Search Documents

By R. Pakalnis, H. Miller, Madill. T.

"This paper describes a methodical approach to the estimation of the orientation and the magnitude of in-situ stresses. The study was performed at the Ruttan Mine, Sherritt Gordon Mines Ltd. , a 6,000 T.P.D. underground operation, located in northern Manitoba, Canada. It involves an initial estimate to be made based upon: structural interpretation • virgin stress measurements conducted in other areas (world wide, regional)The verification of the prevailing stress regime was made by conducting CSIRO hollow inclusion(1) overcoring measurements. The current cost for a virgin stress determination is about $7000 per measurement(2) and the difficulty encountered in attaining a good reading is high. This paper will describe the analytical procedures employed at Ruttan in evaluating the in-situ stress magnitude and orientation based on three overcore tests. It is proposed to perform an additional six measurements in order to verify the following results:Vertical stress = av (MPa) = 0.027 by depth (m)Major principal stress = o! """" 2.5 xav (340°/-20°)*Intermediate principal stress = a2 - 1.2xav (070°/0°)Minor principal stress = a3 """" o.8xov (160°/-70°)IntroductionThe Ruttan Mine of Sherritt Gordon Mines Ltd., a 6,000 T.P.D. underground operation, is located in northern Manitoba, Canada (Fig. I). The Ruttan copper-zinc orebody is a multi-lensed, steeply dipping (70 degrees) en-echelon deposit. Individual lenses have a maximum strike length of 350 m with widths varying from 7 m to 61 m. The mining method is o pen stoping with delayed backfilling and extends from surface to 860 m below surface."

Jan 1, 1985

By G. R. Waters

"The technology behind industrial applications such as Hydrometallurgy continues to evolve, as do the corresponding regulations and specifications that ensure the safety of workers and the environment. Valves make up key aspects of this technology, and often represent the single point of failure for entire operations. More often than not, the valves being used in Hydrometallurgy applications are known as Severe Service Valves (SSVs) due to their ability to withstand the extreme conditions. Most experts agree that SSVs are identified by applications, and that these applications are challenging to the valve’s ability to provide a minimum acceptable level of performance over a minimum acceptable duration. The Manufacturers Standardization Society (MSS) of the Valve and Fittings Industry has designated Ross Waters, President of CGIS, as Lead to the Task Force put in place to determine the minimum requirements a valve needs to be able to perform to when faced with extreme conditions, whether from pressure, temperature, toxicity, solids, or usage. This paper serves to determine what the minimum requirements are for SSVs in Hydrometallurgy applications. It will draw on five decades of industry experience from one of Canada’s leading valve experts.INTRODUCTION Severe Service Valves Severe Service Valves (SSVs) mean different things to different people. Until today, defining SSVs had little if any global agreement or recognition. That is about to change as the Manufacturers Standardization Society (MSS) has accepted an application to produce a Standard Practice so defining them. This paper provides information about the selection of SSVs in all industries but focusses on metallurgical processes and applications and offers examples to illustrate the successful and unsuccessful use of these valves. All of this with the purpose of raising the awareness of the industry on all sides, from the suppliers and manufacturers, specifiers and to the users and owners of them. It also supplies tools to understand where and why to separate SSVs from general purpose or commodity valves (GPVs). SSVs are often identified by applications, and these applications are challenging to the valve’s ability to survive. Within these applications the elements that make the service severe are being analyzed, quantified and qualified. From this, we expect to offer objective and repeatable definitions and guidance to improve the experience of SSVs, reduce unnecessary costs, provide longer service life and process runs, improve safety and reduce environmental issues."

Jan 1, 2017

By Fernand Dubuc

"The New Pascalis property is situated in Louvicourt and Pascalis townships, about 200 km east of Val d'Or, Quebec. It is made up of 38 claims under option to SOQUEM since August I, 1981 during which time SOQUEM has earned a 60% interest. The property is underlain by archean basaltic volcanics that have been intruded along the west boundary by the Bourlamaque batholith, and by north -trending dykes.The 1982 disco very is related to the re-evaluation of a 1931-gold showing located in the southeastern part of the property, a combination of the presence of a weak IP anomaly at the eastern end of the showing and overburden stripping at that location, resulted in the discovery of a mineralized diorite dyke.The dyke, which strikes N 20 ° Wand dips vertically , has intruded E-W striking agglomerates. The dyke contains south dipping, gold-hearing quart z-tourmaline-pyrite veins that are distributed in a ladder-type arrangement. Visible gold may he observed in drill core, and is generally associated with pyrite porphyroblasts.Diamond drilling has outlined th e dyke for a strike length of 300 11/ and a width of about 10 m, Result s of this drilling indicate, to a depth of 155 m, reserves of 834 000 metric tonnes grading 8.25 g Au/t un cut or 5.38 g Au/t cut to on e ounce. However, four deeper holes have added depth extension to 400m. Also, west of the dyke and within 150 m, other promising gold values have been intersected within quartz-tourmaline veins associated with other parallel dykes."

Jan 1, 1985

By S. Borle

The microstructural features produced in friction stir welded AZ31, AZ80 and AZ91 alloys are examined when different welding parameters are applied. The microstructures primarily consist of a-Mg grains with a-Mg + Mg17A112 colonies, however melted films of Mg17A112 are produced in AZ91 alloy when high rotation speeds are applied. When the rotation speeds are slow, or the travel speeds are fast the Mg17A112 were incorporated into the stir zone, however they do not exhibit an elongated lamellar morphology associated with melted films. In the case of AZ80, the extruded base material contains a smaller fraction of Mg17A112 and few of these phases are observed in the stir zones. The results are explained based on the dissolution rate and melting temperatures of Mg17A112 controlling the overall morophology and fraction of phases in the stir zone.

Jan 1, 2011

By Fatemeh Saeidi, Luis Marcelo Tavares, Malcolm Powell, Mohsen Yahyaei

"Understanding a single breakage mechanism is fundamental to the development of breakage testing techniques appropriate for mechanistic modelling of any breakage equipment. In the light of this insight, it is also possible to compare any two breakage events in a mechanistic manner. This paper presents a new method to compare breakage mechanisms of two-point impact with compression, different in their applied strain rates. This approach regards a single breakage event as a process affected by three sub-processes; first fracture, capture and spatial distribution of fragments. Spatial distribution is influenced by the kinetic energy of fragments and their brittleness. Using this methodology allows us to examine how each sub-process is influenced by applied strain rate and its impacts on progeny size distribution. For this purpose, two rock types of widely different strength, magnetite and silicate, were tested at various energy levels using the impact and compression mechanisms. To isolate the effect of spatial distribution of fragments, particles were forced to remain in the breakage zone. In this condition, similar progenies were generated from compression and impact mechanisms at similar energy levels. However, allowing natural distribution of fragments, coarser progeny was produced from compression of silicate. Additionally, using this approach provides a physical meaning and explanation for rock strength parameters such as A×b in the t10-Ecs relationship. INTRODUCTIONComminution models are rapidly progressing toward a destination that enables us to explain the complete physics of a breakage process as well as the properties of the ores. Eventually, they will be able to take into consideration the micro-events that take place during the comminution process (Bourgeois and Banini, 2002). Thus, considerable efforts have been made in the last few years in the area of ore breakage characterisation to comprehend and unlock a single breakage process that has been treated as a black box event in the majority of conventional methods. In this paper, an attempt is made to explain the effect of applied strain rate on the breakage properties of rock by using the knowledge that has been gained by understanding a breakage event. This is particularly important due to its application for various comminution devices that operate within a relatively broad range of speed."

Jan 1, 2016

By P. Groleau, O. Tavchandjian, D. Marcotte

In open pit mining, each small mining unit (SMU) is selected for mill processing based on an estimate of its true grade. The estimation is usually done using analyses of cuttings from blast holes within that SMU. One common estimator used for selection is the arithmetic average of within-SMU samples. This estimator is conditionally biased. The effect of a conditional bias is to overestimate the profit really recovered from the deposit. For this reason, a conditionally unbiased estimator is preferable. Increasing the number of samples generally improves the accuracy of the estimation (and diminishes the conditional bias, if present, of most estimators). However, there exists a practical limit where an additional sample does not improve the estimation sufficiently to cover the expense of making the analysis. This limit is specific to each deposit and depends on geostatistical parameters, economic factors, and mining parameters. This study examines how the number of samples affects the recovered reserves and the resulting profit. Also, the effects on optimal profit of varying the different factors are examined. Globally, the number of samples required increases with the selectivity of the operation. For a given ore deposit, the greater the number of SMUs selected for processing, the fewer samples are required and vice-versa.

Jan 1, 1998

By W. J. Przybylowicz, V. M. Prozesky, D. de Bruin

"The common style of gold mineralization in the Basal Reef and other auriferous conglomerates of the Witwatersrand Supergroup comprises clusters of gold grains occurring interstitially to quartz and pyrite pebbles as well as gold accumulations attached to the surface of and infilling hairline cracks and fractures in round, compact, detrital pyrite. The latter textural association is generally interpreted as a result of remobilization of originally detrital gold during regional metamorphism and related hydrothermal fluid circulation. There is general agreement that, although gold solubility was low, ore modification occurred during the metahydrothermal event, but uncertainty exists about the magnitude and scale of gold remobilization.Micro-textural and chemical investigation of compact round pyrite and associated gold accumulation has established that gold is preferentially deposited on chemically heterogeneous pyrite surfaces. Combinations of alternating high- and low-As zones in pyrite result in mixed np-type conductivity accompanied by electron exchange and the reduction-driven deposition of gold at the cathode. This model does not explain gold accumulations which are not immediately linked to chemical heterogeneities and it is inferred that an additional control on the deposition of gold was exerted by physical defects which lead to zones of increased charge density and/or areas of focussed conductivity. The inferred precipitation mechanisms suggest that submicrocopic physical and chemical controls are the important factors that determined the sites of gold nucleation and that precipitation mechanisms based on physicochemical changes of the hydrothermal system were not involved. The Basal Reef contains on average close to 5OJo of round, detrital, chemically zoned pyrite which provides a large number of electrochemically active pyrite surfaces. The extremely effective electrochemical precipi- . tation mechanism together with the low solubility of gold in Witwatersrand fluids is the main reason for the spatially restricted remobilization of gold in the conglomerate reefs."

Jan 1, 1994

By Laurier Juteau

"NOT TOO LONG AGO, the CIM Education Committee saw the need for an information campaign to promote interest in mineral industry careers among young people. Today, times have changed and the Committee has now placed emphasis on the definition and function of the mining engineer. This situation, we believe, is entirely normal and the change of emphasis is not due to a change in the needs of the industry but more to a diversification of these needs. In years past, the Canadian mineral industry, although a very important part of our economy, was looked upon as a specialized craft and, because of the richness of our resources, did not suffer too much from competition. Now, times have changed and we are increasingly at the mercy of the competition and damaging inroads of price fluctuations, etc. We will therefore answer the questions raised in this discussion in the light of the role played in the past and the role to be played in the future by the Canadian mining engineer. We will begin with the following premises : (a) If mining engineers are to be involved in the massive problems of society, their traditional background is not sufficient. (b) Councils for professional development are working on criteria for the accreditation of advanced degree programs in the United States as well as in Canada, and, simultaneously, three-year technology programs are being developed along with professional engineering degree programs. (c) The difference between European and American industries regarding philosophy of life is that in Europe they appreciate wisdom more than HPs while in America the HP seems to be more important. The Engineering Digest of February 1972 reported that in the United States, during June and July of 1971, the second highest rate of unemployment was for the 55 to 64 age group ( 4.1 per cent). This survey certainly applies to Canadian industry as well. (d) Degrees to be awarded in Canadian universities and technical schools in 1972 will be:"

Jan 1, 1972

By Philip M. J. Gray

"The real cost of conversion from ore to semi-fabricated non-ferrous metals has been increasing for many years. Consumer resistance and improved knowledge and techniques now available justify investment in revolutionary as well as evolutionary methods of extraction. Metallurgical factors in current practice which preordain high production costs are identified as: smelters' demand for clean minerals, use of processes with low intensity of working per unit of reactor volume, use of low-velocity reactions, use of long reactor retention times relative to the speed of reactions, dilution of values in solution and commitment to electric power as a source of energy.Six new types of flowsheet are proposed for processing from ore to metal, composed of steps which are economic to construct and maintain and making maximum direct use of fossil fuel and the energy content of minerals. The basic knowledge and technology for developing these flowsheets exists. It is very tentatively suggested that these routes might reduce the capital and production cost for conversion of ore to metal by 30-50%."

Jan 1, 1980

By R. W. Thompkins

"PREFACEPart 1 of this paper, published in the September issue, covered the occurrence of uranium, radiation from uranium ores, the uranium series, radioactive theory, radioactive equilibrium and application to the radon series, the working level, the theory of emanation and diffusion, transport by thermal diffusion of radon emanating from porous rocks, and definitions.The October issue carried Part 2, which dealt with radiation theory applied to uranium ores, other radon migration factors, factors affecting the radon gas release rate, the measurement of radon gas emanation rates, the tunnel concept, variation of emanation rate with grade and estimating radioactivity from grade analysis.Part 3, in this issue, concludes the series by discussing the techniques for controlling radiation and providing some example calculations.17.0. Techniques for Controlling Radiation17.1. Altering the Factors In the Diffusion EquationIt has been noted that radon gas emanates from the surfaces of exposed ore to the mine atmosphere. The diffusion laws establish the rate of this flow. The fundamental relationship is that the rate of flow (J) is a function of the pore concentration and the distance from the surface. It is expressed as: []If any of these terms is varied, either naturally or artificially, the rate of gas emanation will be altered.Altering the Diffusion CoefficientThe literature describes many ways to lower the radon gas emanation rates which are dependent on changing the diffusion coefficient:1. A layer of ice on top of a tailings dam or on a soil.2. Humid clayey materials and swamped soils over a radon source."

Jan 1, 1982

By Fazel G. Jahromi, Ahmad Ghahreman

"Several studies were performed on the atmospheric leaching of copper sulfide minerals in the presence of activated carbon and a new catalyst, AF 5. AF 5 is a carbon based catalyst with similar properties to those of activated carbon however much better mechanical properties. The activated carbon surface chemistry has been investigated in various studies; however the connection of the surface chemistry of activated carbon and AF 5 with the sulfide minerals during the atmospheric leaching process is not well-understood yet. Based on the surface analysis, AF 5 showed higher surface area than activated carbon (AC). Adsorption and oxidation of copper, arsenic and iron ions in the presence of different activated carbon were investigated. Adsorption properties of both catalysts were similar and 18-24% of iron, 12-18% of copper and 10% of arsenic adsorbed on the catalysts surface form 5 g/L Fe(III) and Cu(II) and 2 g/L As(III) at 80°C. In oxidation experiments, both catalysts reduced Fe(III) and Cu(II) ions and re-oxidized the reduced species in the presence of oxygen and oxidized As(III) ions. The addition of oxidizing ions can enhance the oxidation process kinetics and increase the catalytic capability of carbon.INTRODUCTION Hydrometallurgical processes of copper sulfide concentrates are under development and various different methods have been proposed to increase the atmospheric leaching rate of copper sulfide minerals. These methods include using different media, reagents, and catalysts. Among different methods, leaching of the copper sulfide minerals in the chloride media has some advantages over sulfate media. Smaller scale of operation, increased leaching rates, and lower sulfate formation are some of the benefits of the chloride leaching media over other similar media. Moreover, using ferric and cupric ions as oxidants and utilizing activated carbon as a catalyst has been proven to enhance the leaching rate of copper sulfide minerals effectively. Activated carbon (AC) and AF 5 (micro porous carbon based catalyst) are two of the most efficient and practical catalysts in copper sulfide leaching processes. AC can enhance the copper recovery of enargite in chloride media from 69% to 92% after 96 hours of leaching under the similar conditions (Jahromi & Ghahreman, 2016). It has been shown that AC at acidic pH can generate hydrogen peroxide in the presence of oxygen which can leach copper minerals (Ahmumada et al., 2002)."

Jan 1, 2017

By Victor Rudenno

"Previous methods have employed statistical analysis to model future mineral resources. The method presented in this paper uses Zipj's Law to determine the size and grade of tin deposits still to be discovered. The law is applied independently to both known deposit tonnage and grades. A probability distribution for both 'tonnage and grade is computed/or those deposits still to be located and then, by applying a correlation between tonnage and grade, a distribution of the probability of metal content discovery is obtained.By considering an economic cut-off in metal contained in a deposit, the probability of economic success for the next tin discovery is computed, both for a world discovery and for the special case of Tasmania, Australia. The results indicate a probability of 11-37% on a world-wide basis and 18% chance of economic success in Tasmania.IntroductionIn the past , most attempts to determine the probability of success in finding an economic mineral deposit have relied on the accumulation of statistical data. These data are then used to predict a suitable frequency distribution to assess the probability of finding a deposit of a given size and grade (Singer,1975).The method not only relies on one having sufficient data, but also on the assumption that the data are not biased and that the distribution (usually log-normal) is a correct one. The method presented in this paper, to analyze tin deposits, uses Zipf's Law, which has been recently applied to oil, uranium, lead-zinc and gold deposits by Folinsbee (1977) and to Western Australian gold deposits by Rowlands and Sampey (1977). Tapp and Koniuszko (1978) have applied Zipf's Law to mineral distribution patterns in the Northern Australian orogenic provinces, which has enabled them to make predictions with a relatively small data source."

Jan 1, 1981

By David Christensen

The long-term performance of dry covers is being examined in a research study funded by the International Network for Acid Prevention (INAP). The study was separated into two phases. The two main components of Phase 1 of the study were the identification and research of the processes affecting the long-term performance of dry cover systems and an examination of available numerical models for simulation of long-term cover performance. Identification and research of the physical, chemical, and biological processes affecting long-term performance showed that cover performance could be related to the change in the saturated hydraulic conductivity of cover material, the change in the soil-water characteristic curve, and the physical integrity of the cover system. Seven numerical models were examined to evaluate their effectiveness in predicting the long-term performance of cover systems. VADOSE/W (Online Help v1.01, 2002) was selected for use in cover system modeling in Phase 2 of the project. Phase 2 of the research study is currently in progress and involved the selection of five mine sites with a minimum of three years of performance monitoring data for analysis of cover performance. Two of the mine sites will be analyzed with the two-dimensional VADOSE/W numerical model. In addition, field saturated hydraulic conductivity tests were completed at three mine sites to investigate the change in field hydraulic conductivity of the cover system materials. The objective of the field testing program was to evaluate changes in hydraulic conductivity of cover material with time. Measurements of field hydraulic conductivity were completed with a Guelph permeameter and a pressure infiltrometer at three sites. The field hydraulic conductivity data was used to evaluate whether a change in this key material property had occurred over time. Field observations and the historic performance monitoring data provided the necessary information to develop hypotheses as to the likely processes that led to any change in field hydraulic conductivity. This paper will briefly summarize the research completed in Phase 1. The remainder of the paper will focus on the field testing program completed to measure the field hydraulic conductivity of constructed cover systems.

Nov 1, 2002

By Richard Dawson

Presentation Outline? Northeast BC Coal Fields Overview and History ?New mines and projects in development ?Design Issues for steeply dipping footwall slopes ?Design issues for angle-of-repose waste rock dumps

May 1, 2006

By Afshin Sadri, Wai Lai Ying, Brycklin Wilson, Zoe Coull

"Although there have been great steps forward to integrate corrosion engineering into operations, there is still an underlying tendency for maintenance tasks to be performed in a reactive manner. This is especially true when strategies focus on lagging indicators such as visual inspections, RCA (root-cause analysis), and FMECA (failure mode, effects and criticality analysis). This trend to “reactive maintenance” can be avoided by utilizing more inspection and monitoring methods to identify leading indicators of failures. Prevention is generally less costly than repairs; moreover, when paired with appropriate monitoring techniques, intervention of corrosion protection can be more effectively timed and based on more accurate data. Hatch asset reliability studies show nearly 80% of defects are introduced through operations and maintenance. Therefore, proactive corrosion management can provide the necessary feedback to optimize operations and maintenance strategies preventing costly corrosion losses. Understanding corrosion risks gives a clear picture of the benefits of a proactive approach to asset performance. Monitoring techniques (Non-Destructive Testing, field testing, sampling, etc.) by nature are a more effective means of improving maintenance efforts and preventing corrosion losses than other methods (RCA, FMECA). This paper will outline the importance of proactive corrosion management and demonstrate its benefits through industry examples.INTRODUCTION Over the past few decades, with the growth of technology and awareness of sustainable development many studies have shown the benefits of a proactive approach to maintenance strategies. However, in practice there is still an underlying tendency for maintenance tasks to be performed in a “reactive manner”. This is especially true when strategies focus on lagging indicators such as visual inspections, RCA (root-cause analysis), and FMECA (failure mode, effects and criticality analysis). This trend to “reactive maintenance” can be avoided by utilizing more inspection and monitoring methods to identify defects and leading indicators to failures."

Jan 1, 2017

By F. R. Erick Mulder

"AbstractTwo bottom-hole samples have been taken from two new completions in the Turner Valley field, Royalite Lowery No. 8 on the west flank and Royalite No. 73, which was deepened into a lower fault block, on the northeast flank. From the bottom-hole oil of Royalite Lowary No. 8 a synthetic sample was prepared to simulate the original fluid in the reservoir, saturated at the gas-oil contact conditions. The sample from Royalite Lewery No. 8 has been shown to be the original fluid present at this well and represents the oil phase near the oil-water contact in• the reservoir. Complete chemical analysis, P.V.T., and viscosity data have been obtained on these reservoir fluids, which represent the range of saturation from the gas-oil to the oil-water contact in the Turner Valley oil structures. Sampling techniques and the application of the analytical data to reservoir conditions and field operations are discussed. Super-compressibility curves for an average separator tail gas have also been prepared. These data have not been available before. They will be of fundamental value in futu.re reservoir engineering studies of this field and will also serve as a guide in determining operating practices."

Jan 1, 1950

By Zihe Ren, Edouard Asselin, Marcus Tomlinson, Tianbi Zhang, Jing Liu

"Raman spectroscopy is used to quantify the extent of disorder in the carbonaceous matter associated with preg-robbing ores. Previous studies of Goldstrike ores showed that the height and width of the peaks for the “D” (disordered) and “G” (graphite) bands, the so-called “Raman ratio” had a strong correlation to the preg-robbing value (PRV) measured for various ore samples. A brief literature review on Raman spectroscopy as it applies to preg-robbing ores is presented. Further, recent studies, presented here, have shown no correlation between the Raman ratio and the PRV for a wide variety of ores. This suggests that the extent of organic carbon crystal disorder is not the main factor in determining preg-robbing characteristics.INTRODUCTION Preg-robbing may arise from natural carbonaceous materials in the ore. Several mechanisms have been proposed in the past decades including a physical sorption process by the carbonaceous matter, or via the reduction of aurocyanide at the mineral surface (Abotsi & Osseoasare, 1986; Afenya, Osseoasare, & Abotsi, 1983; Tan, Feng, Lukey, & Van Deventer, 2005). Nevertheless, the mechanisms of preg-robbing remain poorly understood. Understanding the nature of the preg-robber is of practical importance for the selection of a suitable treatment process. Fine carbon particles in the ore have been recognized as preg-robbers due to their similarity to the activated carbon used in the carbon in leach (CIL) or carbon in pulp (CIP) processes. Previous research has illustrated that the activated carbon (also referred to as amorphous carbon in some literature) has a much higher absorption ability than pure graphite with high crystallinity (Adams & Burger, 1998). Adams et al (Adams, Swaney, Friedl & Wagner 1996) concluded that carbonaceous matter is largely responsible for the overall preg-robbing capacity of a given ore. However, the mechanism of carbon preg-robbing was still not clear mostly due to the complexity of amorphous carbon and its behavior in different solution matrices, and at different pH and temperature (Adams, 1990, 1993)."

Jan 1, 2017

By C. F. Gleeson

"I HAVE BEEN ASSIGNED the pleasant task of adding a last word in way of summary to this session. I think that the trend set in having a geochemical session at the CIM Annual General Meeting is a good one and I hope it will continue so that members of the mining fraternity can get together on a regular basis and discuss geochemical problems peculiar to our Canadian scene. A series of interesting papers have been presented on what has been considered by many in the past as not only a problem area for geochemistry but even an impossible one. The papers should help dispel some of these fears. Lack of development of geochemical techniques in the Shield has been due to a variety of factors, many of which have been mentioned. However, I feel that one of the main reasons for this lack of development has been timidness on behalf of many people to get out and do the necessary work which helps produce answers to many of the questions asked. New developments and applications of geochemical methods in the Shield will not be done by the faint of heart but by those who have the curiosity, interest, imagination, drive, resources and, most of all, the intestinal fortitude to stick to it and not give up because results or conditions do not meet with preconceived notions. Another element that will be needed by those who will successfully apply the techniques and who will be responsible for new breakthroughs is the systematic approach to sampling and analysis and the integration of geochemical, geological and geophysical results. Erratic sampling patterns - a sample here and a sample there - generally lead to more problems than solutions."

Jan 1, 1971

By J. W. Smith, J. G. Eacott, D. H. Napier

"Three hydrometallurgicat processes (Noranda chloride leach, B. C. Research biological leach and Sherritt-Cominco activated oxygen leach) and the Noranda pyrometallurgical process have served as the basis for design projects in the final year of the chemical engineering program at the University of Toronto. Each member of a team of five or six students devotes about 200 hours to the project and the final report is expected to include an economic analysis.None of the processes has been developed to full- scale plant, nor, in the case of the B.C. Research and Noranda processes, were pilot plant data available. Nevertheless, the designs developed provide a useful basis for a preliminary estimate of capital and operating costs and for a preliminary assessment of project feasibility.This paper discusses the approach used in the design projects with respect to engineering and economic aspects, and outlines the educational features and benefits of such a program as well as some of the problem areas that arise.IntroductionAs part of the undergraduate degree course in chemical engineering at the University of Toronto, students devote some 200 hours to a design project in their final year. Hydrometallurgical processes, not yet proven at the commercial scale, have been selected for study. The students are required to develop laboratory and / or pilot scale results into a conceptual plant design, using sound engineering principles. Capital and operating costs are then determined and a preliminary feasibility study and economic analysis are carried out."

Jan 1, 1986

By G. Morin, G. Marin, M. C. Parr, J. Carignan

"Investment casting offers many advantages for the near net shape production of complex geometries, however, molten titanium reacts with most of the refractories used in investment casting shelling systems, which leads to the formation of an oxygen contaminated surface layer. This layer, called alpha case, is 0.1 to 0.6 millimeters in thickness according to the casting section size and must be removed either by mechanical or chemical milling processes. Alpha case removal processes affect casting tolerances and may contaminate the part intended for medical applications (e.g. embedding of abrasive grit media in the alloy). A shelling system based on an yttria prime slurry has been developed and was found to almost suppress the mold metal reaction. Yttria is an expensive refractory, but slurry life was found acceptable for small castings using a closed container and flow coating process instead of conventional pattern dipping. Alpha case depth has been determined for Ti6Al4V by metallographic techniques and microhardness measurements on different step block casting cross sections. Alumina and yttria second prime stuccos were evaluated in this study. The shelling system minimizes finishing operations in the production of casting for medical applications.INTRODUCTIONTitanium investment castings have been in the commercial market since the beginning of the titanium era in the mid 50’s. Investment casting is a cost effective way to produce complex parts for medical, aerospace and chemical processes applications. Investment casting of titanium is difficult due to the high reactivity of titanium with air and refractories used for shell mold building especially for the face coat. Melting is done under vacuum and no shelling system has been proven effective to suppress the mold-metal reaction yet. The main issue with the mold-metal reaction is the formation of an oxygen enriched zone at the surface of the castings named alpha case (Frueh et al., 1997; Kim, 2002; Saha, 1986). The alpha case is brittle, reduce the fatigue life in service of the parts and must be removed by chemical milling.For industrial purposes, calcia partially stabilized zirconia based slurries have become widely used in titanium investment casting for primary coats due to a combination of limited metal shell reaction. Calcia stabilized zirconia slurries have an acceptable shelf life and offer an interesting production window. Our experience shows that a resulting alpha case depth is 280 micrometers for a casting section of 6.35 mm in thickness is typical with such a shelling system (Morin, 2013)."

Jan 1, 2016