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By A. M. Gaudin

At the 1971 Annual Meeting we presented a paper on the results s obtained by wet magnetic separation on very fine, slightly magnetic material . Considerable interest was shown in a corollary subject, namely; on the type of magnetic con¬struction of the Magnetic Engineering Associates (MEA) high-intensity magnetic separator (HIMS). it is the purpose of this paper to describe the principles of this separator and to give answers to many of the questions directed at us both in session and privately since the March 1971 meeting of the AIME. It is well-known that passage of a direct electric current through a wire shaped in the form of a loop results in a magnetic field being created in the volume enclosed within the loop. The magnetic field is proportional to the amperes of electric current passing through the wire. If the wire is in the form of a solenoid consisting of 11 turns, the magnetic field is n times larger. Hence the expression ampere-turns commonly associated with magnetic separators. If a particle, free to rotate and of higher magnetic susceptibility than the medium, is placed in a magnetic field, it will orient itself within that field, and it will move within the field in such a way as to go into a more intense part of the field. The traction on the particle is proportional to its inherent magnetic property which depends on its magnetic susceptibility and its volume, to the mag¬nitude of the field at the spot where the particle is situated, and to the magnitude of the field gradient at that spot. Of the three factors that control traction on a particle in a magnetic field, the magnet designer can effectively control two, the magnetic field and the field gradient. In a wet magnetic separator such as the HIMS magnetic separator, there is another force exerting traction on the particle, and that is the force of the fluid (liquid) on the particle. It is, therefore, essential to examine the relationship of the fluid to the magnetic field. First, assume the water in which magnetic and non-magnetic particles are suspended to be stagnant. In the absence of magnetic field, the only forces acting on the particles are those due to gravitation on the particles and on the fluid displaced. This is the subject, so important in gravity concentration, discussed in elementary texts of mineral engineering'.

Jan 1, 1972

By N. T. Cowper

Slurry viscosity ultimately affects the majority of mineral extraction processes. However, to date its role has been disguised because mineral processing equipment has been conservatively designed to operate at minimal slurry viscosity. With most ores this still meant acceptable solids concentration was achieved. However, with the advent of treatment of weathered ores the resulting higher slurry viscosity (rheology) has meant solids concentration has had to be reduced, often to unacceptable levels. To permit operation at higher solids concentration chemical dispersants are employed. These dispersants are expensive and their addition should be controlled. Slurry Systems Pty Limited (SSPL) has developed an On-Line Viscometer to monitor and control slurry viscosity, whether by controlling water addition or by controlling dispersant addition. Using this instrument the slurry rheology can be controlled at the optimum level, maximizing solids throughput, and minimizing water, reagent, and dispersant addition. This paper discusses rheology of typical mineral slurries, the relationship between slurry rheology and percent solids in a slurry, and the need for rheological control in mineral processing. The effects of rheology on various process steps, and the use of dispersants are reviewed. The paper concludes with summarizing actual case histories and cost impact of Theological control.

Jan 1, 1992

By Cory Bolen, Nadav Bar-Yaakov, Eric Zimmerman, Gregory Raines

The Chimney Hollow Reservoir Project broke ground in August 2021, constructing the tallest Asphalt Core Dam in North America, intending to improve reliability of drinking water supply to Northern Colorado communities. Aiming to expedite and streamline the geological mapping process in the tunnel, Stantec’s teams have developed a mobile and web-based GIS application for digital mapping input and rock mass evaluation, allowing real time decision making for assigning tunnel support class and resulting in a faster more efficient process. The following article presents and demonstrates the GIS mobile and web application-based process, the mapping results and review additional uses of the database created.

Jun 13, 2023

By Samuel W. Woods

The Tacoma, Washington plant is one of six plants in the United States Gypsum Company's Acoustical and Mineral Fiber Division. The Tacoma facility was acquired in 1959 along with six other mineral wool plants from the American Rock Wool Company. Originally, the Tacoma plant was built as a carbide plant during the Second World War and after that was converted and operated as a mineral wool plant by several insulation companies. Through these early years, the use of raw materials at Tacoma consisted primarily of slags along with small percentages and various combinations of silica (in various forms such as gravel), limestone and basalt. These raw materials were melted in cupolas using coke as the heat source. Raw material usage and types as well as mineral wool production methods and equipment remained without major changes for many years.

Jan 1, 1983

By W. N. McAnulty

Because so many interrelated technical, economic, legal and political factors are involved in evaluation of commercial mineral deposits, it is common practice today to assign such work to a team of specialists including geologists, mining engineers, metallurgists, lawyers, and economic evaluation experts. Each member of the team plays an important role; the role of the geologist is particularly important. The geologist involved with evaluation of fluorspar deposits needs all the geologic and economic training and experience required for evaluation of metallic mineral deposits. Few, if any, industrial or metallic minerals occur in so many geologic environments as fluorite. Fluorspar, and aggregate of rock and mineral matter containing enough fluorite to make a commercial deposit (ore), is somewhat more limited in its modes of occurrence than fluorite, but it too is found in a variety of environments.

Jan 1, 1970

By R. W. Draves

Planning and testing in advance of the mining operation are essential. This advance work can involve physical and chemical analysis of overburden cores, field test plots, green- house studies or any of a multitude of other baseline data collection activities. This paper presents the results of Central and South West's field test plots and how they relate to topsoil substitution. Besides the obvious need for testing in advance of mining, there are the inevitable regulatory requirements. Quoting from the office of Surface Mining Regulations concerning topsoil substitution: 216.22(e) TOPSOIL SUBSTITUTE AND SUPPLEMENTS -Selected overburden materials may be substituted for or used as a supplement to topsoil if the office determines that the resulting soil medium is equal to or more suitable for sustaining revegetation than is the available topsoil and the substitute material is the best available to support revegetation.

Jan 1, 1985

Mill #4 processes mildly refractory ore from Carlin Trend deposits. Diagnostic analysis of plant operating data was used to generate a mathematical model containing the key parameters influencing the gold recovery. The model was used to direct modifications to plant operating practice. The cyanide dosing strategy was changed to reduce preg-rob gold masses and cut reagent consumption A finer grind was achieved without capital investment. The density in CIL was lowered, and tighter control was exercised over plant throughput. These changes resulted in a recovery increase of at least 2%, worth $111,000/month at $300/oz, and concomitant reagent cost savings of $55,000/month.

Jan 1, 1999

By Jon J. Kellar

The adsorption of oleate at the surface of a fluorite single-crystal internal reflection element has been investigated using Fourier transform infra-red/internal reflection spectroscopy (FTIR/IRS). The application of this innovative experimental technique has added a new dimension to the investigation and understanding of collector adsorption phenomena. It is now possible, for the first time, to measure in-situ and in real time the adsorption density and bonding nature of collector species adsorbed at mineral surfaces. In this regard, oleate adsorption densities were calculated from spectral data, and the equilibrium adsorption isotherms were found to agree quite well with other adsorption isotherms reported in the literature. At low equilibrium oleate concentrations(<10-5 M), monolayer-type cover-age was observed in the chemisorbed region. It was found that in this region the adsorption density increases with an increase in temperature, which sup-ports experimental results from previous ex-situ FTIR studies and thermochemical studies in which it was shown that the chemisorption reaction was endothermic. At higher equilibrium oleate concentrations (>10-5 M), the adsorption density increases dramatically at the point of surface precipitation. The oleate adsorbed in the chemisorbed region has a distinctly different spectrum than the oleate adsorbed in the surface precipitation region of the adsorption isotherm. In the chemisorbed region, the oleate appears to be mono-coordinated at the fluorite surface.

Jan 1, 1989

By J. W. Oberholzer

This paper describes research being undertaken by the Chamber of Mines Research Organization (COMRO) which is designed to assist the continuous miner operator and section foreman in the performance of their jobs. The project will initially provide visual assistance to the miner operator, and later will semi-automate the mining (cutting) process. Using a technique known as "RF tagging," the project will also provide real-time or near-real-time information about the performance of the loading and hauling units to the section foreman, allowing him to quickly detect problems and take action where appropriate. The project is based upon the application of currently available technology, and the first phase is scheduled for in-mine testing within the next year.

Jan 1, 1991

By R. R. Godard

The practice of dust abatement or control is not new to any operation of United States Steel Corporation. This report will review those activities, past and present, within the five operating districts of United States Steel-Coal Operations with specific reference to mechanical and continuous mining, and including both the health and safety aspects of the problem. Obviously, the first principle of dust control is to inhibit its formation If this is not practical, steps may be taken to prevent its becoming airborne. Airborne dust control can be realized by either collecting it at the point of generation, diluting it with large volumes of air to reduce concentration, settling it by various means, or with reference to ignition hazard only, render it incombustible by neutralization with an inert material. These basic principles have been verified by the work of many, including the Bureau of Mines, U. S. Department of Interior, Bituminous Coal Research, Inc., and the Mining Research Establishment of the National Coal Board of Great Britain. Their application to every day mining problems is best illustrated by the following examples.

Jan 1, 1967

By W. Szymanski

The United States contains one of the world&apos;s largest reserves of uranium. Domestic production and exploration activities, however, have declined since the early 1980s due to weaker-than-expected growth in nuclear power demand and to foreign competition. The main result has been that more costly and less productive conventional mines and mills have closed. Meanwhile, industry productivity as measured by uranium output per employee has increased threefold since 1980. At the end of 1992, only six plants, all nonconventional, were operating in the United States. Due to cost considerations and increased environmental awareness, any additions to existing capacity are expected to be met through nonconventional in situ leach plants.

Jan 1, 1994

By Robert W. Wheeler, Richard G. Ames, Robert B. Reger

Introduction The use of diesel engines as an alternate power source in US underground coal mines has been a controversial step towards more efficent mining practices. Three areas of potential benefit are foreseen. First, diesel-powered mining equipment is believed to be more efficient, resulting in less occupational risk for any given amount of production. Second, diesels are believed to pose fewer intrinsic hazards, especially those related to fires and ignition of combustibles. Finally, several other health and safety advantages are foreseen for diesel units. Each of these issues will be discussed separately. Diesel Efficiency Proponents of the use of underground diesel-powered mining equipment point to increased production efficiency due to greater maneuverability, speed, power, and payload (Bradbury, 1973; Jorgensen, 1982; Ogden, 1978; Wenberg, 1979; Olsen, 1980). Units most suitable for diesel power include LHD vehicles, shuttle cars, personnel carriers, and maintenance vehicles. Estimates of increased efficiency vary from 60%-300% and more (Wenberg, 1979). Increased diesel mining efficiency is usually viewed as making it practical to mine lower grade seams. Diesel units can also operate over a wider range of floor pitches and distances than electrically-powered units, thus allowing mining of seams with special mining problems (Olsen, 1980). Diesel application is not a universal substitute for electrical power. For example, continuous miners are unlikely diesel candidates. Reduced Intrinsic Hazards Proponents of diesel use have pointed to the increased safety potential due to a reduction in electrocutions, arcs, burns, underground cable fires, and methane ignition (Ogden, 1978). Diesel units are frequently employed in maintenance activities for lifting and moving, and for coal cleanup. Thus the case is made that diesel use, by making powered operations more conveniently available, reduces the incidence of lower back injuries and related causes for days lost due to disability (Olsen, 1980). Several other issues relating to diesel safety have also been suggested. Diesel units can continue operation even during power outages allowing, for example, personnel evacuation. The maneuverability of diesel units make them particularly attractive in difficult physical conditions, such as long haulage from the face to the belt and in areas where water is deep. The case for diesel use focuses heavily on the potential for a "per worker" reduction in accidents, or a reduction in the severity of accidents. Since accidents are a major part of the health impact of mining, a reduction in accidents and resulting injuries would make a major contribution to the health of coal miners. Opposition to Diesel Use Opposition to the use of underground diesel mining equipment in the US seems to have started with the United Mine Workers of America. Some opposition to US diesel use has been based on a widely publicized 1976 letter from NIOSH to Mine Enforcement and Safety Administration administrator Robert Barrett (NIOSH, 1982). In essence, this letter warned that while insufficient evidence existed as to diesel effects on underground coal miners, NIOSH had concerns based on prior knowledge of separate diesel exhaust constituents and the potential for interaction between these constituents and coal mine dust. Current opposition to underground diesel use has focused on respiratory health effects related to diesel emissions, particularly nitrogen dioxide (NO,), carbon monoxide (CO), and particulate content (Barrett, 1982). Through

Jan 4, 1983

By Edgar T. Gregory

A quiet revolution has taken place in the conveyor belt industry, Man-made materials, improved production facilities, better splicing techniques and emphasis on repair and maintenance have all contributed substantially to lowering material handling costs for the mining industry, It wasn&apos;t too many years ago that the rubber industry had only cotton for a belt carcass and tree grown rubber for the protective cover. Then came the development of monofilament rayon. This material had desirable elongation and elastic properties and was the first synthetic fiber to be used in place of cotton. But wet strength and other limitations restricted its use, and the conveyor belt industry turned to nylon. Initially, nylon was considered suitable only for the cross threads or filler threads of a belt carcass. Then technical advancements in heat setting and fabric weave created a major change in belt construction. As a result of these advances the industry was able to take advantage of the full tension strength of nylon cord. Another breakthrough in the use of synthetics was the tremendous increase in adhesion resulting from a chemical bond, rather than the limited physical bond available with cotton. But the advantages of nylon had a more Car-reaching effect, We were able to design a two-ply nylon belt that did the work of a four- or five-ply cotton or rayon belt. A six-ply nylon belt now replaces a twelve-ply cotton elevator belt. Arid nylon resists moisture, acid and mildew, It also has excellent resistance to impact and can be produced with controlled elongation and elastic properties that work to great advantage in reduced-ply belt constructions.

Jan 1, 1971

By Naohiro Kurokawa

Isa Limestone Quarry with an annual production capacity of 18 million metric tons is known as the largest limestone deposit in Japan located in the mountainous region about 20 mile northwest of Ube City, Yamaguchi Prefecture, Japan adjacent to Isa Cement Factory to which it belongs, and which constitutes a mainstay of Ube Industries? cement operating division. Isa Cement Factory is equipped with a N.S.P. kiln of capacity of 3 million metric tons per year, which is the largest of its type in the world. Geographically, it is situated in the south- western tip of the Mainland of Japan (Mid City, Yamaguchi Prefecture) and is bordered by the scenic Akiyoshi Karstic Plateau which is world famous for its huge stalactite grotto.

Jan 1, 1982

By J. E. Murphy, Y. Topkaya, R. E. Johnson, B. R. Palmer, D. K. Dysinger, R. B. Bhappu, A. E. Clark

The U.S. Bureau of Mines utilized a central composite experimental design to investigate leaching kinetics of pure chalcopyrite in the sulfuric acid-oxygen system. The six factors studied were oxygen pressures of 150, 300 and 450 PSI, leach temperatures of 35O, 65O, and 95O C, oxygen-to-chalcopyrite mass ratios of 0.5, 1.0 and 1.5, leach times of 8, 16 and 24 hours, initial acid strengths of 0.6, 1.2 and 1.8 g H,SO,/g chalcopyrite and pyrite to chalcopyrite mass ratios of 0, 1, and 2. Chemical analysis and oxygen consumption measurements indicatedthat leaching occurs through three consecutive reactions. Temperature was the primary determinant of leach rate and solution acidity was the primary determinant of oxygen consumption, sulfur oxidation, and activation energy.

Jan 1, 1993

By G. A. Weisenfluh

The successful application of factors limiting the? availability of coal in eastern Kentucky depends on ac-curate assessment of the original resources. Examination of several previous coal-resource estimates for the region reveals significant differences among the outcomes. These differences relate to methods of analysis, biases in data and their utilization, and the problem of defining the lateral continuity of mineable beds. Improvements in the methods of estimating the original resources would greatly enhance the reliability of the results of the Coal Availability Program.

Jan 1, 1995

By Kirk Carlton

This paper deals with a group of subjects so familiar to all of us that we might question the need for discussion. Even so, nearly every day&apos;s business turns up expensive examples of differences in understanding, misdirected assumptions and incomplete technical purchase documents. As our international activities increase, so do these problem areas. Their expense in both money and embarrassment gives rise to this attempt to focus a little extra attention on technical criteria and specifications. The two terms ?criteria? and "specifications" are, we believe, worth separating with respect to meaning. They should not be used interchangeably, although they often are. Criteria are by definition "standards for judging", whereas specifications are "enumerations of particulars". In relation to plant or project engineering, the criteria are the general rules and data which apply to the whole project and the specifications are the further listing of detailed requirements for specific contractual items or pieces of equipment. We&apos;ll look a little more closely at specifications after we give another minute or two to this "criteria" subject,

Jan 1, 1973

By E. E. Jones

The lignites of Arkansas, Louisiana and Texas are typically described as muitiseam deposits which contain quantities of day and sand in thin lenses or in admixture with the fuel itself. These materials are often included in the run-of-mine fuel and can have very adverse effects in the end use. Since May of 1982 the Dow Chemical Co. has operated a pilot plant for the beneficiation of lignites. This facility has successfully removed sand, clays and petrified wood from the lignite producing a fuel comparable to or better than the selectively harvested run-of-mine materials. The design, operation and results from this plant were presented by J. H. Everitt at the 1984 Coal Technology Conference.

Jan 1, 1986

By E. D. Hummer

During the planning phase of the fine coal cleaning addition at the Gary Coal Preparation Plant, careful consideration was directed toward the problem of minus 48 mesh refuse disposal. The plant flow sheet included wet screening the raw coal at 1/4 inch, pumping the minus 1/4 inch raw coal to bowl desiltors for desliming, and then cleaning the disliked raw coal on tables. The material to be removed from the circuit as minus 48 mesh refuse consisted of the minus 100 mesh desiltor overflow thickened in two 120 foot diameter thickeners and minus 1 mm screened from the table refuse. Later a flotation plant was added to recover coal from the desiltor overflow, and a classifier replaced the screens to make a sharper size separation of the table refuse at 48 mesh Today the minus 48 mesh refuse at Gary consists of thickened flotation tailings and thickened spiral classifier overflow. The transportation of large quantities of fine wet refuse filter cake mixed with jig and table refuse over existing conveying equipment would have been neither dependable nor economical. Filtration was therefore impractical, and disposal of the fine materials was a problem. The decision was to pump the material to storage ponds

Jan 1, 1965

By C. D. Keith

Erie Mining Company, a pioneer in the iron ore pelletizing industry, has continued to develop methods and equipment to improve cost and quality. Under the management of Pickands Mather & Co., this property, owned by Bethlehem Steel Corporation, Youngstown Sheet and Tube Company, Steel Company of Canada, Ltd., and Interlake, Inc., has initiated a number of operating improvements for the taconite industry. One of the most noteworthy of these, which is applicable to the entire mineral industry, is the principle of fine screening with rappers (FSR). Erie&apos;s original efforts in the field of fine screening, which date back to 1961, were described in the April 1967 issue of the MINING ENGINEERING magazine. In that same month, Erie placed into operation a full scale PSR and regrind plant addition, capable of processing 10.3 million long tons of iron ore concentrates, produced by conventional taconite grinding, classification, and magnetic separation methods. Since this first successful commercial operation of the PSR principle et Erie, it has been applied in eight other iron ore beneficiation plants end is being tested by other U.S. and foreign companies. In addition to the use of PSR units at Erie Mining Company, Pickands Mather has applied PSR to other of its managed properties end to projects under development. This paper covers these applications as well as a now application at Erie Mining Company.

Jan 1, 1971