Rates of iron sulfide oxidation in coal spoil suspensions

V. P. Evangelou, J. H. Grove, F. D. Rawlings

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


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 CaCO3 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 CaCO3 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 CaCO3 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.

Original languageEnglish
Pages (from-to)91-94
Number of pages4
JournalJournal of Environmental Quality
Issue number1
StatePublished - 1985

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution
  • Management, Monitoring, Policy and Law


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