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.
Lan
Y
Y
College of Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
Huang
X
X
Deng
B
B
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