Premium
Solubility Relationships of Zinc Associated with Acid Mine Drainage
Author(s) -
Reddy K.J.,
Sullivan Patrick J.,
Yelton Jennifer L.
Publication year - 1988
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/jeq1988.00472425001700040032x
Subject(s) - pyrite , solubility , leachate , acid mine drainage , chemistry , oil shale , environmental chemistry , zinc , humidity , inorganic chemistry , mineralogy , geology , organic chemistry , paleontology , physics , thermodynamics
Acid mine drainage, produced from the oxidation of iron‐sulfides, often contains elevated levels of dissolved Zn. To predict environmental hazards, it is important to understand the solubility relationships of Zn associated with acid mine drainage. Two eastern oil shales were leached under aerobic unsaturated environments using the humidity cell method. This study used a New Albany Shale (unweathered, 4.6% pyrite) and a Chattanooga Shale (weathered, 1.5% pyrite). The leachates from the humidity cells were filtered, and the filtrates were analyzed for total concentrations of cations and anions. From the total concentrations, ion activities were calculated, after correcting for significant solution complexes and ion pairs. The results show that the pH of the leachates decreased due to oxidation of pyrite. Furthermore, oxidation of pyrite increased the solubility of Fe 3+ and Zn 2+ in leachates. Above pH 7.00, the Zn 2+ activity was supported by Zn 2 SiO 4 (willemite) in equilibrium with measured H 4 SiO 0 4 activity. Below pH 5.00, Zn 2+ activity for both shales appeared to be saturated by ZnFe 2 O 4 (franklinite) in equilibrium with measured Fe 3+ activity. The results in this study suggest that Zn 2+ solubility in acid mine drainage, produced in an aerobic unsaturated environment, may be limited by ZnFe 2 O 4 solid phase.