Coalification has been a major focus for coal geology and organic geochemistry research. In recent years, with the development of coalgenerated hydrocarbons and ... Detailed descriptions of the coalification process and parameters used for determining degree of coalification have been described by Stach (1975) and Teichmüller et al. (1979).
Coal forms when swamp plants are buried, compacted and heated to become sedimentary rock in a process called coalification. "Very basically, coal is fossilized plants," James Hower, a petrologist ...
Coal is defined as having more than 50 percent by weight (or 70 percent by volume) carbonaceous matter produced by the compaction and hardening of altered plant remains—namely, peat deposits. Different varieties of coal arise because of differences in the kinds of plant material (coal type), degree of coalification (coal rank), and range of impurities (coal grade).
Coal Geology. Coal is a combustible sedimentary rock formed from ancient vegetation which has been consolidated between other rock strata and transformed by the combined effects of microbial action, pressure and heat over a considerable time period. This process is commonly called 'coalification'. Coal occurs as layers or seams, ranging in ...
During the coalification process, the proportion of porosity contributed by ultramicropores to the total porosity gradually increases, with the contribution rising by %. ... is reconstructed by synchrotron radiation NanoCT experimental to clarify the evolution in the number of pore sizes in coal during coalification; (2) determine the ...
The mechanism of wood coalification initiates with a biochemical process where wood is transformed into peat (peatification) and then trough aerobic and anaerobic reactions (humification and gelification) into soft brown coal (lignite) [3537].Subsequently, via a geochemical process through elevated temperature and pressure, soft brown coal is converted into hard brown coal (anthracite) [2 ...
Coalification is a chemical process in which hydrogen and oxygen are lost from the original peat fool, increasing the ratio of carbon to other elements. This involves alteration to the remaining molecules of the material, in particular the conversion of lignin to vitrinite. Coalification is not an allornothing process: rather it produces coal ...
misc{etde_431984, title = {FTIR study of the evolution of coal structure during the coalification process} author = {Ibarra, J V, Munoz, E, and Moliner, R} abstractNote = {This paper reports on a study of a series of coals varying in rank from peat to semianthracite using Fourier Transform infrared spectroscopy (FTIR) and curvefitting analysis in order to gain additional information on coal ...
A clear relationship between this naturalcoalificationlike alteration of coal quality and the quantity of removed water was determined. The pilot plant consisted of four autoclaves. It led to the development of the DKprocess using saturated steam, and later, a new DKprocess using saturated and superheated steam.
Curvefitting analysis was employed to characterize coal structural evolution during the coalification process. The study was carried out on samples of a natural evolutionary series as well as ...
The coalification process produces water and carbon dioxide during lignite and lowrank coal formation, while in lowrank bituminous coals with more than 29 % volatile matter, mainly carbon dioxide is evolved followed by methane with small amount of heavier hydrocarbons, carbon monoxide, and nitrogen. As the lowrank coal is subjected to ...
With the progress of science and technology, the view that coal is transformed from higher plants has been accepted as time goes. However, limited by characterization methods and conditions of laboratory simulation of the coalification process, the chemical changes in higher plants during coalification are unclear.
CBM consists of methane adsorbed into the coal matrix during coalification when plant material turns to coal. This process takes place underground in coal mines, presenting safety risks. Increasing domestic gas output can benefit from CBM extraction. It is often referred to as "sweet gas" due to the absence of hydrogen sulfide.
In the process of coal mining, prevention and control of water hazard is essential. It is the precondition for water hazard control to detect and determine the distribution of underground waterconducting channels. In urban environments, traditional methods such as active source seismic exploration and transient electromagnetic exploration commonly used in the field are difficult to carry out ...
The breakdown mechanisms of coal structures are important for coalification process, mining security, climate change, and comprehensive utilization of coal [2]. Temperature is a major influence factor in coalification, where aliphatic structures (or functional groups) are removed and the aromatic materials condense into larger cluster [3], [4].
There are four major types (or "ranks") of coal. Rank refers to steps in a slow, natural process called "coalification," during which buried plant matter changes into an ever denser, drier, more carbonrich, and harder material. The four ranks are: Anthracite: The highest rank of coal. It is a hard, brittle, and black lustrous coal, often referred to as hard coal, containing a high ...
There is a wellknown coalification jump (occurs in the subbituminous A coal stage, R o, max = %) during the early coalification process (Li et al., 2017a; O'Keefe et al., 2013), where the ...
This study investigated the exothermic characteristics of coal during its lowtemperature oxidation and determined the main factors affecting the exothermic intensity of the oxidation process. Four coal samples with different degrees of coalification were prepared to study the variation in the exothermic heat of oxidation at temperatures ...
The main factors that influence the coalification process are temperatures, pressures and time of duration. The coalification can be further divided into the diagenesis and metamorphism of coal. The process that makes peat or sapropelite turned into lignite or saprodite is called the diagenesis of coal.
The metamorphic process of coal is often affected by magma intrusion and stratigraphic tectonic movement. It is of great significance to analyze the evolution characteristics of coal structure under different metamorphisms in the study of coalification. Nineteen coal samples collected from Huainan coalfield (Zhangji coal mine, Panji4 coal mine, and Xinji2 coal mine) were tested by electron ...
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