Rare earth elements in superhigh-organic-sulfur Raša coal ash (Croatia)

Resources of critical metals in coal-bearing sequences in China: Enrichment types and distribution

“…特别是美国, 自2014年以来, 对煤中稀土元 素的研究涉及的部门之广、立项速度之快、资金投入 之多, 非常罕见 [6~11] . 近年来, 欧洲国家 [12,13] 、俄罗 斯 [14~17] 、南非 [18] 、中国 [19~22] . 煤型硒矿床和钒矿床主要赋存在 石煤中 [4,5] .…”

Concentrating rare earth elements in brown coal humic acids by mechanochemical treatment

“…42 The REE content in y ash higher than 1000 g per ton is currently considered a quite high content that is of economic importance. 43,44 The organic phase bound form of REE opens up various possibilities for their recovery, in addition to the usual ashing: isolation under controlled heating and combustion, 45,46 biosorption 5,47,48 and more specic leaching methods. 4…”

Geochemical Occurrence of Rare Earth Elements in Mining Waste and Mine Water: A Review

“…The following four genetic types of REY accumulation in coal are identified [3]: (a) the terrigenous type, with REY input by the surface waters; (b) the tuffaceous type, connected with falling and leaching of acid and alkaline volcanic ash; (c) the infiltrational or meteoric groundwater-driven type and (d) the hydrothermal type, connected with the circulation of deep hydrothermal fluids [17]. The influence of hydrothermal solutions leads to sulphur and REY enrichment of the primary coal in the Rasa coal basin, Croatia [18]. The REY in coals are hosted within fine-grained authigenic minerals (REY-bearing aluminum phosphates and sulphates of the alunite group, and water-bearing phosphates and carbonates) and organic compounds.…”