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By Serena Biella

Gold has received a growing interest as a catalyst for the selective oxidation of organic molecules using oxygen under mild conditions1. In the liquid phase application small gold particles (2.5-7 nm) deposited over different solid supports can be used but, like many other noble metals, their catalytic activity depends upon the nature of the support and the preparation metod2-5. In particular, gold on carbon is the preferred catalyst for the oxidation of the alcoholic 2-7 and the aldehydic7-9 groups and one of the best preparation method is the immobilisation of colloidal particles2-5,8,9. Suggested application of gold catalysis in fine chemicals production, tested on laboratory scale preparations, is reported in table 110. In order to produce more efficient catalysts for the liquid phase oxidation and to derive new insights into the reaction mechanism, we have made a comparison among catalytic systems based on different metals. The first effort was to test the activity, if present, of naked metal particles and then to study the influence of various materials commonly used as a support.

Oct 1, 2003

By B. Zhu, W. E. Lee, N. Li

Al powder is used extensively as an antioxidant in carbon-containing bricks, but it cannot be used directly in water-based carbon-containing castables due to its hydration tendency. To overcome this problem, in this work, SiO2-PVA (polyvinyl alcohol) inorganic-organic hybrid coatings have been prepared via sol-gel processing, and used to coat Al powder. The hydration behaviour of uncoated and coated Al powders has been investigated in water at 60 or 100°C for 36h by examining phase and microstructural changes. While significant hydration is detected in uncoated Al powder, no obvious hydration is detected in coated Al powder, indicating that its hydration resistance has been greatly improved. Oxidation resistance of graphite coexisting with uncoated or coated Al powder was also investigated in air at 1250°C for 1.5h. The oxidation ratio of graphite coexisting with coated Al powder was similar to that of graphite coexisting with uncoated Al powder, indicating that both powders showed similar antioxidising behaviour. This, along with the much improved hydration resistance, makes the coated Al powder a potential antioxidant in carbon-containing castables systems.

Jan 1, 2004

By J. F. Harkom

Introduction The importance of the preservative treatment of mine timbers need scarcely be stressed here. Increasing the life of mine timbers will reduce one of the major costs of mining and also conserve the available timber supply which lies within easy access of the mines. When treated, several species of timber may be used which otherwise could not be considered, owing to their short life. Another feature which should appeal to the mining industry is that wood preservatives are a mine product, and the benefit to be derived from the increased consumption of wood preservatives due to the example set by mine owners is not inconsiderable. Mine timbers may be divided into three classes when considering preservative treatments. (1) Timber obviously not profitable to treat owing to long natural life or short period of time in service. (2) Timber that obviously should receive protection from decay. (3) Timber installed in locations where the length of service required will depend on future developments, so that preservative treatments might or might not prove to be a profitable investment.

Jan 1, 1930

By B. Loveday, G. W. Delaney, S. Cummins

"Applying DEM to prediction of tumbling mill performance is challenging because several different modes of breakage are active in the process. As our knowledge of breakage and computational capacity improve, it is worth revisiting previous simulation tasks which did not produce a satisfactorily realistic description of a measured process. At SAG 2006, we reported the simulated and measured outcomes of treating a well characterised ore in a 1.2 m diameter mill. This well instrumented, pilot scale mill at the University of KwaZulu-Natal has been combined with some new approaches to ore testing to allow different modes of breakage to be tested. The mill design allows the rate of generation of fine material to be measured in close to real time for autogenous and SAG mill charges. The updated simulation model estimates mass loss with particle evolution and embeds the cumulative damage and breakage.The simulated results are compared with the measured results. Issues such as relating modelling inputs to particle breakage characterisation data and the accuracy of the predictions of the models are discussed."

Jan 1, 2012

By P. Wanjara, M. Xiao, M. Jahazi, C. Poon

Using a robotic 4kW Nd:YAG-laser system, Inconel 718 (1 mm sheet) was welded with and without filler wire to investigate the effect of processing parameters, including power input and welding speed, on the weld geometry, microstructure and mechanical properties. By means of both nondestructive testing and microscopic examination, the weld quality was studied to determine the nature of the welding defects (porosity, cracking and bead shape) over the processing range of 3-3.5 kW for the power input and 4.5-6 m-min-1 for the welding speed. Application of the design of experiment methodology permitted the examination of the relationship between the process parameters and mechanical properties, from which the optimized laser welding conditions could be determined for joining Inconel 718. In particular, the research results indicate that Nd:YAG-laser welding technology can achieve defects free, mechanically sound welds with narrow fusion and heat effected zones.

Jan 1, 2006

By Robert A. Creaser, Iain Mitchell, Robert L. Linnen

Abstract - The Bermuda Zn-Pb showing is hosted by dolomitized Blue Fiord Formation of Devonian age, located east of the Ensorcellement dome on the Grinnell Peninsula of Devon Island. Fluid inclusions in hydrothermal calcite indicate that the mineralization precipitated from low-temperature, highly saline brines. The ?34S compositions of sphalerite, galena, and marcasite range from 16.1‰ to 35.2‰. Consequently, the Bermuda showing is interpreted to be Mississippi Valley-type (MVT) mineralization. The apparent age of mineralization has been determined by the Rb-Sr method from sphalerite separates, and a Late Devonian age of 357 ± 50 Ma (MSWD=65), with an initial 87Sr/86Sr ratio of 0.7083 ± 0.0020 is indicated. This date, within error, is the same as the Polaris deposit. This suggests that the mineralization formed during the Ellesmerian Orogen, although it is also possible that mineralization is associated with extension, related to the opening of the Sverdrup basin. The strontium and sulfur isotopes and fluid inclusion analyses indicate the involvement of a brine that acquired its salinity from interaction with evaporites, lower in the stratigraphic succession. The Polaris mine is the type deposit in the Cornwallis Zn-Pb district and is hosted by the Thumb Mountain Formation. The results of this study are significant because they demonstrate that regional brine movement is more widespread than previously recognized, and that MVT mineralization in the Cornwallis Zn-Pb district is not restricted to the Thumb Mountain Formation.

Jan 1, 2004

By Bo R. Arvidson

"New permanent magnetic alloys have recently opened up possibilities for development of unique mineral separators. These are now making several new applications feasible. In many cases where conventional electromagnetic-induced roll separators have traditionally been used, the new permanent magnetic roll separators may reduce both over-all capital costs and operation costs.The development of the next generation of extremely powerful permanent magnets, i.e. neodymium-iron alloys, is progressing rapidly and will affect the roll separator as well as another type of magnetic separator. Permanent Magnet Roll SeparatorDesign and FeaturesDiscs of permanent magnets interleaved with soft iron discs constitute the basic magnetic roll design (Fig. I). By enveloping the magnetic roll with a thin abrasive resistant belt (Fig. 2), even highly magnetic particles are removed.The first prototype roll utilizing the new magnets was shown to have approximately equal strength as induced magnetic roll (IMR) separators. Since the initial test roll, the new separator, called the PERMROLL® , has been made twice as strong with regard to magnetic force, that is, the magnetic flux density is determined to exceed 1.7 tesla (17 kilogauss), while the magnetic field gradient is more than twice the gradient than can be practically achieved with IMR."

Jan 1, 1985

By Adrianus (Adrian) Halim, Tomas Bolsöy, Stina Klemo

"This paper describes the ventilation system used in underground hard rock mines in Sweden and Finland, which is very different than the system used in other major mining countries such as Australia, Canada, South Africa, and USA. The system utilizes auxiliary fans with Variable Speed Drive to distribute primary airflow to working levels instead of regulators that are commonly used in other countries. Descriptions about Ventilation on Demand in this system and ventilation regulations in Sweden and Finland are presented in this paper. This paper also quantifies a comparison between the Nordic and the system used in other countries. KEYWORDS Auxiliary fan, Regulation, Ventilation on demand (VOD), Variable speed drive (VSD) INTRODUCTION The primary objective of an underground mine ventilation system is to provide sufficient airflow to dilute atmospheric contaminants that are produced by mining activities. Typically, a mine ventilation system consists of one to four primary fans, regulators to control primary airflow distribution to levels or panels, and auxiliary fans that distribute airflow to dead-end workings via ducts. Depending on circuit geometry, underground booster fans are sometimes used. This system is widely employed in many countries such as Australia, Canada, USA, United Kingdom, and South Africa. However, mines in Nordic countries such as in Sweden and Finland employ a different system, in which auxiliary fans instead of regulators are used to control primary airflow distribution, as well as distributing airflow to dead-end workings. This paper describes the general layout of Nordic ventilation system, its VOD and heating system, its comparison with the system that is widely used in other countries which is referred as “Non-Nordic ventilation system” in this paper, and the current ventilation regulations in Sweden and Finland. The comparison was quantified by doing simulations using Ventsim Design 5 software. DESCRIPTION OF NORDIC VENTILATION SYSTEM General System Layout Figure 1 shows a schematic of typical ventilation system used in Swedish and Finnish mines. The schematic was drawn by Franzen, Myran, Larsson, and Rustan from Stiftelsen bergteknik forskning (Swedish Rock Engineering Research Foundation) and the English translation is written next to the Swedish terminologies. The system is generally a push-pull system. None of Swedish and Finnish mines use exhaust system. As shown in Figure 1, the primary airflow is distributed to levels by auxiliary fans that are bolted to a bulkhead located in the access to intake raise/shaft. These intake fans are attached to ventilation ducts that distribute airflow to all working faces. The exhaust auxiliary fans, which are not attached to any ducts and also are bolted to a bulkhead located in the access to exhaust raise/shaft, then flow the exhaust airflow into the exhaust shaft. A small quantity of this exhaust air is directed into the ramp, which acts as another main exhaust airway. The deepest level is also equipped with booster fan(s) that draw air from the intake shaft/raise and direct it into the ramp to provide fresh air in the ramp. There is no free split in this system. Figure 2 shows a schematic of a level ventilation layout in the Nordic system. Figure 3 shows a photo of these auxiliary fans."

Jan 1, 2019

By Donald F. MacDonald

WE are living in a mineral and technological civilization. The Encyclopedia Britannica defines civilization as follows: "It is the final test of a progressive civilization that a given effort shall produce a larger modicum of average individual comfort, and the pursuit of this ideal has been from first to last the impelling force which drives civilization onward". This "individual comfort" demands labour-saving machines and devices such as motor cars, radios, and thousands of other inventions, most of which require minerals and metals in vast quantity for their manufacture. In fact, more minerals and fuels have been used in the last third of a century than in all previous world history. Since 1800, the world's production of metals has increased more than a hundred fold (1). Scientific discovery is now advancing on a wide front, thanks to the research work that is being carried on in progressive countries. The world's work is now being done with very much less human drudgery than in the past. We do not have to toil for our living as our ancestors did, even if we follow their occupations. The average man has had many years added to his life-span, but, apparently, little to his spiritual stature and less to his common sense.

Jan 1, 1939

By N. Morrison, E. J. Rogans, A. J. Macintosh, N. Schoeman

"The design of carbon-in-pulp (CIP), and carbon-in-leach (CIL) adsorption circuits has essentially remained unchanged since the early days of the carbon process for gold recovery. For CIP circuit the pulp residence time is traditionally fixed at one hour per contactor with a carbon concentration of between 15 and 20 grams per litre, and the counter current carbon transfer rates are in the region of 15% pulp recycle. For CIL, the pulp residence time is usually three hours per contact or, with lower carbon concentrations ( 5 to 10 grams per litre).The drawbacks of using the counter current CIP/CIL adsorption circuits are discussed using modeling developed for CIP/CIL plant design. Counter current CIP/CIL, circuits are then compared with the carousel method of adsorption circuit design.The use of equipment suitable for the carousel approach is discussed which is, the AAC cylindrical and pumping (MPS) screens, the AAC pump-cell plant and launder designs.Finally, two plants at the Vaal Reefs Gold Mining and Exploration Company that use carousel adsorption circuits, namely the Vaal Reefs No. 1 Gold Plant, a CIL plant with stepped contactors, and the Vaal Reefs No. 2 Gold Plant, a CIP using a very short residence time (AAC pump-cell) are discussed."

Jan 1, 1998

By M. Mahdi, L. So, A. MacMillan, D. Metcalfe, J. Woloshyn, D. Sauter, N. Uys, JP. Janse van Rensburg

For city smelters, with limited real estate, efficient slag cleaning furnaces followed by water granulation to produce an iron silicate product is the preferred process approach. Water granulation, however, consumes large volumes of water and requires high maintenance due to abrasive slag/water slurries. Air granulation offers an alternative to water granulation, which eliminates water use and has low maintenance requirements. Although full-scale operation has not been implemented for copper slags, full-scale operation for platinum group metal (PGM) converter slag has been implemented. A review of full-scale air granulation performance for PGM converter slag is provided. Based on PGM converter slag granulation performance, parallels to copper slag granulation are drawn and full-scale operation for copper slag is modelled using computational fluid dynamics (CFD). INTRODUCTION Typical slag management practices in the copper industry include dumping, slow air cooling, and water granulation, as shown in Figure 1. Dumping is the most commonly used slag handling method for most metal production plants, but presents challenges including the requirement for a large slag pit, requirement for expensive/high-maintenance “hot” mobile equipment, risks associated with transportation of molten slag, and no value recovery from slag as a sellable by-product or from slag as a source of heat.

Jan 1, 2019

By Stanley Davidson

"This description of the structural geology of the Beattie mine has been condensed from a more comprehensive paper published previously (4).The property is in western Quebec, a short distance east of the Ontario boundary on the extension of the so-called Porcupine belt into Quebec.According to the geological surveys of the Dominion and Provincial Governments the regional structure in the vicinity of the mine is an easterly pitching, overturned syncline with several thousand feet of Timiskaming sediments in the centre surrounded by Keewatin volcanics (1, 2, 3).The mine lies on the north limb of the syncline, and the Keewatin series in this locality is, with few exceptions, overturned, dipping steeply north and facing south.The mineralization is closely related in space, and possibly genetically, to a body of syenite porphyry intruded into the Keewatin series along the north limb of the syncline. No ore has been found very far from the syenite or related lath-porphyry dykes, and the largest orebodies are composite, consisting of bleached and brecciated volcanics ( primarily tuffs) adjacent to altered syenite porphyry, both silicified and mineralized with very fine pyrite and arsenopyrite. In addition there are important ore shoots following a fracture zone within the syenite."

Jan 1, 1954

By Brock Morrison, Bernt Ling

"The Kiruna Electric System is an all electric ramp haulage system developed for underground mining. This electric truck haulage system is currently operating on three continents. This paper will review the technology of the system, existing installations as well as the economical benefits to the mining industry. The system was designed and developed to extend and exploit the economical advantages of ramp haulage. Performance information is provided. IntroductionThe Kiruna Electric System has been the subject of a number of technical papers over the past sever al years. During that period, the content of the presentations has changed from concept and theory to prototype testing to description of installed and operating systems.The intent of this paper is threefold:1. to present a brief review of the technical features of the Kiruna Electric Systems;2. to review the existing installations with performance data; and3. to provide a description of on-going developments within the Kiruna Electric Program during 1991.The Kiruna Electric is a high capacity ramp haulage system for underground mining operations due to an All-Electric Drive System, including two heavy duty electric traction motors. The high capacity of the K1050E results from three factors:• payload - 50 tonne• speed - 18 km/hr to 20 km/hr up a IS0J0 ramp (total resistance)• availability - over 90010 during a 12-month period"

Jan 1, 1991

By C. Diaz, S. W. Marcuson, K. I. Burgess

Deep roasting in fluid bed roasters is the first unit operation in Inco&apos;s "roast-reduction smelting" process for the treatment of nickel sulphide concentrates. The roaster product, a low sulphur calcine, is reduction smelted with coke in an electric furnace to yield a sulphur-deficient matte which is then converted to low (<1%) iron matte in Peirce-Smith converters. Due to the deep roasting, a minimal amount of sulphur dioxide is evolved in the smelting and converting stages. Sulphur is eliminated from the concentrate almost exclusively in the roasters in a single, continuous, strong, gas stream suitable for treatment in an acid plant. This paper discusses the commercial scale testing of deep fluid bed roasting of nickel concentrate at Inco&apos;s Thompson Smelter as part of two commercial scale campaigns on roast reduction smelting conducted in 1981-1982. Slurry feeding, practised during the second campaign, permitted excellent control of the air/concentrate ratio in the roaster and, in turn, good control of sulphur elimination (about 80% of input). Smooth autogenous operation with high oxygen efficiencies (about 95%) was promoted by operating at bed temperatures of830°C to 850°C with calcine recycle. High throughputs and the desired metallurgy were achieved. The extensive testwork conducted during the two experimental RRS campaigns demonstrated thot deep fluid bed roasting of nickel concentrate at high oxygen efficiency is a technically viable operation.

Jan 1, 1994

By Robert S. G. Chapman, Kieran M. J. Downes

The Sulphide-Preview Lakes area is located 45 km northeast of La Ronge in northern Saskatchewan. It lies within the southern portion of the Proterozoic La Ronge Volcanic-Sedimentary Belt. Two styles of gold mineralization are present in the Sulphide Lake area , stratabound gold mineralization is intimately associated with a pyrite-pyrrhotite-arsenopyrite-bearing graphitic argillite unit within a sequence of intermediate to felsic volcaniclastics. Past operators established three mineralized zones along this horizon with combined reserves for two of the zones, of about 175,000 tons at 0.22 oz/ton Au. In the Preview Lake area , gold mineralization occurs in variably sheared gabbro/quartz diorite sills within a mixed sedimentary-felsic volcaniclastic sequence. Gold occurs with arsenopyrite, pyrite and minor chalcopyrite associated with quartz veins and stringers. A sulphidebearing graphitic argillite unit occurs in close proximity to the mineralized shears. Past operators delineated seven mineralized shear zones, two of which were drilltested. Average gold grades reported are in the 0.1 to 0.2 oz/ton range with erratic values up to 5.0 oz/ton.

Jan 1, 1986

"ChairmanThis part of the discussion is intended as an exchange of information between those who have installed rubber liners in their mills and a means of others to get information that may help them decide if rubber liners would be applicable to their mills.To start the discussion and to relate it to the previous section of this symposium Mine Equipment Co. Ltd. have supplied some graphs that will give some idea of the noise suppression that may be expected from the u.se of rubber liners instead of steel. The figures used in preparing the graphs came from installations of rubber liners in Sweden.L. Strah - Mine Equipment Co.The graph, Figure 1, shows on the bottom the octave band range. The noise level generated by the steel liners is represented by the dotted line and lies within the shaded area where it is considered that hearing damage may result. The solid line represents the noise level generated by rubber liners in the same mill and you will see it is below the shaded area. Although it is not marked on the graph I think the decibel range is from 7 5 to 115. The next one, Figure 2 which shows the relative noise levels generated by steel balls and pebbles with both steel and rubber liners shows the decibel range."

Jan 1, 1968

By N. Verbaan, Ph. Henry, S. Lamotte

Hydrometal(lurgy) provides an adequate technology to reintroduce otherwise lost metal units into the industrial cycle, thereby saving resources and energy, while keeping the environment cleaner. Three case studies at an integrated hydrometallurgical recycling facility (Hydrométal) in Belgium are discussed. (1) Non-ferrous leach residues are treated by a leach-SX process to recover their minor metals (Ge) contents. The remaining acid waste solution is used by the fertilizer industry nearby. (2) Residual low quality acid and caustic are used in the processing of zinc industry cements to produce copper, nickel, cobalt and zinc concentrates by several consecutive selective leach - precipitation processes. (3) Copper anode slimes are treated and their precious metal contents are recovered. Depending on the composition of the slimes, separate or combined concentrates of copper, bismuth, tellurium/selenium and silver/precious metals can be produced.

Jan 1, 2004

By E. J. Marcotte

"BRIEF DESCRIPTION OF GRINDING CIRCUITCrushed ore at -5/ 16 in. is delivered by a conveyor system from the crushing plant to two 1250 ton fine ore bins. The ore is transferred from each bin by a 30 in. feeder conveyor belt, operated by a Link Belt P.I. V. (variable speed) drive, to a 24 in. conveyor that feeds the 8 x 10 Allis Chalmers rod mill.The rod mill discharges to a common mill discharge pump box. Three 6 x 6 SRL pumps are employed to pump the combined mill discharge pulp to a common distributor box which distributes the feed to two of the three Kreb D lSB cyclones in each of the two banks at a hydraulic pressure of 6 psi.The cyclone overflow at a specific gravity of 1. 25 (i.e. 32% solids) is transferred by gravity to two revolving chip screens for wood chip removal and from there to a pump box. Two 5 x 5 SRL pumps feed the pulp to the thickeners. The underflow from the cyclones is fed to two 8 x 8 Allis Chalmers ball mills which discharge to the common mill discharge pump box. Thus, a closed circuit is formed between the ball mills and their respective bank of cyclones. The circulating load as most recently calculated is 262%."

Jan 1, 1966

By A. Lemay, G. Morin, C. Desmeules

"Incorporated in 1976, Sidbec Normines was mandated to exploit a deposit of specular hematite at Fire Lake. A combined effort of three companies, Sidbec, which holds 50. 1 % of the actions, British Steel Corporation another 41.67 % and finally Quebec Cartier Mining, a subsiduary of U.S. Steel Corporation, with still another 8.23 %.The deposit is located 60 miles north of the town of Gagnon. The extracted ore is crushed, in a giratory crusher, to-8 11 chunks, and from there, it is transported, by rail, to a concentrator at Lac Jeannine.A concentrate containing 65.5 % Fe and 5.5 % Sio2 is produced, using conventional methods like autogeneous mil ls and spirals. The concentrate is then transported by rail to the Port Cartier installations.The installations in Port Cartier include a secondary concentrator, a pellet plant, and stockpiling facilities for pellets and concentrate. The pellet plant has two product lines in paralel, producing a total designed tonnage of 6 millions tons of iron ore pellets, of which 3mi11ions tons are used in direct reduction furnaces.The secondary concentrator is designed to remove a portion of the silica contained in the ore, usually less than 2 % Si02 should remain from the original 5.5 % Si02 in order to produce iron ore pellets which are well suited for use in direct reduction and electric furnaces."

Jan 1, 1981

By W. Beres, Li. J.

The finite element method (FEM) has been applied to investigate the stress fields and deformation of a TiN/Ti-6A1-4V coating/substrate system subjected to nanoindentation. MSC Patran and MSC Marc were used to prepare the three-dimensional finite element models and to perform the simulations of the Vickers nanoindentation experiments. Pure silicon and TiN/Ti-6A1-4V coating/substrate system were analyzed. The properties of the materials were assumed to be homogeneous and isotropic with a linear hardening behavior. The reverse method was used to extract material properties, such as the yield stress and strain hardening coefficient, from the numerical results by comparing the simulated indentation load vs. penetration depth (P-h) curves with those obtained experimentally. Both non-linear elastic and non-linear elastic-plastic analyses were carried out for the coating/substrate system. The results are given for four different coating thicknesses.

Jan 1, 2004