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By J. Mackintosh Bell

External trade strongly influences the well being of all nations. In the modern economic mechanism, no country is so well endowed that it has not to import commodities from others and to export its products in turn to make good its deficiencies, to rectify or improve its financial structure. From the standpoint of international commerce, Canada is strategically well placed. On the south she is bounded by the richest country in the world. On the east she faces the Atlantic, on the west the Pacific. On both coasts there are fine harbours to which lead great lines of railway that span the continent. Canada is now fifth among the exporting nations of the world. For disposal abroad, she has enormous quantities of primary commodities and substantial amounts of manufactured goods as well. But she is far from being self-sustaining. She is unusually dependent on foreign trade, not only because of the commodities she has to sell but because of the lack of many essential articles she does not or cannot produce. To Canada, external commerce is vastly more important than internal trade. The wealth of nations is decided by their ability to produce more than they need, to sell more than they buy, and to build up favourable balances resulting from trade or services. With few countries, however, are returns perennially satisfactory. Fruitful periods are followed by leaner years. In times of prosperity foreign credits are increased, monetary systems strengthened, reserves accumulated to withstand recurring days of strain. Today, the foundations of financial systems are being re-examined, "dogmas hitherto accepted as canonical are being questioned" . It is not only in Europe and America that men search for illumination in problems arising from monetary restrictions.

Jan 1, 1933

This report provides the results of an industrial engineering study that assessed the safety and efficiency of underground ore handling in U.S. metal mines. One of the primary findings of the study was the improvement needed in controlling muck size in the ore handling stream. Oversize ore causes much additional labor, creating work stoppages and is a principal cause of accidents in metal mines. This report includes data on block caving, back cut and fill room and pillar, shrinkage stoping, and sublevel stoping.

Jan 1, 1974

By S. J. Ristorcelli

Historically, geologic data has not been adequately considered in resource estimation. More recently, with the use of computers and sophisticated estimation algorithms and geostatistical justifications, geology has been downplayed further. Many reasons are given for not using geology including cost, time and irrelevance. None are valid. Boundaries defining mineral domains should be used in computer-generated resource estimates. Selected case histories show how the failure to honor geology has caused discrepancies in resource estimates of actual in-place resources. After-the-fact differences have included decreases in tonnage of up to 50% and increases up to 300%; partial to complete recategorization of material; and 50% decreases in grade. The costs of gathering and using geology are trivial compared to the potential consequences.

Jan 1, 1994

By Stanislaw Trenczek

Natural hazards such as rock bumps, methane, coal dust explosions, airborne respirable dust, outbursts of gas and rocks, water, radiation caused by natural radioactive materials, spontaneous fires, and climatic hazards, occurring in the Polish hard coal mines, should be controlled. These hazards are characterized by different scale levels numbered from 2?5. To recognize the amount and levels of hazards, research works were carried out in 109 mining districts of mines belonging to Jastrzebska Spólka Weglowa, Katowicki Holding Weglowy and Kompania Weglowa. These are 86 % of all mines and could be regarded as representative of the majority of Polish mining. The hazards have been classified as regards the frequency of their occurrence as: commonly occurring ? with a frequency of 100 % (like airborne respirable dust and fire hazards), high occurrence frequency ? frequency from 60 to below 100 % (methane hazard ? 83.5 %, coal dust explosion hazard ? 92.0 %, and water hazard ? 99.1 %), medium occurrence frequency ? from 30 to below 60 % (rock-bump hazard ? 52.3 % and climatic hazards ? 51.4 %), and episodic occurrence frequency ? below 30 % (outburst of gas and rocks and radioactive hazards). The dynamics of effects of growth in hazard levels to their intolerable values is diverse. Some of them are passive in nature, which allows for longer observation of changes and appropriate early response (as for climatic and spontaneous fire hazards). However the majority of them take on the character of disasters, like methane or coal dust explosions and damage of the excavation structure ? as occurs after a rock-bump or rock outburst; and creation of an atmosphere unfit for breathing ? during open or spontaneous fires, or after gas outbursts containing methane. There are also latent hazards whose effects do not influence indeed a process of production; however they are detrimental to health when a worker is exposed for a long time to airborne respirable dust and radiation. For other types of hazards a level of danger may be only estimated. Since the systems monitoring allows a wider range of control, therefore, aside from rock-bump and methane hazards, there are monitored also fire hazards including measurements of other air parameters (velocity, pressure, humidity, temperature, O2, CO2 concentration). A few types of monitoring systems are used in Polish mines, like the monitoring systems for environmental parameters such as SMP-NT, SMP-NT/A, the telemetric systems CST-40, CST/A, including the computer-aided system for methanometry control officer SWµP, the computer-aided measuring systems KSP-1, KSP-2, KSP-2C, or the production and safety control system VENTURON. The underground part of the systems monitoring of natural hazards contains measuring devices and equipment for automatic control (power-off) of machines and electric devices in case of increased methane hazard. The surface part of the monitoring system allows the measuring data to be visualized and pre-alarm (warning) and alarm states to be displayed. Furthermore it makes it possible to archive and report the data and to control the underground supply and signalling devices. The EMAG Institute developed monitoring methods to extend a measuring range of monitored parameters (such as methane and fire hazards) as well as to monitor so far unmonitored hazards like dust hazards (by continuous monitoring of dust levels in mine air) and climatic hazards (by online monitoring climatic parameters of mine air).

Aug 1, 2013

By L. A. Ayres da Silva, J. P. G. Negri, A. L. M. Ayres da Silva

"Rock hardness is dependent on the type and quantity of the various mineral constituents of the rock and the bond strength that exists between the mineral grains. As the book “The Complete ISRM Suggested Methods For Rock Characterization, Testing and Monitoring:1974-2006” explains, hardness is a concept of material property. As such, the quantitative measure of hardness depends on the type of the test employed.Among the three types of tests that have been used to measure the hardness of rocks and minerals: 1) indentation tests; 2) dynamic and rebound tests; 3) scratch tests, the authors of this paper chose indentation tests, more specifically the Vickers test, and complementary verified the correlation between the results of the Schmidt sclerometer tests (rebound tests) and the Vickers microhardness tests in a set of the same 9 (nine) granite rocks.The objective of this research was to verif y the correlation of one created index, based on the Vickers test that can be able to represent the rock material hardness. We know that Vickers tests determine the microhardness of individual rock minerals. A pyramidal shaped diamond is applied to the surface with a specified force. The area of the permanent residual deformation divided by the applied force is a measure of the hardness. Using the relative participation of the mineral components of the rock, we established a hardness index denominated EVM (Equivalent Vickers Microhardness).The correlation of the EVM with others strength properties and application parameters like UCS (Uniaxial Compressive Strength) to study sawability of granite blocks have presented very good results. The association of equivalent microhardness with others strength parameters, allowed to find powerful algorithms for analyzes of the rock materials behavior under diversified circumstances, as the sawability of granite blocks, as we can see in Fig. 1.Other very interesting correlations were found as the EVM values and that were obtained by the use of the Schmidt impact hammer for the superficial hardness determination."

Jan 1, 2015

By F. Essrich

A quantitative rockburst hazard assessment procedure was introduced on Elandsrand Gold Mine at the end of 1994. It is currently used to evaluate the seismicity-related risk in production areas on the mine. Six parameters related to seismicity, geology, mining layout, and production are rated and results are used as a planning tool on a regular basis. The applied assessment can be considered successful in that it promotes awareness of the seismic hazard and provides an opportunity to address seismicity-related mining problems. A comparison between high risk panels and those working areas with rockburst incidents showed that high hazard ratings reliably forecast the occurrence of larger events in the following month but they do not necessarily predict those working places with rockburst-related accidents. From this one may conclude that high levels of seismicity do not coincide with high rockburst rates.

Jan 1, 1997

By K. Mallikarjuna Rao

There are several methods available to estimate deflection and ultimate Capacity of laterally loaded piles. In this investigation an attempt has been made to verify the existing methods for prediction of ultimate lateral resistance and deflection with the laboratory and field test results reported in the literature. A 75 pile loading test data obtained from the literature was used to evaluate two methods designed to predict the ultimate lateral resistance of rigid piles and three methods designed to predict the lateral deflections of rigid piles and four methods designed to predict the lateral deflection of flexible piles subjected to lateral loads. The accuracy and precision of each method is quantified statistically. The statistical results of the overall analysis indicate that the mean values of the ratios of predicted to measured lateral capacities vary from 0.62 to 1.14 with an average of 0.88. However, the settlement predictions were much more widely scattered than the ultimate load predictions and in general all the methods have a tendency to under predict the deflections. A new method is proposed by modifying the Broms's method to estimate the lateral deflections of free headed rigid and flexible piles separately. The proposed modified methods were found to be reasonably good in comparison to existing methods and to overestimate deflections.

Jan 1, 1996

By C. E. Coleman, Joseph D. Davis

During some distillation experiments conducted by the Bureau of Mines in cooperation with the Trent Process Corporation it was observed that amalgams of heavy petroleum oils and finely pulverized coal tended to produce a denser coke than that obtainable from the coal when retorted alone . Even anthracite coal when retorted with oil yielded a coke . This led the writers to believe that by mixing a lowrank coal ( sub-bituminous or even lignite ) - with asphaltic oil and retorting it, a coke suitable for domestic fuel could be made . Thus there was contemplated the production of domestic coke and the utilization of a low- grade oil in one operation . - In order to decide on the practicability of this process , it was necessary to know the value of products obtainable by such a method , as compared with those obtained by separate distillation . A laboratory method was therefore devised , and while it was realized that no small - scale testing apparatus for destructive distillation gives results that are directly applicable to commercial - scale operations , by keeping distillation conditions uniform for comparative tests , results were obtained valuable for purposes of comparison . The plan was to distill mixtures of coal and oil in a laboratory retort , and then distill the constituents separately under the same conditions . The comparative quantities of products yielded were thus directly obtained , and their quality was determined by analysis . The following are the main points investigated : ( 1 ) Quantity and quality of coke ; ( 2 ) Quantity of oils boiling below 221 °C . ( gasoline stock) and oils boiling at 221 to 300° C . ( kerosene stock) ; and ( 3) Quantity and quality of gases .

Jan 1, 1922

By Neall. George M.

No method of roof control yet devised has proven to be universally acceptable for the wide range of strata conditions experienced in U.S. coal mines. However, a relatively new innovation, the roof truss, has proven itself capable of preventing roof failures which both conventional and resin bolting could not. Presently, the economics of roof trusses are not favorable when compared to bolting due primarily to drilling and installation procedures, but this is expected to change with improved truss and equipment designs. To realize the full potential of this new method of roof control, design criteria are needed which can optimize the effect of the truss for varying strata conditions. A review of the literature reveals that some work has been conducted on the roof truss. 1 Gambrell and Haynes (1970) showed that the roof truss is superior to angled roofbolts installed through a header. Sheorey, Verma, and singh2 (1973) used statics to prove that the optimum angle of inclination should be greater than 450? However, to date, no systematic attempt has been made to establish design criteria. In this report, the problem was approached in three ways. First, model studies were performed to determine general trends of truss support as a function of a number of variables. This provided a better understanding of the support mechanism involved. Secondly, beam theory was employed to calculate the actual support capacity of a truss, realizing the many simplifications, assumptions, and shortcomings of this approach to such a complicated problem. Last, field testing will be utilized to test the hypotheses previously developed and provide hard data to further synthesize roof truss design criteria. Field testing has recently commenced and should be complete before mid 1977.

Jan 1, 1977

By J. Grubb

"The undertakings described in the paper titled “Study on correlation of quantified coal rank with self-heating temperature” by Wang and Luo in the November 2015 issue of Mining Engineering (Wang and Luo, 2015) are mathematically sustainable and an acceptable extension of work performed by Smith and Lazzara (1987) for the U.S. Bureau of Mines. The paper is not an accurate explanation of the currently accepted leading practice for determining the propensity of a coal seam for spontaneous combustion. The paper could lead a practitioner to an oversimplified conclusion on how to determine the propensity of a coal seam to spontaneously combust.The spontaneous combustion of coal is a complex and not fully understood reaction. What is understood is that many more factors other than selfheating temperature (SHT) and coal rank are required to sufficiently evaluate the risk of spontaneous combustion in a particular coal seam. A superficial assessment can lead to an improper response to the risk. Some statements on the next steps through an appropriate literature search would have made the authors’ conclusions more credible.The SponCom 2.0 software, updated by the National Institute for Occupational Health and Safety (NIOSH) in 2011, provides a path for evaluating the susceptibility of a coal seam to spontaneous combustion. In addition to proximate and ultimate analyses to establish coal rank, and therefore an estimate of SHT, the program includes the history of heatings, friability, seam thickness, overburden thickness, rider seam presence, pyrite presence, face and butt cleat densities, geothermal source presence and other geological features in the assessment. Mining conditions including floor heave, rib sloughage and rate of advance are also assessed to conclude a propensity for spontaneous combustion."

Jun 1, 2016

By A. Frank Alsobrook

DOUG HALBE: Thanks, Terry. And in spite of your introductory comments, I'm going to attempt to continue our hallowed tradition of saying nice things about the speakers. This is really a serious comment now. We, as mineral processing and mill people, don't often talk to people outside our general operating area. One thing that we've tried to do in this operators' symposium is get speakers from various types of plant operations to help illustrate all the things we have in common. Our next speaker is from the industrial minerals area. I think there's a lot to be learned from industrial minerals operations. Some of the people in the last session learned some things about fine grinding in industrial mineral operations. I was a little surprised to see people there grind to 2 microns. Our next speaker is Frank Alsobrook. Frank is another nonmetallurgical engineer. He has a degree in geology, a master's of science from the University of Wisconsin. He's had his own very successful consulting company for a number of years. This is your 11th anniversary, Frank? Very good. He's also the immediate past chair of the industrial minerals division. I think the folks at the speakers' table should be ashamed. You have been so rowdy that Frank chose to sit in the audience. [laughter] We'd like you to come up now, Frank, and tell us some things that you've seen that might be useful to us. INTRODUCTION FRANK ALSOBROOK: The three topics addressed briefly are (1) teamwork and operations modeling, (2) the pitfalls of capital conservatism, and (3) the potential for by-product recovery. Ideas for improvements in these areas are not unique to industrial minerals but apply to metal mining and processing operations, as well. Several additional topics are suggested at the end of the paper.

Jan 1, 1998

By Harry A. Lipsitt, Rollins E. Hook, Attwell M. Adair

A necessary condition for a uniaxial stress distribution in compression testing is that the specimen end surfaces make full contact with the apparatus compression plates. In addition all compression surfaces must be machined perpendicularly to the loading axis. In general this condition is not sufficiently fulfilled in a simple apparatus. Therefore on application of the load the compression plate may first touch the specimen at one point only. This may cause crumbling of the specimen if the material under investigation is brittle (e.g., ionic crystals). It also precludes a precise study of the beginning of deformation as the effective cross sectional area is unknown. In addition a complex stress state is set up which renders quantitative work impossible, e.g., on dislocation density and arrangement as a function of stress. To overcome these difficulties a "self-adjusting" upper compression plate is required. A simple and reliable method of achieving this is shown in Fig. 1: A steel hemisphere is placed on the specimen. As soon as the compression plate (which no longer needs precise machining) makes contact with this hemisphere the load is uniformly distributed over the whole specimen surface, and a homogeneous uniaxial state of stress results. An advantage of the method is that the loading is always central, even when the specimen surface is not parallel to the compression plate (Fig. 1, dashed line). Therefore to a first approximation a uniaxial state of stress is maintained if the misorientation of the specimen end surface is small. Two typical stress strain curves of identically prepared sodium chloride crystals are shown in Fig. 2; curve 1 was taken without and curve II with the hemisphere under otherwise identical conditions. The improvement in the accuracy of defining the beginning of elastic and plastic deformation is clearly indicated. The writer wishes to thank the Deutsche Forschungsgemeinschaft for financial support, and Professor P. Haasen for providing facilities for this work.

Jan 1, 1962

By Hrayr Agnerian

The fair market value of an exploration property is determined by its potential to host a mineral deposit. This potential is gauged by the results of previous exploration, exploration stage, meaningful past expenditures and remaining targets that are not yet tested. Values of exploration properties can be viewed as distinct points in a three-dimensional space defined by orthogonal axes, namely: Exploration Stage (x-axis); Cumulative Expenditures (y-axis); and Property Value (z-axis). In general, these values are estimated by applying activity factors on previous exploration expenditures, e.g. an activity factor of 100% for an active property with good potential and a factor of 50% for an active property but past expenditures have not upgraded the property. At certain periods, a market factor may also be applied to reflect the activity of mineral property acquisitions. For properties that do not exhibit any exploration potential, only nominal values are applied.

Jan 1, 1996

By T. R. Kostecki, A. J. S. Spearing, A. Hyett, M. Gadde

Ground control research for underground coal mining has progressed significantly over the past several decades. With this progression, and the ability to analyze and model underground conditions, underground working conditions have significantly improved. In order to progress further, the behavior of roof support must be known and be adequately modeled, such that models can be used for support design under different geological and mining conditions. This paper discusses the results from a research project funded by the U.S. National Institute for Occupational Safety and Health (NIOSH) and undertaken by Southern Illinois University Carbondale and Peabody Energy. The research involved installation of active and passive instrumented bolts in mines, recording relevant in situ data and then attempting to model the behavior of the bolts as mining progressed. Such calibrated models could aid in design of roof supports under different geological and mining layouts and thus, hopefully, further improve rock related safety.

Jan 1, 2012

By F. E. Rizzo, L. R. Bidwell, D. F. Frank

THE poor high-temperature oxidation resistance of the refractory metals becomes an important problem as higher operating temperatures are sought. A meaningful analysis of their oxidation behavior requires a knowledge of the phases that can appear during oxidation as well as their relative stability. Although several extensive investigations have been carried out to obtain this information for the W-0 system,1-10 serious inconsistencies still remain. First, the standard free energies of formation (AG°) determined in recent studies which used the solid electrolyte galvanic cell technique6,7,9 differ significantly from those obtained primarily from gas equilibration measurements.1,3,4,10 The disagreement is especially large for the highest oxides. These data have been used to predict the decomposition temperatures of WO2. 72 and WO2.90.1 A considerable extrapolation is required, resulting in a large uncertainty in the decomposition temperatures. Second, Bousquet and perachon3 have presented convincing evidence, ob- tained by gas equilibration measurements, in support of the long-contested existence of W30. Phillips and chang,ll on the other hand, were not able to observe this phase under similar experimental conditions. The purposes of this work, which is part of a continuing investigation of the W-Mo system, were to resolve the discrepancies between the AGO measured by gas equilibration and solid electrolyte galvanic cell techniques, to extend the latter measurements to lower temperatures, to redetermine the WO2.72 and WO2.90 decomposition temperatures, and to apply the more sensitive electromotive-force method to the question of the existence of W3O. I) EXPERIMENTAL PROCEDURE The measurement of ?G° of reaction by the use of calcia-stabilized zirconia solid electrolyte galvanic cells has been described previously.12 The method is based on the measurement of the difference in chemical potential of oxygen between an electrode containing the two oxides of interest and a reference electrode of known oxygen activity. Two different types of cell holders were used in this study. The first type of apparatus has been described earlier." It consisted of two solid electrodes separated by a disc of electrolyte. Both electrodes were exposed to the same stream of purified helium. With this design a gaseous transport of oxygen between the two electrodes is possible. The second type of apparatus, which has also been described earlier,14 effectively separated the two electrode atmospheres. It utilized a closed-end impervious, calcia-stabilized zirconia tube that was open to the atmosphere. The tube served as an electrolyte for the cell and provided a means for separating the anode compartment, which was held under a static vacuum, from an air reference cathode. The cells and reactions of interest are described in Table I. High-purity tungsten metal was obtained from the Fansteel Metallurgical Corp. and the Allied Chemical Corp. Table II contains an analysis of each material. WO3 was prepared by oxidizing the metal in air at approximately 600°C in high-purity recrystallized alumina boats and by the dehydration of reagent-grade tungstic acid in alundum boats. The two methods of preparing WO3 resulted in slightly different purities.

Jan 1, 1968

"The Midvale. Plant of the United States Smelting, Refining and Mining Company, situated twelve miles south of Salt Lake City, consists of mills for concentrating lead-zinc ores and a custom lead smelter.The milling department includes a 475-ton gravity mill for ores from the United States Mines at Bingham, a 100-ton Huff electrostatic zinc plant and a 60-ton pilot flotation mill for differential separation of lead and zinc. The gravity mill and electro¬static plant are being replaced by a 600-ton differential flotation plant, now under con¬struction, for differential separation of lead, zinc and iron. This new mill will have cap¬acity for treating custom ores in addition to ores from the company's mines at Bingham.The smelting department is equipped to handle 1600 tons of charge per day through six blast furnaces, 48 inches by 160 inches at the tuyeres. All gases from both blast furnaces and roasters are filtered through baghouses, which remove the dust from the gases so effectively that even when the plant is running at full capacity no smoke can be seen coming out of the 450-foot brick stack handling rca2ter gases, nor out of the two shorter steel stacks which take the blast furnace gases. On this account the Midvale plant has come to be known as the ""smokeless smelter.""The blast furnace gases are filtered through 832 woolen bags, 33 feet 6 inches by 18 inches in diameter, and 1200 woolen bags, 28 feet by 12 inches in diameter."

Jan 1, 1925

By Zhang Junzhi

This paper relates cross-border mergers and acquisitions (M&A) risk management theory to actual coal enterprises in China. The 3 phases of M&A are preparation, implementation and integration. By using the Analytic Hierarchy Process and fuzzy evaluation methods, we will try to establish a model to assess risks of the cross-border M&A of China?s coal enterprises. We then apply this model to the case of Yankuang Group acquisition of the Felix Company and receive the assessment results. There are significant reasons for quantitative research on risks of cross-border M&A of China?s coal enterprises, such as effective prevention and risk-aversion, and facilitation of cross-border M&As.

Aug 1, 2013

By Tim Robinson, Michael S. Moats, Masatsugu Moritmitsu, Kathryn C. Sole, Lauri Palmu, Frank K. Crundwell

"Process technology and design trends for copper, zinc, and nickel electrowinning cellhouses include focusing on energy reduction, productivity, and acid mist abatement. Larger electrodes, longer cells, automation, and higher current densities are leading to more capital-effective designs. The latest cellhouse designs include installation of automated electrode-handling systems, thereby removing more operators from the cellhouse. These technology and design trends result in lower electrowinning operating costs and improved purity of electro won cathode.INTRODUCTIONTechnology transfer between similar industries is an important process in improving product quality and productivity, and reducing operating costs. The electrowinning (EW) recovery of base metals, such as zinc, copper and nickel, is no different. The zinc industry with its larger EW product-handling requirements as compared to nickel and copper, has been driven to automation technology and the use of larger equipment. This technology has been transferred to copper. Nickel has led development and application in large-scale anode and divided-cell technologies but, due to nickel being produced in multiple forms (not just cathode) and being a small part of the whole complex nickel process route, the quantities of electrowon nickel are small compared to copper and zinc. Copper process technology in acid mist abatement was recently transferred to nickel. The focus in copper EW has been on energy reduction and productivity."

Jan 1, 2012

By M. Alvarez-Silva, A. Uribe-Salas, J. A. Finch, M. Mimezami

The point of zero charge (PZC) of electrokinetically anisotropic minerals (chlorite and serpentine) was determined using the Mular-Roberts (M-R) titration technique, and compared to isoelectric point (IEP) obtained from electrophoretic mobility measurements. To validate the M-R technique, the point of zero charge and isoelectric point of two isotropic minerals (alumina and silica) were shown to be comparable. For serpentine and chlorite, respectively the PZC was found at pH 4.3 and 4.6, while the IEP occurred at pH 3.2 and <3. Settling tests showed that the maximum settling rate, which corresponds to aggregated particles, for chlorite was around pH 3, i.e., close to the IEP; lizardite did not show a conclusive maximum.

Jan 1, 2009

By J. B. Oosthuizen

Mechanical rock breakers are used in block caving operations to reduce the size of ore fragments which are too large to pass through grizzlys at the load-haul-dumper tipping points. Several layouts of grizzly, rock breaker and ore pass are possible. The authors evaluated three different layouts at the Premier Mine Division of De Beers Consolidated Mines. The first layout consisted of a 15m surge bin before the breaker, which was located 15 m below the production level. The second layout had a 43 m longs urge bin, with the breaker located 43 m below the production level. The third layout did not have a surge bin, the breaker was located on the production level and operated at the tip. The ore throughput, availability and utilisation, delays, costs and operational experience with each system are discussed. It was found that the rock breakers did not represent a bottleneck in the ore transfer system and a surge bin did not significantly improve the production capacity. The mine has decided to make use of rock breakers situated on the production level, breaking rocks at the tip.

Jan 1, 1997