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By Gheorghe Marin, Franco Chiesa, David Levasseur, Bernard Duchesne

Over the past 20 years, pressure die casting has evolved to a point where structural parts can now be produced by this process. This has been made possible by the development of vacuum die casting and by the development of die-castable, low iron content alloys. This resulted in the production of low porosity, weldable die-cast parts on which heat treatment may be applied. In the present paper, the influence porosities on the tensile properties of as-cast A360 tensile test bars was evaluated. This was done by casting 24 clusters, comprising three 6mm diameter test bars each, in a 280T cold chamber pressure die casting machine after a steady dynamic equilibrium had been reached. Modeling of filling allowed to explain the differences in porosity observed in the 3 samples of a same cluster while the results of solidification modeling were related to the microstructure. Tensile samples were radiographed on a real time X-cube apparatus and separated into 2 lots: samples where no porosity defect were visible and samples with visible defects. By measuring the tensile properties of the 2 lots it was possible to quantify the drop in tensile properties brought about by porosity, which is the most common defect observed in pressure die-cast parts.

Jan 1, 2015

By P. E. Weidmark

"CANMET InformationPART 1-Published PapersAsmis, H. W., ""The dynamic response of caverns in discontinuous rock""; Proc 22nd U.S. Symposium on Rock Mechanics, Cambridge, Mass, June 1981, 272-277; 1981.Austin , M.W., Bray, J.W. and Crawford, A.M., ""A comparison of two indirect boundary element formulations incorporating planes of weakness"" ; Technical Note; Int J Rock Mech Min Sci Geomech Abstr; 19:339-344; 1982.Barrett, J. R., ""Applying geotechnical theory to underground metalliferous mining""; Proc 1st Intnl Conf on Stability in Underground Mining; Vancouver, BC, August 1982; SME of AIMMPE; 210-222; 1983.Barron, K., Wright, P.L. and Smales, T., ""Guideline s for the design of coal pillars in the No .4 seam at Mclntyre Mines Ltd ., Grande Cache, Alberta""; Proc 1st Intnl Conf on Stability in Underground Mining; Vancouver, BC, August 1982; SME of A IMMPE; 559-578; 1983.Bauer, A., ""Wall control blasting in open pit mines""; Mining Engng; 34:155-158; 1982.Bieniawski, Z.T., "" Improved design o f room-and-pillar coal mines for U.S. conditions""; Proc 1st Intnl Conf on Stability in Underground Mining; Vancouver, BC, August 1982; SME of AIMMPE; 19-51; 1982.Blackwell, G.H. and Calder, P.N., ""Practical aspects of wall stability at Brenda Mines Ltd., Peachland, BC""; 3rd Intnl Conf on Stability in Surface Mining; Vancouver, BC, June 1981; SME-A1ME; 3:573-608; 1982.Blake, W., ""Microseismic monitoring for underground stability "" ; Proc 1st Intnl Cont on Stability in Underground Mining; Vancouver , BC, August 1982; SME of AIMMPE; 272-294; 1983.Brawner, C.O., ""Stabilization of rock slopes"" ; 3rd Intnl Conf on Stability in Surface Mining; Vancouver, BC, June 1981; SME-AIME; 3:289-310; 1982.Bridges, M.C., ""Review of open stope mining in Australia""; Proc 1st lntnl Conf on Stability in Underground Mining; Vancouver, BC, August 1982; SME of AIMMPE; 813-828: 1983."

Jan 1, 1983

By Chr. Krause

Within the scope the collaborative research centre 599 (Medical University of Hanover, University of Veterinary Medicine Hanover, University of Hanover) the behaviour of the degradation of magnesium materials as implants are investigated by using animal experiments (rabbits). Thus extruded cylindrical pins from the magnesium alloys MgCa0.8%, WE43 and LAE 442 were implanted intramedullary in the tibiadiaphyses. The implantation duration was 3 and 6 month. After the explantation 3 point bending tests were carried out to investigate the possible changes of the mechanical properties. Clearly changes in dependence of the implantation duration could be determined. The three magnesium alloys show a decrease of the mechanical resistance with an increasing implantation time. To evaluate the degradation process, wich is the reason for the changes, micrographs and element analyses (EDX) have been accomplished after the 3 point bending tests. The micrographs show for all used magnesium alloys corroded surfaces but no preferred corrosion on the grain boundarys. The element analyses show beside a layer which is rich in calcium and phosphorus an agglomeration of rare earth elements in this layer. With these results a using of magnesium alloys as a material for implants can be announced.

Jan 1, 2006

By Alan Galley, Tom Hynes, Michel Plouffe

"Mining in Canada’s economy• Employs 320,000+ workers; Wages 30-60% above other sectors• Operates 220 producing mines, 33 smelters and refineries• Paid $8.4B in taxes and royalties to governments in 2010• Invests about $30B in capital projects annually • Largest private employer of Aboriginal Canadians 2• Core supplier to clean-technology sectors• Attracted 18% of world exploration spending in 2010• Efficient TSX processes - 1400 mining companies listed, ~50% of mineral projects are outside Canada• Estimated 1000 Canadian companies in 100 countries• Minerals account for 21% by value of Canada’s goods exports• Top 5 World Producer in uranium, potash, nickel, platinum, aluminum, diamonds, zinc, met coal"

Jan 1, 2012

By P. Rocque, S. Talebi

Although the measurement of blast vibration close to the blasthole is critical to the understanding of rock fragmentation mechanisms and blast damage in the rock masses, limited experience for such monitoring exists. Because much higher vibration amplitude and frequency ranges are expected in rock masses close to an explosive charge as compared to far field vibrations, different problems from those for the far field monitoring must be considered for near field blast vibration monitoring. Currently, guidelines for design of the near field blast monitoring systems do not exist. This paper describes the development of an integrated technique for vibration monitoring close to a blast hole, including selection and installation of transducers, design of a monitoring system and signal recording. A densified cement was designed for grouting accelerometers in order to match p-wave impedance between the rock and grout. The monitoring technique described has proven suitable for blast vibration monitoring within 2 m to 15 m of a blast hole having loading conditions similar to production blasts.

Jan 1, 1993

"In many gold deposits, a reasonable amount of the gold that remains in the cyanide leach tailing is associated with pyrite. Some gold plants have found it economical to incorporate gravity circuits on the cyanide leach tailing to recover the gold bearing pyrite before subjecting it to fine grinding, then recycling the ground pyrite back to the cyanide leach circuit. For low grade gold deposits the loss of gold bearing pyrite is exacerbated as the broader process economics normally favour a coarse grind (> 150 ?m). An option that has received attention over the last decade is to recover the gold bearing sulphides in the milling circuit by gravity, similar to the widely-practiced gravity recovery of free liberated gold. The modelling and simulation of a gravity gold circuit in a milling flowsheet is relatively simple compared with a gold bearing pyrite circuit, as the recycle advantages and breakage functions for gold and pyrite are quite different. This current work represents an attempt to simulate the gravity recovery of gold bearing sulphides in a milling circuit that also incorporates fine grinding, using relatively simple simulation models. The simulation results are further explored with reference to the economics of this type of circuit.INTRODUCTION It is well known that gold is associated with pyrite in most sulphide gold deposits and that the amount of gold associated with pyrite will vary from deposit to deposit. Most of the gold associated with pyrite is liberated in the grinding circuit during the processing of a gold ore. However, some gold remains occluded in the pyrite and is lost in the final leach tailings. Little information is available in the literature on methods to enhance gold liberation from pyrite by specifically removing pyrite, either in the grinding circuit or from the final tailings stream, and grinding it finer. One of the earliest record of this approach is described by King (King, 1949) where pyrite present in Witwatersrand gold ores was recovered by circular jigs and Johnson barrels followed by fine grinding of the concentrate prior to cyanide leaching. Dominy et al., 1970, provides information on the use of Yuba jigs to recover pyrite from the discharge end of ball mills. Again, the jig concentrate was ground to a fine particle size before cyanide leaching to recover the liberated gold. Unfortunately, no information is provided in these articles on the additional gold recovery from implementing these circuits in a flowsheet. Martins et al., 1993, provides details of a gravity circuit using Reichert cones and spirals to recover gold bearing pyrite from a cyanide leach tailings followed by fine grinding of the pyrite concentrate in a Tower mill. The ground concentrate returned to the front end of the already installed leach circuit. Overall recoveries were increased by some 2% to 4% depending on the amount of gold and pyrite in the plant feed."

Jan 1, 2017

By A. E. M. Warner, A. Vahed, P. J. Mackey

"Since early 2015, the price of nickel has dropped from the region of US$6/pound to current levels of around US$4.60/pound (March 2017), reflecting several market factors, but principally due to lower demand from China. Under such conditions, nickel companies have been under pressure to contain operating costs. In addition, labor and energy costs will continue to rise, while nickel ore grades will likely continue to drop. All major companies now accept the need for climate change action and consequently efforts are being made towards lowering carbon-based emissions. Nevertheless, meeting these challenges can also contribute to higher operating costs without parallel innovative developments - which at the same time, under current conditions, major companies are tending to curtail. In this paper, several productivity improvement opportunities to reduce unit operating costs at nickel sulphide and nickel laterite plants are reviewed. Opportunities include: (a) process technology and energy-type selection, production capability, optimization of process intensity and implementation of newer technologies; (b) improved productivity, equipment availability including maintenance best practice; (c) energy savings and recovery opportunities and use of energy surveys and, (d) process modeling and improved scheduling. Such improvements along with an uptick seen in nickel demand going forward should better position the world nickel industry.INTRODUCTION Nickel is an essential metal to modern society, primarily through its use as an important ingredient in stainless steel. Thus, stainless steel finds vital applications in food preparation facilities, as well as important uses in transportation and industrial applications. Canada has always played an important role in nickel production and nickel metallurgy. In the 1940s and 1950s, Canada supplied over 90% of the world’s nickel. However, this proportion has declined considerably to around 10% of the world nickel supply today. Still, Canada remains an important nickel supplier and contributor to nickel extractive technology. Due to the importance of nickel to society, nickel demand is expected to continually rise. On the other hand, nickel companies have been under pressure to contain production costs amid languishing nickel prices. While demand projections show nickel growth, there are uncertainties in actual levels of future market growth. Ore grades are dropping, while labour and energy costs, which are key cost contributors are rising, hence efforts to lower production costs will generally require innovative approaches."

Jan 1, 2017

By Leon C. Botham

?? Review of Requirements ?? Components of Modeling ?? Water Management ?? Tailings Management ?? Primarily a water management problem ?? Solids relatively easily contained ?? Process flows and runoff a continuous stream over life of mine ?? Need to allow this to safely happen over wide range of conditions

May 1, 2008

By Vincent Jourdain

Located in the James Bay Territory of Quebec (figure 1), the Clearwater property is jointly owned by SOQUEM Inc. and Eastmain Resources Inc. Exploration on the property since the early 70's has resulted in the discovery of several gold showings. Exploration work by the joint venture since 1995 has led to the definition of the Eau Claire Zone containing an indicated resource of 540 000 tonnes grading 11.1 g/t Au (8.7 g/t Au cut at 34.28 g/t Au). Hosted by the archean Eastmain Greenstone Belt, the property geology is dominated by mafic volcanics containing thin horizons of felsic volcanics and/or sedimentary rocks (figure 2). The sequence is metamorphosed to the amphibolite facies and contains two small toalitic intrusions. Regionally, the structural trend is oriented E-W but in the area of the Eau Claire Zone a second trend oriented NE-SW is also present. The first exploration work on the property was conducted by SEREM and SDBJ from 1973 to 1976. It consisted of an airborne electromagnetic survey and a ground follow-up program on several grids. This program, comprising geological mapping, geophysics and drilling, led to the discovery of the Natel showing where a drill intersection returned 8.89 g/t Au over 2.65 m. From 1978 to 1985 the area was withdrawn from staking because of the hydroelectric projects of the James Bay. In 1985, Westmin Resources Limited and Eastmain Resources began an exploration program based on a helicopterborne electromagnetic survey. Once again, a ground follow-up program was conducted on several grids. This program included a soil geochemical survey that identified a strong (up to 10 g/t) gold anomaly. Drilling of the anomaly led to the discovery of the Eau Claire Zone where resources were estimated at 270 000 tonnes grading 6.1 g/t Au at the end of 1990. In 1995, SOQUEM Inc. took an option to gain a 50% interest on the property and obtained its interest in 1998. Since 1995, two principal mineralization zones were identified on the property. The "Rosemary Zone" consists of veinlets and disseminations of pyrite and chalcopyrite within a magnetite-rich amphibolite. The mineralized zone was identified by stripping within an area of 1000 by 500 metres. Drilling indicates copper grades up to 0.32 % Cu over 49.2 m. with locally grades of 0.75 % Cu over 5.9 m. The mineralised zone is associated with QFP dykes and corresponds to a strong magnetic anomaly and a strong copper and molybdenum soil anomaly. The "Eau Claire Zone" consists principally of a set of gold bearing quartz-tourmaline veins oriented E-W and dipping at 45-50??to the south (figure 3). More than ten different veins are recognised in the zone and up to eight veins were observed in a single trench (figure 4). The host rock between the veins shows a degree of deformation similar to the regional volcanosedimentary rocks. Each vein is hosted by a unit of actinolite-tourmaline-biotite schist up to one meter thick. The veins and their hosting schist clearly cross-cut the schistosity of the hosting lithologies and the contacts between amphibolites and felsic to intermediate rocks. Usually, the veins are less than a meter thick and are composed of quartz, tourmaline and calcite. The proportion of quartz and tourmaline varies from 0 to 80% within a single vein. The veins commonly show massive, banded or brecciated texture. Sulphides, mainly pyrite, pyrrhotite and chalcopyrite, generally form less than 5% of the vein material.

May 1, 2001

By M. L. Jeremic

"The syngenetic and epigenetic mechanics of sedimentation and deformation of coal seams resulted in various types of internal structure, as listed below:TYPE I-massive structure with evenly distributed coal constituencies of integrated mechanical properties.TYPE II-broad-banded structure, with bright and dull coal bands of differential mechanical properties.TYPE III-heterogeneous structure, with sheared coal bands and partings of sectional mechanical properties.TYPE IV-contortional structure, with refolded coal layers and deteriorated mechanical properties.TYPE V-porous structure of orogenically crushed and pulverized coal, with disintegrated mechanical properties.The study suggests criteria for the estimation of coal seam internal structure (gamma-gamma density log and cracks density log), which might be related to the evaluation of strata stability and coal mineability.IntroductionIt is common knowledge that coal seams have various internal structures due to different syngenetic and epigenetic events. Investigations of the internal structure of coal seams have been carried out in the coal fields of Western Canada, as follows: geological field studies of coal-bearing strata;?,geophysical borehole surveying studies;?,geological borehole logging and crack density;?,underground phenomenological studies of mine structure;?,chemical coal analysis; and?,mechanical testing of coal samples.These investigations eliminated a large number of criteria previously established for the estimation of coal seam internal structure and indicated that, from an engineering point of view, only two of them are sufficient:(I) density of seam profile (inferred from gamma-gamma log);(2) density of crack s (inferred from geological log).On the basis of these criteria, five main structural types of coal seams have been classified, which might be related to mechanics of deformation and ' failure of mine structures."

Jan 1, 1982

By R. B. Stein

"Countercurrent decantation circuits(CCD) are often employed in hydrometallurgy to effect solids-liquid separation in combination with a barren solution wash to reduce losses of valuable solution component(s) from the tails. Bechtel Corporation uses its BEMSIM flowsheet-modelling PC computer program to simulate a CCD circuit where the ""dirty"" wash solution contains significant amounts of soluble components. An algorithm successfully models this condition and is simplified to a single expression when the wash solution is a ""clean"" solution containing no solubles. The CCD calculation module is compared to operating data from uranium and nickel-cobalt CCD circuits.IntroductionHydrometallurgical process schemes have often relied on countercurrent washing methods to reduce soluble losses of valuable product in the tails. Commonly used equipment to effect this operation is a CCD circuit of N thickeners in series, where a slurry is fed to thickener I and a wash solution to thickener N; clear pregnant solution overflows thickener I and washed tails exit as underflow from thickener N. CCD circuits of this type are typically employed when the solids tend to slime heavily and where a filter is not economic.A typical CCD circuit usually employs from two to five thickeners and can employ either a ""clean"" washing solution of, say, pure water or else the hydrometallurgical circuit may generate a ""dirty"" barren solution containing an appreciable amount of soluble component which may be advantageously returned to the process as CCD wash solution. Various authors have treated the case for clean washing solutions (Svarkovsky 1977, Merritt 1970). For the case of dirty wash solutions, an algorithm has been developed to enable efficient modelling by the BEMSIM computer program, because the need for an accurate method to calculate soluble losses is required when performing an economic trade-off analysis of the value of product lost in the tails as a function of the number of thickeners."

Jan 1, 1990

By F. Hampshire

"IntroductionThis paper is intended to cover questions raised by operating staff at various installations and is not intended to give comprehensive coverage of power plant and power system design. The paper is concerned mainly with the electrics , although a brief section gives the reasons for selection of diesels rather than other prime movers.The material is not new but brings out points which seem to be raised regularly during the design , commissioning and operation o f a new plant. Diesels versus other Prime MoversDiesel-electric plant for the mining industry falls into two major categories -emergency power and prim e power.1) Emergency power (for use only when the regular utility supply has failed) requires reliable starting and operation and reasonable first cost. Fuel economy and maintenance are of little importance as the machine(s) generate few kilowatt hours only. The diesel's competition in this field is the gas turbine, however diesels are more widely used than gas turbines in this application.2) Prime power is a different situation as the bottom line of total cost is highly affected by fuel costs.In general , mines which are within reasonable transmission distance of an existing utility find the lowest net cost result s from hooking up to the utility. If a min e is remote from an electric utility then the possible alternatives are:a) Hydro- electric power if there is a site capable of development at reasonable cost including the cost of transmission facilities. Such sites are not common, but brief and inexpensive considerationof this possibility is warranted .b) Diesel power with consideration of different grades of fuel.c) Thermal (steam) power generation from coal or oil.d) Gas turbines.In addition to the above there is the possibility of wind power (as a supplementary source) and a number of technologies which may become feasible in the future (e.g. small nuclear plants, fuel cells). For obvious reasons, small isolated generating systems required for remote mines, tend to lean to conservative technology.Among the fossil fuel plants, the diesel enjoys advantage on over-all costs as summarized in Table 1."

Jan 1, 1986

By Ben Habermann

"The object of the work described in this paper was to increase the understanding of the relation that capillary pressure of a rock, hydro-dynamics, and accumulation of oil in stratigraphie traps have to one an-other. The hydrodynamic oil-water tilt equation is derived by considering the two vector gradients involved: (1) buoyancy of oil in water and (2) hydraulic gradient.Recent theories show the necessity for oil to have a continuons phase in the reservoir rock in order to mi-grate; this fact applies to hydro-static as well as to hydrodynamic conditions. Hydrostatically, the displacement pressure of the rock deter-mines the amount of oil that can be trapped behind a permeability barrier. If the buoyancy of oil in water exceeds the displacement pressure, oil will migrate up-dip; an oil trap will be formed where displacement pressure is greater.In stratigraphie traps the pressure drop caused by moving water is positive when its direction is down-dip, helping accumulation; and it is negative when its direction is up-dip, forcing the oil into the tighter section of the reservoir. Theoretically, pro-vided we have data such as: (1) the displacement pressure of an up-dip permeability pinchout, (2) density difference between the oil and water in place, and (3) the direction and magnitude of the hydrodynamic gradient (if any), the possible extent of a stratigraphie oil accumulation down-dip can be predicted.To test the above theory sample cores from three wells in the Denver Basin were analyzed and the oil column that could be held under hydro-static conditions was calculated. After the hydrodynamic influence was considered, the results were compared with actual field data.The significant fact shown by this investigation is that the calculated oil column in one reservoir very closely approximates the actual extent of the oil column in a well. Also in accordance with the theory, the capillary pressure caused by the buoyancy of the oil column exceeded the measured displacement pressure on core samples from another productive field. For very tight shaly sand and questionable oil shows, the interpretation of data is very critical, as shown by experiments on core samples from a third field."

Jan 1, 1960

By R. J. Craig

Introduction All mining operations produce rock dust. Inhalation of rock dust, particularly if it has a high silica content, causes silicosis. Silicosis is, therefore, recognized as a hazard of the mining industry and has been made compensable throughout most of Canada. Most of the dust in any mining operation is caused by rock drilling and blasting operations and the movement and transportation of broken rock. Dust from blasting cannot be eliminated, but it can be controlled by means of increased ventilation, the use of water sprays, and the control of blasting hours. Dust from ore movement can be reduced by keeping the broken rock in a moist condition at all times. The dust from the rock drilling operation has been found to be the most difficult to control. Concentrations of dust caused by rock drills in stopes can usually be reduced to the safe minimum of 300 particles per cubic centimeter (p.p.c.c.) by diluting the air with increased ventilation. In development headings, where the machines are more confined, this is not always practicable. Therefore, the dust must be eliminated at its source. This paper deals with the reduction of dust from Leyner machines by adopting improved designs.

Jan 1, 1947

By K. C. Corin, Z. G. Song, J. G. Wiese

In the present study the effect of using different grinding media, viz, ceramic balls, forged steel balls, 15% Cr steel balls, stainless steel and mixture of stainless steel and 15% Cr steel balls (50:50) on the flotation performance of a Platinum Group Mineral (PGM) UG2 ore was investigated. Test work was conducted using a laboratory scale horizontal tumbling mill and a batch flotation cell. Power draw to achieve a specific P80 was determined for each media type. Changes in flotation behaviour were evaluated in terms of particle size distribution, water recovery, solid recovery and valuable mineral recovery. pH, Eh and DO levels were also measured. Grinding products of five different media produced similar solids and water recovery, which is indicative of the froth characteristics, but the grades and recoveries of PGE and chromite were different. The product obtained when using ceramic media showed the best flotation performance, producing the highest PGE recovery and the lowest Cr2O3 recovery. The products obtained when using stainless steel balls (SS) produced the lowest PGE recovery and highest Cr2O3 grade and recovery. The paper proposes possible reasons to explain these observations which may have significant importance for the operation of a PGM concentrator.

Jan 1, 2015

By P. R. A. Andrews, R. K. Collings

"There are more than thirty-five deposits or occurrences of celestite in Canada, chiefly in Newfoundland, Nova Scotia, New Brunswick, Ontario and British Columbia. Deposits of economic interest are the Lake Enon and MacRae deposits in the Loch Lomond district of Cape Breton Island, Nova Scotia. Two Cape Breton deposits were operated from 1969 to 1976 by Kaiser Celestite Mining Limited, which supplied an upgraded celestite concentrate to an associated strontium carbonate plant at Point Edward, near Sydney.The MacRae deposit is of current interest because of its possible development for strontium carbonate production using the ""black ash"" process. This process involves chemical leaching, rotary kiln calcining with petroleum coke, washing and treatment with carbon dioxide.Celestite is the basic material used in the manufacture of strontium chemicals, principally strontium oxide, carbonate, nitrate, chromate, chlorate, chloride, sulphide and phosphate. Strontium chemicals, in turn, are used in the manufacture of glass and ceramics, in pyrotechnic devices, in the production of strontium metal and in other metallurgical applications. Recently, strontium ferrites have been introduced into permanent ceramic magnets."

Jan 1, 1991

By Robert B. Parsons

"A joint federal/provincial/industry subcommittee of the Intergovernmental Working Group on the Mineral Industry (IOWG) has published an informative and readable report on taxation matters concerning Canada's mining industry. The report, which was presented to the federal and provincial mines ministers in September 1986, identifies and discusses key tax issues relating to this industry. The report is mandatory reading for anybody with an interest in mineral exploration or production in Canada.IntroductionIn 1986, Canada's federal and provincial mines ministers were presented with an important report concerning the taxation of this country's mining industry. This document is important for a number of reasons, two of the reasons being: first, the report contains an objective analysis of the key mineral taxation issues of the day; and, second, the report is the product of a cooperative exercise involving representatives of various facets of the industry and government. The report should be regarded as compulsory reading for anybody who has an interest in fiscal matters affecting mineral exploration and production.The ""Report on Fiscal Proposals"" was prepared by a subcommittee of the Intergovernmental Working Group on the Mineral Industry (IOWO). IOWO is a group of senior federal, provincial, and territorial government officials concerned with the analysis of mineral policy issues in Canada."

Jan 1, 1986

By R. A. Campbell

Pig iron and silicospiegeleisen were produced experimentally from a very low-grade manganiferous iron ore from Steep Rock, Ontario, by a two-stage electric smelting process. The most favourruble operating conditions were determined for each stage. Cement clinker then was made by calcining the slag from the second stage of smelting, with additional limestone and alumina. (This slag would normally be a waste material). The cement clinker produced had the composition of commercial Portland cement, and met the physical test requirements of the Canadian Standards Association Specification A5-1951 for normal Portland cement as well as could be expected for a material produced on .such a small scale.

Jan 1, 1958

By A. H. Lang

THE recent production of important quantities of high-grade muscovite at the Purdy mine, near Eau Claire, Ontario, bas brought that district into prominence and bas added another strategic mineral to the list of Canadian products. The discoveries are thirteen miles west of Mattawa and about two miles north of the Trans-Canada highway and the Canadian Pacific railway. HISTORY Clear mica of low power factor is in considerable demand in Canada and in the United States for war purposes such as radio and telephone condensers, aircraft spark-plugs, radio tubes, and transformers. Some muscovite (white mica) bas been produced in North Carolina and New Hampshire, but the United States trade bas depended largely on importations of muscovite from India and of phlogopite (amber mica) from Madagascar. For many years Canada bas been a substantial producer of phlogopite, but was unable to compete extensively in the United States with importations from abroad. Canadian production of muscovite bas been negligible as no important deposits were known. Ever since the construction of the Canadian Pacific railway, attempts have been made from time to time to mine the pegmatite dykes in and near the Eau Claire area, but, although some feldspar has been mined, no appreciable muscovite was produced. Lace in 1941, J. Purdy and H. MacDonald discovered a dyke containing large crystals of high-grade muscovite from which they are reported to have sold $700 worth of mica. They recorded claims 35974 and 35975 in December, 1941, and claim 36095 in May, 1942.

Jan 1, 1943

By H. A. Halupka, I. A. Mozer

"At its plant in San Juan, Peru, Marcona Mining Company operates two grate pelletizing furnaces for the agglomeration of 3.5 million long tons of magnetic concentrates annually. Line One, installed in 1963, was built by Lurgi as a downdraft process furnace utilizing a furnace fan for the recuperation of hot gases from the cooling zone. This line was modified in 1966 to include both updraft drying and downdraft drying, and the original roof burners were converted to side-wall burners. Line Two, a Dravo-Lurgi furnace with an annual capacity of 2.4 million long tons, was built in 1966. This line, in contrast to the modified Lurgi furnace, employs direct recuperation of hot gases from the cooling zone and utilization of process gases from the firing zone for updraft drying.At its plant in San Juan, Peru, Marcona Mining Compa-ny operates two grate pelletizing furnaces for the agglo-meration of 3.5 million long tons of magnetic concentrates annually. Line One, installed in 1963, was built by Lurgi as a downdraft process furnace utilizing a furnace fan for the recuperation of hot gases from the cooling zone. This line was modified in 1966 to include both updraft drying and downdraft drying, and the original roof burners were converted to side-wall burners. Line Two, a Dravo-Lurgi furnace with an annual capacity of 2.4 million long tons, was built in 1966. This line, in contrast to the modified Lurgi furnace, employs direct recuperation of hot gases from the cooling zone and utilization of process gases from the firing zone for updraft drying. 5 per cent increased capacity, 30 per cent lower fuel oil consumption, and approximately 400 per cent reduction in grate bar and pallet corrosion. Firing of the pellet bed was improved by conversion from roof to side-wall burners. This modification also permitted utilization of monolithic refractory in place of pre-fired shapes, thereby improving over-all furnace availability and reducing refractory stock requirements from 154 different shapes to 18.Data are presented to compare operating performance of the Dravo-Lurgi furnace and the modified Lurgi furnace. These data show 30 per cent lower fuel oil consumption and 10 per cent higher capacity per unit grate area for the Dravo-Lurgi furnace, which also averages higher availability due to greater operating flexibility."

Jan 1, 1970