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By J. Walenzyk

This report investigates the limited use of super large backhoes in surface mines around the world. The demand for super large (> 700 t) hydraulic excavators is rising and most of the machines are sold as front shovel (FS) application. Despite advantages in faster cycle times super large backhoe (BH) machines are a minority (ca. 1% of the total machine population). This investigation is based upon the comparison between the volumes available to the BH and FS in one block and before the machine needs to move. The working conditions are created with standard parameters as given by Original Equipment Manufacturers of hydraulic excavators regarding bench height, angle, and material density. The travel amount of both machine types is derived from these volumes and compared. Furthermore, the travel amount of super large BHs is compared to the travel amount of smaller mining BHs and evaluated based on attachment length and bucket size. The calculations conclude that the volume of material recoverable in a single spot is about 75% higher for FSs. This leads to an increased travel for BHs. The combination of both the increased appearance of electrical driven machines (in the class of > 700 t excavators) and the travel amount lead to a high risk of damaging the cable or the excavator. Enlarged wear on the travelling parts is also attended by the higher travelling. A direct comparison of commonly found working set ups shows that the ratio between volumes is 32% which leads to an increased travel amount. In comparison with a 250 t BH, the calculation shows that the smaller BH is able to reach nearly 50% of the volume of the super large BHs. The main reason for this is the respectively high reach on smaller machines which, combined with other factors, leads to a significantly higher number of BHs in lighter classes.

Aug 1, 2013

By R. D. Studer

"The Snow Lake massive sulphide deposits are hosted by Aphebian volcanic rocks of the Flin Flon - Snow Lake greenstone belt, which in this area were deformed and metamorphosed to the amphibolite facies during the Hudsonian orogeny. All the known deposits occur in felsic rocks a short distance below the contact with an overlying mafic rock unit.The Stall Lake copper deposit occurs close to the top of an explosive felsic volcanic sequence. Rocks stratigraphically underlying the deposit have been hydrothermally altered by the mineralizing fluids. The sulphides were probably deposited from submarine volcanic vent(s) on the flanks of a felsic dome. The ore has been tightly folded, flattened and elongated parallel to the northerly trending lineation of the surrounding rocks during the several periods of deformation. Strike lengths of the lenses range from 60 to 300 feet and plunge-to-strike ratios are as much as 15:1.Ore lenses 1 to 4 typically consist of massive coarse-grained pyrrhotite, chalcopyrite and pyrite. A stratigraphically higher lens differs in that it contains fine-grained pyrite and chalcopyrite, with an increase in sphalerite toward its hanging wall. The No.4 orebody has a distinct footwall alteration zone characterized by brecciation and abundant chlorite-staurolite-garnet schist, with minor kyanite, anthophyllite, cordieriteand anhydrite, as well as sulphide minerals. Chemically, the alteration zone is distinguished from the unaltered felsic rocks by Na20 depletion and Mg-Fe enrichment.IntroductionThe Stall Lake copper deposit is located aproximately 4 miles southeast of Snow Lake in northern Manitoba (Fig. 1). The Snow Lake district has been a producer of gold (Rex, Bingo, Laguana and Nor-Acme Mines) and, since the fifties, of copper and zinc from deposits of Hudson Bay Mining & Smelting Co., Ltd . The district is located near the eastern limit of the Flin Flon - Snow Lake greenstone belt, which contains Amisk metavolcanic rocks of Aphebian age."

Jan 1, 1982

By G. H. Blackwell, A. J. Sinclair

"The main components of a ""PC” -based mineral inventory system are described in a sequence common to many real reserve/ resource estimation projects and in the practical context of problems and decision-making typically encountered in such studies. Some components are designed particuarly to improve the geostatistical instructional capability of the package. An important part of this approach involves the use of widely available software for data manipulation and evaluation in the design of a mineral inventory study progressing to mine design and feasibility. A variety of more or- less fixed routines written in high level languages provide acceptable computational speeds on a personal computer. These critical segments are linked by simple, short, compiled Basic programs easily adjustable to various data configurations and needs. IntroductionGeostatistical mineral inventory estimation has progressed greatly since its slow dissemination during the 1960s. The mining industry generally has accepted the benefits of the technique, notably the quantification of grade and geology, an indication of error in grade estimation, and of the mined volume / grade variance relationship (Clark, 1979, Isaacs and Srivastava, 1989).Acceptance has been slowed, first by complexities of geostatistical theory and second by a bewildering variety of computer systems and applications programs. Continuing improvements in education will facilitate a better understanding of the underlying theory.The purpose of this paper is to describe, in a practical context, the development of a geostatistical-based approach to reserve/resource estimation. The approach integrates various existing commercial software packages with a wide selection of programs developed by the authors for personal computers which estimate mineral inventories and educate users in the techniques applied; that is, the QMIN system.It is hoped that the approach presented here will convince mining and geological engineers concerned with resource estimation, of the soundness of geostatistical methods and its broad potential to their problems."

Jan 1, 1992

By S. I. Vobnout, J. Wm. White, J. P. Olson

"Mine management now recognizes the value of computer-based truck-shovel dispatching in open pit mines. The key tangible benefits are substantial productivity increases with a given fleet of equipment or, alternately, significant reductions in equipment required to meet production quotas. In this paper, the authors review the literature, report on efficient, optimal algorithms for haul truck dispatching in real-time, and briefly discuss methods used by various mines to evaluate productivity improvements over manual methods. Actual results obtained at thirteen mining operations around the world are also presented.IntroductionModular Mining Systems manufactures, installs, and supports its computer-based DISPATCH system at mines worldwide. DISPATCH is a large scale, computer-based mine management system which controls the dispatching of all haul trucks in any open pit mine (Fig. 1). When increased production is important, DISPATCH gets the needed production increase with fewer new or recommissioned trucks. DISPATCH also helps operations meet its blending objectives while minimizing rehandle and maintaining production. Furthermore, DISPATCH includes a powerful, eventdriven simulation subsystem. With the simulator mine management can pose ""what if' situations and see the predicted effect on production"

Jan 1, 1993

"The Society for Mining, Metallurgy, and Exploration (SME) Inc. developed a guide of minimum standards for reporting exploration results, mineral resources, and mineral reserves for the purpose of informing the general public. The SME Guide has been adopted by the Society.History1. In 1988, at the request of members of the Society for Mining, Metallurgy, and Exploration (SME), Inc., the President of SME formed Working Party #79, Ore Reserve Definition, with the mission to develop guidelines for the public reporting of exploration results, resources, and reserves. A Subcommittee was appointed by the Working Party to draft these guidelines and submit recommendations to SME. The Subcommittee's recommendations were published by SME in the April 1991 issue of ""Mining Engineering"", and as a document entitled ""A Guide for Reporting Exploration Information, Resources, and Reserves"" (the SME Guide) in January 1992. Work continued on an ad-hoc basis until 1996, when Working Party #79 was renamed the SME Resources and Reserves Committee and became a standing committee.In 1994, the Council of Mining and Metallurgical Institutions (CMMI) started a concerted international effort to create a set of international definitions for reporting mineral resources and mineral reserves. An ad-hoc International Definitions Group was formed, with representatives from mining and metallurgical institutions from the United States (SME), Australia (AusIMM), Canada (CIM), the United Kingdom (IMM) and South Africa (SAIMM). A major breakthrough came on October 18, 1997 when the CMMI International Definitions Group met in Denver, Colorado and reached a provisional agreement (the Denver Accord) on definitions of mineral resources and mineral reserves. Concurrently, and since 1992, the United Nations Economic Commission for Europe (UN-ECE) was developing an international framework classification for mineral resources and mineral reserves. Starting in October 1998, joint meetings were held in Geneva between the CMMI International Definitions Group and the UN-ECE Task Force, resulting in agreement to incorporate the CMMI definitions into the UN framework classification."

Jan 1, 2003

By Jean-Yve Tremblay, Michel Prud'homme

"IntroductionIndustrial minerals include a group of more than fifty minerals which are marketed into almost all the sectors of industry; they are the backbone of many manufacturing industries. Table I shows major end-uses for industrial minerals in manufacturing sectors.At Energy, Mines and Resources, industrial minerals are divided in three major categories: (I) agro chemicals and chemicals, (2) construction mineral s, and (3) ceramics and specialty minerals. A listing of the major groups of minerals is shown in Table 2.Agro-chemicals and chemicals are sold on the basis of their chemical content and purity. Construction minerals or structural minerals are distinguished by their performance as low cost and bulky commodities. Ceramics and specialty minerals are performance-specific and are sold for their property on imparting functions on end-products. Industrial minerals have unique characteristics that are useful in many stages of processing; from crushed size to micronized fillers a single mineral ca n serve a broad range of industries because of its intrinsic properties.The Industrial Minerals Industry in CanadaCanada has a large industrial minerals base and is a world leader in the production of some of them. The total value of product ion of these minerals has grown by 115% over the last 10 years despite the misfortune of asbestos.Industrial minerals have shown remarkable growth in the past 20 years at an average annual rate of 9.2%, compared to 7.8% for metallic minerals. In 1986, the value of industrial minerals rose to $4.9 billion, or 14% share of the Canadian mineral production. Figure I shows the value of production of the mineral industry for the period 1966-1986.The leading segment in industrial minerals segment since 1976 is the chemicals and agro-chemicals sector which has an average annual growth rate of 5.75 % in terms of value of production. During the same period, the growth rate for the whole Canadian mining industry was 1.37% per annum. The chemicals and agro-chemical s sector increased its contribution to the total value of production of 2% to 6070 despite the growing share of fuel minerals with 59%."

Jan 1, 1988

By R. A. Gannicott

Trend surface analysis was used to investigate the geochemical dispersion patterns of Si, Ai, Fe, Mg, Ca, Na, K, Ti and Rb in the footwall of the Seneca massive sulphide prospect in southwestern British Columbia. Surfaces for various element ratios were also produced to see if the distributions of the elements are related to each other. Trends developed by the elements redistributed during hydrothermal alteration may be difficult to detect for various reasons, such as too few and widely separated sample points, random analytical errors or local variations in rock chemical composition that are not related to regional trends. Trend surface analysis is useful to distinguish regional trends from local fluctuations. The computer program used in this study is capable of calculating surfaces up to the 6th degree polynomial, but provides for automatic termination when the variables in the equation for successive surfaces become effectively collinear. With the relatively small number of data points used (21 samples) in this study, such termination occurred after the quadratic surface. Results show that, at the Seneca prospect, Mg and K increase, and Na and Ca decrease, toward a common centre which corresponds closely with the best drill-core intersections of ore. The centre is interpreted as a volcanic vent and as the source of mineralization . Quadratic surfaces for element ratios show that K/Ca decreases and Fe/Mg increases away from this vent. Thin-section and X-ray diffraction analyses indicate that these variations reflect sericitization of plagioclase and an increase in the Mg content of chlorite near the vent. The mineralization , rock types and element dispersion patterns at the Seneca prospect are similar to those reported for volcanogenic massive sulphide deposits at Bathurst, New Brunswick, and in the Hokuroko district of Japan.

Jan 1, 1979

By Waghmarem Umesh V., Vinay Jain, Pradip, Beena Rai

"The hematite surface plays a vital role in several processes of industrial and technological importance, such as, in beneficiation of iron ores, catalysis, and geochemical processes. Therefore, it is imperative to have a clear description of the structure and composition of this surface, which forms the underlying basis for such a wide variety of complex phenomena. Particularly, from the perspective of beneficiation of Indian alumina-rich iron ore slimes and fines, a clear understanding of the surface structure and composition of hematite surface and its difference from the alumina surface will facilitate identification and/or design of selective reagents which can be used to separate the two minerals. In this work, the hydroxylated hematite (0001) surface was modeled using density functional theory (DFT). The computed planar relaxations are consistent with X-Ray crystal truncation rod diffraction results reported in the literature. It is demonstrated that only one type of surface, that is, the (OH)3-Fe-H3O3-R is stable under aqueous conditions, as the relaxations for the second type of termination: (OH)3-Fe-Fe-R do not match quantitatively with experiments suggesting that its coexistence with the (OH)3-Fe-H3O3-R surface is unlikely. A detailed analysis of this surface shows that two of the three (OH) groups are not connected to the Fe surface atom. Instead, they form H2O molecules by combining with the H-atoms on the O-layer beneath the Fe-terminated surface leaving the Fe surface-atom bonded to only one OH-group. This undercoordination of Fe-atoms on the surface explains its higher reactivity as compared to hydroxylated alumina.INTRODUCTIONThe hematite surface plays a vital role in several processes of industrial and technological importance. A few examples are: flocculation/froth flotation of iron ores (Ravishankar, Pradip & Khosla, 1995), catalysis (Muhler, Schlögl & Ertl, 1992; Samsonov, 1973), and geochemical processes (Brown, Henrich, Casey, Clark, Eggleston & Felmy et al., 1999; Sposito, 1989). Therefore, it is imperative to have a clear description of the structure and composition of the hematite surface, which form the underlying basis for such a wide variety of complex phenomena. Particularly, from the perspective of beneficiation of Indian alumina-rich iron ore slimes and fines, this is an important problem, as a clear understanding of the surface structure and composition of hematite surface and its difference from the alumina surface will facilitate identification and/or design of selective reagents which can be used to separate the two minerals. Our current research focus is at employing molecular modeling techniques to come up with such selective reagents and then test their efficacy in the practical scenario through selective dispersion – flocculation labscale experiments and subsequently plant trials. Obviously, the correct structure and composition of the hydroxylated hematite surface is a fundamental prerequisite for such investigations."

Jan 1, 2016

By L. Kilpinen, K. R. Kay, H. B. Fowler

"FOREWORDThe International Nickel Company of Canada has built four ore concentrating plants since 1950. The fifth and largest is now under construction. In each successive plant, the level and type of instrument control and sophistication of control techniques have increased as experience was gained. The type of control progress is illustrated in Fig. 1.At Frood-Stobie the high degree of instrumentation and the level of control were made possible by the constant evolution of techniques and improved instrument hardware technology. We have established in practice concepts that are sound, although many modifications to instrument sensor types and locations 1-rere often necessary. It is generally true that at other existing Inco mills, it is possible to run ""all manual"" for protracted lengths of time because of operator availability and dependence. The Frood-Stobie Mill is the exception, and it is the degree of reliability of the instrumentation hardware and level of maintenance that has made this possible."

Jan 1, 1971

By N. Dave

"IntroductionIn the mineral processing industry, certain minerals such as uranium, thorium and vanadium, etc., are selectively extracted with high degree of purity from solutions containing variety of other impurities by solvent extraction process. This separation process consists of bringing two immiscible or partially soluble liquid phases in contact, where mass transfer of one or more components takes place by ion exchange under certain controlling parameters such as pH, salt concentration and temperature. The processes taking place are primarily physical because the solutes being transferred are ordinarily recovered without chemical change. For efficient extraction more than one stage is required and the solutions are recycled counter currently through other stages. A multi-stage counter current solvent extraction plants essentially consist of four circuits namely: extraction, water wash, stripping, and solvent scrubbing. In extraction circuit the desired mineral is extracted at a certain pH from an aqueous solution onto an organic solvent by bringing them in contact with mixing in large mixer-settler units. The mixed solutions are allowed to settle and separate into component organic and aqueous phases in horizontal settlers by providing sufficient residence time. The solutions are then moved counter currently to other units- the aqueous from the underflow and the solvent organics from the overflow of the settler. The solution streams coming out of extraction circuit are loaded organics and barren aqueous or raffinate solution. The loaded organics are washed with water in a water wash circuit to remove transported impurities from extraction circuit. In the stripping circuit, the desired mineral is stripped selectively from the solvent phase back into an aqueous phase with a stripping agent at a selected pH. The solution stream leaving, stripping circuit are stripped organics and pregnant strip (aqueous) solution. The stripped organics are scrubbed off other loaded impurities with a conditioning solution in, scrubbing circuit and the cleaned solvent is re-used in the extraction circuit.A typical solvent extraction plant for uranium extraction and purification at Agnew Lake Mine is described in this chapter."

Jan 1, 1989

By A. W. Johnston, R. E. Barrett

"The Central Patricia mine is in the greenstone belt north of lake Sc. Joseph in northwestern Ontario. It is 90 miles north of Allanwater on the Canadian National railway and 220 miles east of the Manitoba boundary. The unusual feature of the ore of this mine is that the gold does not occur in quartz but in sulphide minerals filling fractures in iron formation.AREAL GEOLOGYThe rocks of the area in which the mine occurs belong to the Early Precambrian. They consist · of andesite lavas and tuff interbedded with greywacke-like sediments and iron formation . A siliceous phase of the sediments lying north and south of the greywacke enclosing the ore-bearing iron formation in places resembles a sheared and sericitized quartz porphyry. This is shown in the legend of Fig. 1 as quartz porphyry and quartzite, but it is possible that the quartz porphyry-like phase is sediment. A northwest- striking dyke of diabase crosses the property 3,000 feet east of the shaft ( Fig. 1).IRON FORMATIONAlthough there are numerous bands of iron formation in the v1cm1ty of the mine, ore has been found to date in only one main and two lesser zones. The iron formation bands range in width from a few inches to 60 feet, and are interrupted along their strike by gaps that are parallel and rake to the east at about 65°. The iron formation is definitely banded and laminated."

Jan 1, 1954

By Desmond M. Levins

"Australia has almost twenty per cent of the Western World's low-cost uranium reserves, located mostly in the Alligator Rivers region of the Northern Territory. At present, only one uranium mill is operating in Australia, but a number of new mills are planned for the early 1980s.Details are given of Australian uranium mining and milling proposals and the measures taken to minimize their environmental impact. Major factors affecting environmental impact are discussed, including treatment of liquid wastes, water management, control of radon and other airborne releases, and disposal of tailings. IntroductionAustralia is entering a new phase in uranium mining and milling activity . In the first phase of operations, between 1954 and 1971, about 10,000 tonnes of yellowcake was produced at five locations. Most of the production came from the mines at Rum Jungle in the Northern Territory and Mary Kathleen in Queensland. In the 1960s, the demand for uranium slumped, and much of the yellowcake produced at Rum Jungle was stockpiled by the Australian Atomic Energy Commission. The early uranium processing operations in Australia were typical of overseas practice at that time. Environmental problems were generally given low priority and pollution control measures were unacceptable by today's standards. There was little or no recycling of process water, acid waste streams were not neutralized and tailings dams were poorly designed. At Rum Jungle, oxidation of sulphides in waste heaps, tailings dumps and ore stockpiles subsequently led to destruction of vegetation and heavy metal pollution in a nearby river.In the early 1970s, major uranium deposits were discovered in the Alligator Rivers region of the Northern Territory. Significant orebodies were also located in the Great Artesian Basin in South Australia, in calcrete formations in Western Australia and at several locations in Northern Queensland. According to latest available estimates. Australia has about 160/0 of the Western World's uranium recoverable below $US 80 per kg U. Mining these orebodies will require pollution control measures more stringent than practised previously in Australia."

Jan 1, 1980

By Stanley G. Butcher

Predictions of coal cleaning plant performance from the washability data are traditionally used at the conceptual design stage of a coal preparation plant to confirm process selection. The development of computer programs which simulate the operation of a plant facilitates the optimization of product yield and quality, and ultimately proceeds. It is shown that the optimum is sensitive to changes in mine operations and market price structure. A computerized review of operations is thus recommended as an on-going activity .

Jan 1, 1979

By J. R. Johanson, A. W. Jenike

"A solid flows out of a bin provided that the outlet is sufficiently large so that stable obstructions to flow do not develop. The geometry and surface finish of a bin and the construction of the feeder determine the type of flow pattern which then develops within the bin. The pattern, in turn, affects the uniformity and consistency of the stream, segregation, caking, degradation, live capacity and the action of level measuring devices.In most bins now in operation, material flows toward the feeder through a channel which forms within the stationary solid. This is referred to as funnel flow. If the hopper of the bin is sufficiently steep and smooth and the feeder capable of drawing material across the whole area of the outlet, all the solid flows whenever the feeder is in operation; this is referred to as mass flow. Mass-flow bins are usually far superior to funnel-flow bins; their initial cost is also usually higher.The paper describes the design criteria used in deter-mining the minimum bin outlet needed for flow and the bin geometry needed for mass flow."

Jan 1, 1970

By E. Ghali, A. D. Bas

"Treatment of oxide, e.g. roasted gold ores has received relatively less attention than sulphidic ones and recently, handling of oxide gold ores is becoming essential. In this study, the influence of roasted gold ore (RGO) slurry (at 35% solid ratio) on the electrochemical dissolution of gold has been examined using pure gold and iron oxide minerals (hematite, maghemite, and magnetite) as disc electrodes by zeroresistance ammeter mode either in one or two separate containers. The presence of slurry decreased galvanic currents, i.e. corrosion rates due to the release and increase in the amount of soluble and/or insoluble species that could retard further the anodic behaviour of gold. Higher galvanic currents were observed in two separate containers than that in one container indicating the primary importance of galvanic interactions. SEM-EDS results observed iron hydro/oxide coatings on gold surface in case of magnetite test. However, in case of RGO electrode it is not a perfect passivation, although somewhat decreasing trend was observed on gold dissolution. These findings have revealed that passivation is not only a laboratory phenomenon, but also it could be responsible for the slowdown of gold dissolution in industrial practice.INTRODUCTIONThe cyanidation of gold is an electrochemical corrosion process thus; the dissolution of gold can readily be studied by electrochemical techniques. The outcome/summary of previous electrochemical studies of gold leaching can partially be summarized as follows: Filmer (1982) and Lorenzen and van Deventer (1992) reported the negative effect of pyrite and pyrrhotite on gold leaching due to the galvanic interactions; Aghamirian and Yen (2005) studied gold galvanic corrosion in presence of sulphide mineral electrodes only in one cell using zero-resistance ammeter (ZRA) mode; Dai and Jeffrey (2006) discussed, individually, the anodic and cathodic behaviours between gold and sulphide minerals, and Azizi et al. (2010, 2011) used a bed reactor to examine the influence of sulphide minerals on gold dissolution in one and two separate cells. Accordingly, a slowdown in gold leaching has generally been attributed to the passivation phenomenon, although the indication of this phenomenon is still an undergoing debate. For instance, Mrkusic and Paynter (1970) identified the passivation as the film formation of dissolved species from calcine, Crundwell (2014) explained passivation, in the case of corrosion of metals, as the formation of a layer which is composed of a new chemical species on the mineral surface and this layer inhibits or blocks further reactions. He suggested that passivation is related to the oxidation of the metal, and the formation of a passive layer that retards the rate of dissolution by several orders of magnitude. Consequently, galvanic interactions, passivation phenomena, or combinations of them are considered significant electrochemical factors affecting gold dissolution (van Deventer, Reuter, Lorenzen, & Hoff, 1990; Azizi, Petre, & Larachi, 2012). It is important to note that generalizing the influence of a mineral/metal on gold dissolution may not be correct in all cases, since contrary behaviours/results (for pyrite) have been observed (Aghamirian & Yen, 2005). Therefore, electrochemical study of gold is still a subject of research and need to be examined further in detail."

Jan 1, 2016

By M. D. Gerst

The degree to which copper will continue to be in an integral part of the world economy in the future will depend largely on the dynamics of global economic development, the primary and secondary copper resource stock, technological change, and potential environmental constraints. We have characterized the copper cycle of 1994 for all of Earth's regions and for the planet itself (T. Graedel et al., Environmental Science & Technology, 38, 1242-1252, 2004) and recently updated that cycle to year 2000. In this paper, we compare various features of the 1994 and 2000 cycles. The three largest-using regions, Asia, Europe, and North America, all increased their absolute rate of copper use between 1994 and 2000, and all increased the per-capita rate of copper use as well. Globally, the use of copper increased by about 32%, from 11.7 to 15.3 million metric tons, while population increased by only 8%. Various changes are seen in scrap trade, finished products trade, and other parameters of the cycle. We conclude by considering how the rates of technological change and growth in demand, especially in Asia, may influence the copper cycle in the years ahead.

Jan 1, 2007

By Guillermo Diaz, Roberto Pérez, René del Villar

"Pulp-froth interface position is a key variable in column operation. In plant practice, it is commonly estimated through a system of three pressure-transducers which allows the calculation of the pulp height. An alternate method based on the measurement of the conductivity profile across the interface has been proposed and successfully tested. Both methods however, present some practical problems related to the assumptions made in the calculation of the pulp height in the former case, and to the response time and the precision of the reading in the latter case.In this paper, the use of the neural network technique for improving the estimation of the pulp-froth interface in flotation columns is discussed. The technique is used with both conductivity-based and three pressure-transducer methods. Results obtained in a 2"" laboratory column and a 12"" pilot scale column are presented. A major obstacle in applying this approach in practise is the training of the artificial neural network. This problem is analyzed here for the conductivity-based method and some solutions are proposed."

Jan 1, 1995

By G. F. Miller

ONLY IN THE Province of Saskatchewan is natural sodium sulphate found in Canada in amounts large enough to make recovery economically sound. Geologists have estimated that the numerous deposits within the Province contain upwards of 200 million tons of Glauber's salt. There are twenty-one deposits in the Province which contain 500,-000 or more tons and about two dozen with lesser amounts. The first recorded production of sodium sulphate in Saskatchewan was in 1918. The company concerned, and others that attempted to develop the industry in its early stages, were unsuccessful. Their failures were caused by two main factors -lack of knowledge of efficient operating methods and the unstable market situation for the finished product. Today, the situation is changed in both respects and the product, commonly referred to as 'saltcake", is a very important chemical requirement of many industries throughout the world. Before proceeding with remarks on manufacturing methods it should be stated that, although this is a general paper on the manufacturing methods and end uses of the saltcake produced in the Province, the writer is, of course, more familiar with the plants operated by Saskatchewan Minerals than with other operations and perhaps may be excused for dealing more particularly with the plants of that Compa11y.

Jan 1, 1958

By R. K. Sidhu, N. L. Richards, M. C. Chaturvedi

Nickel base superalloy IN-738LC, strengthened mainly by the precipitation of y' phase, is extensively used in hot sections of land-based and aero gas turbine engines. Fusion welding, which is one of the most commonly used joining techniques for the repair and fabrication of superalloy components, however, finds a very limited application in case of IN-738LC components, as the alloy suffers from HAZ cracking during welding and during subsequent postweld heat treatment (PWHT). The present paper reports on the two methods studied to reduce the HAZ cracking in as-welded and postweld heat treated GTA welded IN-738LC, viz., the use of various fillers during welding, and the use of appropriate heat treatments prior to welding. The results of the microstructural analysis and crack measurements indicated that the HAZ cracking in GTA welds of IN-738LC was significantly reduced by using age-hardenable fillers with Al+Ti concentration less than that in the base metal in conjunction with a preweld heat treatment developed by the authors.

Jan 1, 2006

By Gordon Sparks, Lyle Kajner

"An often over-looked component in the assessed value of a mining property is the value derived from the ability of the operator to limit financial losses during adverse economic times (i.e. low market price, high energy prices, etc.) by suspending operations. Overlooking the value of this type of operating flexibility when conducting mine investment analysis may negatively bias the risk profile for the investment by over estimating the investment's downside potential, thereby effectively undervaluing the investment. This paper illustrates the nature of the value of operating flexibility and discusses how it may be explicitly quantified within the context of conducting stochastic mine investment analysis. IntroductionMining properties are evaluated using an array of techniques ranging from simplistic non-discounted payback calculation s to sophisticated, discounted-stochastic simulation. Stochastic simulation analysis is perhaps the most robust mine investment analysis technique as it not only provides an estimate of the expected value of the property, but also quantifies the associated risks (for examples of stochastic mine investment analysis, see: Billingsley and Yaychuk, 1986; Gentry and O'Neil, 1984; Munro, 1977; or Harris, 1970).The quantification of risk is important as it provides the necessary yardstick required to allocate the corporation's resources efficiently. Resources are said to be allocated efficiently when the corporation's expected long-term financial reward is maximized while at the same time minimizing its risk (see Hertz, 1968; or Markowitz, 1952 for in depth discussions on efficiency as it relates to investment policy). The efficient allocation of resources should be the objective of any rational corporation. Therefore, rational corporations should employ stochastic evaluation techniques when screening their investments."

Jan 1, 1992