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By Keenan. Albert M

The challenge of mining coal seams having a pitch of 30 degrees is one not frequently found in the United States, due primarily to the scarcity of such deposits. However, in the Thompson Creek District in Pitkin, Colorado, such a challenge exists to produce high quality medium volatile coking coal, and development of a longwall system is underway. The deposits under consideration are those of the Anschutz Corporation Inc. of Denver, Colorado, which are not in a virgin state. The properties were originally mined by the Colorado Fuel and Iron Corporation from 1894-1907, and by the Thompson Creek Coal and Coke Corp. from 1953-1966. Approximately five and one half million tons of coal have been mined by the above companies, attesting to its quality. The cessation of operations in both instances was occasioned by economics. Both companies employed a room and pillar system of mining, but being denied the use of high capacity mining and loading machinery because of the excessive pitch of the coal seam. This resulted in an unfavorable productivity expressed as output per man-shift, and thus the high cost of production occasioned by hand loading and semi-mechanization dictated cessation of operations. The specific location of these deposits are in Pitkin County,

Jan 1, 1971

By M. Downing

This paper gives a brief overview of impacts of coal blending on coal-fired power plants performance and discuses the preliminary results of an on-going study aimed at evaluating the effect of coal properties on the effectiveness, compatibility and thermal reactivity of coal blends. Plant survey studies reported no significant impacts on an existing plant designed for a high rank coal when switched to a blend of low-and high-rank coal. However, slight modification of some aspects (handling, fuel storage/stockpile, transportation, preparation, and general housekeeping) of plant design and operation may be necessary. The preliminary results of an on-going study at the Mineral Industry Research Laboratory shows that more compatible and better blends could be made from coals where ranks are closer than from those where ranks are far apart.

Jan 1, 1997

By Robert J. Willard

In its search for additional ways to increase understanding of rock behavior, the Twin Cities Mining Research Center has turned to the scanning electron microscope, an instrument rapidly finding application in research concerned with surfaces of materials. Since features indicative of the manner in which rocks fail may be recorded on the surfaces of fragments as disintegration proceeds, this microscope might be used as a tool for seeking and mapping these minute features. In pursuit of such features, we chose to scan a portion of the fracture surface from a quartzite disk compressively loaded to failure between two pins centered along the disk's axis. The resultant fracture appeared as a rough, diametric plane, and the fracture surface near one of the loading points was scanned with the microscope.

Jan 1, 1969

By Robert S. Foote

The U.S. Energy Research and Development Administration (ERDA) is currently conducting a national program to survey for uranium the conterminous United States and Alaska by 1980 using airborne and surface techniques. This paper discusses the techniques used and some of the results of airborne surveys conducted to date by Geodata International, Inc. Airborne gamma radiation and the earth's magnetic field data are measured to provide data leading to regions potentially more favorable for the exploration and discovery of uranium ore. High-sensitivity radiometric and magnetic field data have been gathered from an aircraft with an average surface altitude of 400 feet (Figure 1). Under most conditions, data are usable up to an aircraft surface elevation of about 1250 feet where limitations will be discussed. Results of data analysis under GJO-1632, GJ0-1644, GJO-1654 and GJO-1663 will be discussed.

Jan 1, 1976

By M. K. McCarter

In 1963, a major expansion program at Kennecott's Bingham Canyon mine converted rail operation in the upper portion of the pit to truck haulage. Since that time truck-haulage capacity has increased to about 272 000 Mg (300,000 tons) per day. The majority of this production is waste material which is deposited in monolithic dumps located on the eastern slopes of the Oquirrh Mountains. The largest of these dumps, referred to as Copper Notch and Keystone, measures approximately 1830 m (6000 ft) in length, from 180 to 300 m (600 to 1000 ft) in height, and contains some 430 Tg (470 mil lion tons) of waste. The height, structure, rapid rate of growth, and anticipated leaching suggested the possibility of dump failure. In order to evaluate this possibility, an outside consulting firm was retained in 1966 to investigate the stability of the growing dumps. Their investigation indicated that, other than superficial movement, the waste dumps would be stable under static loading, and that soil distribution was not continuous enough to sustain massive foundation failure. Since this investigation, however, several failure processes have been observed. Crest settlement occurs frequently in response to compaction and over-steepening in the upper portion of the dump surface. Over-steepening results from accumulation of fines near the crest caused by natural segregation. Normally, coarse material, near the base of the dump, exhibits an angle of repose near 0.65 rad (37"). The fine material, however, stands as steep as 0.75 rad (40"). Periodic equilibrium adjustments cause stepwise settlement (Figure 1) of the dump surface and occasional sloughing of the protective berm. Routine surface preparation by dozers and graders and frequent inspections by supervisory personnel have proven adequate in preventing problems associated with this form of crest instability.

Jan 1, 1976

By N. Arbiter

During the first four decades of flotation practice, close to 200 machine designs were patented, although only about a score were ever used commercially. By the end of that period, the rigors of use had resulted in obsolescence of most pneumatic cells, with a few mechanical cells dominating the field. After World War II, newer designs began to appear but most were modifications in varying degrees of older designs with special features added. Of the dozen or so most recent developments, almost all are pneumatic, relying on compressed air instead of impellers for motive power, although in several cases pumps supplement compressors. Table 1 lists a few of the more fully documented new cells, with their significant characteristics, along with similar characteristics of a widely used mechanical cell. New designs in general are emphasizing: bubble size control; in several cases, methods for delivering feed directly to the froth; methods for introducing and dispersing air through nozzles, eductors, packed beds, or permeable walls; and variable cell volumes, relative to capacities, ranging from very small, with less than a second of retention time, to the largest, with retention times of over 20 min. An important question is the extent to which any of the newer designs are based on locating weaknesses in current mechanical cell designs and then using these as a starting point for innovations. In the present study, the key subprocesses which must take place in a cell are outlined; mechanical cells are analyzed to establish where weaknesses may exist; and then alternative subprocesses are considered which could effect improvements. COMPONENTS FOR CELL DESIGN It is assumed that mineral surface chemistry has been modified as necessary to provide optimum potential floatability. While the cell process may affect this to a degree, cell design is primarily concerned with actualizing the existing potential floatability. The cell design problem is to provide more effectively for the following: 1) Dispersion of air to obtain an optimum bubble size distribution at an optimum ratio of air volume to feed volume. 2) A hydraulic environment which permits most effective contact of potentially floatable particles with bubbles: [Table I - Cell Comparisons* Cell Type Mechanical Column Deister Miller ASH No. of units Multiple Single Single Single Retention time min.10/20 17/27 3.8 ca. is Capacities mt/m3s 0.022/0.066 0.066/0.20 0.11 10.4 st/ft3d 1/3 0.3//0.9 m5.0 469 Air hold-up % 15/20 20 n.a. 50/80 Air escape velocity m/s 0.015/0.0200.020/0.025 n.a. n.a. ft/m 3/4 4/5 n.a. n.a. * References: Mechanical (Harris, 1976,1985), (Bassarear, 1985); Column (Travis, et al. 1987); Deister (Zipperian and Christophersen, 1985); ASH (Air-Sparged Hydrocyclone) (Miller 1989).]

Jan 1, 1989

By R. A. Metz, Willard C. Lacy

Survival of the mining industry as a viable economic entity in the United States is being seriously threatened by declining grades of ore reserves, rising operational and capital costs, and increased governmental taxes, restrictions, and subsidizing of third world competition. Discovery of major high-grade deposits is becoming increasingly unlikely. International competitiveness of the U.S. deposits will depend upon 'Yankee Ingenuity,' innovations in mining methods, metallurgical treatment, and financial arrangements, and a viable national strategy. This will require not only effective management for control of operations, but management that encourages breakthroughs in technology, financing, labor relations, and in public and governmental understanding. The mine geologist and the exploration geologist both have important roles to play in all aspects of this fight for survival of the industry.

Jan 1, 1992

By S. C. Suboleski

In a high risk venture such as mining where capital is committed and contracts are signed on the minimum of information, decisions are based primarily on production forecasts derived through consideration of such factors as management-labor relations, mining practice, variations in physical conditions and the equipment applied. Among these factors, the physical conditions offer the least opportunity for control and, due to the wide range of mining conditions that may be experienced, little effort has been made to develop objective methods for measuring their effects on mine out- put. The aim of this paper is to demonstrate a method for assessing these relationships that can be applied under a wide range of conditions both in new mines and in working sections where there is a need to determine the impact of proposed operational modifications. psing empirical data from active underground mines, a mathematical model was developed to derive a set of regression equations for predicting production as a function of mining conditions

Jan 1, 1980

By M. Soya, M. Imazu, Ö. Aydan

"SUMMARY Taru-Toge tunnel is being constructed using drilling-blasting technique as a part of expressway project connecting Shin-Tomei Expressway and Chuo Expressway at the boundary of Shizuoka and Yamanashi Prefectures in the Central Japan. The maximum overburden is about 400 m. The authors have been carrying out a monitoring program to measure dynamic and multi-parameter responses of tunnel during and soon after the blasting operations using a multi-parameter monitoring system (Acoustic Emissions (AE), Electric Potential (EP), Temperature (T), Humidity (H) and Air Pressure (P)) and stand-alone type compact accelerometers developed by the first author. The measured response involves dynamic vibrations and other measurable parameters caused by blasting as well as by stress-redistribution around the tunnel face. This is one of the first attempts in the world to measure the response of rock mass caused by blasting at a very close vicinity of the tunnel face. In this paper, the authors present the outcomes of this unique monitoring study on the dynamic responses of the Taru-Toge tunnel during excavation and discuss their implications in actual applications. INTRODUCTION The real time monitoring of the stability of tunnels are of great importance when tunnels are prone to failure during excavation such as rockbursting or squeezing (i.e. Aydan et al. 1993, 2001). Experimental studies by the authors showed that rock indicates distinct variations of multi-parameters during deformation and fracturing processes (i.e. Mizutani et al. 1976; Aydan and Daido 2002; Aydan et al. 2003, 2011). These may be used for the real-time assessment of the stability of rock structures. An application of this approach was done to the Taru-toge tunnel a part of expressway project connecting Shin-Tomei Expressway and Chuo Expressway at the boundary of Shizuoka and Yamanashi Prefectures in the Central Japan (Imazu et al. 2015). The parameters measured involve electric potential variations, acoustic emissions, rock temperature, temperature and humidity of the tunnel in addition to the measurements of convergence and loads on support members during the face advance."

Jan 1, 2016

By Wendell E. Bearce

At the, Crescent Valley Mine of the Hanna Coal Company, several 10,000 ton unit trains of 41" x 0 strip coal are loaded per week during the lake season. This is accomplished without the use of any accumulation of prepared coal. A large raw coal pile is built up during the winter months adjacent to two truck dump bins. This is added to whenever trucks are coming in from the pits and trains are not being loaded. During the loading of trains, trucks from several pits dump into the truck hoppers and coal is also dozed in from the pile. At a rate up to 3200 tons per hour this coal is screened, the plus 6" hand picked, the plus 4" crushed, and' all weighed and sampled as it goes directly to railroad cars being handled on two tracks by car retarders. With such an arrangement it is possible to exercise some control over coal quality, if it can be assessed rapidly. For instance, if the moisture rises to a level where it seems probable the BTU per pound will be reduced to the point where the contract calls for penalties, the trucks from, the wettest pit may be stopped, more or less coal may be moved in from the stockpile, or other measures taken to assure that the average BTU of the trainload will be satisfactory.

Jan 1, 1967

By R. L. Pearson

The 1987-88 Denver Brown Cloud Study was performed to determine the sources of the particle cloud which forms over Denver each winter. The study was organized under the leadership of Colorado Governor Roy Romer , EPA Region VIII and the Greater Denver Chamber of Commerce. The study was sponsored by over 40 organizations representing governmental agencies, the natural gas industry, the coal industry, utilities, oil companies, railroads, the motor vehicle industry, and other Denver area companies and organizations. The cost of the study was $1.5 million which was raised almost entirely from private sources. The study team was headed by Dr. John Watson of the Desert Research Institute of the University of Nevada. Dr. Watson is a recognized expert in conducting studies of this type.

Jan 1, 1990

By C. Hansen, J. Killey

This paper discusses the replacement of AEROFLOAT ® 1 25 promoter by AERO ® 5688 promoter at Sonora Mining Corp.'s California Mother Lode concentrator. Flotation concentrate is trucked 120 miles to a leach plant in Nevada, so the reduced mass resulting from higher gold grades and reduced talceous gangue and barren pyrite resulting from this change in promoters has brought about a major decrease in shipping costs. Preliminary laboratory testing indicated that free milling gold and controlled amounts of pyrite could be floated using Aero 5688 promoter with reduced dosages of Aero 350 xanthate.2 Extensive plant trials confirmed that the new reagent suite could indeed maintain gold recoveries while reducing total mass. Improved froth characteristics also improved operating flexibility in treating various ore types, and overall reagent costs have been reduced.

Jan 1, 1991

By Frank C. Appleyard

As the environmental movement gained force during the past few years, it was inevitable that attention would be focused on surface mining, and we have seen this method of extracting minerals from the ground come under heavy attack by conservation groups, the press and television, legislators at all levels of government,, and the public at large. It is difficult, and in some situations, perhaps impossible, to measure either the need for, or the results of, land reclamation in absolute terms. Therefore, much of the criticism of surface mining has been based upon subjective analysis rather than hard data, with the result that discussion of the subject often includes a fair amount of emotional response. To be fair, this reaction is not limited to just our critics; even we hard headed engineers sometimes respond in the same way, an observation with which you may agree when I finish this talk. This leads to the thought that whether you are for it, or against it, land reclamation in many respects is a state of mind. That is, our reaction to it can vary considerably, depending on how far we have thought it through. And think it through we must, because the pressures being brought to bear need to be met with positive actions if the problem is to be brought under control, and in the next few minutes I would like to discuss from a management point of view some ideas which might aid in this thinking process. It would be a mistake, I believe, to think that the current energy crisis will suddenly bring the environmental movement to a stop, and therefore, we can relax and go back to running our busi¬ness the way we used to. This is not realistic; on the contrary the energy crisis is focusing attention on the limitations of our natural resources as nothing else could, and with respect to land

Jan 1, 1974

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

"Mine Safety and Health Administration (MSHA) regulations require underground coal mines to use refuge alternatives (RAs) to provide a breathable air environment for 96 hrs. One of the main concerns with the use of mobile RAs is the heat and humidity buildup inside an RA. The accumulation of heat and humidity can result in miners suffering heat stress or even death. MSHA regulations require that the apparent temperature in a fully occupied RA must not exceed 95°F. To investigate this issue, the National Institute for Occupational Safety and Health (NIOSH) conducted testing on a 23-person tent-type RA in its Experimental Mine (EM) in a test area that was isolated from the mine ventilation system. The test results showed that the average measured air temperature within the RA increased by 9.4°C (17°F) and the relative humidity (RH) approached 94 %RH. The test results were used to benchmark a thermal simulation model of the tested RA. The validated thermal simulation model predicted the average air temperature inside the RA at the end of 96 hours to within 0.6°C (1.0°F) of the average measured air temperature. INTRODUCTION If an accident occurs in an underground coal mine, miners who fail to escape from the mine can enter an RA for protection from adverse conditions, such as high carbon monoxide levels. One of the main concerns with the use of mobile RAs is the potentially adverse thermal environment inside an RA from the metabolic heat of the occupants and the heat released by the carbon dioxide (CO2) scrubbing system. Moreover, the humidity within the RA will increase through occupants’ respiration and perspiration and from the chemical reaction within the CO2 scrubbing system. The accumulation of heat and humidity can result in miners suffering heat stress, heat stroke, or even death. In its 2007 report to Congress, the National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) recommended that RAs should be designed to ensure that the internal apparent temperature (a temperature-humidity metric) in an occupied RA does not exceed 35°C (95°F). However, a standard method to determine compliance with this metric does not exist. The heat transfer process within and surrounding an RA is very complex, and is not easily defined analytically or experimentally. To investigate the related issues, OMSHR conducted heat and humidity testing on a 23-person tent-type RA in its Experimental Mine (EM) in a test area that was isolated from the mine ventilation system. During the testing, numerous parameters were measured: heat input to the chamber, the air temperature and relative humidity inside the RA, the air temperature in the mine, the mine strata temperatures versus depth, and the airflow inside and outside the chamber. The focus of this paper is on the temperature rise within an RA. TAITherm heat transfer analysis software was used to develop a thermal simulation model of the RA as it was tested in the mine, using the test results as the benchmark. Both sensible and latent heat were used in the test and the model."

Jan 1, 2016

By Carrie Smith

Along Michigan’s Upper Peninsula lies the Marquette Iron Range, home to iron mines. Just southeast of the region is the small town of Iron River, where Mary Korpi spent most of her chidhood and early adulthood. Though living in the heart of mining country, the industry did not pique her interest while growing up. As the daughter of two educators, she envisioned a different future for herself. Now, decades after working for one of the largest gold companies, she is gearing up for her term as the Society for Mining, Metallurgy & Exploration’s 2026 President.

Mar 1, 2026

By N. W. Johnson

Two analysis tools which have been applied to problems in industrial Flotation processses are the application of kinetics and detailed mineralogical or liberation data, both on a size-by-size basis. The paper describes practical examples of the application of kinetics to examination of the entrainment recovery mechanism, the retardation of valuable minerals at the commencement of flotation sections and the resolution of problems related to valuable species with reduced rate constants at the end of sections. Examples of the usefulness of size-by-size liberation data for monthly composite samples of products from a concentrator are also described.

Jan 1, 1985

By Pafos Busch, Martin Fischer, Johannes Jaeger

The Spitzenberg Tunnel is a 600 m (1,970 ft) long twin tube motorway tunnel on Germany’s Autobahn A44 between Kassel and Eisenach. Since flexibility was considered to be very important in the continuously changing geological conditions, NATM was chosen as the construction method. When passing an old quarry with only 1,80 m (6 ft) of overburden, the excavation works became extraordinarily challenging. This paper not only describes the special methods, like double sidewall drifts and pipe umbrellas applied in this zone but also highlights the cooperation between the parties involved, which in combination made the project a joint success.

Jun 13, 2021

By C. I. Basilio

Pearson's hard and soft acid and base (HSAB) principle may be applied to flotation systems. The HSAB principle states that hard acids prefer to bond with hard bases and soft acids prefer to bond with soft bases. By determining the Drago E and C parameters for the different components of a flotation system, the HSAB principle could be used to explain the selectivity of some collectors such as thionocarbamates against some minerals. Determination of these parameters is done by utilizing Drago's theory and flow micro-calorimetry.

Jan 1, 1991

By Dennis C. Parker

The Porters Creek clay is mined for its absorbent properties. The formation is part of the Upper Mississippi embayment and is recognized in Alabama, Mississippi, Tennessee, Kentucky, Illinois, and southeast Missouri. Major minerals in order of abundance are Montmorillonite, Quartz, Illite, Kaolinite, and Chlorite. Mining consists of open pit operation utilizing track loaders or scraper. The clay is dried or hardened in rotary kilns and crushed to size by roll crushers. The clay granules are sized and air classified prior to storage for shipment or packaging. Granules are sold for pet absorbents, oil absorbents, anti-skid material, fertilizer, and pesticide carriers.

Jan 1, 1979

By M. F. Martin

Dewatering aids are chemicals which enhance the efficiency of mechanical dewatering equipment such as vacuum disc filters and centrifugal dryers. A new dewatering aid has been developed which significantly lowers the moisture content of the mineral concentrate and causes none of the undesirable side effects normally associated with dewatering aids. Highlights of product development from laboratory screening through field testing will be discussed.

Jan 1, 1985