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By H. R. Manouchehri, A. Weh

"High voltage electric pulse comminution (SELFRAG) relies on inducing electrical breakdown that occurs when the resistivity of a dielectric is insufficient to completely block all transfer of electricity while the conductivity is not high enough to fully accommodate the flow of electricity without considerable changes to the crystal lattice. The technology is based on introducing the electrical discharges into solids immersed in water and placed between two electrodes. The technology has received significant attention since investigations have revealed the potential for fully fragmenting particles or pre-weakening rocks in order to reduce the energy consumption in comminution practices, improve liberation and potentially increase the recovery in mineral processing. Mineralogical analysis of samples showed possible liberation at coarser sizes by high voltage breakage in comparison with conventional mechanical comminution.This study explored the potential of implementing SELFRAG to treat the Sandvik’s Mittersill mine tungsten ore (scheelite) for recovery improvement. Accordingly, standard SELFRAG tests were conducted on four samples from the tungsten process plant to evaluate the energy-breakage relation and potential to liberate the value minerals at coarser size fraction for recovery improvement. The size reduction of the ore after processing with SELFRAG revealed that size deportment occurs at 0.4, 0.2, and 0.1 mm, which indicated potential liberation of gangue and target minerals at respective sizes. In comparison with conventional milling, the difference is the deportment of values into 0.4 mm sizes, which was, to some extent, confirmed by SEM liberation analysis. However, more tests are needed to proof the concept. The study has indicated that, despite consuming more energy in comparison with conventional mechanical comminution, there are promising prospects in liberating the values at coarser fraction and improve recovery by making use of SELFRAG. The energy consumption can be reduced through customized generator and equipment setup, which must be further investigated."

Jan 1, 2016

The mixer that is commonly encountered in hydro metallurgical operations consists of a single turbine and tank combination. However, it would be advantageous to examine some common solvent extraction mixing systems in the light of the fundamentals of chemical reactor design. The basic concepts of reactor design are commonly used in the chemical industry, and it should not be too difficult to apply them to solvent extraction. The factors that affect the engineering design of a reactor are: the reacting system; the type of reaction; and the configuration of the reactor. The reaction system in solvent extraction consists of a heterogeneous liquid phase, involving two immiscible liquids. It is essential f or the process that the reactor product can be separated efficiently in the subsequent settler. The type of reaction in solvent extraction system may be quite complex, and the picture is complicated by the presence of competing and side reactions. The reactors themselves have been generally continuous stirred tanks, and the nature of the mixer-settler makes it unlikely that the pumping mixer can be dispensed with. However, it appears that there should be some definite advantages to a system of stirred reactors in series. The kinetic experiments which are carried out should have the definition of optimum reaction conditions as one of their goals. The data obtained from these experiments must also be applicable to the design of reaction equipment. Reactor selection and design is often a unique problem for each chemical process, and does not lend itself to a systematic general approach. However, the application of chemical and physical principles to mixer design in solvent extraction should result in practical, more efficient plants.

Jan 1, 1979

By Simon Houlding

"The objective of Part J of this paper is to identify the limitations of the traditional modelling methods and to illustrate, by example, the potential for error created by their application to complex deposits and mining situations. Part 2 describes the evolution of new, proven technology which eliminates these deficiencies and provides precise and practical alternatives. These promote the use of realistic geological and mining shapes and eliminate altogether the rectangular approximations of traditional methods.The Case for Precision ModellingIt is not the intent of this paper to promote the benefits of computer modelling per se. It is assumed that these are recognized by the mining industry in general. The concern of Part 1 is to identify, qualify and quantify (where possible) the limitations of the tractitional modelling methods. In many instances these methods continue to be applied to complex geological and mining situations for which they were never intended nor designed. The source and magnitude of the resulting errors, conflicts and inefficiencies are not always obvious, however, they can have far-reaching effects on the efficiency and profitability of mining operations.The conclusions support a rapidly growing demand by industry for practical, precise modelling technology which eliminates the deficiencies and can be applied with confidence to evaluation, design, planning and control of mine production in all situations. Part 2 describes new technology which has evolved in response to these industry pressures and has already been successfully applied to complex mining situations. This new technology can aptly be described as appropriate technology for the 1990s."

Jan 1, 1991

By Al Hoffman

During the period May 15 ? 17, 2006 four fatalities occurred at #1 Waste Dump, at Teck Cominco?s Sullivan mine located at the city boundary of Kimberley, British Columbia, Canada. The fatalities occurred in the sump of a water monitoring station. The Chief Inspector of Mines and his staff immediately responded to the incident. The team worked collaboratively with the Teck Ltd. Trail Hazmat team, a consultant group from Rescan Ltd. and other Teck operation and technical staff. Sampling in and around the water monitoring station in the days following the fatalities showed that exposure to a depleted oxygen environment was the immediate cause of the fatalities. The sump located at the base of the shed was hydraulically connected to a French (coarse rock) drain, located at the toe of the covered waste dump. This presentation will briefly review the immediate cause of the accident, the investigation, a brief introduction to the work of the Sullivan Technical panel and the British Columbia government?s response to the incident and the recommendations of the Coroner?s inquest.

May 1, 2010

By Tony Lipiec, Ian Orford

"A key part of plant design is the selection of the design tonnage which is the hourly tonnage target that the equipment selection is based on. Its selection is critical for ensuring that the nominal tonnage which is critical to the financial performance of the project will be met. With deposits being developed at lower grades, higher tonnages and a higher degree of hardness variability, it is essential to ensure that the design process selects the comminution equipment which will be able to deal with the impact of this ore quality variation.Ore hardness and its variance are key factors to be taken into consideration for the selection of the design tonnage. It is well accepted that for the nominal or name plate tonnage to be consistently achieved, it is necessary to base the design tonnage on a hardness value greater than the average ore hardness of the deposit to be mined. The question is how much greater should this design value be to ensure that the nominal tonnage is met to the satisfaction of the project financial model. Standard industry practice is to set the design tonnage by:1. Select an ore hardness percentile that is greater than the average ore hardness to be the basis of the nominal tonnage. Typically either the 75th or 80th percentile value from the data set will be selected.2. Selection of a design factor to multiply by for determining the design tonnage, i.e. the design tonnage = tonnage (based on the average ore hardness) multiplied by design factor.This paper discusses the selection of the design ore hardness through the use of modelling or the use of a design factor. It further shows the impact of ore hardness variance on the capacity of the process and its ability to meet the nominal tonnage. Insight is provided as to what ore hardness percentile value should be selected balancing the shortfalls of tonnage for ores harder than the design value versus the above target production achieved for ores softer than the design ore hardness."

Jan 1, 2016

By H. K. Fredrickson

"Midwest Joint Venture (MJV) owns a high-grade uranium deposit in northern Saskatchewan. The deposit is located too deep below surface to be mined economically by open pit methods, and as a consequence, present plans are that it will be mined by underground methods. High-grade uranium ore of the type at MJV, encased in weak, highly altered ground and with radon-rich water inflows, has not before been mined by underground methods.The test mining phase of the project, completed in 1989, had three objectives: 1. to evaluate radiation protection requirements associated with the handling of large quantities of radon-rich water and mining highgrade uranium ore in an underground environment; 2. to investigate the quantity and quality of water inflows into the mine; and 3. to investigate ground conditions in and around the ore zone as an aid in determining the production mining method to be used.With information gained from the test mining project, a mining method for the production mine has been devised. Level plans have been drawn up, ventilation system designed, pumping arrangements made and methods of ore handling considered. All this is to be done in a manner that will be safe for those doing the work underground. Some of the mining methods planned are felt to be unique in that they are designed to cope with mining problems not known to have been encountered before. New problems underground have required new methods to handle them. Remote drilling, blasting, mucking and backfilling form the basis of the planned mining method."

Jan 1, 1992

"Ground control research in underground coal mines has been ongoing for over 50 years. One of the most problematic issues in underground coal mines is roof failures associated with weak shale. This paper will present a historical narrative on the research the National Institute for Occupational Safety and Health has conducted in relation to rock mechanics and shale. This paper begins by first discussing how shale is classified in relation to coal mining. Characterizing and planning for weak roof sequences is an important step in developing an engineering solution to prevent roof failures. Next, the failure mechanics associated with the weak characteristics of shale will be discussed. Understanding these failure mechanics also aids in applying the correct engineering solutions. The various solutions that have been implemented in the underground coal mining industry to control the different modes of failure will be summarized. Finally, a discussion on current and future research relating to rock mechanics and shale is presented. The overall goal of the paper is to share the collective ground control experience of controlling roof structures dominated by shale rock in underground coal mining.INTRODUCTIONThe National Institute for Occupational Safety and Health’s (NIOSH) Office of Mine Safety and Health Research (OMSHR), formerly the United States Bureau of Mines, has been conducting research on ground control safety for over 50 years. The overall objective of the research is to reduce underground mining injuries and fatalities by characterizing roof conditions, improving roof support performance and application, and optimizing pillar design and mine layout. Underground mining has one of the highest fatal injury rates of any industry in the United States—more than five times the national average compared to other industries (CDC, 2012). Roof fall injuries can be severe, resulting in lacerations, bone fractures, amputations, and death. Non-injury roof falls can also be problematic, resulting in lost production, delays, blockage of primary escape routes, disruption to ventilation, and hazardous rehabilitation conditions.Coal mining is increasingly subject to more adverse geological conditions. Weak roof can be found in all coal mining regions in the United States, but there are a few geographically isolated areas with higher roof fall rates contributed to by particularly poor roof conditions, as represented in Figure 1. This figure shows that when non-injury roof fall rates are normalized to production, the Illinois Basin and Central/Northern Appalachia regions have the highest rates. These isolated regions have inherently weak roof even before mining has occurred, and this roof is easily damaged during the mining process. The weak roof in these regions consists primarily of shale. Shale can be troublesome in underground coal mining because it can appear massive but easily splits along bedding planes and is often moisture-sensitive."

Jan 1, 2015

By Helmut Ehnes

Over 330 million accidents at work happen world wide every year, only counting those leading to more than four days absence. More than 350,000 end fatal. Two million people more die every year due to work-related diseases. To sum this up: around 2.4 million people die every year because of work conditions. Among many risky industries, mining stands out. While mining represents just 1% of employees globally, it unfortunately represents 8% of all occupational fatalities. Mining operations go along with a variety of hazards. Not only in large operations, as they first come to mind, but also in the manifold small scale mines, with an estimated 13 million labourers worldwide exposed to substances such as dust, mercury and other chemicals, while also dealing with poor ventilation, inadequate space and overexertion. But is the number of severe accidents and diseases inevitable or can we change this situation? We can make mining sustainably safer, but we need a successful strategy to do so. A high potential lies in Vision Zero. Vision Zero is a prevention strategy for a safe future without fatal or serious occupational diseases, work accidents and traffic accidents. First defined as early as in the 19th century by Eleuthère Irénée du Pont, its very successful elements were adopted by many European countries first aiming at road safety, then extended to safety and health at work. Vision Zero?s holistic elements cover technology, workplaces, rules, and people as fields of action. By focussing on severe and fatal accidents, its application increases the level of safety and health overall.

Aug 1, 2013

By Rachel S. Prudhomme, Michael L. Jeremic

"The consolidation of mine backfill by free zing is a concept which has been under study in the mining engineering laboratories at Laurentian University during the past three years. The proposed underground application of freezing involves the artificial freezing of in-situ backfill by means of a refrigerated brine solution which would be circulated through a circuit off freeze pipes. The most interesting findings to date are: (I) The uniaxial compressive strength off frozen fill is considerably higher than that of cemented fill in a ratio of 20:1 (aggregate to cement), and (2) load deformation characteristics of the frozen fill suggest that a higher ice content results in more brittle failure and that samples which have initially failed can still support up 10 one-half the ultimate load without additional failure.Although at this early stage a derailed economic analysis of the procedure has not been possible, a general evaluation of the costs involved suggests that the method could be competitive with the hydraulic placement of cemented backfill. Results obtained from laboratory investigations indicate that the freezing of backfill is a structurally feasible option .IntroductionGround consolidation by freezing is based on the principle of transformation o f water contained in an aggregate-slurry into ice, which act s as a binding agent between the bulk particles, and which results in the transformation of a granular soil into a ""rock -type"" material. The abrasive nature of the particles enhance s the strength o f the ice by providing internal friction. As a result of this internal friction, the chances of plastic flow of the frozen mass when in a loaded condition are reduced(1). T he strength of a frozen aggregate is al so dependent on the grain shape of the aggregate particles which may or may not promote particle interlocking(2) and on the temperature since, below the freezing point of the water/aggregate mixture, the strength of the frozen mass increase s with decreasing temperatures.In the shaft sinking industry, artificial freezing of loose , unconsolidated soils has been in practice for several decades. Shafts for Saskatchewan 's potash industry have been sun k to depths of 3000 feet by employing artificial freezing to stabilize the Blairmore Formation(3). The common procedure for freezing ground for shaft sinking is summarized as follows(4,5): I) 150 mm diameter bore holes spaced on 1.5 m centres are drilled in a circular pattern with a radius of 1.5 m outside the periphery of the proposed shaft."

Jan 1, 1985

By Michel Garon

"Several years ago computer control of the flotation process was successfully implemented at the Matagami concentrator of Noranda Mines Inc. At that time this was the first computer application being installed at this operation. The last few years have seen an extensive use of programmable controllers in areas such as the copper and zinc dewatering circuits and the lime preparation system. With the aid of such instruments, these areas have attained a high level of automation and as a result, a high degree of efficiency. The controllers have proven to be very dependable and easy to use.IntroductionThe Matagarni Division of Noranda Mines Inc. operates two mines in the Matagami District of northwestern Quebec which is located about 650 km northwest of Montreal. The mines ship ores to a central concentrator whose throughput averages 95,000 tonnes of ore per month. Metal contents of the mill feed average 0.9 per cent copper and 5.0 per cent zinc. Concentrate outputs are approximately 3,200 tonnes of copper and 8,200 tonnes of zinc per month.The concentrator commenced operation in 1963. An on-stream X-ray analyzer was installed in 1968, providing analyses of several samples in the flotation circuit without the aid of a computer. In 1974, control of the circuit by computer was added to the system. As a result, zinc flotation efficiency improved considerably and reagent costs decreased through the reduction of copper sulphate consumption.In the past few years it was realized that significant improvements could also be made in other parts of the operation . Copper and zinc dewatering circuits and the lime preparation system were identified as major areas that could drastically benefit from automation. In 1982, programmable controllers were seriously considered as an attractive alternative for achieving the company 's goal. Because of their relative lowcost and their high degree of flexibility, they were selected for implementing automation and, for improving the efficiency in each of these areas."

Jan 1, 1985

By M. Korchynsky

"The key words which characterize vanadium are: unlimited availability, versatility of applications and price stability. The supply of vanadium is assured by diversified sources, distributed all over the globe. The inexhaustible raw materials base is complemented by a strong vanadium industry. Both the fully integrated vanadium producers and converters of vanadium oxide or vanadium-containing slags or residues guarantee an adequate supply, commensurate with the steady growing demand.The major share of the world's vanadium output is being consumed by the steel industry. As an additive to steel, the versatility of vanadium is particularly impressive. A few hundreds of one per cent of vanadium convert plain carbon steel into high-strength, low-alloy steel with more than double strength. On the other extreme, high-speed steels made via the powder metallurgy route show superior performance with vanadium additions as high as 6 or 8 percent. Vanadium is used as a cost-effective alloying addition in steels for high-temperature service, fully alloyed heat-treatable steels, new dual-phase steels for automotive components, rail steels, etc., to mention only a few applications. Vanadium is also an established essential addition for titanium alloys. The chemical industry is relying on vanadium compounds as important catalysts.In spite of a wide diversity of applications and continual growth in consumption, vanadium has exhibited, over the past several decades, a remarkable price stability, free of conjunctural fluctuations. Because of its availability and versatility, it will continue to be one of the key metallic elements for future technologies.Key Features of VanadiumIn attempting to single out the key features of the metallic element vanadium, three descriptive characteristics come to mind: availability, versatility and price stability."

Jan 1, 1982

By Robert B. Parsons

"The Canadian Exploration Incentive Program (CEIP), which was announced by the federal government on May 3, 1988, promises to maintain the viability of flow-through shares as a financing mechanism which has proven to be so crucial to the health of the junior exploration sector. This month, Tax Notes examines, the main features of CEIP, which will come into play on January J, 1989. IntroductionOn May 3,1988, the Honourable Marcel Masse, Minister of Energy Mines & Resources, and the Honourable Gerald Merrithew, Minister of State (Forestry and Mines) announced the Canadian Exploration Incentive Program (CEIP). Under CEIP, the federal government will make cash payments to eligible applicants equal to 30% of eligible exploration expenses. CEIP payments will be available with respect to both mineral, and oil and gas, exploration. In essence, the program will replace the ""mining exploration depletion allowance"" (MEDA) presently applicable to mineral exploration, and the Canadian Exploration and Development Incentive Program (CEDIP) which is presently available to the oil and gas exploration sector.This paper discusses briefly the main features of CEIP insofar as the program will affect mineral exploration. The comments herein are based on the Canadian Exploration Incentive Program Act which received Royal Assent on July 21, 1988, and on a discussion paper which was released by EM&R in May 1988. The bulk of the rules relating to the program will be in the form of regulations which have yet to be finalized. It is understood that EM&R would like to have the regulations in force by October I, 1988, when the oil and gas portion of CEIP becomes effective. (The rules relating to mineral exploration will become effective January I, 1989)."

Jan 1, 1988

By William Petruk

Mineralogical investigations in connection with gold metallurgy are usually performed to find the reason for poor recoveries by cyanidation or by other leaching techniques. Poor recoveries most commonly are obtained when (I) native gold is encapsulated in an insoluble mineral as "invisible gold"; (2) native gold is coated with a precipitate; (3) gold-bearing products are insoluble in cyanide solutions; (4) carbonaceous material in the ore adsorbs gold; and (5) associated minerals decompose and consume cyanide. Samples of refractory material quite often have low gold tenors. It is difficult to find the gold-bearing minerals in such samples with an optical microscope because the probability of finding trace minerals in samples is small. The probability decreases with decreasing grain size of the gold-bearing mineral and with decreas¬ing gold tenor of the sample. Techniques have been developed to increase the success rate of finding gold grains; some are (1) concentrating heavy minerals; (2) preparing special polished sections; (3) searching with an image analyzer; and (4) dissolving associate silicate and sulphide minerals.

Jan 1, 1989

By Ross G. Bertinshaw

"The Line Creek Mine of Crows Nest Resources started mining coal in the fall of 1981. There are seven mineable seams with thicknesses ranging from 1.5 to 13 metres and with dips varying from 0 degrees to 60 degrees. This, together with internal partings and the very friable nature of the coal, creates a number of mining problems.The coal is divided into zones depending on the dip of the seam. Each zone requires a different mining technique to ensure optimum recovery and low dilution while still keeping fines to a minimum.Line Creek employs a combination of hydraulic front shovels and backhoes to mine its coal without blasting or use of dozers. This has been very successful in reducing the proportion of fine coal hauled to the plant, thus improving quality control and reducing costs in coal processing.There have been a number of other benefits from the use of excavators instead of more conventional methods. These include better selectivity, good cleanup, reduction in traffic at the face and lower cost.IntroductionThe Line Creek Mine is situated approximately 25 km north of Sparwood in southeastern British Columbia (Fig. I). Preproduction stripping began in J98J with the first coal shipments made in 1982. In 1983 the mine produced 2.1 million tonnes of raw coal.Similar to other East Kootenay coals, the seams at Line Creek are characterized by their friability, producing a large proportion of fine coal during mining. In an attempt to reduce these fines Crows Nest Resources has instituted the use of hydraulic excavators to mine and load the coal.Hydraulic excavators offer other substantial advantages over front-end loaders and dozers, which has been the conventional system in other mines in the area."

Jan 1, 1985

By Per-Lennart Nystedt

"The Boliden Lead Kaldo Plant for the treatment of lead bearing flue-dust from the Copper Smelter and the Slag Fuming Plant has been in operation at the Ronnskar Works of Boliden Metall since the middle of 1976. At the present stage, the plant can treat lead-bearing dust of different kinds and compositions. The process allows good separation of arsenic and halogens from lead.The flue dust from the Copper Smelter and the Slag Fuming Plant is very complex and, apart from lead, also contains zinc, copper, tin, bismuth, cadmium, antimony, arsenic, sulphur, silver, chlorine and fluorine. The metallurgical process has been developed by Boliden Metall and has been tested on a pilot scale at the Foundation for Metallurgical Research (MEFOS) in Lulea, Sweden.The pelletized dust is smelted in the converter, where the heat is generated by an oil oxygen burner. The second step consists of reduction with coke. A lead bullion and slag are obtained. The slag, transported in liquid form, is treated in the Slag Fuming Plant for the recovery of zinc. The third step is the elimination of arsenic from the bullion. This is achieved by treating the lead with iron (turnings or pellets). The result is a crude lead and speiss. The lead contains silver, tin, antimony and bismuth, and is suitable for the final refining stages in normal plant equipment for refined lead.For process control, we use the rapid analysis centre, which is pneumatically and electronically linked to 'all major plant sections and allows for a quick turn-around between delivery of the sample and feedback of results. All three steps in the process are performed in the same converter.Since the starting up of the plant, the original process has been subjected to some modifications. Initial problems related to equipment, maintenance and environment have been solved step by step. Examples are quoted. Recent operating particulars are presented."

Jan 1, 1980

By Lynn C. Fister

"Coal is rapidly becoming a major alternative to oil. According to the World Coal Study Final Report, total world coal trade could approach one billion tons annually by the year 2000. To facilitate the increased production and export market potential of the coal producing countries, advancements must be made to improve the transportation systems. Coal slurry pipeline systems could play a significant role in achieving these market forecasts.There are three major components to a coal slurry system the preparation plant, the pipeline and the dewatering plant. The experience and expertise gained from the Consolidation Coal Company system in Ohio, the Black Mesa system in Arizona and ETSI's Coal Evaluation Plant demonstrate that slurry pipeline technology is proven and available to meet the coal transport challenge.The costs of transporting coal by slurry pipeline can offer significant savings, as about 70 per cent of its costs are fixed. The reverse is true for railroads, where 75 to 80 per cent of the costs vary with inflation. All forms of transport-rail, barge and pipeline-will be required to move the massive volumes of coal. Coal slurry systems can provide a viable transport alternative.IntroductionThe importance of coal as a major alternative to oil is now well known and accepted throughout the world. Increasing oil prices over the last eight years have had a serious effect on national economics, particularly in those countries that are heavily dependent on oil. Coal can replace oil as the principal fuel source which could support world economic growth over the next two decades. This is the main conclusion of the World Coal Study (WOCOL) Final Report, published in May 1980.The product of that report was a result of considerable deliberation by key industry leader s and energy experts. The underlying message of the World Coal Study is that our energy and economic problems can be faced with confidence if coal use doubles by the early 1990s and triples by 2000, and if steam coal trade expand s considerably."

Jan 1, 1982

By Mario Giavani

"IntroductionBy the 1980s, the continuous casting process had almost replaced the ingot casting of steel in Japan, Europe and North America. While economic benefits were probably initially the prime motivator, the transition rapidly proved that continuous casting in conjunction with ladle metallurgy offered a much greater degree of process control and made possible routine steel specifications not previously available.This new technology demanded improved procedures for the quantitative addition of the required metallurgical reagents, especially as regards the more volatile or toxic elements such as calcium , boron, carbon, sulphur, lead and tellurium. The injection of a thin steel tube containing the additive into the metal bath of a ladle refining station offers the best procedure for this. In the industry this has been referred to as ""Cored Wire "".Operators using this technology find that they are faced with balancing the injection speed against the small cross section of the tube to feed the required amount of reagent within the short time span available to the operation. Large-ladle shops requiring major quantities usually resort to multiple machines and high speeds. Many machines approach a maximum feed rate of 400 m/min. Higher speeds exceed the melting rate of the system, and the ferro static buoyancy of the tube will cause it to coil up the ladle wall and possibly resurface into the slag layer, and even eject itself above the surface. Under these conditions, exact control of element recovery becomes difficult, especially with the commonest addition, calcium silicon alloy.Many experts are persuaded that the final melting position of the carrier tube has major importance in establishing consistent element yield to the bath.For instance, the vapour pressure of calcium at l500 °C is close to I bar. Reaching a melting depth sufficient to accommodate this value is considered to be critical to achieving an acceptable and reproducible yield.Many studies have elaborated semi-empirical formulae to establish the melt zone depth, connecting this value essentially to the diameter of the tube , the injection rate and the superheat of the steel. The author's experience in steelmaking could not confirm such formulae in many cases, and he set about to develop a mathematical model which would be useful in addressing this problem, taking into account the several parameters which will regulate the behaviour of a filled tube immersed in molten steel."

Jan 1, 1991

By Gerhard Melcher, Hermann Hilbrans, Michael Gamroth

"IntroductionSeveral new smelting processes have been proposed and developed during the last 20 years. This has been true, in particular, for copper smelting technology. The important impulses for the advances in this field have been the recent demands regarding the environmental protection, energy saving and improved utilization of the metals contents of deposits, in particular that of complex raw materials.The methods developed more recently for pursuing these objectives have been outlined in several papers. In some of them the advantages and drawbacks of certain developments have been stressed. These documents are of great importance for assessing the different processes. The following paper tries to explain some details of the cyclone smelting process taking into consideration a few of these well-known presentations. The effectiveness of operation of the cyclone smelting process indicates that this process presents a significant achievement when compared with other conventional methods.The application of the CONTOP smelting cyclone range s beyond the field of copper metallurgy or the smelting of sulphide concentrates with the aid of oxygen. The research work carried out in the pilot plant of KHD Humboldt Wedag AG in Cologne-Porz also includes the recovery of the metal contents of intermediate products and processing of smelter residues which have to be converted in a disposable stat e, free of environmental pollution. This paper explains a few examples in this regard."

Jan 1, 1987

By C. Gravel, A. Fathi, P. Rivard, G. Ballivy, Z. Moradian, M. Quirion

Knowing shear mechanism of discontinuities under monotonic and cyclic loading conditions is a key factor in stability analysis of rock slopes and rock foundations. In this paper, the effect of cyclic loads on the shear mechanism of joint asperities is described. For this purpose, a fresh tension-split joint from a granite block was used as a reference and thirty five mortar replicas were fabricated. Cyclic shear tests were conducted on replicas under low values of constant normal load (CNL) using a servo-controlled loading system. Tests were performed in two consecutive steps; load-controlled and then displacementcontrolled. In the load controlled part, after initial increase of shear stress to 0.25 MPa, the test was stopped for 2 minutes, then increased to 0.5 MPa, and finally decreased to 0.25 MPa. This process was repeated ten times. At the end, the test was continued up to 10 mm shear displacement under displacement-controlled loading in order to pass the peak shear strength and reach the residual strength. Characterizing joint surface and modeling of involved asperities during the tests was undertaken using a Matlab code developed with new mathematical expressions. The algorithm used in the code is based on three-dimensional coordinates of the scanned joints’ surfaces before and after the test. It was found that a high percentage of degradation happens during the first cycle of loading and during the other cycles, degradation occurs gradually. While comparing tests conducted in monotonic and cyclic loading conditions, it was observed that under low number of cycles, the pronounced mechanism is consolidation of the joint surfaces. This consolidation increases contact areas and, therefore, shear strength parameters.

Jan 1, 2015

By E. J. Marcotte

"INCO LIMITED'S Shebandowan Mine and Mill is located in a scenic tourist and cottage area near the western tip of Lower Shebandowan Lake, approximately 90 Km west of Thunder Bay, Ontario. This nicely designed complex is a positive indication that mining operations can co-exist in harmony within the natural environment.The Shebandowan complex processed nickel-copper ore from 1973 to 1985, inclusive, after which operations were shut down.In late 1988, INCO LIMITED decided to place the Shebandowan complex back into operation, under contract, to mine and mill the remainder of the ore body, according to their specifications. MaclSAAC'S EXPLORATIONS was the successful bidder for the project. Following preliminary rehabilitation, operations were re-activated in late March, 1989. The ore mined to date is of a moderately lower nickel grade than the majority of previous years. However, a higher tonnage rate, combined with improved nickel recoveries, has contributed to a viable operation.A series of mill operating and equipment modifications has enabled MaclSAAC EXPLORATIONS to achieve the quality and grade of nickel-copper concentrates specified, and at the same time, expand mill tonnage throughput while attaining increased nickel recovenes."

Jan 1, 1992