The passivation of pyrrhotite by surface coating

• Published in: Chemosphere (Oxford) Vol. 61; no. 5; pp. 659 - 667
• Main Authors: Cai, Mei-Fang, Dang, Zhi, Chen, Yu-Wei, Belzile, Nelson
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-11-2005; Elsevier
• Subjects: Acidithiobacillus - metabolism; Acidithiobacillus ferrooxidans; Air; Applied sciences; Biological and physicochemical phenomena; Chlorides; Decontamination. Miscellaneous; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Ferric Compounds - chemistry; Industrial Waste; Iron - analysis; Mining; Natural water pollution; Oxidation; Oxidation-Reduction; Passivation; Pollution; Pollution, environment geology; Pyrrhotite; Soil and sediments pollution; Sulfates - analysis; Sulfides - chemistry; Trientine - chemistry; Triethylenetetramine (TETA); Waste Management - methods; Water treatment and pollution; Oxidation; Triethylenetetramine (TETA); Pyrrhotite; Passivation; Reaction inhibitor; Microbial activity; Pollution control; Pollution prevention; Iron sulfide; Soil pollution; Coatings; Surface treatment; Biogeochemistry; Bacteria; TETA; Water pollution; Acid mine drainage
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2005.03.032

The potential of triethylenetetramine (TETA) to inhibit the oxidation of three pyrrhotites, Garson, McCreedy and Po-97 has been studied systematically and confirmed by comparing the release of Fe and
SO
4
2
-
from samples with and without coating treatment. Each sample, original or coated by TETA, was exposed to oxygen, 1
×
10
−3
M FeCl
3, and
Acidithiobacillus ferrooxidans, respectively, for specific oxidation periods. Both abiotic and biotic oxidation of samples treated by this passivating agent has been reduced significantly in this study. Under the aerobic condition, lower concentrations of ferric, total Fe or
SO
4
2
-
were obtained from the coated samples than those from the uncoated samples. In the presence of 1
×
10
−3
M FeCl
3 at 30
°C, TETA was able to reduce oxidation rates of Garson, McCreedy and Po-97 by 83%, 79%, and 81% (based on Fe release), respectively. A higher pH, lower Eh, and lower concentrations of total Fe and
SO
4
2
-
were also observed in the biotic oxidation of coated Garson by
Acidithiobacillus ferrooxidans. The protection of pyrrhotite surface from oxidant attack by TETA barrier and the alkaline property of this coating agent can be used to interpret the inhibition of oxidation.