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By Earl M. Frizzell

This paper addresses considerations for the use of artificial support of pit walls in surface mines, a new project of the Bureau of Mines. Results to date indicate that a polymer-coated cable with embedded grit could provide good anchorage for stabilizing benches and highwalls, and an electronic method of recording discontinuities in the field is being reviewed and developed for application to mining. The objectives of the work in progress are to define the engineering parameters and evaluate the concepts for artificial supports in order to provide safe working environments when pit slopes are steepened to increase ore recovery and reduce overburden handling.

Jan 1, 1986

By Saul J. Escalera

Mechanisms involved in the depression of the sulfides: pyrite, chalcopyrite, galena and sphalerite with potassium permanganate have been investigated. Flotation tests were conducted using potassium amyl xanthate, Z-6, and pine oil in the absence and presence of potassium permanganate at around pH = 6. 5 naturally yielded by the sulfides in the pulp. On the basis of crystal chemistry considerations, the amount of xanthate adsorbed by the sulfides depends on the amount of sulfur and metal ions present on the surface; thus, the avidity of the sulfides for xanthate should increase in the order: sphalerite C chalcopyrite 4 galena 4 pyrite, and the ease of depression response to the permanganate action should be in the same order. Depression of the sulfides in the system occurs primarily due to the removal of the collector ions by the permanganate ions to form manganese dioxide and dixanthogen according to the reaction: 3 M(RX)2 + 2 Mn04 + 4 H20 2 ? MnO2 + 3(RX-XR) + 3 M+2 8OH where M represents the metal ion, RX the xanthate ion and (RX-XR) the dixanthogen molecule. Results seem to indicate that the permanganate ions play a triple role in the system: (1) they convert xanthate ions into dixanthogen, (2) they further oxidize the mineral surface and (3) if present in excess, they may oxidize the xanthate beyond the dixanthogen stage with the formation of CO2, H20 and SO4. All sulfides, except for chalcopyrite, showed a depression response in the order predicted regardless of the order of addition of xanthate and permanganate reagents. Chalcopyrite did not depress as easily; this behavior may be due to the avidity of the colloidal MnO2 to adsorb Cu+2 ions on its surface, this would destabilize the colloid making it coalesce with the formation of a layer of precipitated MnO2 on the surface of the mineral. The presence of this layer would prevent further action of the permanganate ions on chalcopyrite.

Jan 1, 1970

By M. Dayne Aldridge

A description is given of an experimental ventilation control system designed, built, and tested by WVU under United States Bureau of Mines sponsorship. A description is given of the control, system used and the mine-wide microcomputer-based ventilation monitoring system used with it. Test results of experiments conducted with this system at Eastern Associated Coal Corporation's Federal No. 2 underground coal mine are presented. In addition, a brief description is given of a new microprocessor based system presently being tested.

Jan 1, 1980

By Michael P. Evans

Traditionally in coal processing jigs have been used to clean the coarse coal fraction, the +3/8" or +1/4" material. Today with the advent of modern fine coal jigs in the United States, its place was moved from the coarse to the inter- mediate coal circuit, the 3/8" x 100 mesh. The most economical coarse coal circuit to build and operate is a heavy media bath circuit. The following table summarizes the cost per raw coal ton processed for a coarse coal jig circuit, and a coarse coal heavy media bath circuit. The flowsheets used to compare these two circuits are shown in Figures 1 and 2.

Jan 1, 1983

This paper presents the latest developments in the flotation model being developed collaboratively between the Julius Kruttschnitt Mineral Research Centre in Brisbane, Australia, and the Mineral Processing Research Unit of the University of Cape Town in South Africa as part of the Australian Minerals Industries Research Association (AMIRA) P9 Project. It includes: - characterisation of flotation cells using the bubble surface area flux, Sb; - relationship of Sb to the overall flotation rate constant; - determination of the froth recovery factor; - evaluation of ore floatability; - modelling of entrainment - development of the Floatability Characterisation Test Rig (FCTR); - use of the model in design and optimization of flotation plants; and - current and future work.

Jan 1, 1999

Tables

Jan 1, 1973

By G. Rinelli, Paul R. Jr. Smith

Preparation for flotation begins with dragline mining, pumping, washing, screening, and desliming. Slimes, nominally -150 mesh material, constitute large quantities of phosphate and water which are a disposal problem. Older techniques involve sizing at about 35 mesh for separate coarse and fine treatment. The plus 14 mesh fraction does not require concentration. Coarse treatment includes agglomerate spiralling, belt flotation, thickening, scrubbing with sulfuric acid, de-oiling for reagent removal, and cationic flotation of fine quartz. A recent trend is to screen at coarser than 35 mesh size and eliminate coarse particle treatment, sacrificing some grade of this product. Techniques for flotation concentration of the fine size fraction are discussed.

Jan 1, 1976

By S. D. Thompson, L. Adler

This study reviews and analyzes the empirical methods available for designing the capacities of coal mine gathering belts. The analyses lead to recommendations concerning the application and implementation of each empirical method. Operations research techniques, mainly simulation models, are also briefly mentioned, and a few recommendations are made concerning their selection and application. The objective of the study is to provide a reliable basis for the practicing engineer to properly select, apply, and implement a capacity design method.

Jan 1, 1988

By Bee R. Waples

The Alimak Raise Method, using the Alimak Climber, has proven to be a new, fast, economical method of driving raises at the Iron King Branch of Shat-tuck Denn Mining Corporation, Humboldt, Arizona. In order to fully understand the advantages of the Alimak Raise Climber, it is necessary first to describe the basic machine; second, a complete cycle of a raise round; and third, the comparative speed and economy afforded the Iron King operation by using this new method of raise driving: The raise climber consists of a drilling platform that is raised and lowered by two 6.2 HP compressed air motors that drive, through roller chains and sprockets, three worm gears connected in series. These worm gears drive pinions which grip the guide rail rack. The worm gems are fitted with spring-loaded couplings so that a small rock or grit in the rack is passed over without disturbing the mesh between the rack and the other pinions.

Jan 1, 1961

By J. Drelich

The adsorption of oleate at the surface of titanium dioxide from aqueous solutions was examined by Fourier transform infrared (FT -IR.) spectroscopy using a germanium internal reflection element coated with a thin film of TiO2. This thin film, with a thickness of 100-200 A, was deposited on the surface of a germanium single crystal by RFIDC magnetron reactive sputtering. It was found that significant adsorption of oleate from a 0.02-0.03 mM aqueous solution on the surface of TiO2 thin film occurs at neutral pH, from about pH=5.5 to pH=7.7. Adsorption of oleate at the surface of the amorphous TiO2 thin film appeared to be reversible, involving soap-acid dimers.

Jan 1, 1997

By James J. Scott

In 1910 the United States Bureau of Mines was created. It was the outgrowth of a social problem stemming from the fact that 25,000 men were killed in coal mining accidents for the period 1900-1910. Something had to be done and congress responded to the people's demands by creation of this new regulatory agency. At that time mine operators felt the new agency was too strict but nonetheless new rules were developed and enforced and results were obtained by the industry which reduced fatal accidents to less than 250 per year by 1970.*Social reaction by the general public brought about legislation which created the Federal Coal Mine Health and Safety Act of 1969 This legislation was a direct reaction to the Farmington Disaster. Operators and miners alike said "we cannot operate under this law. It is too strict, requirements are unrealistic, production will suffer, .there will not be any improvement in health and safety, etc." Consider the facts: 1. Health and safety have improved. The 1972 frequency and severity rate was the best ever for the bituminous coal mining industry, Figure 1. 2 .Production per manshift has dropped in underground coal mines. For example, in West Virginia from near 16 tons/m.s. in 1967 to nearly 11 tons/m.s. in 1971-72. However, not all of this loss can be attributable to the Act, but certainly some is. (2) The betterment of the safety of coal mining was a prime motivation behind the coal law and from that standpoint the law has been partially successful, but the loss in productivity has been a real burden to the mine operator. Everyone should recognize that the law says little in regard to production--it only relates to health and safety. Production is management's responsibility.

Jan 1, 1973

By Ehsan Nasiri, Keivan Pak Iman

Historically, boulders are a frequent source of problem in soft ground tunneling. It is important to attempt to make an assessment of the nature and quantity of the boulders, although in many cases, it will be impossible to do so with great accuracy. Boulders, can pose major problems for TBMs in terms of slowing down or halting the tunnel advance, cutter damage, and abrasive wear. Although proper selection of the TBM and the cutterhead can reduce the risks, ground uncertainties still cannot be eliminated. The paper reviews a case study of a 3480 mm diameter EPB-TBM in Toronto utilized for completion of 2.5 km tunnel in Glacial Till, crossing the CP railway, HWY 401, a creek, and a confined aquifer. Alignment consists of multiple horizontal curves including small radius curves (r=210 m) at shafts breakthrough. An unexpected boulder cluster lead the contractor to experience extreme damages to the screw conveyor, RFJ system and causing a crack in main motor plate which resulted in losing one of the six main motors. This paper reviews contractor’s solutions and includes discussion on specific claim resolution method used in this project that can be of great value in preparation of specification and GBR for similar projects.

Jun 13, 2021

By P. Somasundaran

Flotation of oxide minerals is controlled by a number of factors, such as surface potential and solubility of the mineral, concentration and type of various inorganics, properties of the collector, pH, ionic strength and temperature. The role these factors play depends on the mechanisms of adsorption of the collector inorganics or polymer additives. The major mechanisms include electrostatic interactions, chemical adsorption, chain-chain interaction between adsorbed collector species and modifications of the surface by inorganics. In real systems, flotation is, however, markedly affected by various other processes, including aging of the minerals, surface precipitation of the collector on the mineral and associative interactions between various collector species leading to highly surface active, for example, ionomolecular complexes. These effects are reviewed here with selected examples.

Jan 1, 1999

By W. H. Wilson, G. Bjarnholt, D. C. Holloway

This paper describes the results of field tests conducted on a 5x25m bench face to evaluate several new concepts for improving smooth wall blasting. These ideas involved the use of notched boreholes to direct the fractures and unconventional types and placements of explosives. The notches were made with a mechanical broaching tool, a water jet and with shaped charges. Borehole pressures were measured with an inexpensive and expendable pressure transducer developed for this program. The testing showed that at hole spacings 38% greater than normal practice, notched holes with half the normal loading density produced equivalent results.

Jan 1, 1986

By C. A. Roberts

What are the benefits and limitations of financial analysis software as a decision making tool in the mining industry? Traditionally, the assumptions and simplifications imposed by complex and uncertain information have been viewed as the main obstacle to reaching an optimum decision. Recently, however, phenomena such as corporate culture and power structure have received increasing attention as significant influences on organizational decision making processes. Studies of these phenomena have suggested an alternative way of understanding decision making processes and an alternative view of the role played by computer analysis in such processes. This paper presents these two views of decision making, and examines what each implies about the role of financial analysis software as a decision making tool in the mining industry.

Jan 1, 1992

By R. E. Hochscheid

Cyclones installed in three closed- circuit grinding systems were changed from conventional, vertical mounting to horizontal mounting with a favorable improvement in classification efficiency. In two of the installations, apex plugging problems were eliminated because horizontal mounting permit- ted the use of much larger apex orifices. Marked reduction in circulating load was accompanied by greatly reduced maintenance requirements for the cyclone and the cyclone feed pump in one of the installations.

Jan 1, 1988

By Joseph W. Mussey

Bio-epigenetic sulphur deposits occur in Pecos, Reeves and Culberson Counties of far West Texas. Sulfate reducrng bacteria, utilizing hydrocarbons as energy, transformed gypsum into replacement limestone and hydrogen sulfide. Hydrogen sulfide, retained in the porosities of the replacement limestone, was subsequently oxidized by highly oxygenated groundwaters, and native sulphur precipitated. West Texas sulphur was first recognized at surface exposures by William P. Blake, a geologist attached to the Captain Pope Military/ Scientific Expedition of 1854. Attempts were made in the early 1900's to mine these sulphur vent exposures by a retort method, but the ventures met with little success. In 1967, Duval discovered a large sulphur deposit near some of the old sulphur works in Culberson County. Duval also extended a small sulphur deposit in Pecos County. The Frasch process, developed for producing sulphur from Gulf Coast salt domes, proved successful in West Texas type sulphur deposits also. However, modifications of the process were necessary to provide economical and efficient sulphur recovery from the varied ore modes. West Texas conditions and logistics require the ultimate in productivity to be competitive in the domestic and foreign sulphur markets. Several companies, in addition to Duval, are producing or have produced sulphur in West Texas. As of the first of June 1984, a total of 29.4 million long tons of sulphur had been produced west of the Pecos -aver. Duval produced more than 88 percent of that total.

Jan 1, 1984

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 M. Scherzinger, M. Dr. Mazurkiewicz

Additional progress in comminution can be achieved if the compressive crushing principle commonly used at present is changed to one where particles are fragmented by the tensile growth of preexisting internal flaws or cracks, under internal waterjet pressure. This idea was studied in a number of tests and generated results and conclusions are the subject of this paper. It covers tests with different jets imposed on rock samples during compressive load as well as without any loading.

Jan 1, 1992

By Scott A. Crozier

Environmental regulation of the United States copper industry has evolved significantly over the past three decades and the pace of that evolution is expected to escalate dramatically during the 1990's. The paper examines, from a corporate perspective, current environmental regulation and expected trends including the development of Subtitle D regulations for mineral extraction, beneficiation and processing activities under the Resource Conservation and Recovery Act. The paper concludes by exploring existing and potential impacts on copper companies in complying with the changing environmental regulatory scheme and responsible and progressive precautionary measures companies should consider to address these issues while simultaneously addressing often competing socioeconomic demands.

Jan 1, 1992