Suppression of pyrite oxidation by iron 8-hydroxyquinoline.
One of the important approaches to prevent pyrite (FeS(2)) oxidation and subsequent formation of acid mine drainage (AMD) is to create a surface coating on pyrite. In this study, a coating of iron 8-hydroxyquinoline was formed by leaching pyrite with a 0.10 M H(2)O(2)/0.0034 M 8-hydroxyquinoline solution; stability of the coated pyrite was tested under various pH and temperature conditions. The results showed that iron 8-hydroxyquinoline coating could significantly suppress further pyrite oxidation by both chemical (H(2)O(2)) and biological ( e.g., Thiobacillus ferrooxidans) processes. At pH from 3.0 to 5.0 and temperature from 10-40 degrees C, the amount of SO(4)(2-) leached out by 0.10 M H(2)O(2) from the coated pyrite samples was 54.8-70.1% less than that from the uncoated controls. The oxidation of pyrite followed a pseudo-zero-order kinetics under the constant concentration of H(2)O(2). In the presence of microorganisms, sulfate leached out of the uncoated pyrite in 1 year accounted for 5.32% of the total pyrite in the system, with a concurrent pH drop to 2.35 under the ambient room temperatures. In contrast, the amount leached out from the coated samples was only 0.15% of the total pyrite and the final pH was 5.48. Thus, the coating decreased the leachability of pyrite by 97% in the inoculated systems. In comparison to the more widely studied iron phosphate coating, the advantage of iron 8-hydroxyquinoline coating was that it inhibited both chemical and biological pyrite oxidation, whereas iron phosphate coating could only inhibit chemical pyrite oxidation.
College of Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
Y
Y
Lan
X
X
Huang
B
B
Deng
D004867:Equipment Design; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D058085:Iron Compounds / Q000737:chemistry*; D008906:Mining; D010084:Oxidation-Reduction; D015125:Oxyquinoline / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry* / Q000378:metabolism; D013855:Thiobacillus / Q000502:physiology; D014876:Water Pollution / Q000517:prevention & control
D058085:Iron Compounds; D013440:Sulfides; C011342:pyrite; D015125:Oxyquinoline; D007501:Iron