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By C. Chapman, P. Cowx

"INTRODUCTIONTetronics Research and Development Co. Limited has installed several plasma torches for steel heating in continuous caster tundishes. An extensive demonstration program on a 14 tonne tundish reported the following advantages of plasma heating.• close control of steel temperature to ± 5°C;• a reduction of the furnace tapping temperature of up to 20ºC, leading to savings in energy and refractories costs ;• improvement in steel quality, to produce a slab product with an equi-axed crystal structure and a reduced number of large sub-surface slag inclusions;• the virtual elimination of oxygen pickup in the tundish; and• the capability of making ferroalloy trim additions to the tundish to permit a change of steel grade during casting, greatly decreasing inventory costs.The Need for Tundish HeatingIn the continuous casting of steel, the function of the tundish is to transfer the molten metal between the ladle to one or more continuously fed casting moulds. Figure I shows a typical temperature profile of molten steel in the tundish over the first cast cycle. It is observed that a rapid drop in temperature occurs both at the start of the cast, due to the tundish refractories absorbing heat, and also during ladle changeover. In addition, as a result of thermal losses through the ladle sidewalls, there is a gradual decline in the bulk steel temperature over the entire heat cycle. Consequently, in normal tundish operation, it is necessary to cast with a high superheat (25°C to 30°C + above steel liquidus temperature) in order to prevent freeze-up of the strand. Problems of high temperature variation and the potential of the steel solidifying in the tundish are greater for small caster units of low thermal mass . A high steel superheat increases the steelmaking vessel process time and refractory wear and prevents the formation of a uniform equi-axed solidification structure in the cast steel, resulting in centre line segregation and porosity. The large drop in the casting temperature that occurs during unsteady state operation causes an increase in the number of sub-surface inclusions, reducing the value of the product. Accordingly, plasma heating may be employed to maintain the molten steel at an optimum temperature to produce a slab of consistent quality."

Jan 1, 1989

"Sink-float analysis is often used to obtain yield-ash and density partition curves in the coal industry. These provide a valuable tool for evaluating the performance of a separation process. However, for dense minerals, obtaining complete grade-recovery and density partition curves is more difficult due to the lack of heavy liquids available with the required densities. This paper examines a potential solution to this problem which is to perform batch fractionation of mineral samples in a laboratory-scale REFLUX™ Classifier using high viscosity fluidising liquids. The REFLUX™ Classifier is a gravity separation unit consisting of a system of parallel inclined channels positioned above a vertical fluidised bed. Operated in semi-batch mode, a charge of particles is fluidised from below and particles up to a certain density are elutriated from the top of the system. The fluidisation rate is then increased incrementally to fractionate the sample at progressively increasing densities. Previous work by Hunter et al. (2014) and Iveson et al. (2015) has shown that this method provides excellent agreement with yield-ash and partition curves for coal, especially when glycerol solutions are used as the fluidising liquid. This approach has now been extended to obtain the grade-recovery and density partition curves of high density mineral samples. This method has the potential to provide the minerals industry with an effective tool to evaluate the performance of unit operations separating at cut points higher than the available heavy liquids.INTRODUCTIONMeasuring efficiency and effectiveness is of key importance in the continuous improvement of mineral processing plants. For density based separation, one way the performance of a process can be evaluated is the measurement of density-based partition curves. Currently, this is done in the coal industry using the sink-float method, where heavy liquids are used to fractionate particles into discrete density intervals. However, with high density minerals such as iron ore, liquids of sufficient density are rare, and in most cases also pose serious health and safety concerns to laboratory operators. Most commercial laboratories do not perform sink-float separations above a density of about 4400 kg/m3, the maximum density of Clerici solution without operating at excessive temperatures (Koroznikova, Klutke, McKnight & Hall, 2007; Rosenblum, 1974)."

Jan 1, 2016

By O'Halloran. Gerard F.

"ECSTALL MINING has installed in their plants the most modern equipment in the mining industry. At the minesite, digital blocked frequency controls are used to monitor all crushers, conveyors, ventilation equipment and pumps from underground. Distant pumping stations are monitored and controlled by radio. Modern friction skip and cage hoisting systems have been installed with static power supply designed for automatic operation. Rotary-type compressors of recent design are in service in place of the conventional reciprocating-type units. At the concentrator, the 800- and 1500-hp synchronous motors driving the grinding mills have static field excitation and pneumatic clutches, still meeting modern-day concepts, having been• installed in 1966. The maintenance work load has increased annually for the past eight years. The modern plant, with all the present-day sophistication, must have a welltrained and well-organized force of skilled workers, and a maintenance system which will supply realistic facts and guidelines. This presentation will review the relative location of plants, utilities, maintenance and services, plant maintenance control and mechanical control. It is the hope that enough information will be presented to weigh the size of the job and how the resources are utilized for controlled maintenance."

Jan 1, 1974

By Claudio Rocha Rosales

"Peñoles is a mining group with integrated operations for the smelting and refining of non-ferrous metals, and it is also a chemicals producer. Peñoles is the world’s foremost producer of refined silver, metallic bismuth and sodium sulphate. It is also the leading Latin American producer of refined gold, lead and zinc. The Met-Mex Peñoles Zinc Plant commenced operations in 1973 with an annual production capacity of 105,000 t/y zinc. Since then, production capacity has increased, and at present, it stands at 240,000 t/y zinc. In this paper, the leaching process and particularly the operation of the jarosite circuit is reviewed, specifying process improvements to treat high iron calcines.INTRODUCTIONTwenty years ago the Electrolytic Zinc Plant in Peñoles was treating high quality zinc concentrates with low concentrations of iron (~7.5 wt.%) and silica (1.8 wt.%). Nowadays the quality of zinc concentrates is poor with a typical iron content of around 11 wt.% and silica at 2.0 wt.%. This has created numerous processing problems in our roast-leach-purification- electrolysis sections. In order to meet customer requirements it is necessary to find processing solutions to assure the operational continuity of the plant. These processing solutions are the focal point of this paper.REVIEW OF THE LEACHING PROCESSThe purpose of the leaching process is to recover the metals, mainly zinc, through a series of extraction stages with sulphuric acid solutions, which progressively increases the zinc dissolution. After the series of acidification stages, the solution, which is rich in iron, is sent to the jarosite circuit to separate zinc from iron (Garcia & Valdez, 1996). The first step of the leaching process is the neutral leach circuit which produces a zinc sulphate solution that is sent to the purification section for the removal of impurities such as cadmium, cobalt and copper. Then this solution is sent to the tank house to feed the electrolytic cells."

Jan 1, 2016

By G. R. Baiden

"An Automatic Haulage Truck (AHT) has been developed for manless tramming of run-of-mine material in an operating mine. The AHT has a 70-ton capacity and uses an electric trolley system in combination with a computer control system to operate the vehicle. The purpose of the AHT was to provide a high capacity, high productivity material transfer system where conveyor belt applications are not immediately practical.The AHT project was started in 1983 at Inco Limited, Ontario Division as a result of the need for rapid material transport to match increased extraction rates resulting from bulk mining methods. The original concept was to use a continuous loader with the truck. However, in order to minimize development problems the truck project was considered a stand-alone project.The AHT project consisted of concept development, preliminaryand detailed design, manufacture, surf ace testing and mine implementation.The AHT was manufactured and ready for testing in 1988. At this point the truck was first moved onto the test track for debugging. This proved successful and in 1989the decision was made to install the AHT at Little Stobie mine on 2000 level. Commissioning of the system was started in 1990and at present a fully functional automated haulage system is in place at Little Stobie mine producing 3000 tons/day.This paper describes the project presenting results achieved to date."

Jan 1, 1992

By A. Manohar Rao

Underground mining in general and more so the coal mining is a hazardous venture as it is a struggle against nature and natural forces. The stability of roadways has a direct impact on production and productivity. The roadway stability can be strongly influenced by the direction of the drivage. The stress studies are useful to provide a frame work for understanding the influence of drivage direction on roadway conditions, and to illustrate how mapping techniques can enhance this understanding. The act of mining can concentrate and re-orient the original stresses. Whenever coal is removed, the overburden weight that it carried is transferred. Vertical stresses are similarly affected when the roof is deformed or failed. The Singareni Collieries Company Ltd., a joint Public sector undertaking of the Government of Andhra Pradesh and India is conducting coalmining operations in the Godavari Valley Coalfield and is catering to the needs of a large part of South India. With the technology update, it is looking for safe mining and to achieve higher production. As a part of this, an attempt is made to understand the stress conditions prevailing on the mine blocks by different ways and means in terms of geology, structure and tectonics of the Godavari Valley coalfield, satellite imagery studies, cleat pattern, stress measurement studies conducted in different mine blocks, and stress mapping technique.

Aug 1, 2013

By J. G. Peacey

"Canada has a special place in non-ferrous pyrometallurgy because it is the only country in the western world that is a significant producer of all the major non-ferrous metals; aluminum, copper, lead, magnesium, nickel and zinc. This large non-ferrous pyrometallurgy industry has developed because of Canada's abundant mineral wealth and energy resources. Table I summarizes the number of primary non-ferrous production facilities in Canada and their share of western world production.Production of non-ferrous metals is a mature, capital intensive business and its basic processes have been in use for many years. Nevertheless, these processes have continued to evolve in response to changing needs and external pressures; such as the energy crisis of the early seventies; historically low metal prices in the early eighties and the continuing pressure to reduce plant emissions and improve in-plant working conditions. Canada's major metallurgical companies: Alcan, Cominco, Falconbridge, Inco and Noranda have played a leading role in pioneering new process technology and continue to meet the difficult challenge of keeping their operations competitive in the global metals market. This paper will try to give an overview of the major developments in non-ferrous pyrometallurgy, largely from the Noranda and Canadian perspectives, highlighting the current status of process technology and possible future directions.AluminumCanada has the world's second largest aluminum smelting industry and its capacity has expanded rapidly in recent years with the completion of several large projects in Quebec. The location and capacity of the Canadian aluminum smelters are given in Table 2. All these plants use the Hall-Heroult process, that was invented over a century ago but over the last twenty years considerable improvements have been made to increase productivity, reduce power requirements and emissions.The developments in aluminum cell technology can be illustrated by the experience at Noranda Aluminum. In 1971, Noranda Aluminum started its first pot line using Kaiser's P69 prebake cell, which was considered, at that time, the best available technology. The P69 cell was designed primarily for high productivity, operating at 150 000 amps and high current density to produce just over tonne Al per cell-day. The P69 cell is a simple design, typically operating at about 88070 current efficiency and 15 800 kWh/tonne Al. When Noranda Aluminum decided to expand in 1980, the Alcoa 697 cell was selected as it then represented the most proven, stateof- the-art technology. This cell is similar to that installed at Alcan's new Grande Baie and Laterriere smelters and is designed to operate at 180000 amps and 93070 current efficiency, producing about 25070 more aluminum per pot-day than the P69 cell using about 15070 less power. The 697 cell has a much more sophisticated cell design, with very good balancing of the magnetic field giving a flat metal pad and allowing efficient operation at the higher amperage. Alumina is fed via point feeders that provide an almost continuous feed allowing close control of the alumina level in the bath and the use of low-ratio bath composition, giving much higher current efficiencies."

Jan 1, 1991

By D. Sharma, A. K. Singh, R. Singh, P. K. Mandal, M. Sarkar

"This paper deals with the stability investigations carried out at the XIVth seam of Jitpur colliery. The study was conducted to investigate the possible causes of roof cavity formation and face spalling at the middle slice face of block-3 longwall panel and to suggest remedial measures. The instrumentation and monitoring work was carried out in the panel over a period of nine months. On the basis of observations, it was found that if the maximum face span was reduced from the existing 4.8 m to 3.6 m, and if the face time schedule cycle was reduced from a maximum of 37 days to about 18 days, this problem could be eliminated. The recommendations of CMRI have been implemented in the middle slice face of block-4 panel with success. IntroductionModerate to steeply dipping, undisturbed seams of uniform thickness are worked by way of inclined slicing parallel to walls. In this method, the seams are treated as a combination of several moderately thick seams dipping parallel to roof and floor. Numerous variations of multislice mining have been used worldwide to get high coal recovery under local conditions of geology, subsidence control, proness to spontaneous combustion, statutes and economics. Multislice mining can proceed either downward descending from the roof or upward ascending from the floor. Ascending methods require backfill behind the working face to provide a base for the next slice. It is also adopted for surface protection against subsidence or mining under a massive roof. This paper presents a scientific study conducted in Jitpur colliery, IISCO where a 9 m thick seam is mined in three slices in ascending order with stowing."

Jan 1, 2002

By Douglas W. Reeve, Hoc Nghia Tran, David Barham

"In kraft pulp mills, the spent pulping liquor is concentrated and used as fuel in the recovery boiler. Extensive deposits are formed in the upper section of the boiler due to the very high ash content of the fuel and the volatite nature of the ash. Deposits are composed of Na2S04, Na2C03 NaCI, some potassium salts and reduced sulphur compounds. Chloride and potassium salts are enriched in the deposits compared to the smelt due to their greater volatility.Severe corrosion of the superheater tubes in a recovery boiler has been traced to three factors: a non-uniform temperature profile in the flue gas, relatively high operating steam temperatures and high chIoride and potassium concentrations in the fireside deposits.The role of chIoride and potassium in superheater corrosion has been explained by increased Iiquid phase in deposits. Together with corrosion studies, this information has shown that kraft recovery boiler superheater corrosion due to the chloride and potassium enriched deposits can be avoided by proper boiler operation and by judicious superheater and furnace design.IntroductionThis investigation of recovery boiler superheater corrosion was initiated by the discovery of severe corrosion of the final stage superheater in a Canadian closed cycle kraft pulp mill(1,2). Metal wastage leading to tube failure was believed to be due to three major causes : the relatively high operating steam temperatures, the uneven distribution of flue gas temperature across the boiler which created a "" hot spot"" and the high chloride and potassium concentrations in the superheater fire side deposit. The mill responded to the problem by i) lowering the superheater steam temperature from 475°C to 380°C, ii) minimizing the chloride content in the spent pulping liquor, by controlling the NaCI input with recovered bleach plant effluent, and iii) changing metallurgy of a portion of the bottom section of the final stage superheater platens from ferritic steel T-22 (2.25% Cr, 1% Mo) to austenitic steel Incoloy 800H (21% Cr, 32% Ni, 46% Fe, 1.5% Mn, 1% Si, 0.6% Al) (Fig. 1). Details of the superheater corrosion experienced in the closed cycle mil! have been reported in previous papers(l ·2,) ."

Jan 1, 1984

By D. Laguitton

"Mathematics, process theory, process practice and computer applications are the main disciplines that contribute to developing useful techniques for computer simulation of mineral and coal processing plants. As in any multidisciplinary effort, communication or transfer mechanisms must be developed to facilitate the flow of experience between participants of different backgrounds. These mechanisms include written reports, verbal communications, workshops and transfer of computer programs. The SPOC project at CANMET is devoted to computer simulation and as such has addressed, or will address in the near future, problems inherent to methodology transfer. The first major output of the project was the material balance program, MATBAL2, which has been acquired by over 30 organizations. Program documentation, industrial workshops and summer student programs have been used to effect the transfer. This experience is discussed and the future outlined.IntroductionComputer simulation has become a common tool in many different fields of human activity during the past two decades, as illustrated in Figure 1. The total number of articles abstracted in Chemical Abstracts under the general subject entry of “Simulation"" has been following a pseudo-exponential growth since 1972 and was approaching 5000 in 1980, whereas no such entry was even used prior to 1967. This represents over a dozen papers published daily on the subject and should continue to grow to higher figures. Still, progress toward accepting modelling and simulation in mineral and coal processing has been very slow. It will be shown later that this slow acceptance is a cause rather than a consequence of the limited success of the various attempts made so far to draw unambiguous benefits from simulation applications. The real cause of the difficulties in fully accepting the new methodology lies in the multidisciplinary aspect of modelling and simulation, which does not suit the traditionally conservative approach that prevails in designing and operating large and costly processing plants."

Jan 1, 1982

By Marcel Vallée

"This text consists of two parts, comments on "Classification and Reporting of Mineral Resources for High-Nugget Effect Gold Vein Deposits," by S.C. Dominy, P.R. Stephenson and A.E. Annels, Volume 10, No. 3, pp. 215-233, and related comments on some features of the JORC Code.This paper is, in many respects, a very elaborate and valuable account of the problems encountered in the estimation and classification of high-nugget gold deposits. However, in some key areas, it appears to fall short of its objective to help "resolve satisfactorily most issues" and "contribute to improved estimation and classification" (abstract). One must realize that high-nugget effect gold deposits constitute a very narrow field, despite the occasional bonanzas. This is a field of mostly smaller sized deposits, where limited success and a significantly higher rate of failure occur relative to larger deposits of mostly lower grade. This is shown by the six deposits described in the paper. Thanks for contributing to greater understanding of these complex and nevertheless challenging deposits."

Jan 1, 2002

By T. Boyd, K. McTaggart, J. Qiu

"Hudbay Minerals’ Flin Flon process plant produces a copper concentrate and zinc concentrate from the three ores it processes: 777, Reed and Lalor. Unlike many Cu-Zn ores, the average Zn: Cu ratio in feed is around 2:1, whereas, in many Cu-Zn separation plants the Zn: Cu feed grade is substantially higher than 2:1. The lower Zn: Cu in plant feed is a challenge for limiting Zn recovery to the Cu concentrate. While total recoveries of Cu and Zn at Flin Flon are very good; selectivity is the key challenge and small changes in ore or plant, can result in quite variable Zn recovery to Cu concentrate, and accordingly, Zn recovery to Zn concentrate. Magnetic conditioning has been shown to be selective between the two paramagnetic minerals chalcopyrite and sphalerite. Statistical testing of magnetic conditioning was undertaken at Flin Flon with the objective of increasing Cu recovery to Cu concentrate without increasing the Zn recovery to Cu concentrate - in effect increasing Cu-Zn selectivity. This has been achieved elsewhere with magnetic conditioning with the probable mechanism being an increase in fine chalcopyrite recovery, and a reduction in entrained, ultrafine, non-activated sphalerite to Cu concentrate. The results did indeed show an increase in Cu recovery to Cu concentrate of 0.8% to high confidence, but the decrease in Zn recovery to Cu concentrate was not to high confidence. This is effectively an increase in Cu: Zn selectivity in the Cu circuit – higher Cu recovery with no change in Zn recovery. However, while there was an increase of 1% in Zn recovery to Zn concentrate with magnetic conditioning, the variability in this parameter meant that this increase, though larger in magnitude than the Cu result, was not to high confidence."

Jan 1, 2019

By Kostas Fytas

Acid mine drainage (AMD) is a serious environmental problem that preoccupies the Canadian Mining Industry. Considerable amounts of money are spent every year in an effort to prevent or reduce the acid mine drainage phenomenon. AMD occurs when sulphide minerals (ex. pyrite) contained in rock are exposed to air and water and subsequently oxidize to produce low pH water. This acid effluent has the potential to mobilize any heavy metals contained in the rock. Coating the sulphide minerals with silicates is a new promising technology to reduce AMD. Pyrite is treated with a solution containing H2O2, sodium silicate and a buffering agent. H2O2 oxidizes a small part of pyrite producing ferric iron (Fe3+) ions. These ions subsequently react with the silicate ions to produce ferric hydroxide-silica that precipitates on the pyrite surface producing a passive coating. This silicate coating can protect the grains of pyrite from oxidation. This paper presents a series of experiments that confirm that silicate coating can considerably reduce AMD.

May 1, 2001

By J. W. Hendry

"This paper will discuss the application of tools and the evolution of computer-assisted procedures in the production planning process at Quintett e Coal Limited (QCL). In 1986, QCL produced 5.3 Mt of clean coal from their surface mining operation located in north eastern British Columbia. The structural complexity of the sedimentary deposit and high rate of mining necessitate the consideration of large amounts of geological information which continually updates the interpretation. There are multiple unit operations required during the process of mining through a given multi-seam sequence, which results in many interdependent faces, and multiple iterations of scheduling sequences in order to satisfy a given set of objectives. In order to facilitate these activities in a timely fashion, it was recognized that a computer systems' capability needed to be developed which could increase the efficiency of information input, manipulation and output. IntroductionQuintette Coal Limited (QCL) has been operating a large metallurgical open pit coal mine in northeastern British Columbia, since 1982. The mine produced 5.3 Mt of clean coal in 1986 for export to Japan. Throughout the start-up period and the subsequent build -up of production levels, it became evident that the primary producing area was comprised of extremely complex faulted structures. This has resulted in development and modification of specialized mining methods employed to effectively recover the resource. Similarly, the planning and engineering techniques employed have been evolved over the same period of time. The implementation of computerized methods has been one of the major developments in this process, including geology interpretation, modelling, reserve definition, quantification, production planning and scheduling, and graphical plan presentation. These capabilities have been employed, in various forms, for project scale feasibility work and long range planning for some time, however, the use of computer tools for short-term, detailed production planning of a complex mining environment presents a different set of problems. It is hoped that a presentation of the current state of evolution and future plan s for development will be of interest to organizations considering implementation of a similar system."

Jan 1, 1988

By X. L. Song, G. W. Zhang, F. Y. He, X. Xiao, L. L. Huang

This paper presents the design of a model and process simulation of a vertical mill based on a population balance model. The simulator, Simulink, which is a systematic modeling tool within MATLAB, was used for the simulation. The model will simulate the real time variation trend of each size fraction in the feed material to the vertical mill, as well as, the size distribution of the batch grinding products. Breakage distribution and selection functions are calculated based on batch grinding laboratory experiments using Back-calculation method. The simulated size distributions correspond with those in the actual mill operation having a relative error of less than 0.50%. This work lays the foundation for future research on modelling and simulation of a closed circuit grinding operation consisting of a vertical mill with hydrocyclone classifier.

Jan 1, 2016

By G. P. Contractor

Many factors affect the forge ability of steels. One of the major factors is chemical composition.' This article discusses the individual effects of alloying elements and the effect of the resultant modification of microstructure onforgeability. INTRODUCTION T HE use of alloy steels is expanding considerably and the fabrication procedures for such alloys are becoming more complex. An attempt is made in this article to describe the effect of alloying elements on the hot-workability of steels. Most of the data reported here are taken from the studies of Ihrig, Clark and others (Refs. 1-4). Chemical composition is not the only controlling factor. Grain size and surface condition of the material, forging temperature, and speed of deformation are also important. Certain conclusions can be drawn regarding the effect of various alloying elements on the hot-work-ability of forging stock. The results of hot-twist tests are considered useful in this connection as the number of twists to failure has been taken as the level of forgeability at a particular temperature. The peak in the "Number of Twists -Tem--

Jan 1, 1962

The Daly-Judge Tunnel, begun in 1887 to drain mine workings, is now a source of potable water for the Municipality of Park City. The water is exceptionally clean; however, when roof falls occur, suspended solids levels become too high and water from the tunnel cannot be used in the treatment plant. In 2001, the tunnel was inspected and rehabilitated to ensure that the water supply for the 2002 Winter Olympic Games would be uninterrupted. Twenty-five timber tunnel sets were removed, and 86 steel sets were installed. Timber lagging was installed or replaced over about 230 m (750 ft) of tunnel length.

Jan 1, 2006

By S. C. Tadolini

"Roof bolts are the primary means of roof support in underground mines in the United States. Presently, post installation loads are measured on about 10% of the expansion anchor and combination bolts by using standard torque wrenches that Unit the accuracy of the measurements to about ±30%. No system has been available for measuring the loads generated on full-column resin grouted bolts. Mine roof bolts are long, slender, non-uniformly sized, roughly forged, and placed in a corrosive environment, creating obstacles for researchers trying to utilize ultrasonic reflection techniques to measure strain. A complete measurement system has now been developed by the U.S. Bureau of Mines, Denver Research Center. This system is being used successfully in determining loads measured on expansion anchor and combination bolting systems, examining the transfer mechanics of full-column, resin-grouted bolts, and measuring loads generated on bolts in an underground roadway support system.IntroductionMillions of roof bolts are used each year to provide structural support in underground U.S. metal, non-metal, and coal mines. Approximately 45% of the bolts used are expansion anchor, 45% are resin-assisted combination or full-column resin-grouted, and 10% are friction anchored. The effectiveness of these bolting types is dependent on a number of factors including rock density, bolt length, in situ stresses, rock properties, bolt pattern, installation tension, etc. When implementing expansion anchor and resin assisted combination bolts , installation and post-installation tension, or load, is a major determinant of support quality and subsequent behaviour of the reinforced roof. The method by which these systems carry roof loads is well understood and documented(1,2).The importance of these installation and long-term bolt tension measurements is well recognized and are required in the federal government regulations(3). A statistical sample of the bolts, lout of 4 during installation and lout of 10 inby the last open crosscut, is required to be measured using current torque wrench technology. The disadvantages of this system are the disturbance and weakening of the anchorage and limitations of accuracy to approximately ± 30%. The method by which resin-grouted bolting systems carry roof loads is much less understood, mainly because testing procedures used to evaluate point-anchor systems are not effective on resin-grouted bolts.Due to these problems, the U.S. Bureau of Mines designed a measurement technique that provided a highly accurate, low cost-per- bolt system that led to the development of ultrasonic pulse echo instrumentation. The original system was designed to measure the tension only on expansion anchor bolts. Recent developments and system modifications have permitted measurements on resin-assisted and full-column resin-grouted bolts. The use of these types of support systems has been increasing steadily in underground coal mines.The development of this instrumentation has provided laboratory and field results that help to explain the mechanics and relationships between the applied loads and the interaction between the grouted bolt system consisting of the bolt tendon, grout, and rock."

Jan 1, 1990

By K. Enns, J. J. Byerley

"While thiocyanate (SCN-) is used in a number of industrial processes (production of polyacrylonitrile filaments, synthesis of agricultural chemicals and certain metallurgical solvent extraction and flotation circuits) it is recognized more as an undesirable by-product associated with ' the metallurgical industry. Thiocyanate is present at low concentrations in some waste streams from the iron and steel industry. Of particular significance is the formation of thiocyanate during cyanidation of gold and silver ores, concentrates, tailing s and residues. The thiocyanate levels present in the resulting effluents may range from a few mg/I to several thousand mg/I.At present, thiocyanate does not appear to be as hazardous in the environment as cyanide (CN-) at the same concentration although its interaction with other species and resulting decomposition of products may be unacceptable. Of course the presence of thiocyanate in the leaching circuit and ultimately in the effluent streams may add considerably to the oxidative requirments of any non-selective treatment process for cyanidation wastes.With respect to the thiocyanate as it relates to the cyanidation process, two aspects are evident. Thiocyanate forms and persists in the cyanidation circuit resulting in a ""fouling"" condition with subsequent loss of leaching activity. In order to reduce or control this problem, it is common practice for some mills to discharge daily as much as 20% of the barren leach liquor. Besides contributing to fouling of the leach liquor the formation of thiocyanate represents an irreversible loss of reagent cyanide. It is noteworthy that in some present or proposed mill practice reagent cyanide loss through thiocyanate formation may reach 50%(1). The purpose of this paper is to discus s the application of controlled electrooxidation of thiocyanate with the view of suggesting a process for regenerating cyanide from waste thiocyanate(2). The paper describes the important theoretical aspects and presents experimental data obtained for thiocyanate electrooxidation using both small and large scale electrochemical reactors. Some economic conclusions are presented."

Jan 1, 1984

By Kenneth G. Thomas

Since approximately 2003 we have witnessed the unprecedented escalation in commodity prices. Coupled with economic chaos following the 2008 economic downturn this has caused difficulties in controlling schedule, capital costs and operating costs for mining projects. Once again escalation has returned to commodity prices fuelled by growth in the BRIC countries especially China and Brazil. This is further exasperated by the missing generation of skilled technical personnel not graduating from universities in the 1980s and 1990s owing to depressed commodity prices. This paper examines the six tenets for successful project implementation.

Jan 1, 2011