Search Documents

By G. A. Highcock

"Operations started at BCL in December 1973J and the smelter is currently in the seventh year of its fifth campaign. The next major shutdown is scheduled for 1995. During the current campaign, a number of major on-line refurbishments have been carried out without any significant disruption to production. These include the complete rebuild of both drying plant electrostatic precipitators, the installation of a new electrostatic precipitator at the flash furnace, the conversion to a distributed control system throughout the smelter, and the installation of a converter air blowing control system.IntroductionBCL Limited operates a nickel-copper mine in northeastern Botswana approximately 100 km southwest of Francistown. Surface operations for the production of high-grade nickel-copper matte at a design capacity of 42 000 metric tonnes per annum, were commissioned in December 1973. Detailed descriptions of the mine and surface facilities have been presented previously(1-3).Over the years, a number of major engineering modifications and metallurgical projects have been carried out to overcome operating difficulties. improve metal recoveries, increase production rates and provide a better working environment.One of the major results of these projects was an increase in the 19805 in flash furnace feed capacity from 70 t/h to 120 t/h of new concentrate with a nominal feed rate of 105 t/h being achieved.(4)Because of the ore characteristics, i.e. a high mass fraction of ore reporting to concentrate, BCL operates one of the highest capacity spray drying plants and flash smelting furnaces in the world(5).A schematic of the BCL smelter is shown in Figure 1. The smelter is now in the seventh year of its fifth campaign, with the next shutdown scheduled for mid-l99S. In this campaign, the following major projects were completed:"

Jan 1, 1995

By H. A. Kramer

The Flin Flon mine is at present hoisting 5,000 tons of ore daily. In 1943, a peak production of 6,188 tons daily was maintained. Before discussing secondary blasting, it is felt that a short review of stoping procedure will be of value. A list of papers dealing with various phases of the mining operation is appended. Stoping Practice Stopes vary in width from 30 to 150 feet, in length from 200 to 450 feet, and in height from 200 to 500 feet. A typical stope would be 300 feet long, 300 feet high, and 90 feet wide. The dip of the orebodies varies from 60° to vertical, with an average of 82°. The ore is heavy, having a specific gravity of 4. Both sub-level benching and radial drilling are practised. Blast-hole diamond drills are responsible for 85 per cent of the total production. Two sizes of hole are drilled at present, 11 7 6 -inch and 1%-inch. For bench drilling, the burden on the 1 7/16-inch hole is six feet, with holes on 8-foot staggered centres; in radial drilling, the burden is six feet, with nine feet between the toes. The burden on the l 5/8-inch hole is eight feet with holes on 11-foot centres, or 13 feet on the toe of fanned holes. Holes are blasted with two No. 8 instantaneous electric caps per hole, using 403 Polar Forcite. A powder charge of 0.15 pounds per ton is used, with a tonnage factor of 5 and 6.4 per foot drilled for the two sizes. Two rows of holes are blasted together. Fragmentation is satisfactory with the above drilling pattern and powder charge. However, some overbreak and fall-off locally results in oversize material. It is estimated that, after primary breaking, 75 per cent of the ore will pass through the grizzly openings and 15 per cent will pass the draw points, leaving 10 per cent that must be broken further to pass the draw points.

Jan 1, 1946

By H. Tetu, F. Pells

"The copper-molybdenum property of Brenda Mines Limited is located in the Okanagan district of British Columbia, approximately 25 miles west of Kelowna. The Okanagan Valley is a resort and fruit-growing area, and therefore pollution control measures are more stringent than in some remote areas.The Brenda plant began production in April 1970 and is operated at a rate of 24,000 tons per day. The plant site is located at an elevation of 4,800 feet, which is approximately 3,600 feet above the level of Okanagan Lake. The site is in the Okanagan drainage basin.The major consideration in the design of the system was the prohibition of any downstream discharge. It was therefore necessary to redaim as much water as possible and to minimize the addition of fresh water to the system. The maintenance of a water balance is of critical importance.This paper will outline the major design criteria for the systems and the site investigations which were carried out. The design and construction of the facilities will be de-scribed and current operating experience will be outlined."

Jan 1, 1971

By Wang Wenqian, George W. Poling

"Devices and flowsheets for recovering fine placer gold are reviewed. Inefficiencies of gravity processing techniques are documented and discussed. Prospects of combining gravity and froth flotation techniques are presented. Possibilities of using other separation techniques, such as magnetic and electrostatic devices are also discussed.IntroductionSeveral new methods for beneficiating different types of placer ores have been developed in the last two decades. Improved efficiencies in the recovery of fine particles have been achieved by improving gravity flowsheets and machines as well as by developing multiple treatment techniques involving flotation, magnetic and electrostatic separations. Placer gold processing, however, has been an exception to some extent. Gravity concentration using riffled sluices accompanied by mercury amalgamation is still the main method in use today. Because of this, the recoveries of fine gold and the other associated values are often similar to those achieved several decades ago. For example, very few sluice systems recover significant placer gold finer than 100µm in size.Only a few proposals for using alternatives to simple gravity methods for recovering fine placer gold can be found in the published literature. The fixed, low gold price discouraged research in this field for many years. Development of more efficient processes has not kept pace with the recent rapid escalation in the price of gold. Froth flotation for saving fine placer gold might now prove economic, for example. This paper reviews literature published on the recovery of fine placer gold over the period 1907 to 1980. Suggestions for improving the performance in this field, based on the authors' current testwork, are also presented."

Jan 1, 1983

By N. Musee, N. Kornelius

This study presents a neural network approach to modelling the liberation of gold bearing ores. A complete mineralogical analysis of unmilled and milled ores, including gold deportment and gangue content are used as inputs to a self-organising neural net which generates order preserving topological maps. The arrangement and shapes of these clusters are coupled to unmilled free gold data to predict gold liberation in milled ores (absolute error: 4.2%). Moreover, the self-organising maps were diagnostic of the quality of data used, indicating that the relationship between particle size and gangue material content requires further investigation.

Jan 1, 2005

By Bruno Bussière

Acid Mine Drainage (AMD) from mine wastes is one of the most environmental challenge currently facing the mining industry. AMD is the result of the natural oxidation of sulphides exposed to air and water. When mining wastes have the potential to produce AMD, these reactive wastes have to be managed to meet existing environmental regulations. The LTA site (property of Barrick Gold Corp.) contains sulphide tailings that have the potential to generate AMD. The closure option Barrick selected was to construct a multilayered cover with capillary barrier effects (CCBE). The main objective of this CCBE is to prevent the production of Acid Mine Drainage (AMD) from the tailings stack covering an area of approximately 60 ha. Since its construction in 1996, the cover has been monitored to evaluate its performance. Two of the measured parameters are volumetric water content and matrix suction. This paper presents some of the main results from the monitoring program that started seven years ago. The results show that the cover is largely able to maintain a high degree of saturation (greater than 85%) in the moisture-retaining layer. The actual performance of the CCBE on the flat surface of the 60 ha site is even better than expected at the design stage. The area that requires more specific attention with the LTA cover is the influence of slopes that can reduce the performance of the CCBE during dry periods. However, these effects seems to be local and do not significantly affect the overall performance of the CCBE to mitigate the production of AMD at the LTA site.

May 1, 2003

By C. Edwards

ABSTRACT: Milling operations in northern Saskatchewan’s Athabasca Basin have produced uranium continuously since 1975. During that period, the Athabasca Basin has been one of the world’s premier uranium camps, yielding more than 660 million lb (299,370,964 kg) of U3O8. In this paper, the author describes former and current milling operations and discusses why and how the milling process has changed and developed over the past 35 years. The author’s considerations for the future of uranium extraction in the Athabasca Basin conclude the paper.

Jan 1, 2012

By N. Tounsi

The use of analytical modeling of continuous chip formation in conjunction with orthogonal cutting experiments was presented in the open literature to identify the coefficients of material constitutive equation within the practical range of stress, strain, strain rate, and temperature encountered in metal cutting. Identification of reliable constitutive data was hampered by a lack of a reliable model for the prediction of the primary shear zone thickness that affects directly the effective strain rate field. An original analytical model to determine the primary shear zone thickness is proposed in this paper. It is based on the mechanics governing the material flow in the primary shear zone. Based on the distribution of the hydrostatic pressure and the forces measured from orthogonal cutting tests, the model that describes the thickness of the primary shear zone is derived. To validate the model, FE simulations of chip formation using DEFORM3D were carried out for different materials and cutting conditions. The results of the analytical model are in reasonable agreement with FEM results.

Jan 1, 2006

By Pan Zhao, Yan-Nan Wang, Fei-Long Liao, Can Cai, Kai-Song Wu

"What are the basic physical parameters and main geometric parameters that are capable of representing the microscopic characteristics of rock? How can these parameters be used to accurately describe the macroscopic mechanical behavior of rock? With such questions in view, and based on the microcosmic structure analysis of rock slices, this paper presents a rock skeleton-pore structure model, holding that rock's mechanical behavior depends on the properties of rock skeleton materials and the form, size and distribution pattern of pores. According to rock stress and deformation behaviors, and in line with the skeleton-pore structure model, an essential mechanics theory for rock is advanced. The assumption that the skeleton materials are incompressible in volume and an introduction of logarithmic strain, generate the relation between porosity and apparent strain. Then, the notion that positive damage and negative damage are represented in terms of porosity is put forward; threshold value of porosity is derived by the damage threshold value of apparent volume strain; a general damage variable of rock is obtained; eventually, with the skeleton-pore model as the groundwork, a global damage constitutive equation is developed, which, with definite physical significance and material parameters to be easily determined, is convenient to apply. It has been proved that the results calculated with this new equation are well in agreement with experimental results.INTRODUCTIONRock is a form of material that contains pores, cracks and skeletons. Skeletons are composed of particles and cements. Pores or cracks within rock actually undermine the assumption of material continuum in solid mechanics. Hence, grave errors — or even false results — are inevitable if some solid mechanics theory is quoted in the discussion of rock mechanics. Many researchers in the field of rock mechanics have attempted various remedies, but the outcome is far from satisfactory — a mechanics theory for rock, in its true sense, has not been established."

Jan 1, 2015

By T. Johnson, K. Lambrych, D. Kelley

Materials for construction of equipment used in hydrometallurgical plants are selected based on a combination of their ability to perform as required in aggressive process environments as well as their cost. As a material of construction, fiber reinforced plastic (FRP) has been shown to provide equal if not improved durability relative to alternative materials such as corrosion resistant alloys at a considerably lower cost. This is particularly true in the case of equipment used in acid leaching processes for copper, cobalt, nickel and rare earth elements. The selection and extensive use of FRP over alloys in new hydromet plant construction in North and South America illustrates this advantage of FRP effectively. This paper will compare corrosion performance and cost of plant equipment fabricated with stainless steel alloys and FRP made with Epoxy Vinyl Ester thermoset resins. Real world case histories for FRP piping, storage tanks, extraction vessels, and electrowinning cells combined with laboratory based corrosion studies will be reviewed to demonstrate how FRP materials are selected for hydrometallurgical equipment.

Jan 1, 2015

By J. M. Cummings

The importance of controlled sand properties to the production of quality castings has been recognized by foundry men for many years, but the maintenance of requisite standards results in a relatively high sand consumption, which in steel foundries, for instance, may range from half a ton to over one ton of sand per ton of finished casting. During the war, obtaining and maintaining adequate sand supplies became a serious problem in many foundries, owing to increased wartime production and serious 'bottlenecks' in transportation. As a result, considerable interest was aroused in the possibilities of various sand reclamation systems by which up to 85 or 90 percent of discarded sand may be returned to a usable condition. During the past five years or so, a number of sand recovery installations have been made by both ferrous and non-ferrous foundries in Canada and the United States, and have resulted in substantial reductions in sand costs in every case. The possible benefits of sand reclamation are particularly apparent in British Columbia where no suitable sands for steel and heavy iron foundries occur naturally, and where freight costs on imported sands are considerably higher than initial selling prices. This is well illustrated by the fact that silica sand, which sells for about $2.00 per ton at pits in Illinois, is laid clown in British Columbia for around $11.00 or $12.00 per ton. The operating costs quoted for certain of the reclamation schemes, i.e. $0.25 to $1.50 per ton, may actually be no higher than the cost of waste sand disposal in city-located foundries. In view of the foregoing considerations, the British Columbia Research Council has undertaken a study of the possibilities for sand reclamation, with particular attention directed to its application in local steel foundries. No commercial occurrences of silica sand are known in the Province, and, with this in view, the Council previously investigated the possibility of recovering silica sand from local impure sands. Results were definitely encouraging, but it was felt that the present market is too small to permit economical production by the method developed.

Jan 1, 1947

By Anton Sizo, Alexey Klyashtorin

The Gunnar uranium mine operated from 1953 to 1961 on the shore of Lake Athabasca, in 1964 the site was abandoned, and the mine pit flooded. In 1981, the pit was found to be stratified with a chemocline at ~70 m by a sharp change in conductivity and TDS. The uranium concentration was ~700 μg/l on the surface, 320 μg/l at 50 m, and 2,900 μg/l at 110 m. The Ra-226 concentrations were 0.1, 0.06, 0.12, and 0.4 Bq/l. By 2017, the chemocline was ~60 m deep. The highest uranium concentration was 1150 μg/l and the lowest concentration (220 μg/l) was attributed to the chemocline. In the deeper column, the uranium content varied around 750 μg/l. The uranium distribution down the pit profile was aligned with DO, ORP, and TDS. Ra-226 averaged to ~0.4 Bq/l, Ra-226 and uranium profiles were inversely related with the respective maximum and minimum attributed to the chemocline. The uranium and radium amount accumulated in the pit by 2017 was 3,420 kg and 2,163 GBq, respectively. The uranium and radium apparent accumulation trend estimates to 64 kg/y and 41 MBq/y, respectively. A stable chemocline and no concentration gradients in the other parts of the pit suggest that the contaminants are unlikely to inflow from the bottom opening or outside the pit, but rather are mobilized from the pit walls. The contaminants are not in a steady state, and concentrations of both uranium and radium are likely to increase slowly in the future if no remediation occurs.

Jan 1, 2020

By G. J. McTeer, D. L. Verhelst, D. J. Rioux

Teck Metals Ltd. operates an integrated zinc-lead complex at Trail, British Columbia, Canada. Since 1997, KIVCETTM flash smelting technology has been utilized for the treatment of zinc plant residues and lead concentrates. Trail Operations’ furnace uses four water-cooled jackets for bullion tapping. This paper provides an overview of KIVCET bullion tapping for the past 16 years, and discusses successes and challenges encountered with respect to operations, training and monitoring.

Jan 1, 2015

By X. Cao, J. J. Jonas, Wanjara. P., J. Gholipour, E. Dalgaard

The linear friction welding (LFW) behaviour of near-ß titanium alloy Ti-5Al-5V-5Mo-3Cr (Ti- 5553) was investigated. Microhardness measurements were performed in order to evaluate the mechanical properties of the welded material. The linear friction welded (LFWed) Ti-5553 was examined with optical microscopy and scanning electron microscopy (SEM) to evaluate the microstructure’s response to the thermomechanical conditions. Characterization of the welds included analysis of the microstructural features of the weld region and thermomechanically affected zone (TMAZ) in relation to the parent material.

Jan 1, 2010

By X. Z. Yuan

Contamination introduced by the impurities from the feed stream can impact the PEM fuel cell performance dramatically. The presence of these unwanted trace species such as CO, H2S, NH3, can adversely affect the fuel cell functioning. It has been reported that the major impact of CO and H2S contamination on the fuel cell performance is kinetic while the effect of NH3 contamination is speculated as membrane conductivity reduction only. In this paper, a model regarding the NH3 contamination is described and the mechanism of the NH3 contamination is illuminated by the model calculations.

Jan 1, 2005

By S. Nafisi

Permanent mould casting may be regarded as a near net shape manufacturing process where simple to very complex shaped engineering components are fabricated with high degree of precision in a metallic mould, In this group, High Pressure Die Casting (HPDC), have attracted more attention because of its production rate, where both liquid and semisolid metals (SSM) can be cast with high degree of precision and versatility. The SEED process, Swirled Enthalpy Equilibration Device, the new process for semi solid metals slurry production route, consists of two steps: The initial step involves extracting specified amount of heat from the molten metal to generate liquid-solid slurry, i.e, mushy structure, followed by drainage of remaining liquid to produce a compact free standing feedstock for rheocasting operation. In this paper, microstructural evolution during the process and some initial casting results of automotive components an also reported.

Jan 1, 2005

By Long Han, Beijing General Research Institute of Mining and Metallurgy, Yu Xie, Yunhai Zhang, Yangge Zhu, University of Science and Technology Beijing, Yanbo Shang, Xingrong Zhang

"The first-principles method was employed to study the adsorption of hydroxyl calcium (CaOH+) and hydroxyl (OH-) on hematite and quartz surfaces. The calculation results suggested that OH- preferred to interact with the active Fe sites on the hematite surface, whereas OH- adsorbed on the quartz surface by weak hydrogen bond. Though CaOH+ could easily adsorb on the hematite and quartz surfaces by the formation of Ca-O bond, the covalence formed on the quartz surface was apparently stronger than that on the hematite surface, meaning a stronger and more stable adsorption. CaOH+ adsorbed on quartz surface was mainly through the interaction of O-2p and Ca-3d states, and this interaction on hematite surface was weaker.INTRODUCTIONIron Increase and Silicon Reduction Technology (Yu & Duan, 2002) of hematite is mainly through the reverse flotation (silica is floated away from the iron concentrate). There are two ways to achieve this (Houot, 1983). One is to collect quartz by cationic collector directly; the other is to activate quartz by lime and then collect it by anionic collector. There are two main different views with respect to the mechanism of quartz activation: mono-hydroxyl compound theory (Fuerstenau, Rice & Somasundaran, 1965; Fuerstenau & Palmer, 1976) and surface hydroxyl precipitation theory (Hu & Wang, 1988; Wang & Hu, 1990). The former indicated the formation of the mono-hydroxyl complex is one of the two criteria of quartz flotation. The later theory, on the other hand, suggested that surface precipitation is the adsorption of active species of metallic ion on quartz surface. However, most of those researches are based on the solution chemistry of flotation and little is done at the microscopic level.In this paper, by the help of first-principles calculations, the adsorption models, bonding conditions, Mulliken charge populations and adsorption energies of hydroxyl and calcium hydroxyl ions (OH- and CaOH+) on hematite (001) and quartz (100) surfaces were investigated to find out the lime activation of quartz at atomic level, which is significant for the researches of quartz activation theoretically and practically."

Jan 1, 2016

By P. Hickey, G. Hubert, P. Healy

"J. S. Redpath Limited, an underground contractor with a worldwide presence, has implemented innovative techniques in various projects in Canada to shorten the development cycle. Conventional methods currently used for installing primary ground support are compared with the Australian technique of bolting and meshing with jumbos equipped with twin telescopic booms, in-cycle shotcreting, and the use of two jumbos and two scissor bolters set up side by side in wide headings. Recommendations and lessons learned are presented with the aim of providing realistic expectations with regard to development advance rates in a mining environment.RÉSUMÉ J. S. Redpath Limitée, un entrepreneur minier souterrain d’envergure mondiale, a complété plusieurs projets au Canada où des techniques novatrices ont été mises en oeuvre pour raccourcir le cycle de développement. Cet article présente une comparaison entre les méthodes conventionnelles fréquemment utilisées pour le support de terrain, la technique australienne de boulonnage et d’installation de grillage au moyen de jumbos équipés de flèches télescopiques doubles, du béton projeté appliqué durant le cycle de développement et de l’utilisation de deux jumbos et deux boulonneuses côtes-à-côtes dans des galeries de grandes dimensions. Les recommandations et les leçons apprises sont présentées dans le but de fournir au lecteur des attentes réalistes quant aux taux d’avancement du développement dans un environnement minier."

Jan 1, 2016

By Yann Sivry, S. Subramanian, Divyasree C. Prabhakaran, Jean Riotte

The potential of a bacterial strain isolated from water samples collected from a chromite mine in Odisha, India has been assessed for the bioremediation of hexavalent chromium, a toxic environmental pollutant. The isolate was identified as Sphingopyxis sp., a Gram negative bacterium, adopting molecular biological protocols and biochemical characterization techniques. Detailed investigations on the bioremoval of Cr(VI) were carried out using Sphingopyxis sp. cells and the various parameters affecting the biosorption process were evaluated. About 55 % biosorption of Cr(VI) was obtained using Sphingopyxis sp. bacterial cells and the residual chromium in solution was found to be bio-reduced to the trivalent form, namely Cr(III). Thus, complete bioremediation of Cr(VI) could be achieved using the mine isolate, with contributions from both biosorption and bioreduction mechanisms. The Cr(VI) biosorption isotherm obtained for the isolate was found to follow a typical Langmuirian behavior and the free energy value of biosorption was determined to be ~-25 kJ/mol, indicative of involvement of chemical binding forces in the bioremediation process. The chromium biosorption kinetics by the isolate followed a pseudo second order reaction. The FTIR spectral studies revealed that carboxyl, hydroxyl, amino and phosphate groups were involved in the biosorption process. X-ray photoelectron spectroscopic studies on the bacterial cells interacted with Cr(VI) confirmed the presence of both Cr(VI) and Cr(III) on the cell surface. The electrokinetic studies revealed that the surface potential of the bacterial cells were less electronegative subsequent to interaction with Cr(VI), compared to the cells alone, which further testified to the binding of positively charged Cr(III) ions, formed by bioreduction of Cr(VI), to the bacterial cell surface. A marginal shift in the iso-electric point obtained for the bacterial cells interacted with Cr(VI), corroborated the involvement of chemical binding forces in the bioremediation process.

Jan 1, 2016

By A. R. Sheik, A. A. Baba, M. K. Ghosh, K. Sanjay, R. B. Bale, A. G. F. Alabi, F. A. Adekola, L. Ibrahim

"This paper studies the characterization and dissolution of a Nigerian pyrolusite ore, reporting the results of ore physicochemical analyses and detailed ore characterization before and after leaching at optimal conditions. Ore dissolution rate increased proportional to acid concentration and temperature, but decreased with ore particle size. In a 4 M H2SO4 solution at 80°C with a particle size of –90+75 µm and moderate agitation, ore dissolution rate reached 78.7%. Unleached residue produced under optimal leaching conditions consisted of silica with admixtures of cristobalite and stishovite. The calculated activation energy supported the proposed diffusion control mechanism for the process.RÉSUMÉ Le présent article étudie la caractérisation et la dissolution d’un minerai de pyrolusite du Nigeria, il donne les résultats des analyses physicochimiques du minerai et de la caractérisation détaillée du minerai avant et après la lixiviation sous des conditions optimales. Le taux de dissolution du minerai augmentait proportionnellement à la concentration de l’acide mais décroissait avec la taille des particules. Dans une solution 4 M H2SO4 à 80 °C, avec une granulométrie de –90+75 µm et une agitation modérée, le taux de dissolution du minerai a atteint 78,7 %. Les résidus produits sous des conditions optimales de lixiviation étaient constitués de silice avec un mélange de cristobalite et de stishovite. L’énergie calculée d’activation supportait le mécanisme de contrôle de la diffusion proposé pour le procédé."

Jan 1, 2016