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By S. G. McDowell

Automation techniques are used during the design stage of continuous miners to decrease the time required and ensure the accuracy of the design. This is followed by automated manufacturing processes to reduce manufacturing time and improve the quality and consistency of parts. Combined, the result is a more reliable machine that can provide ongoing production capability. With the use of automation to enhance operator effectiveness and monitor machine condition, the productivity of machines is also improved. Productivity of continuous miners doubled over a 10-year span (Fig. 1). Although this article focuses on the continuous miner, it should be recognized that production increases of the continuous miner would not be realized without increased capabilities throughout the rest of the mining system. There are several aspects of automation that have played a role in providing increased continuous miner productivity. Though some are considered indirect, they still had significant influence on the overall result. Basically, productivity increases are obtained by cutting, loading and transporting the coal at a maximum rate. In addition, these tasks must be consistent, with minimal downtime. Therefore, the miner had to improve in operational capability and reliability. Automation techniques used during machine design, manufacturing and operation have all played significant roles in achieving higher productivity.

Jan 1, 1991

"The National Mining Hall of Fame and Museum (NMHFM) announced the class of 2019 National Mining Hall of Fame inductees. This year’s inductees, selected by the National Mining Hall of Fame’s Board of Governors, represent exceptional financial acumen in assembling several operations that formed the basis of a successful American mining company; conception and development of equipment which contributed to improved efficiency and mine safety; and unrelenting advocacy for the U.S. mining industry and its workers. These individuals, selected for being determined, forward-thinking innovators, doers and leaders have propelled the industry toward vastly improved safety and social responsibility.The Prazen Living Legend of Mining Award, named for renowned mining artist Gary Prazen, will also be presented at the ceremony. This award recognizes an individual or organization for significant and sustained commitment to educating the public about the relationship of mining to our everyday lives through educational materials, programming, and outreach.2019 National Mining Hall of Fame inducteesFrank Calandra, Jr. has devoted more than 50 years to the mining industry and he is an icon in ground control technology for the mining, tunneling and civil construction industries.From the ground up, his passion, sweat equity and shrewd business acumen have grown Frank Calandra, Inc. (FCI) and Jennmar from a single plant in Pennsylvania to a world-class enterprise with 25 plants employing thousands globally. As evidenced by Calandra’s more than 20 patents on ground control devices (not to mention the additional 80 patents his companies hold), his innovation and commitment to safety have made underground mining safer and more efficient. In the late 1970s and early 1980s, Calandra was instrumental in upgrading American Society for Testing and Materials (ASTM) standards in roof control for both state and federal regulations. Through his work with industry associations such as the National Mining Association, National Coal Council and Center for Energy and Economic Development, among others, Calandra has contributed his time, expertise and financial support to ensure a balanced political and regulatory climate for mining. Calandra is an inductee of the West Virginia Coal Hall of Fame."

Aug 1, 2019

By John Dean

"Pumping backfilling medium used to fill in holes and caverns in mines is challenging. The often viscous, high solids materials are extremely abrasive and can destroy pumping systems in a matter of days. While a number of options are available, using a progressing cavity pump can often be the best solution. High pressure and capacity capabilities, coupled with low wear rates, ensures reliable cost effective operation.Thickened slurry backfilling for underground/excavation mining applicationsVoids and caverns develop as a result of mining operations penetrating deep into the earth seeking natural resources. After extracting all the ore from a mine, operators need to fill in these voids to preserve the integrity of the mine structure. They do this by pumping in a backfill medium. Each mine uses a different mix of components for backfilling, depending upon the mine’s specific structural requirements and environmental concerns, particularly water requirements. Most backfill mixes contain cement, or another cement-like substance, that acts as a binder to hold the backfill medium together. This is combined with tailings (unused rocks and waste from processing and/or extraction), and may also include chemicals or other binders to increase the material’s strength.Backfill pumping challengesPumping the backfilling medium can be a significant undertaking. This process involves transporting very viscous and high solid materials; the mix may contain 60-80 percent solids. These backfill slurries are extremely abrasive and the viscous material can wreak havoc with pumping systems. The material’s paste-like consistency presents problems for standard centrifugal pumps often used in other mining applications.Added complexity is posed when trying to achieve the required pressure, which depends upon how far away the material has to be pumped. It is not difficult to meet the pressure requirements if mixing the backfill material close to the area to be filled. However, pumping from extreme distances can be problematic — a great deal of pressure is required to transport the material from the mixing area to a distant backfilling site. Ideally, operators should be as close as possible to where they are filling, so they can use a smaller pump with lower power requirements."

Dec 1, 2018

What is your assessment of the status of the mining industry as we see some evidence of an economic recovery? I am optimistic about the short and midterm prospects for the industry and, hence, for the professionals in the industry that constitute the majority of the SME membership. All who will read this interview recognize that the quality of life we enjoy today is largely a result of our achievements in the mining and minerals processing sectors. I believe that the sustainability of that quality of life and the aspirations of other sectors of the global community to attain that same lifestyle will significantly depend on the continued successes of these industries. Looking at some of the traditional economic indicators, we see predictions of continued increases in gold prices during the next 12 months as a new round of quantitative easing keeps real interest rates low and drives excess capital flows from countries with trade surpluses - who have traditionally parked their money in U.S. government bonds - into other investable assets, such as gold. On the fuel side of the industry, we have during the last decade seen a steady rise in the cost of coal, and some of the recent spot prices have seen dramatic increases. Some suggest that coal prices may rise sooner than anyone expects, as global reserves are revised downward. This is based on the hypothesis that some of the main coal-producing countries are overestimating supplies and that coal prices could start rising far sooner than anyone thinks - with obvious serious implications for energy policy. Those forecasters note that, for the past couple of decades, global supply has been dropping at a faster rate than consumption.

Jan 1, 2011

By C. A. Fleming, C. J. Ferron, I. Dymov

An oxidized gold/silver ore from Mexico has been evaluated at Lakefield Research in order to develop an economically viable treatment flowsheet for the recovery of gold and silver. Initial cyanidation test results indicated that at least 20 kg/t cyanide was required for maximum gold and silver extractions, due to high cyanide consumption by an oxidized zinc mineral present in the ore. A process was developed for the recovery and recirculation of the cyanide from the leach liquors. The proposed flowsheet included direct cyanidation, CCD and Merrill-Crowe, followed by precipitation of the zinc associated with cyanide with sodium sulphide and recycling of the regenerated cyanide liquor to the leach circuit. The process was demonstrated during a continuous pilot plant. A mill has been erected recently in Mexico and has been operating using this flowsheet.

Jan 1, 1997

By Leslie M. Burnside, Gene E. McClelland, Roy R. Cellan

Revegetation of neutralized heap leach material in the arid environment of the Great Basin represents a challenge of avail­able technology. The chemical and physical environment of spent and neutralized ore is inhospitable for germination and establishment of desirable long term vegetation. Common soil amendments were tested to dete1mine if the heap material could be made more conducive to plant growth. Decommissioned heap material profile samples were collected and reconstructed in columns at bench scale. The column profiles were amended and subjected to three leaching regimes, and representative meteoric conditions. The soil amendments provided positive results for ameliorating the heap material limitations and providing a medi­um conducive to plant growth. The bench scale study also pro­vided insight for the future of heap leach planning and design with successful reclamation in mind at the forefront.

Jan 1, 1998

"With a longstanding reputation for engineering expertise, Weir Minerals continually develops solutions and technology to better serve the mining industry. Recognizing that throatbush wear rate has a major impact on the overall efficiency of slurry pumps, Weir Minerals has developed superior rotating and axial adjustment technology.In many applications, the pump’s throatbush is the component that has the shortest life compared to the impeller and liners, with considerable variability.Adjusting the gap between the throatbush and the impeller front shroud reduces hydraulic recirculation in the pump. This prevents localized wear on the throatbush, improves hydraulic efficiency and lowers the total ownership cost for the operator. To avoid impacting the plant’s production, these adjustments are often performed while the pump is operating. However, this can have safety implications for individuals working at the front of the pump unit.“Manually adjusting an alloy throatbush on a large pump requires several people and is laborintensive. It requires mechanical tools to adjust the four pusher bolts, one at a time, in order to reduce the gap between the throatbush and impeller. We wanted to find a safer and quicker way to extend the wear life of the pump with regular adjustments, which led us to development of this technology,” said Marcus Lane, global product manager for centrifugal pumps for Weir Minerals.“Our automated throatbush adjustment solutions are available for pumps fitted with either rubber or alloy throatbushes on Warman slurry pumps used in the most arduous applications, and have been designed with our customers’ safety and pump operation in mind. By mechanizing the adjustment procedure, personnel are removed from the line of fire, and the accuracy of axial movement is increased,” said Ron Bourgeois, director of slurry pumping technology group for Weir Minerals."

Mar 1, 2019

By Earl Parker

The mining/mineral processing industry constantly faces the challenges of handling tons of material in a variety of processes such as crushing, milling, drying, belt transfer and loadout. These processes result in the production of high volumes of dust. A variety of dust detection and collection equipment is needed to properly manage these emissions to remain compliant with stringent air quality and safety requirements. Dust monitoring and bag leak detection can provide ways to reduce air pollutants, make work environments safer and remain compliant with requirements from the U.S. Environmental Protection Agency (EPA), U.S. Mine Safety and Health Administration (MSHA) and U.S. Occupational Safety and Health Administration (OSHA). There are several approaches to monitoring particulate emissions from dust collection equipment. These can include visual inspections, differential pressure gauges or bag leak detection systems. Bag leak detection and monitoring systems can be optical, light based or electrostatic/triboelectric. Recent developments have advanced the efficiency and reliability of electrostatic/triboelectric style monitors. New technological improvements have been developed that are based upon the principal of unifying dc (impaction) and ac (induction) signals and incorporating other proprietary circuit innovations. This higher signal resolution technology results in a more robust and stable measurement for detecting the presence of particulate in a dust collector emission duct or a flow process pipe.

By Norbert Patzelt, Johann Knecht, Wolfgang Baum

The principle of high-pressure interparticulate comminution has been used very successfully since the mid 1980's for grinding a wide range of different materials. A number of reports about operating experience have already been published. High-pressure grinding rolls (HPGRs) are currently making their debut in the mining industry. Experience is being gained with test machines, particularly for the comminution of hard rock. In the grinding of diamond-bearing ore, (Fig 1) interparticulate comminution has already become the standard for liberating the diamonds from the matrix. The advantages of interparticulate comminution are also recognized for the grinding of concentrates (chrome ore, iron ore). Numerous HPGRs are being used very successfully in this field. A testing plant for first-time industrial grinding of coarse, very hard and highly abrasive copper ore was built at Cyprus Amax's plant in Sieretta, Arizona (Fig. 2). The operating experience gained here showed that the grinding of very hard ores places particularly high mechanical demands on the mill. While the machine itself meets the high availability requirements, the wear-protection system proves to be the most sensitive point. Naturally, the properties of the ore to be ground exert a considerable influence on the lifetime of the grinding rolls. This paper describes the wear mechanisms and the wear­protection systems designed to combat these.

Jan 1, 1997

By Wade N. Ellett, K. Marc Le Vier, Timothy A. Fitzpatrick, Kenneth A. Brunk

As the gold mining industry matured through the 1980' s, and into the 1990's, the development of refractory gold orebodies has become more prevalent. Newmont Mining Corporation developed and commercialized flash chlorination for the treatment of carbonaceous preg robbing ores; Homestake Mining Company developed and commercialized the industry's first application of autoclaves. Barrick installed the world's largest autoclaves on whole ore treatment a few years later. Dry grinding and roasting followed at Placer Dome's Cortez, Freeport -Independence and Newmont's Carlin operations. Today, numerous papers are presented on research efforts worldwide which address treatment of refractory gold ores by bioxidation, roasting, autoclaving, alternative lixiviant treat­ment and other novel process ideas. The overall objectives are to develop economic processes for difficult refractory ores where no process exists or conventional practice is cost prohibitive. Successful research can lead to lower operating costs, increased profits, and increased ore reserves. One such research effort directed by E I DuPont de Nemours and Company, Advanced Mining Technologies, was focused on gold ores which were refractory in nature due to the cyanide soluble copper content. Approximately five years of research effort culminated in a patented process (U.S. Patent 5,411,575)1 and the formation of a new joint venture company, AuGMENT Technologies, in 1995 with Newmont Mining Corporation. Today significant progress has been made in moving the laboratory scale tests to commercialization.

Jan 1, 1997

By David Martin Menne

In a small tank, slurry is passed through the high shear impeller zone with small time intervals, and a large proportion is regularly exposed to air at the surface, and at relatively high shear rates. This accounts for significant differences in the performance of large and small tanks. It is preferable to derive data where possible directly from an operating plant rather than applying data generated in small tanks where allowances must be estimated for the above differences [and where slurry aging and often substantial cooling compared to hot freshly milled ore further distorts results]. Various measurements have shown that many gold slurries can suffer extreme variability, as streamers of bypassing material or boules of hold-up periodically condstitute the instantaneous discharge from a tank - the relatively high Yield stress of slurries [around 1 to 10 Pa] causes very incomplete homogenization of slurry in any tank, the worse the larger the tank and the more viscous the slurry. To provide a background for this subject, this monograph presents leach and adsorption models based on the fundamental physics and chemistry of these processes, and includes quantitative discussions of factors which can lead to deviations on scale-up. The Throughflow model which avoids the need for such alowances is then presented, as well as a Computer Programme applying this model, and which allows direct calculation of the effects of:

Jan 1, 1995

For the past two years, Cliffs Natural Resources in Minnesota has tried an experiment: it has staffed a booth at the Iron Range Earth Fest. ?It was a little unusual for a mining company to participate in an event that centers around preserving the Earth?s resources,? said Julie Lucas, environmental manager at Hibbing Taconite Company. ?But Cliffs is a sustainable company and we want to take every opportunity to share information about our practices. We found the response to be overwhelmingly positive.? Cliffs? outreach effort is just one of the surprising ways mining companies across Minnesota are reaching out to stakeholders and finding success. The 85th annual SME Minnesota Section Meeting (73rd Annual University of Minnesota Mining Symposium), held April 17-18 in Duluth, MN, demonstrated the Minnesota mining community?s commitment to connection and collaboration, and how that approach is bringing success.

Jan 1, 2012

By A. Russell, M. N. Hughes, Jack Barrett

The bacterial oxidation of arsenopyrite has been shown to be an efficient, economic and environmentally acceptable method for the liberation of any gold content . The mechanism of the process is not certain but is usually considered to involve direct and indirect reactions with respect to bacterial involvement. The direct reactions are those in which the bacteria attached to the mineral surface cause its dissolution, with dioxygen being the oxidant. The iron(III) produced in solution is the chemical oxidant in the so-called indirect reactions. Barrett et al 2 showed that a synthetic bio-oxidation solution (with no cells present) could dissolve up to 15% of an arsenopyrite sample, the products of the chemical oxidation being iron(II) and arsenic(III). This paper describes an extension of the investigation of the chemical process and its imp! ication for the mechanism of the bio-oxidation of arsenopyrite.

Jan 1, 1990

By Gary Beerkircher

WaterFlush Technology and WaterFlush crushing offers significant operational ben­efits in gold milling operations. WaterFlush crushing is the technology that Nordberg Inc. has developed, tested and proven in an actual operation during the 1980's. Patents have been obtained for both the process and the apparatus of implementa­tion. WaterFlush involves volumetric process controlled water flow into the ore feed cav­ity of a WF cone crusher. While the addition of water in itself is not new, the con­trolled amount of water coupled with the WF crusher operating parameters are revolution­ary. The WF crusher is a specially designed version of Nordberg's Omnicone crusher oper­ating at higher speeds, with a reduced ec­centric throw and higher horsepower capabil­ity. The results are increased capacity, higher crushing energy input and a finer crusher product. The WF crusher product is a slurry containing 40-60% solids by weight.

Jan 1, 1990

By Paul F. Ziemkiewicz, John J. Renton, Thomas Rymer

Any viable model or deterministic formula used to make predictions must follow certain criteria. The standard models and procedures used to project acid load from mining activities operate from a number of assumptions, some of which, although logical, are scientifically oversimplified and, hence, invalid. Highly variable field parameters have lead to highly variable acid projections. Kinetic tests are in themselves misnomers in that no parameters associated with chemical reaction kinetics are ever determined. Sampling error coupled with assumptions made as to the distribution mode of pyritic materials in rock units can lead to highly inaccurate conclusions explaining why acid generation often occurs where none is predicted. The fact that probability theory and paradigms governing luck and chance have not been incorporated into the science of acid prediction undermines any credence placed on such projections. To date, with few exceptions, the acid prediction is logically closer to a game of chance than practical science.

Jan 1, 1991

By F. W. DeVries, J. Brent Hiskey

The search for noncyanide lixiviants for treating gold and silver ores and concentrates is not a new endeavor. However, in recent years, the overall activity to seek a less environmentally controversial reagent than cyanide has occasioned considerable developmental work. While the elegant economy and simplicity of cyanide, because of its selectivity and the ease of recovering gold and silver from the cyanide complexes, is well recognized, two failings have justified the search for alternates: increasing concerns and costs to assure avoidance of environmental damage from cyaniferous liquids and solids, and the need to simplify recovery of gold and silver from refractory ores. Generally, process development work to date on the alternate reagents has lacl<::ed environmental focus ( Hiskey and Devries, 1992). This paper covers briefly the chemistry of various alternates to cyanide and reviews their environmental implications. In each case, environmental overtones are reviewed following the chemistry. For ease of follow-up, the authors have listed sources of information in detail. Alternates examined include:

Jan 1, 1992

By J. A. Meech, C. A. Harris

Expert Systems are being used in the Mineral Industry with ever­increasing frequency. A major advantage of these systems over conventional computer programs is that the knowledge and intelligence of human experts can be captured directly onto a computer for transfer to novices or other lesser experts. These programs allow rapid construction of process models that are not well-understood in fundamental terms, but for which good operational reasoning exists. In addition, user-friendly access to "high-tech" knowledge can be provided to unsophisticated personnel who otherwise might be turned off by unintelligible jargon. As such, these systems can be important training tools for new operators. This paper describes the features of Expert Systems that relate to gold processing plants. Applications include grinding circuit control, supervisory control of reagent addition and pulp density, monitoring and control of CIP/CIL carbon inventories and the operation of carbon stripping and regeneration facilities. A consultative Expert System is described that provides advice on laboratory cyanidation testwork

Jan 1, 1992

By S. Vukcevic, R. Winby, P. C. Miller

There is considerable interest in the bioleaching of chalcopyrite concentrate for the production of copper. The residue of bioleached chalcopyrite often contains gold that needs to be recovered. Despite the high efficiency of copper bioleaching, the residue may contain appreciable quantities of copper, and the difficulties of cyanidation of gold from copper bearing materials are well recognised. This paper reports the results of using different methods to recover the gold values from bioleached chalcopyrite concentrate. In particular, the behaviour of cyanide and cyanide in the presence of ammonium ions as gold lixiviants were studied. The ammonia was employed to reduce the impact of the copper on cyanide consumption. Thiosulphate as a gold lixiviant was also employed with the aim of achieveing rapid leaching rates and to reduce the impact of residual sulphur species on lixiviant consumption. Bromine solution was used to research acidic gold leaching. The paper describes the advantages and disadvantages of using different reagents with respect to reagent consumption, selectivity and kinetic efficiency.

Jan 1, 1997

By David Martin Menne, Chris Campbell-Hicks

Optimisation of many oxide gold processing facilities, in most cases, either does not really take place or if it does take place it happens too late or takes too long. This is unf01tunate as extra profits and early cash flows are lost, in new projects, and/or may not be realised at all in others. The situation is easily avoid­ed by ensuring that the plant optimisation happens immediately following commissioning or for an established operation simply 'biting the bullet' and making it happen immediately as a 'better late than never' decision. This type of optimisation requires intense undiluted focus on each and every problem or restriction that contributes to reduced plant performance or bottlenecks, without letting go, until the predetermined outcome is produced. Thus a dedicated person with specific quantative goals is required for these tasks. Methodology and strategies for optimi­sation are discussed and numerous examples presented. The secret of successful heap leaching is discussed.

Jan 1, 1998

By M. J. Virnig, J. M. W. Mackenzie, M. W. Johns

The properties of Henkel's Aurix® resin which uses a guanidine functionality to recover gold by ion exchange have been described in publications of the International Mineral Processing Congress and Randol International (1)(2). The purpose of this paper is to provide an update on the results of further testwork using Aurix®. Specifically, this paper presents the first results of resin in pulp testing, all the results previously reported were for testwork carried out using synthetic gold leach solutions.

Jan 1, 1995