Search Documents

By C. I. Walker

Field tests at a number of large mineral processing operations have been undertaken to better understand the wear life impact of different aspects of pump design, materials of construction and maintenance procedures. Data are presented for wear rates, and typical result variability is explored. To improve the availability of pumping equipment in a milling circuit it is not only important to improve the wear life, but also reduce the variability in the wear life of components so that the incidence of premature failure is lessened. Localised gouging wear due to flow separation and turbulent eddy formation is often the point at which part-holing occurs. A number of improvements to the design of pump impeller and throatbush (suction side liners) to reduce the localised gouging wear are outlined. Also, results are presented on the use of composite materials (mix of metal, rubber and ceramic) for throatbush materials to protect specific areas against wear.

Jan 1, 2012

By Harry E. Tufft

Data were obtained by the writer from a number of the large coul-mine operators in Illinois, on the consumption and cost of timber used in their mines and the quality of the timber now being used as compared with former years. This information supplemented by comparative date for previous years published in bulletins of the filinois Coal Mining Investigation series, and other sources, is presented below. This survey is part of a cooperative study with the . S. Forest Service, of the mine timber situation, with particular regard to the economies to be derived by better selection, preparation, and storage of timber, and especially treatment with preservatives to prolong the life. Geo. S. Rice, chief mining engineer of the J. S. Bureau of Mines, under whose general direction the work was done, gave valuable advice and criticism. R. B. Miller, State Forester, contributed helpful data which he had recent- ly obtained in an independent study of the mine-timber situation in Illinois.

Apr 1, 1923

By P. C. Thakur

The productivity in coal mines, measured in terns of the output per manshift depends largely on the efficiency and speed of men and materials transport between working faces and the surface. The mechanization of coal winning and material handling processes has led to a great rise in the mine productivity (1). Early applications of power in U. S. coal mines were mainly electrical. The excellent traction available with the DC motor and the ease of the distribution of the DC power have made trolley wire installations for haulage very popular. In shallow mines with very limited emissions of methane it did not constitute a major hazard but as mine depths increased and corresponding emissions of methane also increased fire and methane ignition hazards have become very serious. Conveyors have proved economic where intense mechanization of coal faces generates a large output of coal from a single face, but the fire and respirable dust hazard associated with them are no less serious. Recognizing these shortcomings, the Federal Coal Mine Health and Safety Act of 1969 laid down numerous provisions for the safe use of trolley-wire haulage and conveyors (2) which generally improve safety but in some cases complicate mining operations and have decreased productivity significantly since 1969. In course of time as coal mines become deeper and hence gassier and as the emphasis on safety increases it would be inconceivable to use trolley-wire haulage under ground as already witnessed in several other countries with deep coal mines. With rising capital investments and cost of the protection against fire and respirable dust, the use of conveyors may also have to be limited to special areas, e.g. main entries. Indeed, there are only two alternatives available, namely; (1) Degasify the coal seams prior to mining and use conventional electrical power, or (2) Develop alternate sources of power which would be safer and yet efficient and cheap.

Jan 1, 1975

By George J. Karcas

"Non-ferrous metals such as copper, nickel, lead, zinc and precious metals are produced via the electrorefining and electrowinning processes. Apart from controlling electro-chemical conditions for the production of these metals, there has always existed the challenge of controlling the corrosive effect of the electrolyte environment which serves as the medium for non-ferrous metal production.The practice of acid containment in electrometallurgical operations has entered the world of high technology with the advent of advanced acid resistant materials such as vinyl ester resin which is either combined with aggregate to form polymer concrete or used to line various acid containment vessels and ·surfaces. ill comparison to some Asian, European, and African copper refineries, the North and South American copper industry has recently embraced quite heavily in the use of polymer concrete electrolytic cells and process vessels, such as electrolyte storage tanks, and in the use of vinyl ester resin for corrosion protective surface sealing 'systems in lieu of epoxy, acrylic and other materials because of its combination of higher corrosion resistance and superior flexibility.Electrolytic cell construction has undergone a transformation from a multiple part configuration to a single piece moulded/cast unit. ·The one piece moulded polymer concrete cell, which has been patented by Corrosion Technology International, with the overflow, decant, inlet, fast fill and segregation systems integrally designed is now the industry standard.. The combination of a wood, steel, or concrete frame with a lining made of lead, asphalt, rubber or plastic has been historically successful in providing limited protection from chemical and mechanical attack in electrolytic cells and electrolyte storage tanks all over the world. These combinations have now become obsolete as materials such as polymer concrete provide exceptional corrosion and mechanical protection with greatly reduced maintenance requirements and improved efficiency and productivity for the tankhouse. ill addition, polymer concrete can be disposed of in a regular land fIll which is much less costly than disposing of contaminated concrete that is normally associated with conventional lined concrete cells."

Jan 1, 1997

By Daryl R. Tweeton

The Bureau of Mines is investigating possible applications of geophysics to monitor leachate during in situ mining. Tomographic reconstruc-tion of seismic or electromagnetic crosshole data appears applicable. The tomographic program BOMTOM (Bureau of Mines tomography) was written and then used to investigate reconstructions with synthetic travel time data. The calculations confirmed that without constraints, crosshole data do not provide unique solutions. The solution is not determined solely by the data, but is also influenced by the velocity guesses starting the iterative solution procedure. The effectiveness of constraints in combatting nonuniqueness was examined. The requirement that the velocity not vary laterally at the top and bottom of the pixel grid was effective. This constraint is realistic when the top and bottom of the grid represent dry and saturated re-gions, respectively. Limiting the maximum velocity improved reconstructions, but may not be applicable in practice. BOMTOM uses the simultaneous iterative reconstruction technique (SIRT) with straight ray paths. The program is efficient in use of memory, and can be run on a personal computer. A source code in FORTRAN is listed. A source code in BASICA and compiled executable codes in both languages are available from the Bureau's Twin Cities (MN) Research Center.

Jan 1, 1985

By W. H. Miller

Introduction In this paper we have endeavoured to present a general description of the electrical applications underground at Copper Mountain, including types of equipment used, problems encountered, and methods by which they were overcome. No attempt has been made to outline in detail the wiring of various circuits. Until recent years, the main use of electrical energy underground at Copper Mountain consisted of direct current for locomotives, trolley systems, .and signal and communication circuits. The prohibitive cost of equipment and distribution systems prevented any extensive use of a.c. beyond that commonly used for essential lighting purposes. However, in 1943 the shortage of manpower and the increased cost of labour and supplies necessitated a general mechanization programme.

Jan 1, 1951

By John B. Miles

THE present period of depression in the iron industry, with the resultant close approximation of the cost of production to the selling-price of pig-iron, should make the discussion of this subject at this time not only interesting but, profitable. It is possible that it may result, in the collection of data, which when added to those set forth in this paper will clearly indicate the influence of the rate. of driving a blast-furnace upon its fuel-economy. The question is not whether an excessive rate of driving (meaning a rate definitely in excess of the average rate in the United States) results in, an increase in the fuel-consumption, but rather whether a rate considerably less than the average does not result in a marked decrease in the fuel-consumption. The commercial and metallurgical sides of. this problem must be kept separate. With a large margin between the cost of production and the selling-price of pig-iron, and a plant already in operation, it is frequently profitable to sacrifice a couple of hundred pounds of fuel per ton of pig-iron in order to secure the greater gross profits resulting from a larger tonnage. When this margin decreases with a plant in operation, or when the determination of the size of a new furnace intended for a certain production . confronts the management, a clear understanding of the effect of the rate of driving upon fuel-economy becomes necessary. If it be granted that slow driving leads to low fuel-consumption, it should he borne in mind in the design of a new plant for the production of a certain tonnage that the adoption of an economical rate of driving increases only the size of the furnace proper, whereas, due to the decrease in quantity of blast required on account of the decrease in fuel burned, the stoves, the blowing-engines, the boilers and the piping may be de-

Sep 1, 1908

By W. P. Diamond, J. R. Levine

The explosion hazard of methane-air mixtures has become an increasingly serious mine planning problem, and an advance assessment of methane gas potential can therefore be essential for a safe and economic mine development pro- gram. As part of its coal mine health and safety program, the Bureau of Mines has developed a simple, inexpensive test to measure the methane content of coal samples obtained from exploration cores. The gas content of coal per unit weight as determined by the direct method test can be used as a basis for a preliminary estimate of mine ventilation requirements, and to determine if degasification of the coalbed in advance of mining should be considered. Since the Bureau began measuring the gas content of coal samples in 1972, experience has led to equipment and procedural changes, the most significant of which has been the development of a ball mill for crushing the coal sample to release the residual gas at the end of the desorption test period. This revised procedure replaces the crushing box and graphical methods described in earlier Bureau publications. The results of 583 direct method tests are summarized in tabular form. These results include data on the gas content of 125 coalbeds in 15 States.

Jan 1, 1980

By Ronald W. Stingelin

This study undertook the development and implementation of a methodology for estimating the impact of coal seam interaction on the eastern bituminous underground reserve base as published in USBM Information Circular 8655. The effects of previous mining in multiple coal seam areas on currently mined and reserve seams are predicted as a percentage coal loss by an engineering assessment model called the Coal Loss Calculation Model. The model utilizes twelve input variables easily derivable from mine maps or other existing data sources and calculates the effects of subsidence and high-stress due to remnant pillars in the previously mined seam. Extensive literature review resulted in the identification, definition, and quantification of the critical variables of seam interaction. Export opinion surveys were made of mining experts, MESA mine inspectors, and coal mine operators. Statistical analysis was used to establish the redundancy of the critical variables and to develop a total coal loss prediction algorithm. A regional analysis resulted in the production of a series of thematic maps on coal characteristics and distribution. A derivative map showing the areas of commonality within the eastern bituminous coal region served as the basis for implementation of the coal loss calculation model. The model was developed and tested using data from four coal mines in western Pennsylvania and southern West Virginia.

Jan 1, 1976

By Marvin L. Whisman

Several parameters controlling the reproducibility of tritium determina¬tion in organic compounds by liquid scintillation counting were evaluated by the Federal Bureau of Mines. These included optimum volume of scintillator solution for maximum counting efficiency, reproducibility of counting a sealed commercial standard and comparison with duplicate counts on laboratory-prepared samples. The error introduced by using microliter pipets, optical differences in counting vials, reproducibility of counting organic samples where quenching is a factor, reproducibility of counting laboratory-prepared samples with an added internal standard, optimum ratio of internal standard activity to sample activity, effect of sample volume upon counting efficiency, count rate at which coincidence losses become apparent, and reproducibility of organic compound radioassay by the standard addition technique are outlined. From the evaluation of these parameters, a technique that can be applied routinely to organic compounds containing tritium has been established, and details are included in this report.

Jan 1, 1961

By Rejane Tubino Geyer

The volume of electric arc furnace (EAF) plus oxygen (BOF) slag produced yearly in the world is about 84 million ton. Because of this, the study of recycling processes as a way to solve the storage problem of these slags rise in importance. There are, however, some inconvenients on using this byproduct: lime, which takes part of the process of steel production, remains as a non-reactive raw product in the slag. Since lime reacts in presence of humidity, forming expansive compounds, slag use is strongly limited. There are some utilizations for the electric arc furnace and oxygen slag in the Civil Construction Industry, mainly as base, subbase and asphalt covering in highways. However, independently of the type of recycling, a period of "cure" of about six months is necessary. Because of this slow cure process this byproduct may turn non-competitive in some regions if compared, for example, with the natural aggregate. The objective of this work is to present the flowsheet of the slags production as a residue both at the electric and oxygen steel plants and, through a bibliographic review, to analize the possibilities and limiting factors for the use of steelmaking slags in the Civil Construction Industry.

Jan 1, 1996

By G. H. Blackwell

Sequences in open pit mining must be planned and regularly revised to incorporate changes in the variables which affect profitability. Interactive computer planning with colour graphic facilities is an effective tool for this purpose in the short and medium term. An interactive computer planning system for medium-size, low grade porphyry copper-molybdenum open pits is described. The planning system proved especially valuable during the critical stages of pushback mining when deep, inner pit ore was nearly depleted and the erratic grades of the next pushback provided ore and marginal material at a time of depressed metal prices.

Jan 8, 1993

By David Beck

In Australia, Safe Work legislation requires mines to have a documented ‘Safety Case’ explaining how a mine will safely manage all major hazards. A similar requirement is legislated or inferred by regulation in all jurisdictions. For small scale, instabilities leading to day-to-day seismic hazards, a ‘Stability Safety Case’ built around observational methods and measurement triggered responses can be effective because adverse situations are easily identified and the costs of lower control measures are not onerous. Also, if the influence of a volume of yield on the mine load system is small, the response of the system will be more predictable. However, for episodes of large scale mine instability, the hazard derives from the widespread, multi component influence of the event on the mine load system. As the system response depends on interactions between many parts, the resolution of predictions will be lower and situations can arise without local precedent. Further, as episodes of large scale instability change the stiffness and nature of the connectedness between parts of the mine load system, the behavior of the system before the event will be a poor empirical basis for forecasts of event related hazards. Most importantly, Triggered Action Response Plans (TARPs) and ‘traffic light’ warning systems cannot make design choices or identify new hazard phenomena. They are ‘lower’ control measures targeting explicit human-made instability hypotheses. As such, the Safety Cases related to management of hazard from potential large scale seismic events and mine instability cannot rely solely on TARPs. Mines that successfully manage meaningful dynamic instability always acknowledge the ultimate reliance on expert human intuition, knowledge and imagination to appreciate the range of possible hazard scenarios, to make stability hypotheses and propose solutions. Complex analysis, TARPs and measurements are critical steps in the human decision cycle, but only support the making and testing of ‘Stability Hypotheses’ made by expert engineers. Relying on expert skill and judgement as essential components of a Safety Case, however essential, introduces human vulnerabilities. Another challenge is that the expert decision making process is hard to document. Beck et al 2019 first described an organizational and procedural framework for maintenance of an ongoing large-scale ‘Stability Safety Case' where a degree of expert judgement and imagination is needed to manage a seismically active mine. The structured data appreciation process outlined sufficient measurements, analysis and appreciation to confirm the stability state of the mine and was applicable to all underground mines. After several years of implementation in various forms in stoping, caving and room and pillar mines, this update addresses lessons learned and describes some considerations for numerical forecasting to establish a base case, and some challenges for empirical hazard identification.

Apr 26, 2022

By A Tawadrous, D S. Preece

Cave mining is of interest to the mining community as it offers a chance to extract large, deep orebodies with low operating costs and high production rates. It allows for extracting large low-grade orebodies, which may not have previously been considered for mining. Cave mining is done either top down (ie sublevel caving) or bottom up (ie block/panel caving). Both approaches rely on gravity, stresses and weakness of the rock to fracture and achieve a controlled collapse.Block caving starts at the base of the orebody. It progresses upward and across through continuous collapse of the roof. To achieve this, a critical hydraulic radius must be exceeded. This is accomplished by blasting drawbells, through which the caved ore passes to the production level. An entire level above the drawbells (undercut level) is excavated to help initiate the cave. The undercut level ensures the connection between drawbells and achievement of the required hydraulic radius.Conventionally, drawbells are generated by drilling and blasting several times from the production level as well as the undercut level. Mucking between each shot is required to generate enough void space for the rock to swell. The need for several blasts necessitates some downtime between each blast. Also, the cost of developing and maintaining the undercut level can constitute up to 35 per cent of the cost of mining the panel.A new blasting technique was developed to create the drawbells in a single blast from the production level. The technique ensures the connection of the drawbell to the neighbouring ones, thus, the critical hydraulic radius is reached and propagation of the cave achieved without the need for the undercut level. The technique has the potential to reduce the capital cost of a block caving operation, increase its feasibility and reduce time to reach the ore and consequently the payback period. This paper presents the modelling of a traditional drawbell excavation process, the philosophy of the developed technique, the modelling of that new design and its implementation.CITATION:Tawadrous, A and Preece, D S, 2015. A novel blasting technique to create drawbells and eliminate the undercut level in block cave mining, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 617–624 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By T. Dunn

FMC Corporation has achieved a significant cost reduction through a new proprietary solution mining and processing technology at its Green River, Wyoming Soda Ash Facility. In the first phase, completed in October 1995, trona ore is dissolved, recovered and processed with the new technology, and then fed into an existing refining plant, replacing dry mined and calcined trona ore. The second phase, completed in April 1996, produced a fmal high purity product and increased capacity by 635,000 t/a (700,000 tpy). Both phases were completed under budget and well ahead of schedule.

Jan 1, 1998

By K. C. Lahiri, H. P. Das, G. G. Sarkar

"The petrographic components of any particular rank of coal often show some distinct physical and chemical characteristics. Therefore, their pro-portionate distribution in a coal greatly influences the technological behaviour of the coal.In any size or gravity separation of a coal, the petrographic constituents become segregated to different degrees in some preferred size or specific gravity range. Therefore, a knowledge of the petrographic nature of the washed and/or screened fractions is often considered essential in selecting the most efficient method for coal preparation and in exploring the proper evenues for its utilization.A graphical method is described in this paper to indicate the mineral-matter content and the petrographic components of the washed fractions of a coal at different ash levels of separation in the form of a new washability diagram. This diagram can be conveniently used to assess or predict the petrographic composition of clean coal or sinks corresponding to any desired ash level in the cleans. With the help of this diagram, it is also possible to locate the yield level of cleans at which maximum enrichment of vitrinites and exinites occurs with the least amount of mineral-matter content."

Jan 1, 1971

By H. A. Watson

Laboratory tests on three commercial methane detectors, two combustion-type detectors and one interferometer-type detector, were made by the Bureau of Mines to determine their response to certain single and multiple flammable gases mixed with normal and abnormal air atmospheres. Although both types of detectors responded accurately to methane-normal air mixtures, they did not show correct concentrations for other single flammable gases in air. Uniquely, the response of the interferometer-type detector to hydrogen was in a negative direction. The effects of individual gases in multiple flammable gas mixtures were approximately additive. In oxygen-deficient atmospheres the methane response of the interferometer-type detector erred on the high side, but only in very low oxygen concentrations were the combustion-type detectors affected-showing low, erratic methane readings.

Jan 1, 1966

By Giovanni Osellame, Jean Habimana

"The Montreal Metro Blue Line Extension Project is part of a metropolitan Program that was launched in 2009 by the Transportation Ministry of Quebec to add additional extensions to existing metro lines in the cities of Montreal, Longueil and Laval with the intention to meet current demand and future growth within the Montreal agglomeration. Specifically the Blue Line Extension Project will add five underground stations to the East of the Montreal. The paper addresses the preparation and the implementation of a three-step geotechnical and geo-environmental investigation program and preliminary design considerations such as the selection of a preferred horizontal and vertical alignment, the selection of construction methods based on previous local experience and current industry trends, as well as preliminary sizing of underground infrastructures. PROJECT BACKGROUND An agreement between the three mayors of the Montreal Metropolitan City agglomeration, namely, Montreal, Longueil and Laval prompted the Government of the Province of Quebec to create a project office to oversee the studies of extending the existing metro network. The last extension of the existing metro network was completed in 2008 with the Laval extension, which consisted of adding three stations from the existing Orange line. The current extension Program consists of three different extensions, namely extending the Orange Line to Laval and finishing the loop, extending the Blue Line to the East of Montreal by adding five stations, and adding five stations on the Southshore of the St-Lawrence River for the Yellow Line extension. The extension program also requires the construction of an underground storage and maintenance garage located to the north-west of the existing Cote-Vertu station on the Orange line. Figure 1 shows the overall extension program with the existing network."

Jan 1, 2016

By E. M. Murphy

(Presented by invitation at a meeting of the Spokane Local Section of the Institute, Feb. 17, 1912.) EIGHT years ago the Hecla mine, a lead-silver producer, situated at Burke, Idaho, was producing ore from but two levels, the 300- and the 600-ft. All hoisting was done with a 12- by 16-in. slide-valve, double-reel, hoist. The hoist was being worked to its capacity and was unsuitable for hoisting from greater depths. As the work of opening a new level was about to be started, it became necessary to remodel the then-existing equipment or install a new hoist. The recent advent of electricity from Spokane had made available a cheaper power than steam. By a series of tests conducted throughout the Coeur d'Alène district, it was found that it cost $109 per year to generate a horse-power with steam. Electric power was to be had for $50 a horse-power per year. It was decided to substitute for the engines a motor-drive, of sufficient capacity to operate from the 900-ft. level, and ultimately install an entirely new hoist. After disconnecting the engines, installing a new shaft, and making a few minor changes, a 300-h-p., 2,300-volt, 514-rev. per min., variable-speed motor of the induction type was geared to the reel-shaft. The reels were supplied with 3/8 by 4-in. flat rope, and the duty of the hoist was about as follows: Cage, 1,700; ore, 2,600; car, 1,400; rope, 2,250; total, 7,950 pounds. The Bristol ammeter chart, Fig. 1, shows the combined current-consumption of the hoist- and mine-motors. The large intermittent load is clearly shown ; this produced harmful fluctuations in the voltage of the long, lightly-loaded, 60,000-volt transmission-line from Spokane to the Coeur d'Alènes. The power company received no compensation for the increased cost of producing power for this intermittent or fluctuating load. In order to protect its system from similar excessive

Sep 1, 1912

By L. D. Anderson

IN STUDYING Utah as a lead producing state one is immediately confronted by the fact that few, if any, of the ores of the state are valued for their lead contents alone. More correctly the ores from which this metal is recovered are characterized as silver lead. Even then the whole story is not told for many of these ores carry also gold, copper, zinc, bismuth, antimony, arsenic, tellurium, and other metals. It becomes apparent, therefore, that the production of lead i11 Utah is influenced by many factors. For example, i11 the early part of 1923 there was a marked increase in the production of the lead by reason of the efforts made by silver mines to produce as much silver as possible before the termination of purchases under the Pittinan Act in June, 1923. As nearly all silver ores carried more or less lead the production of that metal was increased with the increase in silver production. Very few, if any, ores of the State are mined for their lead contents alone. Important as Utah's contribution to the lead output of the country is nevertheless it is bound up to some extent with the production of gold, silver and copper.

Jan 1, 1925