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By D. E. M. Plaumann

"The wet grinding of asbestos has attracted the attention of engineers for many years as a means of improving fibre liberation from the ore. Today, added impetus for wet grinding has resulted from a need to minimize worker exposure to asbestos dust in conventional dry mills using air, as well as a need to provide a cleaner, technically superior fibre for use by product manufacturers. However, high viscosities of asbestos slurries create transport and grinding difficulties which have been a factor impeding use of a wet grinding process.Laboratory evaluation of reagents to reduce viscosities of asbestos slurries found that one reagent, XFS-4272.00, reduced the viscosity of a 35% (by weight) slurry by 75%. The impact of XFS-4272.00 on actual grinding parameters were evaluated using a pilot plant rod mill. Slurries containing 78% solids and XFS-4272.00 were successfully milled and asbestos fibres from that milling compared favourably in liberation and relative surface area to asbestos fibres obtained from milling a 4% slurry without additives. IntroductionAlthough the use of asbestos has been declining over the last few years, the large deposits of chrysotile in eastern Canada (Quebec in particular) remain very important. Asbestos production in Canada stands ninth in volume for mineral production with over 740 000 tonnes produced in 1985. Of this quantity, 722000 tonnes were exported with a value of $446 million. Canada is second in world production of asbestos behind the U.S.S.R. The milling of asbestos ore has been done primarily by a series of steps involving crushing, dry-grinding and aspiration using large quantities of air to release the fibres. Contrast this process to those practiced in the purification of virtually every other mineral. Ores other than asbestos are crushed and milled using an aqueous slurry in rod, ball or pebble mills. The finely ground mineral, still as a slurry, undergoes beneficiation by froth flotation, heavy media separation, hydrocyclones or any of the other aqueous techniques currently employed in mineral processing.One of the driving forces behind the use of air instead of water as a means of separating asbestos is the nature of the aqueous asbestos slurry. While most slurries of minerals contain as much as 80070 solids and can still be pumped and transported, asbestos slurries become highly viscous with as little as 10070 solids. These high viscosities reduce the pumpability of the slurry and create severe handling problems. Mills become prohibitively large and uneconomical due to having to handle slurries containing only 10% rock and 90% water.Health-related issues have affected the use of asbestos in many countries. In Canada, the asbestos-producing provinces have introduced stricter occupational legislation to improve safety in the workplace. This primarily means strict control minimizing release of air-borne asbestos fibres . Quebec and Ontario have set limitations of airborne asbestos at 2 (2) and 1(3) fibre per cubic centimetre of air. With present milling technology, maintaining these low levels in the workplace requires constant vigilance."

Jan 1, 1988

By M. P. Brameld, R. H. McCorkell

"Overburden covering bedrock uranium deposits was sampled to depths of 29 m and Rn concentrations measured at the same depths. Total-alpha activities, V concentrations and Rn emanation (J) of the samples were measured. The U-flux into the overburden was greater in the past: oxidation and dissolution has since removed most U, leaving decay products which indicate the presence of U deposits when U itself does not. Distributions of U and decay products and their ratios to each other reflect U-migration and degrees of U-removal. Rn distribution in overburden is related to the J of overburden samples and the presence and movement of groundwater. Simple, rapid methods of total-alpha and J measurement are described.IntroductionThe overburden drilling apparatus developed by Bondar-Clegg and Company makes possible sampling and radon measurement in overburden from the surface down to about 50 metres. This apparatus was used here to study the diffusion of uranium and its decay products from ore deposits into over lying overburden at the N deposit of the Amok Ltd. property (Cluff Lake, Saskatchewan) and on the Imperial Minerals Ltd. property at Gooderham, Ontario. These ores are enclosed in bedrock; the overburdens were deposited by glaciers or streams. The migration of uranium and its decay products in such situations and the factors which affect it have been little studied in the past, as readily usable techniques for mapping it in three dimensions have not been available. The results reported here are somewhat sketchy and preliminary, but they indicate the value of the methods used and some of the patterns to be expected. Surface and subsurface sampling and measurements were carried out on 3-line grids crossing known zones of mineralization. The lines were 60 metres apart at Gooderham and 40 metres apart at Cluff Lake."

Jan 1, 1982

By W. Cholewa, T. S. Golosinski, J. Wedzicha

"Power requirements of belt conveyor drives are usually estimated based on the calculated belt tension which equals the sum of unit resistances to motion which the belt has to overcome. In most situations, the value of various unit resistances can be accurately predicted using published information (5,6,8,12). A simpler approach calls for use of standard formula and tabulated values of related factors which reflect various features of both the conveyor and the transported material (2,3,7) . None of these approaches is reliable when materials with unique properties are conveyed, nor if applied to conveyors working in extreme climatic conditions. Such is the case of oil sand mines in northern Alberta.There the bitumen content of oil sand causes it to behave in a unique manner. Furthermore the conveyors operate year around, with winter temperatures often lower than - 40°C. It was the objective of presented investigations to quantify the power requirements of conveyors, and related resistance to motion for the conveyors used in oil sand mines during winter operations.The other objective was to quantify the drive power requirements of oil sand conveyors during start-up. These requirements are usually much higher than those during norm al operation, and their quantification is of paramount importance for operation of large conveyors."

Jan 1, 1992

By J. W. M. Porritt, M. P. Brameld, R. H. McCorkell

"Soil-gas Rn was measured by two types of alpha-particle-track detectors, by emanometry and by counting alpha-activity on Rn-decay-product collectors. Soil samples were analyzed for V by fluorimetric and fission-track methods, their Rn-emanation by decay-product collectors and their total alpha activities with track detectors. The same uranium anomalies were revealed by each method. Fission-track analysis of leaves for V showed only random variations with sampling site, and the Rn emanation of trees and leaves removed from them was barely detectable . The agreement among the other methods is significant, total alpha and collector methods are simple, rapid and useful, and a combination of methods at a site would reveal disequilibrium in the U-decay series if present. Track-Rn measurements are highly reproducible and insensitive to apparatus design and their sensitivity is not enhanced by covering the detectors with thin foil or placing them in large containers.IntroductionIn the past two years , a number of methods of geochemical exploration for uranium have been tested by the authors over the known copper-uranium occurrence at South March, Ontario. This was done partly to compare methods and partly to develop and test new ones. The South march deposit has been described a number of times by others(1,2,3,4). The methods included in this study were the following.Emanometry, Radon in soil gas is measured by pumping the gas into the cell of a scintillation counter or emanometer(5,6). Alpha particles from radon (222Rn) and its decay products (218Po and 214Po) produce scintillations of light in the silver-activated zinc sunphide (ZnS(Ag) covering the walls of the cell. These are counted by a photomultiplier tube and scaler, the count ra sulphide (ZnS(Ag) covering the walls of the cell. These are counted by a photomultiplier tube and scaler, the count rate being proportional to the concentration of radon in the soil gas."

Jan 1, 1981

By A. J. Keen

"Cominco's Polaris Mine is an underground lead/zinc operation located on Little Cornwallis Island in the Canadian High Arctic. Polaris is the world's most northerly base metal mine, situated at about latitude 75°N and longitude 97°W (Fig. 1). The closest community is Resolute Bay about 100 km to the southeast.During the construction and development phase Cominco adopted a unique scheme to save time and money. Many facilities including concentrator, powerhouse, shops and warehouse were built on a barge in southern Canada. The barge was towed 4800 km to the site in August 1981. Production at Polaris began in November 1981. The current mining rate is 1 million tonnes per year. The mine employs 250 people with about 190 on site at any time.GeologyThe deposit is a Mississippi Valley type orebody and lies near the top of the Ordovician Thumb Mountain Formation. Ore minerals consist of sphalerite and galena with the gangue being predominantly dolomite with calcite and marcasite. The orebody is situated completely within permafrost, consequently the voids frequently found in the ore are filled with ice. The orebody strikes north-south, dips approximately twenty degrees to the east and takes up an area about 400 m wide by 700 m long. The upper portion of the orebody (60 m to 150 m below surface) lies in an area called the Panhandle Zone. The deeper portion of the orebody known as the Keel Zone extends to 300 m below surface (Fig. 2). The deposit is strongly zoned with a high grade zinc/lead and iron-rich tabular core overlain and underlain by vein, stringer and breccia mineralization. The ore reserves at January 1991 were 14.6 million tonnes at 3.6% Pb, 13.7% Zn, 3.2% Fe, after producing 8 million tonnes at 3.9% Pb and 14.2% Zn since November 1981"

Jan 1, 1992

By John De La Vergne, Morri Medd

"This paper describes the sinking of a circular concrete ventilation shaft through 110feet of water-bearing overburden. The brine circulation freezing method was used to stabilize the walls during excavation. In order to take advantage of the cold winter weather, a custom-built heat exchanger (natural radiator) was installed in place of the standard mechanical refrigeration plant.IntroductionIn the late fall of 1979, Les Mines Selbaie awarded a contract to the firm of 1.S. Redpath Limited to sink a ventilation shaft on its property in northwestern Quebec. The shaft was to be sunk through 110 feet of water-bearing overburden and approximately 90 feet of rock to a final depth of 200 feet below surface. The water table was measured at 16 feet below the surface elevation.After examining the soils report and diamond drill core from the shaft area, Redpath came to the conclusion that freezing was the best way to stabilize the overburden for sinking. LocationThe mine site is 420 statute miles due north of Toronto, just east of the Ontario/Quebec border (Fig. 1). Access to the site is provided by a development road built by the Quebec government from the Matagami/lames Bay Highway. History of Ground Freezing In the Mining IndustryIn 1862, shortly after the development of mechanical refrigeration, a mine shaft was sunk through an artificially frozen water-bearing formation in the United Kingdom. The first application of ground freezing in North America was for a Michigan iron ore shaft in 1888. Since that time, the freezing method has been used to sink hundreds of shafts throughout the world. Its best known application was to sink sixteen shafts through the Blairmore Formation in Saskatchewan.The same method has been used in every case. It involves chilling a calcium chloride brine solution and circulating the brine in concentric pipes, spaced between 3 and 6 feet around the shaft perimeter and usually 4 to 5 feet from the limits of the proposed shaft excavation."

Jan 1, 1982

By D. F. Hambley

"In designing are passes f or underground mines specific consideration should be given to unimpaired flow of broken rock, the dump point, and typical practices f or overcoming operational difficulties. Design features such as branches, bends, and knuckles should also be considered. This paper pro vides engineering information and various criteria for designing are passes, draw points. feeders, and support systems, together with several illustrative examples.IntroductionOre passes are the primary mean s o f vertical transfer of mined ore to the ore bins and loading pocket from which the o re is hoisted to the surface (Fig. 1) . While the words "" ore"" and ""ore pass"" are used here, such transfer systems ca n be used for any broken rock.The most extensive ore pass systems are found in caving and sublevel stoping mines. Extensive ore pass systems are also found in multilevel mines having steeply dipping orebodies. In more flat-lying orebodies , ore pass systems are sometimes used in conjunction with conveyor systems .Two decades have passed since the principles of the flow of bulk solids were formulated (Jenike, 1961, 1964; Johanson and Colijn, 1964; Kvapil , 1965). However, few published papers are available that discuss the design criteria for ore pass systems. Therefore, the aim of this paper is to provide the information necessary for good o re pass design .Rock Flow in Ore Pass SystemsIf an ore pass system is to fulfill its function, the transfer o f material must occur in an orderly fashion and in such a way that the full size of the opening is employed effectively. Apart from un controlled flow at the drawpoint, or outlet , whose design will be considered later in this paper, two occurrences may impede flow in an ore pass, namely:• Hangups due to interlocking arches.• Hangups due to cohesive arches.Prevention of each of these problems will be discussed in succeeding sections of this paper. A third problem piping, is related to the ratio of the drawpoint size to the o re pass size and will be discussed under drawpoint de sign."

Jan 1, 1987

By Carlos Palacios M., Brian K. Townley

"Abstract - The mainland Aysén region of Chilean Patagonia (44°15' - 47°30'S) is a representative segment of the South American active continental margin, distinct with respect to northern and central Chile. Mineralization consists mainly of polymetallic deposits, with important Zn-Pb mines and more recently discovered Au-Ag deposits, unlike the central Andes, which are dominated by Cu mineralization. On a regional scale, rocks may be grouped in four main map units: 1) the Paleozoic metamorphic basement; 2) upper Jurassic-Cretaceous calc-alkaline volcanic and marine sedimentary rocks; 3) the Patagonian batholith, and 4) upper Cretaceous to Miocene basalts and marine and continental sedimentary rocks. The upper Jurassic-Cretaceous rocks and the Patagonian batholith formed in a volcanic arc and back-arc setting superimposed on the Paleozoic metamorphic basement.Based on geographic location and geologic and tectonic setting, ore deposits in this region are assigned to three groups, from south to north: El Faldeo, Fachinal, and El Toqui. The El Faldeo group (south of 47°05'S) includes upper Jurassic Zn-Pb skarn and associated polymetallic massive sulfide vein deposits locally overprinted by Au-rich epithermal mineralization, hosted by volcanic and sedimentary rocks and/or by rocks of the metamorphic basement. The Fachinal group (46°05' - 47°05'S) consists of volcanic-hosted lower Cretaceous Au-Ag epithermal deposits, except for the Mina Silva and Manto Rosillo deposits, which are metamorphic basement-hosted Zn-Pb skarns. The El Toqui group (44°30' - 46°05'S) comprises lower Cretaceous Au-rich Zn-Pb skarns and associated polymetallic veins, as well as Au-Ag-rich epithermal deposits, hosted by volcanic, intrusive, and marine sedimentary rocks. Galena lead isotopic signatures for each deposit group indicate a decreasingly radiogenic trend from south to north, suggesting different lead sources or differences among underlying crust. Three metallogenic provinces and two metallogenic epochs are proposed for the Aysén region: the El Faldeo metallogenic province of Late Jurassic age; and the Fachinal and El Toqui provinces of Early Cretaceous age. Résumé - La partie continentale de la région d’Aysen (Patagonie chilienne, 44°15' - 47°30'S), est unsegment représentatif de la marge continentale active d’Amérique du sud, différent des segments du nordet du centre du Chili. La minéralisation, qui consiste essentiellement en des dépôts polymétalliques, avec d’importantes mines de Pb-Zn, et des dépôts d’Au-Ag récemment découverts, différe de celle des Andes centrales où domine la minéralisation cuprifère. A l’échelle régionale, les roches peuvent être regroupées en quatre unités cartographiques principales : 1) le socle métamorphique paléozoïque, 2) les roches volcaniques calco-alcalines et les sédiments marins du Jurassique supérieur-Crétacé, 3) le batholite patagonien, et 4) les sédiments marins et continentaux ainsi que les basaltes du Crétacé supérieur-Miocène. Les roches du Jurassique supérieur-Crétacé et le batholite patagonien, formés dans un contexte d’arc volcanique et d’arrière-arc se superposent au socle métamorphique paléozoïque.Fondé sur la localisation géographique ainsi que sur le cadre tectonique et géologique, les dépôts de minerais de cette région se répartissent en trois groupes, du sud au nord, El Faldeo, Fachinal et El Toqui. Le Groupe El Faldeo (sud de 47°05'S) contient des skarns à Pb-Zn du Jurassique supérieur associés à des veines de sulfures massifs polymétalliques, localement recoupées par des minéralisations épithermales, riches en Au, et contenus dans des roches sédimentaires et volcaniques et/ou dans des roches du socle métamorphique. Le Groupe Fachinal (46°05' - 47°05'S) consiste en des dépôts épithermaux Au-Ag, se trouvant dans des roches volcaniques du Crétacé inférieur, excepté pour les dépôts de la Mine Silva et Manto Rosillo, où des skarns à Pb-Zn, se trouvent dans le socle métamorphique. Le Groupe El"

Jan 1, 1999

By James D. Bliss, David M. Sutphin

"On the basis of differences derived from genetic, descriptive, and grade-tonnage data, graphite deposits are classified here into three deposit types: disseminated flake, amorphous (microcrystalline), or graphite veins. Descriptive models have been constructed for each of these deposit types, and grade-tonnage models are constructed for disseminated flake and amorphous deposit types. Grade and tonnage data are used also to construct grade-tonnage models that assist in predicting the size and grade of undiscovered graphite deposits. The median tonnage and carbon grade of disseminated flake deposits are 240 000 tonnes and 9% carbon and for amorphous deposits, 130 000 tonnes and 40% carbon. The differences in grade between disseminated flake and amorphous deposit types are statistically significant, whereas the differences in amount of contained carbon are not .IntroductionIndustrial minerals, including mineral construction materials such as sand, gravel, and crushed stone, have historically exceeded metals in global production value. Today, industrial minerals are being used in new and sophisticated ways in response to the late 1980s emerging information- and service-based economies' requirements for less metal and more industrial minerals . Natural graphite is an example of one such mine ral that has been known since ancient times, and is now finding new applications. Graphite was first used as an industrial mineral in Bavaria in 1400 A.D. where it was an important component of crucibles. Traditionally, natural graphite has been used in heavy industries. New applications, such as development of carbon-magnesite bricks a decade ago and the current advancement of alumina/graphite refractories, are increasing its graphite use. Other new uses for natural graphite, such as the use of graphite powder as a thermal blanket for the continuous casting o f steel (Northern Miner, 1987) and the addition of expanded graphite to polyurethane foam where it acts as a flame retardant (Industrial Minerals, 1987), are increasing the demand for this mineral. To meet future demand for graphite and other industrial minerals, knowledge of the characteristics of the deposit types in which they are found is important. A further look at the deposit types for graphite and at construction of descriptive and grade-tonnage models is warranted .The graphite industry recognizes three basic types of graphite , distinguished primarily on the basis of grain size: crystalline flake, lump and chip, and amorphous. These naturally occurring forms of graphite are products of metamorphism and are found in schists of various types, gneisses, and marbles. Temperatures of at [east 400°C are thought to be required for graphite formation (Landis, 1971). Synthetic graphite, also known as artificial or manufactured graphite, is a man-made carbon product and offers higher purity and lower crystallinity than natural graphite. Several authors have written about graphite's unique physical and chemical properties and the uses for individual types of graphite (Krauss et 01., 1988; Graffin, 1983; and Harben and Bate s, 1984)."

Jan 1, 1990

By A. Jafarnia

Aluminum alloys are frequently grain refined during solidification in order to promote the formation of an equiaxed grain structure in the casting. The application of Ti-based grain refiners and/or Ti containing master alloys for improving mechanical properties may result in formation of Al-Ti based intermetallics. Although the grain refinement produces many desirable qualities in aluminum castings such as improved castability and mechanical properties, the addition of Ti to Al-Si foundry alloys may lead to the formation of some undesirable intermetallic particles such as AlTiSi and cause a number of operational problems such as nozzle blockage due to segregation and agglomeration of aluminide particles within the nozzle. There are several questions to be clarified when minor amount of Ti is added to Al-Si alloys. They include nucleation and growth of AlTiSi particles, their morphologies and orientation relationships with aluminum matrix and the dissolution of these intermetallics during the course of solidification and/or post solidification treatments. The current study was initiated to study the process and possible mechanism of aluminide dissolution and the related phenomena such as segregation and agglomeration. It reports the results found during reheating of laboratory prepared Ti-added A356 alloy at three temperature ranges of below solidus, mushy zone and above liquidus.

Jan 1, 2004

By Bill Dupley

We believe that the inability of employees to effectively manage information has reached an epidemic problem throughout the corporate world. ? All the available knowledge in the world is accelerating at a phenomenal rate. ? The whole world's codified knowledge base (all historical information in library books and electronic files) doubled every 30 years in the early 20th century. ? By the 1970s, the world's knowledge base doubled every seven years. ? Information researchers predict that by the year 2010, all the world's codified knowledge will double every 11 hours.

May 1, 2003

By James J. Roettger, Robert J. Mitchell

"The results of a series of model stope pours designed to investigate working pressures on bulkheads during hydraulic pouring of classified tailings backfill are reported. Total bulkhead pressures and fill water pressures were monitored under the condition of a fully saturated backfill. Similitude of the model testing is discussed and equations are developed to estimate bulkhead pressures under prototype conditions. The model results show that good base drainage, combined with a bulkhead setback, can reduce the expected bulkhead pressures to values such that timber or concrete block structures should be capable of supporting a saturated backfill. Introduction Bulkheads are used in underground running operations to block drift openings in order that hydraulically placed sand backfill can be contained in stope pours. Whenever possible, the sand fill is designed to have sufficient percolation rate so that excess hydraulic transport water will gravity drain out through the bulk headed drifts. This avoids costly decanting systems. Early bulkhead design assumed that the bulkhead pressure could be as high as 0h = Hy where H is the fill height and ""y is the saturated unit weight of the fill (Thomas et al., 1979)(1). A typical design pressure for a 50 m fill height would be 1250 kPa giving a design force of 12,500 kN on a bulkhead located in a drift of 10m2 in area . Typical bulkheads were 1 m thick heavily reinforced concrete structures formed and poured into a notched drift. Not only were these expensive structures but the associated problems of inside drainage systems and curing time delays increased production costs. As experience with bulkheads for large bulk pours increased and fill pressure measurements became available [see, for examples, Libby et al., 1975(2), Askey et al., 1978(3)] , 'free drainage' timber and concrete block bulkheads were designed. Substantial savings have been realized using these types of bulkheads but greater engineering design and monitoring of backfill pours is necessary to ensure that backfill pressures do not exceed the bulkhead design pressures.The effective and total stress components of fill pressure, the engineering concepts associated with the 'free drainage' design and some detailed design considerations have been discussed by Smith and Mitchell (1982)(4) . It is important to the safe use of these designs, however, that the basic engineering concepts be demonstrated and communicated to those responsible for the day-to-day backfill operations. This paper describes and explains observations from a series of model studies designed to measure bulkhead pressures in a saturated fill."

Jan 1, 1984

By K. Tsuchihashi, A. Kishimoto, T. Uda, Y. Kado, S. Maruyama

We recently proposed a continuous production process for titanium metal with some experimental results. In the process, titanium tetrachloride is reduced by Mg in the presences of Bi to form a Bi-Ti alloy at 900ºC. At this temperature, the obtained alloy is liquid and allows for the continuous removal of product and heat from the reaction vessel. The obtained Bi-Ti alloy was vacuum-distilled at 1000ºC for 24 hr, and 98 at % (92 wt %) titanium, which was easily crashed to powder, was obtained. Bi solvent was selected because of the highest titanium solubility at 900ºC and the moderate vapor pressure among the candidate metals (Bi, Sn, Pb, Zn, and Sb).

Jan 1, 2014

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

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

Jan 1, 1989

By w. w. Milde

"Since its startup in 1975, the Rabbit Lake mill has been modified (0 process both increased tonnage and higher grade ore. Ore initially came from the Rabbit Lake pit . In 1985, a major mill expansion was commissioned to allow treatment of B-zone pit ore, which is mineralogically and metallurgically different fromRabbit Lake pit ore.Mill modifications, and the changing ore characteristics and processing targets which made them necessary, are described. Mill LocationThe mill complex, shown in Figure I, comprised of milling facilities, acid plant, power generation , warehouse and administration offices, is located approximately 1.5 Ian south of the Rabbit Lake pit, and about 8 Ian southwest of the B-zone open pit mine.Original Milling CircuitOre feed to the mill commenced June 10, 1975. The mill was designed to process 1500 tonnes per day , 483 000 tonnes per year with an average grade of O.44OJo Ups and an annual production of 2000 tonnes UPs' Run-of-mine ore was dumped directly onto a 60 em square opening grizzly. Oversize was broken with an Ingersoll-Rand hydrauli c rock breaker. Minus 60 cm ore was fed to a 6 m diameter by 1.8 m long Hardinge semi-autogenous (SAG) grate discharge mill. Mill discharge was screened over a Tyler double-deck vibrating screen, with screen oversize returned to the SAG mill feed chute via conveyor belt. Screen undersize (minus 2.4 mm) was pumped to 51 cm diameter Krebs cyclones in closed circuit with the SAG mill. Cyclone overflow (about 50% minus 74 micron) was thickened to 55% solids in a 30 m diameter neutral thickener .Thickened pulp was stored in two mechanically-agitated wood stave tanks (5.5 m diameter by 6 m high), to which sulphuric acid was added to obtain a pH range of 1.5 to 2.0. The fmalleaching was carried out in five more identical tanks. Sulphuric acid and sodium chlorate were used to maintain a pH of 1.5 and a terminal emf of -450 to -500 mV. Steam sparge was utilized to obtain a temperature of 45°C."

Jan 1, 1989

By Arnaud Faucher, Amar Sabih, Sudarshan Martins, Tristan Martin, Sami Makni, Peter Radziszewski, Poorya Hosseini, Francois-Raymond Boyer

The measurement of acoustic signals produced by a tumbling mill has been previously used to determine the operating state of the mill and correlate the variations of the sound intensity with the operating conditions of the mill. Separately, the discrete element model (DEM), a software simulation of the mill, was developed to provide insight into the operation of the mill. Presently, there has not been much work reconciling the DEM simulation of the mill with the acoustic signal. Working from basic principles of linear, time-invariant systems, agreement between an acoustic DEM simulation and the measured signal is sought. First, the impulse response function of the mill is measured. The DEM provides the forces applied to the mill shell as a function of time. A convolution of these simulated shell forces and the transfer function gives the simulated acoustic signal. This signal is compared to the measured acoustic signal, both in the time domain and the frequency domain. Finally, a discussion of the results is given.

Jan 1, 2012

By W. J. D. Stone

Discussions with people knowledgeable in the insulating material field revealed that materials on the market would be considerably improved if there was a greater meeting of certain very desirable criteria. Such criteria include: (1) the material should not burn, even at higher temperatures; (2) at an elevated temperature, the material should not give off toxic gases or produce smoke; (3) the material should have a low energy input; and (4) vermin would find the material unattractive. Theoretical discussions led to the conclusion that an insulating material made by foaming a mineral, preferably of a platy nature, with an inorganic binding system that could be converted to a rigid structure at low temperature would likely meet all the above requirements. It was also theorized that the use of microwaves in the converting stage would be beneficial in the creation of a cellular structure by aiding the foamer through creating vacules of steam. Talc was selected as readily meeting the theoretical mineral requirement and the material of Baker Talc Limited was used as the basic filler. The early results obtained led to an agreement between Americ Mines Limited and Baker Talc Limited pertaining to commercial production in a specific geographic area. It was recognized that due to the economics of shipping, the availability of the basic filler material should be geographically widely spread. Samples of materials were requested and many received from all over North America and one from Britain. Enough work has been done to show that they respond to the basic process in a similar manner as the Baker Talc material. From the data acquired, it is considered that the process is applicable for the production of loose fill insulation, moulded insulation for pipes and structural steel, ceiling tile, batts, sheet and for incorporation into other products such as various roofing board materials. Sufficient development has been done to enable a budget to be prepared for the construction and operation of a loose fill insulation plant.

Jan 1, 1979

By R. A. Ford

The paper outlines: methods used for the determination of wear metals in motor and transmission oils; contaminents in motor, transmission and crusher lubricating oils; and viscosity determinations. Case histories and costs are presented to illustrate the value of an oil analysis program. Introduction NORANDA MINES LIMITED (BELL COPPER DIVISION) is located on the shores of Babine Lake, approximately 450 miles north of Vancouver, British Columbia. Access to the mine is by road from Topley, B.C., about 40 miles away. When a preventive maintenance analysis program was first considered, it was obvious that if samples were to be sent out for analysis, results would not be available for at least a week, due to the distance from any commercial laboratory. The assay laboratory was asked to investigate the possibility of determining wear metals on site. A limited program was started soon after production commenced, and this has now grown to include all large mobile equipment as well as crushers and grinding mills. The laboratory also now determines viscosity, fuel dilution, dirt and abrasives, glycol and water. All these results are ready within two days. This paper will outline the methods used, data interpretation, several case histories and the benefits from such a program.

Jan 1, 1977

By S. Malkin, Z. Shi, H. Attia, D. Chellan

An experimental investigation is reported on creep-feed grinding of a nickelbased alloy (IN718) using conventional aluminum oxide grinding wheels. Straight surface grinding expe.riments were conducted on nickel-based alloy blocks over a wide range of grinding conditions with straight oil as- grinding fluid applied at high pressure. Grinding power, forces, workpiece surface roughness, and radial wheel wear were measured. Specific material removal rate as high as 64 mm2/s was Used without burning the workpiece, which can be attributed to the extremely low specific energy of 12.6 J/mm3. It was found that the grinding wheel under the present test conditions had a strong capability of self-sharpening as indicated by the stabilized power, forces, and surface roughness after an initial short transient.

Jan 1, 2006

By B. J. Morash

"The six mineable coal seams at Quintette Coal Limited (QCL) vary in thickness from 0.75 m to 9.5 m and include waste partings varying from 0.2 m to 4 m thick. They are highly faulted and folded in some areas and dip angles range from horizontal to 90 degrees. Due to this variation in thickness and orientation of the seams, several different mining methods are used to economically recover the coal. The key to QCL's success depends on the timely collection of detailed geology data and on mine planning which allows selection of the best method of mining to achieve maximum coal recovery with minimum dilution and cost. This paper will describe the various methods of mining employed and the criteria used to select them. IntroductionThe unique challenge in mining at Quintette Coal Limited (QCL) is to extract large quantities of coal and waste, from a complex orebody, with constricted areas for mining and waste disposal. This challenge dictates the mining of as many as four 10 m benches per year, through complicated coal structures, from three separate open pits with a total of 19coal seams. This total is made up of 5 seams at Mesa, 8 seams at Wolverine and 6 seams at Shikano (Fig. 1).Computer-aided mine planning and scheduling is carried out on a routine basis to ensure the prudent selection of methods of mining, to produce plans which ensure delivery of appropriately blended raw coals to the plant, and to coordinate disposal of large quantities of waste.Several methods of mining are applied simultaneously, and as a result coal and waste are released at different rates from twelve to fifteen mining faces. In order to ensure uninterrupted flow of material from excavators and to utilize the truck fleet effectively, a computerized dispatch system is employed.GeologyGenerally, geological conditions can be related to structural (faults and dip angle) and/or stratigraphic (coal seam and interseam waste thickness) sources"

Jan 1, 1988