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By W. R. Tyson

IT HAS BEEN KNOWN for many years that alloy steels can become brittle when tempered in the range of 350-600°C, or cooled slowly after heating to higher temperatures. The metallurgical literature reveals that blacksmiths were aware as early as 1883 that water quenching was necessary after heat treatment above 600°C to avoid brittleness. It has also been known for years that the problem is associated with trace impurities; a paper in the Journal of the Iron and Steel Institute of 1894 refers to the brittle, faceted fractures that occur in steels containing arsenic, phosphorus or sulphur. However, definitive investigation of the mechanism of embrittlement has been possible only within the last decade with the introduction of new experimental techniques to investigate surfaces, especially Auger electron spectroscopy. It is now possible to study in detail the chemistry of surfaces with a resolution of an atomic layer or two, and enormous progress has been made recently in studying the segregation of impurities to grain boundaries by exposing the boundaries by fracture inside the microscope. A clear picture of the processes occurring and their interpretation is now emerging, as was particularly clear at the recent 1977 ASM Materials Science Seminar on Interfacial Segregation held in Chicago in October. Recent research in this area has pointed the way for commercial exploitation of this new knowledge and experimental technology. It is the purpose of this article to trace progress in understanding temper embrittlement and to indicate other areas where control of interfacial segregation and its effects can be important in metallurgical applications.

Jan 1, 1978

By Vard H. Johnson

"In contrast with the well-publicized Pittsburgh coal, and the Everglades of Florida, most coal-forming swamps of Cretaceous time in western North America occupied relatively limited areas. They formed in areas of irregular subsidence, bounded by the changing levee systems of meandering streams. Coke quality is determined by the physical and chemical behaviour of the vitrain during thermal decomposition. Vitrain is at least in part a colloidal substance, originally containing large proportions of water; its formation and survival depend on maintaining a shallow cover of stagnant water up to the time of burial. Heat from swamp fires or subaerial dyhydration could destroy it or impair its quality. Observed patterns suggest that the metamorphism is almost entirely thermal, and that there is little relation to tectonic stresses, or loading. These coals had probably achieved essentially their present rank prior to deformation. Evidence of frictional heating along the thrust planes is minimal or absent. Normally, coal beds are aquifers. Oxygen carried into the subsurface becomes available and reacts with the vitrain to destroy its natural thermoplastic properties. The tolerance of oxygen without loss of thermoplasticity is inversely related to the volatile content. Significant lateral variations of coal thickness are common and sometimes occur in short distances. In deformed areas these thickness changes are more commonly due to differential tectonic stress rather than to original thicknesses of coal. Locally, coal is known to have flowed into cavities, or fractures. These principals are discussed in relation to coal deposits of western Alberta and eastern British Columbia."

Jan 1, 1972

By R. E. MacAfee

THERE have been great changes in the design, capacity, and pressure of steam generating units over the past fifty years. If we go back as far as 1890, the plants then existing were largely horizontal return tubular boilers, hand-fired, with the boilers supported on the brick sitting which was com-posed of red brick with, probably, a refractory lining one brick thick in the combustion chamber. About this time, the water tube boiler began to supplant the H.R.T. boiler and, where new plants were being constructed of any size, water tube boilers were largely installed. In those days, say from 1890 to 1905, a 250 h. p. water tube boiler was considered a large unit. These boilers were largely the straight tube type and were set with the first row of boiler tubes three to six feet above the grates. The brick setting was a combination of red brick and fire-brick. The fire-brick lining in the furnace proper was usually 9 in. thick and in the first pass 4 1/2 in., while the rest of the setting was entirely red brick. These units were largely hand-fired and were expected to produce about 100 per cent rating as a maximum. It may be well at this point to define rating, which is the evaporation of one boiler horse power per hour by each ten square feet of heating surface in the boiler. A boiler horse power is the evaporation of 34.5 pounds of steam from and at 212°F. Consequently, a boiler containing 2,000 square feet of heating surface is rated at 200 h. p. and the evaporation at 100 per cent rating is 200 X 34.5, which equals 6,900 pounds of steam per hour from and at 212°F.

Jan 1, 1939

By C. Lambert

It has been shown that contacts between host rock and engineered barriers may be critical in the design of deep radioactive waste repositories. Water is expected to reach the interface zone after the re-saturation of the geological massive and its presence may lead to concrete leaching. Such a phenomenon could increase the interface transmissivity and compromise the confinement of radioactive waste. Recent experimental results from Buzzi et al. (2008) have enhanced how concrete leaching can drastically change the mechanical behaviour of such interfaces. Because of the local loss of strength resulting from leaching, shearing resulted in a degradation of the interface asperities. Similarly to rock joints, intact interfaces exhibit a usual contracting-dilating behaviour. On the contrary, depending on the extent of leaching, the degraded interface can display a fully contracting. This paper intends to investigate the influence of concrete leaching on the mechanical behaviour of host rock-concrete interfaces. The leaching process consists in the dissolution of some of the hydrates of the cement paste, leading to a reduction of the strength and Young's modulus. A discrete model has been developed with PFC3D where a simplified interface morphology has been introduced using a saw-tooth description of the asperities.

May 1, 2009

By V. A. Leão, A. M. Silva, S. M. Bertolino, B. C. S. Ferreira, D. Guimarães

Although not considered a high risk pollutant as compared to toxic metals and acidity, environmental agencies worldwide are proposing regulations to control sulphate in effluents and drainages by setting a threshold value varying between 250 mg/L and 500 mg/L. The aim of this study was thus to compare four different techniques for removing sulphate ions from mining/metallurgy effluents. The first alternative studied was sulphate removal by precipitation as ettringite. Treating a synthetic solution containing 1650 mg/L sulphate at 22±1 ºC resulted in removals close to 85% during continuous precipitation. Sulphate sorption was also investigated using three different ion exchange resins as well as limestone. Fixed bed experiments produced sulphate loadings of up to 70 mg SO4 2-/L resin, at pH 2.0. In neutral wastewaters, limestone is also a potential adsorbent producing a maximum particle loading of 19 mg/g. Sulphate sorption on limestone seems to be an alternative to treating mine waters with sulphate concentrations below the 1200-2000 mg/L range, where lime precipitation is not effective. Subsequently, sulphate removal by sulphate reducing bacteria was also investigated and it was observed that reactor’s hydrodynamic conditions and the choice of substrate are important factors for the process. The different technical aspects of each technology are addressed.

Jan 1, 2014

By P. Condori

Palabora Mining Copper (PMC) has two autogenous mills that have been in operation since 1976. The mills were originally designed to treat 30 000 t/d of open cast copper ore in a closed circuit with cyclones. As the ore body went deeper the open cast method of mining was changed to block caving, a consequence of this was the dolerite content (hardest barren material) increased significantly, increasing the production rate of pebbles and thus reducing the milling capacity. In order to cope with the increased ore hardness and to increase mill capacity, a second ball milling stage and pebble crushing were incorporated to the circuit. The above actions created new challenges to the circuit operation and bottlenecks in different areas of the milling circuit. This paper reports the holistic work performed on the Palabora autogenous milling circuit including the implementation of a mill constraint control scheme, the implementation of a pebble removal system from the circuit and a new circuit configuration. The achieved plant stability and increment of ore throughput are also reported in this paper.

Jan 1, 2012

By Chi Zhang, Junyi Wu

"The use of permanent stainless steel cathodes for electrorefining and electrowinning of cathode copper had been introduced to the market long time ago and now is a well-accepted technology worldwide. During the last decades, the Chinese copper refinery industry had been growing rapidly and many large scaled production plants had been built. In the modern refineries, permanent stainless steel cathodes are introduced and used instead of traditional starter sheets. The most common steel grade used is austenitic stainless steel S31603 (316L/1.4404), while both S30403 (304L/1.4404) and N08904 (904L/1.4539) have been used depending on the actual working conditions, especially with regarding corrosion environment. While 316L permanent cathode functions well in many plants, different kind of problems, such corrosion and deformation, have been reported. There is therefore an increased need for more suitable material. New stainless steels, such as duplex stainless steels, with better properties have been tried and introduced into the application of permanent stainless steel cathode with satisfied results. The article introduces first the Chinese copper refinery industry and properties of duplex stainless steel in general, and then describes the development of using permanent duplex stainless steel cathode, including the actual working conditions, production of cathode sheets as well as the experiences of application in details. After more than one year’s usage, the advantages of permanent duplex stainless steel cathodes are clear seen.INTRODUCTIONChina has become a major player in the international copper market, accounting for around 40 percent of global refined copper demand. Despite the slowdown of the Chinese economy, the consumption of copper products will still increase, but with a medium and/or low growth which will be the new situation for the coming years. The average growth rate is expected to be around 5 percent per annual. In the coming Five-Year plan for National Economic and Social Development a number of initiatives will be finalized which will require massive amounts of copper. In 2015, the expected consumption of copper products will be over 9 million metric tons. The main driver of the consumption is the electric power industry which accounts nearly the half of the total consumption; followed by cooling application with 15% and transportation with nearly 10%, see figure 1."

Jan 1, 2016

By J. F. Davis

Pegmatite dykes containing lithium minerals and beryl occur dose to the borders of intrusive masses of granitic rock in the Winnipeg River area of Manitoba. Both vertical and flat-lying dykes are present. Most of the pegmatites consist of zones, containing characteristic mineral assemblages, arranged more or Jess parallel to the borders of the dykes. Five important lithium minerals are present; each occurs in a separate zone, but all the lithium-bearing zones are situated toward the centres of the pegmatites. Spodumene is the most abundant and widespread of the lithium minerals and occurs as small crystals intimately intergrown with quartz. Beryl is not an important constituent of the lithium pegmatites, but when .present, occurs outside the lithium zones, toward the margins of the -dykes. Beryl is most common in dykes containing few or no lithium minerals. The mineral assemblage in the beryl zone of the lithium dykes is the same as that of the beryl dykes. The attitude and internal structure, particularly zoning, of the pegmatite dykes, and the texture and assemblages of the constituent minerals, have an important bearing on exploration, development, and mining of these pegmatites, and on the extraction of various mineral products from them.

Jan 1, 1958

At the end of a century of mining education in South Africa, it is appropriate to reflect on the past, take stock of the present and ponder the future of mining education. While it is likely that changes in the mining industry will generate an increased demand for mining graduates, the number of suitably qualified applicants to study mining is worryingly small. While good progress has been made in unifying the educational system that previously provided schooling on a racially separate basis, it appears that a decade or more will be required to raise competency levels in mathematics, science and English, and this paper describes the process as it affects mining engineering programs. It also describes the initiatives currently being undertaken by the University of the Witwatersrand and the mining industry to ensure that the South African industry receives an adequate flow of well-qualified mining graduates, despite more than 70% of the intake coming from severely disadvantaged educational backgrounds.

Jan 1, 1999

By Chris Twigge-Molecey

Demand for metals will continue to grow as global population numbers and prosperity levels steadily increase. Consequently, there will continue to be a need to design and construct new metallurgical plants. Business success in general requires projects to be financially successful and return appropriate value to their owners. However, in the metals industry, private and public sector financing sources have become very sensitive to the perceived inability of projects to contain costs and meet other business objectives. Thus, the capital for projects has become more difficult and expensive to obtain. It is instructive to note that Ernst and Young (2011) identified that: “Delivery of predictable project results bestows competitive advantage and market confidence to those corporations who successfully instill this discipline”. The implication for future projects is that they must be systematically developed to minimize perceived risks—and more importantly—to demonstrate that the risks are managed to achieve the business case. Then, provided that the project has been developed in a well-structured way, project success can again be defined as a project with: a final cost within 10% of the budget approved at the end of FEL3, when the project is properly defined and the permit conditions are agreed upon; a start-up date within three months of the definitive, scheduled startup date; production levels at 85% of design capacity within a year of starting commercial operation; production meeting the target environmental restrictions; and with zero lost time accidents during construction and startup. The plant design is one of many integrated activities required to achieve these objectives. This book represents a valuable link between the existing engineering literature that encompasses a wide range of engineering fundamental textbooks and design manuals and the project management literature such as the Project Management Body of Knowledge, or PMBOK® (Project Management Institute, 2014). It is evident throughout this book, that the design team is a small but essential part of a much larger project team comprising the project management, construction management, and construction contractor staff. Design activities must be regarded and managed as part of the integrated whole, with two fundamental links throughout the design process:

Jan 1, 2015

By David L. Anderson

This paper explores the financial impact of the initial version of the Saskatchewan Potash Reserve Tax; first, a one; and second, in conjunction with the other taxes affecting the industry's profitability. A though the introduction of the Reserve Tax is shown to lead to a substantia increase in a hypothetical firm's effective tax burden, the more unusual outcomes frequently attributed to this levy on y occur after the imposition of other non-provincial tax rulings. Despite this qualification, the results obtained suggest that the Reserve Tax undoubted y acted as a catalyst in the polarization of attitudes during the ear y period of industry/government confrontation

Jan 1, 1979

By G. Frithum

In the present paper a new and highly economic route for Fe-separation from HCl leaching processes in hydrometallurgical applications is described. In most ore leaching processes, Fe is involved and needs to be separated; HCl has become an interesting leaching agent, because it can be recycled. Usually a mix of Fe2+ and Fe3+ is obtained which can be hydrolyzed directly (in case only Fe3+) or roasted via pyrohydrolysis (in case of Fe2+) to ferric oxide. Economic oxidation of Fe2+ to Fe3+ is described, and potential technologies for regeneration of HCl with separation of Fe are shown and compared.

Jan 1, 2014

By H. Link

"The extremely low permeability of the water-carrying beds in the nevonian formation of the potash district of Saskatchewan does not permit the injection of cement or chemicals to seal off sufficient water from the shafts to guarantee the safety of the mine. Based on many years of experience with wet shafts in the German and French potash mining industry, Alwinsal Potash of Canada Ltd. decided to have their potash mine shaft near Lanigan, Sask., which was completed in September of 1967, lined by means of an absolutely watertight lining of combined concrete and steel-plate construction.This shaft lining, consisting of two steel shells of welded construction with concrete filled in between, has proved itself before in the German coal mining industry. It guarantees a permanently dry shaft. With this type of lining, time-robbing and very often abortive injections are superfluous and the regular repair and adjusting work as well as the corrosion of conveyances and ropes can be avoided. Above all, however, the danger of a water inrush into the shaft is abolished completely."

Jan 1, 1971

By T. W. Wlodek, Zygmunt Kowalczyk

In the period from 1946 to 1964, the annual output of co al from Polish mines increased from 4 7.3 to 117.35 million tons. In this paper, the methods of bringing about this increase in productivity through the building of some twelve new collieries (producing some 15 million tons annually) and the modernization, reconstruction and extension of some thirty-six older collieries are discussed.

Jan 1, 1967

By N Berkowitz

Slurry pipelining, as now under-stood and practised, can only command marginal interest in Canada, as long-distance railway freight charges in this country are generally lower than slurry pipeline tariffs. Several alternatives to conventional slurry transmission are, however, now emerging, and two such alternatives are briefly discussed with reference to coal pipelining. In one, coal is transported as a suspension in oil; the other contemplates the movement of paste "slugs." Preliminary economic estimates indicate that the resulant process simplification and adoption of common carrier principles could lead to cost reductions that might make Western coal competitive with imported fuel in the power generating stations of eastern Canada. R ECENT appraisals of slurry pipelining techniques, some-what incongruously 'based upon the performance of successful installations (1,2), are making it increasingly apparent that current solids pipelining methods can only command marginal interest as methods of bulk commodity transportation (3). Although some uncertainties remain in matters of detail, it is now generally conceded that long-distance slurry pipelining cannot compete against rationalized railway transportation unless movement of

Jan 1, 1963

By Carl Lausen

Within recent years several mining companies have sent expeditions co the east end of Great Slave lake co determine the mineral possibilities of that area. Little was known of the geography of the region, and even less of the geology; and, not until Blancher's survey was made and the results published, was an accurate map of the lake available. Early explorers followed the Inconnu channel and the north shore of McLeod bay to Port Reliance, and, just prior to Blancher's survey, Hornby showed that the southern passage was feasible. Apparently, but few geologists have ? travelled through the country, for geological information is meager. In 1900, Robert Bell, of the Geological Survey, made a trip to Fort Reliance by way of the north shore of McLeod bay, and he gives a brief description of the geology. The present paper is the result of an expedition into this little-known region by Mr. Geo. M. Douglas and the writer in the summer of 1928. The south shore of Great Slave lake was followed to the east end of Tochatwi bay, and an extensive exploration was made of Kahochella and Pethei peninsulas. The prime object of the expedition was co determine the presence or absence of the copper-bearing Keweenawan basalts.

Jan 1, 1929

By A. del Campo A.

The roast segregation process, which was patented in 1974, makes use of a set of chemical reactions that are different from the traditional sequential oxidation of iron and copper sulfides used by all modem pyrometallurgical processes to treat copper concentrates. It allows metallic copper to be obtained via sublimation of copper chloride at temperatures in the range of 700-800 OC. In addition it avoids melting the concentrate, doesn't require transferring molten materials, doesn't need flux addition and allows nearly all of the sulphur to be removed in one stage as a high-S02 gas stream. Most importantly, it allows a decrease in the use of energy to approximately 6 million BTU/ton of anodes. This represents a saving of approximately 40%, compared to the potential of the most advanced processes presently used. Such a promising process has been waiting for its first industrial application for more than 30 years. This article examines the technical difficulties that have delayed application of the roast segregation process to beneficiate copper concentrates. Special emphasis is made on material handling aspects, discussing the possibility of using a well designed mass flow silo as the main processing vessel to carry out the segregation stage. Cu2007

Jan 1, 2007

By R. A. Crouse

The Tanco pegmatite at Bernie Lake, in the Lac du Bonnet mining district of southeastern Manitoba, is a unique deposit of Li, Rb, Cs and Ta, with substantial reserves of Be and several industrial minerals. This paper summarizes the present state of understanding the regional geology, structural setting, zoning, mineralogy and geochemistry of the pegmatite, and the mining and ore-processing methods used in its exploitation.

Jan 1, 1979

By Andrew J. Freyman, George S. Barry

"Mineral endowment in northern British Columbia and the Yukon Territory was assessed on the basis of geological opinion which was gathered in a quantitative framework of subjective probabilities. The survey area encompassed 364,000 square miles and was divided into 310 cells having dimensions of one degree of longitude by one-half degree of latitude. The response solicited related to tonnage, grade and number of deposits of a particular mineral in each cell. The questionnaire sought an expression of mineral endowment down to mine-able depth as distinct from economic expectations. Details on the questionnaire and responses are presented in a series of contour maps on individual commooities, which illustrate the collective occurrence picture of the respondents. The approach is largely dependent on the cooperation of an adequate number of geologists familiar with the region being examined. This approach to an assessment of the mineral endowment of a region has a wide range of applicability, from the focusing of exploration effort to aiding government and development bodies in the formulation of regional strategies and the planning, for example, of road, rail and power facilities."

Jan 1, 1970

By M. Rylatt, E. Legault-Seguin, C. Mohns

"With energy costs increasing and ore grades diminishing, the role of preconcentration in hard-rock mining operations has gained greater interest. Dense medium separation is a process that can be conducted at particle sizes from 250 to 0.50 mm with high separation efficiency, depending on liberation characteristics of the valuable minerals. Pilot-plant case studies conducted at the SGS Lakefield site are presented, including mineral systems such as spodumene, sulfide-bearing gold ores, and complex sulfide ores. These case studies demonstrate that, for amenable ores, mass rejection of 20–60% is possible while maintaining recoveries of greater than 90%.RÉSUMÉ Au vu de la hausse des coûts liés à l’énergie et du déclin de la teneur des minerais, le rôle de la préconcentration dans les exploitations minières en roche dure présente un intérêt croissant. La séparation (ou concentration) en milieu dense est un processus pouvant être mené sur des calibres de grains de 250 à 0.50 mm avec un rendement élevé de séparation, en fonction des caractéristiques de libération des constituants des minéraux métallifères. Sont présentées dans cet article des études de cas menées dans des usines pilotes du site de Lakefield de SGS, lesquelles incluent des systèmes de minéraux tels que le spodumène, les minerais aurifères sulfurés et les minerais sulfurés complexes. Ces études de cas montrent que pour les minerais présentant les caractéristiques de libération appropriées, il est possible d’atteindre un rejet en masse de 20 à 60 %, tout en maintenant des récupérations supérieures à 90 %.INTRODUCTIONPreconcentration is the process of rejecting gangue minerals while ensuring recovery of valuable minerals prior to more intensive, downstream processing. Preconcentration has been practiced in the industry for many years, and is gaining greater interest as the industry copes with processing lower grade, more difficult ores, which typically require finer grind sizes and incur higher energy costs.The benefits of preconcentration are:• lower mining costs, which allows for nonselective mining;• lower process capital and operating costs (e.g., resulting from reduced grinding, flotation, and fines disposal stages);• increased ore reserves, which provides the potential to treat lower grade ore;• increased mine production without expansion of the existing plant or concentrator;• reduced overall tailings impoundment by converting the reject into a byproduct (e.g., underground backfill or aggregate);• improved efficiency of downstream processes (e.g., silica removal in electric arc furnace feed, removal of softer sliming minerals prior to grinding);• potential application to brownfield operations and greenfield projects; and• a “green” process option, which reduces processing energy consumption;– reduces mill feed;– increases stage metal recovery (higher grade feed);– increases mill metal output per tonne processed;– reduces surface plant, tailings dump, and tailings pond requirements because the plant has a small footprint and can be installed underground; and– can be applied to retreatment of old tailings dumps to recover metal values and reduce environmental impacts (e.g., dissolved metal runoff, acid drainage)."

Jan 1, 2017