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By B. Dubreuil, J. -M. Lalancette, D. Lemieux, C. Chouinard

The extraction of gold and silver has been examined via the use of mixed halogens: chlorine and bromine. The reaction was performed in a brine of sodium chloride with a small amount of sodium bromide at 40-50°C, in an atmosphere of chlorine, at atmospheric pressure. The process takes advantage of the very high reactivity of bromine towards gold, while the higher oxidation capacity of chlorine leads to gold chloride as end product with recycling of bromine. Fast reaction rates are observed along with gold recovery at the level of 95%. Chlorine-consuming common elements are removed prior to chlorination.

Jan 1, 2011

By A. Gakwaya, K. Ba, M. Guillot, J. Levesque

"In the aerospace industry, parts requiring tight dimensional tolerances and high mechanical properties are often produced by forging. This forming process allows for an optimal use of the material and can produce high quality parts at a reasonable cost. Thanks to CAD techniques, it is now easier to predict flow profiles and in-process defects occurrence as well as wear of the forging dies. However, in order to determine the properties of the forged part with computer simulation methods, a good material constitutive law is a prerequisite. This paper presents a virtual manufacturing process modeling for the closed die forging of a workpiece performed with Abaqus. The hot closed die forging is a regular process applied to manufacture metallic components used in aerospace industry. In this forming process, the material flow and final properties depend on the microstructure evolution during the process that is why it is important to include the microstructure effects in the material model. Based on the stress-strain data measured experimentally, the material parameters of the standard (classical) Johnson-Cook constitutive model and of a modified Johnson-Cook constitutive law including the microstructure effects have been determined. The obtained simulation results are compared with the experimental results for validation.INTRODUCTIONDue to their good physical and mechanical properties such as ductility, fatigue strength, corrosion resistance and rupture, aluminium alloys are often used in the aeronautic and the automobile industries. In this work, we present the forging of an Al-Zn-Mg-Cu alloy, a high strength aerospace alloy recognized for his good combination of physical and mechanical properties. The forging process is simulated in Abaqus Explicit using both the standard Johnson-Cook law (Johnson & Cook, 1983; Hor, 2011; Lin et al., 2012), and its modified version as proposed by Andrade et al., (1994). The Johnson-Cook law offers the advantage of considering the coupled effect of the plastic strain, the plastic strain rate, the temperature of forging and the hardening effect. However, it is a phenomenological model which does not account for the effect of the microstructure evolution. In this work, a modified Johnson-Cook model implemented in a user subroutine is used. It includes the effect of the dynamic recrystallization phenomenon during the hot deformation. The dynamic recrystallization has a noticeable influence on the microstructure and on the properties of the material. The term dynamic means that the process starts and acts during the deformation and this is different from the static mechanism of recrystallization which occurs during an annealing and after cold or hot deformation. Since properties of the alloy used in this work are not readily available in the literature then characterization tests have been done at various temperatures and strain rates, in order to determine the thermomechanical properties and the material behavior during the process of hot forming, more precisely during the hot forging process."

Jan 1, 2016

By G. Hu, P. Chang

"As hydraulic fracturing is forbidden in some countries due to its accompanying environmental pollutions, microwave fracturing was proposed as a substitute technology to enhance coal seam permeability. Its mechanism includes: on the one hand, thermal stress caused by non-uniform microwave heating leads to fracture development in coal body, which increases coal seam permeability for gas; on the other hand, moisture within the coal body that hinders gas desorption and diffusion is removed during this process. To study the effect of moisture content on fracture development under microwave irradiation, high resolution photographs were taken before and after microwave treatment. These photographs were then binarized and skeletonized. Based on the processed photographs, the total area were calculated using ImageJ. The results showed that coal samples with 0% and 25% water saturation have more variation in fracture development as compared to that of samples with 50%, 75% and 100% water saturation. This study can be very useful in gas drainage and gas control in coal mines. INTRODUCTION Coalbed methane (CBM) is a clean energy source as well as a natural hazard to underground mining (Kurnia, Sasmito, & Mujumdar, 2014; Ranathunga, Perera, & Ranjith, 2014). One of the main goals of mine ventilation is diluting methane and removing underground contaminants (Xu, Huang, Nie, Chalmers, & Yang, 2017). Coalbed methane (CBM) has to be extracted prior and during underground mining to avoid methane outburst and explosion accidents. However, with the increase of mining depth, the coal permeability decreases significantly, which makes it hard to extract the methane (Huang, Xu, Hu, Kizil, & Chen, 2018). To enhance the coal seam permeability, many CBM recovery methods have been applied on-site, such as hydraulic fracturing and enhanced coalbed methane (ECBM). However, hydraulic fracturing is restricted due to environmental concerns and ECBM is only suitable for the coal seam with relative large permeability (Bustin, Bustin, Chikatamarla, Downey, & Mansoori, 2016; Huang, Xu, Chen, & Chen, 2018; Huang, Xu, Hu, et al., 2018)."

Jan 1, 2019

By M. Sahoo, P. Burke, Y. Fasoyinu, J. P. Thomson

The effects of grain refinement, mold temperature and chemical composition on the hot tearing resistance of aluminum alloys 535.0 and 206.0 has been studied by pouring constrained rod castings in metal molds. In addition, two prototype components that could be used in automotive applications were also poured from both alloys by gravity tilt-pour and low pressure permanent mold casting processes. This paper summarizes the results and issues encountered during the casting trials. It was shown that grain refinement and mold temperature ::::: 400°C reduced, and sometimes eliminated hot tear cracks in both alloys. The two prototype engineering components could be cast successfully from both alloys in metal molds. The metallurgical issues related to molten metal treatment and processing temperatures were well controlled. However, issues related to the control of hot tearing, casting and mold design must be addressed in future studies to guarantee the production of defect free castings.

Jan 1, 2006

By J. I. Gazzarri

A model of solid oxide fuel cell AC impedance behaviour has been developed and is used to simulate the frequency response of a single cell with and without mechanical damage. The results indicate that the presence of mechanically induced damage within the components of a solid oxide fuel cell can be detected by comparing the frequency response of the undamaged cell with that of a cell in which in-plane cracking or delamination has occurred. The presence of such defects manifests itself as a new semicircle in the Nyquist impedance diagram of the full cell. A parametric study reveals the resolution capabilities of the method in terms of the geometrical characteristics of the defects.

Jan 1, 2005

By E. C. Goodhue, R. D. Coleman, I. E. Puddington, A. F. Sirianni

Iron ore samples containing apatite are fractionated to acceptable products by spherical agglomeration methods. The phosphorus is upgraded by a factor of 10 at an elevated pH. High-grade iron products are obtained in good yields from the tailings in a second step of the operation. The grade of the phosphorus separated appears to reach a maximum at about pH = 10; recovery of iron decreases below about pH = 4. Both the recovery and grade of iron are found to be reduced sharply above about pH = 8.

Jan 1, 1968

By R. A. (Dick) McIvor

"It is important to ensure that the basic mine hoist plant design fundamentals are incorporated into any new mine hoist plant project before detailed design engineering is commenced. Some of the basic design fundamentals to be considered are: hoist rope fleet and flight angles for good hoist rope coiling, hoist rope harmonic frequency study to ensure that the hoist rope does not run at full speed at a rope resonance frequency, head frame and shaft clearance diagrams to establish the optimum positions for the loading and dumping of the shaft conveyances, access in the head frame and shaft collar for hoist rope and shaft conveyance installation and removal. Failure to consider the hoist plant fundamentals before detailed engineering commences will result in extra costs for hoist plant redesign or a significant increase in operating and maintenance costs for the mine due to increased hoist plant downtime to perform tasks and a lower mine operating efficiency. INTRODUCTION The mine hoisting plant is the most critical single line component in the operation of a shaft sinking operation or a permanent installation. Bad decisions in the design and selection of the hoist plant equipment can significantly add to the operating costs and up-time in the operation of the mine. Mine hoisting plant equipment installed costs represent approximately 5 to 8 percent of the capital cost of a new mine, yet price sometimes becomes the deciding factor for procuring the hoist plant components, sometimes selecting used equipment that may compromise the design and maintainability of the mine hoist plant. Mine downtime can cost upwards of $100,000 per hour and it will not take a very long time to eat up all the so-called savings on hoist plant equipment purchases. This paper will provide guidelines for the design, selection, installation and maintenance of mine hoist plant equipment with the objective to having the right mine hoist plant with the highest operational availability and best maintainability. PRELIMINARY DESIGN INFORMATION Before any engineering commences, the following information needs to be obtained to allow the preliminary sizing of the hoist plant equipment: • Shaft depth: The shaft depth will influence the hoist rope selection based on the material and personnel loads anticipated for the mine design. The shaft depth will also influence the maximum speed of the shaft conveyances. • Annual production: The desired annual production will influence the required payload sizing with allowances for maintenance and inspections of the hoist plant equipment."

Jan 1, 2019

By Vladislava A. Ignatkina, Victor D. Samyguin

"Within the limits of two-phase approach, considering mass transfer with pulp and air streams was shown that each bubble appears to be an elementary carrier, transporting particles from the collection zone into the froth. The kinetics of flotation was described by the exponential equation in which first order flotation speed constant has to be replaced with two-phased coefficient of a mass transfer. Criteria of selectivity of two ore fractions separation, based on determination of optimum time at which maximum difference between extractions and components content in separated fractions were offered. An interrelation between optimum time of pulp residence in a flowing chamber of a flotation machine, time of bubbles mineralization and an optimum airflow has been ascertained. Cumulative criterion of mass transfer efficiency of flotation process has been ascertained to be a form of the spectrum and its position on axis of three-phase coefficient of a mass transfer.INTRODUCTIONRegularities of a mass transfer of three bearing streams: pulp stream, air stream and froth stream underlie theory of mineral complexes flotation (Samygin, Filippov, & Shekhirev, 2003)However, only description of mass transfer in pulp stream by means of kinetic equations that were simple and convenient for practical use, has gained a full distribution (Tykhonov, 2009;Rubinstein&Filippov, 1980; Saleh, 2010).Within the limits of a single-phase approach, the role of gas stream in increase of speed and selectivity of flotation, was associated with an improvement of hydrodynamic mode. An influence of particles and bubbles sizes (Rubinstein&Filippov, 1980; Rubinstein&Samygin, 1998, Samygin et al., 2003; Dai, Fornasiero,& Ralston, 2000), of pulpflow and airflow (Finch& Dobby, 1990) and turbulent energy intensity (Shubert, 1979; Massinaei, 2007) on the flotation process has been studied. It was stated that flotation selectivity is increasing by means of gradual airflow increase from first to final cameras of the impeller flotation machine (Aslan&Boz,2010; Finch, 2011) and by means of using a multizone flotation machine (Samyguin, Filippov, Matinin, Lekhatinov, &Tertyshnikov, 2013)."

Jan 1, 2016

By A. Taylor

This paper considers mineral processing in zero gravity dry environments typical of asteroids or comets. The electro-dynamic separation technique using pneumatic flow systems is explored. Pneumatic delivery of solids is used because of extreme temperature changes and the possible scarcity of water. The present earth-based process and how it can be modified for these conditions is examined.

May 1, 2001

By Roger Potvin

Abstract The demand for pure zirconium and titanium metals in Germany increased considerably during the war. Pure zirconium was used in flash bulbs, in vacuum tubes, and in time fuses for bombs, where it has a decided advantage because it gives no gas in burning. Under the form of alloy, it was used with other rare elements for making substitutes for platinum; it was also used as a scavenging agent in high-grade steels. Metallic titanium was mainly used in connection with the manufacturing of special alloys. The authors were sent to Germany by the Department of Reconstruction and have investigated the German process developed for producing these rare metals. They describe the procedure and special equipment used for their commercial production in Germany during the war. General Metallic zirconium and titanium were .produced on a commercial scale in Germany by the thermal reduction, with metallic sodium, of potassium fluozirconate and titanium chloride, respectively, using a mixed potassium and sodium chloride flux. According to the information gathered, the sole German producer of these rare metals in pure form was the Deutsche Gold und Silber Scheideanstalt (commonly called Degussa), at their Werk II, 215 Gutleutstrasse, Frankfurt/Main, which was visited by the authors on September 18th, 1945. As far back as 1934, Degussa was carrying on active research on the manufacture of zirconium, and nearly one ton of the pure metal had been produced before September, 1939. Concurrently, a quite similar process was worked out for the recovery of titanium and it was in commercial operation in the year 1938, during which the production totalled about half a ton (metric). The demand, especially for pure zirconium, increased considerably during the war, attaining a total of about 48 tons during the period October, 1939, to the end of 1944, and reaching a peak of more than 15 tons in 1943. In 1944, the plant was slowed down due to the frequent and disastrous bombing by the Allies, especially in March and September.

Jan 1, 1946

By Lloyd Buckingham

"The operating cost of a gold mine employing granular activated carbon to recover gold can be greatly affected by the condition of in-circuit carbon and its attrition losses. To accurately identify and quantify carbon losses requires careful study. Carbon attrition in the mill can be attributed mainly to physical or mechanical breakage due to the transfer of carbon in the circuit and to carbon oxidation and thermal fracture occurring in the carbon reactivation kiln. Of the equipment involved in carbon transfer, the water powered eductors are the major cause of abrasion and should be replaced with pumps or alternate methods that can serve the purpose. This paper also reviews the impact of carbon stripping and washing on overall operations.IntroductionHolt-McDermott Mine operates a 1360 tonnes per day Carbon-in-Leach (CIL) mill to recover gold. The relatively high carbon consumption and high remaining gold values on carbon after stripping were viewed as a challenging project for research. Extensive metallurgical testwork was initiated to reduce these values. Figure 1 below indicates the carbon flowchart prior to any significant changes in the carbon handling procedures.Carbon consumption after commissioning which was as high as 10""/o of carbon eluted, has been brought down to less than 5%. Changes that brought about this 50% reduction in carbon consumption are:1 ) Improvements in kiln operation2) Elimination or replacement of eductors3) Reduction in tonnes of carbon eluted"

Jan 1, 1994

By Donald F. MacDonald

METAL PRICES RISE WITHIN the past nine months, the mining industry of the world has been revivified by a spectacular price advance for the metals. ln fact, practically all geological raw materials have been marked up during this period. Reviving industry started the price rise, but the armaments race among the nations has intensified it. These factors, coupled with our decided building shortage, which must be made up, will probably maintain metal prices at decidedly favourable levels over the next two or three years, or longer. OUR MINERAL CIVILIZATION It is interesting to recall that in the past hundred years, while the white population of the world increased some three ta three and a half fold, the consumption of minerals increased seventy-five fold. In other words, ours is a mineral civilization. If we disregard short slumps, which we will occasionally experience, it seems certain that the bread upward trend in mineral consumption will be maintained for many decades into the future. Nations without reasonably abundant and diverse mineral deposits will eventually become nations without much power. Canada is blessed with a splendid store of minerals. Its mineral industry is now facing an exceptionally rosy future. What of the mineral industry of Nova Scotia? GEOLOGICAL RESEARCH ALLOWED TO LAG RN NOVA SCONA Many years ago, when geological science was in? its infancy, much geological study was carried on in Nova Scotia. In 1827, Francis Alger began work on the iron ores in the Bay of Fundy region. In 1886, E. R. Faribault began his series of remarkable papers on Nova Scotia geology. Between these dates, many others published papers on the geology of the Province. The most outstanding of this early group of geologists was Sir William Dawson, whose published works on Nova Scotian geology extended over the period from 1845 to 1891.

Jan 1, 1937

By V. G. Papangelakis, J. E. Dutrizac, G. Azimi

A new model capable of predicting the solubility of calcium sulphate solid phases in zinc sulphate processing solutions from 25 to 95°C was developed. The model uses the Mixed Solvent Electrolyte (MSE) model of the OLI systems software to calculate the mean activity coefficients of the electrolyte species. The model was tested using recently developed experimental measurements. It was shown to predict accurately the solubility behaviour of calcium sulphate in multi-component zinc processing solutions containing ZnSO4, H2SO4, MgSO4, MnSO4, Fe2(SO4)3, Na2SO4 and (NH4)2SO4. The model can also explain the complex effect of coexisting metal sulphates on the solubility of the CaSO4 phases. The model is a practical tool for assessing the process chemistry of a wide variety of complex aqueous processing streams.

Jan 1, 2008

By Iain G. Bruce

The need to improve supply reliability while improving our environmental record during the past half decade of low metal prices has required the mining industry to prioritise expenditures. Quantitative Risk Assessments using third party reviewers and specialist risk management teams have assisted in identifying hazards that can both disrupt supply and impact the receiving environment. Graphical displays using risk ellipses can simplify the presentation of the results in a Probability-Consequence (PC) graph. Development of risk acceptability envelopes using readily available financial data superimposed onto the same PC space assists management to prioritise their risks and focus on risk reduction measures. Development of this system and examples of the successful implementation of the system from several recent projects are described.

May 1, 2003

By James Ball

The paper describes a new type of pump and related apparatus specifically designed to dredge sea-floor minerals from very great depths. The principle of operation of the dredging system is explained, and the factors which determine the equipment size and the power required for varying mining rates and depths of water are discussed. An estimate of the capital and operating cost of a commercial-scale mining system is presented.

Jan 1, 1968

By G. Swan

"The selection of material comprising a backfill is, of economic necessity, site dependent. Nevertheless, given the existing range of typical components-coarse waste, alluvial sand, tailings a balanced or optimal choice is no straightforward matter. A new design approach toward deciding what constitutes an optimum combination of backfill material promises to be useful. In particular a 'binder ' number, based on the mean distance between aggregate particles, specific surface and cement content, is proposed. Using this number, related empirically to compressive strength, the expected mechanical performance of any cemented fill can be predicted.IntroductionOver the years a considerable volume of information has accumulated on mine backfill material design. The principal aggregate component has been deslimed mill tailings, though more recently admixtures of rock waste, sand and tailings are quite common. For these materials uniaxial compressive strength and percolation rate properties are known to be controlled by, among other things, aggregate grading. While empirical formulae exist for relating grading to percolation rates, considerable uncertainty exists concerning strength development."

Jan 1, 1985

By S. N. Aliferova, E. I. Afonina, S. N. Titkov, A. Ju. Bondareva, N. N. Panteleeva

"Potash ore is mainly processed using the method of cationic flotation. Potash ore deposits of the CIS, namely: at Upper Kama river, Gremyachinsk (Russia), Starobin (Belarus), Tubegatan (Uzbekistan) are characterized by relatively low KCl impregnation (1.0 – 1.5 mm) and contain up to 10% of waterinsoluble impurities (WII). Water-insoluble impurities are presented by aluminosilicate, silicate, carbonate (calcite, dolomite) minerals and anhydrite. In the process of milling the ore to a flotation size there are released and dispersed the insolubles impurities actively sorbing the cationic collector, i.e. aliphatic amines C16 – C22. In this regard there is carried out a preliminary desliming of the ore.Currently grinding the ore to a flotation size (1.5 mm or less) is carried out in rod mills along with forming of a large number of fine-grained ore fractions having the size under 0.25 mm, which results in the increased KCl losses with halite slime waste and reduction in the quality of finished product. There has been developed the technique for processing of potash ores with a high content of water-insoluble impurities (10 – 12%) containing, in different ratios, silicates, carbonates and anhydrite. The technology involves the use of the ore dry grinding to the flotation size and subsequent reagent activation of the processes for sludge removal and sylvite flotation.INTRODUCTIONCurrently there are being developed the potash ore deposits in the CIS countries, namely: at Upper Kama river and Gremyachinsk deposits (Russian Federation), Starobin deposit (Republic of Belarus) and Tubegatan deposit (Uzbekistan). Potash ores are a mixture of sylvite and halite and contain water-insoluble impurities of silicates, carbonates and anhydrite. The content of water-insoluble impurities (WII) reaches up to 10%, disseminated (impregnated) sylvite does not exceed 1.5 mm and in connection with that the ore is crushed to a particle size under 1.5 mm. Ore grinding is performed by wet process in rod mills with producing a significant amount of fine-grained mineral fractions and sludge, which are actively sorbing a cationic collector, i. e. primary aliphatic amines C16 - C22. The ground ore is deslimed and the slime product is directed to a sludge depot (pits)."

Jan 1, 2016

By L. B. Kilius

The composite cathode system based on Ce0.9Gdo.1O2_,5 electrolyte with a painted cathode was used for an intermediate temperature (500-700°C) solid oxide fuel cell. This cathode system was chosen due to its excellent thermal expansion match to the electrolyte, its relatively high conductivity (115 S cm-1 at 700°C), and its low activation energy for oxygen reduction (99 kJ/mol). It was found that the decrease of sintering temperature of the composite cathode system produces a significant decrease in charge transfer resistances to a level of 0.25 SI cm2. The conductivity measurements of porous samples produced values between 40 and 88 S/cm for porosities of 30-40%.

Jan 1, 2005

By M. Leroux, J. A. Finch

"Sizing below 38 µm (400 mesh) is an increasing requirement in mill testing laboratories. The Cyclosizer is gaining wide acceptance in this role. A recent alternative is to use electro-formed sieves (micro-sieves), which are available with openings down to 5 µm. The advantage of micro-sieving is a cut size which is independent of mineral density, easier retention of the fi nest fraction and reduced purchase cost. A simple method of microsieving using an ultrasonic bath, which performs readily to 10 µm, is described.A systematic study of Cyclosizing and micro-sieving is reported for three samples; silica, copper oxide and a lead concentrate. Micro-sieving gave comparable results. Comparison with a standard sizing method, the Sedigraph 5000D, revealed misplaced material in each fraction by both methods. The range for micro-sieving was from 20% to 60% depending on the sieve and material; for the Cyclosizer it was a consistent 40-50% for all cones and all materials. The Cyclosizer can be sensitive to feed mass and particle size for dense materials. It is recommended that for minerals of specific gravity greater than 5, no more than 35 g of -38 µm be used.The disadvantage of micro-sieving is that it requires continuous operator attention and sieving time depends on sample mass. To fractionate 35 g-as used on the Cyclosizer and considered at reasonable mass for mill testing purposes-through 25-, 15- and 10-µm sieves requires about 80 minutes.IntroductionParticle size has a pronounced influence on mineral separation processes. Consequently, the measurement of particle size plays an important part in mill testing. By far the most common method is by screening. This, however, is usually limited to 38 µm (400 mesh) or occasionally 25 µm (500 mesh). Increasingly, mineral products are becoming finer than this limit and consequently finer sizing methods are required."

Jan 1, 1982

By G. Chi

Outline 1.Regional geologic setting 2.Host rocks and structures 3.Mineralization, alteration and paragenesis 4.Geochronology 5.Major and trace elements 6.Fluid inclusions 7.Carbon and oxygen isotopes 8.Conclusions

Apr 1, 2005