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By S. M. Fatemi-Varzaneh

The AZ31 magnesium alloy is considered as a promising alloy in various applications and industries. Furthermore, to design a proper hot working process (rolling, forging and extrusion), the assessment of hot working behaviour of the alloy is necessitated. Accordingly, the hot deformation behaviour of AZ31 alloy was studied through hot compression testing method. The latter was carried out in a wide range of temperature (523 K to 783 K) and strain rates. The obtained true stress-true strain curves and final microstructures were examined and a partial melting was realized at 740 K. It was concluded that the presence of liquid did change the deformation mechanisms thereby affecting the flow behaviour.

Jan 1, 2005

By Luis Ramirez Grados

El presente texto examina los problemas de diseño que se presentan en el sistema de minado subterráneo debido a su interrelación con los variados escenarios geológicos. Para ello, se cita el ejemplo del acarreo de desmonte y mineral de la Estación de Carguío H-2 del Nv. 2430 de la Rampa RNG 92442 @ -15% hacia el echadero de desmonte y la Tolva de Mineral de la Planta Concentradora en superficie Nv. 2765, donde el sistema de acarreo fue modelado usando simulación, la cual fue utilizada para ver la rentabilidad del sistema scooptram-volquete.

Sep 14, 2009

Sherwood?s Minto Project ? High grade copper copper-gold deposit ? Yukon Territory, Canada ? Development underway ? Permitted ? Production by mid mid-2007 ? 40 40-50m lbs Cu plus Au/Ag by by-products ? Parallel exploration program underway ?Discover more high grade resources ?But what kind of deposit is it?

May 1, 2006

Controlled-blasting experiments in small development drifts were conducted at CANMET's Experimental Mine in 1992 and 1993. The objective of these experiments was to develop suitable controlled-blasting techniques for small development headings that are drilled by jackleg with 32-mm-diam holes. The experimentation was also aimed at providing insight into blast-damage mechanisms. Particular attention was given to the physical-mechanical properties of the rock and the rock-mass structural data. The drift faces were approximately 2.4 by 2.4 m (7.9 x 7.9 ft) in size with 36 to 43 holes drilled to a depth of 2.4 m (7.9 ft). Cartridged water gels, emulsions and semigelatin dynamite were used in the cuts and as primers, ANFO was used as the main explosive and decoupled 19-mm (0.75 in.) diam semigelatin dynamite charges were used in the perimeter holes. Smooth-blasting techniques and presplitting were tested in the underground mine. All of the blasts were monitored with a multichannel blast-vibration monitor, to which was attached sets of high frequency geophones and accelerometers. These experiments demonstrated the efficiency of controlled-blasting techniques for the reduction of blast damage and also demonstrated the need to improve the safety and efficiency of using explosives.

Jan 1, 1997

By S. Roath, F. Paul, D. Melville

Several attempts have been made over the past 40 years to separate red blood cells from whole blood using a magnet. This has been achieved by the authors by using a high gradient magnetic field and " carrying " the red cells in a suitable reducing agent - the deoxyhaemoglobin so produced has 4 unpaired electrons per atom giving appreciable paramagnetic moment as opposed to the usual oxygenated form which is diamagnetic. Red blood cells so separated appear to be undamaged and can be reinjected into a donor animal where their survival is shown to be normal using an isotope tagging technique. Studies on function of the white blood cells and blood platelets also indicate that they are functionally unchanged by separation process.

Jan 1, 1980

By K. F. Unrug

Martin County Coal Corp. is located in Martin County, KY, in the Appalachian coal fields, near the West Virginia border. The company's total leasehold covers more then 133.5 km' (33,000 acres). Total annual production at Martin County Coal Corp. is currently 2.2 Mt (2.5 million st). In certain years, though, it exceeded 2.7 Mt (3 million st). About 45% of the annual production comes from two surface mines. The balance is produced from five underground mines. Martin County Coal's work schedule consists of two nine-hour shifts a day, 240 days a year. Topography The topography of the area is characterized by rugged hills and ridges and sharp V-shaped valleys demonstrating a cliff and slope topography. This topography consists of alternating benches of outcrop sandstone and slopes. The deep valleys have been carved out by many small streams in the area. These streams are contained within the steep slopes of narrow, twisted mountain ridges. The ridges are underlain by massive sandstones that, being resistant to erosion, create sharp, rocky morphology. The height of the hills above the valley floors ranges from 122 to 244 m (400 to 800 ft).

Jan 1, 1991

By G. Merazchiev

In the selection of copper ? molybdenum concentrates with the use of reagents containing sulfide ion ? sodium sulfide, sodium hydrosulfide etc for depression of copper minerals and pyrites, big part of depressor is oxidized by oxygen, which is dissolving in pulp during aeration with air in flotation machines and it is expended unproductively. This is the main reason for the big expenditures of depressor, reaching up 15~20 kg/t collective concentrate and the high exploitation expenditures for the copper ? molybdenum selection. Effective direction for lowering expenditure of depressor and increasing of the technical ? economical effectiveness of moly production is the conducting of the selection in nitrogen medium. In the paper are shown the results, obtained by applying of this direction in selection of collective copper ? molybdenum concentrate from the porphyry copper deposit ?Ellatzite? ? Bulgaria, in which the ratio Mo:Cu is over 1:120. In laboratory conditions, through comparative experiments in medium of air and nitrogen are defined: expenditure and initial concentration of NaHS in pulp for effective depression of copper minerals and pyrites; kinetics of flotation process of molybdenite; influence of pulp density; emf (negative milivolts) of pulp and the expenditure of nitrogen on tech-nological indexes of molybdenum flotation. When working in nitrogen medium decrease of NaHS in rougher molybdenum flotation from 40% to 45% is settled. When nitrogen is also fed in cleaner stages, the total expenditure of depressor is lowered by 64%. The quality of end molybdenum con-centrate is raised with over 5%. On the ground of the results of laboratory studies and of world practice data, an industrial installation for selection of copper ? molybdenum concentrate in nitrogen medium in Wemco inert ? gas machines.

Jan 1, 2014

By Fernand Dubuc

"The New Pascalis property is situated in Louvicourt and Pascalis townships, about 200 km east of Val d'Or, Quebec. It is made up of 38 claims under option to SOQUEM since August I, 1981 during which time SOQUEM has earned a 60% interest. The property is underlain by archean basaltic volcanics that have been intruded along the west boundary by the Bourlamaque batholith, and by north -trending dykes.The 1982 disco very is related to the re-evaluation of a 1931-gold showing located in the southeastern part of the property, a combination of the presence of a weak IP anomaly at the eastern end of the showing and overburden stripping at that location, resulted in the discovery of a mineralized diorite dyke.The dyke, which strikes N 20 ° Wand dips vertically , has intruded E-W striking agglomerates. The dyke contains south dipping, gold-hearing quart z-tourmaline-pyrite veins that are distributed in a ladder-type arrangement. Visible gold may he observed in drill core, and is generally associated with pyrite porphyroblasts.Diamond drilling has outlined th e dyke for a strike length of 300 11/ and a width of about 10 m, Result s of this drilling indicate, to a depth of 155 m, reserves of 834 000 metric tonnes grading 8.25 g Au/t un cut or 5.38 g Au/t cut to on e ounce. However, four deeper holes have added depth extension to 400m. Also, west of the dyke and within 150 m, other promising gold values have been intersected within quartz-tourmaline veins associated with other parallel dykes."

Jan 1, 1985

NOTICES The Institution of Mining and Metallurgy The Institution is to hold a one day meeting entitled "Sampling in the mineral and metallurgical processing industries" at Imperial College, London, on 2nd July, 1973. International Conference on Air Pollution This Conference is organised by the Department of Health and the National Association for clean air. Consas 74 The Fifth Conference of Southern African Surveyorswill be held in Salisbury, Rhodesia, from 3rd to 9th February, 1974.

By Ronald C. Bethard, Kenneth W. Ely

The liberation of methane during underground coal mining causes serious safety concerns. During a mining cycle, with mechanized mining equipment, thousands of cubic feet of methane are released from coal seams, discharged to return air courses, and vented to the atmosphere through mine fans. This has been the traditional way of removing the explosive hazards of methane gas from the mine. Through horizontal and vertical degasification techniques, this hazard can often be handled in an equally safe and much more profitable manner. Basically, degasification allows for the controlled reduction of inseam methane content of coal prior to its mining. It is the responsibility of mine management to evaluate these degasification programs and ensure that the program itself does not introduce some new risk to the mining process. The removal of methane gas from underground coal mines using horizontal and vertical degasification is a relatively new concept. Products and systems used in degasification continue to evolve. Site conditions vary also, so no one system or equipment can be said to be the safe answer for degasification in all situations. A constant process of cooperation and evaluation by mining and degasification management should result in a safer and more profitable mine.

Jan 1, 1989

By V. C. P. Morfopoulos, N. Arbiter

Theoretical and experimental studies of the interactions of mineral particles with electrical fields of cylindrical symmetry have been made. Theoretically, an expression relating field gradient and intensity to the force experienced by a dielectric particle was derived in a manner paralleling the magnetic analog. Pauthenier's and Cohen's expressions were considered in the evaluation of coulombic forces. Comparison of dielectric and coulombic interactions of minerals exhibiting a wide difference in dielectric susceptibility revealed the potential significance of dielectric forces in a field of appropriate characteristics. Experimentally, apparatus was designed for the study of forces experienced by a single stationary particle in an electrostatic field. This permitted the separate and precise measurement of dielectric interactions in the field. The experimental results were in good agreement with the theory and with relevant published data. Dielectric forces were found of comparable magnitude with coulombic in the presence of an adequate field gradient. Prolonged exposure of minerals to an inhomogeneous field was found to enhance the dielectric response. Dielectric inter- actions properly employed may thus be important in electrostatic concentration techniques. Conventional electrostatic separation techniques employ forces between charged particles and field electrodes to establish the trajectories which effect separation. Uncharged mineral aggregates, although unaffected by homogeneous electrical fields, should respond to fields exhibiting appropriate orientation and electrical gradients. The purpose of this paper is to establish the theoretical and experimental base for the comparison of the forces due to dielectric-field interactions with those of electrostatic origin. Apparatus and techniques developed for the determination of dielectric interactions are described and data on the dielectric forces experienced by stationary particles in cylindrical fields are reported. Finally, a quantitative comparison of dielectric and electrostatic forces is given. THEORY Dielectric Forces: When dielectric particles, minerals for example, are placed in an inhomogeneous field they experience interactions that give rise to substantial dielectric forces.' The latter were shown proportional to the intensity of the field, the potential gradient, the size of the particles and the dielectric permittivity difference between the particles and the medium. The properties of the inhomogeneous field, E, and the magnitude of the gradient, dE/dl, depend on the geometry of the system in question.

Jan 1, 1965

Seven papers included in Session 8 of the Third International Mine Water Congress under the heading "Achievements in Mine Water Management & Research" have been reviewed. Only one paper, a case study by Masters on biological treatment of inorganically polluted effluent, has any connection with research in the sense of seeking new, generally applicable knowledge which would advance the frontiers of mine water management. The remainder deal with various aspects of the management of mine water ranging from investigation of the geology of a specific aquifer system through operating dewatering systems to the management of specific effluent disposal problems.

Jan 1, 1988

By S. Dessureault, Z. Gavelan

As globalization continues, sustainability and social responsibility has become essential in foreign mining investment. However this global trend and the increasing acceptability toward the globalization process, viability and sustainability are not always achieved. Viability and sustainability of mineral projects is dependant on the social and political environment of the region where the mining venture is located and is based on the interaction between the mining entrepreneurs, national-local government representatives, communities, grass-roots groups and independent civil organizations. These are the organizations, which play the acting roles on the viability of mining projects and are the main source of socio-political risks for the project. Throughout the decision-making process to invest in a mineral project, socio-political risks are quantified using a set of measurable variables. Nevertheless, these risk measures should be dependent on specific industries. Two mineral projects, even in the same mining district, may have significantly different political risk profiles based on their own socio-political variables. This paper describes a methodology that takes into account local social and political variables in defining a project-specific’s political risk profile. This contrasts with more typical political risk measures that focus on the country’s overall risk profile. Mining operations must operate on a local scale necessitating the development measure that considers more local variables.

Jan 1, 2004

By S. W. Ihle, L. J. Warren

A sample of garnet from the scheelite ore body on King Island, Tasmania, Australia, was upgraded and ground to produce an ultrafine portion suitable for micro-electrophoresis. X-ray and chemical analysis identified the garnet as andradite with some admixed grossular. At neutral pH the garnet particles were negatively charged, their zeta potential becoming rapidly more negative with increasing pH. An iso-electric point was found at pH 3.5. The effects on the zeta-potential of various electrolytes, hydrolyzable metal ions, and flotation collectors were also studied.

Jan 1, 1976

The disadvantages of the present zinc producing methods, RLE and ISP, are high energy consumption and environmental problems. Therefore, efforts have been directed in Outokumpu Zinc towards the development of alternate routes. One interesting pyrometallurgical process to produce zinc is to inject zinc calcine together with a solid reductant into molten iron, saturated with carbon. This process has been studied by thermodynamic calculations, laboratory tests and mini-pilot test runs at Outokumpu Research Oy, Pori, Finland. The results of these tests are presented and discussed in this paper. The mini-pilot tests demonstrated that over 97 per cent evaporation of the zinc was possible using a reactive coal dust as the reducing agent. The recovery of zinc in the metal phase was at best 88 per cent of input zinc, but only part reported in molten lead in the splash condenser. The final metallic zinc contained at best 98 per cent Zn, the main impurities being dissolved lead and coal carried along with the flue dusts.

Jan 1, 1993

By Jim Merza

The recent heightening of environmental issues has forced more and more mining operations to focus on developing new methods to control dust problems encountered at their concentrate dryers, stock piles, tailings ponds and during the loading, transportation and unloading of their products. The development of dust control agents requires a quick reliable and most of all accurate method to evaluate the performance and to optimize the formulation of these products in the laboratory, thus avoiding expensive field trial evaluations. This paper gives an overview of the industry requirements for specialty dust control agents, application techniques and current laboratory evaluation procedures. The paper will also outline the development of a unique dust suppression testing apparatus called the "Dust Box, which is used to evaluate chemical dust suppressants at the laboratory level. Laboratory results from two test programs on different substrates are presented in the paper.

Jan 1, 1994

By W. H. Stahl

The continuous vacuum filtration is the solid-liquid separation process that is nowadays most frequently used in the beneficiation industry all over the world. After a development time of several decades, the various filter types such as drum filter, disk filter, plate filter and belt filter can be consideres as a sound functional design ensuring a trouble-free operation. Nevertheless, the vacuum filtration does no longer meet the present and future technological requirements. The moisture content of filter cakes is too high. Their thermal secondary drying is too expensive (coal, ores) and may bring about undesirable material changes and the filter cake conditioning with water-binding substances for dumping purposes is too costly.

Jan 1, 1983

By Stephen R. Grano, Jon Glatthaar, Philippe Steinier, Christopher J. Greet

"The importance of the oxygen content of sulphide mineral pulps in determining which reactions occur, and their subsequent influence on flotation behaviour is grossly underestimated in most operating concentrators. While pH is routinely monitored, Eh and dissolved oxygen measurements are obtained infrequently. However, dissolved oxygen measurements in conjunction with other pulp chemical parameters (i.e. pH, Eh, and EDTA extractable metal ion analysis), can provide valuable insight into where and what type of reactions are occurring within a circuit. Unfortunately, these readings yield “instantaneous” measurements of the pulp chemical parameters.What is needed is a means of establishing how reactive a pulp is, and how this reactivity changes as components of the system are manipulated. Oxygen demand provides an opportunity to do this. Several attempts at measuring the oxygen demand of a pulp have been made in the past with varying degrees of success. Most notable among these are Noranda and BOC Gases.Learning from these experiences, Magotteaux have developed the MagO2 ® demand vessel to measure the oxygen demand of mineral pulps. This paper described the apparatus, and through a case study on Broken Hill lead/zinc ore demonstrates how the MagO2 ® demand vessel is used.INTRODUCTIONThe role of oxygen in flotation is complex. While a considerable body of work exists demonstrating the strong involvement of oxygen in the interactions between sulphide minerals and collector (Gaudin and Finkelstein, 1965; Gaudin, 1974; Woods, 1984; Laajalehto, Nowak and Suoninen, 1993), the presence of oxygen can also affect the oxidation state of sulphide and non-sulphide minerals, which can impact on their flotation behaviour. Further, sulphide mineral oxidation is related to their oxygen demand (Spira and Rosenblum, 1994)."

Jan 1, 2004

By Joaquin Marti, Peter A. Cundall

This paper reports on some recent work in which several schemes were developed to model jointed rock under high stress, with particular reference to the phenomenon of "block motion" observed during dynamic loading of underground structures. Three approaches were made, corresponding to an increasing relative importance of internal block deformations as compared to rigid block movements. The first one uses distinct element method and assumes internally rigid blocks, which can break, repeatedly, whenever an empirical crack criterion is met. In the second approach each block is allowed three degrees of freedom to deform internally. The third approach, still in the development stage, permits arbitrary deformation of all blocks, which are internally decomposed into finite-difference zones and automatically rezoned during slip to preserve the calculation accuracy on joints. The last two schemes allow arbitrary constitutive relations for the intact rock, and all three schemes permit the geometrical arrangement of joints to be arbitrarily complex, in contrast to normal Lagrange, finite-difference programs, which are unsuited to model discontinua.

Jan 1, 1979

By James E. Hoffmann

This paper reviews the chemistry of selenium and its compounds as it applies to the recovery of selenium from electrolytic copper refinery slimes. Based on this chemistry various processes for the extraction and recovery of selenium from refinery slimes are explained and developed. The optimum selenium technology processes is dependent upon many factors including copper refinery location, environmental and regulatory conditions, local markets for selenium or selenium chemicals, and other plant processes. For this reason there is no one best process but rather a variety of useful processes for winning selenium. Those which have demonstrated consistent utility in both ease of recovery and reliability are discussed in more detail. Recovery of selenium by Doré furnacing of slimes is the topic of a separate paper. The companies that have developed selenium extraction technology are not being cited in this paper for the following reasons: o Their current technology may be different o The actual inventor of a process is difficult to credit since many different organizations have pursued parallel inquiries in developing better processes. Finally, some selenium extraction processes have been omitted; not because they are unworthy of consideration but rather due to limitations of space.

Jan 1, 1984