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By R. L. Grayson

The health and safety of employees, efficiency of the operating system and production are paramount goals in underground coal mining. The section foreman assumes responsibility for making his part of the total system function to meet these goals. However, section foremen often have not been prepared to assume the full range of their responsibilities upon becoming a supervisor. This discussion addresses the full range of section foreman responsibilities and concomitant authority. Management principles that must be mastered by him are presented, and performance expectations as well as criteria for their evaluation are examined. The benefits realized from effective foreman training are discussed.

Jan 1, 1985

By Murray Pezim

In the good old days of the folklore of the mining industry, grizzled prospectors obtained a few loose dollars from friends and neighbours then wandered off to eventually return with the great discovery which became the core of the new corporate empires. Alternatively, merchant banking barons obtained exclusive rights to just about anything of future value over hugh nation-size territories. Some of this probably still goes on, likely with about the same ineffectiveness and waste of effort and money as in the past. CURRENT CONCERNS IN MINING In today's difficult climate in the mining industry, for that matter in all industry, effectiveness is the vital consideration. Cost effectiveness -- more bang for the buck -- is especially important in such an area of high risk as mineral exploration. And there are other factors to consider. Since minerals are depleting resources, the mining inddustry is constantly confronted with the reality that those resources extracted today must be immediately replaced if a resource enterprise is to continue. And if growth is to be achieved, even more resources must be found to support future expansion. The current and immediately foreseeable climate internationally for the mining industry creates a special need and urgency for aggressive and successful exploration, certainly in Canada, if not also in the United States. Depressed world markets and prices have turned yesterday's economic reserves into today's waste, hopefully to be converted into economic ore again in some distant time. One way of replenishing reserves and maintaining a viable mining industry is to find and develop mines which are economic under short-term depressed price and market conditions. This probably means higher grades. A new copper discovery with the right combination of characteristics to be an attractive investment even at today's pices for copper would still merit development into production. Exploration is the only way to find such mines for the difficult short-term conditions. Another important consideration is that normally many years stretch from the first thought of conducting exploration to production -- in those rare instances where an economic discovery is made. If discoveries are not made today, then there will not be any projects to develop when business conditions are more attrative. This industry and the vast number of skilled professionals who are part of mining, are faced with two key problems that underlie the need for a junior exploration segment. One consideration is how to maintain exploration during those years, indeed eras, of recession and depression. We are in such a time now. Throughout the world, major companies have sharply cut back, if not eliminated completely, exploration expenditures other than what is vitally necessary and easily and inexpensively done at the known and producing deposits. And related to that consideration, even more important today than during happier times, is how to finance such necessary ongoing exploration if major companies and governments back away because of financial stringency. CANADIAN SUCCESS In Canada, such problems are being tackled with a success which is capturing worldwide attention. The ability of mineral explorers to obtain willing, eager, high-risk capital is achieving even more outstanding results than in the past. These results are reflected in the widespread continuing exploration ativity in Canada which even spreads into the United States, with some outstanding discovery successes. The most notable exploration success from junior mining activity is the discovery of the Hemlo gold camp in northwestern Ontario, a source of gold which promises to rank with the South

Jan 1, 1985

The society in which we live is one of change, and we professionals are part of that society. The importance of this simple and obvious statement is often overlooked. My Presidential Address examines the question: can professionalism survive in our changing society?There is ample evidence to show that our society is changing, and that the rate of change is exponential. This rapid and accelerating rate of change is what Alvin Tomer refers to as "future shock". Rapid change means that we do not have time to become accustomed to what is happening around us and to feel comfortable with it; the greater the rate of change the greater the discomfort. The effect that this has on people is varied; the change may be either expected or totally unexpected.The rate and extent of change in society is not the same for all countries nor for all industries or occupations. Change is more rapid in Japan, Korea or Taiwan, than in Australia. It is more rapid in our cities than in the bush, more rapid for professional businessmen than for farmers. In our minerals and petroleum industries, we are still adjusting to the great changes that have taken place over the last fifteen years. In the past, products from our industries were sold on a free and open market. Today, mineral development and production in most undeveloped countries and some developed countries is manipulated for political, social and economic reasons. Changes of this nature have had a devastating effect on the operations of established mineral producers in the democracies.Because of the accelerating nature of change, we must recognise that the past is not a reliable guide to the future.Although extrapolation of the past into the future is a basic ingredient of commercial survival, extrapolation is less and less reliable.I borrow from others in quoting the Irish proverb: "The future is not what it was".The future is where our business lies and most of us at this Conference must endeavour to understand it and adjust to it. I believe in the old adage that:You can't know where you're going if you don't know where you've been and where you are at.There are a number of major factors which have created change within our social, economic, and industrial environment in recent years.

Jan 1, 1985

By Robert L. Voss, Richard D. Hagni

Sparry dolomite from all of the operating mines in the Viburnum Trend of Southeast Missouri have been found by cathodoluminescence microscopy to reveal a systematic pattern of banding resulting from a growth zoning within individual dolomite rhombs. Four principal bands have been recognized throughout the entire Trend and each of the major bands contain even finer internal banding. Minor bands a few microns in width can be correlated in specimens collected ten's of kilometers apart along the trend. The first three principal dolomite bands decrease from south to north. This feature, together with the fact that the white sparry dolomite crystals decrease in abundance from south to north in the Trend, suggests that a major source for the fluids was from the south. The application of cathodoluminescence microscopy to crystalline dolomite demonstrates a strong correlation between ore grade and the intensity of internal banding and dissolution textures.

Jan 1, 1985

By Michael J. Klishis

It was the goal of this project to develop training materials specific to two areas of the mining industry: (1) safe use and care of the self-contained self-rescuers, and (2) awareness and avoidance of electrical hazards. This report describes the development of the following training material: Instructor's modules for the OCENCO EBA 6.5, CSE AU-9A1, and PASS 700E self-contained self-rescuers; and a textbook, slide tapes, and accident case study scenarios for mine electricity, and a computer based instructional package on mine electricity and electrical hazards. The report concludes that additional efforts are needed in mine training and four recommendations are made: (a) tailor existing materials to fit specific mine sites, (b) develop and evaluate computer based instructional material, (c) develop parallel training materials for metal and non-metal mines and, (d) develop additional training materials for preparation plants and surface areas of underground mines.

Jan 1, 1985

By Moorrees C, Koh P. T L, Tsambourakis G

Examination of Ihe calcination and carbonic acid leaching behaviour of a number of Australian magnesites shows that there are substantial differences between the massively crystalline and the cryptocrystalline forms of magnesites. Crude magnesias formed by calcination of the massive variety of magnesite have considerably smaller surface area and show lower rates of reaction with carbonic acid when compared With those derived from cryptocrystalline magnesites. In order lO producc a rcactivc magncsia from massive magnesite, the calcination conditions must be carefully controlled over a narrow temperature range (eg 680-720°C). For the cryptocrystalline calcines, the temperature of formation has little effect on reactivity.The results confirm the general applicability of the calcination/carbonic acid leach process for producing magnesia from magnesitc. If a mixed crystalline/cryplocrystalline feed is to be processed, then processing conditions must be optimized in terms of the behaviour of the crystalline component of the feed.

Jan 1, 1985

By W. C. McBee

Technology for the preparation of densifiable sulfur concrete (sulfapave) materials has been devised by the Bureau of Mines. The materials are intended as new construction materials for use in corrosive areas where conventional materials fail. A series of modified sulfur cements were developed, which can be used in combination with dense-graded aggregates to prepare sulfapave materials with excellent corrosion-resistant properties. The materials can be mixed, laid, and compacted into place with conventional hot-mix asphalt pavi.ng equipment. Mixture designs utilizing 5-to 30-pct-modified sulfur cements and dense-graded aggregates gave material properties ranging from rigid to flexible. Laboratory corrosion tests in sulfuric acid showed no material loss or deterioration of physical properties over a 1-year test period in concentrations ranging from 0 to 60 pct at ambient temperatures. Preliminary results on field testing the materials for durability to weathering, corrosion, and traffic have been excellent, with no evidence of failure in the materials.

Jan 1, 1985

By Davies S. G, Jayaweera A

The oxidation of nickel sulphide and copper sulphide concentrates, and coal, has been studied under non-ignition and ignition conditions using Differential Thermal Analysis (DTA) and Thermogravimetry (TG). The non-ignition reaction was favoured by slow heating rates < 10°C min-1), low masses < 10 mg) and an air atmosphere. Under these conditions, the typical stepwise oxidations of the various sulphide minerals present in the concentrate were observed as resolved exothermic peaks in the DTA curves and weight losses in the TG curves. Above a heating rate of 10°C min-1 , sample masses in excess of 10 mg and an oxygen atmosphere, an ignition reaction was induced, as indicated by a major high energy exotherm in the DTA curve and a major rapid weight loss in the TG curve. The ignition temperatures of the minerals under ignition conditions, found for 15 mg samples heated at 20°C min-1, were 434°C for the nickel sulphide concentrate, 372°C for the copper sulphide concentrate, and 230°C for the coal. By plotting a curve for mass against ignition temperature at constant heating rate and extrapolationto zero mass, a value of 470°C was obtained for the mass independent ignition temperature of the nickel sulphide concentrate. Ignition temperatures and extents of reaction at various temperatures were obtained using the TG technique in a novel manner which produced heating rates of 4500°C min-1. Under ignition conditions, the oxidations approximate to flash smelting conditions.

Jan 1, 1985

By H. B. Oblad

Coal/pyrite fines were froth floated in a laboratory cell to examine the rate of pyrite recovery during conventional coal flotation. The effects of collector, particle size and carbon to total sulfur ratio on the kinetics of recovery were investigated. These data coupled with microscopic examination suggest that miniscule amounts of coal that remain attached to the pyrite surface affect the rate of flotation of pyrite.

Jan 1, 1985

By L. E. Schultze

The Bureau of Mines devised a technique to recover a Zn-Pb concen-trate from a geothermal brine. More than 99 pct of the Zn and Ph was precipitated by treating the brine with H2S and controlling the pH with lime. Recycle of the sulfide precipitates increased crystal size and resulted in easily filterable products. A typical sulfide precipitate contained 53 pct ZnS, 8 pet PbS, 24 pct MnS, and 15 pct FeS. Addition of sulfide as FeS or CaS was not effective in precipitating Zn and Pb, but Zn in the brine was selectively removed with a strongly basic ion-exchange resin. A proposed flowsheet for metals recovery is discussed.

Jan 1, 1985

By K. N. Han

Coal is becoming increasingly important as a major energy source in the face of the world's depleting energy mainly based on oil reserves. Coal is by far the most abundant fossil fuel both in the United States and abroad. Currently, because of increased mine mechanization, the fineness of preparation plant feed is increasing. Further, in the future as the grade of coal diminishes and the sulfur content increases, upgrading preparation of coal is very important. Because the density of coal is less than that of rock materials that occur as impurities, coal is separated from such waste largely by gravity-controlled processes for particle size between 5 inches and 28 mesh. If the size of coal particles is below 28 mesh, froth flotation is a good method for upgrading fine coal. Previously, numerous investigators have tried to upgrade coal values by froth flotation(1-16) and have achieved moderate success. However, the recovery and grade of coals in the concentrates are not always satisfactory, especially when the particle size is small. In general, when the size of coal is below 100 mesh, the above methods suffer from poor grade and low recovery. The reason for this is that as size decreases, the effects of gravity diminish, and other forces take effect.

Jan 1, 1985

By Reed S. C. Rogers

The breakage parameters of phosphate ore were determined by batch first-order grinding studies in a laboratory ball mill according to the procedures described in the text by Austin, Klimpel and Luckie, using a slurry density of 70 weight percent. The results were scaled to five larger mills of 0.56 m diameter by 0.91 m length (2 ft. by 3 ft.), 0.82 m by 1.52 m (3 ft. by 5 ft.), 3.36 m by 7.90 m (11.5 ft. by 25 ft.), 4.41 m by 9.10 m (14.5 ft. by 30 ft.), and 5 m by 11.1 m (17 ft. by 36 ft.), assuming equilibrium ball charges for the full-scale mills. The results were used to predict product size distribustions and capacities for batch grinding in the 0.56 m and 0.82 m diameter mills and open circuit grinding in the 0.82 m diameter and larger mills using a one-large/two-small reactors in series model fitted to the residence time distribution measured in the 4.41 m diameter mill. The simulated results were compared to plant data for ranges of mill capacities. It was found that the simulated product size distributions were in good agreement with the experimental values below the 70% passing sizes, but did not agree so well in the top sizes. The predicted capacities were in approximate agreement with experimental values for the pilot-scale mills, were about 7 percent too high for the 3.36 m and 4.41 m diameter mills and about 25 percent high for the 5 m diameter mill. Use of the Bond method with the measured Work Index of the phosphate ore gave capacity predictions that were 45 to 150 percent too high.

Jan 1, 1985

By Jon C. Volkwein

The Bureau of Mines, Foster-Miller Inc., and Beaver Creek Coal Co. have evaluated the ability of a new system to ventilate a 40-ft-deep cut. A remote-control continuous-mining machine, in a 7-ft-thick seam, with exhausting brattice was fitted with an improved sprayfan system plus additional forward and reverse pointing sprays. Static and dynamic tests using tracer gas were conducted in a full-scale model and under-ground to measure the effectiveness of exhaust face ventilation for various deep-cutting mine and spray configurations. When compared to a lO-ft primary ventilation brattice, the extended-cut spray system consistently provided better face ventilation at all configurations up to and including a 40-ft brattice setback. The system also provided good dust protection and visibility for the machine operator. Another safety advantage is the elimination of the need to set temporary roof supports to maintain the ventilation brattice.

Jan 1, 1985

Develop improved blasting practices that can help to curb overbreak in highwalls at surface mines, thereby reducing the hazards of rock-falls to workers and equipment, The Problem The serious hazard in surface mining is the falling of rock from highwalls. Poor highwall stability is caused in part by geologic conditions, but often is aggravated by faulty blasting practices, where the explosive energy not only fractures the rock to be excavated, but also damages the rock that borders the excavation. This reduces the general stability of the hlghwall and increases the rockfall potential. The probability of injury to mine workers or damage to equipment associated with exposure to the highwall increases with the height of the highwall and the extent of its overbreakage. Most rockfalls occur in the first 15 days after a new highwall is exposed. This statistic is significant since most of the work below a highwall is done during this period. The area of greatest hazard is within 25 ft of the toe for rocks that fall vertically, and up to 90 ft from the toe for falling rocks that are deflected by the highwall during their descent, The workers most frequently involved in such accidents are dozer operators, ground laborers, and shovel operators or oilers.

Jan 1, 1985

By Mark S. Stagg, David E. Siskind

The Bureau of Mines arranged to have a wood-frame test house built in the pat of an advancing surface coal nine so it could investigate the effects of repeated blasting on a residential house. Structural fatigue and damage were assessed over a 2-yr period. The house was subjected to vibrations from 587 production blasts with particle velocities that varied from 0.10 to 6.94 in/s. Later, the entire house was mechanically shaken to produce fatigue cracking. Failure strain characteristics of construction materials were evaluated as a basis for comparing strains induced by blasting and shaker loading to those induced by weather and household activities. Cosmetic or hairline cracks 0.01 to 0.10 mm wide occurred during construction of the house and also during periods when no blasts were detonated. The formation of cosmetic cracks increased from 0.3 to 1.0 cracks per week when ground motions exceeded 1.0 in/s. Human activity and changes in temperature and humidity caused strains in walls that were equivalent to those produced by ground motions up to 1.2 in/s. When the entire structure was mechanically shaken, the first wallboard tape joint crack appeared after 56,000 cycles, the equivalent of 28 yr of shaking by blast-generated ground motions of 0.5 in/s twice a day.

Jan 1, 1985

By I. Iwasaki

Precious metals are commonly believed to be recovered along with sulfide minerals in flotation, but a few neutron activation analyses showed that the recoveries of gold and silver were unexpectedly low. Recoveries of platinum group metals remained unresolved due to interferences in the analyses. Electron micro-probe, scanning electron microscope and scanning auger microprobe analyses have identified nickel arsenide minerals in the ore and confirmed a close association of platinum group metals with the arsenide minerals as minute inclusions. These results indicated a need for re-evaluation of flotation procedures which have so far ignored special problems related to arsenide minerals. The electrochemical and flotation behaviors of nickel arsenide and their implications to the flotation recovery of arsenide minerals from copper-nickel bearing Duluth gabbro are presented.

Jan 1, 1985

By W. M. Scheding

"There has recently been a resurgence of interest in unit flotation of mill discharges. At the Kidd Creek concentrator, this technique has been successfully applied to silver flotation in a 3050 mtpd silver-copper-lead-zinc division. The major incentive has been improved silver payment through increased overall recovery and better distribution between the sequential copper, lead and zinc concentrates. A large, but variable fraction of the silver in the ore is present as native silver and, being dense and malleable, is susceptible to overgrinding. Grinding circuit surveys showed high concentrations of silver in both primary and secondary circulating loads. Laboratory testwork confirmed that this was selectively flotable, identified the secondary ball mill discharge as the best feed stream and optimized flotation conditions. A 10 t/h pilot plant campaign confirmed that the rate of accumulation of silver was sufficient to sustain continuous production of a silver concentrate and that flotation of the whole stream was not necessary.The present 30 t/h production circuit recovers from 5 to 50% of the silver in the ore at a concentration ratio between 25 and 250. The circuit also contributes to a better understanding of ore mineralogy, as an 'on-line' indicator of elemental silver content."

Jan 1, 1985

Jan 1, 1985

By R. K. Singhal

A variety of mining equipment is used in the mining of oil sands by surface mining. This includes bucket wheel excavators, draglines, hydraulic shovels and off-highway trucks. This paper examines the existing mining schemes and equipment used Peculiarities of oil sands surface mining and their influence on equipment selection, utilization and mining schemes are described. Recent developments undertaken to improve mine productivity are also dealt with together with some notes on proposed measures to obtain further gains in productivity.

Jan 1, 1985

By R. F. Droullard

The Bureau of Mines has used gross alpha and gross beta detectors to continuously measure radiation working levels for a number of years. During this time, improvements have been made in the design and performance of continuous working-level (CWL) detectors. This report discusses the improved designs and some of the operating principles and applications of CWL detectors in the measurement of radon daughter products in mines and dwellings.

Jan 1, 1985