Modeling acid mine drainage in waste rock dumps
- INRS, Quebec (Canada)
Acid mine drainage (AMD) results from the oxidation of sulfides present in mine wastes. The acidity generated by these reactions creates conditions under which metals can be leached and represent a threat for surface and ground waters. Even though leachate collection and neutralization are used to treat the problem, the industry is looking for methods to predict and prevent the generation of AMD at new sites and control methods for sites already producing AMD. Waste rock dumps are generally very large accumulations of barren rocks extracted from open pits to access ore bodies. These rocks contain sulfides, most commonly pyrite, and often generate AMD at rates much higher than in mine tailings which are fine grained by-products of milling operations. Numerous coupled physical processes are involved in AMD production in waste rocks. Sulfide oxidation reactions are strongly exothermic and temperatures beyond 70{degrees}C have been measured in some dumps. That heat is transfered by conduction and fluid advection. Dumps have thick partly saturated zones through which gases flow under thermal gradients and water infiltrates. Oxygen is required by the oxidation reactions and is supplied by diffusion and advection. The reaction products are carried in solution in very concentrated leachates. Numerical modeling of AMD aims to (1) provide a better understanding of the physical processes involved in AMD, (2) allow the integration of available waste rock characterization data, (3) indicate new data or studies which are required to fill the gaps in our quantitative understanding of AMD processes, and (4) supply a tool for the prediction of AMD production, taking into account the impact of control methods. These objectives can only be met through sustained research efforts. This study is part of a wider research effort which as been on-going at La Mine Doyon since 1991.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 107191
- Report Number(s):
- LBL-37200; CONF-9503110-; ON: DE95014788; TRN: 95:006737-0031
- Resource Relation:
- Conference: TOUGH 95: transport of unsaturated ground water and heat workshop, Berkeley, CA (United States), 20-22 Mar 1995; Other Information: PBD: Mar 1995; Related Information: Is Part Of Proceedings of the TOUGH Workshop `95 Lawrence Berkeley Laboratory, Berkeley, California, March 20--22, 1995; Pruess, K. [ed.]; PB: 380 p.
- Country of Publication:
- United States
- Language:
- English
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