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Reactivity of AN-FO With Pyrite-containing Weathering Products.

Miron Y; Ruhe TC; Watson RW
NTIS: PB 80-101942 :24 pages
Ammonium nitrate-fuel oil (AN-FO) mixtures are used as blasting agents in mining pyrite-bearing ores. The temperature of these ores can increase by the continuous, though at times slow, oxidation weathering of the pyrites. At elevated temperatures, AN-FO reacts exothermally with pyrite, and the reaction becomes self-sustained at 120 deg c +/- 10 deg c. The Bureau of Mines has conducted an investigation to determine the reactivity of mixtures of AN-FO with pyrite containing ferrous sulfate. The results of tests in a heated vessel simulating a hot borehole demonstrate that small amounts of ferrous sulfate, a major product of pyrite weathering, initiate a self-sustained exothermic reaction with AN-FO at 80 deg c. Five percent by weight of urea was found sufficient to prevent a reaction among the three ingredients, at least within the limits of the test, which reached 180 deg c. Smaller amounts of urea and of potassium oxalate slowed down the reaction and delayed its onset to higher temperatures, but did not prevent it.
Publication Date
Document Type
IH; Report of Investigations
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
RI 8373
NIOSH Division
Source Name
NTIS: PB 80-101942
Page last reviewed: October 29, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division