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Rates of Iron Sulfide Oxidation in Coal Spoil Suspensions
Author(s) -
Evangelou V. P.,
Grove J. H.,
Rawlings F. D.
Publication year - 1985
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1985.00472425001400010018x
Subject(s) - dissolution , chemistry , pyrite , particle size , sulfate , reagent , sulfide , fraction (chemistry) , suspension (topology) , inorganic chemistry , toluene , decomposition , iron sulfide , sulfur , nuclear chemistry , mineralogy , chromatography , organic chemistry , mathematics , homotopy , pure mathematics
Rates of pyritic coal spoil oxidation were studied in water suspensions of each of two particle‐size fractions (< 0.5 mm and 0.5–2 mm). The treatments on each of the size fractions included liming with reagent grade CaCO 3 at rates of 0, 14.4, and 28.8 g kg −1 . In another treatment, toluene was added to unlimed suspensions to inhibit microbial growth. The greatest rate of salt formation (taken as a measure of pyrite oxidation) was associated with the larger size fraction. Toluene suppressed the oxidation‐dissolution rate, suggesting a microbial role in pyrite oxidation in these systems. The application of CaCO 3 at 14.4 g kg −1 spoil to the 0.5‐ to 2.0‐mm size fraction enhanced the oxidation‐dissolution process during the initial phase of the reaction (0–100 min). When the larger size fraction was amended with CaCO 3 at a rate of 28.8 g kg −1 , three rates of oxidation‐dissolution were apparent. The first rate was attributed to dissolution of indigenous sulfate salts. The second rate was attributed to oxidation of a more reactive pyrite fraction than that described by the third rate (slowest rate). This last rate was attributed to a nonmicrobial oxidation pathway due to the higher pH values observed in the suspension.