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Removal of Pyrite from Coal by Dry Separation Methods.

Abel-WT; Zulkoski-M; Brady-GA; Eckerd-JW
NTIS: PB 221 627 :26 pages
The difficulties associated with wet-processing fine size coal led the Bureau of Mines to investigate a dry process for removing pyrite from coal pulverized to powerplant fineness. The dry process that was investigated consists of two cleaning steps: first, centrifugal separation is used to remove a fine, pyrite-depleted portion as a product; second, the remaining coarser, pyrite-enriched portion is taken to electrostatic separation in which pyrite is concentrated and rejected. Ball milling and hardgrove milling were used to pulverize the coal. Three coals from the Pittsburgh seam were treated by the dry-removal process. Over 55 percent of the pyrite, which amounted to 70 percent of the available pyrite, was removed in a reject of 10 to 20 percent from one of the coals. Similar treatment of the other two coals removed about 35 to 50 percent of the pyritic sulfur, which amounted to about 70 percent of the available pyritic sulfur from these coals. Both centrifugal and electrostatic separations were more efficient when pyrite particles were as large as possible. Separation efficiency was improved by confining the particle size of the feed to a relatively narrow range and by avoiding excessive amounts (more than 10 percent) of dust in the electrostatic range. The removal efficiency was increased with the use of stage grinding.
Publication Date
Document Type
IH; Report of Investigation;
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
RI 7732
NIOSH Division
Source Name
NTIS: PB 221 627