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Rare earth elements in western Canadian coals

Journal Article · · Energy Sources; (United States)
OSTI ID:6041794
 [1]
  1. Univ. of Victoria, British Columbia (Canada). School of Earth and Ocean Sciences

Rare earth element (REE) were determined in an age series, Lower Cretaceous to Eocene, of seven western Canadian coals using instrumental neutron activation analysis. The coals are from three tectonic belts, namely, Insular (Suquash, Comox, and Nanaimo), Intermontane (Tulameen and Hat Creek), and Northeast Rocky Mountain (Quintette and Bullmoose). Rank ranges from lignite-subbituminous B C to medium-volatile bituminous. Chondrite-normalized patterns show enrichment of the LREE compared with HREE. Shale-normalized patterns show little differentiation with respect to shale in the Intermontane and Northeast Rocky Mountain coals, however, HREE enrichments occur in the Insular Belt deposits. High correlation coefficients with specific ash constituents in the coal indicate that the REE are associated with clay minerals, heavy minerals, and calcite. Preferential occurrence of the HREE or LREE in different mineral phases occurs in, for example, the Comox and Tulameen deposits. Vertical distributions of the REE primarily reflect variations in ash content of the coal-bearing sections, however, some variations did occur. In the Tulameen deposit the LREE are progressively more depleted toward the base of the section, both in coal and interbedded shale. Considerable variability exists in REE concentrations and shale-normalized patterns from coals worldwide. In general Cretaceous coals appear to be more HREE enriched than Tertiary or Carboniferous coals. REE concentrations in the Canadian coals examined do not reflect age or rank of the deposits. Rather, source rock variations, modified by weathering, and depositional/diagenetic histories of the deposits, are thought to control the REE variations observed.

OSTI ID:
6041794
Journal Information:
Energy Sources; (United States), Journal Name: Energy Sources; (United States) Vol. 15:4; ISSN 0090-8312; ISSN EGYSAO
Country of Publication:
United States
Language:
English