Design and construction of the Montana Tunnels tailings disposal facility

Abstract Construction of the first stage of the tailings disposal facility for the Montana Tunnels Project was completed in October 1986. The project is located 37 km south of Helena, Montana, and involves mining of 42 million tons of weathered diatreme ore at a rate or 13 500 tpd to produce a gold/silver dore, as well as lead and zinc concentrates. The tailings disposal facility for the project includes a fully drained tailings impoundment for storage ofthe tailings solids, and a process water pond for storage of all decanted water prior to recyling to the mill. The over-all facility is designed to achieve the basic objectives of minimizing seepage to the environment in the short- and long-term, and achieving a fully drained stable tailings mass suitable for immediate reclamation on completion of mining. Specific features of the design include a soil bentonite seal and drainage system within the tailings basin, a free draining embankment with a design flow-through capacity of 4000 USgpm and an ultimate height of 230 ft (70 m), and a soil bentonite lined make-up water pond with a capacity of 420 acre-feet (530 000 m3). The tailings will be discharged in a rotational sequence through multiple spigot offtakes to achieve a thin-layer low-energy laminar flow. This 'sub-aerial' deposition results in higher stored densities and maximizes liquid-solid separation on the tailings beaches. The over-all design played a major role in the successful permitting of the project, and was significantly cheaper than a conventional wet disposal system, with overall unit costs for tailings disposal of less than US$0.36 per ton.
This paper outlines the site characteristics and the tailings material properties and their influence on the design. Extensive use was made of naturally occurring free draining materials as well as bentonite modified soil liners within the tailings basin, embankment and retention ponds. General construction procedures for the various components are described, as well as on-going construction requirements utilizing materials from the open pit. Finally, the over-all costs and unit costs for tailings disposal are presented.
Keywords: Mineral processing, Tailings, Equipment design, Montana Tunnels Project.
Full Access to Technical Paper
PDF version for $20.00
Search
Sort By:  Relevance
Showing results 1 - 5
Text
Summary: This article is based on a paper presented by Jim Scott at the 1988 annual convention of the Prospectors and Developers Association of Canada. The paper suggests a number of factors that might be taken into account in negotiating royalty terms.
Publication: CIM Bulletin
Author(s): ROBERT B. PARSONS
Issue: 919
Volume: 81
Year: 1988
Text
Summary: Nineteen streams in the copper and zinc flotation units of the concentrator of the Matagami Division of Noranda Inc. have been sampled for particle size distributions, chemical assays, and gold and silver contents in each particle size interval. The data are upgraded by the mass balance package BILMAT. These results, in conjunction with microprobe analyses, are used to quantify the silver losses in the copper cleaning flotation
Publication: CIM Bulletin
Author(s): D. HODOUIN, M. GARON,M. REMILLARD, M. THERIEN
Keywords: Mineral processing, Flotation, Lac Mattagami, Copper, Zinc, BILMAT, Mass balance calculation, Computer applications
Issue: 919
Volume: 81
Year: 1988
Text
Summary: This paper discusses the importance of considering residence time distribution (RTD) in the design of flotation and mixing circuits and in the analysis of operating problems. The experiences and successes of Brunswick Mining in this area are covered and include: the development of a practical RTD measurement technique using pulp conductivity, baffle installation to improve the RTD of existing process equipment, and the method in which RTD considerations have been used to design the newest...
Publication: CIM Bulletin
Author(s): J.E. NESSET
Keywords: Mineral processing, Flotation, Residence time distribution.
Issue: 919
Volume: 81
Year: 1988
Text
Summary: In recent years, computer based "expert systems" have been taking on large complex tasks for which no exact algorithmic solutions are feasible; tasks previously reserved for human experts requiring empirical knowledge, judgment, experience, developing a "best solution" by the use of plausible reasoning. Mining method selection is an appropriate area for the application of an expert system because extensive and detailed knowledge is required to make a "best"...
Publication: CIM Bulletin
Author(s): S. BANDOPADHYAY, P. VENKATASUBRAMANIAN
Keywords: Computer applications, Mining method selection, Expert systems.
Issue: 919
Volume: 81
Year: 1988
Text
Summary: A four-inch compound water cyclone (CWC) was tested to evaluate its gold recovery characteristics when processing -4.8 mm run-or-pit, placer material. Neutron activated placer gold particles (840 to 37 microns) were used as radiotracers (198Au) in a closed circuit CWC test loop to determine concentrator recovery; a procedure believed unique to this study. The effect on gold recovery of gold size and shape, feed pulp density, feed pressure, vortex finder clearance (VFC), CWC cone type,...
Publication: CIM Bulletin
Author(s): DANIEL E. WALSH, P.O. RAO
Keywords: Mineral processing, Compound water cyclone, Gold recovery, Placer gold, Concentrators, Beneficiation, Radiotracer.
Issue: 919
Volume: 81
Year: 1988
Powered by Coveo Enterprise Search