Search Documents

By G. Viramontes-Gamboa, A. Encinas-Oropesa, S. Velázquez-Roque, L. A. Ibarra-Bracamontes

Some industrially relevant applications for pyrite nano/micro-particles have been proposed in the literature, such as the catalysis of chalcopyrite leaching, the removal of As(III), As(V) and Cr(VI) from solution, as photovoltaic devices, and others. Even though pyrite can be recovered from solution by flotation, for some applications it may be beneficial to provide pyrite with magnetic properties. In this work, a methodology to synthesize magnetic shell/core composites made of pyrite as the shell and either natural or synthetic magnetite as the core is presented. The size of the magnetic composite may range from tenths to hundreds of microns. The synthesis is basically made by stoichiometrically mixing iron nano/micro-particles with sulfur microparticles with magnetite particles, and bringing the mixture in an oxygen free atmosphere from 200 to 300 °C for 4 h. The composites were characterized by optical microscopy, Scanning Electron Microscopy and X-Ray diffraction.

Jan 1, 2014

By Leroy C. Stewart

Owing mainly to the use of ethylene dibromide in the production of tetraethyl lead for gasoline treatment, there has been a tremendous increase during the past decade in the demand for bromine. In the United States, production, derived mainly as a by-product from the treatment of brines from salt wells, rose steadily from about two million pounds in 1924 to nine million pounds in 1931. In 1936, production amounted to between 20 and 21 million pounds. Much of the increase during the past four or five years has been due to the operation of the Ethyl-Dow Chemical Company's plant, which extracts bromine directly from sea water. The process employed by the Ethyl-Dow Company is somewhat similar to that in use on salt-well brines at their plant at Midland, Michigan, but whereas these brines contain around 1,300 parts per million bromine, sea water contains only 65 to 70 p.p.m.-about as much as the waste effluent in the brine process. By intensive research, however, a process was developed whereby a very considerable percentage of the bromine content of sea water could be recovered, and at a satisfactory operating cost. In its essentials, the process consists in liberating the bromine from the sea water by treat-ment with chlorine, blowing the bromine out of the water by a current of air, and finally absorbing it in a solution of soda-ash.

Jan 1, 1938

By P. M. Shibley

"IntroductionMine drainage, surface. drainage and process liquors are the principal mine and mill effluents. The quantity and quality of these flows varies according to mineralogy, type and scale of mining, the process, tailing disposal, local ground conditions and climate.Typical contaminants remaining after solids sedimentation are colloidal or semi-colloidal particles, acids, alkalis, metals in solution, cyanides and thiosalts. Environmental regulations and guidelines have been issued in detail by the appropriate government agencies and will not be reviewed here. Revisions and additions are being made as our comprehension and abilities increase. Some contaminants of consequence have not been specifically regulated as practical treatment technology has not been identified. Thiosalts fall into that category as do the derivatives of the first stage of cyanide oxidation - cyanates.Most mining activities have present or foreseeable water treatment requirements. Because process economics can be adversely skewed by the environmental factor, the acknowledged objective of every operation must be to identify and anticipate those requirements.The evaluation and selection of water treatment techniques for mine-mill applications is complicated by the fact that most mine-mill effluents are high volume, dilute and chemically complex systems. Treatment processes applicable to most contaminants are: chemical or biological oxidation; neutralization and/or precipitation; liquid/solids separation. Other processes such as ion exchange, electro-deposition, foam fractionation, freeze crystallization and reverse osmosis offer the possibility of selective removal or concentration of contaminents. The latter tediniques, representing a slightly higher level of technology, are less suited to the large, low value flows usually encountered in the mine environment."

Jan 1, 1989

By H. C. M. Gordon

IN every co al mine the hazard of fire in the underground workings is always present. This is a natural condition, because the mineral wrought and the supports normally used are themselves combustible and because underground fires may originate in many ways. The main causes of such fires are: (1) Open lights igniting gas, wood, or the coal itself. (2) Explosives igniting gas or coal. (3) Spontaneous combustion. (4) Electric sparks or short circuits igniting gas, wood, or coal. (5) Frictional heat igniting wood, coal, or oily material. (6) Explosions of gas or coal dust igniting wood or coal. The relative importance of these causes, and others less frequently met with, varies from district to district and depends to a great extent on the equipment and supplies used, on the training and discipline maintained among the workmen, and on the liability of the coal to heat spontaneously. It follows, therefore, that open lights should not be used and that, wherever there is the least possibility of methane being encountered, only locked safety lamps of an approved type should be allowed underground. It follows, also, that only 'permitted' explosives should be used and that the it use should be confined to conditions under which they are ?permitted?. Similarly, electric equipment should be of an approved type and all such stationary equipment should be housed in well-ventilated fireproof rooms. Such rooms, as well as entries to stables and oil houses, should be provided with doors which can be easily and tightly closed and which should be constructed of fireproof material.

Jan 1, 1937

By Boris Yacksic, R. W. Bruce

"The flotation of a cassiterite ore with oleic acid will recover primary or rougher concentrates assaying over 10 per cent Sn, with a recovery of 80 to 90 per cent. These rougher concentrates cannot be up-graded to a marketable grade by normal reflotation. Experiments were conducted on low-grade tin ores, and a process was developed for up-grading the rougher flotation concentrates by a reverse flotation technique. The process was tested on a number of samples of ore from the Catavi mine in Bolivia. The results of these tests showed that a concentrate assaying 40 to 60 per cent Sn could be readily produced, with a recovery of 60 to 75 per cent of the tin in the ore."

Jan 1, 1967

By E. Mataradze

Statistics shows that the majority of accidents with fatal outcome are caused by methane and/or coal dust explosion. This leads to assume that contemporary counter-explosion systems of various designs cannot be considered effective. Considering the growing threat of methane explosion in the coming years along with the development of deeper levels, the improvement of a system for protecting people in underground opening appears urgent. This paper presents the results of the testing of the Automatic System from Methane Explosion in Coal Mines. The protective system consists of: i) a wireless device for the detection of explosions and activation of a protective system, and ii) an absorber with a pyrotechnic device ensuring the discharge of dispersed water. The protective system, at the command of the initiation signal, produces tailored dispersing water mist with droplet sizes in the range of 25?400 ?m along selected tunnel sections.

Aug 1, 2013

By Stephen Hardcastle

Personnel Heat Exposure Issues In Canada?s Deep Mechanized Mines ?Project developed in 2004 ?Base/precious metal industry identified heat stress/management as a major challenge affecting productivity and operating costs ?Project started in 2005 ?Current research nearing completion ?Guidelines, further data analysis and ?Communicating the Science? will continue into 2011 Managing Heat Exposure Control?. The cost implications ?Controlling the environment ?Ventilation already a major expenses/energy user ?Large Canadian mines are currently delivering massive volumes of air 15-20 tons of air/ton ore ?Large investments in ventilation upgrades, mechanical cooling

May 1, 2010

By M. T. Shehata, R. W. Revie, M. Elboujdaini

Environmentally assisted cracks in linepipe steels are initiated either as a result of stresses in combination with environmental effects, as in stress corrosion cracking (SCC), or as a result of trapped hydrogen in the steel, as in hydrogen-induced cracking (HIC). To understand better the mechanism of the crack initiation process, key metallurgical and environmental elements that can affect the cracking phenomena were investigated and are reviewed in this paper. The complexity of both cracking phenomena results from the dependence of SCC and HIC on multiple metallurgical, mechanical, and environmental parameters that may all influence both crack initiation and propagation; e.g., composition, microstructure and non-metallic inclusions in the steel, applied stress, water chemistry in the field, and ionic concentrations in the groundwater near the pipe surface to name a few for SCC. In addition, for HIC phenomena, one can add the concentration of H2S in the fluids transported in the pipe as well as concentration of CO2, pH, etc. In this paper, cracking of linepipe steels is analyzed critically, with particular attention to the crack initiation process. The paper is divided into two parts: The first part covers SCC and the second covers HIC.

Jan 1, 2005

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 R. R. Rogers

ABSTRACT The experiments described demonstrate that crude commercial lithium containing in the order of 0.5 per cent sodium can be refined, the resulting metal containing as low as 0.001 per cent sodium. During the process, the metal is vaporized and condensed at a gauge pressure of less than 0.04 micron. Considerable operating data and a detailed description of the experimental equipment are included. INTRODUCTION DUE TO THE unusual properties of lithium metal, its use is likely to increase considerably during the next few years (1, 2). This is of particular interest to Canadians because there are important deposits of lithium-containing minerals, especially spodumene, in Canada and it is hoped that lithium compounds and lithium metal will be produced from these deposits in the fairly near future. In order to assist in the development of this industry, the Mines Branch of the Department of Mines and Technical Surveys has initiated a programme of research in lithium metallurgy. In 1948, a paper (4) was published on methods of producing lithium metal and its alloys. Data on the corrosion resistance of some lithium alloys were included. In 1949, a paper (3) was published which showed that the addition of a small percentage of lithium to zinc anodes used for cathodic protection will improve their usefulness under certain circumstances.

Jan 1, 1951

By N. Sauret-Szczepanski, G. Patry, S. Gauthier, G. Potvin, C. Munger

Adsorption/thermal desorption with sorbent cartridges and analytical method using gas chromatography coupled to mass spectrometry (GC/MS) was developed for the determination of tetrafluoromethane (CF4) and hexafluoroethane (C2F6) emitted from primary aluminum smelters. A customized cartridge was built like a packed column with a stainless steel tube filled with a specific resin. The optimization of adsorption and desorption parameters was carried out to support the PFC sampling for all aluminum production technologies. The proposed method showed good linearity for concentrations ranging from 10 to 500 ppbv for CF4 and from 5 to 500 ppbv for C2F6 with correlation coefficients above 0.999. In certain conditions, the detection limits of the analytical method reached 0.3 ppbv for CF4 and 0.15 ppbv for C2F6- Using this methodology, a field campaign was carried out using a sequential sampler allowing the simultaneous sampling of PFC with cartridges and sampling bags. The results showed no significant difference (t-test) between the two sampling technologies and no breakthrough was observed from the cartridges .

Jan 1, 2006

By S. J. Cook

Outstanding advances among the metals, marked the mineral production records for Canada during the first half of 1925. Production of metals and non-metals reached a total value of $90,347,698. as compared with $84,307,385. in the first half of 1924, an increase of 7.16 per cent. Metals and non-metals produced during the calendar year 1924 were valued at $17 4,202,537.; production during the first half of 1925 showed a sum equal to 51.86 per cent of this total. Advances among the metals were general. Gold rose to a new record. Lead advanced 62.41 per cent over the high mark attained in the first half of 1924. Nickel production was well maintained. Copper was up a million pounds. Silver showed increased values. Zinc followed the trend in lead to almost double the output recorded in the first half of 1924. Cobalt production continued to improve. Despite the loss due to the protracted strike in the Nova Scotia coal mines which reduced the output of coal in that province; during the six months ending June, to less than half the tonnage reported in the first six months of 1924, improved conditions throughout the rest of the non-metal mining field resulted in the production of non-metals during the half-year reaching a total value of $31,199,233. as compared with $36,844,286. in the first half of 1924; the loss in the value of coal output al one amounted to $5,723,873, while the decrease in the aggregate value of non-metals amounted to only $5,645,053.

Jan 1, 1925

By Andrzej Luszczkiewicz, Magdalena Duchnowska, KGHM Polska Miedz S. A., Witold Pawlos, Jan Drzymala, Alicja Bakalarz, Przemyslaw B. Kowalczuk

Numerous data in the literature confirm that the chemical composition and consumption of grinding media influence electrochemical properties of flotation suspension as well as effectiveness and selectivity of upgrading processes. During a milling process, attrition of grinding media is observed. Depending on the susceptibility to abrasion, the grinding media influence, to a different extent, the redox potential, pH as well as flotation efficiency. As a result, different upgradeability of sulfide minerals is observed. The paper presents laboratory scale flotation results, obtained for the copper sulfide ore from Polkowice Region of KGHM Polska Miedz S.A. in Poland ground in the presence of forged steel, highchrome iron and stainless steel as the grinding media. The investigated flotation feed contained 36 g/t (ppm) of silver and 1.86 % of copper. Several flotation tests were conducted using fixed amount of frother and a mixture of sodium ethyl and isobutyl xanthates as the collector at three different doses of 75, 100 and 125 g/t. A comparison of the obtained results confirmed that the application of grinding media with different chemical compositions influenced the electrochemical properties of the suspension and recovery of silver and copper in the final concentrate. The highest values of redox potential were observed for the stainless steel as the grinding medium. Moreover, in the presence of this type of grinding media, regardless of the collector dosage, the best silver upgrading was observed. For the forged and high-chrome iron media, the recovery of silver depended on the collector dosage. It is indicated that higher levels of the redox potential, together with smaller amount of iron released from the grinding medium, improve the flotation of the silver-bearing mineral compounds from the copper sulfide ore.

Jan 1, 2016

By P. Simon, G. Falkinger, G. Angerer, B. Gerold

"This contribution presents an investigation of the evolution of shrinkage pores during hot rolling with a special focus on the microscopic mechanism. The reliable closure of pores, which inevitably occur during the casting process, is of crucial technological importance for high-quality hot rolled plate products. Therefore, lab-scale tests were carried out under different typical thermomechanical loadings. Extensive data from optical microscopy was collected before and after deformation. The analysis shows that the average volume of pores evolves similar to the volume of an idealized arrangement of voids in an ideally plastic matrix. The average shape of the shrinkage pores, however, was found to be almost constant during deformation. Even though individual pores exhibit complex morphologies far from any idealized geometries, the overall evolution of a large number of pores is well captured by simple assumptions. In addition to the quantitative analysis, a schematic representation of this counter-intuitive behavior is provided. A simple ‘Gurson’-type void evolution equation was implemented in a three-dimensional Finite-Element model of the industrial hot rolling process. With the help of this mechanism-based process simulation the thermomechanical closure of shrinkage pores during the rolling process has been optimized for a variety of plate products.INTRODUCTION Aluminum alloys of the 7xxx series are widely used in the aircraft industry. They have to meet high quality standards regarding microstructure as well as mechanical properties. For hot-rolled aircraft plates, one of the most important quality requirements is that they are free from pores. Pores, however, are inevitably created during the casting process either due to shrinkage or due to the dissolution of gas from the melt. The pores have to be closed mechanically during the hot-rolling process. Therefore, the mechanism of so-called pore closure or void closure has a high technological relevance for the production of aircraft plates. The behaviour of voids in a ductile matrix subjected to mechanical deformation has been extensively studied, especially in the context of damage mechanics. A recent review (Besson et al., 2010) on modeling methods for ductile damage gives a good impression on how much experimental as well as theoretical effort has been dedicated to the problem of void evolution under mechanical loadings. Although void closure has been studied to a far lesser degree, it obeys to the same general theoretical evolution laws as void growth. The most basic theoretical result is that hydrostatic pressure drives void closure, while hydrostatic tension leads to void growth. The mechanism of void closure depends on the void shape. This is illustrated by the example of a flat penny-shaped void, which under compression obviously closes much faster than a sphere with the same volume. Theoretical models have been developed for the evolution of simplified void geometries, such as spheres or cylinders (e.g. Gurson, 1977), spheroidal (Gologanu et al., 1997) and ellipsoidal voids (Ponte-Castaneda, 1994). In industrial cast ingots, however, the pores exhibit very complex morphologies, which are far from any idealized geometry. X-ray tomography revealed ‘tortuous’ voids in a 5xxx aluminium alloy (Chaijaruwanich et al., 2006)."

Jan 1, 2018

By Mike Dry, Mani Manimaran, Mykolas Gladkovas, Mariam Melashvili, Chris Fleming

Development of a new hydrometallurgical flowsheet requires quantitative description and optimisation of all chemical processes in each step in the process, as well as mass and energy balances across a fully integrated circuit incorporating all the unit operations. This paper covers steps leading to early modelling of a gold processing plant based on a bromine/bromide lixiviant. Research conducted at SGS Lakefield in collaboration with Albemarle provided the data that were used in the development of this model. A previous investigation in this series described the leaching behaviour of various mineral types in Stabilized Bromine reagent. This paper is concerned with the gold recovery operations associated with a conceptual bromine leaching process. The recovery of gold by different types of resin and activated carbon was studied, along with various methods of stripping the gold from the extractant. The circuit is closed by electrolysing the spent leach liquor to oxidize some of the contained bromide back to bromine that would allow recycling the regenerated leach solution back to the leach step in the process.

Jan 1, 2015

By Xiaozhu Chen, Qi Ping, Pu Yuan, Qinyong Ma

"In order to investigate the fractal feature of coalmine deep rock fragments under impact loads, variable cross-section split Hopkinson pressure bar apparatus, 50 mm in diameter, was adopted to conduct impact compressive test for rock specimens from -962m deep coalmine. Various impact pressures, such as 0.3, 0.6, 0.9 and 1.2MPa, were selected to implement different loading rates. Sieving statistical analyses were conducted for rock fragments after being impacted, and the particle size distribution of broken rock in various loading rates were calculated with the fractal method and then the corresponding fractal dimension was obtained. Test results shows that there is a good self-similarity and fractal feature in fragments distribution of deep coalmine sandstone under impact loads. The fractal dimension of fragments is between 1.9 and 2.7. The research also indicates that there is an approximate power relationship between dynamic compressive strength and fractal dimension, and a strength power relationship between fractal dimension and average strain rate. Moreover, there is a linear relationship between fractal dimension and specimen absorbed energy. The rock fractured process can be quantitatively described through fractal dimension, which can reflect the deep rock broken degree and is an ideal index to evaluate the distribution of rock fragments.INTRODUCTIONBroken rock is one of the most basic processes in mining operations, rock fragmentation has always been an important index to evaluate rock breaking effect (Xu & Yu, 1984). Macroscopic fragmentation of rock material is the final results of continuous development, expansion, gathering and cutthrough of internal micro-cracks. This process, developing from microscopic damage to macroscopic fragmentation, is an energy dissipation process and shows fractal characteristics (Xie, 1993). Turcotte (1986) has conducted statistical analyses of fragmentation for different kinds of geological materials under various broken conditions, and arrived at the conclusion that fragmentation distribution is a fractal."

Jan 1, 2015

By A. S. Gendron

A brief description of Inco's ORC copper refinery tankhouse and the electrowinning tankhouse is followed by a comparison of the requirements for the production of the high-quality copper in both systems. The description will focus on both tankhouses, with emphasis on experience to date in the electrowinning tankhouse. Particular attention will be paid to sensitivities of each tankhouse to process upsets which can. significantly afject the quality of the product cathodes.

Jan 1, 1977

By A. W. F. Smith, P. B. Prangnell, D. N. Crowther, P. J. Apps

It is well known that the refinement of grain size in metals leads to a significant improvement in important mechanical properties. As part of a European collaborative project, processing schedules have been investigated aimed at producing a homogeneous ultra-fine ferrite and spheroidised carbide aggregate microstructure structure in high carbon (CMn) steels (0.6-1.2wt%C), via conventional 'warm' rolling and innovative Equal Channel Angular Extrusion (ECAE). Suitable deformation schedules were determined from dilatometry and thermo-mechanical Gleeble simulations. Evidence of an ultra-fine ferrite and carbide aggregate microstructure following 'warm' rolling is given. A significant improvement in tensile strength, particularly proof stress (0.2%) was also noted in comparison to material deformed at higher temperatures. Concurrent Equal Channel Angular Extrusion (ECAE) experiments investigated microstructural evolution with incremental strain. Extensive analysis was carried out using various techniques, including high resolution Electron Back Scattered Diffraction (EBSD). Evidence of ferrite grain refinement was noted in a eutectoid composition steel. A sub-micron ferrite structure was observed following high strains (E-3.33) and the mechanical properties exhibit a marked increase in tensile strength.

Jan 1, 2004

By R. Baker

A novel electrochemical half-cell and corresponding working electrode were designed to evaluate the electro-catalytic activities of catalysts in an environment close to that of an operating proton exchange or polymer electrolyte fuel cell (PEMFC). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were employed using the novel cell to characterize various methanol electro-oxidation parameters that contribute to the overall reaction on a fuel cell anode. The effect of temperature on methanol oxidation kinetics was examined in the potential range of 0.31 to 0.65V (vs. NHE). The data was collected in the temperature range of 20 to 80°C. Based on the experimental analysis and literature data, an equivalent circuit model (ECM) for methanol oxidation was proposed and was used to fit the EIS experimental data. The experimental data and ECM electrochemical data was used to extract electrochemical kinetic parameters for methanol oxidation such as the exchange current density, Tafel slope, and energy of activation for the reaction. Kinetic data, especially at different temperatures, is very limited in the literature.

Jan 1, 2005

By Michel Lefebvre, André Piché

Every organization performing R&D is faced with the challenge of introducing new technologies to its operations. Difficulties must be overcome if companies are to realize the benefits anticipated from such developments. This paper outlines the difficulties encountered in transferring to operations various technologies developed at the Mining and Exploration Division of the Noranda Technology Centre. The approach used in the selection of a privileged partner for the technology transfer, the criteria motivating the choice and the process followed to establish the partnership are presented.

Jan 1, 1997