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By Devin Burns, Saima Ghazal, Michael Owusu-Tweneboah, Kwame Awuah-Offei

Trust in AI systems and the nature and amount of information about the system can influence decision-making. It is, therefore, crucial to understand how AI-powered monitoring systems (e.g., gas monitoring systems) influence miners’ trust and decision-making in emergency evacuation. This work focused on measuring the differences between how participants respond to a simulated underground mine emergency evacuation situation when warnings are represented as coming from a human or AI-based monitoring system. We also manipulated the amount of information participants received about the system, yielding a 2×2 between-participants survey design. The participants received an alert message about rising gas levels in a mine and provided a response on how they would react and reported their perceived safety. We also asked questions to assess their trust in, preference for AI over human-based gas monitoring systems, and whether they are willing to delegate the duties of underground gas monitoring to AI systems. The experiment results show the amount of information had a significant influence on miners’ trust and decision-making. The safety perception of participants based on age, number of children and ethnicity was significantly different from one category to another. This work provides valuable insights as the mining industry deploys AI systems to aid mine safety.

Feb 1, 2025

By Scott Rosenthal, Dave Gilkey, Theresa Stack, Daniel Autenrieth, Ciara Kremer

Jackleg drill operators are exposed to harmful levels of hand-arm vibration (HAV). Anti-vibration handles and gloves provide modest reductions in HAV exposures and forearm muscle exertion from the use of anti-vibration handles and gloves by jackleg drill operators. The goal of this pilot study was to investigate changes in HAV with the use of anti-vibration gloves and handles compared to forearm muscle exertion experienced by operators and measured with surface electromyography (EMG). Five subjects operated the drill under four different cases: no anti-vibration controls, anti-vibration gloves only, anti-vibration handle only, and simultaneous anti-vibration handle and glove use. Muscle exertion was expressed as a percent of maximum voluntary contraction (%MVC) and was compared using Welch’s ANOVA with Games-Howell post hoc comparisons. The case with both anti-vibration controls in use simultaneously (largest grip diameter) was associated with a mean %MVC of 36.13% during operation for all forearm muscles combined, which was significantly higher than that of the other cases (p < 0.05). There were no statistically significant differences in mean HAV exposures. The anti-vibration handle with anti-vibration glove case only increased the maximum allowable exposure time by 8 min as compared to the control case without any anti-vibration controls. These results suggest that the modest HAV exposure reductions from the use of anti-vibration handles and gloves may pale in comparison to the increased muscle exertion resulting from their use, and this trade-off among jackleg drill operators is a potential concern that warrants further investigation.

Jul 12, 2021

By R. Benito

This paper describes the development of a life-of-mine schedule (LOM) for one of the world&apos;s largest known sedimentary copper-cobalt districts located in the Katanga Province, Democratic Republic of Congo (DRC). A particular feature of the Tenke Fungurume LOM schedule is the considerable number of pits/phases for scheduling, each competing to provide the best ore available to a capacity-constrained process facility. This paper discusses the LOM scheduling objectives and constraints, data preprocessing steps such as ore binning, block aggregation and clustering analysis as a scheduling aid, the mine scheduling approach and results and conclusions. Mining Engineering, 2011, Vol. 63, No. 8, pp. 39-47. Official publication of the Society for Mining, Metallurgy and Exploration, Inc.

Jan 1, 2011

By Tyler Luxner

Stillwater Mining Co. (SMC) is the largest primary producer of platinum and palladium in North America. SMC operates two underground mines in south central Montana, along the 45-km (28-mile) platinum/palladium J-M Reef in the Stillwater Complex. The Stillwater Mine exploits 9.6 km (6 miles) of deposit strike length and East Boulder Mine exploits 4 km (2.5 miles) of deposit length. The two mines are 20.4 km (12.7 miles) apart with SMC controlling a considerable length along the entire J-M Reef trace. Production at the Stillwater Mine began in 1986 and in 1988 the first tunnel boring machine (TBM) was commissioned, becoming an integral part of mine development at SMC. TBMs have been used for developing production footwall laterals (FWL) to access new mining blocks at the Stillwater Mine, as well as boring twin crosscut ac-cess tunnels at the East Boulder. Two TBM development expansion projects are currently in progress: the Graham Creek project at the East Boulder Mine, which will extend footwall lateral development 2,591 m (8,500 ft) to the west, and the Blitz project, where a TBM will be commissioned to extend east out of the Stillwater Mine to 3,658 m (12,000 ft) beyond the current production mining front. General strike and dip of the Reef is west to east and to the north, respectively.

Jan 1, 2012

By D. R. McConnell

The seafloor in the US Pacific OCS and EEZ is enriched to varying degrees in critical and economically important minerals such as nickel, manganese, cobalt, copper, zinc, REY (rare earth elements plus yttrium), titanium, vanadium, antimony, gold, and silver. These mineral deposits take the form of polymetallic nodules on the seabed, cobalt rich ferromanganese crusts on seamounts and ridges swept clean of sediment accumulation, and seafloor massive sulfides formed by hydrothermal systems at geologic plate spreading centers and volcanic margins. Each of these mineral deposits form on or near the deep ocean seafloor where water depths are typically 4000 m to 5500 m and on the seamounts and volcanic arcs that rise from these depths. Commercial interest in deep sea mineral deposits and the potential for collecting or mining them began in earnest in the 1970s but has been heightened in the last 20 years as the international framework for developing these minerals in International Waters has matured that has coincided with forecasted rapid rising demand for minerals to supply energy and manufacturing needs for the green economy. Compilation reports published by academia, government, and private companies are reviewed to assemble data and assess the prospects for deep sea marine minerals in the US Pacific OCS and EEZ. Key compilations were made by the Circum-Pacific Council and USGS in the 1980s and 1990s. These, together with recent (2023) efforts by USGS to compile geochemical data from USGS affiliated marine research sampling cruises from the 1980s and 1990s, historical data maintained by NOAA National Centers for Environmental Information (NCEI), and recent publicly disclosed results from ISA contractors are used to inform the known occurrence and prospectivity for polymetallic nodules, cobalt-rich ferromanganese crusts, and seafloor massive sulfides in the US Pacific OCS and EEZ.

Feb 22, 2026

By B. M. Eiter, J. Hrica, D. R. Willmer

"Mineworkers are routinely tasked with making critically important decisions about whether or not a hazard presents an imminent danger. Researchers from the National Institute for Occupational Safety and Health (NIOSH) collected formative data to investigate mine safety professional perspectives on workplace examinations, which revealed a potential gap in how mineworkers are assessing risk. During interviews, participants indicated having processes in place for what should be done once an imminent danger situation is identified. Critically, however, they report having no systematic methodology for mineworkers to use to determine if a hazard is considered imminent danger. While this is important for all imminent danger situations (e.g., failure to lockout/tagout), it is especially important for those situations that are not immediately recognizable as imminent danger. In this paper, we identify and describe, three distinct categories of imminent danger complexity and discuss potential steps that could lead to improved identification of imminent danger situations. Finally, we identify potential practices to incorporate into risk management efforts, including feedback, communication, and specialized training to increase awareness of imminent danger situations. INTRODUCTION In recent years, the metal and nonmetal (M/NM) mining sector, as categorized by MSHA, experienced an increase in the number of fatalities occurring at mine sites. From 2013 to 2015, 69 mineworkers were fatally injured; that is twice the number of fatalities that occurred in each of the previous two years (MSHA, 2015a). As a way to address this increase, the Mine Safety and Health Administration (MSHA) issued a program policy letter (P15-IV-01) suggesting that “miners would benefit from rigorous workplace examinations conducted by experienced and trained examiners (MSHA 2015b).” The goal of workplace examinations is to find hazards in the field and mitigate them before they cause injury or death to mineworkers. While it is important to identify all hazards in the workplace, it is critically important to identify those hazards that are considered imminent danger because they require an immediate response to avoid a severe or even fatal injury."

Jan 1, 2018

By Dongjie Zhang, Fengyu Ren, Xudong Li, Yanjun Zhou, Yang Liu, Rongxing He, Jianli Cao

Based on the limiting-equilibrium analysis of roof processive caving in hanging wall caving method and the critical medium column theory, a new model of subsidence prediction caused by sublevel caving mining method was proposed in this study, considering the drawing influence and the dynamic process of filling granular media. Meanwhile, the distribution rules for lateral pressure with different orebody dip were studied under drawing ore, and subsequently complemented the model. This model indicated that the surface subsidence scope decreased as the unit weight of crack rock and the orebody dip increased. In addition, the height of critical medium column showed a decreasing trend as cohesion of rock mass, the internal friction angle and the unit weight of rock mass. Also, the method of predicting the scope of surface subsidence in the Dabeishan Iron Mine was applied. The results showed that the relative errors are less than 9% and the prediction method could be used in practical application.

Feb 24, 2022

By D. J. Boron, R. Kollrack

Introduction The US has the largest total (364 Gt, or 401 billion st) and recoverable (182 Gt, or 201 billion st) coal reserves in the world (Steam/Its Generation and Use, 1978). However, progressive coal use in this country has been hampered by environmental constraints, such as restrictions on sulfur dioxide, nitrogen oxides, and particulate emissions. Since the promulgation of the Environmental Protection Agency (EPA) New Source Performance Standards (NSPS), it has become apparent that all US coals will require sulfur removal to comply with the new sulfur dioxide emission levels. If more stringent emission standards are imposed, through pending acid rain legislation or amendments to the Clean Air Act, it is likely that the coal industry, and the industrial and utility sectors will look increasingly toward the development of new and advanced coal cleaning technologies to continue and promote the use of coal. Table 1 summarizes the EPA NSPS for sulfur dioxide emissions. Fortunately, the basis for determining sulfur dioxide removal is the Btu and total sulfur content of the run-of-mine coal. Thus, credit is given for any sulfur removed before combustion, e.g., through physical coal cleaning. Unfortunately, physical coal cleaning alone may be unable to produce a compliance coal with respect to the EPA NSPS. Therefore, all industrial and utility coal-fired boilers will require post combustion gas cleanup, e.g., flue gas desulfurization (FGD), to comply with the new regulations. Table 1 - EPA NSPS for SO2 Emission Category SO2 Content of ROM Coal SO2 Reduction Required 1 0-2 Ib/M Btu 70 2 2-6 Ib/M Btu To 0.6 Ib/M Btu (70% to 90%) 3 6-12 Ib/M Btu 90% 4 12 Ib/M Btu To 1.2 Ib/M Btu Alternatives to post combustion gas cleanup, such as staged combustion, lime and coal injection, fluidized-bed combustion, and chemical coal cleaning, are currently under development. Of these, chemical coal cleaning offers the advantages of providing (1) high quality fuel for combustion (low sulfur and ash, high Btu, and attenuated product variability); (2) a solid fuel product for use in retrofitted gas and oil boilers; and (3) a solid fuel product with multiple end uses, e.g., internal combustion engines, carbon electrodes, coke, or chemical feedstock. Gravimelt process In the Gravimelt process, 1.4 mm x 0 (14 mesh x 0), physically beneficiated coal of about 5% moisture is fed into a 3401 to 3901 C (644 ° to 734 ° F) molten bath of sodium hydroxide and potassium hydroxide. Organic and pyritic sulfur and most of the mineral matter in coal react with and are dissolved in a molten mixture of potassium hydroxide and sodium hydroxide. The reacted coal sulfur is converted to alkali sulfides and polysulfides, whereas the mineral matter is apparently converted to alkali-aluminum silicates and other byproducts that are water and acid soluble. Coal residence time is 60 to 240 minutes. The sodium hydroxide to potassium hydroxide ratio is about 9:1. The total hydroxide-to-coal ratio is no less than 10:1. The specific gravity of the caustic melt is about 1.8 g/cm3 . Thus, coal is buoyant in the bath, and insoluble mineral matter with density greater than 1.8 g/cm3 would sink. Reacted coal is first water-washed with an equal weight volume of water in a countercurrent mode of operation. The coal is filtered and the filtrate sent for regeneration. The coal is then acid-washed in 10% sulfuric acid. The acid-water/coal mixture is filtered to recover the final coal product, and the filtrate treated with lime to precipitate dissolved mineral matter. The precipitate is filtered from the mixture and discarded. The water is recycled to the plant. Filtrate from water-washing is treated to remove sodium sulfide. The sodium sulfide is chemically treated to produce hydrogen sulfide, calcium car¬bonate, sodium hydroxide, and other products. The hydrogen sulfide is treated to produce sulfuric acid for the acid-washing step. The calcium carbonate is treated further or discarded, and the sodium hydroxide is concentrated by evaporation and recycled to the reactor. The Gravimelt process is currently at the bench-scale stage of development. A 0.9-kg (2-lb) continuous reactor is in operation with a continuous water- and acid-washing section adjacent. The regeneration section is not developed to a meaningful extent, although key reactions have been tested in the laboratory. Process conditions, product recovery efficiencies, etc., however, have not been determined adequately and continuous regeneration operation has not been attempted. Work is now in progress to develop each section to a continuous bench-scale operation in processing coal at 9.1 kg/h (20 lb per hr). Microwave process The carbon and hydrogen in coal are relatively transparent to microwave radiation. However, water, caustic, pyrite, and other mineral matter components are strong conductors of microwave radiation energy at the proper frequency. As a result, selective heating of the noncarbonaceous materials occurs that enables the chemical reaction of sulfur and ash with caustic. Although very high temperatures may result from

Jan 1, 1987

By Yongjun Xian

The release of fluid inclusions has a strong potential for the unintentional activation of pyrite during flotation. The present study aims to characterize fluid inclusions in a natural pure pyrite. The results indicate that a certain amount of fluid inclusions exist in the pyrite. The fluid inclusions assume a variety of shapes, including long strips, oval shapes and irregular shapes, with sizes that range from a few microns to dozens of microns. From the EDS results of hollow positions that resulted from the fracture of the fluid inclusions on the pyrite surface, certain amounts of Al, Cr, C, O, Ag and Cu were clearly detected; these elements were not detected in FeS2 pyrite itself. The contents of the inclusions were released into solution when the sample was subjected to a grinding process. Under experimental conditions of 2 g of pyrite cleaned in 40 mL of pure deionized water under an inert atmosphere, the concentrations of Cu, Fe, Cl- and SO4 2- released from the inclusions reached concentrations of 3.29 × 10-6, 32.52 × 10-6, 51.57 × 10-6 and 75.90 × 10-6 mol/L, respectively. These values are significantly greater than those from the experimental nonoxidative and oxidative dissolution of the pyrite. The fluid inclusions of pyrite were, therefore, concluded to represent the dominant sources of Cu, Fe, Cl- and SO4 2- in the aqueous solution. The present investigation provides a new understanding of the source of the unavoidable metal ions in the pulp and may benefit understanding of the flotation theory and environmental geochemistry.

By Yongjun Peng, Yufan Mu

Pyrite depression in the flotation of copper ores is difficult due to the activation of Cu2+ ions on pyrite surface. In this study, the radical chain reaction involving the redox cycling of Cu(I/II) induced by sodium metabisulphite (MBS) was exploited to selectively depress the flotation of copper-activated pyrite at pH 8.0. Electrochemical measurements revealed that the presence of Cu2+ and O2 was essential to the formation of SO•− 5 through sulphite oxidation, the main entity to convert the activating species Cu(I)S on pyrite to Cu(II)-hydroxide/sulphate, causing deactivation of pyrite. The depression role ofMBS on pyrite flotation was closely associated with the type of grinding media which affected the electrochemical conditions of flotation. When forged steel was used as the grinding media, a high dosage of MBS was required to depress pyrite, but a low dosage of MBS could almost completely depressed pyrite when high chrome steel grinding media was used. This is because high chrome steel produced a stronger oxidation condition with a higher amount of Cu2+ and O2 which promoted the formation of SO•− 5

Jan 26, 2021

John C. Greenway was responsible for much of my success in the seven years from what I called the end of my apprenticeship in exploration until I entered the Army in World War I. I first met Green- way on my return from Promontorio and, as he was replacing Powell, he was to be my boss. Even at first glance you couldn&apos;t help liking and trusting him. He was tall, well built, and erect-an old Yale athlete. After college he became a captain in the Rough Riders and a friend of Theodore Roosevelt, distinguishing himself in the Cuban campaign. He made good friends in all ranks of the Rough Riders, some later becoming leaders of industry and others following Greenway where-ever he went. After the Spanish War Greenway worked for iron mining companies around the Great Lakes and when the directors decided that Calumet and Arizona needed a new manager the ones who were also prominent in Oliver Iron Mining Co. selected Greenway It was a lucky choice for Greenway and for me. He became the best manager among those who ran the big copper mines He was open-minded in encouraging discussion and even opposition-until he made up his mind. Then, in military fashion, everyone must follow his decision without question. I think this is an essential of good management. Unfortunately a few did not feel this way and they had to leave. It was characteristic of those times that respect for the boss was so great that in the 16 years in which he was one of my best friends I, like all under him, always called him "Mr. Greenway." Soon after he arrived Greenway asked the leading mine operators in the southwest, Dr. Louis D. Ricketts and James S. Douglas, son of the Dr. James Douglas who had made Phelps Dodge great, to do special work for Calumet and Arizona. I found later that the object of the study was to determine the terms on which the half-dozen Warren District properties of Calumet and Arizona were to be joined in one

Jan 1, 1976

By T. L. Barone, J. R. Patts, L. D. Patts, S. J. Janisko

"Controlling float coal dust in underground coal mines before dispersal into the general airstream can reduce the risk of mine explosions while potentially achieving a more effective and efficient use of rock dust. A prototype flooded-bed scrubber was evaluated for float coal dust control in the return of a continuous miner section. The scrubber was installed inline between the face ventilation tubing and an exhausting auxiliary fan. Airborne and deposited dust mass measurements were collected over three days at set distances from the fan exhaust to assess changes in float coal dust levels in the return due to operation of the scrubber. Mass-based measurements were collected on a per-cut basis and normalized on the basis of per ton mined by the continuous miner. The results show that average float coal dust levels measured under baseline conditions were reduced by more than 90 percent when operating the scrubber. IntroductionAirborne coal dust is a byproduct of coal production, and engineering controls exist to deal with both the respirable dust health hazard as well as the float dust explosion safety hazard. Float coal dust, smaller than 75 µm (0.003 in.) in size, can deposit throughout mine entries and propagate explosions that had been initially fueled by methane gas. The inertization of float coal dust with rock dust helps prevent a potential secondary float coal dust explosion, but a preferable course of action is to significantly reduce the hazard by removing float coal dust from the airstream before it has the opportunity to deposit on the mine’s surfaces.Since 1970, disasters due to explosions in underground coal mines have caused 201 deaths in the U.S. mining industry, including 29 deaths in a single mine explosion in 2010 (Wade, 2010; U.S. Mine Safety and Health Administration, 2015). The U.S. National Institute for Occupational Safety and Health (NIOSH) had initiated a fiveyear research project that aims to investigate methods and technologies to reduce the potential for secondary coal dust explosions by the purposeful capture and/or suppression of float coal dust prior to its deposition on the mine roof, rib and floor (NIOSH, 2013). The project aims to evaluate the efficiency of methods to reduce longwall and belt airway float dust in the general airstream as well as methods to capture it at or near the source. Prioritization is given to longwall sections given the amount of coal produced relative to continuous miner sections, but the research is open to technologies that may be adapted from one method of mining to another."

Dec 1, 2016

By S. K. Kawatra, J. A. Halt

"Low-grade iron ores are finely ground and processed to recover iron-bearing minerals. However, the iron-rich powder is too fine to be used directly in blast furnaces and most direct reduction furnaces, and must be agglomerated or pelletized into a usable product called “pellets.” Bentonite clay has traditionally been used as a binder to make iron ore concentrate pellets, but it is expensive and contaminates the pellets. Organic binders may be a viable alternative to bentonite clay. This manuscript reviews organic materials that have been used to make iron ore concentrate pellets. Included are discussions on the development of organic binders, common pros and cons to organic binder use, organic binder structure and its effects on agglomeration, and additives to organic binders.IntroductionIron ore agglomeration turns finely disseminated, low-grade iron ores into a usable product, called pellets. During pellet production, fine-grained, iron-rich minerals are liberated from low-grade ores, concentrated, and agglomerated into round balls that are thermally hardened or cold-bonded to form pellets. Pellets are then transported to blast furnaces or direct reduction operations where they are used to produce iron; iron is further refined and shaped into the wide variety of steel-based industrial and consumer products in use today.Over the years, pellet production has become increasingly more prevalent with the increased exploitation of low-grade iron ores and increased iron and steel consumption around the world. In 2010, world iron ore pellet production was 388 Mt. It could be argued that the current pellet production process has been enabled by the use of binders – practical experience has shown that it would be nearly impossible to agglomerate iron ore concentrates using rotary drums and discs without using a binder."

Jan 1, 2015

By Jon A. Hummer, Aleksandar D. Bugarski, Shawn Vanderslice, Teresa Barone

A study was conducted to examine the potential of diesel emissions control strategies based on retrofitting existing power packages with exhaust aftertreatment devices and repowering with advanced power packages. The retrofit systems, a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF), were evaluated individually using a US EPA tier 2 (ter 2) engine operated under four steady-state conditions and one transient cycle. The DOC effectively curtailed emissions of CO, and to some extent organic carbon (OC), elemental carbon (EC), and aerosol number concentration. The DPF system offered substantially higher reductions in OC and EC mass and aerosol number concentrations. Both, the DOC and DPF achieved reductions in the aforementioned emissions without adversely affecting emissions of NO2 and nano-sized aerosols. The strategy of repowering with an advanced system was examined using a US EPA tier 4 final (tier 4f) engine equipped with a cooled exhaust gas recirculation system and diesel exhaust fluid-based selective catalytic reduction system, but not with a DPF system. The tier 4f engine contributed substantially less than the tier 2 engine to the EC and OC mass, aerosol number, and CO, NO, and NO2 concentrations. The tier 4f engine was very effective in reducing aerosol mass, NO, and NO2 concentrations, but it was not equally effective in reducing aerosol number concentrations. The implementation of viable exhaust after treatment systems and advanced diesel power packages could be instrumental to the underground mining industry to secure a clean, economical, and dependable source of power for mobile equipment.

By Neil H. Bostick

This research, sponsored at Stanford Research Institute by the Grand Junction Operations Office of the U.S, Atomic Energy Commission, was an outgrowth of the concern that presently-known ore reserves may be inadequate to meet the projected demands of nuclear power reactors. The original program at SRI was to design a comprehensive geological information system and use it to store and analyze the very great quantity of data needed to estimate uranium ore reserves. Study of the problem showed that it could be solved only by use of modern electronic data processing techniques, so such a comprehensive system was designed and tested. The system test was satisfactory, but input lead time and total expense were shown to be too great for the system to be practicable for the AEC under present circumstances. Thus, based on results of the earlier research, a specialized and simplified procedure for predicting approximate uranium ore reserves was devised. The prediction is based on general geology of specific area cells of the earth, in order to provide complete volume coverage; the strata in these ores are evaluated for uranium ore favorability on the basis of a few selected criteria in order to allow rapid data input. Since the bulk of U.S. reserves are in clastic host rocks only such strata are considered in this work. This paper describes the structure and some details of the resource system and how it was tested in rn area of the western United States.

Jan 1, 1969

By G. L. Ploetz

The lanthanon compounds are becoming increasingly more important for ceramic and allied applications. As the supply increases and the cost decreases, further development of these interesting materials will undoubtedly lead to new applications and an increased demand. Recent improvements in separation processes have lead to high purity in the individual lanthanon oxides. This report includes short discussions on the mineralogy of the ores as raw materials, and on the separation processes required to produce the pure individual lanthanon oxides in useful quantities. To discuss the presently known applications of lanthanon oxides, this general review is divided into the following categories: A. Glasses, Glazes, and Porcelain Enamels. B. Refractories and Abrasives. C. Electronic Ceramics. D. Nuclear Ceramics.

Jan 1, 1960

By C. J. Newman

Prior to 1995, the smelting process at the Kennecott Utah Copper Corporation (KUCC) smelter consisted of Noranda reactors and Pierce-Smith converters. In the consideration of expansion opportunities, the existing process did not lend itself to a program geared towards processing the total output of KUCC mining and milling operations. During 1989 and 1990, a number of smelting options were evaluated. The final selection was the Outokumpu flash smelting process, coupled with the new Kennecott-Outokumpu flash converting technology. Facilities were designed and installed to process 1.0 million tonnes per year of copper concentrate, with the ability to expand to 1.2 million tonnes per year. Following the shutdown of the smelter facility utilizing the Noranda technology in May 1995, the flash smelting furnace commenced operation in June with the flash converting furnace startup following a few weeks later. The smelter has achieved design production targets and environmental goals. Current operating rates are at or above design rates for concentrate and matte processing. Emissions are lower than the permit levels and equate to less than 3.5 kg of S02 per tonne of copper. This paper outlines the design, construction, startup and the first two years of operation of the modernized KUCC smelter.

Jan 1, 1998

By J. B. Malcolm

The discovery of tungsten-bearing quartz outcroppings in Vance County, N. C., by the Hamme brothers in 1942, made international news in the mining industry and was, in fact, one of the major ore discoveries made in the U.S. during the last 25 years. Operations began at the Hamme mine in 1942, but after 16 years of successful operation, the mine was closed down in 1958 under adverse market conditions. By that time, it had produced nearly 20 million lbs of metallic tungsten. Because of the square-set timber mining method then in use, mine operating expenses were high, actually representing 78% of the total operating expenses at the property. In timber work alone, 160 men were employed. Approximately 500,000 bd ft of timber were placed monthly at a direct supply cost of $1.00 per ton of ore mined. Late in 1959, following a slightly improved position in the tungsten market, company management decided that, by changing the mining method, the operation could be economically feasible. The major premise in this decision was that a reduction of from 25 to 30% of the mining costs could be achieved by the conversion of the mining method from square-sets to horizontal cut and fill. Reopening of the mine began in February 1960, Full production has now been reached and overall mine productivity has been doubled.

Jan 1, 1962

Maximizing margins in competitive markets demands superior productivity. Unfortunately, management systems developed early this century for other industries often drive counterproductive behaviors choking mining productivity. Many executives and managers waste valuable time and effort relying on simply training and communicating to improve managerial practices and attitudes. In covering practical human behaviour, the paper explains why this fails -and explains how to use systems to successfully drive improved managerial practices and attitudes. It highlights use of modern performance Measurement, Analysis and Reporting systems to drive behaviors and improve margins -without capital investment -and make executive and managerial work easier and more effective.

Jan 1, 1999

By Saul J. Escalera

Mechanisms involved in the depression of the sulfides: pyrite, chalcopyrite, galena and sphalerite with potassium permanganate have been investigated. Flotation tests were conducted using potassium amyl xanthate, Z-6, and pine oil in the absence and presence of potassium permanganate at around pH = 6. 5 naturally yielded by the sulfides in the pulp. On the basis of crystal chemistry considerations, the amount of xanthate adsorbed by the sulfides depends on the amount of sulfur and metal ions present on the surface; thus, the avidity of the sulfides for xanthate should increase in the order: sphalerite C chalcopyrite 4 galena 4 pyrite, and the ease of depression response to the permanganate action should be in the same order. Depression of the sulfides in the system occurs primarily due to the removal of the collector ions by the permanganate ions to form manganese dioxide and dixanthogen according to the reaction: 3 M(RX)2 + 2 Mn04 + 4 H20 2 ? MnO2 + 3(RX-XR) + 3 M+2 8OH where M represents the metal ion, RX the xanthate ion and (RX-XR) the dixanthogen molecule. Results seem to indicate that the permanganate ions play a triple role in the system: (1) they convert xanthate ions into dixanthogen, (2) they further oxidize the mineral surface and (3) if present in excess, they may oxidize the xanthate beyond the dixanthogen stage with the formation of CO2, H20 and SO4. All sulfides, except for chalcopyrite, showed a depression response in the order predicted regardless of the order of addition of xanthate and permanganate reagents. Chalcopyrite did not depress as easily; this behavior may be due to the avidity of the colloidal MnO2 to adsorb Cu+2 ions on its surface, this would destabilize the colloid making it coalesce with the formation of a layer of precipitated MnO2 on the surface of the mineral. The presence of this layer would prevent further action of the permanganate ions on chalcopyrite.

Jan 1, 1970