Search Documents

Compagnie Miniere Esperance (CME), a mining company based in French Guyana, operates a gold primary ore body in open pit. The ore is processed through crushing, grinding and gravity separation. Tailings are stored in a ?fine? pond. Analyses of the fine ponds proved a residual gold grade sufficient for a chemical treatment. However, direct cyanidation would require a too large installation, regarding the local conditions (accessibility, supplying and rainforest meteorological conditions). It has been then decided to test the feasibility of a pre-concentration using flotation. Lab tests have been carried out by SGS Lakefield (Canada) in March 2007, which proves the technical feasibility. Therefore, CME asked Caspeo to: ? Carry out an on-site flotation pilot campaign. ? Design an industrial flotation circuit. The tailings reprocessing will contribute to a better tailings management and a dry up of the gold resource, limiting the risk of illegal mining after remediation of the CME site. CME MINE The Esperance gold mine is located in French Guyana, in the vicinity of several gold deposits as Omaï, Rosebel or Camp Caïman, holded by Iamgold and Newmont. These main gold deposits are located on the figure 1. Esperance was put into operation in the early 90?s. The first years were devoted to the mining of alluvial gold in the gravel of the Esperance Creek. Since then, operation was led in the primary gold deposit. Annual production is on average 254kg for a total production in fifteen years of 4300kg. Geology Esperance deposit is located in the greenstone belt of the Guyana Shield. Mineralization is in tectonic contact between sedimentary basin of Maroni and a granitic massif. Clastic series, composed of conglomerate and lamina sandstone, overlie a volcano-sedimentary basement (series called "Paramaca"). The area is strongly folded by shear movements, resulting from granite deposit. Gold is in interlacing quartz veins intersecting the clastic series. Gold is present in association with pyrite. Other elements, as silver or arsenic, are in negligible quantity. Exploitation The Maroni River is the only access to the Esperance mine. Only the saprolite and a part of the transition rock are extracted in the open pit. Excavation works are done using shovels Hyundai 450 (4 units) and haulage works using articulated dumpers Terex TA35 (4 units). These two sorts of equipments are presented figure 2. Mill The mill is composed of crushing and grinding processing plants. After gravity concentration, both plants produce tailings that are stored in two ponds: the first pond contains coarse product which segregates the particles crushed to 2mm upstream and settled clays downstream; the second pond contains the fine product made of particles ground to 200µm. These two ponds, bordered by dams and diversion canals, are located on former alluvial sites of Esperance Creek (see figure 3). [ ] The CME mill is currently producing gold concentrate, with a global recovery of about 67%. The ore is crushed by one jaw crusher and two hammer crushers. The ore then passes through a Knelson KC 48 gravity concentrator, producing a first gold concentrate. The

Jan 1, 2009

Recent U.S. mine disasters identified a need for improved training of miners in escape from mine fires and explosions. Researchers at the National Institute for Occupational Safety and Health?s (NIOSH) Spokane Research Laboratory (SRL) have designed fire-escape training software for use in a mine-safety training course. The software allows four trainees to work together in a virtual world via a computer network. Trainees responded favorably and showed a marked improvement in locating the proper evacuation routes on subsequent trials. In collaboration with the Pittsburgh Research Laboratory (PRL), a more elaborate fire evacuation scenario is being developed. Further study is needed to confirm that virtual training will translate to improved safety outcomes in the real world. Keywords: virtual reality (VR), safety, training, mining, mine fire evacuation

Jan 1, 2009

By Harvey W. Parker

Our industry has developed to the skilled, experienced and productive industry that we now enjoy as a result of the visions of great engineers throughout history, but, in particular for their visions in the last 1 centuries. Unfortunately for our forefathers, the technology lagged so far behind that these exceptional visions could not be realized for decades, sometimes for a century. All that has changed in recent time and many bold and visionary projects can now be constructed and operated because of dramatic advances in technology. Before, say, 1950, tunnel technology developed very slowly. However, technology is now developing at such a fast rate that planners and decision makers are challenged to stay ahead. Moreover, new technology will develop during the lifetime of any project that can dramatically improve under-ground space projects. One of the best examples of this technological advancement is that of closed-face TBMs which now make tunneling feasible in previously impossible ground conditions. Since it usually takes a decade or more to plan, overcome environmental and political issues, construct, and put into service major projects, planners and designers are challenged by the changes in technology that occurs during the long time span of planning and construction. This is particularly true of large infrastructure projects such as transportation, water and wastewater systems and other major underground schemes. Also, since the serviceable life of many of these tunnels is often over one century, planners must consider not only lessons learned from the past but also what new concepts and innovations may develop over an extremely long time. These and other issues create a great challenge to planners and illustrate the great importance of careful but creative vision and flexibility during planning of long-term tunnel and underground space projects.

Jan 1, 2008

By A. Zeni, S. L. Bessinger, T. A. Palm

San Juan Coal Company (SJCC) operates an underground coal mine near Farmington, New Mexico. Continuous miners and a longwall produce 7-8 million tons per year. The coal seam at SJCC has tested to have a propensity for spontaneous combustion. As such, during feasibility for this project, it was elected to utilize a bleederless ventilation system on the longwall. Three-entry gateroads are developed, and the longwall gob is sealed as mining progresses. SJCC utilizes a nitrogen injection system to continuously inertize the gob. In 2004, the mine was nearing completion of its first longwall district. The next district would contain longer panels (up to 12,500 feet). Due to the liberation of methane, and to a lesser extent hydrogen sulfide, a typical wrap-around ventilation system would not be appropriate. Not only would gas concentrations likely be challenging, but the overall ventilating pressure in the mine would have to be increased beyond limits established to mitigate the potential for spontaneous combustion. Given the above-described operating constraints, SJCC determined a need for a small ventilation shaft in the back (longwall setup area) of the next district that would draw adequate air past the longwall seals to maintain low gas levels and permit the required regulatory inspections to occur. Extensive ventilation modeling and gas desorption testing indicated that the shaft would be required to handle a volume of air ranging from 40,000 cfm to as high as 185,000 cfm. This large range is driven by the position of the longwall face with respect to the shaft and the effectiveness of the SJCC degasification program (SJCC uses vertical gob vent boreholes and horizontal in-seam methods). Ventilation simulations determined an appropriate diameter for the 350-ft-deep shaft to be 5 feet. Having determined shaft size, the next decision related to the method of shaft construction. Conventional shaft sinking was ruled out, due to the small diameter. Raise boring was an attractive option but had two drawbacks: (1) development crews would reach the bottom of the shaft just a few weeks before longwall startup, leaving a compressed timeframe to install the shaft, and (2) raiseboring requires additional underground entries to be developed to stow the project’s cuttings. While raiseboring remained a viable option, the problems associated with it led SJCC to also investigate blind drilling.

Jan 1, 2006

By A. B. Cecala

Enclosed cabs have been used for many years to isolate workers on mobile equipment in the mining industry for health and safety reasons. These enclosed cabs create a microenvironment for workers where they can be either more protected or more vulnerable to contaminants. Over the past decade, the National Institute for Occupational Safety and Health (NIOSH) has performed substantial research efforts to improve the air quality inside enclosed cabs of both underground and surface mobile mining equipment. In these efforts, NIOSH has partnered with mining companies, original equipment manufacturers (OEMs), and manufacturers of filtrations and pressurizations systems in a synergistic effort to reduce respirable dust and improve the air quality inside these enclosed cabs. Various field studies over this time have shown an array of results ranging from very minor to very significant reductions (protection factor: 3 ? 89) in respirable dust levels inside these enclosed cabs. In addition to and concurrent to the field work, NIOSH also performed a comprehensive laboratory study to evaluate all the factors involved in cab filtration and pressurization systems and identified those factors that were most significant for an effective system. From this comprehensive research effort, the key components for an effective filtration and pressurization system have been identified in an effort to provide the best air quality, thus minimizing the respirable dust exposure, to equipment operators inside of enclosed cabs of mobile mining equipment.

Feb 27, 2013

By Bruce Gellar

For the past six years, the author has made it a priority to attend the Prospectors and Developers Association of Canada’s (PDAC) annual conference. This most recent meeting took place March 10-13, 2002in Toronto, Ontario. In the three years since the author’s last PDAC report, the mining industry has undergone a severe trough. Some the industry’s woes included deeply discounted commodity prices, rampant layoffs, mergers, and overall avoidance by the investment community. However, at each of the PDAC conferences, the author has felt a heightened sense of excitement about the mining industry, more so than at other similar gatherings.

Jan 1, 2002

By D. P. Tao, J. G. Groppo, R. Killmeyer, W. W. Wen, B. K. Parekh

Economical dewatering of ultra-fine (minus 74 m) clean coal slurry produced in column flotation to a 20 percent or lower moisture level will be an important step in successful implementation of the advanced fine coal cleaning processes. The main objective of the present study was to evaluate efficiency and effectiveness of three dewatering techniques, namely, hyperbaric, vacuum and screen bowl centrifuge, in dewatering of ultra-fine (D50 ~ 25 m) clean coal slurry produced by the `Ken-Flote' columns operating at the Powell Mountain Coal Company, St. Charles, Virginia. he hyperbaric filter using 3 bar pressure and 165o cake formation angle, provided a filter cake with 23.6percent moisture with a throughput of 800 Kg/m2-h and air consumption of 868 Nm3/t (460 scfm/t). The vacuum filter with 30 percent submergence provided a filter cake with 27.8 percent moisture with a throughput of 122 Kg/m2-h. The screen bowl centrifuge provided a dewatered product containing 32.9 percent moisture at a feed rate of 450 Kg/hr, however, the solids capture was only65 percent. Addition of 1 Kg/t of a cationic surfactant provided filter cakes with 19.1 percent, 23percent, and 34 percent moisture using hyperbaric, vacuum, and centrifuge, respectively. Similarly, addition of 0.5 Kg/ton of copper chloride lowered filter cake moisture to 20.7 percent and 24.8percent, using hyperbaric and vacuum. With the centrifuge no improvement in filter cake moisture was noted. However, use of 80 Kg/ton of `orimulsion' in the centrifuge provided dewatered product containing 26 percent moisture, and the solids capture increased from 65 to 95 percent. The dewatered product appeared dry and was easily handleable.

Jan 1, 1999

By G. Krogman, C. Walla, B. Wood

The Gebo Mining District (District) is located in the Bighorn Basin of Wyoming. Commercial underground coal mining began in 1906 with the arrival of the railroad in Thermopolis, which is located approximately 11 miles to the south. Mining in the District ceased by the early 1970’s. In Fall of 1999, Lidstone and Associates, Inc. (LA) and their subcontractors were retained by the Wyoming Abandoned Mine Land Division (WyAML) to perform an inventory of over 500 abandoned mine sites across Wyoming. During the summer of 2000 field inventory, a 30-foot deep headcut (Figure 1) and sink-hole were noted in the West Fork of Sand Draw (WFSD), immediately west of the Town of Gebo. The headcut and sink-hole were located at the culvert outfall associated with a stream crossing of a relatively well traveled county road. Upon further investigation, it appeared that underground mine workings had been exposed at this location. This resulted in a condition whereby water would be conveyed directly into the mine workings during a runoff event. The exposed mine workings as well as stream capture created a very hazardous condition. The WyAML implemented mitigation measures in the summer of 2000 by constructing a temporary stream crossing upstream of the existing failed crossing. To address this hazardous situation as well as a number of other hazards identified in the District during the field inventory, the WyAML retained PHC Reclamation, Inc. (PHC). PHC was directed to perform a field investigation and develop a Reclamation Plan to address all existing abandoned mine hazards in the District. Federal, state, and private parties own lands within the District. Hazards identified during the investigation included an underground mine fire, open adits, open shafts, subsidence, drainage problems, and coal slack. A Report of Investigation (ROI) was submitted to various regulatory agencies that documented the existing conditions and conceptual reclamation plans to remediate the hazardous conditions. After review of the ROI by the US Department of Interior - Bureau of Land Management (BLM) an on-site meeting was conducted. BLM Cultural Resource personnel declined to approve a District reclamation project until a historical overview of the entire District was prepared. Due to the hazardous situation associated with the WFSD stream crossing, Hot Springs County Road and Bridge Department convinced various state and federal regulatory agencies to allow reclamation of the stream crossing to occur. A decision was made to allow reclamation on privately owned lands within the WFSD drainage. This decision limited the amount of channel that could be subjected to reclamation upstream of the crossing to privately owned lands. PHC contracted LA to perform a geologic, geomorphic, hydrologic, and hydraulic investigation of the drainage to assist in the development of a WFSD reclamation plan. LA’s investigation consisted of four parts: Delineate the extent of mine workings in the area; Identify all drainage structures that required mitigation; Survey a series of channel cross-sections and a longitudinal profile of the impacted channel; and, Develop basin hydrology to assist in the design of a stable reclaimed stream channel.

Jan 1, 2006

By Andy Alder

The aim of this paper is to provide an overview and details of good practice, from a United Kingdom perspective, in the development and implementation of major tunnel and underground infrastructure projects. In doing so, it draws on a broad base of project management theory. A central theme is that successful project delivery is dependent on detailed planning of the complete project delivery process, forming an effective team that works well together and the proper management of risk. The role of partnering in forming a strong project coalition is described. Particular emphasis is given to the integration of design and construction, and the role of the designer throughout the construction phase. The implementation of risk management in the design and construction of tunnel works is discussed, and recommendations are made on how risk, value and constructability can be integrated in project delivery. Recent practice in project procurement, particularly in the use of innovative collaborative forms of contract are described, and details of particular provisions for joint management of risk and problem resolution are provided. Finally, the relevance of the ITIG Code of Practice for Risk Management of Tunnel Works to good practice in project delivery is highlighted throughout the paper.

By S. Shrivastava, R. G. Reddy

Spent potliner is generated in the electrolytic process of reducing alumina to make aluminum metal using molten fluoride electrolytes. Spent potliner (SPL), obtained at the end of the pots life contains a small amount of cyanide and fluoride which present environmental problems. SPL became a listed hazardous waste under RCRA (KO88) in July, 1990. One of the possible uses of spent potliner is as a substitute for Calcium Fluoride (CaF2) as a fluidizer in iron- and steelmaking and in the glass industry. A low viscosity and a low melting point are prime requirements for accomplishing the above. In the present study, viscosity measurements were performed. Effect of various additives, such as sand, limestone, dicalcium silicate dust, and MgO baghouse dust on the viscosity of SPL was studied. The results showed that with the addition of sand and limestone, very high fluidity of SPL melt can be obtained at significantly low temperatures. The results suggest that spent potliner mixed with additives could potentially be used as a substitute fluidizer.

Jan 1, 1999

By JÖRG DEHNERT, PETER WINDISCH, Bernd Schönherrt, JENS STOPP

The Quick-Erect Stopping System (QESS) offers a new way of reducing the radon exposures of miners in Germany, especially during remediation work in old mines. The QESS is a light-weight, modular, and reusable construction kit of interlocking telescopic aluminum tubes, radon-proof foil, and expanding foam. It is designed to seal off radon-rich parts of galleries within only a few minutes. Originally, the QESS was developed to protect miners against radon exposures. Then, the QESS found the attention of several mine rescue teams at a German mining conference. The Student Mine Rescue of the Technical University Bergakademie Freiberg and the Wismut Mine Rescue carried out firstmine rescue drills in Freiberg and Schlema. Additionally, a mine rescue drill was carried out by the Front Range Mine Rescue in the Edgar Experimental Mine of the Colorado School of Mines. These drills helped to improve the systemand highlighted its potential for mine rescue operations. Now, the QESS is wellsuited for small-scale mining. The QESS can be used to seal off galleries in only a few minutes to both protect miners fromradon exposures and to support mine rescue operations. Moreover, the QESS was also successfully used in ventilation experiments.

Jul 23, 2020

By Robert S. Shoemaker

The development of a metallurgical project is a business venture rather than a technical exercise, and its real objective is to obtain the maximum return on investment consistent with the limitations imposed by company policy and the requirements of society. Demand for profits is the driving force for technical advances and naturally leads to improvements in processes, equipment and plant designs. In the mineral dressing field there have been virtually no new processes developed since the introduction of flotation, and the steady erosion of profits by inflation has been offset only by increasing equipment size. Unfortunately, in recent years, plant designers have not always utilized the largest equipment or the opportunities for functional and economic design presented by the development of larger equipment. Lower cost plants can be developed providing that unrealistic restraints arising from the prejudice of past practices are avoided. As an illustration of this premise, three different approaches were taken toward the design of a clearly delineated but hypothetical copper concentrator of 20, 000 tons per day capacity. While the same flowsheet was used in each case, designs were produced for a conventional plant, an alternate using the largest available equipment, and a third scheme utilizing large equipment and the most functional design which could be developed, including features derived from many plants in many different industries. Capital costs were developed for the three separate designs based on a location in the southwestern United States. Ancillary facilities were identical in each case and included a mine truck shop, a maintenance shop, a general office, and a nominal starter dam for tailings disposal within 5000 feet of the plant. Water supply within 1000 feet of the plant, and power furnished to the property boundary has been assumed in each case. The flowsheet of the three plants is shown in Figure 1 and represents the treatment of a typical sulfide copper ore by three- stage crushing followed by single-stage ball milling. Concentration is by flotation roughing and scavenging followed by regrinding of the concentrates and two stages of cleaning.

Jan 1, 1971

By R. L. Virta

Twenty-three companies mined kaolin in nine States in 2004. Production was estimated to be 7.6 Mt (8.3 million st) valued at $912 million, based on preliminary data. This was a slight decrease from 7.68 Mt (8.46 million st) valued at $939 million in 2003.Georgia was the leading producer state with an estimated 6.5 Mt (7.1 million st) in production. It was followed, in decreasing order of tonnage, by South Carolina, Alabama, California, Texas, Arkansas, Nevada, Florida and North Carolina. Georgia accounted for nearly the entire domestic water-washed, delaminated, and pigment-grade calcined kaolin production. Consumption Sales to the paper industry accounted for 49 percent of domestic sales and 64 percent of total sales. Other major markets for domestic sales were refractory products (10 percent), paint (5 percent), fiberglass (4 percent), catalysts (3 percent) and rubber (2 percent).Paper coating and filler markets accounted for about 87percent of export sales of kaolin.

Jan 1, 2005

Oil sands processing generates huge volumes of slurry, known as tailings, that is being stored in tailings ponds. The volume of produced tailings is a very important factor in oil sands surface mine planning, because the available area for dam construction is limited to the lease areas. On the other hand, oil sands operators cannot leave mine sites without reclaiming the tailings ponds. Since most of the reclamation material is generated in either oil sands mining or processing, it is reasonable to include reclamation material requirement as part of long-term mine planning. In this paper, an integrated optimization framework is proposed to maximize the net present value (NPV) of the produced oil sands, with respect to tailings capacity constraints and reclamation material requirements. A mixed integer linear programming (MILP) model is developed to find the optimal solution for long-term mine planning problem. A sample bitumen processing flow sheet is used to formulate the volume of produced tailings, based on Clark hot water extraction method. To verify the proposed model, it is coded in Matlab and run using CPLEX. Run results for real-case oil sands dataset show that the optimal production schedule meets material requirements for reclamation, tailings volume is within tailings capacity range in all periods and the production schedule follows the predetermined horizontal direction.

Feb 27, 2013

By Jordi Vives-Costa, J. J. de Felipe, Lluís Sanmiquel, Maria Niubó

The article evaluates the convective heat transfer coefficient of ventilation air in a potash mine. The energy balance is obtained through thermal characterization of the ventilation air and rock, allowing for the calculation of heat transfer parameters. Different models for calculating the convective heat transfer coefficient are analyzed. The results indicate that the Pethukov–Kirilov, Gnielinski, and modified Dittus–Boelter models are optimal for this mine. The study also indirectly examines the conductivity of the adjacent rock, suggesting saturation throughout the studied section and the presence of liquid water upwelling in a specific section.

Apr 7, 2022

By J. Gholamnejad

In open pit mine planning and design, push back mine sequencing is widely used for long-term production planning. In push back design, a series of nested pits is generated and then considered as possible push backs with regard to the minimum push back width requirements. These nested pits are produced by parameterizing on one economic parameters like commodity price, mining or processing cost, stripping ratio etc. The most important characterization of these push backs is that the inner most push back has the highest value per ton, the second inner most push back has the second highest value per ton and so on. These nested pits are generated based on the best estimates of grade within a representation of the ore body in a three dimensional matrix form. Therefore, the inherent uncertainty associated with reserve estimation (for our discussion grade uncertainty) is not taken into account when push backs are designed. These methods do not attempt to establish which part of the deposit is likely to be worth most. This paper introduced a new algorithm that incorporates ore grade uncertainty during push back design process. The suggested strategy tries to seek to schedule risky blocks later in the extraction sequence.

Jan 1, 2007

Mine Terex articulated dump trucks are working on a large restoration project of an abandoned open cast coal site in Blacklaw, central Scotland. The project is part of the construction of a 42-turbine wind farm complex. During the scheduled 18-month duration of the project, three 28-t(31-st) Generation 7 TA30 dump trucks and the six 36.5-t (40-st) TA40articulated trucks are estimated to move about 1Mm3 (1.3 million cu yd)of material. The trucks are working12-hour shifts, 5.5days a week.

Jan 1, 2005

By R. Gunda

Due to the rapidly increasing production rates and deepening of mine working areas, there is a drastic rise in the number of thermal issues to be addressed for maintaining a safe mine environment. As high temperatures and humidity in underground mines could affect the health and performance of workers, and ultimately the production rate, it is necessary to provide a properly controlled safe environment. The backfilling of stopes in metal, non-metal mines results in different thermophysical properties for the hanging, side and foot walls, modeling of which is not provided by any existing mine climate simulation software. This paper presents the modeling of such a single stope using the MULTIFLUX (MF) software, developed at University of Nevada, Reno. A special case is presented in this paper, where a case study from the Homestake mine in the US with a drift and ramp connected to a stope with high Virgin Rock Temperature (VRT) and various spot heat sources is modeled in MULTIFLUX and CLIMSIM, and the results are compared against each other. Another case is presented in which the stope of the previous cases is modeled with walls, each having a different set of thermophysical properties. These results are compared with the former results to analyze the effect of anisotropic properties.

Jan 1, 2011

By Kenneth N. Han, Peter Nam-soo Kim

A kinetic model for leaching of particulate metals in a batch system has been developed. The leaching mechanism has been analyzed by solving a series of ordinary differential equations relating heterogeneous reaction kinetics at the solid/liquid interface to mass transfer of reactant and products. Special emphasis has been given to the effect of changing of the surface area of the leaching substrate and initial particle distribution on the overall leaching rate. The dissolution of gold powders in acidic solution with bromine as an oxidant has been used as a model system. The effect of particle size, chemical reaction order, rate constant and mass transfer coefficient on the overall rate of dissolution of metal powder has been analyzed and discussed.

Jan 1, 2005

By Donald L. Everhart

The National Uranium Resource Evaluation (NURE) program since 1974 has been designed to accomplish a comprehensive coverage of the 48 conterminous States and Alaska to evaluate the total uranium resources of the USA. This resource base includes both ore reserves and potential resources. Techniques include airborne radiometric and magnetic surveys, by hydrogeochemical surveys, surface and subsurface geologic studies, and the application of improved geochemical exploration and resource assessment methods (Table 1). In brief review, the current status of each of the five basic NURE elements is as follows: In the Aerial Surveys, in the conterminous 48 states, the flying has been completed in 89 of the NTMS 10 x 2° NURE quadrangles, and is in progress in 39 more (Figure 1). Complete quadrangle data have already been open filed for 46 additional quadrangles, for a total of 174 for which data gathering is either complete or in progress. In Alaska, the flying is complete in 42 quadrangles, and quadrangle data have been open filed for 34 more, for a total of 76 (Figure 2).

Jan 1, 1979