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Role of Water in Recovery and Production of Raw Fuels
Published in Yatish T. Shah, Water for Energy and Fuel Production, 2014
While coal mining also requires significant use of water and produces acid drainage that can affect local aquifers, the large use of water in the coal industry is also in the coal preparation plants [40]. Coal preparation plant requires washing, crushing, and removal of various impurities from coal. One area where significant water is used is in the removal of inorganic sulfur (iron pyrites) from coal by the floatation process. In this process, finely pulverized coal goes through a floatation process in which iron pyrite particles are removed from coal by gravity separation due to the density difference between pyrites and coal particles. The removal of sulfur, other impurities (like ash), and metals is important for the downstream operations for coal. For example, once the coal is finely pulverized and all ash and metals are removed, coal-water slurry becomes an important fuel for combustion purposes. The subject of coal-water slurry combustion is discussed in Chapter 5. The conversion of coal to oil by direct or indirect coal liquefaction processes also uses a significant amount of water. For 50,000 barrels per stream day (BPSD), water requirement can vary from 7,300 to 10,500 gallons per minute (GPM) depending on the nature of coal. For coproduction of Fischer—Tropsch (FT) liquids plus electric power of 25,000 BPSD and 1,250 MW plant, water requirement can be 20,800 GPM [40].
New progress and sustainable development of rock mechanics and engineering in China
Published in Wang Sijing, Fu Bingjun, Li Zhongkui, st Century, 2020
In average for mining one ton of run-of-mine coal it is necessary to discharge 2t of polluted water. Pollution of water sources in the mine area due to mine water, waste water from the coal preparation plant and seepage water from the rejects bring about great danger to the environment. In some areas the residents are in water shortage because of serious pollution of the water sources, the rivers, lakes and sea. For example, coal mining in Shanxi province leads to difficulties in supplying water for living in 28 counties with a total population of 0.33 million. The Influence of coal extraction and utilization on atmospheric environment.
Assessment of coal sortability and washability using dual energy X-ray transmission system
Published in International Journal of Coal Preparation and Utilization, 2022
Yi Ran Zhang, Nawoong Yoon, Maria E. Holuszko
Washability analysis are used to predict ease of washing of any coal sample by gravity methods and is assessed from series of float-and-sink tests. At the coal preparation plant, coal is treated in various size ranges and gravity separation circuits are employed for coarse and intermediate sizes while fine coal is usually treated by flotation. In traditional float-and-sink test, the underlying principle for separation is density difference between different coal particles, hence the coal particles are grouped into a range of specific gravity from each round of float -and-sink tests (Laskowski and Walters 1987; Leonard 1979). This process can be time consuming for operations where they require quick turnaround of multiple washability results on a given day. Since the DE-XRT is able to analyze particle by particle, hence we are able to predict the ash content and specific gravity of a given particle, it should be possible to estimate the washability of a given coal sample. Once the washability data is plotted, specific gravity (SG) can be selected for separating coal particles according to their ash and the prediction of yield of coal material separated at any given density of separation, a cut point can be obtained. This will allow for prediction of the yield for a coal product of desired ash to be produced from sorting operation by XRT. If successfully validated, it can also be used in routine washbality tests at the plant.
Modeling Aleatory and Epistemic Uncertainty in Human Health Risk Assessment
Published in Cybernetics and Systems, 2020
Furthermore, pollutions may also occur from different industries, for examples the pulp and paper industry is one of the largest and most polluting industries in the world which pollutes our water, air, and soil. Mill wastewater continues to wreak havoc on surrounding ecosystems. Air discharges from pulp mills contain hormone-disrupting and carcinogenic chemicals, such as chlorinated phenols, polycyclic aromatic hydrocarbons (PAHs), and VOCs. Oil refineries are the largest industrial producers of volatile organic chemicals, or VOCs. Oil refineries also release other toxic chemicals into the air such as benzene. The oil refinery industry is the largest source of benzene emissions. Benzene affects the blood and blood organs within the body by causing the cells to function incorrectly. Workers risk exposure to a number of chemicals and unhealthy materials that are present while drilling for oil. These include crude oil, hydrogen sulfide gas, asbestos, formaldehyde, hydrochloric acid, benzene and heavy metals. Drilling for oil can also produce radioactive waste. This happens when naturally radioactive materials like stones or soil are brought to the surface during the drilling process. Radioactive waste can also be found in produced water, sludge and drilling mud. Produced water is underground water brought to the surface during the drilling process, along with the oil. It can be as much as 100 times more radioactive than water from a nuclear power plant. Workers are exposed to the radium isotopes that are released from these wastes, raising their risk of cancer. The radon gas that’s released during drilling also increases workers’ risk of lung cancer. Air pollution in coal mines is mainly due to the fugitive emission of particulate matter and gases including methane (CH4), sulfur dioxide (SO2) and oxides of nitrogen (NOx). The major source of water pollution in the coal mines is the carryover of the suspended solids in the drainage system of the mine sump water and storm water drainage. In some of the coal mines, acidic water is also found in the underground aquifers. In addition, waste water from coal preparation plant and mine water are other sources of water pollution. Fertilizer production involves the manufacture of hazardous chemicals (ammonia), strong mineral acids (sulphuric, nitric and phosphoric), oxidizing agents, etc. Cement dust contains heavy metals like nickel, cobalt, lead, chromium etc., pollutants hazardous to the biotic environment, with adverse impact for vegetation, human and animal health and ecosystems (Dutta and Ali 2012b).