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By K. Burke, K. L. Myers, R. Espell

Barrick Goldstrike’s (Goldstrike) AA Heap Leach Pad is an HDPE lined facility used for gold recovery from low grade ores using conventional cyanide heap leach technology, operated from 1987 through 1999. Goldstrike prepared a unique reclamation plan for the AA Leach Pad Facility to provide for a cost-effective, environmentally sound facility closure and to fulfill the State of Nevada’s closure requirements. Traditional Nevada leach pad closure has involved rinsing to reduce cyanide concentration to an acceptable level, followed by reclamation. However, certain metals and compounds are not typically reduced by rinsing and some constituents may increase in concentration with rinsing. A closure scenario to effect limited infiltration through installation of a capillary cover for the leach pad was developed. The capillary cover was constructed by placing a fine-grained layer above the coarse-grained spent leach material to create a capillary break. In an arid climate such as Nevada, the fine-grained layer will rarely reach full saturation and the cover will be able to store water during precipitation and allow removal of water through evaporation and transpiration (ET) during the growing season. A 1.22 m (4 ft) cover thickness was selected as the optimum design cover thickness. The drainage network on the surface of the re-contoured AA Heap Leach Pad was specifically designed to enhance the revegetation, reclamation, and sediment yield control aspects of the AA Heap Leach Pad closure, while resulting in a natural looking surface, compatible with the surrounding topography. Adjacent natural topographic features were used to establish target design parameters for re-contouring and erosion control design.

Jan 1, 2001

By M. Pawlik

The rheological properties of mineral suspensions affect the design and operation of transport, mixing, size classification, grinding, gravity concentration, flotation and de-watering systems. In many cases, the rheological properties can be modified to improve processing through the addition of chemical additives. These additives may be either organic or inorganic and generally affect the state of particle aggregation or dispersion. Inorganic modifiers act primarily by affecting the surface charge of mineral particles and thus control the magnitude of electrostatic attraction/repulsion between particles. The action of organic additives (polymers and surfactants) is a combination of electrostatic and steric forces – the latter being related to the molecular weight of these reagents. While low molecular weight polymers are dispersants (viscosity reducers), high molecular weight polymers are likely to induce flocculation and increase yield stress.

Jan 1, 2004

By Reginald Dias

Mining operations take a tremendous toll on equipment, operating in difficult conditions day after day. Owners and operators cannot make the job any easier, but they can give their equipment an advantage. Equipment life may be extended through preventive maintenance and the proper application of quality lubricants. This means lubricants that are made to last longer and stand up better to the punishment mining equipment must endure. There are several practices to consider as part of a successful preventive maintenance program. A good place to start is to review original equipment manufacturer recommendations about servicing and maintenance intervals for each part of the equipment, especially the engine. If these recommendations have not been followed, owners and operators must begin periodic service work on equipment to help minimize equipment down-time and extend engine life.

Jan 1, 2003

By M. T. Ityokumbul

The use of yield index, the product of the yield and gangue rejection, for the optimization of separation processes is presented. The characteristics of the yield index are contrasted with separation efficiency calculations and applied to laboratory froth flotation and washability data. Data from continuous froth flotation tests conducted to "optimize" froth flotation using process optimization software were also evaluated with the yield index procedure.

Jan 1, 1997

By William R. Yernberg

The Society of Economic Geologists (SEG) held its biennial conference May 14 through 16, 2006, in Keystone, CO. SEG is an international organization with about 3,500 individual members with interests in economic geology. The 2006 SEG conference theme was “Wealth creation in the minerals industry — integrating science, business and education.” The conference exceeded expectations with 705 participants, including 102 students, from 44 countries. The conference featured 30 oral presentations, 24 professional posters and more than 70 student posters. The conference also included a trade show with 50 vendors, numerous field trips, workshops and social activities.

Jan 1, 2006

By Jack Parker

Critical width Before we go further into pillar design, we should look into the matter of "critical width," because of its effect on pillar behavior. Critical width refers to the greatest width that the rocks above the mine can span before failure or, if there are pillars, the width to which we must mine before the pillars accept the full weight of the overlying materials. There are theories to help calculate that probable width, and they usually boil down to one-quarter or one-third of the depth of cover; but they don't always fit, and it would be better for us to understand the factors that control local conditions. Critical width may be controlled by the thickness or strength of one or more of the strata above the mining horizon. In a gold mine, we might have a thick granite or basalt above us, perhaps capable of bridging across most or even all of a small ore body. In that case, pillars might have to support nothing, or perhaps just the weaker or damaged rock below the strong main roof. Obviously it would be wrong to design for tributary load on pillars based on some lab-determined rock strength. In some coal mining districts in Utah, huge steps can be seen in the mountain sides, with slopes on weathered shales and vertical cliffs 100 or 200 ft high in thick, hard sandstones. The sandstones are capable of bridging across hundreds of feet, often making mining deceptively easy at first, but it becomes more difficult as greater areas are opened. Sometimes such a mining sequence leads to violent bumps and bursts as the wide spans of sandstone sag and bear down on the working faces, like giant nutcrackers, or as bridges eventually fail, releasing much pent-up energy.

Jan 1, 1993

By Bernie W. Martin, Raymond Leray, Christian Criado

Aguas Argentinas,1 a consortium managed by Lyonnaise des Eaux of France and operator of the world’s biggest privatized water supply and waste water collection system for the City of Buenos Aires, a city of 9 million people, was faced with the daunting task of providing new service to 1.6 million more people in the first five years of their 30 year concession. Aguas Argentinas elected to use the Negotiated Compressed Process - NCP - for the fast track implementation of a 15000 meter, 3,5 meter diameter tunnel, a key component of the infrastructure master plan. NCP was developed by Klohn Crippen for the $200 million international railway tunnel between Canada and the United States. The conceptual design of the project was performed by Safege Montgomery-Watson, who engaged Klohn Crippento assist with the NCP, the preparation of the tender documents, and implementation of theproject during construction. The process included the purchase by the client Aguas Argentinas of two sophisticated 4 metre diameter earth pressure balance tunnel boring machines from Herrenknecht of Germany. Construction of the tunnel is being performed by the consortium Wayss & Freytag (Germany) and Sollazzo Hnos S.A. (Argentina). The water tunnel is being built with a one pass, bolted segmented gasketed reinforced concrete liner. The purpose of this paper is to describe a transferable methodology for this innovative contracting procedure, the project organization and quality control plan for this important world class tunnel project which is designed to service one of Latin America’s largest metropolitan areas.

Jan 1, 1997

By Albert Hofstra, Joel Leventhal

The gray, dark gray and black colors of the sediments and the presence of pyrite in the Carlin, Jerritt Canyon, Horse Canyon, Betze, and Gold Acres sediment-hosted disseminated gold (SHDG) deposits indicate that these rocks are not oxidized with respect to carbon and iron sulfide. Both ore and non-ore host rocks generally are dark colored. Analyses for noncarbonate carbon (usually called organic carbon) in samples from SHDG deposits and related unmineralized rocks indicate that these rocks contain from a few tenths to a few percent carbon. We use the term noncarbonate carbon because, strictly speaking, organic carbon denotes carbon that is bound to hydrogen. However, the carbon present in SHDG deposits and related rocks has very little hydrogen chemically bound to it. Rocks with less than 2% organic carbon are usually gray in color. The dark colors in our samples are due to the relatively high temperatures that these rocks have experienced relative to organic matter maturation. We confirm the results of Nelson et al. (1982) that previous reports (for example, Radtke and Scheiner, 1970) were incorrect in reporting significant amounts of humic acids, extractable hydrocarbons (bitumen) or "carbonaceous" material. We believe these reports had problems with contamination or misdirected emphasis. Our samples consisted of unweathered rocks, collected mainly from mine cuts (benches, trenches, cores) and put into glass containers or wrapped in aluminum foil to avoid contamination. Only a few samples were collected from natural outcrops. We were careful to avoid samples in proximity to blast holes that were packed with ammonium nitrate and diesel fuel ("ANFO"). Contamination by ANFO may explain some of the previous reports of hydrocarbons, pyrobitumens, humic acids and anomalous nitrogen. When we were collecting samples, it was apparent that in addition to lithologic and color differences, the surface appearance of the rocks was distinguishable: "preg robbing" material that had a sooty surface; "graphitic" rock with a shiny surface; and more ordinary rocks that had a flat gray or black appearance. [Preg robbing is a term for ores that adsorb gold from the milling circuit; the graphitic material had not been x-rayed to actually identify graphite.] We hoped that laboratory study of these samples would show some fundamental differences that we could relate to ore genesis. Even though these sample types appeared different in the field, we could not distinguish any differences in thermal maturity (see below). Normal petroleum/organic geochemical laboratory procedures (solvent extraction, Rock-eval, pyrolysis-gas chromatography) failed to yield much information because the carbon was over-mature relative to oil and gas generation. Rock-eval results show less than 20 (± 20) mg of pyrolizable hydrocarbons per gram organic carbon (and an indeterminate Tmax) indicating that the organic matter in these deposits is burned-out relative to petroleum generation [with an H/C (atomic) ratio of less than 0.41. Because of the non-definitive results from standard organic geochemical methods, x-ray diffraction (XRD) and Raman spectroscopy were used to characterize the carbon. Prior to XRD, samples were treated with HCl and HF acids (1) to remove quartz that has a peak near 26° [20] at the position of the 002 peak of graphite and (2) to concentrate the carbon to a level detectable by XRD. The residue was put on a colodion mount and analyzed by XRD. The XRD analyses yielded a broad peak at 26° [20]. The shape of this peak indicates that the carbon is more thermally mature than anthracite rank coal but less mature than crystallized graphite. Based on XRD results from the literature (Landis, 1971) that are calibrated to metamorphic facies, results from our samples correspond to pumpellyite-actinolite to lowermost greenschist facies conditions, probably

Jan 1, 1990

By Amin Mousavi, Soroush Khazaei, Yashar Pourrhimian

As a factory-like method, sublevel caving consists of development activities, stockpiling and production activities that are carried out on different levels independently. Therefore, considering the operation from the development phase to the plant will lead to more reliable production scheduling. This paper presents a mixed integer linear programming framework for the long-term production scheduling of sublevel caving that maximizes the net present value while satisfying development activities, mining, and processing capacities, continuous mining, the allowable number of active mining units, grade blending, and vertical and horizontal sequencing. The model is coded in Jupyter Notebook and is solved using the CPLEX solver.

Jun 25, 2023

By Chee S. Theng

As the 2018 president of the Society for Mining, Metallurgy & Exploration Inc., I am pleased to present the 2018 issue of the Transactions of the Society for Mining, Metallurgy & Exploration Inc., Vol. 344. A significant portion of the contribution that we make as a professional society is the publication of professional and technical papers that accelerate the advancement of scientific knowledge and enable the transfer of technology. Communication within the mining community is the key to a successful society. This technology exchange continues a tradition that dates back to the 1871 meeting of 22 mining engineers in Wilkes-Barre, PA, that resulted in the founding of the American Institute of Mining, Metallurgical and Petroleum Engineers (AIME). Those individuals envisioned that these transaction volumes “would form a most valuable and greatly needed addition to our professional literature.” This volume fulfills that pledge. The 2018 Transactions consists of a total of 59 technical papers, encompassing all 25 papers published in 2018 in the Technical Papers Section of Mining Engineering (Vol. 70) and all 26 papers published in 2018 in Minerals & Metallurgical Processing (Vol. 35). Additionally, this volume contains 8 papers that are being published for the first time in this issue. The papers presented in this volume were written by some of the most distinguished professionals in the industry worldwide. All of the technical papers were peer-reviewed. The process of review and publication requires much hard work by authors, reviewers and our Publications staff. As the 2018 president of SME and on behalf of all our members, I would like to extend our gratitude to all whose volunteer efforts contributed to the publication of this volume. The new year brings an exciting change. The publication of Transactions will cease with this volume. Instead, our Minerals & Metallurgical Processing journal has the new name of Mining, Metallurgy & Exploration (MME), and Transactions as well as the Technical Papers Section of Mining Engineering are incorporated into MME. The journal is published in partnership with Springer Nature, and all SME members have free electronic access to the journal.

Jan 1, 2018

By E. V. Manlapig

This review paper describes recent advances that have been made at the Julius Kruttschnitt Mineral Research Centre (JKMRC) in Brisbane in developing a framework for simulating the flotation process. The work has been carried out collaboratively with the Mineral Processing Research Unit of the University of Cape Town in South Africa (UCT), as part of the Australian Minerals Industries Research Association (AMIRA) P9 Project. The framework consists of four components, namely – the mathematical model of the flotation process, suitable measurement tools for characterising the flotation cell, a computer program for modelling and simulating the process and the plantas for testing and validating the flotation models. A brief description of the model is first presented, then a number of applications of the model are described. The paper shows how the model can be used to optimise the performance of flotation cells, and then two case studies on the modelling methodologies are described. Finally the current and future plans of the project are outlined.

Jan 1, 2001

By William G. Doepken

With most of the mining industry emerging from the deepest business recession in 50 years, primary attention must be given to surviving in a business climate where dominant foreign competition, depressed prices, and potential overcapacity hang heavy over much of the industry. While already shackled with regulatory constraints, restrictive work rules, and high labor costs, mine operators are faced with the difficult task of reducing costs and improving productivity while operating at less than full capacity. To counter these nearly over-whelming factors, the mining industry must continue at the national level to seek regulatory relief and a rational policy toward foreign competition from government-controlled mines. In addition, dialogue with labor organizations must continue to minimize the impact of labor costs, cost escalators, and antiquated work practices. Although national and international actions have a tremendous impact on the future of domestic mining operations, local actions by mine operators to dramatically improve mining productivity will strengthen the industry's competitive stance. Before any substantial progress can be made, however, mine operators must recognize and define areas that depress productivity and establish goals and measures for improvement. Once problem areas are defined, a combination of technological and motivational concepts can be applied to improve productivity. Timing of Improvements While there is an immediate need for productivity improvements, only certain concepts offer near-term improvement potential while others must, of necessity, fit into a mid-range or long-range time frame. Near-term solutions (immediate to one year) likely will involve motivational concepts - work incentives and training - coupled with available technological concepts that require little capitalized development or site testing. Mid-range solutions (one to three years), by contrast, will include technological improvements in mining equipment, techniques, and systems automation. These concepts require a longer period of capitalized development and site testing before use. Long-range solutions (three years or more), which include adoption of new mining methods and computerized control systems, will appear only after prolonged research and capitalized development programs. Motivational Improvements Developing motivational con-

Jan 11, 1983

By Jason Morrison

The Norwegian Lake Tap Method was successfully used to tap into the side of Lake Dorothy 36.5 m (120') below the lake surface. The lake tap allows water to flowinto an access tunnel from the lake lowering the water elevation below its natural out-fall. When the lake reaches a predetermined elevation below the outfall, a 1.5 m (60?) valve in the tunnel will be shut and discharge from Lake Dorothy will stop temporarily allowing construction of a dam located 2.9 km (1.8 miles) downstream at Bart Lake. The lake tap and tunnel were one phase of the $64 million Lake Dorothy Hydroelectric Project, owned and operated by Alaska Electric Light & Power Company (AEL&P), a private utility located in Juneau, AK. The Lake Dorothy portal site and tunnel are located approximately 25.7 km (16 miles) southeast of Juneau, AK, in the remote Tongass National Forest at an elevation of 701 m (2,300') above sea level in the mountains above the Taku Inlet. Thirty degree snow covered mountainsides and limited access by helicopter were just two of the many factors which challenged this unique project. The lake tap and tunnel development consisted of 250 m (820') of horizontal tun-nel, averaging 3.6 m x 3.6 m (12' × 12'), excavated using conventional drill and blast methods in highly competent Granodiorite and Tonalite rock, placement of one 3.9 m (13') long concrete plug, or bulkhead, located at the tunnel midpoint, and one 3 m (10') diameter lake tap into the side of Lake Dorothy. This paper will provide an analysis of the logistical and engineering challenges involved in the development of one of only a handful of lake taps in North America. AEL&P and contractor J. S. Redpath Corporation worked together to complete this critical project phase safely and on schedule, in a location accessible only by helicopter and plagued by constantly changing, harsh weather conditions. A strict schedule had to be maintained to ensure the timely operation of the downstream dam and power plant.

By Anna Gustafson, Sohail Manzoor, Håkan Schunnesson

Sublevel caving operation relies on the estimation of ore grade at drawpoints, as the mine management uses grade to decide whether the material at a certain ring should be loaded or abandoned. Grade is estimated in various ways, including visual estimation, density-based calculation, and sampling and assay methods. The grade estimation at the world’s two largest underground iron ore mines owned by LKAB in northern Sweden is based on the density difference between ore and waste. The calculations assume a constant swell factor, a theoretical fill of 100%, and a linear relationship between bucket weight and material grade. This study evaluated these assumptions in detail based on the loading data for 12,237 buckets and concluded that the method has some shortcomings which render the assumptions invalid. Further research is required to deal with these shortcomings to improve estimation of the material grade.

Oct 17, 2022

By Daniel B. Brimhall

The research presented here was initiated to investigate the role of atmospheric oxygen in the leaching of copper waste dumps. The problem of increasing the recovery rate of copper from these dumps is or great importance considering there are by conservative estimate in excess of fifteen billion pounds of copper located in dumps in the western United States. At this time, there is an increased interest in recovering copper from these dumps on a large scale. Large tonnages of low-grade material are being placed on the waste dumps of most copper mining operations in the western United States each day. The size of these dumps ranges from 5.5 million tons at Mineral Park, Arizona, to 4 billion tons at Kennecott's Utah operation (1). Leach solutions are recycled and contain ferrous and ferric sulfates. Large quantities of dissolved aluminum, magnesium and calcium salts may also be present. To this solution make up water is added to maintain the solution inventory and sulfuric acid is added for pH adjustment. Iron is introduced into the leach solution by the dissolution of the iron-containing sulfide and oxidized minerals present in the ore deposit. In addition to the iron from dump leaching, iron is also introduced during the precipitation process when the pregnant solution is passed over metallic scrap iron if cementation is used to reduce the copper in solution.

Jan 1, 1972

By R. Graeme, J. Komadina

Gold Fields acquired an option to purchase the Cerro Corona Project, located in Hualgayoc, Cajamarca Department, Perú, in December 2003. In January 2006, the option was taken up and the transaction closed. During the intervening months, Project development occurred against the backdrop of a Presidential election, increasing national social activism and environmental regulation, rapidly escalating operating and capital costs, as well as unprecedented demand for engineering and technical skills. Project “Lessons Learned” are outlined and discussed in the context of an evolving strategy.

Jan 1, 2007

"The Ohio River Bridge East End Crossing Tunnel requires a 75-year service life of its cast-in-place reinforced concrete lining. This twin-tube 3-lane (each tube) highway tunnel is about 55-ft wide and 30-ft high. Since unified tunnel service life prediction methodology does not exist in the US, challenges occurred during the design-build phase of this project. These challenges include the methodologies in determining the reinforced concrete’s degradation mode, the lining’s surface chloride concentration level, the reinforcing steel’s critical chloride threshold value for corrosion, how to verify the concrete’s diffusion coefficient, and the durability impact from concrete crack width. This paper presents a methodology in verifying the proposed concrete mix can achieve the service life requirements. This methodology can be adopted for service life prediction for future tunnels to be built in the US. INTRODUCTION The Ohio River Bridge East End Crossing (ORBEE) Tunnel is part of a Public Private Partnership project, which connects transportation network between Louisville, Kentucky and southern Indiana. Located in Louisville, Kentucky, the twin-tube highway tunnel provides northbound and southbound lanes of the Kentucky approach to a new bridge across the Ohio River. Tunnel lengths are approximately 1,675-ft and 1,685 for the northbound tube and the southbound tube, respectively. Connected by two cross-passages, both tubes have a roadway width of 40-ft, for 3-lane traffic, and a vertical clearance of 26.5-ft.The tunnel was constructed by drill and blast method with shotcrete and rock dowels as initial ground supports. The final tunnel lining system includes: •,Nominal 16” cast-in-place reinforced concrete lining, with 2” and 3” concrete covers over reinforcing steel for its extrados and intrados, respectively. •,20” cast-in-place reinforced concrete invert slab, with 4” and 3” concrete covers over reinforcing steel on its top face and bottom face, respectively. •,PVC waterproofing system around tunnel perimeter, excluding invert slab. •,Perforated PVC groundwater collection pipes on both sides of the tubes and one below the invert slab of each tube."

Jan 1, 2016

By R. P. Proulx

The Meikle Mine is a high grade, underground goldmine utilizing primary-secondary longhole open stoping with delayed backfill to produce 2700 tpd(3000 stpd) of ore. Hot and reactive ground conditions were encountered early on in the mine life. Ground temperatures up to 166°C (330°F) were measured. In the early stages of mining, the mine experienced premature detonations using different explosive products. The learning curve to safely mine this high-grade gold deposit in hot and severely reactive ground was indeed very steep. Currently, the Meikle Mine uses a special buffered bulk emulsion in all blasts to address hot and reactive ground concerns. In addition, exacting procedures are also followed to ensure safe work with explosives. The combination of new explosives technology and strict loading procedures permits high mine productivity with the highest degree of safety.

Jan 1, 2000

By H. H. Murray

Clay minerals are one of the more important industrial minerals. They are used in many products and because of different specifications may require special processing which can be either wet or dry. The clays discussed are bentonites, kaolins including ball clays, and palygorskite (attapulgite). In order to design a process flow sheet for these clay minerals, the physical, chemical, mineralogical, and optical properties need to be evaluated. Each species of clay minerals require a group of special tests which are described in this paper.

Jan 1, 2009

By F. G. Rinker

The world demand for metallized iron continues to increase, keeping pace with steelmaking requirements for lower cost hot metal. Virgin iron ore and in-plant oxide fines can be reduced to direct reduced iron (DRI) and hot briquetted iron (RBI). MR&E has developed an improved coal-based process for cost-effective production of either DRI or HBI. Starting with dry compaction, the process combines the latest technology for material preparation, rotary hearth furnace construction and environmental control. Coarse iron ore fines are blended with pulverized non-metallurgical coal to produce a highly metallized (>90%) product. This paper presents production and installation cost data based on operating and under-construction iron oxide reduction facilities.

Jan 1, 1999