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By Brian G. White

The Coeur d'Alene Mining District of northern Idaho is remarkable for its number of large ore bodies and for the amount of its historical production of lead, zinc and silver (Fig. 1). Since veins were first discovered in 1884, more than 127 Mt (140 million st) of ore have been produced from narrow, high-grade veins. Mining continues at the Lucky Friday, Galena and Sunshine mines (Fig. 2). All have been in production for decades. At these mines, more efficient mining and exploration techniques have reduced costs while adding significant new reserves. Even the old Bunker Hill Mine, where ore was first found in 1875, continues operation on a limited basis, partly involving production of world-class pyromorphite specimens. Until recently, the Coeur Mine was also a profitable silver producer. Other large producers have included the Star-Morning, Hecla, Page, Standard-Mammoth, Hercules and Gold Hunter mines (Fig. 2). The first deposits were discovered by prospectors who spilled over from the Murray gold mining district, 24 km (15 miles) to the north. The Bunker Hill Mine was founded the year after the first veins were discovered. Bunker Hill has now operated for more than 100 years. Production includes 2.3 Mt (2.6 million st) of lead, 1.1 Mt (1.2 million st) of zinc and 4.1 kt (132 million oz) of silver. Total district production through 1996 (Springer, 1997) amounted to 7.3 Mt (8.1 million st) of lead, 3 Mt (3.3 million st) of zinc, and 34.5 kt (1.109 billion oz) of silver. This record establishes the district as the largest recorded producer of silver in the world, while also yielding major quantities of lead and zinc. Only Potosi, Bolivia, may have produced more silver, although records are unclear. Despite the district's longevity, historic production and current activity, the published literature on the district lags behind with regard to recent concepts of district geology. The most recent comprehensive US Geological Sur- vey (USGS) bulletins (Hobbs et al., 1965; Fryklund, 1964) are dated. Much research in the last half century has been short-lived or geographically restricted because the district is large and its geology is complex - and even this research tends to remain unpublished. Thus, it has been difficult for in- [ ]

Jan 1, 1998

By T. Qiu

"The purpose of this study is to investigate the effect of the dosage of sodium hypochlorite as activator on the flotations of depressed marmatite and depressed chalcopyrite, with a focus on activation-flotation kinetics. Four flotation kinetic models were applied to test data using 1stOpt statistical analysis software to estimate the relationships between the maximum flotation recovery rates for the depressed marmatite and depressed chalcopyrite, the flotation rate constants and the sodium hypochlorite dosages. Within the range investigated, the highest flotation performances of depressed marmatite and depressed chalcopyrite were obtained at 2.5 mL/L sodium hypochlorite with zinc recovery rate of 93.8 percent and 3 mL/L sodium hypochlorite with copper recovery rate of 94.6 percent, respectively, after four minutes of flotation. A second-order model with rectangular distribution of flotabilities gave the best fit to test data collected at various sodium hypochlorite dosages. For the highest flotation performances of depressed marmatite and depressed chalcopyrite, the respective equations of their flotation models were derived and presented.IntroductionCyanidation tailings are the solid residues generated by gold plants that use cyanide to extract gold (Lv, Ding and Qian, 2015; Zhang, Li and Yu, 2013). Because of increasing demand for gold, the Chinese gold industry has developed rapidly, with production amounting to 451.799 tons in 2014, an increase of 5.5 percent from 2013. Chinese gold production has been the highest in the world for eight consecutive years. As a result, more than 2.45 million tons of cyanidation tailings are estimated to be discharged into tailings ponds every year (Li et al., 2010; Lv, Ding and Qian et al., 2015; Wang et al., 2015; Zhang, Li and Yu, 2013; Zhang, Li and Yu, 2012), and approximately 300 million tons of cyanide tailings are stockpiled in China, with the potential to cause serious environmental pollution as well as death to wildlife (Adams and Lloyd, 2008; Donato et al., 2007; Hewitt, Breuer and Jeffery, 2012; Velasquez-Lopez et al., 2011; Stephen et al., 2009; Zagury, Oudjehani and Deschenes, 2004). Concerns over cyanidation tailings are not exclusively environmental but also economic, as tailings occupy considerable land area, and tailings storage facilities increase the production costs of gold enterprises (Donato et al., 2007). Tailings often contain other valuable metals such as zinc, lead and copper. For example, the cyanidation tailings of Gaoyao Hetai Gold Plant in Guangdong Province contain 2.5 percent copper (Cu), 0.31 percent lead (Pb), 0.23 percent zinc (Zn) and 15.36 percent iron (Fe) (Shi, 2008), and the tailings of Tianshui Gold Plant in Gansu Province contain 1.94 percent Cu, 5.96 percent Pb, 0.27 percent Zn and 24.62 percent Fe. Cyanidation tailings have therefore been increasingly viewed as a secondary resource rather than waste."

Jan 1, 2016

By J. R. Parry

Over the past several years, computerized financial models have been an important part of Newmont's strategic planning process. Two applications will be discussed in this paper: a general purpose financial model of Newmont, and a detailed operational/financial model of Magma Copper Company. Newmont?s general purpose financial model was developed using Lotus 1-2-3. It was designed to aid management in assessing the financial consequences of investment and financing decisions associated with long-term strategic planning by simulating the consolidated effect from individual transactions. Not only is the model capable of assessing the sensitivity of specific decisions to changes in the external economic environment (i. e., commodity prices, interest rates, inflation and exchange rates), it can also evaluate the effect from operating and financial decisions, including changing production levels and cost structures at individual operating units as well as simulating several types of transactions, including equity and debt issues, acquisitions and divestitures. The analysis of Magma Copper Company required the development of a detailed operating and financial model of the Company. The model was developed using IFPS in the corporation?s UNISYS (then Burroughs) B7900 mainframe computer and included separate pro forma financial statements for each of San Manuel-Pinto Valley's mines and concentrators, as well as Magma's smelting and refining operations. The outcome of this analysis was the decision to merge Magma Copper and Pinto Valley Copper Corporation, and to recapitalize the new corporation in order to provide funds for a retrofit and expansion of its Arizona smelter and expansions of its refinery and SXEW facilities.

Jan 1, 1989

By D. A. Norrgran

The recent development of rare earth permanent magnets has revolutionized the field of magnetic separation. The advent of rare earth permanent magnets in the 1980's provided a magnetic energy product an order of magnitude greater than that of conventional ferrite magnets. This has allowed the design of high-intensity magnetic circuits operating energy free and surpassing the strength and effectiveness of electromagnets. New applications and design concepts focused on the mineral and metal processing industries have evolved. This technology also led to the development of various magnetic separators specifically designed for mineral processing applications. Applications which were not previously considered are now being applied to primary mineral upgrading and recycling and secondary recovery.

Jan 1, 1993

By R. Hardy

LaModel is a boundary-element program capable of calculating the displacements and stresses in thin bedded deposits such as coal, salt, or potash. Throughout its history, it has continually been upgraded in order to expand analysis detail and stay current with the latest advances in computer technology. The most recent enhancements include: an increased grid size capability, a significant increase in the speed of the automatic grid generation using an AutoCAD visual interface, implementation of subsidence-based horizontal strain calculations for multiple-seam situations, and pillar safety factor calculations. To demonstrate these new features, a multiple-seam case study of a longwall panel undermining an active set of main entries is presented.

Jan 1, 2006

By M. Rossi

Geologic ore controls are usually interpreted and modeled from cross sections and plans, as they are critical to construct meaningful and accurate ore reserves models. The geologic boundaries are often modeled as two-dimensional surfaces or three-dimensional solids and used as hard boundaries to constrain the grade estimates. In many cases, the geologic model is the most important factor in estimating the mineralized tonnage predicted by the reserves model, since it is generally drawn to separate the volumes of mineralized and waste material within the deposit. Because geologic models are interpreted from widely spaced drill hole data, the accuracy of the contacts of the different zones modeled could be poor. The lack of accuracy in the definition of geo-logic zones can have a significant impact on a resource model. In this paper it is shown that the geologic interpretation can and should be checked for potential biases. In particular, an unbiased overall volume of the original drill hole information with respect to the resulting solids and codes assigned to the block model is sought. In addition, geostatistical conditional simulations can be used to simulate the geologic attributes modeled, thus providing an alternative view of the geology, and a measure of the uncertainty of the geologic boundaries. The simulated geologic model provides an assessment of the impact of alternative geologic interpretations on the over-all uncertainty of the reserves model. In the case study presented here, the uncertainty of the geologic model is quantified for a difficult-to-model, high-grade copper deposit in northern Chile.

Jan 1, 2004

By G. Pan

A geostatistical approach is proposed for the design of infill drilling programs. The method is consisted of three major steps: developing geological favorability models, delineating mineralization and ore envelopes, and classifying reserves or resources. Geological modeling aims at developing favorable geological zones in which drilling is designed. Modeling mineralization and ore envelopes establishes criteria on potential blocks to be drilled. Top target blocks should be those included within ore envelopes. The framework of resource categories includes five types: probable reserves, indicated reserves, indicated resources, possible resources, and barren. Indicated reserves or resources are the top priority to be drilled for the definition of minable reserves. Possible resources may be considered as targets for further exploration. The algorithms involved in the analysis include indicator favorablity analysis, ordinary kriging, and indicator kriging. A case study presented here involves a gold deposit of Carlin type. The deposit was delineated by a sparse drilling program with 230 feet of average spacing. The infill drilling program designed by the new method suggests a significant reduction on the number of holes from a regular-grid infill drilling pattern.

Jan 1, 1995

Analysing a flotation plant?s operating performance requires accurate metallurgical sampling. Typically, the aims of performing flotation plant surveys are to establish a consistent and accurate understanding of the operation of the circuit as well as to identify potential areas for improvement. Once the data have been collected, a mass balance is required to provide a consistent set of data from which plant performance can be assessed. Mass balancing is a key skill that many metallurgists and mining industry professionals are familiar with. Mass balancing reconciles the feed and product streams throughout the plant and is sometimes used for accounting of the material entering and leaving a system (eg. JKMetAccount). However more common reasons for mass balancing are: better understanding of the flowrates within a system, assessing the quality of data obtained from sampling and surveys, and providing a key dataset for assessing and improving the performance of unit operations. Mass balancing requires practice and experience to determine if the results are reasonable. There are various software programs available to assist in the mass balancing and understanding of processing plants. This paper is focused on JKMultiBal initially developed by Gay (1993), and then later commercialized by JKTech. JKMultiBal in its current release is for balancing data in both one and two dimensions, i.e. balancing data on either sized or assay bases as well as size-by-assay. With the recent trend in flotation circuits becoming more complex, JKMultiBal has been used to gain a better understanding of the processes occurring within the circuit. This paper provides a description of the program as well as several case studies where the two-dimensional mass balancing has resulted in improvements in plant performance.

Jan 1, 2009

By M. Akser, M. Tomas

Six Sigma is a methodology that uses a structured and disciplined approach to improve process performance (higher throughput, better recovery, lower cost, shorter cycle time, etc.). Specially trained people called “black belts” lead and manage Six Sigma projects. Black belts, with assistance from their team, ensure that projects follow the DMAIC (define, measure, analyze, implement and control) process phases. Timely completion of each project, with measurable deliverables, is key to Six Sigma’s significant financial success. Implementation of Six Sigma has been growing in recent years in a wide range of industries. The heavy mineral industry, like many other industries, could benefit from what Six Sigma has to offer. Specific Six Sigma project examples are included from DuPont’s Heavy Mineral Production Plant in Florida.

Jan 1, 2005

Semisoluble salt minerals are characterized by their ionic bonding and are distinguished from soluble salt minerals by their limited solubility in water. One group of semisoluble salt minerals being considered is the alkaline earth salt minerals, including fluorite (CaF2), calcite (CaCO3) and apatite (Ca5F (PO4)3), as well as celestite (SrSO4) and barite (BaSO4). Another group of semisoluble salt minerals being considered is the rare-earth salts, which include bastnaesite ((Ce, La) CO3F), monazite (CePO4) and xenotime (YPO4). Surface chemistry features of these selected semisoluble salt minerals are discussed with respect to flotation separations. First, the surface chemistry features of alkaline earth semisoluble salt minerals are reviewed, and then the surface chemistry features of rare-earth semisoluble salt minerals are examined. The discussion includes electrokinetic behavior, wetting characteristics and collector adsorption.

By Weiran Zuo, Jinsheng Guo, Chun Yu, Jinyu Zhan, Bao Guo

High-precision prediction of the target minerals’ content in the feed and concentrate products is vitally important for the efficient beneficiation of mineral resources. Visible and near-infrared (NIR) spectroscopy provides a cost-effective way for online measurement of the mineral content in an industrial process. In this investigation, simulated specimens consisting of five different types of minerals that are present in the copper oxide ore, malachite, quartz, calcite, hematite, and chlorite were prepared with a variety of malachite contents, and the mixed specimens were analyzed by a visible-NIR spectrometer in an integral sphere mode. The reflectance spectrum is used as input and the malachite content as output to build the prediction model. The obtained data was modeled by support vector machines (SVM), and a Grey Wolf Optimization (GWO) is proposed with the goal of improving the prediction accuracy. The GWO algorithm has been applied to adaptively search for the best combination of featured values. After cyclic comparison, the optimal penalty factors c and g can be quickly and accurately selected. The experimental results show that the SVM model established by the GWO algorithm has a better fitting effect and smaller prediction error, compared with other models.

Aug 3, 2023

By Thomas D. Kaufmann

Introduction What drives the price of gold? Supply and demand, of course. But in ways far different from the forces that drive the prices of other major metals, such as steel, aluminum, and copper. Gold, in fact, is one of the few commodities where both buyers and sellers are happy when the price goes up. Current production, production costs, and variations in production have little influence on its price. Gold inventories are so tremendous that current production has small impact on the amounts available to the market at any time. Worldwide gold inventory and production The world's inventories seem to be between 78 and 98 kt (2.5 and 3 billion oz). Since biblical times, the gold miners of the world have produced about 98 kt (3 billion oz), mostly in this century. Only small amounts have been thrown away and most of it - more than 78 kt (2.5 billion oz) - remain in bullion, coins, or jewelry. About 40% is held by central banks and other governmental authorities, 30% by private individuals as bullion or coins, and about 30% as jewelry. Except for some of the jewelry and the few industrial applications, this inventory is constantly available in marketable form at a price. By comparison, gold production is indeed small. The US Bureau of Mines estimates that the world produced 1.5 kt (50 million oz) of gold in 1986. Consequently, production increased world inventories by only 2%. Variations in production have a negligible or very short-term effect on the supply and, consequently, on the markets for gold. Although South Africa mines about 40% to 50% of the world's annual production, continuing labor strife there does not seem to have ruffled gold prices. Determining gold's price Gold prices, however, do determine cutoff grades in the mines and, thus, do influence production. Nonetheless, changes in production have little impact on the inventory supply. Consequently, it has small influence on the price of gold on the market. With a fairly stable supply, price changes are driven by changes in its demand. Unlike other metals, very little of the demand for gold comes from industry. Dental, electronic, and other industrial uses for gold consume less than 46.6 t/a (1.5 million oz per year). It would be safe to assume that such uses are less than 124 t/a (4 million oz per year) for the entire world. Variations in the 124 t (4 million oz), compared to a supply of 78 kt (2.5 billion oz) of supply can have only a negligible effect. Production net of industrial uses adds perhaps 1% annually to world inventories. This could, in time, affect markets. The increase, however, is mostly absorbed by population growth - more people wanting to own gold - and by gold being put in more attractive forms, such as coins. As an ancient Lydian king discovered, minting bullion permits

Jan 9, 1987

By G. Arpa

Ventilation survey using tracer gas measurement is one of the techniques for mine ventilation design, monitoring and investigation of movement of fresh air and contaminants. However, there has been little research into using both tracer gas monitoring and numerical simulation. In this research, tracer gas technique was used for quantitative assessment of airflows through narrow vein shrinkage stopes with various opening shapes and friction factors. SF6 was used as a tracer gas to monitor airflow through three narrow vein shrinkage stopes in order to obtain diffusion concentration curves against elapsed time. The mine ventilation simulator, MIVENA Ver.6, was used to construct the entire ventilation network of the mine to monitor airflows through the stopes. The diffusion concentration curves against elapsed time were simulated with a numerical model. The result shows that the concentration-time curve is unsymmetrical and is skewed to the front of the flow direction. From the results of history-matching between the measured and the simulated curves, volume flow rates of airways and stopes were evaluated. Importantly, the tailing effect of the concentration-time curve between the measured and simulated is greatly improved by reconstructing an equivalent airflow route to represent unused mine openings, dead end drives and other open spaces. Finally, it can be concluded that openings, dead end drives and other open spaces have no relation on flow rates, but affect the airflow quality provided from the inlet portal as shown by tracer gas diffusion characteristics.

Jan 1, 2009

By Edwin B. Wilson

Over the past several years, state governments have been vigorously refurbishing old health department agencies and smoke control laws in anticipation of pending federal developments. Many states now possess a mature air pollution control administrative organization and a fairly sophisticated set of regulations on air pollution, This developing network of state control legislation and regulation is the machinery which will be called upon to implement federal standards, In order to prevent the wasted effort and resources which inevitably result from hasty action, industry should be in con- tact with local and state control agencies and be familiar with lines of communication to agency representatives. Thorough knowledge of applicable laws and regulations, both current and pending, is required. Moreover, federal law and future federal air pollution control plans, should be well known. Industrial air pollution control should be geared to a long range plan which utilizes existing technology while at the same the recognizing that today's technology will be improved upon with time, Regulation, too, can be expected to become more stringent. The implications of air pollution control in the Appalachian region of the United States will be felt most strongly by the coal industry of this area. Either directly or indirectly most regulations in these states have a significant bearing on coal mining, processing, utilization or waste disposal. The extent of coal-related activity in the Appalachian States of West Virginia, Pennsylvania, Maryland, Virginia, Kentucky, and Tennessee can be observed from the data provided in Table I. This data indicates that 86 percent of active bituminous coal mines and 69 percent of bituminous coal production were accounted for by these states. The purpose of this paper is to provide information on current and proposed legislation and regulations on air pollution in the Appalachian states, The information should prove valuable not only to the coal industry but also to industry in general as a means of evaluating both pollution control action that has been taken to date and the course of future control measures. Reference information in the forms of addresses of appropriate agencies and citations to specific state laws and regulations is provided. All information is current as of February, 1969.

Jan 1, 1969

By Colin Rawlings, Simon Pepper, Maria Karakitsiou, John Mathews, Peter Townsend, Russell Bowler, David Keeble, Christopher Darton, Scott Sadler

National Grid needs to maintain a connection between two existing electricity sub-stations (Beddington & Rowdown) in the Croydon (south London) area, and allow the replacement of two 275 kV cable circuits that are buried under roads. This is to be achieved using a single 400 kV cable circuit within a 10 km (6.25 mile) long, 3 m (9.8 ft) diameter high voltage cable tunnel which is being driven through water bearing Chalk, at depths ranging from 5 m (15 ft) to 80 m (262 ft), with four access shafts(12.5 m (41 ft) in diameter) ranging in depth from 10 m (31 ft) to 40 m (131 ft). The Chalk in this area acts as a source of public drinking water supply (PWS) and is protected by areas designated Groundwater Source Protection Zones. To minimise the groundwater risk the design and construction of the cable tunnel and shafts has paid particular attention to the construction materials used, including testing of these construction materials prior to use, developing construction methods (including the design of the Earth Pressure Balance TBM) and maintaining a groundwater monitoring & testing programme prior to and during construction to ensure the integrity of the Chalk aquifer is maintained as a drinking water source. This paper describes the tunnel &shaft design and construction in relation to these particular groundwater environmental issues which set new precedents for tunnel assessment, design and construction requirements in the United Kingdom.

Jan 1, 2007

By J. Wickens

This paper discusses how Bald Mountain Mine dramatically reduced mercury production by treating process solutions with a liquid reagent called UNR 811A. The reagent is marketed by Cherokee Chemical Co., Inc. A summary of the bench tests comparing several different reagents is given. The ensuing plant trial is discussed and results are presented. The plant trial treatment costs are discussed. Finally, potential cost savings are discussed.

Jan 1, 2001

Bortech’s BoreClad corrosion protection system will be displayed at MINExpo. BoreClad is an innovative system for inside diameter cladding of nozzles, tubes and other circumferential devices. Pressure vessels, mud pumps and other mining equipment must be protected from corrosive caustic chemicals. Usually manufactured from mild steel, they can be clad with a protective material, such as stainless steel, to provide corrosion resistance. However, most welding processes leave voids where corrosion can damage the base metal. BoreClad provides void-free welds by combining gas metal arc welding with automated feed and rotation of chuckable parts. Workpieces of up to 915-mm- (36-in.-) long with a 460-mm- (18-in.-)swing can be clad with stainless steel, Iconel or other exotic metals. In addition to eliminating the voids associated with hand welds, BoreCladcan lay more than 2.2 kg/h (5 lbs/hour) of metal. That is a significant reduction in weld time. Web sitewww.bortech.com.

Jan 1, 2004

By S. Shi, J. Y. Hwang, B. Li

Silver, copper, and zinc are commonly known elements with antibacterial and antifungal capabilities. Attempts have been made to dope silver on minerals, glass, and ceramics and the resulting materials have been investigated for their antibacterial and antifungal properties. Since silver is expensive and very reactive, silver doped materials have been found inappropriate in some applications. Copper-vermiculite is investigated as an alternative. Vermiculite has high cation exchange capacity on the magnesium ion in the crystal structure. Copper ion may have a high tendency to replace magnesium because of similar charge interference and ionic radius. Copper-vermiculite is prepared by reacting vermiculite and copper chloride solution. By impregnating copper ions into the nanometer openings between the layers of vermiculite, it is possible to render the composite with antibacterial functions if the copper ions could be released gradually from the composite. The antibacterial efficiency of Cu-vermiculite against Escherichia coli was studied using the Halo method. The results show that Cu-vermiculite is effective for preventing the reproduction of the bacteria. Heat treatment of Cu-vermiculite at up to 400°C does not show significant changes in antibacterial activities.

Jan 1, 2002

By B. W. Cavender

Capital investments are made for a variety of reasons, ranging from providing incremental capacity at existing operations to developing and implementing new technologies intended to radically improve a company's capabilities. These projects generate very different business opportunities and create value in distinctive ways. For incremental improvements, the capital budgeting process assures at least a loose fit between short-term goals and readily available resources. However, the criteria used to evaluate capital projects often prevent a company from committing to more aggressive goals, which lie beyond the firm's current abilities or resources. Such projects may not have clearly identifiable future cash flows, and the degree of interaction with other projects and the nature of the risk incurred may be difficult to estimate. Additionally, by focusing only on quantifiable benefits, the budgeting process often fails to recognize "soft" improvements such as increased operating flexibility or new knowledge generated by such projects. By rejecting these projects, the capital budgeting process may actually harm the company's future competitive position.

Jan 1, 1999

By Serge Moalli

The Ashlu Creek Hydro-electric project, located north of Squamish, BC, at the confluence of Ashlu Creek and the Squamish River, comprises a 49 MW run-of-river project and features a 4.08 m diameter, 4.4 km power tunnel and a 128 m deep drop shaft. The Ashlu Creek Hydro-electric project is being developed by Innergex under Ashlu Creek Investments Limited. Site civil works are being completed by Ledcor CMI of Vancouver with tunnel construction by Frontier Kemper Constructors ULC under a lump sum design-build contract. Site works got underway in September 2006 with the construction of the tunnel portal and laydown area. These site works required rock slope stabilization over a 50 m rock slope to secure the laydown area as well as the construction of a tail track muck tipping station and structural wall to facilitate TBM excavation and spoil removal. Starter tunnel construction commenced in early 2007 and TBM tunneling started in the late spring of 2007 and is planned to continue until early 2009. The power tunnel is being excavated using a 1,200 kW Wirth open-type hard rock TBM dressed with 31?17' cutters. The TBM featured two fixed mounted rock bolt drills behind the finger shield: these were removed and replaced with jacklegs to improve access. A probe drill at the end of the main beam is also present. The geology along the 4.4 km power tunnel comprises very strong and generally massive granitic bedrock with rock strength greater than 225 MPa. A unique feature of the project is that no subsurface investigations have been completed for the tunnel however extensive bedrock outcrops are present along the Ashlu Creek valley. A historical quarry exists approximately mid-way along the tunnel alignment that has exposed good quality granitic bedrock. TBM tunneling to date has achieved advance rates of 10?20 m/day with a maximum of 23 m and has encountered all of the anticipated six major fault zones where the installation of various standard high capacity tunnel support was successful to facilitate TBM advance through these sections.