Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Diamond A precious stone consisting of a clear and colourless crystalline form ...
百度试题 结果1 题目5. Coal consisting (consist) mostly of carbon is the sec-ondary energy in this country. 相关知识点: 试题来源: 解析 答案见上 反馈 收藏
2005). Usually it has been considered that As exists in coal with inorganic affinity because As is concentrated in heavy density fractions enriched in pyrite or clay. But some researchers (Minchev and Eskenazy, 1972; Kryukova et al., 1985; Goodarzi, 1987) proved that As is also present in...
It is mostly applicable to a horizontal fracture when the coal seam does not fracture, but the junction at the roof fractures, depositing sand in a circular or elliptical pattern. This usually happens in a shallow well when the vertical stress, σv, is the lowest stress. Using the Perkins...
is altered to form lignite and coal through metamorphism. The pressure of the accumulated layers of overlying sediments and rock upon the submerged plant matter forced out much of the water and caused some of the volatile substances to escape and the nonvolatile carbon material to form a more ...
"The development of unconventional energy and renewable energy can change not only the coal-dominated energy mix, but also brings about multiple possibilities for coal conversion pathways …" Shift from High-Carbon Development to Efficient Utilization of Coal with Near-Zero Emissions It is necessary ...
A two-dimensional unsteady seepage model for coal using a finite element program is developed, and the temporal variations of key factors such as water pressure and hydraulic gradient are analyzed in this paper. Additionally, the triaxial rock mechanical
Fixed carbon content in Figure 1.19 is calculated on a dry, mineral matter-free basis. Figure 1.19 also shows the comparison between heating value and rank with the heating value calculated on a moist, mineral matter-free basis. Note that the heating value increases with increasing rank but ...
Anthracites include a variety of slow-burning fuels merging into graphite at one end and bituminous coal at the other. They are the hardest coals on the market, consisting almost entirely of fixed carbon, with the little volatile matter present in them chiefly as methane, CH4. Anthracite is ...
is limited. In addition, the roof lithology of coal seam is mostly mudstone, the medium sandstone, fine sandstone and siltstone are distributed in the north and south parts. As shown in Fig.4b–e, the thicknesses of Nos. 61, 63, 71and 8 coal seams are mostly at intervals of < ...