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Underground soft rock mining
Published in A.J.S. (Sam) Spearing, Liqiang Ma, Cong-An Ma, Mine Design, Planning and Sustainable Exploitation in the Digital Age, 2023
A.J.S. (Sam) Spearing, Liqiang Ma, Cong-An Ma
This is the lowest rank of coal and with the lowest energy content. Lignite coal deposits tend to be relatively young coal deposits that have not been subjected to extreme heat or pressure. Lignite is a weak and crumbly rock with a relatively high moisture content as shown on Figure 2.5. It typically has a carbon content of 60–70% based on a dry ash free analysis. Lignite is mainly burned at power plants to generate electricity.
Review of the American mining industry
Published in Tad S. Golosinski, Mining in the New Millennium Challenges and Opportunities, 2020
Gulf Coast lignite is mined using a wide variety of surface mining methods, most of these being either truck-and-shovel mining or dragline mining. Apart from periodic operation related to land reclamation in Illinois, the Gulf Coast is the only region in the US where bucketwheels are used in coalmines. Altogether four bucketwheels installed in three mines help pre-strip overburden for subsequent dragline mining. All BWEs are small by European standards and the mining conditions do not seem to favor wider application of this mining technology.
Physicochemical Properties of Coal
Published in Vivek Ranade, Sanjay Mahajani, Ganesh Samdani, Computational Modeling of Underground Coal Gasification, 2019
Vivek Ranade, Sanjay Mahajani, Ganesh Samdani
Peat is the precursor of coal and is used as industrial fuel in some countries. Its other applications include its use as a highly efficient absorbent for oil spills. Lignite is the lowest rank brown coal that is used as an industrial fuel. Sub-bituminous coal is ranked between lignite and bituminous coal, and its properties also range between those two. It is mainly used as a fuel for power stations. Bituminous coal is typically dark brown or black in color and is mainly used in heat and power applications in manufacturing industries and power plants. Coke is also produced from bituminous coal. Anthracite, the highest rank coal, is harder and glossy black and is primarily used for residential or commercial heating. Graphite is difficult to ignite and is therefore used primarily in pencils and for lubrication.
Experimental study on ash deposition characteristics of dryer exhaust along horizontal tube bundles using digital imaging techniques
Published in Drying Technology, 2022
Jinshi Wang, Yanjun Guo, Yiwen Liu, Yuanzhi Qin, Ming Liu, Junjie Yan
Although renewable energy power has rapidly developed in recent decades in China, thermal power generation still supplies approximately 70% of electricity and plays a significant role in the electric power industry. With its abundant reserves and low price, lignite is considered one of the main fuels for the future electricity generation in China.[1] However, lignite has a comparatively high moisture content and a low calorific value, which result in its low boiler efficiency in a direct lignite-fired power generation system. Lignite-drying technology is a clean and effective way of lignite utilization. A lignite-fired power generation system with predrying can remarkably improve the power generation efficiency.[2–4] The lignite-drying process produces dryer exhaust, which contains a large amount of water vapor. Existing studies confirm that the recovery of latent and sensible heat from the dryer exhaust would improve the energy utilization efficiency.[5–8] The waste heat recovery process in a surface-type heat exchanger is essentially the heat transfer process between the dryer exhaust and thermal transfer medium, usually cooling water.[9] Thus, the heat transfer characteristic is the key issue to design and operate the heat exchanger.
Bacteria solubilization of shenmu lignite: influence of surfactants and characterization of the biosolubilization products
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Hongli Kang, Xiangrong Liu, Yaowen Zhang, Shunsheng Zhao, Zaiwen Yang, Zhipeng Du, Anning Zhou
Among fossil fuel reserves, coal plays an important role in the energy supply of the world. But not all coal reserves are suitable for energy production, compared to high-rank coal, lignite is a kind of low-rank coal with high moisture content, high ash content, low calorific value, high oxygen, sulfur, and nitrogen content. The proven recoverable reserve of Chinese lignite is 130 billion tons, accounting for one-third of all coal reserves. To date, lignite is mainly used to produce electricity and heat through traditional physical and chemical processing methods. Nevertheless, these processes not only need high temperature and pressure but also produce air pollutants such as nitrogen, sulfur and carbon dioxides (Aytar et al. 2013; He et al. 2012; Rahman, Pudasainee, and Gupta 2017). It is therefore necessary to develop efficient technologies to utilize lignite environmentally and economically.
Lignite biosolubilization and bioconversion by Bacillus sp.: the collation of analytical data
Published in Biofuels, 2021
Nuraly Akimbekov, Ilya Digel, Gulzhamal Abdieva, Perizat Ualieva, Kuanysh Tastambek
Lignite is a fossilized mineral characterized by high moisture, high volatile matter, and lower heat content. It has a heterogeneous microstructure and is composed of a vast number of chemical species. Over the years, lignite has been increasingly used worldwide as a fuel for the generation of electricity and heat. However, lignite’s high moisture content and proneness to spontaneous combustion reduce its commercial attractiveness. Furthermore, combustion, carbonization, and gasification of immature low-rank coals constitute a serious threat to the environment due to the emission of toxic compounds [4]. On the other hand, lignite as a source of valuable humic substances (HS) could be of great interest in agriculture and environmental issues. HS are highly polar heterogeneous self-assembled supramolecular complexes and are considered a valuable natural source of three major humic fractions: humic acids (HAs), fulvic acids, and humin. The high molecular weight of most HS results from supramolecular interactions (van der Waals forces and hydrogen bonds as well as π-π- and CH-π-interactions) facilitated at neutral or alkaline pH [5]. Although all humic substances are structurally related to each other, they may differ greatly in their molecular weight as well as in the amount and distribution of particular functional groups [6].