Chinese coal industry and coal mining engineering education

While the U.S. coal industry has been steadily declining in recent years, it is interesting to note that China’s large coal industry has continued to grow. In fact, it is larger than the rest of the world combined in all categories, including number of people employed, raw coal annual production and imports, coal consumption and college mining engineer training. College education of coal mining engineers China has 10 major universities specializing in coal mining engineering. These programs offer B.S., M.S. and Ph.D. curricula (Fig.1). In addition, there are more than 10 universities that also have a minor in coal mining engineering. For those 10 universities shown in Fig. 1, the 2023 enrollment and graduates of each university are shown in Table 1. The numbers there do not include those who majored in safety, which includes the mine-ventilation and accident-management aspects of mining curriculum, because it is administered under “safety college,” independent of “mining or energy college,” where mining engineering programs normally reside. In addition, several universities other than those listed in Table 1 and Fig. 1 emphasize hard-rock curricula and coal mining as a minor. In China, B.S., M.S. and Ph.D. are four-, three- and four-year programs, respectively. Enrollment at the M.S. and Ph.D. degree level is assigned by the Education Department of the central government. Undergraduate freshmen must pass a unified entrance examination and are selected by an individual university, while first-year M.S. and Ph.D. students must pass an entrance examination held by each individual university. Each degree level has a minimum hour of course work to complete and requires successful completion of a graduation project or study report, thesis and dissertation for the B.S., M.S. and Ph.D. levels, respectively. Research funding for M.S. and Ph.D. candidates is abundant and generally comes from two sources: (1) From the Chinese National Science Foundation, which solicits proposals annually and whose project award is highly competitive. The proposals can be either theoretical or applied in nature. In addition, there are some provincial scientific and research projects, all from the government. (2) From the 4,407 individual coal mines, most of which have an annual budget, at least 3 percent of their capital equipment expense, for the problem-solving of technical issues encountered in their operations. These type of projects are applied in nature and are directly negotiated between mine management and university professors. Sources of energy and coal production, consumption and imports Sources of energy in China are derived primarily from three types: (1) coal (56.2 percent), (2) petroleum (17.9 percent) and (3) natural gas (8.4 percent). The share of primary electricity and other energy sources in total energy was 17.5 percent in 2022 (Fig. 2). The Chinese coal industry employs a total of 2.85 million people with approximately 1 million miners. The remainder are management and supporting services personnel.Proven coal reserves are about 207.89 Gt (229.15 billion st) and increasing as exploration continues to find new reserves in the northern and western regions. Figure 3 shows the annual raw coal production and imports from 2010 to 2022. Production ranged from 3.43 Gt to 4.56 Gt (3.78 billion and 5.02 billion st) and has been increasing in recent years. In the same period, annual imports ranged from 183 Mt to 327 Mt (202 million and 360 million st) and has been decreasing in recent years. Coal is produced from 4,407 mines with a majority of them being underground mines (76.8 percent), and the remainder surface mines (23.2 percent). Figure 4 shows the area distribution of coal production with north and northwest regions such as Shaanxi, Xinjiang and inner Mongolia accounting for the great majority, away from the populated eastern region. All coal mines are owned by central, provincial or local governments. Private mines exist, but they are all small ones, producing less than 200 kt/a and 300 kt/a (220,000 stpy and 330,000 stpy). These private mines need to receive safety management from the government and state-owned coal mine companies. Coal use in China is mainly for electric power (55 percent) (Fig. 5), followed in sequential order by coke making (18 percent) for the steel industry, building materials (11.7 percent), chemicals (12.92 percent) and others. Coal mining in thick and ultra-thick coal seams Coal reserves in China are complicated geologically and vary from region to region. Thick seams refer to those equal to or larger than 3.5 m (11.5 ft) in thickness,while those more than 7 m (23 ft ) thick are ultra-thick seams. Thick and ultra-thick seams are mostly located in Shanxi Province, Inner Mongolia and Xinjiang. The mining method employed is mainly longwall mining of various degrees of mechanization. Room-and-pillar mining was introduced from the United States in the early 1980s and its practice is currently much reduced, mainly to extract remnant pillars that were left behind for the protection of surface structures.Modern, fully mechanized longwall mining technology was introduced by U.K. and German equipment manufacturers in early 2000 for medium and thick seams in China’s western region. The equipment was developed in conjunction with, and originally for, the U.S. coal industry in the 1980s to early 1990s. Consequently, for top-performance mines, longwall equipment and panel layouts are similar to those of U.S. coal mining. Two methods have been used to extract the thick coal seams in China: (1) “one-slice, whole-seam mining,” in which the equipment is capable of cutting out the whole seam in one trip and (2) “top coal caving,” in which the coal is undercut by a set of equipment similar to the one-slice whole-seam method, leaving the remainder of the top coal to cave naturally (Fig. 6). One-slice, whole-seam longwall mining. China began to develop its set of longwall equipment for 3.5 to 4.5 m (11.5 to 14.8 ft)-thick coal seams in the mid-1980s (Wang et al., 2023). In 2004, a full set of longwall equipment was developed and began production for 5.5 m (18 ft)-thick seams. During 2008 to 2011, equipment for 6 m (19.7 ft)-thick seams was successfully applied, and in 2009-2013, a set of equipment for mining height of 7 m (23 ft) went into production in Inner Mongolia, leading to the formation of coal mines with 30 to 40 Mt/a (33 million to 44 million stpy) raw coal (Peng et al., 2013). A few innovations for the shields of ultra-large mining height include the large-diameter, double-telescope hydraulic cylinder, special high-strength steel and welding technique and structural stability. The governing concept of Chinese coal mining is to recover 100 percent of the coal seam being mined. Therefore, as thicker coal seams are found in the Inner Mongolia coal fields, the need to develop equipment of larger mining height is required. Consequently, equipment for mining heights of 8.2 m (26.9 ft), 8.4 m (27.6 ft) and finally 10 m (32.8 ft) were developed sequentially. During 2014 to 2016, a set of longwall equipment for 8 m (26.2 ft) mining height was developed and went into production in 2016, followed by the 8.8 m (28.9 ft) mining height in 2018. Finally, equipment for 10 m (32.8 ft) mining height was developed and went into production in 2020. For the 10 m (32.8 ft) mining height, the whole set of face equipment (Fig. 7) is rated at 22,000 kW (30,360 hp) and weighs 20 kt (22,000 st). The shearer’s total power is rated at 3,350 kW (4,623 hp), drum diameter is 4.8 m (15.7 ft), cutting web is 865 mm (34 in.), and it weighs 262 t (288 st); shields are two-leg, 2.4 m (8 ft) wide, load density is 283 psi (1.95 MPa) with a 630 mm-diameter cylinder, and it weighs 127 t (140 st), with setting load of 2,237 t (22,368 kN) and yield load of 2,900 t (29,000 kN); AFC 94.5 × 63 × 21.3 in. (2,400 × 1,600 × 540 mm). Longwall top coal caving mining (LTCC). Top coal caving mining was introduced from Europe in 1984. The major difference between equipment used for LTCC and for one-slice, whole-seam mining is that the shield for LTCC has two chain conveyors: one in front, just like for the one-slice, whole-seam mining, and the other in the rear under an extended rear canopy (Fig. 8). Consequently, the coal transportation at the headend required two sets of transfer frames (Fig. 9). The latest model for LTCC in a 12 m (39.4 ft) coal seam is to use the set of equipment designed for 7 m (23 ft) mining height with shield rated at 2,100 t (21,000 kN) (Wang et al., 2023). n Acknowledgment This research is partially supported by the Graduate Education Reform Project of Henan Province (2023SJGLX033Y). References S.S. Peng, H.M Li, Y. Zhou and J.Y. Cheng. Ultra-Thick Seam Longwall Mining in China. Coal Age, October 2013, 38-43. S.S. Peng. Longwall Mining, 3rd edition, CRC Press, Taylor and Francis Group, 2020, 546 pp.G. Wang, Y. Pang, Y, Xu, L. Meng, and H. Han. Development of Intelligent Green and Efficient Mining Technology and Equipment for Thick Coal Seam. Journal of Mining & Safety Engineering, 40(5), September, 2023, 882-893 (in Chinese). J.C. Wang and Y. Li, Development of Coal Industry and Mining Engineering Education. 34 presentation PPTs, China University of Mining and Technology Beijing, December 2020 (in Chinese).

Chinese coal industry and coal mining engineering education

Authored by: Syd S. Peng, Wenbing Guo and Yang Li

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