Scholarly Works, Mining and Minerals Engineering
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Browsing Scholarly Works, Mining and Minerals Engineering by Subject "0403 Geology"
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- The Effect of Conditioning on the Flotation of Pyrrhotite in the Presence of ChloriteChen, Yanfei; Shi, Qing; Feng, Qiming; Lu, Yiping; Zhang, Wencai (MDPI, 2017-07-20)The influence of conditioning on the flotation of pyrrhotite in the presence of chlorite was investigated through flotation tests, sedimentation tests, and X-ray photoelectron spectroscopy (XPS) analysis. The flotation results show that chlorite slimes dramatically impair the flotation of pyrrhotite. Sedimentation and flotation tests reveal that conditioning can effectively remove chlorite slimes from pyrrhotite surfaces, resulting in an enhanced flotation recovery of pyrrhotite. When mixed minerals were conditioned under the natural atmosphere, a faster conditioning speed and longer conditioning time decreased the flotation recovery of pyrrhotite. However, when mixed minerals were conditioned under a nitrogen atmosphere, a more intensive conditioning process provided better flotation results. XPS analyses illustrate that a faster conditioning speed and longer conditioning time under the natural atmosphere accelerates the oxidation of pyrrhotite, leading to a decrease in the flotation recovery of pyrrhotite.
- Notes on the Potential for the Concentration of Rare Earth Elements and Yttrium in Coal Combustion Fly AshHower, James; Groppo, John; Henke, Kevin; Hood, Madison; Eble, Cortland; Honaker, Rick; Zhang, Wencai; Qian, Dali (MDPI, 2015-06-23)Certain Central Appalachian coals, most notably the Fire Clay coal with a REY-enriched volcanic ash fall tonstein, are known to be enriched in rare earth elements. The Fire Clay tonstein has a greater contribution to the total coal + parting REY than would be inferred from its thickness, accounting for about 20%–35% of the REY in the coal + parting sequence. Underground mining, in particular, might include roof and floor rock and the within-seam partings in the mined product. Beneficiation, necessary to meet utility specifications, will remove some of the REY from the delivered product. In at least one previously published example, even though the tonstein was not present in the Fire Clay coal, the coal was enriched in REY. In this case, as well as mines that ship run-of-mine products to the utility, the shipped REY content should be virtually the same as for the mined coal. At the power plant, however, the delivered coal will be pulverized, generally accompanied by the elimination of some of the harder rock, before it is fired into the boiler. Overall, there are a wide range of variables between the geologic sample at the mine and the power plant, any or all of which could impact the concentration of REY or other critical materials in the coal combustion products.
- Particle size and mineralogy distributions in respirable dust samples from 25 US underground coal minesSarver, Emily A.; Keles, Cigdem; Ghaychi Afrouz, Setareh (Elsevier, 2021-11-01)Detailed characterization of respirable coal mine dust is critical to understanding occupational health outcomes, as well as improving exposure monitoring and dust controls in mines. However, data on characteristics such as particle size and mineralogy are still scarce, and there are virtually no datasets available that allow direct comparisons across many mines. Following up on a previous effort to characterize dust from eight underground mines in the Appalachian region of the United States, the current study expands the dataset to cover a total of 25 mines across the country. A total of 171 respirable dust samples were collected in standard locations of each mine and analyzed by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Results demonstrate that significant differences in particle size and mineralogy distributions exist both within and between mines based on sampling location, mine region and/or mining method–and characteristics can be indicative of dust sources. In locations nearby to production or roof bolting, the respirable dust was clearly sourced from the mine strata. Interestingly, in the production location rock-strata sourced dust appeared to be inordinately abundant relative to the actual coal and rock strata heights being mined during sampling. With respect to particle size, diesel particulates and coal dust were generally found to be finer than mineral dust; and mineral dust likely sourced from the rock strata in the mine was finer than that associated with rock dusting products. On average, when considering all particles analyzed between 100 and 10,000 nm, results indicate that about 75% are in the submicron range, however these particles are estimated to account for only about 6% of the mass.