Search Documents

By Fathi Habashi

The year 1987 marked the centennial of the beginning of modern hydrometallurgy. On October 19, 1887 British Patent No. 14174 entitled Process of Obtaining Gold and Silver from Ores was issued*. The discovery was made by John Steward MacArthur (Fig. 1), a chemist-metallurgist, supported and assisted by Robert and William Forrest, two brothers practicing medicine in Glasgow. The discovery was made in the basement of their clinic. The process, which became known as the cyanidation process in reference to the alkali cyanide reagent used, immediately received industrial success in New Zealand in 1889 and in South Africa in 1890t. It displaced the chlorination method which had been in use. In 1903 MacArthur was awarded the first Medal of the Institution of Mining and Metallurgy in London1131 - The cyanidation process was responsible for the doubling of gold production in the world in the two decades which followed its first application (Fig. 2). To the modern metallurgist, it may be surprising to think of MacArthur coming across an obscure reagent such as an alkali cyanide as a leaching agent for gold ores. It is the purpose of this paper to discuss the background and the factors that led to this invention, the development of the understanding of the process, and the application of modern technology.

Jan 1, 1999

By C. Pichler, C. Benigni, J. Antrekowitsch

"The recycling of steel mill dust results in zinc oxides which are sold to the primary industry in or-der to recover zinc in its metallic form. Due to the contained impurities - chlorine and fluorine - these sec-ondary oxides are usually charged into the roaster together with primary concentrates. Appearing problems in this furnace limit the application of secondary materials. Based on the zinc amount, a direct leaching, assumed that a low halide concentration is present, would be possible. To use the zinc solution directly in the electrowinning stage, the concentration of impurities, first of all iron, is limited. Iron can be found in secondary zinc oxides due to carry over during the recycling process. In order to reduce the iron content in the solution, the leaching has to be pH-controlled. This leads to a limited number of simple purification steps before the solution enters the electrolysis. Various trials were performed to evaluate the influence of temperature, time and sulphuric acid concentration on the iron dissolution. This paper deals with the results and also focuses on other impurities such as halides. Additionally, the soda washing process, usually done with secondary zinc oxides to remove most of the halides, and the challenges within this step are discussed.INTRODUCTION Recycling of steel mill dust, which is the main zinc containing residue, in the Waelz process dis-plays the common method worldwide. The product of the process is a secondary zinc oxide which is con-taminated with different elements like lead, iron and halides due to mechanical carry over or evaporation. Depending on the feeding material the concentration of each element in the dust is varying. The zinc con-tent of the product, also called Waelz oxide, lies around 65–68%. Based on these values it presents an al-ternative to the primary concentrate for the production of metallic zinc. The contained halides limit the direct utilization in the leaching stage and therefore have to be reduced. State of the art is a soda washing process but also solvent extraction gives a possibility to remove chlorine and fluorine but the desired con-centration for the electrolysis is hardly reachable (Antrekowitsch et al., 2016) Iron is present as an undesirable component of such secondary zinc oxides due to carry over. During the hot acidic leaching of the secondary concentrate, iron is dissolved too. Based on the higher electrical potential iron has to be removed before the zinc solution enters the electrowinning stage. It is usually removed by precipitation as goethite, hematite or jarosite, which is the common precipitation residue (Ismael et al., 2003)."

Jan 1, 2017

By R. Holmwood, M. Faris, P. Holloway, M. Collins

Sulphuric acid addition is a major driver of the economics in the processing of nickel laterite ores by high pressure acid leaching (HPAL). Understanding the optimal acid addition rate is essential for the success of any HPAL operation, and this is especially true at Ambatovy, where the composition of the feed tends to vary significantly on a day-to-day basis. Most studies on the effect of acid on nickel extraction in HPAL have used laboratory testwork as their basis. Although these studies are invaluable in assessing the economics of a new project, they are limited by the range of ore composition that can be tested and the differences between the operation of the laboratory equipment and the commercial plant. To enable optimization of the acid addition at Ambatovy, operating data from the HPAL operation were obtained using OSISoft’s PI system and the data from several periods were examined to develop relationships between acid addition and nickel extraction. The initial relationships from 2014 focused on the acid required to achieve a target nickel extraction of 95%, with aluminum and magnesium in ore and feed slurry solids content as the major variables. As Ambatovy ramped up through 2015 and 2016, the calculated acid requirement was further refined to address the effects of HPAL temperature and retention time, and the oxidizing/reducing characteristics of the ore, and to generate acid requirement relationships as a function of ranges of nickel extraction. These relationships supported raising the target nickel extraction to 96% and enabled the development of an economic model between acid addition and nickel extraction.

Jan 1, 2017

By B. Tonn, F. Kröger

"The continued development in engine technology is leading to an augmentation in power density which steadily elevates the requirements for thermally and thermo-mechanically highly loaded components such as cylinder heads and pistons. Due to these high performance requirements conventionally applied Al-Si alloys have reached their application limits, since their mechanical properties deteriorate quickly under the influence of heat. Improved applicability is given by Al-Cu-based casting alloys which have a superior high-temperature strength than Al-Si alloys. Since Al-Cu alloys exhibit insufficient casting characteristics, especially regarding hot tearing susceptibility and increased tendency for porosity, it is currently not possible to cast geometrically complex components in robust permanent mold casting processes. The further development of Al-Cu alloys is aimed at finding an optimum between improved castability while high-temperature strength and thermal conductivity are not deteriorated. It is known that a high amount of eutectic reduces the hot tearing susceptibility of an alloy, but it reduces thermal conductivity at the same time. In this paper it will be presented how the conflicting objectives – improved high-temperature strength, good thermal conductivity and reduced hot tearing susceptibility – can be brought together to develop an optimized Al-Cu alloy for application in permanent mold casting.INTRODUCTION At the beginning of the 21st century car, engine blocks were primarily made of gray cast iron (GJL). Less than half a decade later, the choice of material had shifted towards lightweight materials. Ever since, the car engine manufacturing is dominated by aluminum-based alloys. The weight of car engine blocks could thus be reduced by around 50% due to the lower specific weight of aluminum alloys compared to gray cast iron. Furthermore, the high thermal conductivity of aluminum alloys allowed a reduction of complex cooling channel systems and thereby promoted the advancement of this material group. The further development in engine technology leads to an augmentation in power density which elevates the requirements for thermally and thermo-mechanically highly loaded components. For example, in diesel-powered car engines the upper required limits can reach an ignition pressure as high as 230 bar and gas temperatures of up to 1000°C. Thereby, thermal loads can cause high alternating thermal stresses (Grzincic, 2003) which can effectively be reduced by providing high thermal conductivity."

Jan 1, 2017

By Davood Moradkhani, Maryam Rasouli

"The present study reports solvent extraction and separation of zinc from concentrated nickel sulfate solution. In our previous study, Zn and Cd in cold filter cake (CFC, 45-55% Zn, 11-16% Cd, and 2.5-4% Ni) were extracted by alkaline leaching followed by electrowinning processes respectively. The strip solution from electrowinning process, was a pregnant liquor solution (PLS) containing 16.8 g/l Ni and 4.2 g/l Zn. In this work, PLS is subjected to the solvent extraction process for separation of traces of Zn from high grade nickel. The zinc free raffinate containing 16.6 g/l Ni sulfate solution will flow to nickel electrowinning plant for cathode production. Di-(2-ethylhexyl) phosphoric acid (D2EHPA) is the organic phase used in this study. The effects of various parameters such as organic phase concentration (10- 40 % v/v), pH (1.5-3), and temperature (25 and 45°) are investigated. Zinc over nickel separation factor increases by increasing pH from1.5 to 3. The results show that 98.7% of Zn was loaded at25°C O/A ratio of 1, pH 3, and 10% vol. D2EHPA. A 10 M NaOH is used for pH control. However, replacement of pH controlling agent with ammonia solution (25%. v/v) results in interesting observations. Ammonia addition, reduces the solubility of Ni2+ cations in solution. Nickel starts to precipitate from raffinate in a crystalline bluish-green form. The obtained crystals are characterized by XRF and identified to be nickel-bearing analog of boussingaultite, a rare sulfate mineral of nickel with chemical formula of Ni (NH4)2(SO4)2.6H2O. The crystallization rate of crystals is studied. It is a slow precipitation process with 75% in 4 days.INTRODUCTION Annually, many hydrometallurgical processes such as electrowinning, solvent extraction and leaching are applied to waste filter cakes in Zanjan, Iran. These additional processes on filter cakes are critical from both environmental and economic points of view. CFC (cold filter cake) is a toxic but valuable filter cake (45-55% Zn, 11-16% Cd, 2.5-4% Ni, and 0.2-1.5% Cu) produced in many zinc production plants. Our research group at Research and Engineering Company for Non-ferrous Metals (ReCo.), developed a series of hydrometallurgical methods for extraction of zinc, cadmium and nickel from CFC (Moradkhani, & Rasouli 2012). The recovery of zinc and cadmium with alkaline leaching and electrowinning was successfully studied. The strip sulfate solution from cadmium electrowinning unit, contains high concentration of nickel with some traces of zinc impurity. This pregnant liquor solution (PLS) was analyzed and reported to contain 16.8 g/l Ni and 4.2 g/l Zn. In this work, PLS is subjected to the solvent extraction process to separate Zn from nickel (Fig. 1). The organic phase stripping solution containing 4.2 g/l zinc and 200 ppm nickel can be circulated and used in the acidic leaching step. This generates nickel solution with high purity suitable for nickel cathode production."

Jan 1, 2017

By Z. Z. Öztürk, N. Sarica, A. H. Üçisik, C. Bindal

"Titanium oxide films were fabricated on commercially pure titanium surfaces via anodization procedure. Anodization parameters, anodization time and voltage were altered, whereas temperature and chemical composition of anodization bath were kept constant. The main idea in this study is to obtain rough titanium-oxide surfaces. The type and feature of titanium oxide formed were observed via SEM and EDX analyses. What was revealed from SEM and EDX analyses were combined with Ti-O phase diagram in order to make judgment on the type of phases obtained, e.g. solid solution and/or compounds. Studies on the different regions of each sample showed that surfaces consist of different titanium oxide compounds with various O/Ti ratios in nano level and solid solutions varying in terms of chemistry on the same sample. Thus together rough surfaces and inhomogeneous distribution of "titanium oxides" were obtained. It was also found that when anodization time and voltage were increased, more granular surface with higher O/Ti atomic ratio was obtained."

Jan 1, 2015

By John N. Ludden, Maurice Rive, Hillar Pintson

"Quelques soixante-dix-sept plutons présents dans la Sous-Province de Pontiac et dans la partie centrale de la Sous-Province de I’Abitibi ont fait I ’objet d’une reconnaissance systématique. Ils ont été regroupes en huit suites plutoniques majeures et trois suites mineures à partir de critères géologiques et petro logiques. Parmi les suites majeures, quatre représentent I' activité intrusive la plus ancienne dans la région. L’une d' entre e/les est représentée par deux complexes anorthosito-gabbroi' ques lites et les trois autres comprennent les orthogneiss dioritiques a leucotonalitiques et les intrusions dons la composition varie de diurétique et granodioritique à leucotonalitique. Leur mise en place peut être pretectonique a syn ou tarditectonique; certains plutons sont synvolcaniques. Quelques data/ions U! Pb effectuées à propos de ces roches donnent des âges s' étalant entre 2 718 et 2 694 MA. Les données géochimiques indiquent la présence des deux lignées magmatiques, tholemique et calcoalcaline bien qu’il n'y ait aucune évidence de relations entre elles dans I' espace et dans le temps. Ces suites magmatiques différentes peuvent provenir soit d’une croute tholemique impliquée dans un processus de subduction soit directement du manteau.Les trois autres suites majeures comprenant des monzodiorites, des granodiorites et des monzonites ainsi que les deux suites mineures comprenant des syenites correspondent à un évènement intrusif plus jeunesse déroulant entre2 694 et2 680 MA. Ces roches sont syn, tarti a post tectoniques et sont enrichies en alcalins, Ba, Sr et terres rares legeres par rapport aux quatre suites précédentes. Leurs caractères chimiques prop res suggèrent qu' e/les proviennent d' une source différente par rapport à celle precedemment citee.La derniere suite plutonique majeure correspond a un monzogranite leucocrate, riche en pegmatite, également syn a tard tectonique, dont I' age n' est pas connu avec précision. ll représente le seul granite ""vrai"" de la région et dérive d’une anatexie soit des meta sédiments soit des granodiorites-tonalites plus anciennes. La troisième suite plutonique mineure correspond a quatre stocks de granodiorite porphyrique qui n’ont pas été étudiés en détail.ABSTRACTSevenly-sevenplutons have been identified in the east-centra/part of the Abitibi Subprovince and adjacent Pontiac Subprovince. These have been subdivided, on the basis of geological and petrological criteria, into eight major and three minor plutonic suite. Four of the major suite, which represent the oldest intrusive activity in the area, range in composition from dioritic-leucotonalitic orthogneisses to diorite-granodiorite/leucotonalite and include two layered anorthosite- gabbro complexes. Their time of emplacement ranges from pretectonic to syn-late-tectonic and some plutons are synvolcanic. U-Pb zircon ages for these rocks range from 2 718 to 2 694 Ma. Geochemical data indicate the presence of both calc-alkaline and tholeiitic magma series for these rocks although there is no evidence time and space relationships between the two. The different magma series also suggest the derivation of these rocks from two sources, either from subduced tholeiitic crust or directly from the mantle. Three major monzodiorite-granodiorite, monzonite, and two minor syenite suites comprise a younger inlrusive event ranging from 2 694 to 2 680 Ma in age. These rocks are syn-, late- to post-tectonica and, compared to the above four plutonic suites, are enriched in alkalis, Ba, Sr and light Rare Earth Elements.Their distinctive geochemistry suggests that these rocks were derived from a different source region than for the older plutonic suites. The remaining major plutonic suite consists of leucocratic, pegmatite-rich, monzogranite-granodiorite. These rocks are also syn- to late-tectonic but their ages are not known with precision. They are the only ""true"" granites in the area and were derived by the partial melting of either older"

Jan 1, 1990

By David E. Pearson

"There are many tests that can be used to characterize and classify coals, and describe their quality. One of the easier tests, and most versatile in its application, is petrography. Rank and coal type are precisely defined by petrographic evaluation, and in this paper they are compared with other definitions of rank and coal type. Brief descriptions are given of the various rank tests, and of rheological and coking tests used to describe coking-coal quality in Canada. Similarly, tests used to evaluate thermal coal quality are discussed. Finally, the use of these tests as parameters to classify Canadian coals is examined with reference to four coal classifications.Introduction Among all coals there are two independent variables that are required to evaluate coal quality. These are, coal rank and coal type (or composition), and although coal petrography can be used to precisely define them, other methods are often used to provide values that are, in fact, functions of rank and coal type. For example, volatile matter yield is used as a proxy for rank, and free swelling index is used as a proxy for coal type in the International Classification of Hard Coals by type. Currently, there are a number of methods in use in Canada to define rank. The approach taken here, (obviously the author's bias), is that Romax, the mean maximum reflectance of vitrinite, is both a quick and an accurate measure of rank. It is logical to compare the other techniques employed in the measurement of rank to this favoured method. Coal type is, in theory at least, simply a quantitative measure of the various varieties of coal. In practice, the microscopic entities are assigned to a Reactive or Inert category, and at that point objectivity fades from petrography. Despite this somewhat subjective approach, petrographic composition of coals remains an independent variable of such.importance that its place in the evaluation of coal is essential. In this paper, a variety of me.thods that are used to assess rank and coal type are reviewed and compared; the influence of these variables over other parameters that are used to determine the quality of metallurgical and thermal coals is examined, and their usefulness in coal classifications is discussed."

Jan 1, 1985

By S. R. Steinacker, H. Schnideritsch, J. Antrekowitsch

Primary copper industry flue dust plays an increasingly important role in the creation of matte and slag. From a thermodynamic point of view, the chemically formed section of fine particles play a techno-logically interesting role in comparison to the mechanical carry-over. Here, the volatilization and the sub-sequent condensation in the off gas system lead to a characteristic distribution of the contained elements which are represented by various compounds of desired metals like zinc and lead. On the contrary, certain undesired components such as arsenic, bismuth and cadmium accumulate within the product as well. This paper describes existing models and theories concerning the formation of flue dust in the copper smelting process and presents a thorough investigation of the physico-chemical fundamentals by verifying assump-tions with thermodynamic calculations. By fully understanding the formation patterns at different stages and temperatures within the process, better knowledge for flue dust in the first step of the pyrometallurgi-cal copper smelting can be obtained - hence leading to new ideas and incentives for the following stages in the copper production cycle.

Jan 1, 2015

By Mingxia Liu, Hao Li, Qi Liu

"Laboratory batch flotation tests were carried out on fine (-20 µm) hematite to investigate the non-polar oil’s influences when sodium oleate, octyl hydroxamic acid, or oleyl hydroxamic acid were used as a collector. Batch flotation tests were performed with artificial mixed minerals (hematite:quartz = 1:1) under natural pH condition and kerosene was utilized as the model oil. The experimental results showed that kerosene emulsion behaved differently when used in conjunction with the three collectors. Kerosene helped improve the flotation when sodium oleate or oleyl hydroxamic acid was used as a collector. Nevertheless, it reduced concentrate weight yield, grade and recovery to a noticeable extent when octyl hydroxamic acid was used as a collector, especially at low dosages. In addition, single hematite batch flotation kinetics tests coupled with water recovery measurement were carried out to study the role of kerosene at different collector dosages. It was observed that water drainage and the resulting froth destabilization by kerosene was dominant at low collector dosages, especially in the flotation using octyl hydroxamic acid. At higher collector dosages, the water drainage and froth destabilization effect by kerosene was possibly counter-balanced by the higher hematite hydrophobicity and bubble surface tension gradient, which led to more stable froth layer.INTRODUCTION The minerals industry is facing a steady decline in ore grade, compounded by increasing complexity of mineral dissemination. As a result, the ore has to be ground sufficiently fine to have a suitable degree of mineral liberation, which produces large percentages of fine and ultrafine particles outside of optimal size range for ore dressing. Due to the unique characteristics of fine particles, i.e., small mass, high specific surface area, and problems such as increased solubility of complex minerals (Finkelstein, 1997; Finkelstein & Allison, 1976; Fornasiero & Ralston, 2005), high reagent consumption, fast surface oxidation in the case of sulfides (Collins & Read, 1971; Klassen & Mokrousov, 1963), severe particle entrainment (Subrahmanyam & Forssberg, 1988; Warren, 1984), low flotation rates (Glembotsky, 1953; Philippoff, 1952; Ye & Miller, 1988), slime coating (T. K. Mitchell et al., 2005; Parsonage, 1984), etc., flotation performance of these finely ground ores is very poor in terms of low concentrate grade and recovery."

Jan 1, 2017

By S. Kelebek, U. Demir, T. C. H. Richards, E. Koss

"Laboratory-scale tests were carried out to investigate the response of a high-grade (~143 g/tonne) well-liberated gold ore to flotation using two collector types. Octyl and amyl xanthates, representing conventional types of collectors, were tested against an n-octanoic and hexanoic acids under moderate and high redox potential conditions. The latter was based upon a suggestion in literature that monocarboxylic acids are able to adsorb onto the surface of gold at redox potentials near 600 mV (SCE). This investigation did not demonstrate that these carboxylic acids could function as collectors for gold in real ores. In fact, they appear to have slightly depressed gold. However, the results demonstrated that octyl and amyl xanthates acted as highly effective gold collectors for this ore and that an increase in the collector dosage led to an increase in recovery for all mean particle sizes. In some tests, gold recoveries of around 95% were attainable in concentrates with grades around 6 kg/tonne, indicating that xanthate flotation remains a viable means of concentrating gold even at coarse grain sizes. Various aspects of the process such as grade-recovery performance and recovery by size are discussed.INTRODUCTION Three methods are used for the recovery of gold in mineral processing, either alone or in combination: gravity concentration, cyanidation and flotation. Gold occurs as a by-product in some ores together with platinum group metals and as the primary metal in other ores in the form of native gold and electrum, which are alloys of gold, silver and minor amounts of copper. Flotation is a viable method for recovering liberated gold where the gold is visible under an optical microscope (greater than 1 µm in size) and where the attachment of gold grains is not prevented due to bubble loading by competing minerals. It is generally known that grains finer than 150 µm in size will float with most collectors."

Jan 1, 2017

By G. P. Demopoulos

The solubilities of calcium sulfate in HCl-CaC1z-H20 solutions up to 100°C were successfully modelled with the aid of OLI software after bringing proper modification to it. Modelling, more specifically, was carried out with the help of the Environmental Simulation Program, V-6.6.0.4 (www.olisystems.com). New model parameters were obtained by regressing the solubility data. A private databank was established by adding the newly defined model parameters and the calcium sulfate hemihydrate phase that is not included in the original OLI database. The McGill-modified OLI software was successfully applied not only to modelling solubilities but also the transformation of the various CaS04 phases, namely dihydrate, hemihydrate and anhydrite. In this paper, the modelling methodology will be discussed along with a comparison of the capabilities of the newly developed model vs the original OLI model.

Jan 1, 2005

By H. L. Ramandi, P. Moore

"The corrosion of support bolts in underground mines has become an increasingly prevalent issue over the past two decades. With an increase of premature failures due to Stress Corrosion Cracking (SCC), it is evident that understanding the environmental factor influencing the cable bolt corrosion is critical for maintaining effective ground support hence the safety and productivity of underground spaces. Experimental testing of rock and cable bolts were accomplished in a variety of packings, including saturated clay, saturated coal, mine water and grout/cement to investigate their corrosion behaviours. Water samples were obtained and analysed for pH and electrical conductivity (EC) during the experiment. After a period of 76 days the bolts were retrieved and analysed visually. Primary factors were found to be the presence of geological materials and the aeration of the bolts, i.e. the vicinity to air and air flow, while secondary factors were observed to be pH levels and EC. It was also found that the coal/clay interfaces and the water/grout/cement interfaces are non-relevant to corrosion of rockbolts and cable bolts. The proposed framework can be applied to other reinforcement materials used in underground spaces for improved understanding of corrosion environment.INTRODUCTION Rock bolts and cable bolts are the major reinforcement elements used in mining industry to improve the rockmass properties for safe and productive mining. They are normally used to pin large beams or blocks of rock in underground mines to stabilise the rockmass in the roof (strata) against collapse. The rockbolts are typically low cost hot rolled rebar while cable bolts are composed of strands of wire, normally wound together around a central king wire (Hyett and Bawden, 1993; Vandermaat, 2014). The typical length of the bolts in underground mines is 2.4 m and 4–12 m for rockbolts and cable bolts, respectively (Vandermaat, 2014; Windsor and Thompson, 1997). Cable bolts are much more flexible and usually offer a much higher load capacity than rigid rockbolts. Their increased length and flexibility allows cable bolts longer than the height of a roadway to be used in underground mines."

Jan 1, 2017

By R. W. Diamond

Introduction THE Sullivan mine and the milling, smelting, and refining operations of the Consolidated Mining and Smelting Company are sufficiently well known to make unnecessary anything more than a very brief account of the events which led up to this Company's branching out into the chemical industry. This development is the result of the 26 per cent sulphur content of the Sullivan ore. Seventy-five to eighty per cent of this sulphur enters the mill tailing, which is stocked at Kimberley. The remainder, contained in the lead and zinc concentrate, is burned off in the first treatments at Trail. Prior to this new development, the sulphur gas was wasted to the atmosphere. In spire of its great dilution with air and discharge from stacks at high elevations above the plant, some damage to vegetation close to the plant was experienced. It had always been apparent that this sulphur should be recovered and utilized if possible, at the same rime relieving, or curing, the smoke nuisance, and constant studies with this in view had, therefore, been maintained. One of the early conclusions reached was that the Canadian prairies would ultimately require large quantities of phosphate fertilizers, as had been the experience of older countries, and that these fertilizers would constitute a large outlet for sulphuric acid which could be made from smelter gases. This conclusion prompted a widespread search for phosphate rock, particularly in British Columbia and western Alberta, with the result that low-grade beds were discovered in the Crowsnest district and to the north therefrom through extensive areas (1). Following these discoveries, an experimental plant was built at Trail for the production of triple superphosphate in order to facilitate field-tests in fertilizing prairie lands.

Jan 1, 1934

By John Crusius

? 3-year research program overview ? initial results- MainZone pit Waterline pit ? questions raised ? increasingly common in western N. America ? frequently low-pH waters with elevated concentrations of many metals ? water quality controls poorly understood ? some in U.S. are Superfund sites

May 1, 2002

By Han Xing, Cui Jianzhong, Qin Ke, Shao Bo, Zhang Haitao

In this paper, a new approach that uses hot-top DC casting process to producing multi-alloy ingots is present. The different type and size of composite and coated ingots (4045/3004/4045 three-layer composite ingots with section 630mm by 1500mm and 4045/3003 coasted ingot with F140mm/F110mm in diameter) are cast by this approach. The macro-morphologies and microstructures of the composite ingots, the temperature distribution and the element distribution in the interface zone were investigated, also and the interface bonding strength was measured. Results show that the solid supporting layer formed on the cooling plates plays a key role in the casting process of composite ingots. The solid supporting layer can prevent the blending of two melts by resisting the impact of alloy melt, which ensures the stable casting process and casting high quality composite ingots, because the contact height is increased using hot-top DC casting. In addition, fabrication and properties of 4045/3004/4045 three-layer composite ingots with section 630mm by 1500mm are reported in detail.

Jan 1, 2015

By C Carbonneau

In order to successfully produce columbium pyrochlore concentrates, St. Lawrence Columbium and Metals Corporation had to face two principal problems met in several new operations but possibly made more acute than usual owing to the newness of the project. 1.-The ore is particularly complex, as it is made up of an elaborate intermingling of carbonates and discontinuous ultra-alkaline rock bodies of various ages and types in which no less than seventy mineral have been re-ported. Obvious petrographic or structural controls are lacking. Ore boundaries have to be defined on the basis of assay results and the determination of several minerals which occur in trace amounts. 2.-The pyrochlore concentrates produced had to com-ply with a set of stringent specifications. This fact, combined with the low Cb205 content of the ore, necessitated the use of a beneficiation process that would have to operate at a concentration ratio greater than 100:1. A brief description of the mill circuit is given. Mill stability was obtained through extensive mineralogical study of the mill feed coupled with close geological and engineering control of the mining operations.

Jan 1, 1965

By L O. Montpetit

The economics of the asbestos mining industry of Canada, and the physical and chemical characteristics of asbestos fibre, as well as exploration, mining, milling and quality control methods, have been described by several authors in the past few years. The scope of this presentation is to survey the application of asbestos fibres in the major product groups of the construction industry in North America. Principal categories considered include flooring materials, asbestos-cement pipes and building products, high-temperature insulation, textiles, saturated asbestos felts and asphalt com pounds. During 1962, the asbestos mining industry of Canada produced an estimated 1.3 million tons of chrysotile fibre grades, and production capacity is expanding. The market demand for chrysotile fibre, on this continent, has been in the order of 50 per cent of the production volume. The asbestos industry is dependent for growth on the construction industry. Product research is active in finding new uses for asbestos fibre; some of the new developments are presented, including the use of short-fibre asbestos grades for extending the life of asphalt pavement.

Jan 1, 1963

By H. G. Warrington

Abstract As part of the active development programme pursued by Dominion Magnesium Limited since 1945, a modern extrusion plant was erected and has been in operation for about twelve months. The only source of nigh purity magnesium in the world, Canadian metal is produced by metallurgical processes within the frame-work of the mining industry, which gives a different viewpoint to every phase of production from other world suppliers of commercial grade metal whose operations are based on chemical industries and techniques. The superior properties of corrosion resistance and grain refinement have aided a programme of standardization, reducing the number of alloys supplied in extruded form from seven to four as an aid to economic production. The first big step was the development of a general purpose alloy known as AZ?21x covering all decorative and medium stressed applications, which will supersede two older alloys. Sales approaching a million feet in this alloy show that it bids fair to become the 'mild steel' of the magnesium industry, its applications ranging from terrazzo floor strip to textile machinery and television mast components. In the high stressed field, metallurgical features preclude low-cost extrusion of the older high-strength alloys, but recent development of a magnesium alloy containing zirconium promises an easily workable metal. Hitherto produced by expensive chemical additions, research now shows that the alloy can be produced by metallurgical means, which may make this alloy available for a wide range of commercial applications. Thus the future development programme for extruded products in the form of tube, bars, shapes, and structural angles and channels may evolve two alloys to cover all applications for strengths up to 52,000 lb. per sq. in. Such standardization is the result of taking advantage of the physical and metallurgical properties of high-purity magnesium instead of accepting techniques based on metal produced by older processes.

Jan 1, 1951

By Philip Peck

Mine closure issues ?Narrow issues: ?Environmental focus; ?Broad issues: ?Social issues and sustainability; ?Continued importance of mining; ?Historical legacies from closed mines; ?Barriers to development; ?Migration [ir]reversibility Dealing with closure issues ?A matter of choice ?Option 1: Engagein solving closure problems as best possible; ?Option 2: Exit, leaving the playing field to firms not interested in solving problems ?Option 3: Delay, till better time to enter or until early entry [by others] fails and pick property up cheap [?].

May 1, 2006