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Membrane technology has been available for over 36 years, but has been used sparingly in the general mining industry. However, recent developments in polymer chemistry, spiral wound element construction, pretreatment equipment and techniques and an expanded understanding of membrane fouling and cleaning techniques have dramatically improved the reliability and robustness of membrane based systems in the mining industry. Harrison Western has expanded the use of this “new” technology to enhance the use of membrane technologies to separate metals from large volume heap leach mining solutions containing copper, zinc, and iron, gold or silver. Moreover, membrane technologies are ideally suited to fractionations that add value to processing fluids from refineries like separating metals from acids or concentrating acids and producing high quality process fluids. Finally, wastewater from Acid Mine Drainage (AMD) or, as in the case of the Newmont Yanacocha Mine in Peru, the treatment of excess barren leach solution created during the rainy season, can be cost effectively processed to meet World Bank Standards for surface discharge. Polymeric membranes, specifically thin-film composites, have been developed that will purify, fractionate or concentrate gold, silver, copper, zinc or nickel. Recent applications have been developed for spiral wound modules that operate across the pH spectrum from 0 to 14. Systems using membranes have been constructed that operate on feed streams from 140° C to 300 centipoise. Opportunities exist to apply membrane technology to concentrate gold, silver, copper, zinc or nickel using thin film composite membranes. Engineered membrane types can operate across the spectrum from low pH (<2) acid applications to high pH > 10 cyanide applications. Incorporating HW EMS™ membrane technologies into current mining operations could allow one to increase production because the membrane technology would be used to pre-concentrate heap leach solutions, and therefore, increase utilization of existing extraction and refinery capabilities.

Jan 1, 2007

By R. Chen

Most tunnels built in Sydney encounter similar ground situations; they penetrate either the Hawkesbury Sandstone or the shales that lie beneath the city. Tunnels in these materials are generally sup-ported by rock bolts in combination with a shotcrete lining. A method of analysis is presented to improve our understanding of the long term behaviour of fiber reinforced shotcrete (FRS) materials and the tunnel support systems. A finite element method SAFEA (Semi-analytical FE Analysis) is developed to model the combined creep behaviour of a shotcrete lining and the Hawkesbury Sandstone. To model the time-dependent creep behaviour, the bulk modulus and shear modulus of the materials are represented by logarithmic functions in time. A Laplace transform is then applied to these functions of time and the solution of the problem found from a finite element analysis. Tablot?s method is then used to invert the transformed values and find the solution in real time. The time dependent creep deflection of the numerical tunnel models reflects the interaction of the shotcrete lining and rock which have different creep parameters.

Jan 1, 2008

By R. L. Guerguerian

Nowadays, most grinding mills driven by a wrap-around ring motor are operating successfully. Some of the earlier problems could be attributed to the lateral stiffness and stability of their bearings. As a result, modifications to the bearings included the rearrangement of the shoes, or the addition of more shoes, closer to the horizontal centerline. This technical paper reports a study of the effects of bearings on the lateral stiffness of grinding mills driven by a wrap-around ring motor. The discussions cover the design of the four shoe trunnion bearings and examine the effects of the angular location of the shoes.

Jan 1, 2000

The Coeur Rochester Mine is one of the largest and lowest cost primary silver mines in the United States. In January, the mine surpassed 3.1 kt (100 million oz) of historic silver production. Rochester is owned and operated by Coeur d’Alene Mines, the world’s largest primary silver producer. Rochester is the world’s seventh largest silver mine. It also produces gold — more than 31.1 t (1 million oz) in historic production. Cash operating costs have averaged 8 cents/g ($2.58/oz) of silver since operations began in 1986.

Jan 1, 2004

By Scott Ellenbecker

The formation in Newmont Mining?s Phoenix Mine near Battle Mountain, NV contains high levels of abrasive quartzite as well as gold, copper and silver. Newmont started mining operations at Phoenix (formerly Battle Mountain Gold) three years ago and the planners knew they were working with a challenging geological formation. But as it turned out, it was more challenging than anticipated. Mine manager Mark Evatz said, ?Anything that touches Phoenix rock wears fast. The rock fights back here.? To contend with the hard conditions, Newmont uses Atlas Copco?s Pit Viper 271 (PV-271) blasthole drill. Because of the hardness of the rock, drilling at Phoenix requires hammer drilling and the mine uses Atlas Copco TD65 hammers with 171 mm (6.75 in.) bits. The mine?s PV-271?s are outfitted with a single 41 m3/min (1450 cfm), 2.4 MPa (350 psi), oil-flooded air compressor. Phoenix has six Atlas Copco PV-271 drill rigs plus an Atlas Copco DML and a DM45 midrange blasthole rig. The mine?s goal is to keep 3.6 Mt (4 million st) of muck in inventory to stay ahead of the shovels and support needed operational flexibility (ore control related). Drilling efficiency has been a continuous point of improvement since operations began at the mine. The single-pass depth capability of 16.5 m (55 ft) on the PV-271 helped with that. Originally, the plans called for 6-m (20-ft) bench heights, supported by 7-m (23-ft) drill depths, and time spent moving from hole to hole was eating up productivity. Drilling on that plan resulted in drilling an average of 14 m/h (47 ft/hour). When depths were changed to 13-m (44-ft) drill depth, supporting blasting of 12-m (40-ft) benches, they were able to use the single pass capacity of the PV-271. Performance increased to more than 18 m/h (60-ft/hour) an hour. Although the drill depth change largely supported the improvement, other aspects of continuous improvement associated with improved knowledge of the Pit Viper drills helped as well.

Jan 1, 2009

By Lei Pan, Venkata Atluri, Xuming Wang, Yuesheng Gao, Jan D. Miller

The wetting characteristics and water film stability at the talc surface have been studied, particularly the effect of polysaccharides such as guar gum, starch, and dextrin. Talc is a gangue mineral in the flotation of base metal sulfide ores, precious metal sulfide ores, and platinum group metal (PGM) sulfide ores. Talc surfaces were investigated using surface analysis techniques including atomic force microscopy, high-speed video bubble attachment measurements, and wetting film stability measurements using a synchronized tri-wavelength reflection interferometry microscope (STRIM). In the presence of polysaccharides, there is a significant increase in bubble attachment time at the talc surface, but only a slight change in contact angle, which suggests that polysaccharide depression of talc is due primarily to the slow rate of bubble attachment and not due to a change in contact angle. The critical rupture thickness (hc) for a hydrophobic talc surface was found to be 56 nm, while the hydrophilic phlogopite surface of similar structure has an equilibrium film thickness (he) of 25 nm. At low polysaccharide concentrations, the wetting films formed on the talc surfaces were unstable, but at high concentrations the wetting films became stable with similar thickness values as the critical rupture thickness, and bubble attachment did not occur. However, it was found that the critical and equilibrium film thickness values do not change significantly with the polysaccharide type or concentration. The results from this research help us understand further details of film rupture and displacement during bubble attachment.

By R. A. Meyr, K. A. Perry

Following three major mining accidents in 2006, the MINER Act of 2006 was enacted by the U.S.Congress. The U.S. Mining Safety and Health Administration subsequently released the Final Rule on Refuge Alternatives for Underground Coal Mines, which required every underground coal mine to install refuge alternatives to help prevent future fatalities of trapped miners in the event of a disaster. The following paper documents the research that was performed on a structural wall to be used in conjunction with a breathable air system to create a refuge alternative. A 103.4-kPa (15-psi) safe haven polycarbonate wall for use in underground coal mines was designed and modeled using finite element modeling in ANSYS Explicit Dynamics. The successful safe haven wall design was modeled for an actual underground coal mine environment using the explicit finite difference formulation program FLAC3D to determine the responses of the wall and surrounding strata within a mine. A full-scale design was fabricated and installed in an underground coal mine to determine any construction constraints and as a final step in proof of concept for the safe haven wall design. This paper is meant to introduce the reader to a new wall concept to be used in conjunction with current technology.

Jan 1, 2013

By G. J. Olson

This paper describes the microbiology basics underlying heap and tank biooxidation of metal sulfide ores and concentrates. The primary organisms are identified and described along with the reactions they catalyze and their growth requirements. Also described is the interaction between ore leaching bacteria and the leaching environment in terms of solution chemistry, temperature, and mineral precipitation. Specific factors and agents that stimulate or inhibit growth and activity of ore bioleaching will be identified. Some of these factors are organism-specific and others are generic for microorganisms that grow under acidic conditions. Current knowledge of the limits of bioleaching in terms of dissolved ions in leach solutions, pH, and temperature will be summarized.

Jan 1, 2003

By G. C. Presley

Estimated domestic production of pumice and pumicite in 2004 increased about 23 percent since 2003, according to the U. S. Geological Survey (USGS). The USGS estimate of domestic production of 687 kt(757,000 st) for 2003 turned out to be 870 kt (959,000 st)of actual production. The USGS estimated the value of pumice and pumicite sold or used in the United States to be $26 million in 2004, up $4 million from the value in 2003. There was an estimated decrease in the mine, or mill, average price to $24.14/t ($21.90/st) in 2004 from $25.19/t ($22.85/st) in2003.

Jan 1, 2005

The latest in mining technology and equipment will be show-cased this month at MINExpo International 2004. The event, billed as the world’s largest mining equipment exhibition, is set for Sept. 27-30at the Las Vegas Convention Center. MINExpo, sponsored by the National Mining Association (NMA), is held every four years in Las Vegas, NV. This year’s event is expected to attract more than 40,000 mining industry professionals and executives from around the world. And several key members of the U.S. Congress and other senior government officials are expected to attend. In addition, senior industry and government officials from Asia, Europe, Australia, Africa and South America will be on hand.

Jan 1, 2004

By J. Kretschmann

Around the world, mining has been done for thousands of years for the benefit of humankind. The winning process in mining operations ends with the depletion of the deposit or its closure if the operation becomes economically unprofitable. After that, a period of post-mining follows which may last for a very long time and which is generally regarded as a period of hazards, risk and high cost. In the USA alone, approximately 500,000 abandoned mines do exist; worldwide, there are millions. In Germany, too, we have had to deal with abandoned mines for a considerable period of time now.

Jan 1, 2012

By B. Burke, R. Colquhoun, K. Thomas, R. Walton, D. Fentie

The new Roasting Facility at Barrick’s Goldstrike Mine in Nevada, U.S.A. was developed to process 12,000 tons per day of refractory gold ore. The process consists of crushing, dry grinding, roasting, extensive gas purification, calcine quenching and leaching in the presence of activated carbon. The new plant is integrated into the existing Goldstrike facility, treating ore from both open pit and underground sources. The process design, procurement, construction and commissioning of the Roaster facility was performed successfully over a 3½ year period with peaks of 400 engineering personnel and 950 construction personnel supporting the project. The US$330,000,000 project was completed ahead of schedule and under budget. The commissioning was well planned and proceeded smoothly through a rapid start-up to achieve all primary goals within three months of the start of processing of ore.

Jan 1, 2001

Accurately estimating load distributions and ground responses around underground openings play a significant role in the safety of the operations in underground mines. Adequately designing pillars and other support measures relies highly on the accurate assessment of the loads that will be carried by them, as well as the load-bearing capacities of the supports. There are various methods that can be used to approximate mining-induced loads in stratified rock masses to be used in pillar design. The empirical methods are based on equations derived from large databases of various case studies. They are implemented in government-approved design tools and are widely used. There are also analytical and numerical techniques used for more detailed analysis of the induced loads. In this study, two different longwall mines with different panel width-to-depth ratios are analyzed using different methods. The empirical method used in the analysis is the square decay stress function that uses the abutment angle concept, implemented in pillar design software developed by the National Institute for Occupational Safety and Health (NIOSH). The first numerical method used in the analysis is a displacement-discontinuity (DD) variation of the boundaryelement method, LaModel, which utilizes the laminated overburden model (Heasley, 1998).

Jan 7, 2020

By R. Rushforth

The surge of activity in the solar energy market, spurred by government incentives, has created new and more efficient solar technologies, but issues surrounding land- and water-use have backlogged the full-scale development of solar farms. This paper explores siting solar power plants on degraded or polluted lands, such as mine tailings impoundments. Historically, mining and has been integral to Arizona?s economy, but has dwindled in relevance due to urban pressures and environmental regulations. Currently, it is legal to site solar power plants on degraded or polluted lands, but the question remains whether the economics of this degraded lands solar development is more favorable than developing pristine land. Therefore, we explore economics of developing mine tailings impoundments at both the institutional and financial level. Methods of research for this paper were interviews with government regulators, environmental advocacy organizations, farmers, and mining company executives. Financial models using extant tax incentives show a positive net present value for the installation of solar power plants, even when accounting for the costs of land remediation.

Jan 1, 2011

By Andy Mille

The paper highlights development of tunneling methodology in the UK during the years 1990-2000 using the example of two major tunneling contracts where there solution of difficult tunneling problems during construction has benefited the industry as a whole. The paper deals with specific difficulties on two Contracts. The London Water Ring Main 80 kms (50 miles) long tunnel average internal diameter 2.54 m (9 ft4 in) and the Brighton Stormwater Tunnel 5.2 km (3.2 miles) long tunnel with an internal diameter of 6 m (19 ft 8 in). The results of human endeavour and technological innovations will demonstrate the giant strides made in tunneling methodology in the last decade of the 20th Century.

Jan 1, 2001

By L. Ozdemir, M. Cigla

This paper presents and discusses some of the computer models developed and currently used at the Earth Mechanics Institute (EMI) of the Colorado School of Mines (CSM). These include the performance models for full and partial face machines. Examples of input and output of these models will be illustrated for typical mining operations by using machines such as Tunnel Boring Machines (TBM), Continuous Miners (CM), Marietta borer miners and longwall drum shearers. The general approach to modeling and the available models are discussed and some examples of these models are presented. The comparison between the estimated and achieved performance, as well as the degree of improvement in the performance due to balancing and modification in cutterhead design are also discussed.

Jan 1, 2000

By Mutombo Nombe, Avimanyu Das, Rick Honaker

Enhanced gravity separators (EGS) provide a more efficient separation than froth flotation when cleaning coal in the 150 x 25 µm particle size range. To improve the performance of an EGS unit, air bubbles were injected into the feed stream in an attempt to decrease the apparent density of the coal particles due to the formation of bubble-coal particle agglomerates. Air injection had a significant impact on operating characteristics and separation performance. Coal recovery was increased by 10 to 20 absolute percentage points while a 2 percentage point drop in the minimum product ash content was also achieved.

Jan 1, 2005

By Rolando Gonzalez

Mexico’s role in the world economic community continues to grow. And it is important that the country makes use of its natural wealth, including its large underground deposits of minerals and metals. With that in mind, Industrias Peñoles S.A. de C.V.(Peñoles), a mining, smelting and refining company, began mining lead, zinc and other metals from the Francisco I. Madero Project (FIM). The mine is located about 600 km (370 miles) northwest of Mexico City in the state of Zacatecas. Peñoles plans to remove about 3 Mt/a (3.3 million stpy) of ore from FIM. To achieve this goal, the company needs to optimize its processing, to maximize the amount of metal it extracts through FIM’s large flotation lead-zinc concentrator. To ensure high productivity, Peñoles and its contract engineering firm, M3 Engineering and Technology, of Tucson, AZ, have implemented anore processing system.

Jan 1, 2003

By S. K. Gilman

Zircon (ZrSiO4) sand production of about 1.1 Mt/a(1.2 million stpy) predominates the global supply of zirconium minerals. Baddeleyite (ZrO2) contributes less than 1 percent of supply. Zircon is almost exclusively produced as a co-product from the mining of titanium minerals, mainly from mineralized beach sands. In 2004, there were a number of new projects under consideration that were more dependent on zircon revenue than for titanium minerals. This reflected sustained higher zircon prices and forecast ongoing supply shortages in the absence of major new discoveries.

Jan 1, 2005

By Jon A. Hummer, MICHAEL R. SHAHAN, Aleksandar D. Bugarski, Shawn Vanderslice

Occupational exposures to respirable dust and submicrometer aerosols emitted by diesel-powered equipment are a health concern for underground mining operators and regulators. A study was conducted in an underground mine with the objective to identify, characterize and source apportion airborne aerosols at the setup face and recovery room during longwall move operations.