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Sheaves are a critical safety component in a winding system and are expected to survive such extreme loading events as rope break. Sheave designs have often been developed and evolved empirically, consequently many existing sheaves are not necessarily subjected to the detailed analyses that are possible using todayÆs design tools. The design philosophy for sheaves is that the rope should be the weakest link in the system so that associated equipment can function safely for any load up to rope break. A number of failure mechanisms must be considered, but buckling is often prominent. During the course of investigating the feasibility of upgrading the hoisting capacity of a winding system, the capacity of all critical components was reviewed. The sheaves in the system were found to have insufficient spoke buckling capacity for the specified rope. A proposal to increase the spoke buckling capacity by connecting spokes together using a simple tie arrangement was evaluated and found ineffective. An alternative tie arrangement concept was developed and evaluated and shown to be adequate. This paper describes the finite element model, analysis approach and results for the original sheave and the two modifications. The contribution of the sheave rim to the total buckling capacity is evaluated. Some practical issues for spoke tie modifications are discussed.

Jan 1, 2005

By R. W. Bartlett

DISILICIDE coatings, MeSi2, on refractory metals are usually grown by a solid-state diffusion reaction similar to the parabolic oxidation of metals. Two or more silicide compounds occur in each of the binary silicon-refractory metal systems. When an adequate source of silicon is available during the coating process, the lower silicide compounds are usually not formed.1 However, during service application of the coated refractory metal, continued heating causes further diffusion and growth of the lower silicides. A study of the growth kinetics of the lower silicides in the molybdenum and tungsten binary systems with silicon was previously reported.2 The present study is concerned with the growth kinetics of Ta5Si3 and Cb5Si3, formed as conjugate layers between TaSi2/Ta and CbSi2/Cb diffusion couples, respectively. Diffusion couples consisting of disilicide-coated tantalum and columbium sheet coupons were subjected to diffusion heat treatments, cross-sectioned, and scanned by an electron-microprobe analyzer to determine the relative X-ray intensity profiles. These profiles correspond closely to concentration profiles for the constituents, and were used to identify phases and locate phase boundaries. The analysis of a single specimen after a diffusion-anneal provides only one value for the Me5Si3 phase thickness, corresponding to the time and temperature of the diffusion treatment. Consequently, each isothermal curve showing the rate of accumulation or depletion of silicide phases required several samples with identical diffusion temperatures but different diffusion times. The disilicide coatings were prepared by pyrolizing commercially pure silane in a hydrogen carrier gas. The hydrogen was purified by passage through a palladium membrane. Commercially pure tantalum and columbium sheet metal coupons, 0.005 by $ by 2 in., were used. All of the coated specimens for each system were prepared together in a single group in order to minimize coating variations among individual specimens. During pyrolysis, the brightness temperature was maintained at 1200°C. With suitable flow rates at this temperature, only the disilicides of tantalum and columbium were formed in detectable amounts. Coated specimens were subjected to diffusion an-neals in a tube furnace with automatic proportional control within ±10°C. A H2-Ar mixture, deoxidized and dried over anhydrous magnesium perchlorate, was used to prevent oxidation during the diffusion anneal. Diffusion couples were cross-sectioned, polished and examined with an A.R.L. electron-microprobe X-ray analyzer. Both metal constituents in each specimen were simultaneously scanned using a 1-p beam spot size and either 1- or 2-µ steps. Analyses were performed using the Ka radiation of columbium and silicon, and the La, radiation of tantalum. For all specimens, an acceleration voltage of 30 kv was used, and integration was made against the specimen current. LiF and A DP monochrometers were used to isolate characteristic radiations. Three or more traverses were made on each specimen. The intensity scales were adjusted using the constituent metals and standard samples of the silicide compounds which had been verified by X-ray diffraction. The relative intensity profiles were used directly, in conjunction with the standard samples, to identify compounds and phase boundaries. The stoichiometries differ considerably between the silicide compounds in both systems, and the homogeneity range for these silicide compounds is narrow. These characteristics result in marked differences in relative intensities of the fluorescing elements—differences which permit ready identification of phases and phase boundaries. Projections of both electron back-scattered images and characteristic

Jan 1, 1967

By S J. Hawke, L A. Dominguez

In non-ferrous metal mining operations, it is generally necessary to crush and grind the ore to a very fine particle size to effectively liberate the contained mineral from the host rock. Fragmentation by blasting is the first stage of this comminution process.Numerous studies and independent modelling of the Mine to Mill process have demonstrated the potential for significant downstream productivity improvements from improved blast fragmentation. However, safety and environmental constraints associated with the blasting process usually limit the extent to which blast energy or powder factor can be increased.An effective blasting solution has been identified that enables the safe utilisation of powder factors several times higher than those used conventionally to provide significant improvements in fragmentation. The solution uses a static ‘blanket’ of broken rock overlying the blast to contain this increased blast energy and control rock movement. To produce this broken layer of rock, the subdrill in each blast is significantly increased to preblast (or precondition) the entire stemming region of subsequent blasts on the next mining bench.The solution has been evaluated at a large open cut poly-metallic mine in Mexico. Results from the application of this technique have shown significant improvement in run-of-mine fragmentation, with subsequent downstream productivity improvement indicated.CITATION:Hawke, S J and Dominguez, L A, 2015. A simple technique for using high energy in blasting, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 321–326 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By D. D. Walker

Scheelite, the most abundant tungsten mineral in the Philipsburg region of Montana, is found in replacement deposits and along fissures and cracks in limestone at various distances from contacts with acidic igneous rocks. It also occurs at the limestone-igneous contacts, but typical garnet tactites are developed in only a few places in the region. The most favorable host rocks for scheelite mineralization are the Jefferson, Hasmark, and Madison limestones. Scheelite is exposed in float, outcrops, and surface and mine workings along a 2-mile-wide belt extending southwest from Lost Creek beyond Silver Lake, a distance of 15 miles or more. (See fig. 1.) Some scheelite is found in veins formerly mined for silver. Powellite and molybdenite occasionally are present with the scheelite. Hubnerite occurs in quartz veins in the Black Pine area 10 miles northwest of Philipsburg. These quartz veins occur in the quartzites of the Precambrian Spokane formation. Tungsten production in the region has come almost exclusively from scheelite deposits, both lode and placer. During a 6-year period beginning in 1943 a total of 142.0 tons of 63-percent W03 concentrate was produced by H & H Mines Co. In the early 1950's, the Trigger mine produced 4,000 tons of 1-percent W03 ore and the Tip Top 650 tons of 2.0-percent W03 ore and 2,906 tons of 2.2-percent ore. There has been sporadic production from some of the smaller properties in the area.

Jan 1, 1960

By H. A. Stoess

The Minerals Industry makes heavy demands for and on its Material Handling equipment. It also gives progressive management the opportunity for considerable savings, ad consequently increased profits. In some cases, cost of Materials Handling amounts to 40°/o of the total cost of the ultimate product. Handling costs are hidden in overhead, indirect labor, excessive maintenance, productive workers performing handling tasks, and, a great many more. Even though Materials Handling is the oldest occupation of mankind, it is only within the past twenty years that it has emerged as a specialized field. While this industry has made full use of all types of mechanical and vibratory conveyors, pneumatic conveyors in their proper application can be a distinct asset. me use of pneumatic conveyors by this industry however is limited- to a certain extent by the particle size of your products through the various phases of manufacture, as well as their bulk density. However, with increasing knowledge of the fluidization of dry materials, their use is becoming more wide spread.

Jan 1, 1962

By Arne Landsberg

The Bureau of Mines has undertaken research to elucidate the chemistry involved in the efficient recovery and control of minor elements in base metal smelting operations. These elements should be effectively recovered not only because they have commercial value, but also because of their potential hazard to workers' health and the environment, if they are not controlled during processing. Cadmium, a minor metal in zinc ores, is the subject of this report. The roasting step of the complex zinc-smelting process was chosen for investigation because of the high potential for removing cadmium by volatilization during this primary stage. Commercial roaster feed materials were used to determine the sequence of reactions and the effect of these reactions on the volatilization of cadmium. Electron microprobe examination of both the commercial roaster product and oxidized sulfide solid solutions prepared in the laboratory showed that oxidized iron was of prime importance in preventing cadmium volatilization. The mechanism by which iron prevents cadmium volatilization is proposed, and a preheating technique is recommended for more effectively recovering cadmium prior to roasting.

Jan 1, 1981

By Steven E. Mischler, Jay F. Colinet

The study analyzes the impact of the Continuous Personal Dust Monitor (CPDM) on reducing overexposures to coal mine dust. It compares compliance sampling data before and after the implementation of the CPDM and the 2014 MSHA dust rule. The results indicate a significant reduction in the percentage of samples exceeding the dust standard for various mining occupations, highlighting the effectiveness of the CPDM in improving miners’ health and safety.

Feb 22, 2022

The copper-clay deposits consist largely of goethite and clayey mudstones carrying native copper, cuprite, and chalcocite. The mudstones are of Ordovician age, are interbedded with Fe-Mn carbonates, and probably contained syngenetic iron and copper sulphides. The secondary copper minerals have been derived from post-Devonian weathering in situ and also by deposition from surfaee and underground waters draining the adjacent mineralized volcanic rocks.

Jan 1, 1969

By P J. Fairfield

This paper reflects on the author’s experience working in site-based technical and management roles over a 29 year period, and the past 12 years in internal and external consulting roles. It discusses the author’s experiences and observations of operations management, and the significant value of the technical specialist’s role in providing management with information on what to base tactical decisions, which may or may not be part of a defined strategy.The landscape of mine management changes with the cyclical nature of commodity prices driving operating and capital prudence, as operations change their focus from expansion and growth to staying in the game. The role of the mine manager and management team in navigating through these changing times, attitudes and stages of the project life can influence the success or otherwise of many projects.Technical knowledge is one of the key drivers in realising or destroying the value of a project or operation. As managers focus on people management, management systems and processes, recognising and understanding value in underlying technical knowledge, and getting back to the fundamentals/basics, can be overlooked. In reaction to the fluctuating commodity cycle, managers implement changes through optimisation, fast tracking or parallel streaming, expansion projects and changes in the application of technology. These responses occur against the background of changes in the appetite for risk, acceptance of project uncertainty and changes in personnel which result in a loss of knowledge and experience – often at critical times.This paper shares the author’s experiences and lessons learnt in dealing with and observing these issues. The author questions whether we really understand our projects and are valuing the most important asset, our people and, in particular, the technical specialist and their experience and knowledge.CITATION:Fairfield, P J, 2016. Staying in the game – the importance of engineering-based decisions, in Proceedings International Mine Management Conference, pp 67-74 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By W. A. Lang

Introduction In this review, which is the fifth of the series on the Progress in Coal Technology, an attempt has been made to outline some of the more important developments that have taken place in coal carbonization during the last decade. Research into both high-and low-temperature carbonization has been active for three principal reasons: (1) the growing shortages in most countries of high-quality coking coals; (2) the demand for smokeless fuels for domestic purposes; (3) the need for metallurgical coke for the increased output of steel in the post-war years. The growing importance of coal tars as a source of chemicals for the preparation of synthetic products and of coal gases for the recovery of sulphur is evident. Many of the researches initiated because of wartime necessity have been continued .and even expanded in the post-war years. High-temperature carbonization with a suitable coal yields a strong coke which is used primarily for metallurgical purposes, a tar with good marketable value, and a large yield of gas of medium calorific value. Low-temperature carbonization gives a more free-burning solid product suitable for a domestic fuel, a high yield of a tar which is generally regarded as superior to high-temperature tar for chemical purposes, and a smaller yield of a higher-heat-value gas.

Jan 1, 1951

By D. J. Bowen

"Abstract -The Great Dyke extends for 540 km along strike, to unknown depth, and varies in width from 3 km to 11 km. Rb/Sr age determinations gives values of approximately 2470 Ma.The Dyke consists of a variety of mafic and ultramafic rocks, many altered to serpentinites. These include, from top to bottom, successions of gabbro/norites, pyroxenites, peridotites/harzburgites, and dunites/picrites.The layers dip in from either margin, steepest at the edges (20°) and flattening toward the central sections. Four separate complexes are present. From north to south these are termed the Musengezi, Hartley, Selukwe and Wedza Complexes, and are described as 'boat-shaped' or 'pig-troughed'. All are similar in petrological sequences. Physiographically, the Dyke is spectacular in the north, where as a mountain range it meets the Zambezi Escarpment. Elsewhere in the central parts there is little surface expression and wide open treeless vleis. Dyke rocks cut through granite and schist belt terrain and are termed 'The Magnesia Belt'.Vast mineral resources exist. These include chrome, asbestos, platinoids, nickel, copper and gold. Up to eleven chrome seams numbered from top to bottom occur in the lower ultramafic sequences. Seams are narrow at 10 cm to 30 cm but of high grade. The platinum occurs 10 m to 40 m below the norite/pyroxenite contact.A 60 m wide zone of Light Sulfide Mineralization (LSM) of Jess than 1% sulfides extends from the lower gabbronorites into the upper pyroxenites. In this LSM, four enriched zones carry up to 5% sulfides. The most widespread is termed the Main Sulfide Zone (MSZ), below which is No. 2, No. 3 and No. 4 Sulfide Zones. The MSZ carrying pyrite, pyrrhotite and chalcopyrite is a multi­ element ore with components of PGE (Pt-Pd-Rh), nickel, copper and cobalt, and gold and silver.Extensive exploration programs have been carried out and the intention is to begin large-scale mining. However, with Russia supplying metals to the western markets, South Africa's cutback on production, and an end to the Cold War, delays have arisen."

Jan 1, 1994

By Marco Olper

The Italian company Engitec Impianti has developed a new electrochemical technology for the treatment of Electric Arc Furnace (EAF) flue dust generated in steel mini-mills. This process is based on a new and completely different concept from the Waeltz technology applied at present and allows, due to its modular nature, for an erection on the steel producer's site. Engitec Impianti spent US $700.000 constructing a 500 t/y throughput pilot plant at Pittini Group's Ferriere Nord mini-mill in Osoppo, Italy in order to demonstrate the process capabilities and obtain the data for a commercial plant design. The paper describes the pilot plant performances and the engineering criteria for a commercial unit of 10.000 t/y throughput. The feasibility study demonstrates a pay-back period of 3 - 4 years for the commercial plant.

Jan 1, 1995

By H. Kenworthy

Small batches of fluorspar flotation concentrates were made into nodules and pellets on a laboratory scale. Several of these were rated acceptable by laboratory evaluation methods. The most satisfactory pellets were produced by mixing fluorspar with about 12.5 percent of water, by weight, and 4 percent of organic binders. These binders) for the most part) originated from petroleum and wood-pulp industries. They were generally difficult to handle and were not easily incorporated with the fluorspars tested. Most of them seemed to have an aversion for damp fluorspar and had to be forcibly mixed with the fluorspar; which was then formed into pellets by pressure. Substitution of fuel oil in varying amounts in the binders enhanced the mixing and penetrating qualities of these binders but at the same tire tended to make the pellets more porous. Tall oils performed the same function to a lesser degree and usually decreased the water absorbency of the finished pellets. Heat-treating temperatures to set up these binders were moderate -about 5000 F. for 30 to 50 minutes was usually enough for both drying and heat treating. Nodules made with 1-1/2 to 2 percent of bentonite as a binder were easily mixed and formed. They required a high degree of heat (about 1,500° F.) to develop their strength and were quite water-absorbent when finished. Two fluorspars were examined for weight and fluorite loss after heat treatment at similar temperatures. Both showed a definite wej.ght and analytical loss of fluorite. Bentonite was used also as a binder to successfully nodulize finely ground oxides of iron, manganese, and nickel.

Jan 1, 1951

By Mark J. Zdunczyk

"Frac sand is industrial silica sand much like glass, foundry, filtration and blast sand. The sand must meet certain specifications set forth by the industry that consumes the product. The production and consumption of frac sand has experienced record growth in the last 10 years because of new oil and gas drilling, new horizontal well drilling, multi-stage fracturing and the stimulation of older wells that have little or no production. Frac sand is needed to “prop open” the fractures in the rock reservoirs to allow oil and gas to flow out more freely.According to the U.S. Geological Survey (USGS), the estimated production of frac sand in 2015 was 71 percent of the total production of industrial silica sand or 67.4 Mt (74.3 million st). This is a decrease of about 12 percent from 2014. However, the silica sand industry and other industry sources estimate only 50 Mt (55 million st) of frac sand were produced in 2015. In recent years both the USGS and industry studies have been very close in estimating the production of frac sand but with the recent downturn in frac sand production, perhaps, reporting to the USGS was not as accurate. These discrepancies may be that the USGS statistics are based on voluntary reporting by the industry and some companies report their approximate production, others may not. It is always difficult to obtain accurate production figures of any industrial mineral or construction aggregate operation as most companies tend to keep those figures somewhat confidential. It is certainly accurate to report that the production of frac sand had decreased since the last quarter of 2014 and through 2015. The oversupply of oil and natural gas has led to this decline in frac sand usage. Oversupply has idled drilling rigs and well completion activities. World Oil Magazine reports that 2015 was the worst year for rigs in a quarter century. The only wells being completed are those that have contract agreements to do so, others have been capped. Very few new wells are being drilled. Since about 98 percent of well completion is sand and water, the sand supply has caught up with the demand. There are some bright spots in the “oil patch” as the Permian Basin in Texas and the Woodford Shale in Oklahoma have kept pace somewhat with drilling and completion. It has been reported that the frac sand producers in the Brady-Voca, TX area are producing to nearly capacity. The northern frac sand producers like those in Wisconsin, Illinois and Minnesota are feeling the downturn because of the cost of shipping sand to these moderately active basins and plays. The “rule of thumb” is that freight is 2/3 and sand is 1/3 the cost."

Jul 1, 2016

By D. Bessinger, J. M. A. Geldenhuis

High titania slag is produced from the smelting of ilmenite. These slags contain approximately 85 per cent TiO2 and consist mainly of a M3O5 solid-solution phase. During cooling the slag can decrepitate to a fine particulate material, which decreases the value of the product. Based on X-ray diffraction analyses of the decrepitated slag after cooling, it was found that the M3O5 phase had almost disappeared. The disappearance of the M3O5 phase was linked to oxidation of the slag. A M6O11 phase formed in the decrepitated slag. It is postulated that decrepitation of high titania slag is caused by volume changes due to the oxidation of the M3O5 phase in the slag.

Jan 1, 2005

By D. A. Keefe, O&apos

The electrowinning of beryllium from beryllium oxide (BeO) using a molten-salt electrolyte composed of 56 LiF-37 BeF2-7 BeO (mole-percent) was investigated. Anodes made of porous carbon were found to be superior in current-carrying capacity and gave a lower cell voltage than other types of anode material tested. When porous carbon anodes were used) the resultant increase in anode area prevented anode passivation. The cell voltage was 3.3 volts) and electrode current efficiencies of 50 to 70 percent were obtained. The electrodeposited beryllium was recovered as beryllium powder or was coalesced to metal beads by heating to 1,300° C.

Jan 1, 1970

By K. Tarr

Acid-producing mine tailings are present at many active and inactive mine sites and pose an environmental liability due to the potential for acid rock drainage. Acid rock drainage originating from a tailings pile, a waste rock pile, or exposed sulfide-rich rock, can cause discoloration and turbidity in receiving waters, and the loading of ions mobilized by the acid can cause a decrease in aquatic flora and fauna, and reduction in the quality of groundwater. The primary cause of acid generation is the oxidation of sulfide minerals, predominantly pyrite and pyrrhotite. Considerable mine tailings are being stored on surface in vast tailings impoundment areas across Canada. In the tailings within this study, from the Sudbury, Ontario area, the sulfide mineral of primary concern with respect to acid generation is pyrrhotite. Different tailings types show varying and progressive degrees of oxidation correlating to their specific sulfur contents. The degree of oxidation is determined by the relative extent to which the sulfides have reacted as well as the depth of oxidation within the tailings. Natural Resources Canada, CanmetMINING is dedicated to research supporting the Green Mining Initiative, a program reducing business risks by demonstrating practices that reduce environmental impacts. In cooperation with the Canada Mining Innovation Council (CMIC), applied research aims to reduce land disturbance, waste volumes, and releases to the environment. By reutilizing tailings from vast impoundment areas as a component in backfill, the potential environmental impact would be lessened considerably, due to the reduced tonnage stored on surface long-term. From an operating perspective, there is a need for supplemental feed for backfill from time to time. The reclamation of old tailings for use in backfill is also driven by the fact that old tailings ponds may not be structurally stable, and it may be more cost effective to remove the tailings than to upgrade the impoundment structure. However it is imperative that these old tailings be fully characterized to determine their suitability for use underground, in order to ensure the long-term integrity of the resulting backfill matrix. A study was conducted to investigate the feasibility of tailings reclamation from old impoundment areas as a significant component in backfill. The materials were first physically and chemically characterized, followed by preparation of samples to determine optimal mix proportions for strength development for both paste and hydraulic fill compliance. It was found that the amount of oxidized tailings included in the backfill material had a profound effect on both the segregation and settling properties of the backfill matrix, as well as the mechanical properties of the samples. The strategies for decision-making, based on the criteria for material characterization, mining plan, and cost effectiveness are discussed.

Aug 1, 2013

By C. Swart

Automation technologies are increasingly adopted in different mines world-wide. This paper presents the technical aspects of vehicle automation applications at two Noranda operating mines. Teleoperation of 5 LHDs at Noranda?s Bell Allard mine is used in order to meet aggressive mining requirements under difficult conditions. The equipment is performing under high demand for reliability and performance. In order to further increase performance, automated loading has been commissioned on one of the LHDs and is being tested. Results to date indicate improved performance with respect to an operator through better filling of the bucket, fewer passes at the muck pile and shorter cycles. Noranda?s Brunswick mine is currently commissioning an automated haulage zone where two optically guided trucks transport ore from a remotely operated chute to two ore passes. Expected operational advantages include increased system capacity and enhanced safety and comfort for the operator. Monitoring to date indicates that the trucks can operate reliably under the conditions imposed by mine production.

Jan 1, 2002

By M. G. Lipsett

One challenge in applying information technologies in Mining is building a business case. In Mine Maintenance, there is a complex flow of information that contributes to making informed business decisions. By understanding those information relationships and the cost of wrong decisions, analysts can estimate the value of information flow. Developers can then ensure that systems deliver key information in an accurate and timely way. In this paper, general maintenance decision-making is discussed, with examples of how model-based analysis can improve the information delivered to decision makers.

May 1, 2001

By A. B. Cecala

The Bureau of Mines performed a study to determine optimal locations for longwall face methane monitoring equipment. Longwall face ignitions continue to be a concern to the U.S. coal mining industry. Gains in ignition control technology have been somewhat negated by advances in longwall productivity. More reliable, heavy-duty longwall face systems generate higher production rates and increase methane liberation rates. These rates will likely continue to rise in the future as further coal production increases occur. Efforts will continue in the areas of methane drainage, methane containment, and methane dilution. In addition, more effective face methane monitoring is needed. As technology continues toward automated longwall panels, the importance of monitoring for methane at the shearer becomes even more significant. Since the primary face ignition source is the shearer mining machine, the Bureau ran tests to determine the best location to take methane readings on the shearer. This information, in conjunction with data obtained from field studies, provides a knowledge base for selecting optimum face methane monitoring locations.

Jan 1, 1993