نتایج جستجو برای: coal
تعداد نتایج: 31950 فیلتر نتایج به سال:
the removal ofxylenol orange from aqueous solution onto the coal ash was investigated at room temperature. the results show that the adsorption capacity of xylenol orange increased as the adsorption time increased and then equilibrium established after 30 min adsorption time. the results obtained revealed that the coal ash removed about 80 % of xylenol orange from the aqueous solution within 40...
The permeability of coal is a critical parameter in estimating the performance of coal reservoirs. Darcy’s law describes the flow pattern that the permeability has a linear relationship with the flow velocity. However, the stress induced deformation and damage can significantly influence the gas flow pattern and permeability of coal. Coals from Songzao coalfield in Chongqing, southwest China we...
This paper established a system dynamics model of energy saving and emission reduction in coal mining area, as well as conducted simulation of different development plans, based on the analysis of energy saving and emission reduction factor of coal production links, of the complex structure of energy saving and emission reduction system in coal mining area, and of the dynamic feed-back mechanis...
Coal combustion is the primary anthropogenic source of atmospheric iodine, which has important environmental and health effects. The iodine distribution in Chinese coals and the atmospheric iodine emission factors of coal-fired boilers are studied to estimate the iodine atmospheric flux from coal combustion in China from 1995 to 2009. The national average iodine content weighted by coal yield f...
Based on differences in the permittivity of coal and limestone rock, a resonant cavity measurement technique is presented for the rapid determination of the proportions of coal and limestone in powdered mixtures. The ratio of the resonant frequency shift and the change in the transmission factor when mixed coal and limestone samples are inserted into the cavity provides a means for estimating t...
The economic and stable operation was affected seriously by coal quality disturbance for power plants. Based on model analysis, influence of the disturbance can be considered as gain change of control system. Power capability coefficient of coal was constructed to inhibit it. Accuracy of the coefficient was verified by operating data. Then coal quality disturbance free system based on gain sche...
Due to the abundance of the non-coking coal and limitations as well as the high costs of the natural gas, the present study examined the direct reduction of hematite (iron oxide) ore in the temperature range of 800-1000 °C by the non-coking coal volatiles. Approximately, 74.9% of the total amounts of volatiles and gases exit the coal up to 800°C. The onset temperature to exit volatiles from the...
Increasing the production rate and minimizing the related costs, while optimizing the safety measures, are nowadays’ most important tasks in the mining industry. To these ends, mechanization of mines could be applied, which can result in significant cost reductions and higher levels of profitability for underground mines. The potential of a coal mine mechanization depends on some important fact...
BACKGROUND Nearly 4.3 million deaths worldwide were attributable to exposure to household air pollution in 2012. However, household coal use remains widespread. OBJECTIVES We investigated the association of cooking coal and all-cause and cause-specific mortality in a prospective cohort of primarily never-smoking women in Shanghai, China. METHODS A cohort of 74,941 women were followed from 1...
Ultrasound can be used both simultaneously or as a pretreatment technique for flotation to produce higher combustible recoveries, higher heat values, and lower ash data from raw hard coals. The recent research works have indicated that modifying coal surfaces, especially physical surface cleaning with the help of the cavitation process created by power ultrasound at certain frequency and time i...
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