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By A. Singh

"Considering the dominant role of fertilizers in global phosphate production, it is evident that with the ever increasing development in agriculture there will be a growing demand for phosphate beneficiation. With the rapid depletion of high quality reserves, investigations into more complex and lower grade ore bodies are required. The Minerals Processing Division at Mintek has been involved in process development and flowsheet design projects on phosphate resources since 2003. This paper will discuss the processes that Mintek has explored and employed to upgrade various phosphate ore bodies (>30% Phosphorous Pentoxide (P2O5)) in preparation for end user application. These are aimed at an improved understanding of ores in terms of their varying mineralogy and the development of appropriate process routes to meet product specification. OVERVIEW OF MINTEK Mintek is a state owned science council that undertakes R&D, consulting and sells products and services into the minerals beneficiation industry. Mintek has been in existence for 83 years with a current permanent staff complement of 750 of which 300 are professionals with a tertiary education. Being a non-profit organisation, the majority of funding comes from state grant and earmarked funding. All research is needs-driven exploring innovation through technology and process optimisation trends. Owing to a solid base of expertise, extensive laboratory and pilot facilities, and a historical database of knowledge, Mintek is well positioned and equipped to execute projects on a scoping, feasibility, prefeasibility and bankable level. USES OF PHOSPHATE Phosphate is the component in fertilizer essential for root and stem development in plants as well as rejuvenation of harshly depleted soil for which there is no agricultural substitute. Phosphate rock is essential for global food security with 87% used in the production of fertilizers. In agriculture as fertilizer, phosphate is one of the three primary plant nutrients in addition to nitrogen and potassium. In former times, it was simply crushed and used as is, but the crude form is now only used in organic farming. Normally it is chemically treated to make Single superphosphate (SSP), Triple superphosphate (TSP), or Mono-ammonium phosphates (MAP) and Di-ammonium phosphates (DAP), which has a higher concentration of phosphate and is more soluble, thus more suitable for plant absorption."

Jan 1, 2018

By G. Schriever, H. Thiel, E. J. Foell

A long-term, large-scale, disturbance-recolonization experiment with relevance to the environmental effects of deep seabed mining is described. The study is funded by the German government and was launched in the abyssal eastern tropical South Pacific Ocean in February-March, 1989. After obtaining pre-impact baseline environmental data, a 10.8 km2 (4.2 sq miles) circular area of seafloor was disturbed using a specially designed "plow-harrow" device. An initial post-impact sampling series was carried out immediately after disturbance followed by a second post-impact sampling series six months after the disturbance. Plans call for repeated visits to the site at two year intervals to monitor the anticipated slow recolonization process until the area is inhabited by a new, stabilized community.

Jan 1, 1993

By Michael P. Connor, O&apos

The Wing Hill Garnet Deposit, located near Rangeley, Maine, forsed through assimilation of Early Paleozoic metasediments by an intrusive Devonian gabbro. The resulting ore body is exceptionally large and high-grade, consisting of 50-70% almandine garnet. Following open-pit quarrying, the ore is trucked to Industrial Garnet Extractives' mill in West Paris for final processing. Two grades of abrasive are produced - a pure, premium grade INDUSTRIAL GARNET and the Lower grade co-product IGE UTILITY GRIT, both of which are available in a variety of sizes. INDUSTRIAL GARNET is marketed world- wide into a diverse marketplace including both loose grain and bonded applications.

Jan 1, 1985

By Y. J. Zhang

This paper presents the results of a recent study on the development of an in-situ testing method for determining the coal strength in mine pillars. The strength testing is performed in the horizontal holes drilled into the coal rib using the penetrometer. It is a hydraulically powered device that uses an indenter to press the surface of the borehole until the load reaches the failure point of coal. The pressure and the penetration of the loading pin are recorded by the data acquisition unit. The results collected from several coal mines indicate that this testing method is ideally suited for the realistic coal strength measurements. The new testing system not only improves the accuracy of pillar strength determination, but it is more cost efficient than the conventional method.

Jan 1, 1995

By Lloyd B. Underwood

In the event of a sudden nuclear attack upon the United States, it is imperative that vital command and control centers have a high probability of survival. One such vital facility is the North American Air Defense Command Combat Operations Center at Colorado Springs, Colorado. Known briefly as NOW, this installation when completed will be housed in large chambers excavated out of granite beneath the eastern slope of Cheyenne Mountain (Figure 1). The NORAD COC, a U. S. Air Force sponsored project, will serve as the primary collection and evaluation center for data concerning unknown aircraft, missiles, or space vehicles, which might bring destruction to North America. The data will be fed into high-speed computers and electronic equipment from outpost sources - radar, ballistic missile early warning stations and picket ships throughout the world. Electronically controlled display boards will make it possible to evaluate the tracking data instantaneously and to take appropriate defensive action1.

Jan 1, 1965

By Bill S. Taylor

Dutch State Mines [D.S.M] introduced the Heavy Medium Cyclone into the United States for cleaning fine coal about three decades ago. Since that time the general industry practice has been to deslime the raw coal at 28 Mesh (0. 59mm) size. The plus 28M material is fed to the Heavy Medium Cyclone for cleaning, and the 28M x 0 fraction is processed by other means (e. g. flotation or hydrocyclones). This approach recognized that 28M was the smallest size particle that could be easily rinsed on vibratory screens without excessive loss of magnetite, and without blinding of sieve bend and vibratory screen decks. Another reason for the 28M de-sliming was to avoid excessive contamination of the media with non-magnetic coal, shale, or clay fines. The most undesirable of these contaminants is the sub-micron size clay particles (2) that greatly increase the viscosity of the media and reduce the numerical maximum level that the media specific gravity can obtain due to the lower specific gravity of clay with respect to magnetite. The higher the fugitive clay content, the more severe the preceding problems become. During the last 30 years, many conventional Heavy Medium Cyclone Plants have been built throughout the world. In the United States, the initial cyclone plants were confined to the production of high quality metallurgical coal where lower gravities of separation were required than could be obtained from the conventional hydraulic or air separation processes. In recent years a large and ever-increasing number of preparation plants producing steam coal have started utilizing Heavy Medium Cyclone technology due to the environmental pressures being encountered to produce low sulphur coal. Due to the inherent characteristic of many coals of having a lower pyritic sulphur content at lower specific gravity fractions, many applications and markets are appearing for separating steam coals at much lower specific gravities than have been historically normal in the United States. Therefore. Heavy Medium Cyclones are being utilized to a much greater degree in this field, due to the flexibility of low separating gravity ability coupled with high efficiency when high percentage of near gravity material is present.

Jan 1, 1978

By E. R. Mueller

The natural lives of machines and components vary tremendously! Maintenance managers struggle constantly to maximize their equipment lives while minimizing their maintenance costs, but they normally lack the tools and techniques they need to do this properly. This paper proposes a methodology based on probabilities of failure and expected values for repairs that recognizes the variation among individual machines and components as well as the high costs associated with catastrophic failures. It enables a user to determine the optimum change-out intervals for many types of equipment. The approach proposed here is sophisticated enough to be reliable but simple enough to be applied by the maintenance staff on the shop floor. It will complement existing preventive and predictive maintenance programs.

Jan 1, 1995

By K. H. Nimerick

A unique freeze conditioning agent (FCA) which functions by forming structurally weak ice rather than suppressing the freezing point of water has been successful in alleviating frozen coal problems. Frozen coal treated with FCA has been quickly unloaded at temperatures below -17.SoC (O°F). Other areas where FCA has found utility has been de-icing conveyor belts, idler, idler arms and other moving parts that have been impeded by ice.

Jan 1, 1977

By M. A. Bartkoski

Today?s surviving companies are being pushed to a heightened level of excellence due to market changes. Therefore, new business strategies must be explored. This paper offers a sequenced plan to retool, empower, and organize the entire team for a common goal. Integrity Process is an operating system that is very comprehensive and is integrated in every part of the business. It relies on a detailed prevention concept intertwined with accountability that produces individual efficiencies and team effectiveness. Integrity Process focuses on the importance between working from commitment motives versus compliance fears. The results are balanced in priority and truly yield a win-win for the owners, management, workforce, and the community. Integrity Process can and is being used in any industry that is challenged to optimize the relationship between people and process.

Feb 23, 2014

By A. Robison, V. T. McLemore

"The San Juan Basin, New Mexico contains many heavy mineral beach-placer sandstone deposits of Cretaceous age. Beach-placer sandstone deposits are concentrations of heavy minerals that formed by mechanical concentrations (i.e. settling) of heavy minerals on beaches or in longshore bars in a marginal-marine environment. They have high concentrations of several elements, such as Ti, Zr, rare earth elements (REE), Sc, Y, U, Th, Nb, Ta and Fe. These elements are becoming increasingly more important to industry, because they are used in the manufacture of devices our society uses every day, i.e. cell phones, computers, and alternative energy devices, like solar panels. It is unlikely that any of the beach-placer sandstone deposits in the San Juan Basin will be mined in the near future because of small tonnage, low grades, high iron content, and distance to processing plants and markets. However, as the demand for some of these elements increases because of increased demand and short supplies, the dollar value per ton of ore rises, enhancing deposit economics. Current studies at the New Mexico Bureau of Geology and Mineral Resources are focused on the Apache Mesa (formerly Stinking Lake) deposit near Dulce, New Mexico. INTRODUCTION Beach-placer sandstone deposits are accumulations of heavy, resistant minerals (i.e. high specific gravity) that form on upper regions of beaches or in long-shore bars in a marginal-marine environment. They form by mechanical concentration (i.e. settling) of heavy minerals by the action of waves, currents, and winds (Fig. 1; Bryan et al., 2007). Modern examples are found along the Atlantic Coast, USA (Koch, 1986; Carpenter and Carpenter, 1991), southeastern Australia (Roy, 1999), and Andhra Pradesh, India (Rao et al., 2008), where they are mined for titanium, zircon, and monazite (a Ce-bearing rare earth, REE, mineral). Detrital heavy minerals comprise approximately 50-60% of these sandstones and typically consist of titanite, zircon, magnetite, ilmenite, monazite, apatite, rutile, xenotime, garnet, and allanite, among other minerals. Most of these minerals have a high specific gravity exceeding 4 and are dark colored, giving the sandstones a dark color, resulting in them being called black sandstones. Although beach-placer sandstone deposits are found in strata of all ages; the deposits in the San Juan Basin in New Mexico are restricted to Late Cretaceous rocks belonging to the Gallup, Dalton, Point Lookout, and Pictured Cliffs Sandstones (Fig. 2; Table 1; Chenoweth, 1957; Houston and Murphy, 1970, 1977). The beach-placer sandstones are black, dark gray, to olive-brown, resistant to erosion, and radioactive due to radioactive zircon, monazite, apatite, and thorium minerals. Anomalously high concentrations of Ti, Fe, Nb, Th, U, Zr, Sc, Y, and REE are characteristic of these deposits. Similar Upper Cretaceous heavy mineral, beach-placer sandstone deposits are found throughout Montana, Wyoming, Utah, Arizona, and Colorado (Dow and Batty, 1961; Houston and Murphy, 1970, 1977; Zech et al., 1994)."

Jan 1, 2016

By Chao Zhang, Wenhao Xia, Jianxin Fu, Ling Yu, Weidong Song, Yang Li

Sanshandao Gold Mine is the only undersea metal mine in China. To deal with the collapse and pumping of stopes and roadways caused by complex ore-rock occurrence conditions, the mine conducts filling and sealing of some areas, and the remaining ore reserves will be mined after treatment. Therefore, it is urgent to evaluate the stability of rock masses, fault fracture zones, and aquicludes during the secondary mining process. In this study, displacement and microseismic methods are employed to monitor rock deformation and fractures. Additionally, FLAC3D was used to simulate the process of secondary mining, reproducing the evolution of stress fields, displacement fields, seepage fields, and plastic zones at different mining stages. The combination of numerical simulation and on-site monitoring verification demonstrates that the deformation of surrounding rock presents a rapid growth at the initial stage of mining, followed by a gradual decrease in the growth rate, and finally tends to stabilize; the fracture zone area at the 151–159 exploration line on the − 320 m level (near the 7# and 8# stopes) exhibits poor stability, and monitoring measures should be strengthened; the deformation value of the aquiclude is less than the deformation value of I protection level in the Code for Design, the impact of secondary mining on the aquiclude is limited; fault and fracture zone deteriorate rock mass stability, and their impact is related to their spatial locations. Hanging wall fault has a more significant impact on the settlement of the aquiclude, while the footwall fracture zone has a greater impact on the development of the plastic zone.

Feb 21, 2024

By C. M. Goodall

Solids and liquid phase residence time distribution data is reported for a laboratory column flotation cell. The effects of various physical flotation parameters on residence time distributions are reported and analyzed. A plug flow model with recycle is proposed for the froth phase and a tanks in series model for the pulp. By comparison of two and three phase residence time -distribution data it has been shown that the use of liquid residence time distribution data to predict the residence time distribution of the solids in a column is not valid.

Jan 1, 1990

By A. Suarez, M. Menendez, M. R. Gent, P. Riesgo

"Recent requirements to reduce thermal coal plant emissions, and ultrafine coal's tendency to produce these emissions due to its typically high ash and moisture contents have limited the use of ultrafine coal. Ultrafine coal in beneficiation plants are usually either disposed of in tailing ponds at a loss in combustible material or disposed of by blending with coarser higher-grade products, resulting in a reduction in marketed product quality. A study of the options for processing ultrafine coal, consisting of < 200 µm hydrocyclone overflow, with 38.8 percent ash content is presented here. Ultrafine coal was processed based on 200-µm sieve bend and 10-µm hydrocyclone classifications, enhanced gravity separation (EGS) and froth flotation concentration as well as combinations of these. Yield, combustible material recovery (CMR) and product humidity were evaluated as test results.Depending on the processing applied, product ash content could be reduced up to 49.7 percent, and up to 95.8 percent CMR of the actual run of mill feed could be attained. All of the processing options analyzed could reduce produced thermal electric plant emissions due to ash and moisture from 22 to 38 percent of the actual unprocessed ultrafine coal product.Froth flotation was found to be the optimal process, yielding a product with the lowest ash content attained of 19.5 percent and CMR of 92.3 percent. Being the most versatile of the processes evaluated, it is capable of producing coal with varied ash contents but is subject to potential variations in coal flotability. The most complicated of the processing options, a combined sieve bend recovery of the > 200 µm fraction and EGS processing of the 10 to 200 µm fraction was found to be the next best option, attaining a combined 90.1 percent CMR and 25.0 percent ash content. IntroductionMunicipal, regional and national objectives to reduce fossil fuel combustion emissions and their effects on air quality and global weather changes are affecting thermal electric plant operations. Plans and regulations such as President Obama's Clean Power Plan (U.S. Environmental Protection Agency, 2015), the European Directive 2010/75/EU (European Commission, 2010) and China’s proposed Enhanced Actions on Climate Change (Wei, 2015) are of major significance to thermal electric plant operations. Although thermal plant efficiencies depend in large part on the losses of heat by plant components, the ash and humidity contents of thermal coal invariably reduce plant efficiencies and increase emissions of carbon dioxide (CO2), nitrogen oxides (NOx) and dust.Any noncombustible material present in thermal coal will result in higher CO2 emissions per unit of energy produced. Since no particle emission control can be totally effective, it is to be anticipated that any reduction in coal ash content will also result in reduced particle emissions. Kurose, Ikeda and Makino (2001) reported that NOx emissions also increase with coal ash content. The effect of coal moisture content during combustion is complex. Kurose, Ikeda and Makino (2001) showed that an increase in coal moisture content significantly reduces thermal NOx to total NOx production, and Bosoaga et al. (2006) showed that it tends to reduce NOx emissions. Since the humidity, pyrite and ash content of thermal coals directly affect thermal electric plant efficiencies and emissions, minimizing these factors should facilitate, at least in part, compliance with thermal electric plant emission limits. This, in turn, would affect the specifications and prices of the coal preparation plant products."

Jan 1, 2016

By R. R. Klimpel

The use of chemical reagents in flotation has been studied in great detail, e.g. (1, 2, 3, 4). Important progress has been made on the understanding of surface chemistry concepts involved in flotation. However, such scientific studies are often very complex even for rather simple idealized systems. Therefore, the deve- lopment of predictive or quantitative tools for plant engineering evaluation is still in the evolutionary stages. Until further progress in fundamental work is achieved, the operating engineer is faced with semi-empirical physical testing of reagent changes on several sizes of the actual equipment under study to be confident of the economic viability of any change.

Jan 1, 1980

By T. H. Combs

Increased productivity in the U.S. underground coal industry has taxed pre-existing conveyor belt haulage systems. The usual remedies are costly and can disrupt production. A reduction in the belt feeder discharge rate on mobile haulage sections results in more uniform loading and reduces the spillage vulnerability. An investigation is made to determine the effect, if any, on shuttle car discharge time arising from lower feeder discharge rates. A five-section, underground mine is visualized, and belt spillage is introduced. The sectional feeder discharge rate is progressively lowered until spillage is precluded. At each level, the simulated spillage is measured and compared to the loss in face production. Methods of predicting the loss in face production from lower feeder discharge rates are discussed.

Jan 1, 1993

Maximizing margins in competitive markets demands superior productivity. Unfortunately, management systems developed early this century for other industries often drive counterproductive behaviors choking mining productivity. Many executives and managers waste valuable time and effort relying on simply training and communicating to improve managerial practices and attitudes. In covering practical human behaviour, the paper explains why this fails -and explains how to use systems to successfully drive improved managerial practices and attitudes. It highlights use of modern performance Measurement, Analysis and Reporting systems to drive behaviors and improve margins -without capital investment -and make executive and managerial work easier and more effective.

Jan 1, 1999

By D. Akers

Many of the trace elements found in coal are associated with mineral matter, making it possible to remove them by physical coal cleaning. As part of work funded by the Electric Power Research Institute, both conventional and advanced coal cleaning processes were found to provide large reductions in the concentration of many trace elements that, if released into the atmosphere, are considered to be potentially toxic or environmentally harmful. Advanced physical cleaning technologies appear to provide greater reductions than conventional technologies. Chemical cleaning processes may also remove many trace elements, possibly including organically-bound elements such as beryllium. Care must be taken in the disposal of coal cleaning plant refuse because oxidation and leaching of this material can create highly acidic leachate and many trace elements are mobile in an acid environment. Laboratory leaching procedures are potentially useful in determining the degree of risk of water contamination by trace elements should an acid environment form.

Jan 1, 1992

By Harry Perry

U. S. consumption of sulfur and sulfur products is expected to increase at a rate of 8 percent per year between now and 1980, largely as a result of their use in fertilizer markets. World consumption is also increasing rapidly, but at a-lower rate, about 6-percent per year. In 1965, sulfur recovered in the United States from purification of natural gas; nearly doubled from the 1956-1960 average; production from pyrites declined; and production of elemental sulfur increased 15 percent. Concern about air pollution resulting from sulfur oxides produced from the combustion of fossil fuel has lead to intensive research on methods of removal before combustion, during combustion (in-process methods), and from the resulting flue gases. If all the sulfur in fossill fuels were recovered, more sulfur products would be produced than were consumed in the United States in 1965. Removal of sulfur from coal before combustion could result in a product sufficiently-high in sulfur to be a suitable raw material for sulfuric acid manufacture. In-process methods produce solid sulfates, some of which may have commercial value. Flue gas removal&apos; methods for sulfur oxidest generally result in the production of a byproduct either of sulfuric acid or sulfur. The projected sale of these materials significantly lowers the anticipated cost of sulfur dioxides pollution abatement. Alternate methods for sulfur dioxide reduction are discussed. The various proposed processes are described and costs are given for the various methods for which estimates have been made.

Jan 1, 1967

By Dean Newman, Michael Behrens, Mark Trim, Justin Arifin

Road tunnels in recent infrastructure projects in Sydney, Australia, are designed to have a fire resistance level of either a 4-hour cellulosic fire or a 2-hour hydrocarbon fire. Where permanent ground support for tunnels consists of systematic rock bolts and relatively thin layer of shotcrete, it is important to ensure that during and after the fire event the ground support is designed/predicted not to pose risks to the tunnel occupant. The global behavior of the ground support can be predicted using finite element analysis, and its resistance is derived with consideration of the material strength degradation due to the elevated temperature.

Dec 1, 2022

By Chee S. Theng

As the 2015 president of the Society for Mining, Metallurgy & Exploration Inc., I am pleased to present the 2015 issue of the Transactions of the Society for Mining, Metallurgy & Exploration Inc., Vol. 338. 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 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 2015 Transactions contains some of the most interesting research and insights from the past year and features an international slate of authors spanning industry, academia and government. Papers include the latest findings from the U.S. National Institute for Occupational Safety and Health (NIOSH) and special-focus articles on gold processing, iron ore processing and coal processing. The 2015 Transactions consists of a total of 67 technical papers, encompassing all 22 papers published in 2015 in the Technical Papers Section of Mining Engineering (Vol. 67) and all 29 papers published in 2015 in Minerals & Metallurgical Processing (Vol. 32). Additionally, this volume contains 15 papers and one discussion 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 2015 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.

Jan 1, 2015