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By C. Flores

It is well known that manganiferous silver ores containing manganese intimately associated with silver are not amenable to conventional extraction methods. The segregation process has been applied primarily for recovering copper from oxidized and oxide-sulfide ores. A new alternative process combining segregation roasting followed by flotation to recover silver from refractory manganiferous silver ores, was studied using a 23 factorial experimental design. Laboratory investigations have been conducted on a manganiferous silver ore analyzing 0.02% copper, 0.09% lead, 0.33% zinc, 12.55% manganese and 187 g/ton silver to study the effects of additives salt, coke and copper oxide on silver recovery. Results indicate that 79.3% silver recovery can be attained in the absence of copper oxide and 88.4% when the copper oxide content is 1.5% at '750°C, 2% salt and 1% coke and 30 minutes of roasting time. It was concluded that doping with copper oxide improves silver recovery.

Jan 1, 1994

By B. A. Wills

With the increasing need to mine lower grade ores, high energy-related costs in comminution are of major concern. Very fine grinding is needed to liberate the very fine mineral particles in these ores. Not only is this expensive but it leads to greater losses in 'slimes'. In the early 1970's, 50% of the tin mined in Bolivia, 30% of the phosphate mined in Florida and 20% of the world's tungsten were lost in this way (Somasundaran, 1979). Gravity concentration techniques become unacceptably inefficient for particle treatment below 25-50µm, and even flotation fails in the ultra-fine range. Two approaches can be adopted to try to overcome this problem. The first involves increasing the efficiency of existing equipment or developing new slimes treatment processes. Gravity devices such as the Bartles-Mozley concentrator have been developed for this purpose and good recovery has been reported from 100µm down to 5µm. Such machines, however, have relatively low throughputs, so that large areas of plant space are generally required. Flotation is rapidly growing in importance for the treatment of ultra-fine minerals traditionally treated by gravity concentration.

Jan 1, 1986

By K. Dagdelen

The definition and shortcomings of traditional cutoff grades are discussed. The concept of optimum cutoff grade policy which maximizes the Net Present Value (NPV) of annual cash flows coming from a mining project is introduced within the basic framework outlined by K. F. Lane. Several examples are used to demonstrate the shortfalls of cutoff grade policies obtained by various heuristic optimization techniques. An algorithm to obtain an optimum cutoff grade policy which maximizes the NPV of a project is given and described in detail.

Jan 1, 1993

By William G. Pariseau

The purpose of this paper is to present a discussion of the various approaches that can be utilized in the study of mine subsidence phenomena. Attention is focused upon the rational selection and use of laboratory models. Broadly interpreted, mine subsidence is the deformation of the rock mass enclosing the mine. Depending upon a number of factors, the movement of the subsiding rock mass may be such as to disrupt gas and water lines or other buried utilities, to damage surface structures such as buildings and bridges, to dislocate streams, roads, and rail lines, to aggravate acid mine drainage and fire problems, and to generally mar the landscape. It is clearly a problem that no mine manager can safely ignore. It is also a problem that will grow with the general population increase. In the following, a summary review of past and present approaches to subsidence studies is given. The possibilities of duplicating subsidence phenomena in laboratory models are examined, and an analysis of a particular type of model is presented. Some preliminary results obtained from a model of the particular type analyzed are then discussed.

Jan 1, 1968

By M. E. Grimes

The Port Radium mine of Eldorado Mining and Refining Limited, located on Great Bear Lake only a few miles from the Arctic Circle in north-western Canada, is the oldest uranium producer in Canada, The first concentrates were produced in 1933 and except for a period between 1940 and 1942 the mill has operated continuously. Although it is located in a remote area, and compared to more recent mines in other areas is a small tonnage operation, nonetheless the relatively high grade of the Port Radium ore has permitted operation to date on an economical basis. The mill process at Port Radium includes the original gravity concentration mill, and since 1952 an acid leaching plant which treats tailings from the gravity mill and tailings recovered by dredging of residues from underwater dumps in Great Bear Lake. The pregnant solution from the leach plant has to date been processed through aluminum reduction to yield an intermediate grade uranous phosphate-arsenate precipitate, Because of the rising costs of the aluminum reduction process, and its sensitivity to ore composition, Eldorado became interested in possible application to Port Radium of the solvent extraction processes of which we were obtaining increasing information in the latter part of 1954 and during 1955.

Jan 1, 1958

By M. C. Roberts

The material composition of product is defined as the quantity of metal used per unit of product manufactured during a year. This ratio measures the efficiency of converting a ray material into final products. The material composition of product has shown steady and persistent declines over time for most metals and materials. This tendency demonstrates the continued improvements in manufacturing technology, resulting from substitutions of other materials and improvements in production efficiency. The purpose of this paper is to study trends in the material composition of product to reveal the impact of advanced materials on the use of traditional metals.

Jan 1, 1990

By K. R. Griffin, K. D. Luxbacher, E. C. Jong

The schlieren technique describes an optical analysis method designed to enhance light distortions caused by air movement. The ability to visualize air flow has significant implications for analyzing underground mine ventilation systems, including the enhancement of surveys and models. Currently, traditional schlieren methods are impractical underground. Background-oriented schlieren (BOS) provides a solution to this problem. BOS requires two primary components, a professional quality digital camera and a schlieren background. A schlieren background is composed of a varying contrast repetitive pattern, such as black and white stripes. This background allows the camera’s sensor to capture minor light diffractions, such as those caused by air flow. Although BOS shows great potential for ventilation analysis, sensitivity is an issue. This paper seeks to validate the BOS technique for imaging flow through a regulator by comparing BOS images with traditional schlieren images. This paper also outlines initial experimental efforts used for the validation.

Jan 1, 2011

By P. T. Bissert, D. S. Yantek, L. Yan, M. D. Klein

Federal regulations require that refuge alternatives (RAs) be located within 305 m (1,000 ft) of the working face and spaced at one-hour travel distances in the outby area in underground coal mines, in the event that miners cannot escape during a disaster. The Mine Safety and Health Administration mandates that RAs provide safe shelter and livable conditions for a minimum of 96 hours while maintaining the apparent temperature below 35 °C (95 °F). The U.S. National Institute for Occupational Safety and Health used a validated thermal simulation model to examine the mechanisms of heat loss from an RA to the ambient mine and the effect of mine strata composition on the final internal dry bulb temperature (DBT) for a mobile tent-type RA. The results of these studies show that 51 percent of the heat loss from the RA to the ambient mine is due to radiation and 31 percent to conduction. Three mine width and height configurations and four mine strata compositions were examined. The final DBT inside the RA after 96 hours varied by less than 1 °C (1.8 °F) for the three mine width/height configurations and by less than 2 °C (3.6 °F) for the four mine strata compositions.

Jan 1, 2016

By Joseph M. Driscoll

After 30 years of successfully mining gold, Newmont Gold has temporarily ceased production from the original Carlin Pit. In late 1993, the Carlin East decline was driven and an extensive underground exploration program was started. Today, Newmont Gold produces refractory ore from the Carlin East Underground at the rate of 864 t/d (950 stpd). Annual production is more than 3.1 t (100,000 02). More than 70 underground miners will be employed during Carlin East's estimated six-year mine life. About 70% of the ore at Carlin East is mined by mechanized longhole stoping with delayed, cemented backfill. The remaining ore is mined by underhand drift and cemented fill methods.

Jan 1, 1997

By Victoria Vaccarezza, Corby Anderson

The demand for rare earth elements for everyday technology and applications has initiated much research into the extraction and recovery of these rare earth elements. An otherwise unknown group of minerals, eudialyte is a zircon silicate consisting of rare earth oxides (REO), contained in a unique mineral structure and represented by a complex chemical formula. Research into extraction and recovery of rare earth elements involves various beneficiation and hydrometallurgical techniques. The goal of beneficiation being to efficiently liberate and upgrade the REO content, followed by hydrometallurgy to extract the desired elements. This overview will discuss previous research on treating eudialyte group minerals via different mineral processing and extraction techniques.

By Sue Sawyer

In October, November and December, teachers at the National Science Teachers' Association (NSTA) area conventions were lured to visit the Minerals Education Coalition (MEC) booth by the promise of free rocks, video tapes, and literature on earth science topics. Teachers were content to stand in lines that at times took as much as an hour and a half to progress through the exhibit. Adding to their interest was the opportunity to converse with people from the minerals industry who were staffing the booth. The MEC was formed by a group of associations and companies in the minerals industry. They felt the need to educate the public about the current-day minerals industry and how it affects everyone's life. The American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. (AIME) underwrote the major expenses of exhibit space and exhibitor services at all three conventions in 1997. SME members have been active in staffing and chairing the NSTA exhibit booth. But they represented only about one-third of the volunteers for the booth. Additional volunteers were drawn from local minerals companies, associations, interested teachers and other support groups. (See donors list on page 64.) In 1997, the conventions were held in Pittsburgh, PA, Denver, CO and Nashville, TN. The local SME GEM Committees chaired Pittsburgh and Denver and The Rogers Group Inc. supplied the chairperson in Nashville. Each exhibit relies on a local committee to plan and run the booth. Support is available from the GEM Projects Coordinator at SME headquarters. Usually the chair of the committee is drawn from the local SME membership. It is easy to see why the MEC booth is so popular. Free literature, videos, posters, workshop packets and rock specimens were handed out to about 5,500 science teachers at the three sites. Feedback from the attending teachers was overwhelmingly positive: "Who do we thank for these great materials?" Some of those great materials included Caterpillar's outstanding donation of Common Ground videos and teacher packets for Pittsburgh, Denver and Nashville for every teacher expected to attend. Placer Dome sent enough What's a Mine coloring books and It Comes from a Mine activity books for teachers at all three sites. Newmont supplied all teachers with an excellent poster describing gold processing. Women in Mining Education Foundation had plenty of its classroom activity handouts. The American Coal Foundation provided a list of its educational materials that are given out free to teachers who request them on school letterhead. The National Mining Association had its Facts About Minerals and Facts About Coal available. US Borax provided the funding to reproduce the NMA black and white posters that were published as inserts in Mining Voice magazine. In addition, each site had other materials chosen by the local committees to round out their selections. At each exhibit site, committees raise between $8,000 and $12,000 in cash donations from industry to support the high overhead of producing this exhibit. Usually, there are between 12 and 18 different rock specimens representing a range of mineral ores from aggregates to the metal ores. The committee arranged to have these donated (along with the freight charges to ship them to the site). Literature is also donated by the industry. It covers a diverse spectrum from basic information on rocks and minerals to posters, flow charts, videos and coloring books. Other donations include storage space before the event, haulage of items to the hall and door prizes. These exhibits could not have been staged without the network of SME Local Sections and the able chairs and committees at each site. At this time, credit should be given to their extensive donation of time and effort.

Jan 1, 1998

By John C. Ferm

The role of geology in coal exploration, mine planning and mine development has, in the past, been relatively small. The primary reason for this lies in. the simplicity of geologic concepts that were necessary to bring these operations about. These concepts can be briefly stated as follows: 1) coal occurs in the beds or layers and is overlain and underlain by shales, sandstone or limestone in varying porportions, 2) each coal bed has been given a name and certain quality characteristics can often be associated with a named bed and 3) coal beds (and their adjoining rocks) are often folded into broad anticlines or synclines and, in some places, displaced or faulted. In actual practice, however, these simple principles have been found wanting. Thickening, thinning, pinch outs or changes in coal quality occurred but the occurrence was apparently unpredictable and the only real solution to such problems seemed to be practice and experience. This combined with ingeneous engineering solutions have provided answers to most questions. Perhaps a more fundamental reason that geology could offer so little input to coal mining is that the thickest, most persistant and best quality coal seams followed the above stated rules fairly well. In many areas, however, such seams are now nearing exhaustion and the increased demand for clean, non-polluting, safe energy is quickly bringing a need for techniques of exploration and mining procedures that will make development of formerly unminable seams a profitable venture. For the past 20 years some considerable body of knowledge has been added to the framework of the geology of sedimentary rocks and it is the purpose of this paper to present some of these newer ideas that will be useful in solving some of the present problems of coal exploration and development.

Jan 1, 1976

By R. E. Thill

An ultrasonic, pulse-immersion apparatus and method are described for determining the effects of moisture on the dynamic elastic properties of rock. The method provides an alternative approach for assessing the moisture sensitivity of rocks. Ultrasonic wave velocities are continuously monitored in immersed rock samples as a function of water absorption and time up to saturation. Moisture effects on compressional wave velocity vary as a function of the type of rock and the time and amount of water absorption. Regression analyses are used to curve-fit plots of the data and to derive empirical expressions for compressional wave velocity as a function of water content for different categories of rock. Results indicate that compressional wave velocity can be used to predict both the moisture content and its effect on strength and deformational properties of rock. These results have potential for detecting or monitoring bad roof conditions in situations where the mine rock exhibits strength degradation with moisture absorption.

Jan 1, 1986

By H. Lawrence

In 1977, the Bureau of Mines awarded a grant to the State of South Carolina to explore the possibility of using Landsat multispectral scanner (MSS) data as an aid in monitoring surface mining activities in selected counties of the State. Work had been done in Aiken County prior to the grant by Bureau of Mines and State personnel at the EROS Data Center using both the GE Image 100 and ESL IDIMS systems. The initial work on the 1-100 consisted of locating and measuring the areas of various kaolin mines. The results were excellent on location, identification, and accurate area measurements of several mines as compared with aerial photos of each mine. The effort also included locating and measuring the size of all mines (including sand and gravel) within two U.S. Geological Survey (USGS) 7 ½ min quadrangle maps. Line printer overlays using the IDIMS equipment and software resulted in the location of all known mines within an estimated error less than ±91.4m (5300 feet). Mine acreage was calculated by counting each symbol (which represented one pixel) and multiplying by 1.1 (the number of acres per pixel). Figure 1 shows a portion of one quadrangle overlay. Table I gives a comparison of acreage measured for sever- al mines from the 1-100 and IDIMS systems vs. aerial photo measurements.

Jan 1, 1979

By J. P. McCluskey

The effects of air quality regulations passed in the last few years have been felt in a more pervasive way by the electric utility industry than by perhaps any other industry. I'm referring especially to those regulations dealing with the control of air emissions from stationary sources, and those specifying the quality of fuel used. Particularly, I would like to describe some of the effects that these regulations have had on the Commonwealth Edison Company. To put the subject into perspective, a brief descrip¬tion of the company will be presented first. Then, a historical outline of some of the efforts at control of electric generating station emissions will be described. Following this will be an indication of the Company's response to early State and local regulations prompted by the growing pressure for stringent envi¬ronmental control. Finally, the Company's plans to achieve com¬pliance with the most recent, Federally approved, State of Illinois regulations will be summarized.

Jan 1, 1973

By C. H. Pitt

A jet slurry apparatus has been constructed to test corrosive/erosive wear properties of grinding ball metal. Plain high carbon steel heat treated to a hardness of about 60 RC was used. Slurries of quartz and chalcopyrite ore concentrate were used as the jetting media. Weight loss due to pure corrosion was determined by the linear polarization technique and weight loss due to pure erosion was determined by jetting while cathodically protecting the sample. By comparing the total weight loss with the sum of the weight losses from pure corrosion and pure errosion it was found that there was a synergistic effect between corrosion and erosive wear. Erosive wear rates are given as a function of pH and mineral type.

Jan 1, 1984

By M. Adnan Goksel

A blast furnace test of approximately 5,000 tons of PelleTech Corporation (PTC) cold bond pellets was successfully run at Kaiser Steel Corporation (Kaiser) Steel Manufacturing Division at Fontana, California. The pellets were produced from mill scale, BOF dust and blast furnace flue dust. A 15 day base period, during which time the metallic burden was 2/3 heat indurated pellets and 1/3 sinter, preceeded the test. During the test period the metallic bur- den was 10% cold bond pellets, 56.7% heat indurated pellets and 33.3% sinter. A 15 day post test base period followed during which the PTC pellets were replaced by conventional pellets. The pellets were produced in the 3.C Semi-works Facility located on Kaiser property. The facility incorporates the Michigan Technological University Hydro-Thermal Agglomerating Process.

Jan 1, 1979

By Allen D. Graham

The coal industry in South Africa is briefly outlined. Test- work carried out on bulk samples of coal in the laboratory and used in the design of the Van Dyks Drift washery are described. Factors affecting the selection of equipment and the designed capacity of the plant are discussed. A description of the crushing plant, washery and load out section is given together with performance data obtained in the final acceptance tests. New features incorporated in the Van Dyks Drift plant and in more recent plants of the Group are outlined.

Jan 1, 1982

By Ping Zhang, Shahram Mozaffari, Andreas Ylmefors

The risk associated with mining induced seismicity and the related rock bursts has become one of the major threats to the safety and sustainability of mining at the Kiirunavaara mine. The causes of mining induced seismicity at the Kiirunavaara mine are very complex and have affected our understanding on the source mechanisms of seismicity and further the mitigation of the seismic risk. Detailed analysis of historical mining induced seismicity at the Kiirunavaara mine was conducted. The focus of this analysis was placed on the classification of large seismic events and the evaluation of the influential factors on the classified seismic events. 145 events with local magnitude larger than 1.5 that occurred between January 1, 2011 and March 31, 2021 were analyzed. For this analysis, seismic events located in the hanging wall were not included, as these have not been observed to cause large damages to the mine itself. It was found that the magnitude of the events had good correlation with the stress change in relation to the production location. The seismic events were classified as mining-front associated, ore-pass associated, mining-front and ore-pass associated and others, according to their hypocenter location. Most of the mining-front associated events, concentrated around the production levels and slightly above and below them, generally correlated with shear cracks, and most of them occurred when the ore flow between two production levels started. The numerical modelling showed that slip of the geological discontinuity, due to unclamping between hanging wall and footwall, could be the major causative mechanisms, which further supports this finding. The ore-pass associated events are located close to the ore passes. Large seismic events located between ore passes have the source mechanism of both fault-slip and non-shear, but events located at the outer side of ore passes were all fault-slip type. By checking with the ore pass scanning data, it was concluded that the most of the events located between ore passes could be pillar bursts. An elastic core concept has been then used to define a critical pillar width. The paper is not intended to be prescriptive but rather to initiate discussion of the possible classification of seismic events at the Kiirunavaara mine and to present new perspectives of the causes of the seismicity for improving the present seismic risk management.

Apr 26, 2022

By H. Colijn

The problem of the freezing of moist raw materials, such as concentrates, in railroad cars during winter shipment has been a continuing source of both economic and operational trouble to the industry and to the railroad companies. The difficulties center around the discharging of frozen cargoes into the plant materials handling system. Because of cargo freezing, appreciable delays in car-dumping schedules occur each winter and cause additional expense for demurrage charges and for slowdown of plant operations. In one plant during one winter, a car dumper rated at 40 cars per day could dump only 3 cars per day in bad weather. Delays became so serious one winter, that 500 cars held in the yard became so badly frozen, that they were sent to the southern part of the United States to thaw after they accumulated an average of two months demurrage charges. These delays in car unloading become critical if unit or integral train concept is applied to the movement of raw materials. Anticipated savings in transportation costs through better equipment utilization are largely based on rapid loading and unloading cycles of whole trainloads. If freezing problems cannot be adequately solved, unit train operations cannot be operated to achieve the potentially large reductions in transportation costs. The freezing problem may tend to become even greater in the years ahead, because the unit train concept will allow the trains to run faster and consequently the heat loss will be accelerated due to the larger heat transfer coefficient. A compensating factor, however, will be the shorter travel time. Further, the sources of raw materials being mined are located farther north than before and the ambient temperatures during transit are going to be lower.

Jan 1, 1976