Anthracite Production Research Articles

Monitoring and Analysis of Land Subsidence in Jiaozuo City (China) Based on SBAS-InSAR Technology

Jiaozuo, located in the northwest of Henan Province, is one of the six major anthracite production bases in China. It is susceptible to land subsidence due to over a hundred years of mining history, continuous urbanization, frequent human activities, etc., which poses a great threat to urban infrastructure construction and people’s production and lives. However, traditional leveling techniques are not sufficient for monitoring large areas of land subsidence due to the time-consuming, labor-intensive, and expensive nature of the process. Furthermore, the results of conventional methods may not be timely, rendering them ineffective for monitoring purposes. With the continuous advancement of urbanization, land subsidence caused by groundwater extraction, ground load, and other factors in daily life poses a great threat to urban infrastructure construction and people’s production and lives. In order to monitor the land subsidence in the area of Jiaozuo city, this article uses the Sentienl-1A satellite data covering the city from March 2017 to March 2021 to obtain the accumulated land subsidence and the average land subsidence rate based on the Small Baselines Subset InSAR (SBAS-InSAR) technology. The results indicate that the surface of Jiaozuo area is generally stable, and there has been no large-scale settlement. The settlement rate is roughly between −1 mm/a and 2.2 mm/a, and the areas with obvious land subsidence are mainly located in the southeast and east of Jiaozuo city center. After field investigation, it was found that the land subsidence is mainly caused by two reasons: groundwater excessive mining and excessive surface load. In the northeast of Jiaozuo city, there is a certain uplift area. After on-site investigation, it was found that the area is connected to a tailings pond of an aluminum mine, constantly accumulating abandoned rock masses and sediment, causing an annual uplift rate of +6~+ 24 mm/a. The large-scale extraction of groundwater from farmland in the urban–rural integration area for irrigation of wheat has led to the settlement of buildings in the area with a rate of −11–−74 mm/a.

Structural and evolutionary characteristics of pores-microfractures and their influence on coalbed methane exploitation in high-rank brittle tectonically deformed coals of the Yangquan mining area, northeastern Qinshui basin, China

The Yangquan mining area is an important anthracite production base in China, but various types of tectonically deformed coals (TDCs) are well developed in its mines and gas outburst accidents take place frequently. By using methods such as optical microscope observation, mercury intrusion porosimetry (MIP) and low pressure nitrogen/carbon dioxide gas adsorption (LP-N2/CO2GA), we tested the structural and evolutionary characteristics of pores-microfractures and their influence on coalbed methane exploitation in high-rank (Ro,max = 2.00–2.72%) primary structure coals and brittle TDCs (i.e., cataclastic-, mortor-, and granulitic coals) from the Yangquan mining area. The results show that the tectonic deformation can change the pore-microfracture structure of coals and, thus, their reservoir physical properties. In general, with the enhancement of tectonic deformation, the density of microfractures in coal, which become more and more mussy, gradually increases, the total pore volume (TPV) of coal (pores with a diameter of 5.37–27000 nm) and the pore volume of each pore size range increase, with the greatest increase occurring in pores of 100–1000 nm, and the connectivity between pores is gradually reduced as well. From primary structure coals to granulitic coals, the TPV by the Barret-Joyner-Halenda (BJH) model increases with a greater increase in mesopores, and the specific surface area (SSA) by the Brunauer-Emmett-Teller (BET) model shows a trend of “increase-decrease-increase”, while the average pore diameter changes follow the pattern of “decrease-increase-decrease” in 0.7–206 nm. However, tectonic deformation has little effect on micropores with a diameter of less than 1 nm in brittle TDCs. The difference in pore-microfracture structures of different brittle TDCs indicates that the cataclastic coals distribution area is favorable for coalbed methane (CBM) exploitation, while the granulitic coals distribution area is a gas outburst-prone area.

Experimental Investigation for Pore Structure and CH4 Release Characteristics of Coal during Pulverization Process

Qinshui coalfield is the largest coalbed methane and anthracite production base in China. In the process of mine gas prevention and control, there was a larger amount of gas that can be extracted, but even with this, the residual gas pressure is not up to standard. In this paper, in order to analyze its specific reasons, a series of experiments were carried out to investigate the pore structure, particle size distribution, and CH4 release characteristics of anthracite during the pulverization process. Results show that, compared with bituminous coal, anthracite can continuously release a certain concentration of CH4 during the pulverization process. The SEM test exhibits that anthracite possesses more secondary pores while bituminous shows more mineral pores. With the increase of total pulverizing time, the coal particle size is gradually decreased. Furthermore, compared with the pre-pulverized samples, the porosity, pore volume, and surface area of post-pulverized samples are increased, indicating that the closed pores are destroyed to be open pores during the pulverization process. In addition, by combining the gas release concentration and pore volume evolution, it can be inferred that the anthracite may contain more solid solution gas due to the fact that there is a certain amount of gas that can be released when the pore volume tends to be smooth. The research results can provide the theoretical basis for gas extraction in the anthracite mine.

Comprehensive Technical Support for High-Quality Anthracite Production: A Case Study in the Xinqiao Coal Mine, Yongxia Mining Area, China

The effective production of high-quality anthracite has attracted increasing global attention. Based on the coal occurrence in Yongxia Mining Area and mining conditions of a coalface in Xinqiao Coal Mine, we proposed a systematic study on the technical support for the production of high-quality anthracite. Six key steps were explored, including coal falling at the coalface, transport, underground bunker storage, main shaft hoisting, coal preparation on the ground, and railway wagon loading. The study resulted in optimized running parameters for the shearers, and the rotating patterns of the shearer drums was altered (one-way cutting was employed). Mining height and roof supporting intensity were reduced. Besides, loose presplitting millisecond blasting and mechanized mining were applied to upgrade the coal quantity and the lump coal production rate. Additionally, the coalface end transloading, coalface crush, transport systems, underground storage, and main shaft skip unloading processes were improved, and fragmentation-prevention techniques were used in the washing and railway wagon loading processes. As a result, the lump coal production rate was maintained at a high level and fragmentation was significantly reduced. Because of using the parameters and techniques determined in this research, high-quality coal production and increased profits were achieved. The research results could provide theoretical guidance and methodology for other anthracite production bases.

Preheater for Anthracite Carbonization in Rotary Furnaces

Coke production is carried out by coal carbonization. The most frequently used coal is anthracite, which features a very low content of volatile substances that not exceed 7%. Current anthracite production is carried out in rotary furnaces, consists of processes as follows: drying, heating, pyrolysis and calcination. Coke cooling is performed in cooling device located at the end of the furnace. To enhance the performance and reduce the specific heat consumption, use of the preheating device for rotary charge was proposed. The charge granulometry allows using the preheating device based on thin layer principle. Proposed solution was verified by simulations.

Potential for Coal-to-Liquids Conversion in the U.S.-Resource Base

By applying the multi-Hubbert curve analysis to coal production in the United States, we demonstrate that anthracite production can be modeled with a single Hubbert curve that extends to the practical end of commercial production of this highest-rank coal. The production of bituminous coal from existing mines is about 80% complete and can be carried out at the current rate for the next 20 years. The production of subbituminous coal from existing mines can be carried out at the current rate for 40–45 years. Significant new investment to extend the existing mines and build new ones would have to commence in 2009 to sustain the current rate of coal production, 1 billion tons per year, in 2029. In view of the existing data, we conclude that there is no spare coal production capacity of the size required for massive coal conversion to liquid transportation fuels. Our analysis is independent of other factors that will prevent large-scale coal liquefaction projects: the inefficiency of the process and either emissions of greenhouse gases or energy cost of sequestration.

Integrated environmental assessment and pollution prevention in Vietnam: the case of anthracite production

Using the concept of life cycle analysis, the whole life cycle of anthracite production in Vietnam was assessed and the environmental “hot-spots” were identified. These include (i) dust pollution at coal transfer points or piles in storage; (ii) noise pollution resulting from the usage of heavy equipment, and (iii) high volume of acid and turbid mine water discharged into the environment. Pollution prevention and treatment options were identified and discussed in this study which consists of wet treatment of dust, planning, collection and treatment of mine water, planting of trees for dust and noise reduction as well as minimization of erosion. Some recommendations are made for pollution abatement from coal production and improvement of anthracite production in the region.

Pennsylvania Anthracite Mining Industry: A Past--and a Future?: ABSTRACT

The anthracite region in north-central Pennsylvania was one of the earliest areas of coal mining in the United States. Anthracite was used by blacksmiths in Wilkes-Barre as early as 1769, and by 1808, coal was in demand for home heating and industrial markets. Anthracite production reached a peak of 99.6 million short tons in 1917, but has declined to only 4 million short tons in 1983. Reasons for the decline, during a time when energy demand has generally been increasing, include availability of cheaper fuels, unreliability of anthracite supply, labor-intensive mining, difficulty in mechanization of mines because of geologic conditions, depletion of the more accessible coal beds, and cost of correcting environmental problems. Many energy analysts believe that the Pennsylvania anthracite industry is facing extinction. The remaining reserves are, however, extensive; a 1984 study funded by the U.S. Bureau of Mines estimated 19 billion tons of anthracite resources, including a reserve base of approximately 7 billion tons. The cost of anthracite leaving the preparation plant is at least 50% higher than that of bituminous coal mined in the East. However, the anthracite region is closer to major eastern markets, so transportation costs are less for anthracite. Because anthracite has a low sulfur value, the costly scrubber equipment required at power plants using higher sulfur bituminous coal usually is not necessary for anthracite-fired plants. Most mining research has been directed toward the bituminous coal ind stry in the past; similar research is needed in the anthracite industry to develop mechanized, high-productivity mining methods and to improve economic competitiveness. End_of_Article - Last_Page 1436------------