U.S. Geological Survey coal quality (COALQUAL) database: Version 2.0

Bragg, Linda J.; Oman, J.K.; Tewalt, Susan J.; Oman, C.L.; Rega, N.H.; Washington, P.M.; Finkelman, Robert B.

doi:10.3133/ofr97134

Cited by 90 publications

(68 citation statements)

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“…However, the utilities, in contracting for the coal, did specify that the Fire Clay should constitute the majority of blend, but they had less control of the coal and mine selection process than was present for the Mardon and Hower [3] study. The feed coal REY concentrations are lower than published REY values for the Fire Clay coal (for example, the average Fire Clay REE and REY in Table 1 from Bragg et al [4] and Table 2 values from Hower et al [2] and Mardon and Hower [3]). Caution must be exercised in comparing geologic samples to the mined, beneficiated (or not beneficiated), and shipped product.…”

Section: Resultsmentioning

confidence: 44%

“…In some cases where the tonstein is not present, the coal is still enriched in REY [3]. Comparing average ash-basis REYs from five major coals (Table 1, after Bragg et al [4]), it can be seen that the Fire Clay coal and its correlatives have a higher total REY than the other coals. Table 1.…”

Section: Introductionmentioning

confidence: 97%

“…Averages (ash-basis ppm) of rare earth elements and yttrium for five major eastern Kentucky coals. Based on data compiled by [4]. The Clintwood Gd average contains one value of 173 ppm, far higher than the other Gd values.…”

Section: Introductionmentioning

confidence: 99%

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Notes on the Potential for the Concentration of Rare Earth Elements and Yttrium in Coal Combustion Fly Ash

et al. 2015

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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. OPEN ACCESSMinerals 2015, 5 357

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Section: Resultsmentioning

confidence: 44%

Section: Introductionmentioning

confidence: 97%

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Notes on the Potential for the Concentration of Rare Earth Elements and Yttrium in Coal Combustion Fly Ash

et al. 2015

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“…The data that were used to examine the proposed approaches were obtained from the U.S. Geological Survey Coal Quality (COALQUAL) database, open file report 97-134 (Bragg et al, 2009). Samples with more than 50% ash and samples that had a proximate analysis and/or an ultimate analysis different from 100% were excluded from the database.…”

Section: Experimental Datamentioning

confidence: 99%

Adaptive Neuro-Fuzzy Inference System Prediction of Calorific Value Based on the Analysis of U.S. Coals

Rafezi¹,

Jorjani²,

Karimi³

2011

Artificial Neural Networks - Industrial and Control Engineering Applications

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“…These results are consistent with the high pyrite content (2.7%, calculated from pyritic-S) of the Ohio coal relative to the other samples (North Dakota = 0.53%; Wyodak = 0.09%). The Hg content of the Ohio coal (0.18 ppm, determined by CVAA), is about average for over 7,000 U.S. coals in the USGS COALQUAL database [1]. Hg contents of the Wyodak (0.13 ppm) and North Dakota (0.08) samples are lower, but this distinction is lessened or reversed for low rank coals if they are considered on an equal-energy basis [2].…”

Section: Analysis Of Whole Coalsmentioning

confidence: 99%