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By James P. Cooney

What is required for the mining industry to grow and prosper in a politically challenging world? The answer to this can be summarized as “the industry’s three priorities.” The first priority is gaining access to the world’s mineralized jurisdictions. The second is establishing a measure of security and predictability in government treatment of mining. Confidence in the stability of the fiscal and legal framework within which mining operates is necessary to encourage the investment of large amounts of capital in mine development. The third priority is sustaining the industry’s welcome during the long term in those jurisdictions worthy of investment.

Jan 1, 1996

By Michael R. Smith

Barrick Goldstrike Mines Inc.’s Betze open pit is located at the north end of the Carlin Trend, in Eureka County, NV. Ten open pit gold mines exist on the trend, which strikes northwesterly, through the north end of Eureka County and into Elko County (Fig. 1). The final pit will be about 2440 m long x 1550 m wide (8000 x 5100 ft), elongate in a west-northwesterly direction and about 425 m (1400 ft) deep. The pit straddles the Barrick-Newmont Gold Co. property boundary. History The first hole at the Goldstrike Mine was drilled in 1962. Between 1963 and 1964, 17 shallow holes were drilled with little encouragement, in view of the price of gold at $1.12/g ($35/oz). From 1962 to 1975, several different companies explored the Goldstrike property. In 1975, Pancana Industries acquired the property. In 1976, Pancana’s exploration efforts found sufficient gold mineralization to initiate heap leach production. In 1977, Pancana formed a joint

Jan 1, 1994

By J. C. Norman

The United States was the world’s largest producer and consumer of boron compounds during 1995. According to estimates from the US Geological Survey(USGS), boron mineral concentrate and chemical production in the United States totaled an estimated 1.1 Mt(1.2 million st) yielding 602 kt (663,000 st) of B2O3 for an estimated value of $462 million. This level of production exceeded 1994 revised production figures by about 9%. The United States continued to provide nearly all its own boron supply while maintaining a strong position as a source of sodium borate products and boric acid to foreign markets. During 1995, about 900 people worked in domestic boron mines and plants, about the same as in1994. USGS estimated total world production of boron during 1995 to be about 3 Mt (3.3 million st), yielding about 1.6 Mt (1.8 million st) of B2O3. World production in 1995 was about equal to revised 1994 levels.

Jan 1, 1996

By Jin Dai, Xianwen Geng, Hao Liu, Pu Wang

To investigate how deformation failure occurs in roadways surrounding rock, the relationship between cohesion and plastic shear strain of the strain softening model and the equation for calculating the shear strain of a rock mass in the ultimate elastic state are derived. On this basis, the equality relationship between the built-in maximum shear strain increment and cohesion of FLAC 3D was established to give a more intuitive picture of how the cohesion of the roadway surrounding rock changes. The cohesion attenuation and deformation of the surrounding rock are analysed. The results show that significant deformation in the roadway surrounding rock was caused primarily by the development of large areas of highly softened plastic rock masses towards residual strength. Taking the floor overhead-mining roadway under different rock pillar thicknesses (RPTs) in the Xinglongzhuang Coal Mine as an example, the results demonstrate that investigating the cohesion distribution inside the roadway during mining operation can provide a more intuitive, more accurate description of the degree of failure of the surrounding rock at any point of the roadway, as well as the overall failure range of the surrounding rock. The simulation agrees well with the field monitoring result and seems to be more practically useful than simply analysing the coverage of shear plastic zones. Based on the failure range and degree of roadway surrounding rock with different RPTs, three support schemes are designed. Classified support was implemented for roadways under different RPTs, which realizes the effective control of roadway surrounding rock.

Jan 16, 2022

By C. Dirscherl

"Declining ore grade, leading to increased material transport and plant throughput requirements, is one of the major challenges in the current mining environment. This is accompanied by rising energy and labor costs, decreasing plant productivity and the requirement for highest plant availability. Siemens’ answer is the latest gearless drive technology for grinding and conveying. Gearless drive solutions are surpassing the mechanical limits of conventional drive systems serving to utilize the principle of economies of scale. By elimination of various components of the drive train, the maintenance activities and spare parts inventories are reduced. The advantages are culminating in the incomparable availability of the Siemens’ gearless drive technology of 99.46 to 99.71 percent — as confirmed by real operational data from the Antapaccay Mine in Peru. It was the first plant worldwide to use gearless drives for both applications.The gearless principleThe principal idea behind a gearless drive system is to reduce the number of components and diversity of parts, especially those components that are at the edge of current manufacturing or power limits are eliminated. The used equipment provides the possibility to scale up and increase the power transmitted to the driven machine. This finally results in a possible increase of throughput respectively transported or processed material.In order to apply this principle of simplification, the components of a conventional drive system are examined. They consist of:• Driven equipment (mill, conveyor, slurry pump).• Components altering the rated speed (gearboxes, girth gear/pinion).• The electric motor.• Starting devices for the motor (VSD, CCV, LRS, clutch), which are necessary because a direct across-the-line start of high power motors with load would result in a significant drop in the line supply voltage.• Alternatively a variable speed drive (VSD) or cycloconverter (CCV) to utilize the possibility of speed variation during operation.• The electrical supply system (cables, switchgear, transformers, protection equipment)."

Jan 1, 2015

By Joe B. Rosenbaum

Fine-sized mineral wastes discarded by ore milling plants require stabilization to prevent air and water pollution. Methods devised for achieving this stabilization include physical, chemical vegetative, and combination procedures. Although vegetative reclamation is preferred to physical and chemical stabilization, it is difficult to achieve because the wastes are sterile, contain deleterious inorganic salts, and lack the essential nutrients and physical characteristics required for sustaining vegetative growth. Nevertheless, recent research has developed methods for producing vegetative growth on all but excessively acidic, basic, or saline tailings at costs ranging from $100 to $650 per acre. This report summarizes effective procedures developed for vegetating average tailings, the cost differential between the various methods, and suggests procedures that may be applicable for achieving stabilization of pyrite-containing wastes that may oxidize and become excessively acidic. The use of buried layers of sewage sludge to prevent this acidification is discussed.

Jan 1, 1972

By S. K. Samal, B. Mishra, M. K. Mohanty, S. C. Mishra

Steelmaking industries consume the majority of chromium and manganese ferroalloys to impart several properties in steel and also for other purposes. The quality of ore governs the process kinetics as well as the process economy of the ferroalloy industry. The present study demonstrates the thermal transformation behavior of chromite and manganese ores with varying compositions. Simultaneous thermal analysis (DTA/TG) is employed for such ore samples where the transformation of mineral phases is correlated with the thermogram characteristics and quantified. Phase, microstructure, and compositional analysis results of individual ores corroborated with thermal analysis are in good agreement. Chromite samples are ferruginous with goethite and gibbsite contents, whereas manganese ores vary in composition and also exhibit multiple and/or overlapping transformations.

Jan 21, 2021

By D. Pearson

About 15,000 tonnes of zinc per year is present in the dusts and fumes produced in electric arc and BOS steelmaking, secondary copper refining and brass ingot making. Apart from the use of some copper-smelter fumes for zinc chemicals manufacture, zinc is not recovered and their disposal by landfill entails some risk of pollution by leach-out. The paper describes processes for recovering the zinc based on leaching and electrowinning. It was shown that the procedures normally employed for purifying zinc-electrolytes derived from primary sources are sometimes ineffective for secondary materials. Alternative process routes are proposed. Source materials were leached with acidic or alkaline reagents and solvent extraction was employed for electrolyte purification in addition to the usual techniques involving precipitation. Examples of integrated flow sheets for specific source materials are presented.

Jan 1, 1980

By G. M. Wilemon

The U.S. Bureau of Mines has conducted investigations on extracting phosphate values from wastes generated during the mining and beneficiation of phosphate matrix. These wastes may contain up to one third of the phosphate originally present in untreated ore. Samples of wastes were air-dried and leached using 93 pct sulfuric acid in the presence of methanol. Evidence for the formation of a calcium sulfate hemihydrate coating that hinders complete dissolution of phosphate is presented. Solid-liquid separations were enhanced when flocculation was effected using poly(ethylene oxide) (PEO) in conjunction with hydroxypropyl cellulose (HPC) or hydroxyethyl cellulose (HEC. A conceptual flowsheet for a proposed process using an acid-alcohol leaching technique is presented.

Jan 1, 1990

By Keith A. Heasley

At this point in time, approximately 800 M tonnes (880 M tons) of coal are mined each year in the United States. Forty percent of this coal or approximately 320 M tonnes (350 M tons) is taken from underground coal mines, and from this subtotal 16% or 50 M tonnes (55 M tons) is from longwall panels (1). If, for the sake of argument, an aver- age extraction thickness of 1.5 m (5 ft), an aver- age extraction ratio of 50 percent and an in situ density of 1360 kg/ms (85 lb/ft3) for this coal are assumed, then the 320 M tonnes (350 M tons) of underground coal translates to over 310 km2 (76,000 acres) that is undermined each year. Con- sidering that the total U.S. production of under- ground longwall coal to date is approximately 345 M tonnes (380 M tons), then a total of approximately 165 km2 (41,000 acres) (considering 100% extraction) has been directly undermined by longwall coal production in the United States. If the angle-of- draw is considered, the total area affected by longwall subsidence in the United States is probably twice the above value or 330 km2 (82,000 acres) . In the future, a number of other miscellaneous factors seem likely to multiply the number of potentially damaging situations that occur due to longwall coal mining. First, the overall production of coal in the United States is expected to gradually increase. This factor is further com- pounded by both the fact that the percentage of the overall production due to underground mining is bound to increase, since the vast majority of U.S. reserves (68%) are only recoverable by underground methods, and the fact that the percentage of the underground production of coal that is recovered by longwall mining is drastically increasing (1). Finally, as the nicest underground reserves are depleted, the remaining reserves will tend to be deeper, which increases the affected surface area, and under denser population concentrations, which increases the likelihood and severity of possible damages. Overall, considering the number of factor which are biased towards increasing the amount of undermined acreage, it appears that there must certainly be a corresponding increase in the number of possible damaging situations due to longwall-induced, ground subsidence.

Jan 1, 1986

By S. A. Smith-Hamm, E. A. Sarver, A. S. Cox

Appalachia is an increasing concern, as unnaturally high TDS and/or associated specific conductivity (SC) may contribute to deteriorated stream ecosystem health. The aim of this preliminary study was to explore the efficacy of accelerated leaching as a means of minimizing long-term TDS/SC generation by problematic overburden materials. Five spoil samples were collected and leached using simulated rainwater solutions under ambient and acidified pH conditions. SC and pH were monitored during each leach cycle, and inductively coupled plasma-mass spectroscopy (ICP-MS) was used to determine how leaching conditions affected the release of specific ions. This paper highlights the results of both jar and column leaching tests. Among the most significant findings was that for certain spoil materials, the SC in the leach column effluent was effectively reduced when the spoil was first leached with acidic rainwater followed by ambient rainwater, as opposed to leaching with ambient rainwater alone. This suggests that accelerated leaching might aid in the long-term stabilization of some materials.

Jan 1, 2015

By D. Anthony, R. A. Williams, R. Raponi

Barrick Gold Corporation in conjunction with SNC Lavalin Engineers and Constructors have developed basic engineering design for counter current decantation thickener (CCD) plants capable of processing 44 000 t/d. To achieve this throughput in a single train, the largest high-rate thickeners installed to date have been utilized in concert with large process slurry and solution transport systems. Process reliability and plant operability and maintainability have been carefully considered in order to develop a practical, yet cost effective design. The design also incorporates the challenges associated with installation of large equipment and structures in a remote location, with a climatically hostile environment, situated in a high seismic activity zone.

Jan 1, 2002

By S. T. Murray

The European industrial minerals industry and its markets are largely self-sufficient. The companies who are members of the Industrial Minerals Association (IMA-Europe) number around 150 contributing 5 billion Euros to the EU?s GDP and range in size from global publicly quoted corporations to small family owned private companies. Their means and capability to implement sustainable development vary considerably. However the leading companies provide an excellent set of best practices, which IMA as a trade association with recognised core competencies in the field of sustainable development is ideally placed to promulgate throughout its membership. As an active participant in the EU Voluntary Scheme for SDI reporting IMA is not only working to increase the level of response to the SDI questionnaire but is also developing with its members a new sustainable development charter which its members will voluntarily adopt as a guiding principle for their implementation of sustainable development This work will be a consultative process involving all IMA?s section members as well as other trade associations, NGOs and MEPs. Public awareness of the benefits of minerals and their contribution to sustainable development has been raised by IMA?s awareness campaign now being followed by a more targeted programme aimed at MEPs. Further work in the future will consider product stewardship and life-cycle analysis. IMA is already positioning itself with the help of its members to assimilate the minerals industry of the accession territories in the sustainable development process.

Jan 1, 2003

By Dean R. Gehring

Creating projects to reach a goal is not new to American industry. In fact, all major construction projects, from skyscrapers to bridges, are completed using similar project management techniques. However, modern project management is relatively new. It was not formalized until 1962, when NASA and the US Department of Defense recognized the need to develop uniform project management procedures throughout the aerospace industry (Moder, Phillips and Davis, 1983). This management method was not introduced to the mining industry until the early 1970s (Britton, 1983). Project management typically follows an organized, four-stage process —definition, planning, implementation and control.

Jan 1, 1996

By S. Deming

Coal is China's main source of energy. In 1988, 76.1% of commercial energy consumption was supplied by coal. To provide a rational utilization of its coal resources, China has paid considerable attention to coal preparation over the last 10 years. In 1980, there were only 105 washeries treating about 100 million tonnes of coal, but by 1988 there were 151 washeries treating 171 million tonnes per year. This paper describes the development of China's coal preparation industry; its growth, the equipment, and the technology. Statistics and information on the current status of the industry are also be presented.

Jan 1, 1991

By J. M. Mutmansky

This paper outlines the results of a study of opinions of practicing engineers concerning the value of environmental engineering courses in a mining engineering curriculum. One hundred engineers with significant experience in mining-related engineering work were carefully chosen. Of the sixty-seven responses received, about half were from mining engineers and half from environmental engineers. The results of the survey are outlined in detail. The number and type of courses recommended by the respondents are summarized as well as the specific topics recommended for inclusion in a mining engineering curriculum. The survey form also asked for the stages in the mine life when environmental experts were needed and the percentage of environmental engineering performed by outside experts for many mining-related environmental tasks. The results of this line of questions are provided. Finally, the paper offers a comparison of the results for environmental engineers and mining engineers and analyzes the differences.

Jan 1, 2001

By K. J. Henderson

INTRODUCTION Shrinkage mining at Inco Ltd.'s Crean Hill mine can best be defined as a horizontal breasting method utilizing the broken ore for the mining floor and to provide wall support, with draw from a series of boxholes or draw¬points at the base of the stoping block. In choosing to shrink a given block of ore, the initial investigation centers on the ore configuration and grade, the expected ground conditions in the stoping area, the expected profit compared to alternative mining methods, the future production requirements, development lead time, the availability and type of equipment in the area, and the availability of experienced miners. These factors are weighed against other mining methods and shrinkage mining is chosen when the advantages outweigh the dis¬advantages. These will be discussed in more detail later. At Inco Ltd.'s Crean Hill mine, shrinkage mining makes up 17% of total mine production and is decreasing due to the advent of advanced blasthole techniques, notably in-the-hole drilling. Shrinkage is an adaptable mining method that is currently employed in narrow irregular ore zones, as undercuts for in-the-hole blast¬hole stopes, in ore bodies that do not extend from level to level, and in areas where quick production is required with a minimum of capital outlay or minimum develop¬ment. Two major types are currently in use which are classified on the basis of type of draw system employed. These are the utilization of load-haul-dump (LHD) equipment drawing from drawpoints, and the slusher and train method drawing from boxholes into a slusher trench and loading into a train. A third method being phased out is drawing from chutes directly into a train. In all three methods the actual stoping operation remains the same. In the initial planning of a mining block, the ore body is first located using an exploration diamond drill¬ing program. This is essentially done at a 130-m (400¬ft) spacing and it gives an indication of the amount of ore, grade of ore, the configuration of the ore body, as well as other geological features such as ground condi¬tions which will affect future mining. This drilling is done from an exploration drift 165 m (500 ft) long in the hanging wall and covers a vertical extent of 330 to 670 m (1000 to 2000 ft). However, these data are not accurate enough for detailed planning. When the de¬cision has been made to mine, a preliminary develop¬ment drill drift is driven in such a position that it can serve the dual purposes of allowing the ore body to be drilled off in detail, or of later serving as a haulage or access drift. Diamond drilling from this drift is usually on a 15-m (50-ft) grid spacing and gives adequate information for detailed planning. Utilizing the drill data, a decision is made on the mining type. For a shrinkage operation, the stoping block is ideally 49 m (150 ft) in length and a maximum of 13 m (40 ft) in width. Lengths of 65 m (200 ft) are considered a practical maximum because of the length of time the back of the stope remains open during the min¬ing of a cut. A minimum length of 13 m (40 ft) is used because the amount of time spent in opening a new cut increases in comparison with the total stoping time. The maximum width of 13 m (40 ft) is used because ex¬perience with the ground indicates that generally stope backs tend to be unstable over greater widths. However, widths of 33 m (100 ft) have been mined. A minimum width of 5 m (15 ft) is used to allow an effective draw, but in unusual cases, a width of 3 m (10 ft) has been mined successfully. The dip of the ore should not be less than 1.04 rad (60°). Angles flatter than this will not pull properly resulting in inefficient mining because of ore hang-ups on the footwall side of the stope and the need for large stagings on the hanging wall. In considering shrinkage, mining ground conditions play an important role. Strong shearing, cross faulting, or dikes are avoided. These usually cause dangerous mining conditions and an alternative safer mining method which will give adequate support to these adverse ground conditions is employed. Production requirements are taken into considera¬tion when planning a shrinkage mining program. In it¬self, shrinkage mining is capable of producing ore in a relatively short time with little capital development. If quick production is required, this method can produce ore rapidly as all that is required is that the draw system be completed and the miners with jacklegs and stopers produce a limited amount of ore. The obvious disadvan¬tage is that not all the ore broken can be pulled from the stope immediately. However, a mining horizon with sev¬eral shrinkage stopes in different stages of production can adequately maintain scheduled tonnage require¬ments, the cycle being stopes under development, stopes actively mining, and stopes completed and pulling. When the decision has been made to use shrinkage mining in a given block, the haulage and draw system is driven. The proximity of the orepass system dictates whether the system is to be a LHD operation or a slusher trench operation. If the orepass system is in close prox¬imity to the stoping block, LHD equipment is employed because of its ability to operate efficiently over short haulage distances. A long tram to the orepass usually dictates a slusher trench operation with haulage by train. Internal orepass systems are used effectively with LHD equipment with a load-out and retramming taking place on a lower horizon. In addition, stoping blocks in older areas of the mine are developed track because of the capital cost involved in converting an existing level to trackless mining. DRIFT DEVELOPMENT USING LHD EQUIPMENT The haulage drift for a draw system using LHD equipment is driven parallel to the ore body in the foot¬wall at a sufficient distance to allow an 11.5-m (35-ft) drawpoint to be driven into the ore (Fig. 1). The actual position of the drift depends entirely upon the ore con¬figuration and the drift size depends on the equipment to be used. Drift sizes of 4.6 x 4.1 m (14 x 121/2 ft) for an St-4 and 3.8 x 3.6 m (111/2 x 11 ft) for an St-2 meet company and government clearance standards and allow sufficient space to accommodate a ventilation pipe. The

Jan 1, 1982

By M. V. T. Da Silva, J. C. Harrison

Eldorado Gold Corporation of Vancouver, B.C. owns and operates three gold mines. The São Bento underground gold mine in Minas Gerais State, Brazil produced 105,907 ounces in1997. The La Colorada and La Trinidad open pit, heap leach mines in Mexico produced over 83,000ounces in 1997. With a deteriorating gold market plaguing the industry throughout 1997 Eldorado had to take critical measures at each mine to enhance gold production while lowering cash operating costs. Each mine had its own unique problems to confront. This case study will discuss three distinct courses of action taken at the three mine sites.

Jan 1, 1999

By Wayne W. Murdy

Peru is a mineral hot spot in the world today. Newmont is in the exploratory phase of this mining cycle, a phase full of optimism and expectations. But exploration is high risk. There will be successes but also failures. Many foreign companies will come and go. But it is the responsibility of the mining industry leadership of Peru and the government to continue to foster an environment conducive to investment. This is the time of year companies begin planning their next annual report. Last year, Newmont’s was called “new horizons.” It highlighted the company’s global expansion into Peru, Uzbekistan and Indonesia. Now, projects that were only on the horizon a year ago are moving into production. So “turning opportunity into gold” may be this year’s theme.

Jan 1, 1996

By M. R. Shahan, C. E. Seaman, S. E. Mischler, T. W. Beck

"Float dust deposits in coal mine return airways pose a risk in the event of a methane ignition. Controlling airborne dust prior to deposition in the return would make current rock dusting practices more effective and reduce risks of coal dust-fueled explosions. The goal of this NIOSH study is to determine the potential of open-air water sprays to reduce concentrations of airborne float coal dust (<75 µm diameter) in longwall face airstreams. This study evaluated unconfined water sprays in a featureless tunnel ventilated at a typical longwall face velocity. Experiments were conducted for two nozzle orientations and two water pressures for hollow cone, full cone, flat fan, air atomizing, and hydraulic atomizing spray nozzles. Gravimetric samples show that airborne float dust removal efficiencies averaged 19.6 percent for all sprays under all conditions. The results indicate that the preferred spray nozzle is operated at high fluid pressures to produce smaller droplets and move more air. These findings can be used to select sprays and design spray arrays to control airborne float dust over the entire longwall ventilated opening. INTRODUCTION Coal mining processes produce airborne dust that naturally deposits on the floor, roof, and ribs of mine airways. These fine dust particles, termed float coal dust when smaller than 75 microns in diameter, are deposited in return entries of coal mines and can be re-entrained by pressure waves induced by methane-air explosions (Rice et al., 1911; Nagy, 1981; NIOSH, 2006). These particles are also those most likely to participate in coal dust-fueled explosions, which can potentiate and propagate explosions resulting in extensive damage. In order to meet compliance requirements of at least 80 percent incombustible content in the composition of material deposited in mine entries (CFR, 2016), coal mines apply an inerting agent, specifically, rock dust (Harris et al., 2009). Should methane be present in the mine atmosphere, the required fraction of incombustible content is further increased by 0.4 percent for each 0.1 percent methane. The removal of airborne float coal dust (AFCD) prior to deposition is an approach intended to make current rock dusting practices more effective by increasing the proportion of inert material to combustible material, resulting in a lower risk of coal dust-fueled explosions. Water sprays are both effective and widely accepted as a method for controlling underground coal mine dust. In fact, water sprays are considered to be the most economical and technically feasible means of reducing dust concentrations in underground coal mines (Courtney and Cheng, 1977; Barker and Humphreys, 1996). Sprays are used in several ways to control dust in mining processes: inhibiting dust formation, immobilizing dust to prevent it from becoming airborne, and capturing airborne dust (Cheng, 1973). Reductions in airborne dust concentrations have frequently been attributed to inertial impaction between water droplets and dust particles, forming larger agglomerates which then quickly precipitate out of the airstream (McPherson, 1993). Inertial impaction activity is generally accepted as the major capture mechanism for airborne particles larger than 0.5 µm in diameter. It is this mechanism that is evaluated in this study."

Jan 1, 2017