the coal derived gases from different fields vary widely in mercury content, the third is that the mercury content in coal derived gas increases with the increase of production layer depth. Mercury in coal derived natural gas mainly originates from the source rock. Besides three evidences, namely, coal derived gas mercury content is much higher than that of oil derived gas, mercury content of gas with high carbon dioxide content decreases with the increase of carbon dioxide content, and the coal bearing strata have the material base to generate natural gas with high mercury content, the pyrolysis experiment of two coal samples show that coal can produce natural gas with high mercury content during the process of thermal evolution. The mercury content of coal derived natural gas is controlled mainly by the temperature of source rock and the sulfur environment of reservoir. According to lithospheric material cycling process and oil-gas formation process, the formation of mercury in coal derived gas can be divided into four stages, transportation and deposition, shallow burial, deep burial, and preservation and destruction.

A Carbon Isotopic Stratigraphic Pattern of the Late Palaeozoic Coals in the North China Platform and Its Palaeoclimatic Implications

This paper gives the stable carbon isotopic data in coals from the Late Namurian to Kazanian stages in the Serteng Mt., Xishan and Huainan coalfields of the North China Platform. Its stratigraphic pattern shows that several isotopic shifts are apparent, and the large δ13C negative shifts (approximately 2.5 to 3.0 %%) occurred during the Stephanian, Artinskian and Kazanian are observed in three Permo-Carboniferous coalfields. Those negative shifts are neither related to the coal rank and coal macerals, nor caused by the variety of peat-forming plants. The general decrease in the δ13C values of the Stephanian, Artinskian and Kazanian coals is consistent with an overall decrease in the δ13C values of ambient atmospheric CO2 and/or a relative increase in atmospheric Pco2 during the coal-forming periods. Therefore the authors postulate that the oxidation of peat, and the δ13C-depleted CO2 flux into the atmosphere during the above stages may have contributed to coeval palaeoclimatic warming by way of the greenhouse effect.

The Goal Set For China's Coal Industry During the Ninth Five-Year Plan Period

Coal is China’s principal source of energy,accounting for about 75percent of primary energy.This pattern will remain unchanged fora long period of time from now on.Thanks to the efforts made duringthe Eighth Five-Year Plan period,the general situation for the coalindustry is now good.

Present Status of China's Coal Industry

Coal is China’s principal source ofenergy, accounting for about 75percent of primary energy. This patternwill remain unchanged for a long period oftime from now on. Thanks to the effortsmade during the Eighth Five-Year Plan period,the general situation for the coal industry isnow good.

DATONG MINING BUREAU——THE LARGEST COAL ENTERPRISE IN CHINA

The Datong Mining Bureau, locatedin the southwest of Datong, famousfor its history and culture, is thelargest coal enterprise in China. It has 200,000staff and workers and fixed assets of RMB9.81 billion. Its annual output of raw coal is37 million tons, and its sales income totalsRMB 4.62 billion, of which RMB 1.18 billioniS tax and profits.

Valency Study of Vanadium in Stone Coal of Southern China

Vanadium - bearing stone coal is a new resource of vanadium. V in stone coal mainly exists in three oxidation states: 7.84% V(III), 72.08% V(IV) and 20.08% V(V). The change and distribution of valency during oxidizing roasting shows that organic matter in the coal determines the valency at low temperatures. At about 450°C, V(III) is completely oxidized to V(IV); above 500°C, temperature is the most important factor for the oxidation of V. At 700-1000°C, 92% of V in the coal has been oxidized to V(V). At higher temperature, no more oxidation of V takes place, equilibrium being established. The role of NaCl in the recovery of V2O5 from the coal is discussed. The best conditions for roasting are an oxidation-chlorination atmosphere, temperature 800°C for 30 minutes, ore:NaCl = 100:10, ηroast reaching 90%.

Geochemistry of Permian Coal and Its Combustion Residues in Huainan Coalfield, China

INAA (instrumental neutron activation analysis) was used to determine the contents of trace elements in coal samples from 11 workable Permian coal seams in Huainan coalfield. With XRFS (X-ray fluorescence spectrometry), the geochemical composition of its combustion residues from Tianjiaan Power Plant and Luohe Power Plant was analyzed. In addition, the electron microprobe was employed to study the chemical composition of some fly ashes and bottom ashes. Compared with those of the coals around the world, most trace elements of the Huainan coal are characterized by a normal abundance. Like most coals worldwide, the elements Se, S, As, Sb, Br, U and Cl are enriched in Huainan coal according to dark's value, while the other elements tend to be diluted. The large fluctuation in the contents of trace elements in this kind of coal demonstrates great differences in coal seams. On the other hand, the contents of these elements are very similar in different bottom and fly ash samples. The elements with low organic affinity tend to concentrate in fly and bottom ash than in coal, especially those elements associated with Fe. However, the elements with strong organic affinity tend to be volatile during the combustion. Moreover, the abundance of the elements in fly ash and bottom ash changes with different densities and with different particle sizes. The bottom and fly ashes consist of glass, lime, mullite, coal residues and ferrite minerals. Some residual chars contain higher contents of volatile elements, such as S, P, Cl and As, indicating that the ash containing more residual chars has a strong adsorption of some hazardous elements, suggesting a possible utilization of power plant ash in the field of water cleaning.