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By Victor F. Hollister, Robert W. Hodder

"The petrology and mineralogy of porphyry copper deposits are thoroughly described in recent literature and cited as the definitive characteristics for this type of deposit. The magmatic-hydrothermal aspect of genesis is also dealt with in detail. However, descriptions of their internal structure and regional setting are not as rigorous, and the genesis of this structure is simply stated as the release of high fluid pressures in a cooling magma emplaced along large fault zones. Genetic relationships between internal structure, regional setting and the tectonic evolution of continents has been alluded to infrequently in the past, but can now be considered together within the developing concept of orogeny at the margins of drifting crustal plates.Tensional structures, on both local and regional scale, and a Triassic to Tertiary age are described for porphyry copper deposits. We contend that such structure and age are distinct and unifying characteristics for this type of deposit and are genetically related to major crustal movements. British Columbia has porphyry copper deposits contemporaneous with plutons 180 to 200 million years old and 40 to 60 million years old. The former age group correlates with early stages of the continent's westward drift, and the latter group with a change in tectonic style during late development of the Canadian Cordillera. Hence, one can in British Columbia reflect on the genesis of a deposit's structure in the broader context of tectonic evolution. Such consideration should lead to more definitive criteria for area selection in exploration."

Jan 1, 1972

By A. Hashempour, D. Javani

"Selection of an optimal bit is a critical issue in drilling engineering. Specific energy (SE) and Cost per Foot (CPF) are the most common methods for evaluation of bit efficiency and optimal bit selection. The major shortfall of both methods is that they do not directly account for geological and geomechanical parameters of formations being drilling. In this paper, results of using the two foregoing methods are compared using Formation Drillability (FD) method, which directly accounts for geological and geomechanical parameters of a formation. This method combines various geological and geomechanical parameters and yields a dimensionless parameter indicating the formation drilling hardness (drillability). Results of this study show that the amount of energy, cost and time spent for drilling a unit volume / length of an identical formation may vary in different wells. This is due to the fact that geological and geomechanical characteristics of a formation may vary among wells and even within short intervals of a single well. Therefore, an optimal bit may not be appropriately selected, if drilling and economical parameters are the only factors considered and the formation geological and geomechanical specifications are ignored.INTRODUCTIONMany authors such as Bilgesu, Al-Rashidi, Aminian, and Ameri (2000) and Clegg (2006) conducted research in the evaluation of bit performance and optimum bit selection. Almost all of them tried to establish a good relationship based on geomechanical parameters. Primary examples are the research done by Ubaldi (1999), Macini, Magagni, Da Dalt, and Valente (2007)."

Jan 1, 2015

By Howard J. Handewith

"Tunnel boring machines have been tried in underground mining applications as early as 1957. Although tunneling machines hardly threaten to supplant traditional drill-blast-muck operations for drifting, the latest modern machines offer substantial improvements in progress rates over traditional methods under certain conditions.An evaluation guide is offered which identifies conditions that favour machine boring. Different types of costs related to the use of a tunnel machine are discussed. The advantages of the tunnel machine over the traditional method are reviewed. IntroductionThe first tunnel boring machine ever used in a mine was in Quebec in the year 1957. Although less than successful at the time, this experiment served to illustrate the mining industry' s willingness to try new ideas. Since 1957, the manufacture of tunnel boring machines has developed into a full-size industry. Most contractors in Europe and North America will now consider the use of a tunnel boring machine first on any long tunnel that can have a circular section.The modern tunneling machine offers a great potential to the mining industry. Just as the blasthole and raise drill machines have revolutionized mining in the last decade, it is expected that tunnel boring machines will make an equal impact in the future.This is not to suggest that tunnel boring machines will replace explosives in the foreseeable future, but they can supplement drill-and-blast operations. In areas where long drifts, inclines, declines or cross-cuts are needed in a hurry, the tunnel boring machines offer the fastest way to a production return on investment. Figure 1 shows the range of production that two types of tunnel machines have produced as compared with conventional excavation methods in various ground conditions.Rotary hard-rock tunnel boring machines (Fig. 2) commonly produce progress rates in excess of 20 metres per day in uniform ground from 300 to over 2,000 kgl cm2 in unconfined compression strength . These averages are for the completed tunnels. One 7. I6-metre-diameter tunnel boring machine just completed a 1O.7-km tunnel in hard rock of 700 to 2,800 kg/cm>, The last eight months of production averaged 30 metres per day."

Jan 1, 1980

By E. W. Vekris

Patents are playing an increasingly important role in the business world. A diverse patent portfolio can enable a company to secure a monopoly within the market, which can provide a competitive advantage over competitors. At the same time, possessing a diverse patent portfolio greatly increases the value of a company's intangible assets. This paper provides an overview of the patenting process as it pertains to the fields of metallurgy and mining, and summarizes some general patenting strategies. A review of new "green technology" initiatives recently adopted by Patent Offices around the world is also provided.

Jan 1, 2011

By F. Sorenson, P. A. Castellarini, F. Garbarino, M. N. Garcia

"Recently, significant efforts to improve productivity from the tight intervals of the Mulichinco Formation within the Sierra Chata Field in the Neuquén Basin have been ongoing. Because conventional high quality reservoirs were being developed in this field, a proper reservoir understanding and completion approach was applied. After developing these high permeability reservoirs, the operator began evaluating the tight intervals and new areas within the field, but a completely different approach was necessary to achieve motivating production improvement.An extensive study to help enhance reservoir understanding and identify key factors controlling productivity of these tight intervals (which tend to be in the range of 5 µD) has been ongoing. Some of the issues discussed in this study are 1) petrophysical review, 2) rock properties calibration, 3) geomechanics understanding, 4) faulting and micro faulting/lineaments description, 5) stimulation and completions review and, 6) understanding key production drivers.As in many other tight reservoir projects, a considerable area of the reservoir must be effectively stimulated during the hydraulic fracturing process to achieve economic productivity. Two critical issues hinder these objectives. First, the low permeability in addition to a pore pressure close to or even lower than hydrostatic are critical characteristics when attempting to flow back the well and clean up fractures. Second, very high horizontal stress anisotropy resulting from a strike slip stress regime promotes the generation of simple planar bi-wing fractures. It is well-known that this fracture geometry will contact much less reservoir area compared to more complex fractures, as the operator would normally intend to create at very low permeability reservoirs.This paper discusses these issues and how they were addressed. A pilot drilling and completion program was initiated during 2012 to validate this study. Key factors include well location relative to formation unconformities, their orientation relative to the far field principal stresses, hydraulic fractures generated, and overall completion design."

Jan 1, 2015

By Alan Rice

Abstract-The mechanism by which stratiform ore deposits of PGE (platinum-group elements) are laid down in ultramafic igneous complexes is not completely clear. Early studies by the author and coworkers on numerical analyses of the convective cooling of low-Rayleigh-number magma chambers examined the effect of suspended crystal load on fluid density, and raised the possibility that the growth of the suspended crystal load during cooling could split a magma chamber into several convecting layers. The lower layers would have a higher content of refractory phases than the upper layers, which would consist of more evolved melt. This paper considers numerical modelling, as well as theoretical and experimental work in other fields dealing with suspended loads in fluids. The calculations, which are based on the physics of convecting magmas, yield quantitative relationships consistent with the observation that economically interesting stratiform PGE deposits are restricted to large magma bodies, and also yield estimation of the depth in a magma chamber at which certain grades of mineralization may occur.

Jan 1, 1997

By Alan Rice

The mechanism by which stratiform ore deposits of PGE (platinum-group elements) are laid down in ultrama?c igneous complexes is not completely clear. Early studies by the author and coworkers on numerical analyses of the convective cooling of low-Rayleigh-number magma chambers examined the effect of suspended crystal load on ?uid density, and raised the possibility that the growth of the suspended crystal load during cooling could split a magma chamber into several convecting layers. The lower layers would have a higher content of refractory phases than the upper layers, which would consist of more evolved melt. This paper considers numerical modelling, as well as theoretical and experimental work in other ?elds dealing with suspended loads in ?uids. The calculations, which are based on the physics of convecting magmas, yield quantitative relationships consistent with the observation that economically interesting stratiform PGE deposits are restricted to large magma bodies, and also yield estimation of the depth in a magma chamber at which certain grades of mineralization may occur.

Jan 1, 1997

By J. E. Ryan

General Description Due to the extreme cold weather experienced in Flin Flon during the winter months, thought and precaution were necessary in the design of the plant buildings. The machine shop, carpenter shop, drill shop, and coal plant buildings are similar in the building materials used in their construction. They are sided with two-inch shiplap, insulated with celotex and asbestos paper, and covered with corrugated iron on all side-walls. Roofing consists of 2 by 4 lumber on edge, laminated, and further covered by celotex and three-ply roofing. These buildings are heated by means of unit heaters. The heaters are primarily steam-heated radiators, through which the air of the buildings is circulated by electrically-driven fans. Our machine shop is located to the east of, but central to, the main operating buildings of the mine and plant, and is so connected by a net work of tracks as to be able to serve all portions of the entire plant conveniently. The building is divided into two bays, the main bay 53 ft. by 340 ft., and the east bay 24 ft. by 340 ft. The shop office and drafting room, a two-story annex 24 ft. by 30 ft., is located on the west side of the shop. The arrangement within the shop is such as to house conveniently the several departments, namely, heavy machine tool section, repair floor section, boiler shop heavy tool and floor section, blacksmith heavy tool and forge section, tool room, electric welding rooms, stock room, tin and copper shop, and electrical parts and armature winding and repair shop (see Figure 1). All the heavy tools, the repair floor section, and railway tracks are so located in the large open bay as to be fully serviced by an electrically operated 15-ton bridge crane, with a span of 50 feet and a travel the full length of the shop. A standard-gauge railway track, branched off the main line, penetrates the full depth of the building. This track lies along the extreme east side of the main bay, allowing easy entrance and movement of rolling stock and heavy machinery, loaded on standard flat-cars, to the repair floors in the main bay. Eight jib cranes, affixed to building columns, further facilitate the heavy repair work throughout the various shop divisions. Our light and heavy machine tools are standard equipment, not unlike tools used in mine, mill, and railway shops.

Jan 1, 1935

By Stanley Davidson

"The ore deposit mined by Falconbridge Nickel Mines, Limited, is one of the numerous nickel-copper sulphide bodies marginal to the large oystershaped mass of differentiated norite in the Sudbury district, famous as the world's most important nickel producing field. The unique character of the ore deposits of the district has resulted in its intensive geological study over a period of more than 50 years. The results of these studies have given rise to a voluminous geological literature and to a great deal of controversy as to the genesis of the ores. This description of the structural geology at the Falconbridge mine is presented in the hope that it may form a small part of the chain of evidence leading to a reasonably satisfactory explanation of the ore genesis.The mine, named after Falconbridge township in which the deposit occurs, lies along the southeast margin of the norite mass, which, however, is h::re concealed beneath a deep mantle of glacial sands and gravels averaging over 100 feet in thickness. As a consequence, the deposit was not discovered by the early prospectors, and it was not until 1916-17 that E. J. Longyear, of Minneapolis, located the ore by drilling(ll). The discovery was foreshadowed in 1899 by the work of Thomas A. Edison, who found indications of the deposit by what is believed to have been a combination of magnetic and electrical geophysical surveys. He sank a prospect shaft over what has to date proved to be the largest and richest ore section in the mine. A wet quicksand layer at the rock surface proved impenetrable, however, and the 'Edison' shaft never reached bed-rock.The Falconbridge property was acquired by the Lindsley interests in 1928, and ore output, since its inception in 1929, has gradually risen from a modest beginning to the present 2,000 tons and more daily. Total production in this period is 7,500,000 tons of ore averaging 1.72 per cent nickel and 0.89 per cent copper, together with a small but valuable content of precious metals, principally of the platinum group."

Jan 1, 1954

By Justin S. Johnsen

As OEM sensors and interfaces have grown in number, the available data from equipment in the mining environment has continued to multiply. This equates to an increased visibility of operating performance, mechanical and electrical health, and predictive monitoring that can directly improve maintenance reliability and scheduling. With increased visibility, where should a reliability engineer begin to look to directly impact Capacity Assurance? More specifically, what source will provide inputs to the Failure Modes Effects Analysis (FMEA)? Results from these analyses must be documented, and they must contribute to the overall mission of the mining company; these results must reduce costs and increase profits. Through detailed data capturing, documenting, and analysis, Modular Mining Systems? Time Tracking application, used in the MineCare® maintenance management solution, can drive decisions and provide direct impact to engineering projects for continuous improvement in the mine maintenance organization.

Nov 1, 2011

By Linda C. M. Elliot, Liangxue Liu

"The deposition of tailings under water is considered to be one of the most environmentally promising and potentially cost effective methods to reduce or eliminate acid mine drainage from tailings. One of the concerns of subaqueous deposition has been that metals may leach into the cover waters, thereby increasing aqueous metal concentrations to higher than acceptable limits. This potential was seen to have an even greater possibility for impact when the tailings are deposited under acidic lake water.The following paper summarizes the results of subaqueous tailings pilot column test work conducted to determine the effects of subaqueously deposited tailings on lake water and tailings pore water. Two types of tailings were tested: high sulphide tailings (pyrrhotite concentrate), and low sulphide tailings (end of pipe slime tailings).Data was collected from five columns over a 13 month test period. The results indicated that a stagnant I 000 mm water cover was capable of maintaining the underlying tailings in a reducing condition. The upwards diffusion of pore water resulted in a pH increase in the waters overlying the thickened pyrrhotite tailings and the pyrrhotite tailings with a shallow cover of substrate. A conductivity gradient between the tailings and the water cover caused a diffusion of salts upwards into the overlying water column. Precipitation noted at the tailings water interface may be related to the precipitation of ferric oxyhydroxides, which resulted in a decrease in Fe concentrations noted in the water cover. Other metal concentrations did not exhibit significant increases in the water cover. A sulphate concentration gradient between the tailings and the water cover may have caused the diffusion of SQ4 from the tailings into the water cover."

Jan 1, 1997

By Minoru Fujita, Ian M. Johnson

"A helicopter-borne geophysical survey was flown in 1978 over selected areas on Kyushu Island, Japan. The principal sensors were a moving source electro-magnetic system and a magnetometer. Maps of apparent resistivity were generated from the EM data. Based on the resistivity signature of known deposits within the survey areas, targets were selected for ground follow-up. Drilling of one such target in late 1980 resulted in the discovery of a gold deposit from which full production will begin in the summer of 1985. The deposit contains a minimum 120 tonnes (3.86 million ounces) of recoverable gold and is the largest in Japanese history. The deposit is in a geological setting previously unsuspected of hosting precious metal deposits. The case history suggests a preferred exploration strategy which might be employed in other similar geological environments.IntroductionThe Hishikari area is located some forty-five kilometres north of Kagoshima city, Kagoshima Prefecture, Kyushu Island, Japan (Fig. I). The area and its environs is one with a number of gold deposits which have been worked with varying results since the late 1800s. The large st deposit in terms of recovered gold is the Ohkuchi (or Oguchi) Mine (Fig . 2) which was recently closed due to exhaustion of reserves. The Ohkuchi Mine started production in 1896. A total of 22.2 tonnes (714 ,000 ounces) of gold, with an average ore grade of 13.6 grams/tonne (0.39 ounces/ton), was extracted over the Life of the mine.In an attempt to discover new deposits , the Metal Mining Agency of Japan (MMAJ) carried out a regional geologic mapping program of the area between 1975 and 1977. This was followed by a helicopter-borne electromagnetic and magnetic survey. The airborne survey was flown by Scintrex and the compiled results presented to MMAJ in early 1979."

Jan 1, 1985

By L. Lamothe, C. H. The

"Pilot precipitator tests were conducted at Noranda's Horne Smelter in late 1978 to evaluate methods of improving converter dust collection efficiency. A bout 35 Nms/min. of converter off-gas were isokineticatly diverted from the converter flue to the pilot precipitator leased from Flakt (Canada) Ltd., consisting of three fields, one transformer-rectifier set per field and 77-m2 total collecting plate area. The effects of gas volume flow rate and conditioning the gas with sulphur trioxide and/or additional moisture were tested. II was found that gas flow rate and moisture level had the most pronounced effect on collection efficiency. Based on a techno-economic assessment of different options for improving converter Courell efficiency, waffle hoods and water sprays were installed on the converters to reduce air infiltration and increase the moisture level in the gas.BackgroundThe Horne Smelter of Noranda Inc. is situated in northwestern Quebec and, since the closure o f the min e in 1976, has been operating as a custom smelter. The concentrates treated at the smelter come from various mines with mixed sulphide ores , many o f them containing significant amounts of lead and zinc which makes dust collection in electrostatic precipitators mo re difficult than normal.As part of a continuing program on reducing smelter dust emissions, the No . 6 Cottrell was installed in 1972 up stream of Nos. 2 and 4 Cottrells (in parallel) in a n attempt to improve dust collection by increasing the over- all precipitator capacity ( Fig. I). However, it has never per formed a t its designed efficiency o f 94%. The average efficiency established in various test s was in the range of 60 – 65%."

Jan 1, 1985

By J. Kronsteiner, E. Kabliman

"In the present work, we developed a Smart Process Control Toolkit (SProC) as a single simulation environment for the modelling of materials microstructure and its interaction with the local microchemistry during manufacturing of semi-finished products. This toolkit supports the data communication between sub-sequent processing steps such as casting, homogenization, pre-heating to deformation, etc. The thermo-kinetical simulation software MatCalc of MatCalc Engineering© GmbH was used for modelling of precipitation kinetics, such as formation of primary and secondary phases and their evolution. An import/export functionality of the precipitation distribution after each processing step was implemented to follow the parameter history. For the evolution of the local microstructure, a Mean Dislocation Density based Model (MD2M) was used. This model consists of two parts: (1) Flow Stress Model for calculation of the total strength during the deformation and (2) Static Recrystallization Model for account of the recrystallization and grain growth after the deformation. Validation was done by a comparison of experimental and simulated hot compression tests of a conventional AA2024 alloy.INTRODUCTION Optimization of a semi-finished products quality, elimination of typical production issues and cost savings are of a great demand for supply industries. However, it is currently not feasible to investigate the whole manufacturing process in detail at an industrial level. Concerning the processing parameters, one must understand the correlation mechanisms between macroscopic properties and microscopic material behavior. Numerical simulations, which could reproduce the real processing conditions on the one hand, and employ a physically based modelling on the other, are thus attracting a lot of attention and their power is no longer under the question. It is well known that e.g. the total strength of the material depends directly on distribution of precipitation particles and mean grain size. In order to follow their evolution during the manufacturing process beginning from casting to the final semi-finished product, and thus be able to control the process, one should use the techniques which would at the same time reproduce experimental processing conditions of real size objects (e.g. sheet, extrusions, etc.) and account for the evolution of a local microstructure and its interaction with the microchemistry. A commonly used approach is to implement a model which would describe the evolution of microstructure based on a dislocation density approach into a user defined material subroutine of some finite element solver. There is, however, also an influence of the manufacturing process by e.g. the evolution of a local microchemistry (formation, transformation and dissolution of the precipitation particles) on the microstructure and thus the macroscopic material behavior. Thus, a method is needed to follow the variable history through the simulation of the whole production chain."

Jan 1, 2018

By T. Sugawara, H. Sekimoto

Electrorefining of low-grade copper alloys containing various amounts of nickel, lead, antimony, bismuth, arsenic, selenium, silver, and gold in sulfamic acid media was demonstrated. The copper concentration of the alloys used as an anode was 70–90 wt%. The electrolyte contained 100 g L-1 of free sulfamic acid and 40 g L-1 of cupric ion. Galvanostatic electrolysis was conducted at 200–300 A m-2 in the electrolyte using a low-grade copper alloy anode and a stainless steel cathode at 25C. The terminal voltage was approximately 0.8 V at the start of the electrolysis, although it increased periodically to approximately 2.0 V and then shortly returned to its initial value. Nickel, lead, and arsenic from the anode dissolved in the electrolyte and were removed. Antimony, bismuth, selenium, and silver were removed as solids. Consequently, a dense copper cathode was obtained, and the concentration of copper was evaluated by inductively coupled plasma – optical emission spectrometry to be 99.82–99.99 wt%. INTRODUCTION Electrorefining of copper is conventionally carried out in a sulfuric acid electrolyte using crude copper assaying at 99.5 wt% Cu as the anode (Biswas & Davenport, 1994). Elements more noble than copper do not react anodically, and consequently, they are distributed in anode slimes. Elements less noble than copper dissolve from the anode. Nickel and arsenic are stabilized as aqueous species. Lead, antimony, and bismuth react with water, sulfuric acid, or arsenic acid to form barely soluble compounds; thus, they are distributed in anode slimes. An emerging issue in the electrolytic refining of copper is an increase of impurities in crude copper used as the anode (Moats et al., 2013). This is due to an increase in the content of impurities in copper concentrates as well as an increase in the types of secondary copper feedstocks (e.g., E-Scraps, automotive shredder residues, and smelting residues) treated in the copper pyrometallurgical process. An extreme case is a copper smelter that does not use copper concentrates as feedstocks. In such a process, copper-bearing feedstocks are smelted in a top submerged lance furnace to prepare low-grade copper alloys assaying at 80– 90 wt% Cu (Sekimoto et al., 2013). Such low-grade copper is not acceptable as an anode in the conventional copper electrolytic refining process because it is easily passivated during electrolysis. Consequently, electrolytic copper is produced by leaching the atomized low-grade copper in a sulfuric acid solution with oxygen, followed by electrowinning. However, electrowinning should be avoided whenever possible because the electrical energy consumed in electrowinning is 5–10 times higher than that consumed in electrorefining. Therefore, the development of technologies for electrorefining of low-grade copper alloys is desirabl.

Jan 1, 2019

By A. M. Salomon de Friedberg

With respect to impurities, HBM&S' copper smelter, located in Flin Flon, Manitoba, is in an unusual position. In addition to the usual concerns, the fact that copper and zinc production at Flin Flon is closely integrated results in the unique situation where feed to the copper smelter typically contains 7% to 8% zinc. This paper discusses the ramifications to copper smelter operations resulting from the marriage of HBM&S' metallurgical plants. Distributions of impurities (specifically Zn, Pb, Ni, As, Bi, Sb, and Cd) are presented and operating practices designed to reduce the impact of impurities on anode copper quality are detailed.

Jun 1, 1993

By C. R. Whittemore

IT can be truly stated that no branch of the engineering industry has progressed more rapidly in the last few years than that of welding. In spite of depressed economic conditions, this industry has continued to advance along scientific lines, replacing the old hit-and-miss method of welding. The development work is intensive, and increased activity is recorded in every sphere of the industry, new applications of existing methods, together with new processes, being added to those already proved in practice. The general acceptance of the welding processes can be measured by their utilization as a manufacturing tool in the metal-working industries. Many manufacturers have partially or wholly adopted welding. These concerns have on their staffs welding specialists, design engineers, and metallurgists, who are qualified to design and supervise the manufacture of welded parts, at a considerable saving to the purchaser. The steady, consistent, and sound growth of welding is based upon investigation of the fundamentals of the various processes, together with their proper application. The classification of welding processes varies in different countries. In Europe, they are divided into two main classes, namely, heterogenous and autogenous. In the former, the parts are joined, as a ruler without melting the edges, and by using as filler a metal different from that of the object welded. Such welding differs from soldering and brazing in that higher temperatures are required to effect the union of the parts. In autogenous welding, the parts are joined by melting of the edges, with or without the addition of a material similar to the parts being joined.

Jan 1, 1936

By P. J. Williams, A. R. Foster

Petrographic studies, assay records, and laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS) analyses of major sulfides suggest nearly all of the gold at the Ernest Henry Cu-Au deposit occurs in the form of native gold or electrum (95-65 wt.% Au); sylvanite and dissolved gold in cobaltite, chalcopyrite, and pyrite make only minor contributions. LA-ICP-MS analyses of the gold contents of chalcopyrite gave from 8 to 139 ppb (mean = 56 ppb), more than an order of magnitude lower than those experimentally determined in chalcopyrite in equilibrium with native gold at the estimated mineralization temperatures (350°-450°C). Gold content is more variable in pyrite (1-400 ppb, mean = 77 ppb) and highest in narrow growth zones of a subordinate type of complexly zoned pyrite wherein it is associated with elevated As, Ag, Sn, Sb, Te, and Bi. Deposition of gold-electrum was closely associated with, but preceded some of the chalcopyrite deposition, as indicated by microtextures and lower bulk Au:Cu ratios in late-stage chalcopyrite-rich veins. Gold grains have maximum dimensions from <1 to 50 micrometers, and are heterogeneously distributed with most occurring in microscale clusters. Fifty-five out of 76 grains recorded in polished sections are in contact with both chalcopyrite and pyrite, and many of the rest are in sites where such a relationship could exist in the third dimension. The dominant textural sites are intergrowths with chalcopyrite in microveinlets cutting pyrite, and on faces of pyrite grains in contact with chalcopyrite. Scanning electron microscopy, electron microprobe analysis, and proton induced X-ray emission studies show that pyrite associated with gold includes complexly zoned, weakly zoned, arsenian, and arsenic-poor types. The textures are compatible with the possibility that most gold was deposited electrochemically as native metal on pyrite surfaces. The textural distribution of gold has important metallurgical implications given that the ore processing circuits at Ernest Henry and most other sulfide copper mines are designed to exclude pyrite (and arsenic) from concentrates.

Jan 1, 2007

By F. Ajersch, A. R. Hekmat

Apparent viscosities of hypo-eutectic (Al-7% Al) and hyper-eutectic (Al-35% Si) binary alloys were measured in the semi-solid state using a Couette type viscometer at variable shear rates. Analysis of the microstructural evolution demonstrates the differences in the rate and degree of attrition of the primary phase particles which are characteristic of the thixotropic nature of the semi-solid alloy. It was observed that the Si primary phase in the hyper-eutectic alloy is much more difficult to fragment than the dendritic a-Al phase in the hypo-eutectic alloy. For the case of the a-Al, the dendritic structure is broken down by attrition and fracture of the dendrite arms whereas the fracture of the Si hexagonal crystals in the hypereutectic alloy occurs along the {100} and {110} cleavage planes. Results are presented for fixed solid fractions of the primary phase at isotherm condition for each type of alloy.

Jan 1, 2006

By R. P. Nicholson

On September 3rd, 1947, the Acadia Coal Company put into operation a central coal preparation plant. This plant was designed to process all coals mined by this Company in the Pictou County coal field. The problem, briefly, was to make a three-way separation of the raw coal fed into the plant. It was desired to remove all stone, metal, and wood from the marketable coal and to produce a splint coal from the raw material which would be suitable for making power. This splint coal product is belted directly to the power plant which is adjacent to the wash plant. To attain this object it was therefore necessary, first, to wash the raw coal, removing all splint, stone, metal, and wood. The stone, metal, wood, and highest-ash splint had then to be removed by a second washing in order to obtain the lower-ash splint for use in the power plant. The plant is on the east side of the Allan colliery, in the town of Stellarton (see accompanying photograph). It is of steel frame construction with wood siding, covered on the exterior with corrugated galvanized iron. Considerable concrete had to be poured for the foundation piers as the plant site is largely &apos;fill&apos; ground. This necessitated the construction of extremely heavy footings containing a large amount of reinforcing steel. In all, 884 cu. yds. of concrete were poured for the various pits, tanks, and foundations; its average test was about 3,500 lb. per square inch. At the time the plant was constructed, the steel shortage in Canada and the United States was acute and, in order to obtain steel for the structure which is four stories high- an unused part of the Allan bankhead was torn down. Enough steel was obtained from this demolition to fabricate the new plant.

Jan 1, 1948