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By C. Pelley, A. Piche

"The Canadian mining industry faces the prospects of a severe shortage of graduate mining engineers over the next decade. This arises from three factors: first, a growth in industrial activity; second, the average age of company engineering and management staff; and third, the reduced number of students in engineering faculties around the world. This paper aims to identify the critical factors underlying the trend of inadequate recruitment into higher education for mining and to examine means of alleviating the problem.This paper is based upon surveys of potential and current students and graduate mining engineers from four mining schools. An attempt is made to understand institutional and industrial images, career prospects and what is required to attract enough high-calibre young people into mining education over the next decade.IntroductionThe mining industry has started to experience a severe shortage of graduate mining engineers which is likely to persist and even worsen in the short- to medium-term.This arise s from three principal factors:1. a recent and strong growth in mining activity, which surpasses that experienced through the 70s, before the recent international industrial recession; .2. an increasingly older average age of mine engineering employees, at least in the industry's larger companies; and3. problems associated with maintaining adequate mining undergraduate recruitment levels ."

Jan 1, 1989

By D. A. R. Kay

Phase stability diagrams are used to predict the abilities of lanthanum and cerium oxides to desulfurize coal gasification products in the temperature range 800-1000 C. Results of desulfurization studies in laboratory fixed bed reactors illustrate the effects of i) sorbent preparation, ii) input gas quality and iii) temperature, on the desulfurization reaction. 2CeO(2-x)(s) + H2S(g) + (1-2x)H2 = Ce2O2S(s) + 2(1x)H2O(g) The results of desulfurization/oxidation regeneration cycles are also reported.

Jan 1, 1989

By R. S. Dennen

A ground penetrating synthetic pulse radar system has been used by the Bureau of Mines to probe into a coal pillar to locate hidden structures or anomalies. Two types of velocity tomographic reconstruction methods, direct matrix inversion and iterative, were used to obtain a velocity image of the interior of the pillar. The reconstructed image showed the existence and location of a relatively low velocity material within the pillar. Core samples were taken from the pillar in a region surrounding the low velocity material. Analysis of the cores showed the presence of a clay vein coinciding with the low velocity material imaged in the tomogram.

Jan 1, 1989

By Concentrator Staff

"IntroductionA brief literature search will reveal that the information available concerning rod mills and ball mills is quite extensive. This type of equipment is used to treat every element from antimony to zinc. The size and capacity of individual mills, the number of units employed, and the configuration of the equipment within a concentrator add another dimension to the possible scope of this discussion. It would be impossible to treat this volume of material with any degree of thoroughness.It is the intention in this paper to describe the simplest and generally the most typical circuit wherein a single rod mill and ball mill operate in parallel. Some of the subject matter will not be entirely applicable to every installation. However the principles should be generally relevant to most applications.Typical Circuit DescriptionFigure 1 illustrates the arrangement of the equipment associated with a rod-ball mill circuit.Ore is extracted from a fine ore storage bin (1) the capacity of which is large enough to allow .continuous mill operation independently of the mine and crushing plant production schedules. A number of feeders (2) may be employed to control the flow of ore to one or more feeder conveyor belts (3). In larger tonnage operations several such conveyors are employed at least one of which will be equipped with a variable speed control to allow adjusting of the amount of feed reporting to the rod mill. A rod mill feed conveyor (4) accepts all of the ore from these feeder belts for ultimate transfer to the rod mill. This conveyor is normally equipped with a weightometer (5) to monitor the flow rate of ore to the rod mill and ultimately to allow control of this flow. Typically these conveyor belts would be equipped with feed deficiency switches which would give a remote alarm of the fact that no ore is present on the conveyor. The conveyor belts are protected by underspeed monitors which will provide a remote alarm and automatic shutdown of the conveyor in the C'.'~nt that belt slippage occurs. Finally the belts are protected by monitors which will alarm and shut down a belt if it is not running straight in the idlers."

Jan 1, 1989

By Waqinwright M. S

The underlying principles of dewatering theory have recently achieved considerable practical application in the washing and dewatering of alumina trihydrate in Bayer plants. In particular, the influence on residual cake moisture contents of trace amounts of surfactant added to the wash water reveals that significant energy savings can be achieved. The influence of organic compounds produced by the caustic extraction of bauxite in the Bayer process is shown to be significant. These humic species reduce the cake permeability and the effectiveness of certain surfactants in dewatering operations.

Jan 1, 1989

By Jean-Marc Lulin

"Depuis 1906, près de 130 gisements ont été découverts dans la inture archéenne polymétallique (Cu, Zn, Au, Ag) du nord-ouest québécois. Une étude régionale du développement du potentiel inier est présentée puis détaillée pour quatre secteurs: Rouyn-Dranda, Val d'Or-Malartic, Bousquet-Cadillac et Matagami.L' analyse est conduite a l' aide des paramètres suivants: temps, méthodes de découverte, profondeur des gisements et poids métal. Les courbes cumulatives illustrant le nombre de gisements découverts fonction du temps montrent une forme générale en ""S"" dont les i'iations de pentes correspondent aux variations dans les taux de couverte. Initiation, réalisation et stabilisation des cycles de décourté sont ainsi mis en évidence. Deux ""bourns miniers"", de 1922 à 1945 et de 1955 à 1965, rassemblent 72 % des mines identifiées sqú à présent.La plupart des mines sont trouvées en subsurface: 90% ont leur mmet entre 0 et 100 mètres de profondeur dont 70 % entre 0 et 10 êtres. Dans le temps, il y a d' abord récolte par prospection puis par ophysique et enfin, développement progressif du potentiel en proeur avec des méthodes composites. Environ 80% du poids métal extrait de 4 camps miniers, couvrant 8% de Ia surface régionale quelques gros gisements dominent /a production.Ces données permettent de proposer une nouvelle approche pour analyse d' une région minière:La distribution de Ia profondeur des gisements en fonction du temps est indicatrice de la maturité d' un camp minier et peut servir a évaluer son potentiel résiduel.L’analyse des courbes en ""S"" permet d’extrapoler les taux de succès relies aux différentes méthodes et met en relief le rôle crucial de I' innovation dans I' exploration.ABSTRACTSince 1906, some 130 deposits have been discovered in the Archean polymetallic belt of northwestern Quebec. In this paper, the development of the mining potential is analyzed at the regional scale and for the following mining camps: Rouyn-Noranda, Val d'OrMalartic, Bousquet-Cadillac and Matagami.The analysis is based on the following parameters: time, discovery method, depth and weight of metal extracted. Curves showing the cumulative number of deposits discovered as a function of time are ""S"" shaped with slope variations corresponding to changing discovery rates. Initiation, realization and stabilization of discovery cycles are thus well represented. Two ""mining booms"", 1922 to 1945 and 1955 to 1965, account for 72% of the mines identified to date.Most exploitable orebodies have been found near the surface: 90 %have their top between 0 and 100 meters, including 70% between 0 and 10 meters. Early discoveries were made by prospecting, followed by geophysics while the progressive development of the depth potential is being realized by a combination of methods. Approximately 80 %of the metal extracted comes from four mining camps which cover 8% of the area, but most of the production can be allributed to only a few large deposits. Based on these data, a new approach to the analysis of a mining region is proposed:1) The distribution showing deposit depth versus time is indicative of the maturity of a mining camp and can serve to evaluate its remaining potential.2) The ""S"" curve analysis can be used to extrapolate the success rate of a specific exploration method and also stresses the crucial role of innovation in exploration."

Jan 1, 1989

By Theresa M. Bodus

The strength of roof shales is, in part, a function of the preferred orientation of clay minerals within them. Therefore, analysis of clay fabric under both air-dried and hydrated conditions should be helpful in understanding roof shale failure. Core samples were collected from the Energy, Anna, and Lawson shales, which are locally present as roof shales of the Herrin No. 6 coal of southern Illinois. The Clay Fabric Index (CFI) was measured for thirty core samples, using X-ray diffractomtry, to investigate the relationship between clay fabric and roof collapse in coal mines. Greater CFI values indicate a weaker preferred orientation among clay minerals, which generally results in a weaker inter-grain bond. Average CFI values for air-dried samples were: 0.15 for Anna shale; 0.20 for Energy shale; and 0.37 for Lawson shale, .After the introduction of water, average CFI values increased to: 0.28 for Anna shale; 0.22 for Energy shale; and 0.43 for Lawson shale. The laboratory results indicate the following: [l] under air-dried conditions, Anna shale is the most stable, followed by Energy and Lawson shales; and 121 under hydrous (mine) conditions, Energy shale is the most stable, followed by Anna and Lawson shales. In mine environments where roof failures involving Energy shale have occurred, planar trends delineated by a relatively high density of small (0.2-4 cm diameter) iron concretions have been reported along the failure surface. Radial cracks have been observed around unsealed anchor bolt holes in the Anna shale. Instability of the Lawson shale is ubiquitous in coal mines. In the laboratory, similar physical changes were noted in the shale samples after the introduction of water, including [l] increased hydration around the perimeter of iron concretions in Energy shale, [2] radial extension cracks in Anna shale, and 131 extreme slaking of Lawson shale. Measured increases in the CFI reflect the observed physical changes of the samples upon the introduction of water, which probably reflect changes in strength that may result in roof failures in hydrated mine environments.

Jan 1, 1989

By Bryan F. Ulrich

If resin-grouted roof bolts are not installed correctly, mine roof reinforcement can be affected, and roof falls can result. A bolt installation variable that is readily controlled by the mine operator is annulus thickness. The objective of this U. S. Bureau of Mines investigation was to study the effect of annulus thickness variations on the integrity of 3/4-in-diam resin-grouted bolts. Forged-head test bolts, 2 and 1 ft long, were installed in concrete blocks that had been drilled with 1-, 1-1/8-, 1-1/4-, 1-3/8-, and 1-1/2-in-diam bits. Standard pull tests were performed; then the concrete was broken away from the bolts so that grout mix quality could be inspected. It was found that the optimum annulus thickness is 1/8-in (l-in-diam drill hole), and as annulus thickness increases from the optimum, there is a corresponding decrease in grout mix quality, effective grout ratio, and axial stiffness.

Jan 1, 1989

By Bailey JG

There are some thirteen laboratories in Australia in which coal petrological work is carried out on a consistent and routine basis. Applied coal petrological research is conducted by several institutions in different disciplines which can be grouped into four main categories:

Jan 1, 1989

By John S. Timmons, Eivind B. Jensen

The Henderson mine is an underground panel-caving molybdenum mine located in the mountains of central Colorado. All development and primary production operations are performed using diesel-powered, rubber-tired mobile equipment. The growth in manpower and equipment was rapid in the five years following the July 1976 start-up, reaching about 250 machines and 2000 people to produce 9 Mt/a (10 million stpy) of ore. However, due to dramatic improvements in productivity, production is currently at a rate of 8.1 Mt/a (9 million stpy) with about 570 people and a much smaller equipment fleet. The mine's high degree of mechanization and accompanying maintenance costs have focused increased attention on the maintenance function as a cost center with potential for improvement. To realize some of that potential, several approaches to equipment maintenance have been adopted. None of these stand alone effectively, though, and their success relies on their working together in the overall program. The approaches that characterize the equipment mainte¬nance philosophy at Henderson are described here. Preventive maintenance The value of preventive maintenance as an alternative to breakdown or emergency repair is widely accepted in industry. When production began in 1976, few people at Henderson had experience maintaining diesel-powered, rubber-tired equipment. Other company operations such as its previous Urad operation and the Climax molybdenum mine near Leadville, CO used rail and Blusher technology. A maintenance consultant was hired to establish a formal preventive mainte¬nance program. The initial program contained four different preventive maintenance services, "A," "B," "C," and "D." Each was keyed to a different operating interval. • "A" service was the most frequent. It was a quick, general inspection and greasing of all fittings. •"B" service added a more detailed inspection. • "C" service included changing all filters and most fluids, such as engine oil. • "D" service was originally designed as a comprehensive inspection and testing of major component systems over a period of 24 hours during which the equipment was removed from operation. It was believed that most problems uncovered by the inspection could be reported and scheduled for repair at some later date, with only critical repairs being done during the service. In addition to these scheduled preventive maintenance services, a schedlle of minor and major rebuilds at intervals of 2500 to 5000 hours was established.

Jan 1, 1989

By Raimondo Ciccu, Francesco Satta, Marcello Ghiani, Piero Carbini

Nonpolar oils are utilized as collectors in low-rank coals flotation processes. The analysis of the mechanism of the hydrophobic film formation on coal particles permits the identification of the main characteristics that these reagents should exhibit in order to render the process technically and economically efficient. Such requirements - low repulsive energy developed in the interaction with coal particles; limited interfacial tension at the coal-oil boundary; relatively low viscosity and, at the sake time, poor ability to absorb into the coal pores - are found in some binary mixtures of oils having different volumic mass. The features of such mixtures as well as the advantages deriving from their use for the flotation of a Sulcis coal sample and experimentally proven, are described.

Jan 1, 1989

By R. A. Walker, G. Scheltgen, T. Javorsky, G. Blackwell

"Recent engineering advances in open pit rock mechanics have resulted in improved pit wall slope design and improved operating procedures in the event of a major wall instability. At the other end of the spectrum, on the scale of single bench failures, considerable discretion is left to the mine operators as to how potential problems are handled. The usual alternatives are either to operate with caution beneath potential hazards, or try to bring the unstable rock down. In specific cases it may be advantageous to attempt to stabilize rock structures for reasons of access and operating safety.A t the Brenda Mines open pit a prominent structure on the north wall had caused recurring bench-scale wedge failures when exposed on each mining level. In spite of operating precautions a shovel was hit by a rockfall causing significant damage. The first section of this paper describes the investigative, design, and stabilization methods which permitted subsequent mining beneath the structure to proceed without incident. Emphasis is placed on the personnel and equipment resources available at the mine site which were used to minimize costs and which would be available at most operating mines.The second section describes an ongoing research project that utilizes radio telemetry to transmit slope monitoring data. As part of this project the wedge structure was instrumented so that it could be continuously monitored with the aid of a computer. The application demonstrated the potential of 'micro- chip' technology to remote data collection and processing as related to rock structure monitoring, slope stability and safety."

Jan 1, 1989

By Reinhold G. Schulze

Thiourea is being applied as an industrial leaching agent for gold and silver only in a few cases. A GIP technique was developed which eliminates most of the obstacles against its use. Omission of an acid treatment and mild conditions for precious metals stripping from the loaded carbon simplifies process conditions in comparison to cyanide CIP technique. Examples are given.

Jan 1, 1989

By M. Leroux, S. R. Rao, J. Kim, V. Gervais, J. A. Finch, G. Labonté, N. Macminn, M. Ounpuu

Collectorless flotation of sulphide minerals from Lyon Lake ore (Mattabi Mines Ltd.) has been studied both in the laboratory and plant. Among the four major minerals chalcopyrite showed the greatest response to collectorless flotation, followed by galena. Flotation of sphalerite and pyrite was minimal. Collectorless flotation was influenced by pulp potential and pH. Experiments using different gas compositions showed collectorless flotation was promoted when the pulp potentials were greater than about 0 mV (SCE). The study of the effect of depressants showed that SO2 at pH < 8.0 depresses both galena and chalcopyrite but at pH 9.5 flotation of chalcopyrite recovers. Use of NaCN preferentially depressed chalcopyrite compared to galena. Preliminary results from plant tests at Mattabi Mines Ltd. confirm that collectorless flotation occurs and that it is preferential for chalcopyrite and to a lesser extent galena. Practical implications of collectorless flotation in plant practice are discussed. A critical factor will be silver recovery.

Jan 1, 1989

The relationship between the permeability of coal to a mixture of methane and carbon dioxide, and the permeability to methane and carbon dioxide separately is described in this paper, along with the analysis of the differences in permeabilities of coal to methane and carbon dioxide.

Jan 1, 1989

By Clyde Baker

Drilled shafts for many situations offer an economical alternative to driven piles. The Federal Highway Administration (FHWA) has spent considerable time and money in research and developing design and construction guidelines for drilled shafts. However, the full potential of the technology may not be realized because of the uncertainty of the effects of construction on the actual service behavior and the lack of either reliable quality control tests to check for or evaluate defects, or inexpensive load test procedures. Static load testing is very expensive and it is not feasible to load test each shaft on a project. Therefore, other means are necessary to confirm or evaluate the integrity of the completed drilled shaft or to determine the capacity of the completed shaft.

Jan 1, 1989

By Alan P. Prosser

The heap leaching of gold ores by cyanide solution was simulated by computer program. The program uses only basic m1neralogical and chemical data; no process testwork data, such as column leach results, are required. The simulation can be used to forecast the consequences of various changes before and during the testwork, design and operation stages of a particular ore-process system. Also, data about the state of different parts of the heap at various times help create an understanding of what is happening. The effects of mineralogical and process variables on the overall performance of the ?heap leaching process are illustrated. Comparisons are made to column leach tests and production data. The potential of the simulation strategy is discussed for making better use of operating experience and for suggesting specific research objectives. It has become clear that more attention should be paid to other metals that dissolve in the solution.

Jan 1, 1989

By Thomas J. Ferree

"IntroductionThe objective of this chapter is to provide important criteria relating to the operation and maintenance of spiral concentrators and Reichert cones, so that optimum performance can be achieved and maintained in a mill circuit. Little space will be devoted to the theory of the forces of separation or the technical details of the devices, as that in(ormation is available from other sources. The discussions in this chapter will be presented in a manner that should be interesting and useful to anyone who may be exposed to these methods of gravity separation. It is most important for the reader to understand that each application of the equipment should be considered on its own merit, as no two suites of minerals respond exactly alike in mineral processing circuits. The information herein should be useful as a guide toward increasing the metallurgical efficiency of the processes, irrespective of the type of minerals being concentrated.It is highly recommended that certain tools be made available to the personnel responsible for metallurgical performance of the spirals and cones; these include a set of standard type laboratory screens, a medium quality petrographic microscope, and a vanning plaque or gold pan. These devices, when used in conjunction with a basic understanding of the mill circuit, provide immediate knowledge on the characteristics of any sample in the mill circuit. The information gained by visual evaluation of sized fractions of products can solve many of the basic problems of mineral beneficiation, and at the same time increase the interest of the non-technical personnel associated with the plant operation. There are many problems associated with obtaining satisfactory performance from a mill operation. Many of the problems have to be solved using a technical approach. Some of the problems, however, can be solved with practical knowledge and common sense. It is hoped this chapter can provide a guide to both techniques."

Jan 1, 1989

By George A. Savanick

The U.S. Bureau of Mines has patented and transferred to industry an abrasive-enhanced water-jet rock drill. This drill incorporates three novel components: a collimator, jet deflectors for cutting clearance, and an unpressurized swivel, which rotates at 1,000 rpm while passing 20 gpm of an abrasive slurry flowing at 1,000 ft/s. Drilling occurs through the action of a 10,000-psi, 2O-gpm water jet into which is entrained 72 lb/min of abrasives. The pumps, hoses, and fittings are those commonly used in the water-jet-cleaning industry. Only inexpensive, common sandblasting abrasives are used. This drill can cut through hard rocks with moderate-pressure jets; e.g., rocks with a compressive strength of 73,000 psi can be drilled with a 1O,OOO-psi abrasive jet. In addition to drilling holes, the drill can cut deep, narrow kerfs; collar a hole at any angle; drill through rubble; and chamber holes. The development of the abrasive jet drill is a significant advance in the state of the art of hard-rock drilling. The Government of the United States has licensed the abrasive jet drill patent to Weatherford Water Jetting Systems.

Jan 1, 1989

The geographical region of South East Asia is variously defined, but generally agreed to include the Asean group - Philippines, Malaysia, Thailand, Singapore and Indonesia. Other regional countries, such as Vietnam, Laos, Burma, Kampuchea etc. are of course geographically part of the region, however in economic terms, they play a minor role. It is the Asean group that dominates present economic activity and provides the overwhelming opportunity for commercial development. My experience in South East Asia has been gleaned over 15 years of regular travel in the region. More recently, we have established company offices in Malaysia, Singapore and Indonesia to extend and deepen contacts with major customers. This progressive development is an integral part of a planned growth pattern and will be discussed in more detail shortly. South East Asia is a rapidly developing economic growth centre, a fact which is clearly recognised and accepted by most commentators. An important question is then to be asked: Why has the region been relatively neglected by Australian, U.S. and European industrial supply companies? I will attempt to address this question in the context of industrial minerals and propose some ideas as to how effective sales programs could be developed. Firstly, let&apos;s consider the market potential provided by countries within the region. It is reasonable to suggest that industrial growth in S.E. Asia over the past 20 years has been generally steady and in some cases, explosive. Until recently, this growth has predominantly been driven by development of internal (regional) demand. Population growth and rising living standards have ensured that basic industries have enjoyed a solid uptrend in sales and production. The industries which most benefitted from regional economic development over this period were, interestingly, those which we understand to be major users of industrial minerals - glass, ceramics, paper, surface coatings, cement, refractories, rubber and plastics. Each of these industrial sectors has been influenced by different growth stimulii over a 20 year period. Nevertheless, they also enjoy a common feature which ensured an above average performance. All sectors are fundamental to an environment enjoying rising living standards and rapid growth in general prosperity. More recently, internal growth factors have been overtaken by a recognition that manufactured products from the region are competitive in export markets. This comparatively recent development provides the most interesting possibilities for higher value industrial mineral raw materials. Let me explain: For 20 years, industrial growth in South Asia has essentially been focused on satisfying domestic demand. Finished quality of manufactured items was orientated to a developing market more interested in cost than aesthetics or long life. This was reflected in raw material specifications, which often did not exist and at the best were undemanding.

Jan 1, 1989