Search Documents

By Khosrow Badiozamani

Traditionally the mining industry has been lagging in application of computers in their daily or long range plan activities compared to other industries. The question then remains as to how the technology of higher computing capacity for less cost is going to affect the mining industry and how the lukewarm reception of engineers in acceptance of computerized mine planning in the past is going to change because of the new wave of high techology. These questions and the reasons for the lack of usage of computerized mine planning systems by engineers will be evaluated in this paper. In addition, alternatives available to the mining industry will be analyzed and the direction of the future "user friendly" software will be discussed.

Jan 1, 1984

By Frank Lucca

This study is based on a six month study performed for Lee County, Florida. The study was based on blasting for land development and how this type of blasting affects structures. The study is investigates peak particle velocities and the relationship to other environmental and manmade forces that affect structures. The study also explores the effect of geology on blast vibration. After completion in Lee County, the study was then continued in the quarry environment in Vermont and extremely tight blasting environment of New York City. Charge diameters were 127mm (5 inches) or less.

Jan 1, 2006

ESTABLISHMENT of an effective inspection system has been held essen¬tial to any international agreement that may be designed primarily to curb the testing of nuclear weapons. A number of reports and papers already have described basic inspection concepts and appraised various pro¬cedures, techniques, and methods as to their probable effectiveness in detecting and identifying violations under such agreement. This report results from a study of only one part of the contemplated inspection system, specifically the final phases embracing onsite investigations and mine examination techniques. The results and reports of earlier work were reviewed in detail, and subjects that were found to have been exhaus¬tively evaluated are recognized by reference and not redescribed here. In other instances, previously described techniques, methods, and clues were revaluated to define more clearly their practical value to the final objective of an onsite inspection. Previous documentation does not refer to a number of subjects, techniques, tools, clues, and methods considered by the study; this report treats these in detail, even though when applied singly or collectively their practical value may be questionable.

Jan 1, 1962

By Enrique Cervantes

Durante mucho tiempo, las vetas angostas generaron inquietud para los operadores mineros - en tanto su morfología provoca una baja productividad, así como el aspecto técnico obliga a depurar sus sistemas. En ese sentido, el presente texto refiere el método de corte y relleno como el más adecuado para la explotación de vetas puesto que puede adaptarse a las características de este tipo de yacimientos, además del alto grado de flexibilidad para adoptar algún cambio de sistema.

Sep 1, 1982

By Alan U. Seybolt

UNLIKE its sister elements, columbium (niobium) and tantalum, vanadium has not been available until recently in fabricated form. While Vanadium Corporation of America has offered the metal in fairly pure form for sale for many years in small lots for research purposes, this grade of vanadium has been brittle, probably because of a high oxygen content. Hence, when in 1950 the announcement1 was made that wrought vanadium was available as a commercial material, this represented a large step forward in the metallurgy of vanadium. While vanadium is generally regarded as a rare metal, data on its occurrence in the earth's crust show it to be as abundant as copper, zinc, and lead combined. Vanadium is widely distributed, but it does not seem to occur in massive deposits except in a few localities, principally in Colorado, Utah, and Arizona, where it is found in sandstone formations, and in Mina Ragra, Peru. Only in Colorado or Peru are ores mined solely for the vanadium content. Ores in the United States are principally carnotite and roscoelite; the former is of particular interest because of its uranium content. It is a uranium-potassium vanadate containing approximately 52 pct of UO2 and 18 pct of V2O5. Production in the United States during the war years averaged around 2000 tons a year, but dropped to 636 tons in 1946. In recent years, ferrovanadium has been selling for about $2.80 per pound of contained vanadium. This suggests that the price of the pure metal will never be as low as $2.80 per pound, but it could

Jan 1, 1953

By Hayward N, Sutherland D, Wilkie G

A pilot plant study has been made of the liberation characteristics of a nickel ore under different milling conditions. A series of runs were made ranging from fully autogenous grinding to semi-autogenous grinding with a ball load of 8%. The mill products were sized and assayed then analysed by QEM4SEM. This enabled a full liberation analysis to be carried out to see whether the autogenous grinding leads to improved liberation by promoting selective breakage. Though it is frequently claimed that fully autogenous grinding yields superior liberation this could not be detected in the present study.

Jan 1, 1991

By B Wiggins, M Russell

Off-gas handling systems are a critical component of modern metallurgical furnaces and typically represent as much as 50 per cent of the total installed smelter capital cost. Inadequate off-gas system performance, due to insufficient exhaust flow or excess maintenance downtime, can present a serious process bottleneck and limit smelter production rate. Therefore, it is essential that the relevant performance issues are fully understood and considered in the design of these systems, particularly when combustibles produced within the furnace must be combusted or handled in the off-gas system. This paper examines the requirements, design issues, and conceptual design process for state-of-the-art postcombustion off-gas systems. The relevant design considerations of safety, environment, energy consumption, and maintenance are presented, and the relative importance of these key issues are compared and discussed. The benefits of using computational fluid dynamic (CFD) modeling in the design process at the conceptual design stage are also demonstrated. Finally, the design basis and performance of a recent Hatch-engineered system currently in operation is evaluated.

Jan 1, 2002

By L. B. Clarke

The optimal maintenance and control of the air flow and pressure distribution in a mine network are achieved by the correct positioning of the mine fans and regulators within the mine ventilation circuit. The principal considerations are the location of the main and underground fans or regulators and the attendant control of mine leakage. Air flow control is achieved by either passive or active regulation. Passive regulation adds resistance, usually in the form of a regulating door. Active regulation adds pressure sources in the form of underground booster fans. Ventilation engineers are increasingly turning to analytical tools to assist them in the design and operation of ventilation systems. The application of computer methods, formal optimisation methods and numerical solution methods is outlined

Jul 1, 1996

By F. Weinberg, L. MacAulay

DAVIS,' in an investigation of solute redistribution along molten rods of dilute silver in tin, concluded that at horizontal temperature gradients below approximately 5°C per cm very little convective mixing takes place. Cole and winegard2 observed temperature oscillations in horizontal melts of tin, with temperature gradients of several deg per cm. They associated the temperature oscillations with the presence of convective flow in the melt. At temperature gradients less than 1°C per cm they did not detect convective flow. In the present work, direct measurements of con-vective flow in liquid tin have been made using a radioactive tracer technique. The results indicate that extensive convective flow occurs at temperature gradients below those previously reported. The apparatus used to determine the extent of con-vective flow is shown in Fig. 1. The graphite boat Fig. l(a), has two rectangular channels both of which contain molten tin. Radioactive Ag110 in the form of Sn-0.2 pct Ag alloy was introduced at the end of one channel, by rotating the cylinder shown. A series of fixed thermocouples were positioned along the center of the second channel to determine the temperature gradient. It was assumed that the two channels had identical temperature distributions. The graphite boat was inserted into a vycor tube which was surrounded by a multiple winding tube furnace as shown in Fig. l(b). The tin was melted in an argon atmosphere. The distribution of Ag110, as a function of position along the boat at a given time after introduction of the ~g"', was determined with the

Jan 1, 1970

By P A. Gibson, J R. Brinkmann

The South African gold mining industry fires approximately 800 000 sloping blastholes daily. A programme aimed at characterizing the stope blasting process is underway in order to identify areas for improvement and to provide blasting related information for the design of mechanized sloping systems.

Jan 1, 1985

By H. Scott-Russell

Ladies and Gentlemen. It is my great pleasure on behalf of The South African Institute of Mining and Metallurgy and The Geological Society of South Africa to welcome you to the 15th CMMI Congress and to Southern Africa. It is a great honour to be hosting this event and we have been looking forward to it for a long time. I am sure the technical discussions and visits will be of great value, and I am confident you will return with pleasant memories of places and people in South Africa and neighbouring countries. The theme of this Congress, Resources and Technology', is appropriate for discussions on the ways and means of going forward in the minerals industry to create the employment and wealth so sorely needed in this region. The technical programme will give mineral industry professionals from different parts of the world the opportunity to share experience and expertise for the purpose of making operations more productive, safer and environmentally acceptable to the world at large. Delegates will be exposed to current technical developments by means of 133 papers prepared for the congress: 30 on geological subjects, 45 on mining, 29 on extractive metallurgy, and 29 in the field of metals technology.

Jan 1, 1994

Develop a full-length-anchored roof bolt that is economical, nontoxic, nonflammable, and non-allergenic. Approach Grout roof bolts with a storable mixture of ultra-fast setting inorganic cement and water. How It Works A loose mixture of dry cement powder, and pinhead-size water droplets encased in waxy globules, are pack-aged in sausage shaped cartridges for storage and use. After the cartridge is inserted Into a drilled hole, the roof bolt is thrust In and rotated to mix the cement and water. The cement hardens in seconds, providing usuable anchoring strengths in minutes. Prior to filling of the sausage shaped cartridges, the microcapsules of water are Intimately mixed with the dry cement. The currently used grouting consists of a mixture of one part water (minimum) with three parts alpha-type gypsum cement and a minor amount of accelerator.

Jan 1, 1978

By J. J. Demeter

Experiments were conducted in 2- and 4-inch-diameter standpipes to evaluate the effectiveness of standpipes as pressure seals. During the experiments, these standpipes conveyed Alan-Wood magnetite (60 to 230 U.S. standard sieve mesh) by gravity flow from one vessel to another of relatively higher pressure. The information obtained has been helpful in a Federal Bureau of Mines investigation of how to make either synthesis gas or hydrogen by a modified steam-iron process employing a continuous recycling stream of granular iron-iron oxide at temperatures of 600° to 900° C. In this process the mixture of granular material flows by gravity from a reduction vessel at low pressures to an oxidation vessel at higher pressures. Data from the 2- and 4-inch-diameter standpipes indicate that it would be practical to use a standpipe as a pressure seal between the reductor and oxidizer. Investigators found that, by gravity flow, the standpipe could convey the Alan-Wood magnetite against pressure gradients up to 1.07 pounds per square inch per foot of column height.

Jan 1, 1961

By Ryan CG, Cousens DR, Griffin WL

The proton microprobe is developing into a vital tool in the geosciences, through its high sensitivity for in-situ detection of trace elements in the ppm regime. This paper will describe the instrument at the CSIRO Heavy Ion Analytical Facility at North Ryde, including features crucial to its successful application in the geoscience. Examples of applications in the basic geoscience and mineral industry related research are described briefly. Conditions required for widescale applications in the minerals industry are Discussed.

Jan 1, 1989

In 1980 Pancontinental Mining Limited decided that while the Jabiluka uranium project was still a major focus of the company's efforts some diversification was necessary. At this time it was decided to include precious metals in Pancon's exploration and acquisition objectives. As a result the now Paddington Gold tenements were acquired, explored and developed. Today, it rates as the 6th largest gold mine in Australia and at an expanded throughput of 1.2 million tonnes per year of ore it will produce about 110,000 ozs of gold per year. Following extensive exploration activities by Pancon's Exploration Division the Operations Division continued with development drilling finally proving up a reserve of about 8.4 million tonnes at an average grade of 3.2 g/t. An in- house preliminary feasibility study was followed by a two phase feasibility study by Davy McKee. This resulted in a recommendation to the Pancon Board of Directors to develop Paddington with an annual throughput capacity of 875,000 tonnes. This paper describes the acquisition, exploration and development of the Paddington project. It goes on to

Jan 1, 1986

Sluice box operating practices in Papua New Guinea (PNG), and published work on sluice boxes are briefly reviewed. Some recent work on sediment entrainment mechanisms occurring in sluice boxes have also been described. In the light of this information, some drawbacks in the commonly adopted sluice box operating practices in PNG, and ways of overcoming them, are also highlighted.

Jan 1, 1991

By S. F. Ramseyer, E. A. Steigerwald

INFILTRATED structures represent composite materials which are capable of combining high-temperature strength with adequate low-temperature toughness and thermal shock resistance. Although copper- and silver-infiltrated tungsten structures are actually being used in rocket nozzle hardware, adequate understanding of the fracture mechanics of these composite systems is not available. Specifically the relative importance of the strength, ductility, and modulus of the infiltrant in determining composite properties is not known to the extent that optimum composites can be selected. The major portion of experimental effort in the area of composite strength has been devoted to fiber-reinforced systems1 or to systems where a discontinuous phase is imbedded in a relatively ductile matrix.2'3 In the case of high-temperature systems, which are composed of a relatively brittle matrix, such as tungsten or an oxide, a continuous phase exists for the propagation of a crack. The method by which the presence of a conjugate ductile continuous phase influences the gross properties of the composite represents an area which requires further investigation. This technical note presents results which evaluate the effect of infiltrant strength on the strength of the tungsten-base composite. A tungsten matrix and copper-base infiltrant were selected for the initial studies because of the ease of fabrication. Tungsten structures with nominally 20 and 30 pct porosity were evaluated. The porosity was controlled by varying the initial powder size and a ratio of open-to-total porosity greater than 95 pct was obtained by selective sintering cycles. The processing sequence involved hydrostatic pressing followed by a 72-hr presinter in hydrogen at 2000° F and a final sinter at 4000°F for 4 hr in vacuum. The 20 pct porous structure was obtained

Jan 1, 1965

By C. B. Murray

"OUR experience from time immemorial has been that the furnace sampler and analyst usually find one or two, and sometimes more, points less iron than the Lake Superior shippers, but, fortunately, their contracts are `iron bound'; and, generally speaking, analyses at this end are practically useless, for we are obliged to settle on basis figured out to a half dozen decimals, and, as a rule, without recourse in the event of flagrant discrepancies between the two analysts." The above is an extract from a letter received by the writer of this paper from the President of an iron company, discussing the question of sampling. It so well expresses the opinion of many blast-furnace owners and managers that it seems a suitable text for a discussion concerning the need of uniform methods of sampling. If all railroad cars were loaded the same, if all stock piles were the same shape, and if ore was received regularly each day, the problem of sampling would be comparatively simple. The conditions, however, vary widely at different places, and at the same place from day to day, and it is probably impossible to determine upon any one method of sampling which will apply at all times and in all cases. However, it would seem as though some general principles might be suggested which would tend to overcome these wide differences in samples of the same thing. The sampling of a cargo of iron ore begins at the breast of ore in the mine. The ore is sampled from the mine cars, from the stock piles, and from the railroad cars at the mines. At the lower Lake ports the ore is practically all sampled from the boat, occasionally from railroad cars. At the furnaces, the ore is nearly all sampled from railroad cars and occasionally from stock piles.

Jan 1, 1914

By T. A. Rickard

The purposes of composition are various; one purpose, for instance, is to make a record for the writer's own use, as in a diary. That does not involve responsibility to others. There is also the writing meant to influence opinion-to be persuasive, and pleasing. With such writing we need not concern ourselves at this stage of our study. The prime purpose of technical writing is to be informative-to convey information; therefore it must" be clear beyond the chance of misunderstanding. Such clearness is impossible if meaningless or ill chosen, words are sprinkled through the text. Discard the trivial phrases that are constantly at your elbow. Brush aside a host of vapid superlatives. Metternich exclaimed:' "The superla¬tive is the mark of fools". It is a false emphasis, like the underlining in a school-girl's letter. For example, the little word `very' can be deleted nine times out of ten; it is an impediment to terse and perspicuous writing, as 'the multitudinous hand-baggage of the British tourist is to his travel. 'Very' supposes comparison. A mine with a 1000-ft. shaft is very deep to the scribe who writes from the Joplin district', in Missouri, but it seems a shallow hole to a man living at Calumet, Michigan. A vein that is 10 feet across may be considered very wide at Cripple Creek, Colorado, but it is only a `stringer' to the miner at the Homestake, in South Dakota. Ore assaying $20 in gold is very rich at Juneau, Alaska, where .10,000 tons of $1 ore is crushed daily, but it is relatively low-grade to the pocket-miner at Alleghany, in California. It is all a matter of comparison; unless the reader knows your standards of depth, width, or richness, your `very' has no significance. "Where erosion was very rapid or oxidation very shallow"

Jan 1, 1931

By J. W. van der Merwe, A. S. Bolokang, M. J. Phasha, V. J. Matjeke, C. Moopanar

"Excessive wear rates on railway wheels can result in rolling-stock derailments. If wear is detected early the possible derailments can be prevented by prematurely replacing wheelsets, although the inventory cost and maintenance downtime remain a challenge. In the current study, wheels were introduced and monitored in-service for two years to investigate the cause of excessive wear rates. The wear rates and stresses were calculated for the wheels suitable for a maximum load of 26 t per axle. Microstructural and mechanical properties were analysed. As expected, the general microstructure of all the wheels tested was pearlitic. Although all the wheels complied with the tensile strength requirements, stress calculations confirmed material distortion on excessively worn wheels whereas trial wheels revealed yield strength exceeding the yield criterion. High wear rates observed on the wheels were a result of low yield strength relative to the load per axle. The typical wear mechanism found was due to a combination of rolling contact fatigue and abrasive brake wear. Despite compliance of the wheels with existing requirements regarding material and mechanical properties (hardness, ultimate tensile strength), it is recommended that the yield strength must also be taken into consideration as a critical parameter.IntroductionRailway wheels are used to support the wagon mass and guide the wagon along the tracks (Park, 1974). The wheels and rails must be able to tolerate the applied tangential forces in order to effect wagon dynamic performance and reduce material deformation (Ghidini et al., 1994; RSE_TE_SPC_0045, 2011; AAR M107/M 208 Specification, 2011. Over the past ten years, the South African coal wagon maintenance depot has experienced excessive hollow wheel wear rates on the heavy haul line wheels. The maximum load of Jumbo wagons on the coal line is 104 t, or 26 t per axle. Although the maintenance intervention cycle for wheelsets was two years, between February 2011 and August 2012 some wheels experienced excessive hollow wear. Hollow wear is regarded as wear exceeding 2 mm on the central portion of the wheel tread (RSE_TE_SPC_0045, 2011). This happened despite the fact that these wheels were manufactured and certified according to the requirements of AAR M107/208 standard for carbon steel wheels (AAR M107/M 208 Specification,. 2011) and the local wheel RS/ME/SP 021 standard specification (RS / ME / SP / 021 REV 5 (2013). The AAR standard only specifies a minimum hardness as a required mechanical property and the local standard specifies hardness and minimum tensile strength only. In general, an increase in hardness will improve the rolling/sliding wear resistance of steel. This relationship of hardness and wear resistance was found to be true only in a situation where solid and similar alloys are in contact (Singh, Khatirkar and Sapate, 2015). The sliding wear resistance of a material is usually estimated using Archard’s equation (Liu and Li, 2001)."

Jan 1, 2016