Search Documents

By Melvin S. Taylor

The environmental control program at Cassiar Mine is an active one involving government, unions and company personnel all working together to achieve a goal- "A clean and safe working environment". This can only be achieved by utilizing three of Cassiar's most important resources; i.e., people, time and money. Past environmental programs have more than proved that the goal can be reached and. with the future programs now in progress. Cassiar Asbestos will achieve its environmental goals.

Jan 1, 1978

According to the principle of similarity, the physical and chemical configurations of a system can be defined by ratios of magnitudes within the system and do not de-pend on the size or nature of units of measurement. In the present work, the similarity principle was utilized in evaluating the reducibility of various iron ores in a rotary batch furnace under optimum operating conditions. It was then used successfully to extrapolate the results, first to the operation of a 20-ft. pilot-plant kiln and then to an industrial-size 80-ft. kiln. By means of this systematic analysis of kiln operation, it was possible to increase the production capacity of the kiln considerably. T HE kilns used by the Strategic-Udy process for the partial reduction of iron ores are, in most aspects, similar to conventional calcining kilns. Iron ore is fed continuously in the upper (feed) end of the kiln and, as the latter rotates

Jan 1, 1964

By Horace Freeman

"IN THE writer's opinion, the most important industrial re-search problems in Canada concern development of technology for the treatment and commercial utilization of the recent discoveries of v.ast quantities of easily concentrated iron ores in both eastern and western Canada. They exist in both magnetite and hematite forms. The subject is doubly important because of the lack of metallurgical coking coal in Canada. Methods for utilizing our lower grade eastern and western coals for reduction purposes must be developed. We are fortunate in our supplies of oil and gas, which can supply the heat requirements for processing or for thermal electric plants, which are now competitive with hydro-electric plants in the industrial areas. These are among the reasons which have prompted the writer to continue the development of the co-current rotary kiln direct-reduction process outlined •in his report to this Institute at the 1956 Annual Meeting ( 1) in the face of the scepticism which has surrounded the numerous costly failures in 'sponge' or 'direct' iron production. The work involved in bringing the concentrating ores of Canada to the metallic state involves, firstly, concentration of the ores; secondly, preparing the concentrates for reduction; thirdly, reduction of the 'reconstructed' ore; and finally the steel making process. These briefly will be dealt with in order, giving emphasis to the most important of these steps, the reduction process which is the main subject of this paper."

Jan 1, 1959

By H. Tetu, F. Pells

"The copper-molybdenum property of Brenda Mines Limited is located in the Okanagan district of British Columbia, approximately 25 miles west of Kelowna. The Okanagan Valley is a resort and fruit-growing area, and therefore pollution control measures are more stringent than in some remote areas.The Brenda plant began production in April 1970 and is operated at a rate of 24,000 tons per day. The plant site is located at an elevation of 4,800 feet, which is approximately 3,600 feet above the level of Okanagan Lake. The site is in the Okanagan drainage basin.The major consideration in the design of the system was the prohibition of any downstream discharge. It was therefore necessary to redaim as much water as possible and to minimize the addition of fresh water to the system. The maintenance of a water balance is of critical importance.This paper will outline the major design criteria for the systems and the site investigations which were carried out. The design and construction of the facilities will be de-scribed and current operating experience will be outlined."

Jan 1, 1971

By Paul W. Richardson

"Introduction And AcknowledgmentsTHIS PAPER outlines the geology and discusses the geological problems of the Mindamar mine. It is impossible to acknowledge the contributions of ideas of all the geologists who have worked in the area. Among the more important contributors are K. DeP. Watson, W. S. James, B.S.W. Buffam, and L. J. Weeks, and John MacPherson, the resident geologist at the mine.A mineralogical and chemical study of the ore and country rock is being carried •on by Dr. Watson at the University of California, Los Angeles.General InformationThe Mindamar mine is on Cape Breton Island, forty miles south-west of Sydney (Figure 1). The nearest railway stations are at St. Peters, which is thirty-two miles southwest of the mine, and at Sydney. Good gravel-surfaced roads connect the mine to the railways.The mine is producing at the rate of 600 tons a day of ore containing zinc, lead, copper, and minor amounts of silver and gold. At the present time the mill feed averages 9 .per cent combined metals, of which zinc makes u:p 7 1per cent and lead and copper each 1 per cent.General GeologyThe ore being mined ,by Mindamar occurs in a shear zone parallel to a northeasterly striking, vertically dipping, series of rocks consisting of rhyolite tuff, rhyolite, minor more basic flow rocks, and diorite (Figure 2). In the vicinity of the mine, these rocks have been termed the Mine Series. They belong to the Bourinot group, which has been assigned by L. J. Weeks to the Middle Cambrian. At the latitude of the mine, the Bourinot group is bounded on the northwest by the Stirling fault and extends eastward for two miles."

Jan 1, 1953

By M. Tardif, F. L. -Lavoie, M. Ruel

"In mineral processing, it is often very difficult to reliably measure several key operation variables. The harsh environment and high temperature encountered in pyrometallurgy processes lead to some difficulties when selecting the instruments, valves and actuators. If an important variable cannot be measured or manipulated adequately, controlling it can really become a big challenge. Sometimes, it is simply impossible to find the perfect equipment for the task. To help overcome these difficulties, a different approach is required. This approach will not correct the inherent problems related to the instruments and valves, but will cope with these problems. This article will demonstrate how modern process control techniques can be used to solve complex problems while remaining easy to implement. In this article we will described how soft sensors and multivariable fuzzy logic control were implemented at Koniambo Nickel to stabilize the furnace feed and allow for safe and reliable operation of an 80 MW DC arc furnace.INTRODUCTION Process Overview The process plant at Koniambo Nickel SAS is located in the North Province of New Caledonia, 310 km north of Noumea. The nickel-bearing ore is mined in the nearby Koniambo massif. After being screened and crushed, the ore is transported to the processing plant using a 12 km conveyor. After stacking in two blending piles, the ore, containing 2.3% nickel, is fed to the processing plant where it will go through the NST process (Nickel Smelting Technology) before being sent to refining and shotting. This article will focus on the improvement to control of the NST processes. The first steps of this process consist of milling the ore and removing all moisture through calcining (Figure 1)."

Jan 1, 2017

By A. R. Khodabandeh, T. Nematkhah

Correct selection of forging parameters is very important to produce sound superalloy parts. In this investigation nickel-iron base superalloy IN901 successfully forged and seal spacer, which is a part of airplane with about 11 kg weight has been produced. Forging has been performed on the basis of hot compression results, which show deformation above 1100°C associated with dynamic recrystallization (DRX) which can increase the workability of material. On the other hand annealing at 1100°C decreases the flow stress during hot compression, and then increases the material formability. Then billets annealed at 1100°C in electrical furnace for 24 hours and reheated again to 1100°C before forging. Initial square cross section billet with 128mm side and 202mm length forged immediately after reheating by 80MN mechanical press. Specimens forged in five steps: upsetting, three steps molding and finishing. Preformed and molded specimens reheated in electrical furnace before later step of forming. Finally specimens trimmed by 1 OMn mechanical press and hot set by hydraulic press and then cooled in air to room temperature. Results show that reheating temperatures has been selected correctly because there isn't any surface crack and die cavities filled completely by forging material. Material flow has been carried out properly and there isn't any defect in critical points especially in extradoses and intradoses. Microstructural examinations show that grain boundaries contain Ti-rich globular particles that formed during cooling.

Jan 1, 2006

By G. F. Round

In order to obtain values of angle of shearing resistance and initial resistance for McMurray oil sand for use in general design calculations, the shear strength of this oil sand was measured in a controlled strain type tester, modified so that the rate of deformation could be varied between 0.01725 and 0.1869 inches per minute. Effect of temperature was investigated by adapting the equipment to operate at both 71 ° and 185 °F. The data are reported in terms of angle of shearing resistance and initial resistance for varying rates of deformation, composition and temperature. While the main sets of results reported here were obtained at a bulk density range of 108.7- 109.5 lb. / cu. ft., some results were obtained at a bulk density range of 101-102 lb. / cu. ft. Analysis of varance tables have been drawn up from the results obtained from least squares correlations and significance tests applied. It was concluded that oil content and temperature were significant variables for the degree of shear strength developed by the oil sand; increase of oil content and decrease of temperature each cause an increase in shear strength. The bulk density range 108.7 to 109.5 lb./cu. ft. gave angles of shearing resistance from 30° to 40° and initial resistance values of 0.37 p.s.i. to 0.85 p.s.i. For the bulk density range 101 to 102 lb. / cu. ft., lower values of shear strength were obtained, indicating that compaction density was also of importance

Jan 1, 1960

By I. Caraconcea, M. Cousineau, S. Gariepy

"Several base metal plants operate in low grade/high tonnage conditions which impose strict cost control on all fronts for their operations to remain profitable. This leads to decisions regarding plant design, procurement, operations and maintenance that often favor cost minimization over value optimization. This may hinder the representativeness of the metal accounting systems while this should be a priority in a low margin environment. Such poor representativeness not only creates confusion in plant scheduling but can also hide suboptimal metallurgical performance. Furthermore, this situation can run undetected for a while since one dominant feature of a poor metal accounting system is its poor self-awareness. During their practice, authors have particularly identified measurement bias and reproducibility, as well as their impact on metal recoveries as areas of concern. These issues have not been extensively reviewed in the specific context of precious metals in base metal plants. Pragmatic solutions are proposed either at the design stage for a new project or to retrofit an actual operation. These solutions should be based on a business analysis that set a value of information matching the contribution of precious metals as well as the potential to use such information to act toward increasing plant profitability. Conclusions are that trade-offs are an inherent part of the design/audit/retrofit of any metal accounting system in any plant processing either base or precious metals. However, compromises must be evaluated on economic/technical ground.INTRODUCTION Every mineral processing plant must produce metal accounting reports (Morrison, 2008) where estimated saleable metal flows and inventories are published. These metal accounting reports are delivered to a variety of stakeholders who use them for internal management purposes (day-to-day plant production planning, plant operation optimization, capital spending, etc.) as well as for external management (royalty settlements, tolling agreements, etc.). Hence, there should be no doubt that state of the art metal accounting is instrumental for mining companies to reach and sustain high-quality corporate governance (Gaylard, Randolph, & Wortley, 2014). However, producing a metal accounting report involves much more than just printing it (Lachance, Leroux, & Gariépy, 2015a). The underlying metal accounting system (Figure 1) is responsible not only for the reliable production of the metal accounting reports but also for the quality of the outcome. As such, the crucial tasks of its design/audit/retrofit should neither be seen as ancillary nor be left as an afterthought."

Jan 1, 2017

By E. Peek, L. Becze, K. Reading

"Gallium oxide is an important semiconductor material used in optoelectronic devices (flat panel and solar cell) catalysts and sensors. One of the methods to produce ?-Ga2O3 is the so-called hydrothermal route. It is practiced by Neo Gallium Compounds and comprises of two steps: (1) the production of mainly gallium-oxy-hydroxide in a pressure vessel by reacting metallic gallium with water at 200-220 ºC and (2) the calcination of gallium-oxy-hydroxide at 700-750 ºC to convert it into ?-Ga2O3. This paper describes this pressure hydrometallurgy process supported with relevant thermodynamic data and presents the characteristics of the ?-Ga2O3 powder produced for commercial purposes. INTRODUCTIONGallium is a relatively new metal, having been predicted by D. Mendeleev in 1871, discovered by P.E. Lecoq de Boisbaudran in 1875, and first commercially produced in the USA in 1943. Gallium is not rare, being more abundant in the earth crust than antimony, bismuth, molybdenum, silver and tungsten. However, few gallium minerals exist in nature, and the dispersion of gallium within other minerals add to the complexity of its recovery. In practice, gallium is found in dispersed state primarily in bauxites and in some sphalerites, and, to a much smaller extent, in some coals. At present, a very large proportion of the primary gallium in the world is recovered as a by-product of aluminum plants, mostly Bayer plants, where gallium is extracted from a bleed of the Bayer liquor (Roskill, 2011). In 2011, world production of primary gallium was estimated at 200 metric tonnes. In addition, there is a significant contribution of recycling to the overall yearly availability of the metal.Gallium exhibits fairly remarkable properties: it is liquid above 29.76 ºC, can be supercooled, and with its high boiling point (2204 ºC), is the metal with the widest liquid range. Gallium is magnetic, and is an excellent conductor of both heat and electricity. Gallium also displays a marked anisotropic electrical conductivity (Roskill, 2011). All these properties render gallium almost irreplaceable in the semiconductors (GaAs, GaN, GaSb, GaP wafers) and the optoelectronics industry (flat panel, solar cell)."

Jan 1, 2012

By Morgan Schauerte, Laura Raimondi, Mariel Palomeque

Executives in the mining industry are facing dramatically changing market expectations on reporting and transparency regarding the environmental and social impacts of projects, supply chains and products. Companies increasingly need to disclose the governance procedures they have in place to ensure communities, investors, employees, and Indigenous partners are effectively managing social and environmental risks. These disclosure requirements begin during exploration and carry through to all stages along the project life cycle. This type of environmental, social and governance (ESG) disclosure is referred to as ESG performance by the investment community. ESG is not a new concept, and it builds on and is intertwined with many concepts such as corporate sustainability, corporate social responsibility, eco-efficiency, triple bottom line thinking, life cycle management and many others. This paper will explore how mining companies can develop a credible ESG governance approach and strategy that will reduce risk, open opportunities, and create value. This paper will summarise ESG trends and drivers, discuss the economics and investors’ perspective towards ESG, and outline leading ESG standards and guidelines of interest to investors, regulators, communities and other stakeholders. Linkage of ESG to global sustainability efforts such the United Nations Sustainable Development Goals and Global Compact will also be addressed.

Jan 1, 2023

By A. M. Cann, C. I. Godwin

"The Kemess porphyry copper-molybdenum deposit occurs in the Intermontane Belt of north-central British Columbia. The deposit is in andesitic to basaltic flows and tuffs which may be correlated with the Savage Mountain Formation of the Upper Triassic Takla Group. Most known chalcopyrite and molybdenite is associated closely with a 500-m-diameter zone of intense quartz-sericite-pyrite alteration. A zone of supergene enrichment, up to 30 m thick, underlies a leached capping about 20 m thick. The age of mineralization and the surrounding granodiorite and quartz monzonite pluton is Early Jurassic. K-Ar and Rb-Sr analyses indicate that the mineralization and alteration is slightly younger (l82±6 Ma) than the granitic intrusion (KAr: about 205±6 Ma; Rb-Sr: 190±4 Ma). The low 87Sr/J6Sr initial ratio for the granodiorite is typical of plutons in the Intermontane Belt.IntroductionKemess is a medium to small porphyry copper-molybdenum deposit with significant gold and silver values (Pilcher and McDougall, 1976). This paper describes the lithologies and alteration at this property; geochronology by Rb-Sr and K-Ar methods defines the ages of mineralization and surrounding plutons to be Early Jurassic.The property, located in the Thutade Lake area of northcentral British Columbia (NTS Map 94E; lat. 57°04'N; long. 126°44'W), is about 425 km northwest of Prince George (Fig. 1). Closest road access is 35 km southeast of Kemess. Final access must be by float plane or helicopter. The British Columbia Railway right of way passes 70 km to the southwest of theproperty.A prominent gossan zone at Kemess was staked in 1967 by Kennco Explorations (Western) Ltd. following detection of geochemical anomalies during stream sampling the previous year. During 1968, 1969and 1971, Kennco completed 232 m of X-ray diamond drilling, conducted geological mapping and carried out geochemical sampling of silts and soils (Stevenson, 1969; B.C. Ministry of Energy, Mines and Petroleum Resources, G.E .M., 1969 and 1971). Getty Mines Ltd. optioned Kemess in 1975and 1976. They remapped the area and diamond drilled 12 BQ and NQ holes, totalling 2065 m (B.C. Ministry of Energy, Mines and Petroleum Resources, Expl. B.C., 1975)."

Jan 1, 1980

By R. J. Grant, D. W. Scott, M. A. Cooper, E. R. Shannon

"The Brunswick No.12 site concentrator processes 10,500 tonnes per day of a complex lead, zinc, copper and silver ore producing four concentrates by differential flotation. Research over the years has led to increased understanding about the mineralogical and flotation characteristics of the ore. A pilot plant study conducted at Lakefield Research, primarily designed to investigate the technical feasibility of semi-autogenous grinding, provided an opportunity to test recent theories about grind size,, reagent schedule and flowsheet configuration.A fundamental approach was taken with each of the unit processes involved in grinding and flotation. Basic operating and metallurgical criteria were established in each area and a step-by-step implementation program initiated in the plant.Significant improvements in metallurgical and financial performance have been realized through the application of basic grinding and flotation principles using conventional milling equipment and without major capital expenditure. Current operating practice is detailed and metallurgical advancements cited.INTRODUCTIONBrunswick Mining and Smelting operates one of the world's largest lead and zinc mines near Bathurst, New Brunswick. Brunswick is a publicly traded company with majority ownership held by Noranda Minerals (63%). In addition to the No. 12 underground mine, the company operates a lead smelter and phosphate fertilizer plant in Belledune, N.B. and maintains a 25% interest in a joint venture with Noranda Minerals' Heath Steele mine near Newcastle, N.B. Through the four operations, a total of 2000 people are directly employed with fixed assets totalling Cdn$187 million (BM&S, 1991)."

Jan 1, 1993

By Fred W. Snow

THE mines of the Consolidated Copper and Sulphur Company, consisting of the Eust1s, the Albert, and the Capel mines, are situated w Ascot township, Quebec, about ten miles southeast of Sherbrooke, on the main line of the Quebec Central railway. Of these mines, only the Eustis is now producing, and it has been operated almost continuously for the past seventy years. Mining methods have been improved in recent years but are still old fashioned when compared with those employed in more modern and up-to-date mines. The ore is of milling grade and is mined for its copper and sulphur con-tent. Silver is present in small quantity, together with a trace of gold. The ore is mined by the shrinkage stope method. Pillars are frequently left as supports for the hanging-wall to prevent serious dilution of the ore and are sometimes recovered after the ore is drawn from the stope. Occasionally, small blacks of ore in close proximity to the shaft are mined by a cut-and-fill method. HISTORY ALBERT AND CAPEL MINES: The Albert and the Capel mines, originally known as the Capelton mine, were discovered in 1863 by George Capel (1). By the end of 1866 the Albert shaft had been sunk to a depth of 121 feet on an incline of about 30 degrees where a vein five feet thick was encountered. In 1879, these mines passed into the hands of G. H. Nichols and Company, by whom they were operated practically continuously until 1907. When mining operations ceased in that year, the shafts had reached depths on the incline of approximately 2,300 feet and 1,000 feet, respectively. These mines have been allowed to cave and fill with water and have been inaccessible for many years.

Jan 1, 1936

By A. M. Christie

Acknowledgements The following account has been compiled mainly from records and maps of Eldorado Mining and Refining (1944), Limited, hereinafter called the Crown Company. This work was done under the supervision first of R. F. Murphy, Chief Geologist, and later of E. B. Gillanders, Eldorado Mine Manager and Manager of Eldorado Exploration Division. W. F. James and B. S. W. Buffam are consulting geologists. Since 1946, S. N. Kesten has supervised geological work for the Company in the Goldfields area. Where maps of Eldorado properties have been included in this paper, the name of the geologist who examined the property is acknowledged on the map. Outline of General Geology The geology of the area is described in the Goldfields and Martin Lake preliminary maps of the Geological Survey and accompanying Paper 49-17. In brief, the Tazin series of Precambrian age, consisting mainly of sediments with minor interbedded volcanics and basic intrusives, is intruded and replaced by granite, now generally gneissic. The late-Precambrian Athabaska series of conglomerate and arkose, with interbedded basalt and andesite flows, rests unconformably on the older rocks. All these rocks are cut by small diabase dykes. The geological terms used in this paper and in the accompanying figures are standard with the exception of the term 'mafic rocks'. These include all the basic or dark coloured rocks of the Tazin group, such as amphibolites, biotite schists, and chlorite-epidote rocks (greenstones), whether they be of extrusive, intrusive, or sedimentary origin.

Jan 1, 1949

By R. M. Beauchamp

Base metal processing operations often treat process tailings and acid mine drainage using a high density sludge (HDS) water treatment process. Lime is used in this process, which reacts with existing sulfates to form gypsum. When a recycle stream is incorporated in the process, gypsum levels in recirculating water may build up and cause high levels of gypsum supersaturation. Precipitation of gypsum from the supersaturated process water causes many problems. It is speculated that gypsum may precipitate on sulfide minerals and silica gangues in the flotation circuit, resulting in decreased selectivity and recovery. An understanding of the determinants and nature of precipitation may provide solutions to mitigate the formation of precipitates and improve flotation performance. This study showed that both sphalerite and silica exhibited gypsum- or calcium carbonate-like behavior in the respective supersaturated solutions, indicative of a coating of calcium species on the mineral particle surfaces. The addition of copper sulfate and/or potassium xanthate had little effect on the precipitation of gypsum or calcium carbonate on the mineral particles. Sodium carbonate is encouraging as a method to minimize calcium species interactions on sphalerite/silica surfaces.

Jan 1, 2006

By James J. Scott

"In the two years since their introduction, Friction Rock Stabilizershave replaced40 per cent of the previously used fixtures in the metal and non-metal mines in the United States. The Friction Rock Stabilizer, or ""Split Set "" , is a mechanical rock stabilizing system which uses friction to prevent rock movement . The Split Set is a tapered, rolled, steel tube that is slotted along its length. As it is driven into a drilled hole smaller than its diameter, it compresses, pre-loading the surrounding rock. This paper discusses the uses and acceptance of the friction rock stabilizer in mines in the United States. IntroductionFriction Rock Stabilizers, commonly called Split Set™· Stabilizers, have been under development by the author and Ingersoll-Rand Company since early 1973. Five years of intensive laboratory and field testing led to their introduction to the metal mines in the United States in the fall of 1976. Actual sales started in February of 1977and, to date, over five million units have been marketed to metal mines. The present rate of usage is near 3 V2 million units per year, which is approximately 50070 of all roof fixtures used in the United States metal mining industry,Richard Hoppe, senior editor of Engineering & Mining Journal. , in an article in the February 1979 issue entitled ""Winning the Battle Against Bad Ground"", said: ""In hardrock mining operations in the western U.S., particularly underground uranium mines where exceedingly difficult ground is common, no roof support system has been accepted more quickly than the Split Set friction bolt invented by Dr. James J . Scott and developed by Ingersoll-Rand Co."" This paper describes how Friction Rock Stabilizers function and presents technical data to show the uniqueness of such systems."

Jan 1, 1980

By T. S. Smith, C. C. Rennie

"THE LEAD-ZINC and tungsten mines of Canadian Exploration Ltd are on Iron Mountain, 8 miles south of Salmo, B.C., in the Nelson mining division. Relative location of the mines is shown on the general plan.First recorded lead production was in 1908 from surface outcrops. Small amounts of high lead ore were mined intermittently until 1926. No major lead-zinc production occurred until 1949 when outcroppings on the south side of the mountain were mined and diamond drilling began to prove the existence of a large replacement orebody. Lead-zinc ore has been mined continuously from the Jersey orebodies since March 1949, with monthly tonnage as high as 50,000 tons per month, but currently averaging 30,000 tons per month.Schee1ite-bearing tungsten ore was found in 1942 by H. Lakes in an old adit and open cuts at the north end of the Emerald tungsten orebody. The Emerald tungsten mine was developed by the Federal Government as a Wartime Metals project and operated for eight weeks in the fall of 1943, when the poor demand for tungsten closed the mine. Canadian Exploration Ltd. purchased the mine in 1947 and mined in excess of 100,000 tons in 1947-48 until the demand for tungsten dropped again and interest was centred on lead-zinc. The Federal Government repurchased and reopened the Emerald Mine in 195 L and built a new concentrator. The mine and mill were sold back to Canadian Exploration Ltd. in 1952.Regional Geology and IntrusivesThe host rock for both the lead-zinc and tungsten mineralization is the Laib formation of Lower Cambrian age, which consists of 400 feet of crystalline limestone underlain by beds of argillite, and argillaceous limestone locally altered to ""skarn"" or ""tactite"". The Laib limestone is overlain by black argillite and underlain by the Reno quartzite of Pre- cambrian age. Repetition of folded beds has allowed the interpretation of the large isoclinal fold which repeats the limestone (see general cross-section). Dolomitization and the associated lead-zinc ore have been found only in the right-side-up limestone and are not known in the overturned limestone.Two elongated stocks of granite cut the sediments. The Emerald stock outcrops along the east side of the Emerald tungsten mine and again west of the Jersey workings, while the Dodger stock outcrops only at the north end of the Iron Mountain. The shape and attitude of these bodies are believed to have been governed partly by pre-granite faulting and partly by pre-granite folding of the sediments. Although some forceful intrusion may have occurred the detailed granite surface indicates a gentle stoping emplacement."

Jan 1, 1949

By Douglas R. Piteau

"Assessing the stability of a slope cut in rock is basically a problem of engineering geology - geology, because it involves a sound understanding of the important aspects of geology, such as geological structure, ground water, weathering and other natural phenomena, which all relate to or exist in a geological environment, and engineering, in that quantitative evaluations and calculations are necessary, these being based on mechanics and relating to the strength of the geological materials and the forces causing instability of the slopes. The engineering geologist must make every attempt to. provide, in a quantitative way, information on those geological factors which are necessary for making calculations of the probable stability of the slope. These include numerical assessments of quantities relating to the characteristics of structural discontinuities, rock types, topography, hydrogeology, tectonic history and other environmental factors. Based on the development and extension of these general principles, both preliminary and final slope stability studies of some open pits in South Africa, Swaziland and Zambia have been conducted. Some of the basic concepts and techniques developed to carry these studies out are described."

Jan 1, 1972

By E. W. Williams

THE Ontario Research Foundation has developed a process for producing low-density steel shapes by direct reduction of iron oxide powders. The process is a combination of reduction, sintering (without compaction), and carburizing, and has been described by Cavanagh (1). Iron oxide powder, in the form of mill scale or highly concentrated iron ore, carefully sized, is poured into a porous mould. A reducing agent, generally coke breeze, is placed around this mould in a heat resistant sagger which is sealed off and heated to 2,000°F. for a number of hours. The coke/ ore ratio, the particle size distribution, the temperature and time of soaking, and the size and shape of the reduced product, determine the densities and carbon contents attained. The Defence Research Board sponsored a programme of research into some of the mechanical properties of the material (which was named Controlled Density Steel) and this paper is an account of various factors which govern the tensile strength of the steel. The ?practically attainable range of density is from 1.5 to 5.5 gm./ cc. but higher densities are obtained on hot working. This paper, however, is restricted to discussion of results for moulded products.

Jan 1, 1957