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Kuyucak, N. (1998). Mining, the Environment and the Treatment of Mine Effluents. Int. J. Environ. Pollut., 10(2), 315–325.
Abstract: The environmental impact of mining on the ecosystem, including land, water and air, has become an unavoidable reality. Guidelines and regulations have been promulgated to protect the environment throughout mining activities from start-up to site decommissioning. In particular, the occurrence of acid mine drainage (AMD), due to oxidation of sulfide mineral wastes, has become the major area of concern to many mining industries during operations and after site decommissioning. AMD is characterized by high acidity and a high concentration of sulfates and dissolved metals. If it cannot be prevented or controlled, it must be treated to eliminate acidity, and reduce heavy metals and suspended solids before release to the environment. This paper discusses conventional and new methods used for the treatment of mine effluents, in particular the treatment of AMD.
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Kuyucak, N. (2001). Acid mine drainage; treatment options for mining effluents. Mining Environmental Management, 9(2), 12–15.
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Kuyucak, N., Lindvall, M., Rufo Serrano, J. A., & Oliva, A. F. (1999). (R. Fernández Rubio, Ed.). Mine, Water & Environment. Ii: International Mine Water Association.
Abstract: Lime neutralization is a frequently used method in the mining industry for the treatment of acid waters. These waters contain metal ions such as zinc, manganese, copper, cadmium, lead, etc. The conventional, straight lime neutralization technology generates a Low Density Sludge (LDS) having only 1-2% solids content. This creates sludge disposal difficulties, and results in the loss of potentially large quantities of recovered water, which in turn increases the demand for fresh water requirements for mining/milling activities. The High Density Sludge (HDS) process, on the other hand, is the state-of-the-art technology in North America. It generates a dense sludge with less volume and better particulate properties. Furthermore, the typical gelatinous nature of the sludge changes to a granulated, sand-like texture. Boliden Apirsa, S.L. investigated the feasibility of an HDS process to increase the treatment capacity of their existing plant, and resolve the issues associated with the LDS process for their Los Frailes project. The project required, given that the production of ore was going to be doubled, a significant increase in water was needed without altering the water reservoir sitting north of the concentrator. In addition, the final effluent quality was a priority issue. First, a pilot-scale study was undertaken in 1996, and parameters critical to the design and performance of the process were determined. The results showed that the HDS process could significantly improve the sludge characteristics by increasing the solids fraction from 1.5 to 12.0%, thereby decreasing the sludge volume to be disposed to the tailings ponds by a factor of 10. A full-scale, HDS lime neutralization treatment plant for an average flow rate of 1500 m3/hr was designed and was commissioned in early 1998 in collaboration with Colder Associates, Ottawa, Canada. So far, the full-scale treatment plant has been generating a sludge with more than 30% solids content, exceeding its target value of 12% solids. It produces excellent effluent quality, and scaling in the handling equipment is virtually eliminated. The sludge has dense, easily settable granular particles rather than fluffy flocs, yet has low viscosity that facilitates its unassisted gravity flow. The process has resulted in an increase in the treated water volume. The rate of lime consumption per unit volume of water treated also decreased. The process principles and the steps taken in process development will be discussed and the results obtained to date will be summarized in this communication.
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Mitchell, P., & Wheaton, A. (1999). From environmental burden to natural resource; new reagents for cost-effective treatment of, and metal recovery from, acid rock drainage. In D. E. Goldsack, N. Belzile, P. Yearwood, & G. J. Hall (Eds.), Sudbury '99; Mining and the environment II; Conference proceedings.
Abstract: Acid rock drainage remains the greatest environmental issue faced by the mining sector and as the new millennium approaches, low capital/operating cost treatments remain elusive. Therefore as part of an ongoing process to develop a leading edge, innovative and cost-effective approach, pilot trials were conducted by KEECO in collaboration with the New Bunker Hill Mining Company on a substantial and problematic metal-contaminated acid flow, emanating from underground workings at the Bunker Hill Mine, Idaho. The aims of the work were fourfold. First to assess the capacity of KEECO's unique Silica Micro Encapsulation (SME) reagents and associated dosing systems to cost-effectively decontaminate the acid flow to stringent standards set by the U.S. Environmental Protection Agency (USEPA), where alternative and standard technologies had failed. Second, to demonstrate that treatment using a compact system suitable for underground installation. Third, to demonstrate that the treatment sludge had enhanced chemical stability in absolute terms and relative to standard approaches. Fourth, to examine the potential for resource recovery via sequential precipitation. Although the focus to date has been the development of a cost-effective treatment technology, the latter aim was considered essential in light of the growing pressure on all industrial sectors to develop tools for environmentally sustainable economic growth and the growing demands of stakeholders for improved resource usage and recycling. Two phases of work were undertaken: a laboratory-based scoping exercise followed by installation within the mine workings of a compact reagent delivery/shear mixing unit capable of treating the full flow of 31 L s (super -1) . At a dose rate of 2.0 g L (super -1) (equivalent to a final treated water pH range of 7-9), the SME reagent KB-1 reduced metal concentrations to levels approaching the U.S. Drinking Water Standards, which no other treatment piloted at the site had achieved. Based on the USEPA's Toxicity Characteristic Leaching Procedure, the sludge arising from the treatment was classified as non-hazardous. Operating costs compared favourably with those of lime use, while estimated capital costs were considerably lower due to the compact nature of the reagent delivery system and the rapid settling characteristics of the treatment sediment. Resource recovery was attempted using a two-stage selective precipitation approach. The first stage involved pH adjustment to 5.5 (by addition of 1.5 g L (super -1) of KB-1) to produce a sludge enriched in aluminium, iron and manganese, with lesser amounts of arsenic, nickel, lead and zinc. Further KB-1 addition to a total of 2.1 g L (super -1) generated sludge enriched in zinc (33% by dry weight), demonstrating that resource recovery is theoretically feasible. Further work on downstream processing is required, although it is considered that the most likely route for zinc metal recovery will be high temperature/pressure due to the chemically inert nature of the zinc-rich sediment.
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Nakazawa, H. (2006). Treatment of acid mine drainage containing iron ions and arsenic for utilization of the sludge. Sohn International Symposium Advanced Processing of Metals and Materials, Vol 9, , 373–381.
Abstract: An acid mine drainage in abandoned Horobetsu mine in Hokkaido, Japan, contains arsenic and iron ions; total arsenic ca.10ppm, As(III) ca. 8.5ppm, total iron 379ppm, ferrous iron 266ppm, pH1.8. Arsenic occurs mostly as arsenite (As (III)) or arsenate (As (V)) in natural water. As(III) is more difficult to be remove than As(V), and it is necessary to oxidize As(III) to As(V) for effective removal. 5mL of the mine drainage or its filtrate through the membrane filter (pore size 0.45 mu m) were added to arsenite solutions (pH1.8) with the concentration of 5ppm. After the incubation of 30 days, As(III) was oxidized completely with the addition of the mine drainage while the oxidation did not occur with the addition of filtrate, indicating the microbial oxidation of As(III). In this paper, we have investigated the microbial oxidation of As(III) in acid water below pH2.0.
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