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By C. A. Pickles

Microwaves are being applied industrially in a number of fields and possess a number of potential advantages that could be applied in extractive metallurgy. Microwave heating has a number of unique characteristics, which distinguish it from the conventional heating methods. In microwave heating, the absorption of energy occurs at the molecular or atomic level and therefore the heat is generated within the material itself. In conventional heating, the exterior temperature is usually higher than the interior, but with microwave heating, the temperature gradient is inverted and thus the interior temperature can be much higher than that of the surface. The energy densities in microwave systems can be relatively high and this in combination with the low thermal conductivities of oxide ores, can lead to very high internal heating rates. In this research, the application of microwave energy for the reduction of a nickeliferous silicate laterite ore has been investigated. The real and imaginary permittivities are the two fundamental properties which determine the microwave absorption characteristics of a material and these were measured for the ore, both with and without carbon additions using the cavity perturbation technique. The microwave heating and reduction experiments were performed in a 0 to 2 kW CTC microwave system. The effects of power input, processing time, sample mass and charcoal additions on the microwave absorption were investigated. Then reduction experiments were performed and the nickel grade of the magnetic concentrate and the nickel recovery in the concentrate were determined.

Jan 1, 2005

By S. Qian

Galvanic corrosion is a potentially major concern associated with the application of stainless steel reinforcement which is in direct (electrical) contact with carbon steel reinforcement in concrete structures. Judicious use of stainless steel rebar in both new construction and rehabilitation of older structures is a viable, cost-effective option for extending service life and reducing maintenance costs. Questions, however, had arisen about the possibility of increased corrosion due to galvanic effects. This paper investigates the galvanic-coupling behaviours of three different types of stainless steel and carbon steel. Tests were performed both in electrochemical cells and with specimens in concrete inside an environmental chamber. The results show that oxygen reduction on stainless steel is the rate-determining factor for galvanic coupling of these two metals. It is much lower than that of passive carbon steel. As a result, the galvanic coupling of stainless steel with carbon steel will not increase the risk of corrosion of carbon steel reinforcement.

Jan 1, 2005

By J. J. Ferreira, M. L. Thurston, I. L. Chinn, D. M. Rose

"Concerns about using microdiamonds for resource estimation have been raised by workers because multiple diamond populations exist in many parts of the mantle source region, small diamonds in kimberlite could be exposed to proportionately greater levels of resorption and modification, and euhedral microdiamonds could crystallize immediately prior to kimberlite eruption. This paper addresses these concerns; discusses the geology of the mantle, the principal diamond host rocks, and the impact of mantle processes; compares micro- and macrodiamond properties and features; and outlines steps to identify and mitigate the risk of diamond resorption and its impact on the diamond grade-size relationship.RÉSUMÉ Des travailleurs se sont interrogés sur l’utilisation de microdiamants pour estimer la ressource; en effet, de multiples populations de diamants existent dans plusieurs secteurs de la région source dans le manteau. Des petits diamants dans la kimberlite pourraient être exposés à des niveaux proportionnellement supérieurs de résorption et de modification; de plus, des diamants idiomorphes pourraient cristalliser immédiatement avant l’éruption de la kimberlite. Le présent article traite de ces questions, discute de la géologie du manteau, des principales roches-mères des diamants et de l’impact des processus dans le manteau, compare les propriétés et les caractéristiques des micro- et des macrodiamants et définit les étapes pour identifier et mitiger le risque de résorption des diamants et son impact sur la relation entre la taille et la qualité des diamants."

Jan 1, 2016

By A. Bois-Brochu, G. Morin, G. Marin, M. C. Parr, J. Carignan

The presence of an alpha case on titanium parts produced by investment casting is problematic and has to be eliminated. The traditional techniques for the evaluation of its thickness are metallographic measurements and micro-hardness profiles. To obtain a better understanding of how the alpha case is formed with the underlying objective of limiting its depth, the present study proposes to characterize the microstructure and the chemical composition of the alpha case. Electron microprobe analyzer (EMPA) linescans were used to quantify the oxygen and substitutional elements that come from the mould and promote the alpha case formation. The chemical profiles were correlated with metallographic and microhardness measurements. For microstructure, optical microscopy (etched and polarized light analysis) was used. For phase analysis, samples were mechanically polished step by step and analysed using X-ray diffraction and optical microscopy. Furthermore, surface analysis techniques such as XPS and Auger Microscopy were evaluated but results were found to be inconclusive because the formation of the oxide layer was faster than its ablation and the matrix could thus not be analysed. The alpha case was observed on a Ti-6Al-4V step block casting.

Jan 1, 2014

By Roger Davieds

FACT: a company?s profitability (or loss) is directly related to the efficiency and effectiveness of its maintenance operation. Fact: in order to contribute in a positive manner, maintenance must understand what its true purpose is in the organization. It is easy to say our main purpose is to increase: ?equipment uptime ?OEE ?asset life cycle We all understand this; so does management.

May 1, 2010

By H. Y. Sun, Q. Y. Tan, X. P. Niu, L. Li, Y. Jia, R. M. Ruan

During bioleaching processes of sulfide minerals, the sulfide minerals act as the natural habitats for acidophiles, of which, most are autotrophic iron and sulfur oxidizing microbes. These microbes acquire energy by oxidation of sulfide minerals, and play crucial role in bioleaching processes. In the industrial bioleaching heaps, microbial community and their activity are highly related to engineering configurations, while the optimized industrial operation can help to fast dissolution of aim minerals and acid/iron balance under optimized microbial condition. Microbial community succession and activity formation, the function of microbes to mineral dissolution, the mechanisms to promotion and inhibition of sulfide minerals oxidation, and the industrial instances for microbial community regulation were reviewed. For these instances, promoted microbial activity helped to fast pyrite oxidation for sulfuric acid generation, which realized zero sulfur acid addition to the irrigation solution in the initiation of a bioleaching heaps. High microbial activity by optimized operation parameters improved Cu leaching efficiency during the heap bioleaching process. And also by inhibition of microbial activity, especially the iron oxidizing microbes, the excessive pyrite oxidation can be inhibited, which helped to the acid/iron balance during heap bioleaching. INTRODUCTION Around the world, high grade copper ore are exploited, while barely new high-grade deposits are succeeded, the copper grade of ore deposit is constantly decreasing. The increasing copper demands worldwide requests to process these low-grade ore deposits. Processing of low-grade ores are not economical by usual extraction processes. Heap leaching is a cheaper process for recovery of low-grade ores, and has been applied to extract valuable metals from sulfide minerals worldwide, such as copper, gold, uranium and nickel (Gericke et al., 2009). Heap leaching process has greatly decreased the economic grade and expanded the recoverable ore reserve worldwide (Brierley, 2008). It is usually carried out in the open environments, and could process huge amount of ore (usually in millions of tonnes in one reactor) in the heap reactor (Gericke et al., 2009). For copper sulfide, especially the secondary copper sulfides, heap (dump) bioleaching is successfully applied. Heap bioleaching process is cost saving, and sometimes can be achieved without adding chemical into heaps, by microbial fixing of the atmospheric N2 and CO2, and generating oxidant Fe3+ and sulfuric acid in heaps from oxidation of sulfide minerals. Also heap bioleaching is environment friendly by cycling use of the leaching solution, and without exhaust emission.

Jan 1, 2019

By Y. Masuda, Y. Nakamura, K. Haraguchi, A. Taniguchi, K. Arita

Availability of the elements originating from steelmaking slag for various marine phytoplankters including purely cultured strains and natural populations was tested in land and shipboard laboratories. The results obtained demonstrate that, although their solubility was not uniform among different slags, dissolved iron, silicate and phosphate from the slag stimulate phytoplankton growth. No negative effect of the slag addition on their growth was observed at lower dose, e.g. less than 200 mg/l. Since most coastal waters are the hypernitrogenous environment due to anthropogenic load of ammonium, the slag can be an ideal source of silicate and phosphate, which restore the hyper-nitrogenous condition into truly eutrophic condition with balanced Redfield ratio. In so-called HNLC (high-nitrate low-chlorophyll) oceanic areas such as the Southern Ocean and the subarctic North Pacific, where iron is almost only limiting factor of the phytoplankton growth, the slag could also be a source of iron and enhance CO2 fixation by phytoplankton photosynthesis. (Key words: carbon deposition in deep-sea, marine environmental remediation, phytoplankton, slag as a source of iron, phosphate and silicate.)

Jan 1, 2004

By G. Guzman

In the framework of the optimization of Teniente Converter operation the new system of automatic flux feeding through gar-gun was implemented in the Potrerillos Smelter, Codelco Chile, Salvador Division. The control algoritm based on simple iron and silica balance adjusted by empirical coefficients was incorporated in the logical programmer. The programmer works in real time gathering information from the plant instrumentation events and introduced chemical assays of concentrate, slag and flux. Through the auto-tuning of the automatic operation the criterions of optimal flux dosage were determined. Four month of operation of the automatic flux feeding system demonstrated the stabilization of magnetite content in the slag in the narrow range from 18 to 20% and the decrease of flux consumption, corresponding to annual savings US$ 340,000. Additionally, the automatic system helps operators in the control room in fast determination of optimal fluxing and avoid the errors in flux dosage affecting the slag quality and its impact on refractory wear.

Jan 1, 2007

By Paul-Henri Girard

La Mine Agnico-Eagle division Laronde situé à Cadillac, est un producteur d?or, d?argent, de cuivre et de zinc. Cette propriété est situé dans les cantons Bousquet-Cadillac le long d?une des ceintures géologiques les plus productives au monde. La mine Laronde a débuté la production en octobre 1988 à un rythme de 1360 tonnes par jour. Ensuite, elle a augmenté son rythme de production successivement à 1800 TPJ en 1990, 3300 TPJ en janvier 2000 et 4500 TPJ en octobre 2000. Agnico-Eagle, fondé par feu Paul Penna, a toujours eu comme politique la participation des employés aux décisions de la compagnie pour le déveleppement de celle-ci. Cet écrit va permettre de mieux comprendre la façon dont la division fût développé.

May 1, 2001

Arguably the SMC Test® has become the most popular laboratory hardness test in the world with over 17,000 tests having been completed to date, covering over 650 different ore bodies. It is now routinely used in design, optimisation and orebody profiling projects. The test is unique in that from relatively small amounts of drill core it simultaneously provides parameters that are used in simulation modelling of AG/SAG and crushing circuits as well as work indices that are used in power-based equations for predicting the specific energies of AG/SAG/Crushing and HPGR circuits. The very large data base that has been accumulated has provided the opportunity to study the differences in variability from deposit to deposit. This paper describes and discusses the trends that have become apparent from the study of this data base. Recommendations for appropriate selection of sample numbers are also made which are based on these trends.

Jan 1, 2012

This paper outlines the position and capabilities of Western Canada's bituminous coal industry, and indicates the increasing importance of Japan as an export market. The use of coal in Japan is reviewed, especially as regards future trends, and an appraisal is made of Canadian coal in comparison with domestic Japanese coal and imports from other countries. The importance of maintaining a solid nucleous within the Canadian bituminous coal industry is emphasized. I N RECENT years, Japan has emerged as a valuable market for Canadian exports. The first major product exported in volume to Japan was wheat, which has become very successfully established in Japanese markets. Following this, iron ore gradually found a market in Japan, with exports usually based on long-term contracts. This iron ore was produced entirely in British Columbia In 1958, the Western Canadian bituminous coal industry -jointly with the Dominion Coal Board -sent an official mission to Japan to investigate the

Jan 1, 1964

By S-E. Vandat

The goal of this work was to select an appropriate electrode for dummy load of diesel engine in fully salt-water in the DESA factory. The electrochemical corrosion rate of general structural steel, commercial pure aluminum and cathode copper calculated as weighting, volumetric and commercial in fully salt-water by city power. After several tests and then applying the fuzzy logic method, it was determined that general structural steel is the best selection for this purpose.

Jan 1, 2005

Presentation Overview Corporate Overview Kutcho Project History Exploration Development Permitting Capstone -Pursuit of Value Building a mid-tier copper producer focused in the Americas Two operating copper mines; Cozamin& Mintomines High grade and low cost 2010 forecast: 80-85 million pounds of copper in concentrates Total Cash Costs* of ~US$1.10/lb to US$1.20/lb of payable copper produced Significant by-products of gold, silver, lead & zinc Growth potential Further expansions at existing Cozamin& Mintomines High grade copper development: Kutcho project, BC Investments in Nevada Copper & Silver Wheaton 100% North American assets Low risk ?Canada & Mexico ?Conventional operations

Oct 1, 2010

This paper focuses on the dissolution of various Manganese based compact additions into liquid Magnesium. The experimental procedure employed cylindrical compacts with various Manganese compositions. The various temperatures of the additions and the Magnesium bath were measured simultaneously during the immersion of the additions into Magnesium bath. The exothermicity level of these additions during their dissolution into liquid Magnesium was determined. The relation of the exothermicity level with the dissolution kinetics was also examined. In addition, SEM and EDX work was conducted for additions, which were withdrawn from the Magnesium bath. Finally, the recovery of these additions was estimated by taking samples from the Magnesium bath and conducting ICP analyses.

Jan 1, 2006

By G. M. Ritcey, B. H. Lucas

In the conventional alkaline leaching of concentrate containing nickel, copper and cobalt, copper is usually removed from the system, prior to nickel reduction, by sulphide precipitation. A new process is described for the selective extraction of copper and separation from cobalt and nickel, using liquid-liquid extraction. General Mills LIX-63 dissolved in a kerosene diluent is the extractant. Trace amounts of co-extracted cobalt and nickel are easily removed by a scrub treatment, and copper is recovered from the extract by sulphuric acid stripping, thus providing a solution amenable to the oroduction of electrolytic copper. Estimated processing costs are included together with a proposed flowsheet.

Jan 1, 1972

By C. P. Verschuren, P. W. Kingston, W. F. Caley

"In recent years, there has been rapid growth in the use of natural stone building and construct ion products. The largest growing markets are for pre-fabricated natural stone panels for interior and exterior wall facing and flooring. This increased demand is attributed to advanced quarrying and processing technologies, renewed appreciation for the aesthetic appeal of natural stone, and to the superior durability of natural stone when compared to glass, steel, and concrete. Geologically, plutonic rocks, and to a lesser extent marble and limestone/dolostone, are used extensively for these applications. This paper details the economic structure of the dimension stone industry, describes the necessary characteristics of a stone quarry, and outlines the geological criteria which favour an economic quarry.INTRODUCTIONThe world building stone industry has remained relatively stable over the last 5 to 6 years. In contrast, the North American stone industry has experienced substantial growth during that period. The increased use of commercial granite is primarily responsible for this growth, where use as exterior wall veneer for commercial, industrial, and institutional buildings represents the largest and fastest growing market.This increased usage in the construction industry has been sparked by the application of new technologies in quarrying, processing and installation , ma king natural stone more competitive with man-made materials which are energy intensive to produce, and have risen dramatically in price. The development of safer, time-saving stone installation techniques has also appealed to the liability-conscience construction industry. Finally, there is a trend by designers and architects toward utilizing long-la sting weather-resistant building materials, and a renewed appreciation of the aesthetic appeal of natural stone. The other large user of granite is the monument industry of North America which, although it has decreased slightly in recent years, still consumes approximately 40% of all commercial granite produced. The local use of commercial marble has remained relatively stable, and North America still relies heavily on European sources and suppliers. There has been some concern over the use of marble for exterior applications in areas subject to acid rain, and in colder climates where the marble ma y be vulnerable to freeze thaw cycles. Despite these concerns, the greatest problem is not with the structural breakdown of marble but the inability of some marbles to retain their polished finishes in the se environments. As a result, there has been an increase in the use of granite at the expense of marble for exterior applications. Finally, commercial marble is used extensively for interior flooring, wall s, counter tops, furniture, sculptures, and stairway components"

Jan 1, 1989

By Sean McClenaghan

Significance Setting Size Production Value History of Discovery Zn and Pb at Austin Brook Brunswick Belt Exploration Discovery Hole Geology Structure Metal Zonation Directed Research Incremental Ores Precious metals Closure and Beyond Mining Remnants Tailings

May 1, 2013

By V. P. Mehrotra, D. W. Fuerstenau, A. -Z. M. Abouzeid

The use of pulverized coal for electric power generation results in the production of vast amounts of fly ash. One potential use for waste fly ash is the production of pellets for lightweight aggregates. This paper is concerned with the role of the physical and chemical characteristics of two different fly ashes in governing their agglomeration or pelletization behavior and their strength characteristics. In batch balling experiments, fly ash pellet growth was found to be extremely sensitive to the amount of moisture added. One ash (Mohave) exhibits marked pozzolanic activity whereas the other (Jim Bridger) does not. The pozzolanic activity has a very pronounced effect on pellet growth kinetics, moisture requirements, and the effect of various additives on growth kinetics. Slow drying under ambient conditions produces strong pellets from Mohave ash whereas Jim Bridger ash pellets lacking in pozzolanic activity are weak. Rapid drying at high temperatures results in weak pellets because water necessary for hardening is driven out of the pellet. Steam curing enhances pellet strength. Locked-cycle pelletizing experiments exhibit expected oscillation in pellet production rates and attendant fluctuations in pellet green strength.

Jan 1, 2004

By F. Habashi

Magnesium is the eighth most abundant element in the earth's crust, It occurs in nature in sea water, brines, and a number of minerals, Metallic magnesium was first isolated by Humphry Davy (1778-1829) in England in 1808 via electrolysis of anhydrous magnesium chloride with a mercury cathode, Antoine Bussy (1794-1882) in France extracted the metal in 1828 by reducing fused magnesium chloride with metallic po¬tassium vapour, The first industrial production of magnesium by electrolysis of molten carnallite began in 1886 in Hemelingen in Germany, In 1940 Lloyd M, Pidgeon (1903¬1999) in Canada pioneered the first industrial metallothermic magnesium extraction plant based on the reduction of dolomite with ferrosilicon under vacuum, Since then the magnesium industry developed further and a variety of processes are presently used.

Jan 1, 2006

By Alvis L. Lisenbee, Colin J. Paterson, Mustafa M. Hariri

"Abstract-The schist-, sediment-, and intrusion-hosted Tertiary Au-Ag hydrothermal deposits of the northern Black Hills, South Dakota are localized and controlled by various types of fractures. This study is an attempt to distinguish between and discuss the possible causes of these fractures in three mines: Richmond Hill, Annie Creek - Foley Ridge (ACFR), and Gilt Edge.Five models based on the structural and tectonic settings of the northern Black Hills are proposed for the fracture origin. In Richmond Hill mine, mineralized fractures within the schist-hosted deposits are in the form of veinlets and stockworks. Larger veins filling open spaces along schistosity planes are also present. Fractures in Richmond Hill mine are related to breccia pipe emplacement and influenced by the Precambrian foliation.Fractures in sediment-hosted (ACFR) and intrusion-hosted (Gilt Edge) deposits are mode I systematic joints. These fractures, and similar ones examined in seven locations outside the mines, are related mostly to the formation of the Lead-Deadwood dome. Fracture trends vary from one area to another depending on their location with respect to the dome. Other factors, such as the Black Hills uplift, pluton emplacement, and Precambrian foliation, may also affect the fracture trends. The proximity of the mines to domes formed by multiple intrusions, the associated fracture patterns and density, and existence of breccias, may be used in exploration for similar deposits in the northern Black Hills or other areas of similar geologic settings."

Jan 1, 1995