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By B. Boberg

Annual requirements of uranium to fuel the 441 currently operating nuclear reactors in the world is 170 million pounds U3O8 (65,385 tonnes U). 2005 global production was 108 million pounds (41,595 t U), of which only 2.7 million pounds U3O8 (1,039 t U), was produced from US uranium deposits. US nuclear utilities represent 26% of the global nuclear capacity but only obtain 2.5% of their supply from US uranium mines. Since 2002 annual global production increased from 93 million pounds U3O8, a 15% increase and the US production increased from 2.3 million pounds to 2.7 million pounds, a 17% increase. Reasonably Assured Resources (RAR) of 12,332 million pounds U3O8 (4.7 million t U) are reported from a wide variety of countries and types of uranium deposits. This RAR suggests that there are significant global uranium resources potentially producible at a price of $50 per pound U3O8 ($130 per kg U). Table 1 shows the distribution of global uranium resources. This table, prepared from historic data maintained by the World Nuclear Association, does not include some areas of the world that are currently considered to contain significant resources of uranium such as Mongolia. Table 1 suggests that the United States contains the fourth largest uranium resource in the world with 890 million pounds U3O8, behind Australia, Kazakhstan and Canada in resources that are producible at a price of $50 per pound U3O8 ($130 per kg U). Within the US, the states that demonstrate the greatest amount of uranium resource are Wyoming, New Mexico, Texas and the Four Corners Area of Arizona, Colorado and Utah.

Jan 1, 2007

By D. R. Tesarik, T. C. Trancynger, W. G. Pariseau

The Davis detector cavern was excavated on the 4850 Level of the former Homestake Mine in the mid- 1960s to house a novel neutrino detector developed by Nobel Prize winner Dr. R. Davis. The original cavern was about 9.1 x 16.8 x 9.7 m high, excavated in a Precambrian amphibolite known as the Yates unit and enlarged in 2010. In 2009, the National Science Foundation selected the site for development as a national Deep Underground Science and Engineering Laboratory (DUSEL). This retrospective rock mechanics study of the Davis cavern is intended to inform design of the much larger caverns and laboratory rooms being considered for the same 4850 Level. Provision for rock mass variability, sequential excavation, jointing and wall damage from blasting are included in analyses that were done using two different computer codes and methods (FLAC3D and UTAH3). The results are in agreement with observations and show that cavern stability is indeed the case. The main conclusions are: (1) if conventional scaling of laboratory rock elastic moduli and strengths is done, then 0.25 and 0.50 scale factors are reasonable, (2) measured statistical and spatial variability in rock properties should be incorporated into geomechanical analyses to better reflect reality, (3) discontinuities (“joints”) are essential to reliable analysis of excavation safety and when properly taken into account eliminate the need for empirical “scaling” of laboratory rock properties, (4) major geologic features such as rhyolite dikes and breccia zones may be important to excavation safety at Homestake and should be explicitly represented in analyses and (5) quantifying wall blast damage is important to engineering design of underground excavations.

Jan 1, 2012

By H. W. Breathitt

World demand for phosphate rock has increased significantly in the past fifteen years. Prior to the early 1960's, most of the world production was obtained from Florida, North Africa, and Kola. As the 1960's arrived, new mines in North Florida and Eastern North Carolina, as well as expanded production in the Western United States, .increased domestic production. Many new mines overseas have also become significant. This includes countries such as Senegal, Togo, Israel, Spanish Sahara, and Jordan. Limited production, often as by-products, has been noted in South Africa, Brazil, and other countries. In recent years, and even recent months, we have learned of many new areas being considered as potential sources of phosphate rock. This includes Australia, Saudi Arabia, Mexico, Colombia, and Brazil. Many other developing countries have discoveries and are considering their new deposits, often with difficult beneficiation problems, as potential sources of phosphate. These factors all relate to expanded world, population and the demand for more fertilizer products to produce food. In this paper, four areas of the world with different types of phosphate deposits are briefly reviewed to contrast the ore beneficiation problems to Florida procedures--long considered the "standard" of the industry, at least for most of the United States' domestic production. Agrico has three large operating mines in Florida with total production capacity exceeding seven million tons per year. Here, pebble phosphate (+14 mesh material) is produced without the use of flotation, whereas all of the material finer than 14 mesh is subjected to flotation beneficiation to upgrade into high grade concentrates.

Jan 1, 1977

By E Marambio, R Brändle, G Fischer, G von Rickenbach, L Burgos, R Luis Fonseca

Ground support systems must provide safe and effective designs for underground excavations under high stress conditions. These systems must be capable to resist dynamic impacts and yielding during the loading process. In this context dynamic testing of the reinforcement and retaining elements that compose the ground support system are required to study and improve the behaviour of these elements under dynamic load events. During the last years, Geobrugg has been working on the improvement of retaining products by testing them in a large-scale impact test facility located at Walenstadt, Switzerland. The test facility is composed of a double level platform with a square-shaped pyramidal trunk geometry, in the upper level housing a loading mass that drop from a height up to 5m. The loading mass is guided by one central steel pipe, and the impact occurs in the sample to be tested located at the lower level in a slab with an area of 3.6m × 3.6m where the ground support system is installed. During the last years, this innovative facility has been used to test several configurations of ground support systems. The results of these tests have enabled to improve the understating of the behaviour of ground support systems under dynamic loads. In this manuscript, the arrangement, measurement, results, and the preliminary analysis of a single impact dynamic test performed during 2021 of a ground support system with a high-tensile steel wire mesh MINAX 80-4.6 is presented.

Apr 26, 2022

By G. Wang, L. R. Moore, Y. Xiong, J. Gu

"Quartz is the second most abundant mineral in the earth’s crust. Not only does quartz have many valuable industrial applications, it is also one of the most concentrated gangue minerals encountered in the processing of other minerals. Minerals such as hematite, apatite, calcite, feldspar, barite, and many more. Numerous applications of industrial minerals are sensitive to the hardness and abrasiveness encountered with quartz minerals, while other applications may lead to processing challenges for the end user. Therefore, process and chemistry optimization must be applied to ensure optimal grade is obtained for these valued industrial minerals. Extensive studies have been conducted in processing various industrial minerals, thus achieving a range of quality specifications, which entailed the application of ArrMaz’s CustoFloat and CustAmine collectors towards the separation of quartz from other minerals. INTRODUCTION Industrial minerals often have the misfortune of the gangue mineral being very similar in surface charge, and coordination properties, to that of the mineral of interest. An example is seen in phosphate beneficiation, when dolomite can be a gangue minerals (Table 1). Therefore, the development of processing reagents are quite complicated. Some minerals, like clays, may be washed away. However, most require the manipulation of the pH, in efforts to fine tune the system to the narrow difference in isoelectric points of the different minerals, as well as the knowledge, and resources that are necessary to exploit the differences to yield and an optimal grade/recovery. In some cases, the application of a depressant may be required, such as the phosphoric acid commonly applied to achieve the optimal balance of grade/recovery for phosphate from a mineral with elevated concentrations of dolomite (Wang, 2016), or the application of hydrofluoric acid to assist in producing feldspar product from a mineral rich in quartz (Heyes, 2012).ArrMaz's CustoFloat and CustAmine product lines have successfully been applied to the processing of industrial minerals for more than 50 years. Applications include, but not limited to phosphate, sand (glass, foundry & high purity quartz), clays (feldspar, kaolin, etc.), and many carbonaceous and sulfate minerals. The successes of these 50 years are largely due to ArrMaz's ability to tailor make the processing chemistries to fit the ever changing and declining mineral feed grade and variations in water quality (Moore, 2015; Moore, 2016). This technical knowledge of mineral processing is strongly complimented by the intimate service programs in place at many of the beneficiation plants."

Jan 1, 2018

By Bijan Taheri, Behrouz Maghsodi, Monireh Heshami, Reza Kohan

A common problem recently encountered with the increase in the rate of input feed at Enrichment Plant 2 of the Sarcheshmeh Copper Complex is the loss of value to the tails, translating to lower recoveries. The feasibility of the direct transfer of part of the high-grade concentrate from rougher stages to an appropriate position along the circuit was studied, and two positions were proposed for direct transfer of the concentrate. One position was the feed flow into cleaner cells, and the other was the feed flow into the recleaner cell. The results indicated that transferring the concentrate from the first unit of the rougher stage to the feed flow into the cleaner cells was feasible, with no limitations, while the second position required the installation of a set of hydrocyclones. It was found that the transfer of concentrate to the proposed positions not only addressed the problem of limited cell capacity, resulting in debottlenecking of the circuit, but also improved metallurgical separation efficiency up to 1.4%.

By B. J. Arnold

Prior laboratory work has demonstrated -that much of the fine ash-forming minerals entering a flotation froth are there as a result of water carry-over from the bulk contents of the flotation cell (Arnold and Aplan, 1986a). Using a bank of four 300 cu ft WEMCO flotation cells cleaning a well-liberated Lower Kittanning seam coal, test results show that the sulfur and ash content of the froth is directly related to the water content of the froth (or inversely related to the percent of solids in the froth). Reagent changes which result in a watery froth produce a higher ash content in the froth. A direct comparison of laboratory and plant results show that the standard laboratory flotation test produces a product higher in sulfur and ash than that produced in the plant. Caution should be exercised when extrapolating laboratory test results to the plant situation. A method of estimating coal flotation product quality in the plant based on laboratory tests is given.

Jan 1, 1990

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 Sandy Worden

Coal mining companies in Australia are managing the high-consequence risks across their operations more effectively by using an interactive online risk management system known as Riskgate Developed by the Minerals Industry Safety and Health Centre (MISHC) at the University of Queensland, Australia, Riskgate contains detailed information about 11 high-consequence risk areas (called topics in the system) for opencut and underground coal mines (Table 1). The existing topics are: fires; strata control for underground mining; ground control for opencut mining; tires; isolation; collisions; explosions and explosives; manual tasks; and trips, slips and falls. Every Riskgate topic is focused on coal industry activities (mining, processing, transport and storage). The scope includes mine sites, lease areas and mine infrastructure (mobile, fixed plant, field equipment, buildings, road and rail transport), and all aspects of the mine life cycle from design through to decommissioning. The topics uniformly recognize that a loss of control can result in injury or fatality, equipment damage, production loss, reputation loss and environmental damage. However, the priority focus for Riskgate is the safety of mine personnel.

Jul 1, 2013

By E. Forssberg

Studies have been carried out with the High Pressure Roller Mill, HPRM, to produce calcium carbonate minus 10 micron. This paper presents the optimization of the specific grinding force of the HPRM system for a maximum energy utilization when limestone is ground. In addition, experimental tests of producing carbonate minerals using the HPRM as a pre-crusher are described in this paper.

Jan 1, 1996

Thermal pretreatment can significantly improve industrial comminution operations by reducing energy requirements and increasing mineral liberation. The effect of pretreatment using conventional and dielectric heating followed by quenching on the fracture properties of a number single and multiphase brittle materials has been investigated. The reduction in the impact fracture energies and particle strengths with and without pretreatment has been measured in precise single-particle experiments using the Ultrafast Load Cell. Variations in the fragmentation pattern caused by different pretreatments were assessed by measurements of the progeny size distributions. The differences in the effect of thermal treatment on single and multiphase materials are discussed based on the experimental results.

Jan 1, 1995

By James J. Anthony

High-angle in-pit conveying is an idea that is being seriously studied by a number of important mining companies in North America. Its application in coal, iron ore, and copper mining is expected to reduce mine operating costs considerably compared with the conventional discontinuous methods, such as truck haulage, which are fuel, labor, and maintenance intensive. Therefore, a mine introducing high-angle in-pit conveyors will gain a competitive advantage over mines which continue to use conventional haulage. While the capital outlay for in-pit conveyor systems obviously varies depending on pit depth, the angle of incline, and the capacity required, it generally will not exceed that of truck haulage when all Factors are taken into consideration. These factors include the cost of excavation, as measured in relation to the volume of minerals mined, the cost of building truck ramps and roads, and the capital outlay for the trucks and maintenance facilities. In many cases, in Fact, the capital outlay will be less than for truck haulage. This cost advantage will best be realized by new mines, whereas in existing producing mines the switch from truck haulage may involve the abandonment of a substantial capital asset.

Jan 1, 1983

By S. Frisch

Selenium (Se) in effluent waters has become a significant challenge for a number of industries. Toxicity studies and new reports of occurrence have certainly caused increased scrutiny and actions in the mining industry today (Sandy, DiSante, 2010). While initial activity in addressing selenium-laden waters were conducted in the coal mining industry, today a much broader range of mine types are beginning to search for solutions to selenium treatment of their mining waters, including both hard rock mining operations (gold, nickel, zinc, etc.) and soft rock mining (phosphate, uranium, etc.) Throughout North America, new regulations covering selenium discharge are either in place or being developed. While a number of physical/chemical approaches show promise in selenium treatment, when considering optimal cost and treatment efficacy issues, biological treatment ? particularly fixed-film biological treatment - is reported to be one of the most promising approaches to managing selenium-containing waters. Among biological treatment options, the fluidized bed reactor (FBR) has undergone extensive pilot testing for Se treatment in the last three years, including eight pilot programs, and the first FBR system is now operating at a coal mining site. In all tests, the FBR has been shown to be a highly cost-effective approach to selenium treatment based on its physical and performance characteristics. This is consistent with its history for reaching low levels of treatment in similar service for other oxyanions including perchlorate, nitrate and various metals. With the results from the most recent testing, the technology has been shown to be adaptable to an ever-broadening range of influent water conditions and flow rates, in varying terrains and weather conditions. Selenium occurs in various valence states from -2 to +6 (Sobolewski, 2005). The speciation of selenium plays a critical role in understanding the effectiveness of any approach for removal, especially to low levels. Elemental selenium is insoluble and has little effect on living organisms. Colloidal fractions are known to occur. In aqueous environments such as coal mining runoff, selenium is most often found as the oxygenated anions of selenite (SeO32-, Se4+) and selenate, (SeO42-, Se6+). Selenium is commonly found in mining waters in concentrations ranging from 3 to >12,000 µg/L. The U.S. National Primary Drinking Water Standard MCL is 50 µg/L for selenium (EU 10 µg/L; WHO 40 µg/L). The National Fresh Water Quality Standard is 5 µg/L for selenium. The U.S. Fish and Wildlife Service has recommended that the National Fresh Water Quality Standard be lowered to 2 µg/L to protect fish, waterfowl, and endangered aquatic species. Several states have followed with enforcement actions at these same low levels. In Canada, permits may require stakeholders to monitor levels in water or biota, or to comply with guidelines, at either the National or Provincial levels, which can be as low as 1 or 2 µg/L in surface waters. Treatment of selenium in all mining waters presents a series of challenges. It can be present in relatively dilute concentrations and in streams with variable and often high flow rates. It can be present in many soluble and particulate forms, which may affect process design and treatability. The conditions of influent selenium-containing waters can vary, with issues such as temperature, pH, total dissolved solids and other contaminants affecting the ability to remove selenium selectively and economically. Treatment of selenium often results in the generation of a concentrated by-product requiring disposal, and re-release from residuals can occur. Beyond these issues, the physical environment of a mining operation can offer challenges such as remoteness and harsh and/or cold weather. Currently available selenium treatment technology (Table 1) includes biological treatment and a number of physical-chemical processes ? such as ion exchange, membrane filtration and adsorption ? that vary widely in efficiency and cost. Most treatment options remain either too costly and/or unproven for selenium-containing streams for reasons that include poor removal efficiency, variability in volume and composition of influents, system sizing and logistics considerations, as well as operating requirements.

Feb 23, 2014

By Robin J. Batterham, Dave J. Robinson

The history of mineral processing in general and flotation in particular is long and has always been tied to mining methods of the day. Building on the ever-improving fundamental understanding of the underlying science, the most significant trend in flotation has been the putting into practice the learnings from trailblazers such as Professor Fuerstenau that has given the confidence that enabled an ever-increasing scale of operations. There is, however, doubt this ongoing trend is enough to maintain the economics against global trends such as that of falling grades, increasing mining costs, pressure on water supply and demand, rising energy demands needed for mineral processing, and a focus on whole of life value and mine legacy issues. In addition, we see that globally, the social license to operate for mining (and hence mineral processing) is far from secure and, at the very least, is under much more rigorous scrutiny. In this paper, we comment on the ramifications of broader uptake of more sustainable mining for mineral processing methods and address the specific question of whether recent progress in in-place recovery will lead to a timely breakthrough. The answer proposed is that this is possible in the next 10–20 years but in the meantime, the focus is just as likely to be on removal of waste (beneficiation) much earlier in circuits. Either way, mineral processing and flotation, as we know it, will change significantly.

By W. M. Schafer

The risk that water quality will be degraded by mining activity can be evaluated using risk analysis techniques. Water quality impacts can occur where water-rock interactions with tailings, waste rock, or leached ore lead to increased loading of constituents into surface or groundwater. Constituent loads contributed by mining facilities are determined by the migration route and chemical evolution of mine water. Mass load contributions from mines can be determined by estimating the prototype pore water in contact with mining waste, predicting the rate and timing of flow, assessing the degree of geochemical attenuation, and modeling chemical mixing with natural surface or groundwater. Mining facility siting and design measures can alter the chemical evolution of mine water by varying the quantity or quality of flow. Stochastic risk management techniques provide a powerful tool for quantitatively identifying the environmental consequences of various siting and design alternatives.

Jan 1, 1998

By Micah Nehring, MEHMET KIZIL, Farzad Sotoudeh, Amin Mousavi, PETER KNIGHTS

Production scheduling in underground mines is one of the most important and complex processes in maximising the economic value of an operation over the life of the mine. Due to increasing energy, transportation, processing and smelting costs and reducing water availability, the extraction of ore deposits through underground operations has become more expensive and challenging. A potential productive and efficient solution to mitigate these issues is to integrate pre-concentration systems into the existing mining system to increase ore grades through a preliminary process of rejecting some waste before sending the ore to the energy intensive mineral processing plant. Further benefit of such systems includes the utilisation of the waste and low-grade material in backfilling of open stopes to reduce the transportation costs and surface environmental impact such as reduction of CO2 emissions and waste transportation. The objective of this paper is to present a new mathematical model to optimise the production schedule of underground metalliferous mining operations in the presence of a pre-concentration system. The proposed model optimises the production schedule and sequencing of stopes within a sublevel stoping operation. The results of this study illustrate the potential economic benefits of using a pre-concentration system prior to a mineral processing operation as a result of increased net present value.

Nov 16, 2023

By M. Werner

Mining in the Coeur d'Alene Mining District has been going on for over 100 years with a long- term continuation very likely. Mining is presently carried out at depths below the -5000' horizon. As mining continues at ever increasing depths, higher in-situ rock stresses and subsequent rock deformation is encountered making mining costly and hazardous. To provide access for men and materials in such areas, a wooden raise preparation structure is typically built. Although these structures provide adequate support and access, they have proved to be very costly to construct and maintain.

Jan 1, 1986

By Harvey P. Knudsen

This paper illustrates the application of geostatistics to a roll front type uranium deposit located in Wyoming. The steps involved in calculation of experimental variograms, variogram modeling and verification of the resulting models are described in detail. The resulting spherical variogram models for grade thickness and thickness show strong geometrical anisotropies. The major axis of anisotropy for both variables is approximately parallel to the axis of the roll front and the minor axis perpendicular to the roll. This model confirms the technique of drilling "fences" across the roll front, where the drilling is much closer together than the fences along the roll.

Jan 1, 1978

By V. M. S. R. Murthy, Biswaraj Dash, Somnath Chattopadhyaya

Tunnel boring machine (TBM) has been in focus for the last few decades and is currently the most preferred excavation method for metro, hydro and irrigation tunnels. Tunnelling in hard and abrasive rock conditions, in particular, is adversely affected by a very low advance rate coupled with increased TBM disc cutter failures and cutterhead jamming, seeking an in-depth understanding of the design and operational processes of the boring components of the TBM. The cutterhead and disc cutter are the critical boring components of the machine, influencing the boring process significantly. These components directly interact with the rock and hugely influence the machine’s efficiency. This paper encapsulates a review of prior studies related to disc cutter design and the cutterhead design for hard rock TBM tunnelling. A design methodology for designing and selecting a disc cutter and a cutterhead is suggested. The design methodology has been applied for a hard rock tunnelling case, and suitable design specifications for the boring components were arrived at. The disc cutter and cutterhead specifications designed based on the suggested methodology closely match with that of deployed TBM specifications. It may be observed that except for the case of high-strength and high-abrasive rock (greyish quartzite), for the rest of the rocks, the suggested design can meet the desired advance rates.

Jan 31, 2024

By J. S. Wozek

In metallurgical applications, coal fulfills dual roles as a chemical feed stock and as a fuel source. These applications range from cokemaking, ironrnaking (including pulverized coal injection), foundry, basic oxygen furnace / electric arc furnace coal additions, direct ironrnaking, Corex, and the futuristic direct steelmaking. In all steelmaking related processes, chemical reactions are simultaneously temperature and chemical dependent. Therefore, coals used in these processes must consistently comply with specific quality parameters in order to promote efficient operations. This paper limits discussion of Metallurgical Coal Quality to cokemaking and ironmaking applications. Its purpose is to present the customer's perspective on the control of critical coal and coke properties.

Jan 1, 1994