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In Situ Coating Formation on Apatite Particles When Leached Using H2so4 in the Presence of Methanol.

Authors
Swanton-RG; Wilemon-GM
Source
SME Preprint 91-29 1991 :8 pages
Link
NIOSHTIC No.
10009146
Abstract
The U.S. Bureau of Mines is investigating the leaching of phosphate values from Florida phosphatic clay wastes using sulfuric acid (h2so4) as the leaching agent and methanol as the solvent. Acid- alcohol leaching studies were done using pure crystalline apatite to investigate potential causes for low extractions. It was found that a barrier layer formed on the surface of the apatite. Initial discovery of the barrier layer was made by analyzing pure apatite samples before and after leaching using an optical microscope. Subsequent fourier transform infrared (ft-ir) analyses proved the coating was calcium sulfate hemihydrate (caso4.1/2H20) and that unreacted apatite existed beneath the coating. Scanning electron microscope photographs depict the caso4.1/2H2o morphology as long slender crystals adhering to the apatite surface. It was also shown that grinding the leached tailings and leaching again in the h2so4- methanol system resulted in additional phosphate extraction.
Publication Date
19910101
Document Type
OP;
Fiscal Year
1991
NTIS Accession No.
NTIS Price
Identifying No.
OP 89-91
NIOSH Division
TURC;
Source Name
SME Preprint 91-29, 1991, 8 PP.
State
FL;
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