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Removal of magnesium impurities from phosphate rock concentrates.

Authors
Rule AR; Gruzensky WG; Stickney WA
Source
Albany, OR: U.S. Department of the Interior, Bureau of Mines, RI 7362, 1970 Mar; :1-12
Link
NIOSHTIC No.
10008963
Abstract
Laboratory tests were conducted to study removal of magnesium impurities from western phosphate rock concentrates by selective leaching. The systems evaluated included leaching with dilute sulfuric acid, leaching with ammonium sulfate, and leaching in an aqueous medium with sulfur dioxide gas. Set standards for the magnesium impurity level of phosphate rock concentrates are not available, but industrial practice has indicated that magnesium in excess of 0.3 percent MgO causes problems in phosphoric acid manufacture. Removal of magnesium was accomplished with all three systems. With dilute H2SO4 the magnesium level was reduced to less than 0.1 percent MgO with an accompanying P2O5 loss of 6 percent. Magnesium oxide levels from 0.3 to 0.2 percent were obtainable with ammonium sulfate. However, the system requires concentrate roasting at temperatures of 900 deg. C or higher, heated pulps (100 deg. C), and large quantities of ammonium sulfate. Selective leaching was obtained using SO2 gas in an aqueous concentrate slurry. Magnesium oxide content was reduced to less than 0.1 percent without loss of phosphate.
Publication Date
19700301
Document Type
IH; Report of Investigations
Fiscal Year
1970
NTIS Accession No.
PB-190970
NTIS Price
A03
Identifying No.
RI-7362
NIOSH Division
ALRC
Source Name
Albany, OR: U.S. Department of the Interior, Bureau of Mines, RI 7362
State
OR
Page last reviewed: June 7, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division