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By Rex L. Outzen

Houston International Minerals Borealis Project is an open pit heap leach operation. The operation uses open pit mining, two stage crushing, agglomeration, heap leaching, zinc precipitation and induction refining to produce approximately 50,000 ounces of gold per year. Due to the ore being extremely ameanable to heap leach processing techniques, low manpower requirements and efficient management, the operation is one of the lowest cost gold producing operations in the United States.

Jan 1, 1984

By Clive Wilson, Bruce Hutchison, Daniel N. Adams

Two three-lane highway tunnels, 700 and 2900 m long, make up the driven tunnels portion of Melbourne City Link. Tunnel construction, using design-construct delivery, commenced in May 1996. Construction required excavation through varying rock conditions; temporary support included ground freezing, pipe-spiling, steel sets, and rock bolts. Permanent support for the tunnels required both drained and undrained tunnel cross sections using unreinforced concrete. This paper reviews the construction methods, and highlights some of the not-so-standard designs developed while construction was underway.

Jan 1, 1999

By F. N. Kissell, N. I. Jayaraman

Dust scrubbers on continuous miners are steadily gaining in popularity. Recent US Bureau of Mines research on scrubbers is reviewed, with emphasis on development of a new type of water-powered scrubber that can be retrofitted to existing miners; comparison of scrubber effectiveness with blowing and exhaust line ventilation; and improving the quartz dust collection of flooded-bed panels.

Jan 1, 1991

By A. Chattopadhyay, J. Res

High-level electrical energy can be suitably converted to shock waves of stress that, in turn, may be used for disintegrating hard rocks. This development, known as the electrohydrodynamic method, is very safe and highly economical compared to other methods of rock breaking. This paper deals mainly with development of the equipment and some details of the experimental work carried out with different rocks and concrete block.

Jan 1, 1988

By D. A. Harman

The U.S. Environmental Protection Agency recently recognized Newmont and other mining companies, along with the Nevada Division of Environmental Protection for their voluntary work in reducing mercury air emissions. One example of this voluntary effort is the installation of a reactive scrubber to capture mercury vapor from the exhaust of a carbon regeneration kiln at Newmont’s Twin Creeks Mine. After considering the available technologies, a proprietary reactive scrubber, developed by ADA Technologies, Inc., was selected and is currently being commissioned. Mercury removal rates greater than 90% have been documented.

Jan 1, 2004

By A. Shah, L. W. Saperstein, M. C. Radomsky, D. L. Passmore

The development of microcomputer software that provides an analysis of pit-specific accident and production data for the mining industry is seen as a vital component in a total loss-control system. The Mine Injury Reporting System (MIRS) allows users to access accident and production data prepared by the Health and Safety Technology Center of the Mine Safety and Health Administration of the US Department of Labor for any particular state and to generate a simple, yet informative, report.

Jan 1, 1990

By J. A. Slattery, C. E. T. White

Although trace amounts of Indium are found in many ores, commercial production of the metal has come almost exclusively from residues, flue dusts and slags generated by Zinc recovery operations. Our paper attempts to summarize the various approaches used to recover Indium from these by-products. Some comments on production and price trends are Included as well as our views on future availability.

Jan 1, 1983

After a discussion of the principles of heavy-mineral enrichment and the sedimentary history of shelf sediments, four models are described that can explain the genesis of heavy-mineral deposits in shelf areas. On the basis of these models, the heavy-mineral potential of most shelf areas is estimated to he significantly lower than the potential of their neighboring coastal plains.

Jan 1, 1991

By Trevor J. Smith, Kevork A. Chouzadjian, Rob S. Burns, Steve J. Roden, Michelle A. Spieth

Investigations were undertaken to improve the recovery of silver from CRA's Hidden Valley gold/silver deposit by the addition of calcium peroxide. The addition of 0.75 to 1.5 kg/mt of calcium peroxide improved silver extraction by 5 - 300 and reduced cyanide consumption by up to 30%. Gold extraction was also marginally improved in some of the tests. The results are of economic interest and plant trials will be initiated once operations are underway.

Jan 1, 1990

By Leopoldo Cortez, Fernando Durão

The dynamic control of a froth flotation section is simulated through a neural network feedback controller, trained in order to stabilize the concentrate metal grade and recovery by applying random step changes to the feed metal grade. The results of the application example show that this controller seems to be sufficiently robust and a good alternative to handle a non-linear process.

Jan 1, 1995

By D. John Curtis, Gordon S. Crighton, John C. Hester

The six main drives needed to build 55 miles of 4.8 and 7.7 metre i.d. tunnels in 33 months called for careful co-ordination of the design of tunnel boring machines and linings. The implications of these requirements are discussed, with particular reference to the selection of tunnel liners. The solutions adopted are detailed and details are given of the specifications and procedures adopted. The design methods employed for liners are outlined. The construction methods are described and current performance figures given.

Jan 1, 1991

By Howard R. Postovit, Bonnie C. Postovit

Raptors are birds of prey. In recent years, these birds have become highly regarded and have been given protection under various state and federal statutes. Surface coal mining can have both negative and positive impacts on raptors. Mitigation strategies and enhancement techniques can be implemented to alleviate negative impacts. The success of habitat reclamation will determine the long-range impact of mining on raptors.

Jan 1, 1989

By John D. Welsh

Heap leach pad liners are important to leach operations for maximizing recovery of gold bearing solutions and minimizing potential environmental impacts. Liners must be designed so that they can be built economically, but careful attention must be paid to the potential for liner damage during installation or placement of ore on the completed pads. This paper summarizes field experience gained on several leach pad construction projects in Nevada. Both soil and synthetic membrane installations are discussed. Emphasis is placed on principles that should be considered during design to provide economical and practical leach pads.

Jan 1, 1987

By M. Gaft, G. Panczer

Sedimentary francolite and magmatic apatite are characterized by specific laser-induced time- resolved luminescence, which allows phosphate to be distinguished from accompanying dolomite. The "selective window" parameters are: he, = 337 nm, delay time after laser pulse is 0.5-5 ps, and detection spectral range is 400-525 nm. In the case of nonuniform distribution of phosphate minerals, it makes it possible to accomplish lasero- luminescent sorting and to receive intermediate product with a lowered dolomite contents.

Jan 1, 1999

By T. Mudder, K. Harvey

The objectives for closure of a hard rock mine include minimizing long term environmental liability, attaining regulatory compliance, and maintaining geotechnical stability, while closing as cost-effectively as possible. Proper planning for closure should come during the feasibility study, design and permitting phases, and during operations as updates. The lack of a proper or updated closure plan can result in severe environmental and economic consequences. Effective mine closure is the result of a combination of innovative concepts, long-term commitments, and multi-party cooperation. The purpose of this paper is to discuss concepts, commitments, and cooperation as they relate to an effective closure plan.

Jan 1, 1999

By Ulf Svensson, Donald E. Zipperian

This paper reviews commercial installations of FLOTAIRE Column Flotation Machines for metallic, nonmetallic, and coal flotation. Second generation FLOTAIRE Column Flotation Machines employ dual aeration systems to provide a mixture of air bubble sizes. Operating data presented in this paper shows that optimum grade and recovery relationship for each rougher, cleaner, and scavenger application are obtained by adjusting the ratio and volume of aspirator air bubbles and micro diffuser air bubbles.

Jan 1, 1988

By V. P. Keran, K. Leung

Two 32 foot x 14% foot, 6.4 MW autogenous mills have been installed in the Mount Isa Mines Copper Concentrator to replace the fine crushing plant, fine ore bin, rod mills and primary ball mills. This paper describes the reasons for the change, the rationale for the new circuit design and configuration, the design and scale-up processes used to size the mills, considerations for the installation of large mills inside an operating concentrator and some early operating data.

Jan 1, 1992

By K. D. Allen, M. J. Blattman

The problem of measuring the amount of rock removed during a given time interval is faced by most mining operations. Many methods have been developed with varying degrees of success, dependent upon the mining method and the availability of usable data. The Rosebud Mine has been in production for nearly two years, employing several techniques to estimate monthly production from underground production stopes. The use of three-dimensional solids generated from survey data has greatly improved the reliability and confidence of monthly production reports. The authors will summarize the methodology currently being utilized at Rosebud.

Jan 1, 1999

By N. B. Greninger, M. J. Sapko

The US Bureau of Mines conducted, through joint funding with the Colorado Mining Association, large scale oil shale rubble fire tests to investigate flammability characteristics and different methods of extinguishment. Ignition of large rubble piles was easily accomplished. Foam blankets could be used to control surface flames. The results of these large scale tests confirmed that water was effective but not particularly efficient in extinguishing deep seated oil shale fires. It took up to 1.7 times as much water to extinguish afire as anticipated on the basis of a simple cooling model, assuming 100% utiliza-

Jan 1, 1991

By R. L. Grayson, J. R. Warneke

Environmental conflict between the public and private sectors, including mining, is highly visible and often based on deeply divergent environmental, social, and economic values. In order to achieve sound public policies by government, scientifically rigorous and objective analyses of mining’s impacts are demanded. Material flows accounting and analysis, linked with other data to generate indicators of environmental, social, and economic impacts of mining activity are means toward providing cogent input into public policy-making on key issues. This paper will present a material flows analysis scheme for the coal industry and recommend derived, objective indicators of coal mining’s impact on society.

Jan 1, 2004