Metalliferous Coals of Cretaceous Age: A Review

Abstract

Critical elements in coal and coal-bearing sequences (e.g., Li, Sc, V, Ga, Ge, Se, Y and rare earth elements, Zr, Nb, Au, Ag, platinum group elements, Re, and U) have attracted great attention because their concentrations in some cases may be comparable to those of conventional ore deposits. The enrichment of critical elements in coals, particularly those of Carboniferous-Permian and Cenozoic ages, have generally been attributed to within-plate (plume-related) volcanism and associated hydrothermal activity. However, Cretaceous coals are not commonly rich in critical elements, with the exception of some (e.g., Ge and U) in localised areas. This paper globally reviewed metalliferous coals from Siberia, the Russian Far East, Mongolia, South America, the United States and Mexico, Canada (Alberta and British Columbia), China, Africa, and Australasia (Victoria, Queensland, New South Wales, South Australia, Northern Territory, New Zealand, Nelson, West Coast, Canterbury, Otago, and Southland). The world-class Ge-U or Ge deposits in North China, Mongolia, and Siberia are the only commercially significant representatives of the Cretaceous metalliferous coals, which are related to bio-chemical reduction of oxidized meteoric, hydrothermal, or sea waters by organic matter of the peat bogs. The common Cretaceous coals worldwide are generally not rich in critical elements because intensive igneous activity led to extensive acidification of terrestrial and marine waters, which are responsible for the low coal metallogenesis during the Cretaceous period, especially the Early Cretaceous time.

Trace Elements in Pernik Sub-Bituminous Coals and Their Combustion Products Derived from the Republika Thermal Power Station, Bulgaria

“…They were taken from (1) a network of points at accessible locations in DP and from CPP warehouses; (2) the moving conveyor belts of the CPP at a certain time interval; and (3) the TPS director's average control samples used in the TPS laboratory in monitoring the quality of fuel and waste products. The samples include (1) run-of-mine sub-bituminous coal (RC); (2) feed coal (FC); (3) high-grade coal (HGC); (4) coal slurry (CS); (5) associated host rock (AR); (6) fly ash (FA); (7) bottom ash (BA); and (8) mixed material from the coal beneficiation and burning processes, which were taken from the disposal pond (DP). The samples were dried at room temperature and stored in plastic bags.…”

“…In the processes of coal beneficiation and coal combustion in thermoelectric power stations (TPSs), several major waste products are generated, namely coal slurry, associated host rocks, bottom ash, and fly ash. It is well known that the detailed knowledge about the mineralogy and inorganic chemistry of these products has important fundamental, technological [1][2][3][4][5][6][7][8][9], and ecological [10][11][12][13][14][15] significance. Therefore, valuable information on the inorganic composition of coals and their combustion products has been summarized in several monographs [16][17][18][19].…”

Geochemical Characteristics of Critical Metal Elements in the No. 9 Coal Seam from the Xinyuan Mine, Northern Qinshui Coalfield, Shanxi Province, China

“…The Qinshui coalfield is located between the Taiyue Mountain and the middle southern section of the Taihang Mountain in the southeast of Shanxi Province. The coal-bearing area of the Qinshui coalfield is 32,084 km 2 . The main coal-bearing strata are the Carboniferous Taiyuan formation and the Permian Shanxi formation.…”

“…Critical metals and mineral resources play an irreplaceable and important role in new materials, new energy, information technology, and the aerospace industry [1]. As one of the main fossil fuels globally, coal can be enriched with a variety of beneficial elements, including critical metal elements (e.g., Li, Sc, V, Ga, Ge, Se, Y and rare earth elements, Zr, Nb, Au, Ag, and platinum group elements, Re, and U [2]), in specific geological conditions [2][3][4], and can form 'coal-hosted rare metal deposits' or 'metalliferous coal' [5,6].…”

The Discrepancy between Coal Ash from Muffle, Circulating Fluidized Bed (CFB), and Pulverized Coal (PC) Furnaces, with a Focus on the Recovery of Iron and Rare Earth Elements

“…Coal ash, as an artificial metallic mineral deposit, is a promising resource of Al, Fe, Li, Ga, and so on [ 13 , 14 ]. Among various metals, rare earth elements recovery from coal ash is impressive due to the “Rare earth Program” by the Department of Energy, the U.S.…”