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By J. A. Finch, G. Labonté

"A long-standing objective has been to obtain interpretable measurements of the oxidation-reduction potential in mineral slurries. For this purpose several sensing electrodes (black platinum wire, platinum foil and spiral, gold foil and spiral, and sulphide minerals such as chalcopyrite and galena) were investigated to determine their response to the presence of sulphide minerals in the pulp, and to the addition of reagents commonly used in flotation. The observed discrepancies between the electrodes may be explained using a combination of the classical mixed potential model for complex solutions and the probability of contact between the mineral particles and the sensing electrode. It is shown from laboratory testwork that gold spirals are preferred over platinum electrodes. Finally, some of the practical aspects of using the electrochemical measurements in a plant environment are discussed.IntroductonThe interpretation of flotation of sulphide minerals in terms of electrochemical (electron transfer) processes has brought new possibilities for process control of selective flotation. Investigations on massive and compacted particulate bed electrodes have shown that the flotation of a given mineral in the presence of a collector can be controlled by the potential induced on the mineral surface. Also, phenomena such as collector less (self-induced) flotation, activation by heavy metal ions, and natural selectivity sustained by galvanic coupling during flotation might also be controlled by electrochemical means.The technique for measuring electrochemical potential in slurries is an adaptation of that used for solutions. The measurement of the oxidation-reduction potential of a solution (ORP , Redox, Eh) is usually carried out by immersing a noble metal electrode (platinum, gold or silver) and a non-polarizable reference electrode: Standard Hydrogen Electrode (SHE), Standard Calomel Electrode (SCE), or silver/silver chloride (Ag/AgCl) in the solution. (The abbreviation Eh implies the SHE is the reference electrode.) The potential difference between the two electrodes is measured using a high impedance electrometer. ASTM standard D 1498-76 (revised 1981)(1) covers the practical details of such measurements; however, it does not deal with their meaning either in complex solutions or in mineral slurries ."

Jan 1, 1988

By Paolo Farina

Slope monitoring radar has emerged in the last ten years as a leading edge tool for monitoring movements in natural and engineered slopes, thanks to its ability to rapidly measure slope movements with millimetric accuracy over wide areas in any weather conditions, obviating the need to install artificial reflectors. In recent years, slope monitoring radar has experienced significant improvements in its performances, mainly thanks to the use of different radar technology, such as Synthetic Aperture Radar (SAR), able to overcome some of the limitations of the first generation of radar and to provide higher spatial resolution, longer working distances and faster acquisition time. One of the leading applications of this technology is today represented by slope monitoring within the surface mining industry. Prominent international mining groups currently employ slope monitoring radar, based either on Real Aperture Radar (RAR) and SAR technology, for active and background monitoring of open-pit walls. The main technical features of typical slope monitoring radar based on SAR technology along with their possible applications are presented in this paper along with recent case studies of successful slope monitoring in open pit mines.

Jun 1, 2012

By D. Chadwick, J. W. Matousek

Between 1860 and 1890 -- from the time of the American Civil War to the last decade of the 19th Century -- nickel production in North America was dominated (even monopolized) by the output of the industrial complex of the Gap Nickel Mine near Lancaster, Pennsylvania and the American Nickel Works in Camden, New Jersey. In some years, from one sixth to one third of the world's metallic nickel supply came from this enterprise. Mining and smelting were conducted at Lancaster; a matte of high iron content was shipped to Camden for pyrometallurgical and hydrometallurgical refining to produce nickel metal, copper sulfate, and cobalt oxide. The high purity nickel product was rolled into sheet for marketing, primarily for coinage, as nickel had few other uses at that time. The undertaking experienced all of the problems that face the mining and metallurgical industries of today: declining reserves, high labor and fuel costs, high transportation costs, fluctuating demand and prices, pollution concerns, and foreign competition. The technical features of the geology; the mining, smelting, and refining operations; and some of the economic aspects are assessed. The view is taken from that of the present time -- seeking those lessons from history that we are supposed to learn or face the prospect of repeating the mistakes of the past.

Jan 1, 2005

By M. H. Moys, C. Bhondayi, Eric Tshibwabwa

"The relationship between froth bubble size as represented by intra-bubble impact distances (IID) and flotation performance is investigated. Experiments using an artificial ore comprising of limestone as the floatable component and silica as the gangue material were carried out in pseudo-steady-state circuit. A method to measure IIDs developed by Bhondayi and Moys (2014) was then used to measure froth bubble sizes as a function of froth height, superficial gas velocity and feed rate (pulp residence time). Samples for flotation performance evaluation were also taken. Results indicate that as froth height increases, the average IID values increase resulting in a decrease in limestone recovery while the grade increases. Increasing gas rate results in lower IID values that are accompanied by high recovery and low limestone grade. The effect of feed rate on both flotation performance and average IID values depended on froth depth and gas rate. Average IIDs largely remained the same at the two feed rates investigated.INTRODUCTIONIt is regarded as obvious that froth bubble size distribution (FBSD) will have an effect on plant grade and recovery. As the average FBSD decreases, the bubble surface area flux will increase making possible an increase in recovery and a decrease in grade. The opposite trend will be involved if average FBSD is increased. However: no method for measuring FBSD has been available, so these trends have not been studied in any detail. Bhondayi and Moys (2014) developed a novel technique to measure or estimate froth bubble sizes. Although they established a potential to use this method in understanding froth performance, no data have been presented to assess the correlation between the estimates of bubble sizes and actual flotation performance. In this work experiments are done to establish how the change in froth phase bubble sizes affect flotation performance. Flotation performance will be evaluated using recovery and grade. How water recovery to the concentrate changes with changes in bubble sizes will also be evaluated. It is known that water recovery is approximately inversely proportional to the square of the overflowing bubbles sizes. It will be interesting to establish how the rate of change of bubble sizes changes with water recovery."

Jan 1, 2016

By W. Mirihange

Considerable mechanical property decline is always observed at the Heat Affected Zone (HAZ) of AA 5083, This occurred as a result of the thermal effect on the hardened material, It is highly beneficial to have a prospective metallurgical procedure to overcome this decline of properties. Therefore, experiments were set to evaluate the effectiveness of a quick post weld heat treatment process with the AA 5083, Optimum results were obtained at 473K and with approximately 600 seconds time, The interplay between the time, temperature and mechanical properties are possible to explain by the Lifshitz-Slyozov-Wagner (LSW) theory and by considering the composition of the material.

Jan 1, 2005

By J. P. Weiler

The increasing use of high-pressure die-cast magnesium alloys in the automobile industry requires a better understanding of the mechanical properties, the microstructure, and particularly, the relationship between these two. The goal of this study is to first understand the microstructural features which control the mechanical properties observed from an AM6OB magnesium alloy, and second, to be able to predict the local mechanical properties based on microstructural features encountered in different areas of the die-cast component. The two main tools used in this study are spherical indentation testing, used on local areas of the die-cast magnesium alloy AM6OB to detect changes in microstructure and mechanical properties, and X-ray tomography, used to non-destructively investigate the internal porosity in a sample. The results from these tests are then used to predict the local mechanical properties such as the yield stress, the strain-hardening characteristics, and the fracture properties of the AM6OB component.

Jan 1, 2006

By Kremena Dedelyanova

The paper presents research of mechanism for the creation of air bubbles in vibratory a column flotation machine. Factors are discussed that influence the increase in the duration of the bubble in the area of contact with the mineral particles. Formulas are derived for the parameter effect of vibrations, applicable to the design of flotation machine. The collision efficiency of the bubbles in a vibratory column flotation machine is determined.

Aug 1, 2013

By K. Johanson, M. Hubert, C. Eckert, D. Ghose

The mining industry routinely processes material with different particle sizes. Coal, nickel ore, copper ore, lignite, shale, and phosphate ore are all examples of materials with wide particle size distributions. It is often assumed that these materials are homogenous and that any particle size distribution has the same chemical activity and composition. It is entirely possible, and quite likely, that chemical composition is a function of particle size distribution. In addition, particle size distributions in ore materials are often responsible for the difference in flow behavior in process equipment. This is evident in coal electrical production facilities. Fine coal may have the same ash content, sulfur content, and BTU value as coarse coal. However, all electrical production facilities know the extreme flow problems that result when attempting to handle wet fine coal. Segregation of these bulk materials is an important issue that must be understood to prevent these cohesive flow problems. Additionally, fertilizers are mixtures of particles with different shape and sizes. These mixtures must remain homogenous to optimize fertilizer performance. Segregation leads to poor product quality. This paper presents a method of measuring the magnitude of sifting segregation occurring in bulk material and the relationship between the strength of the bulk material and the separation tendency. It shows an inverse relationship between the yield strength of the material and the bulk segregation.

Jan 1, 2004

By B. M. Das, D. B. Cross

"In June 1983, the Computer Applications and Process Control Committee (CAPC) of the Canadian Institute of Mining and Metallurgy (CIM) circulated a questionnaire to coal mining, exploration and consulting companies in Canada to determine the industry's level of interest in holding a workshop-style meeting to introduce company personnel to ""state-of-the-art "" computer systems designed to carry out specific technical and management junctions. It was necessary to conduct the survey to determine the specific fields of application and the nature of training which are of most interest.Almost universally, the companies expressed interest in computer workshops and training for applications in the Canadian coal industry. The survey showed that all categories of personnel felt the need for some sort of training. Areas of specific interest identified were: exploration and geology, mine design, reserve calculations, coal mining technology, coal preparation, rock mechanics, ventilation, financial planning, and process simulation. The details of this survey together with an assessment of the significance of computer applications in the Canadian coal industry are presented in this paper."

Jan 1, 1986

By D. C. Martin, P. M. Hawley, C. P. Acott

"In bedded deposits such as coal or sedimentary iron, economic limits of mineable reserves are clearly defined by the footwall of the seams or ore-bearing units. Where open pits are developed in dipping strata, a long, high footwall slope may result. In many cases, unbenched slopes excavated along the base of the lowest mineable seam are operationally simple, economically desirable and geotechnicalty practical, although a variety of failure mechanisms may develop. This paper examines the engineering geology and rock mechanics parameters of importance in the design of footwall slopes. Possible failure mechanisms and stability analysis methods are described. Design considerations for benched and unbenched slopes are discussed with prime consideration given to development of long high stopes without benches or with a minimum number of benches. IntroductionIn bedded deposits, the ultimate depth and economic viability of an open pit in dipping strata may be controlled by the design of the footwall slope. The stability and, hence, design of footwall slopes is strongly influenced by the engineering geology and rock mechanics parameters of the slope forming materials. A clear understanding of the structural geology, engineering geology and tectonic history of the deposit is essential to assess the behaviour of the slope. This is particularly important for long high, unbenched footwall slopes such as shown in Photo I.A rational footwall slope design requires identification and assessment of all possible slope failure mechanisms with respect to the proposed slope geometry. Stability analyses of each potential failure mechanism are used to identify the main controls on slope stability and to develop appropriate slope design criteria. The optimum slope design is based on the most economic and geotechnically practical slope geometry with due consideration of operational constraints and of the possible advantages of specific remedial measures."

Jan 1, 1986

By P. J. Finnis

This paper describes the use of wire rope on open-pit mining equipment, giving specifications and examples of the performance achieved. Installation methods are also discussed, making the paper of considerable practical use to mine operators.

Jan 1, 1973

By D. M. Cruden

"When two discontinuities form a tetrahedral wedge in a rock slope, a factor of safety for the wedge can be simply calculated (if motion is driven only by gravity and resisted only by friction) from plots of the normals to discontinuities on an overlay of a polar, equal-area spherical projection to which the great circles of a similar equatorial projection have been added.IntroductionThe stability of slopes in rock masses is often controlled by the discontinuities that exist in the masses. In particular, the geometry of the discontinuities constrains the ways in which the mass may fail. Displaying the orientation of the discontinuities on a spherical projection has been found to be a useful way of identifying possible failure modes. The most concise display shows the orientation of the normals (or poles) to the discontinuities that compose the fabric of the rock mass. Computer processing of large samples of discontinuity orientations is necessary if the sampling biases identified by Terzaghi (1965) are to be routinely corrected. Fortunately, displays of the poles to discontinuities (or pi diagrams) are relatively easily produced on the line printer of a computer or by a computer plotter (Cruden , 1978; Ramsden and Cruden, 1979). Unfortunately, further analysis of the stability of a rock mass has tended to use traces of typical discontinuities on a spherical projection rather than pi diagrams; examples may be seen in Hoek and Bray's book (1981)."

Jan 1, 1990

By T. Kawai

Japan Oil, Gas and Metals National Corporation (JOGMEC) has started an exploration program for Seafloor Massive Sulfides (SMS) in the EEZ of Japan, and launched an investigation program for mining, processing and environmental impact on SMS development. With regard to the mining aspect, the mining system consists of three units: a mining unit on the sea floor, an ore lift-up unit to surface, and a mining support vessel unit which has an ore unloading system that unloads onto a shuttle ship. Regarding the mining unit, JOGMEC and certain Japanese mining and machinery companies developed two types of state of the art mining testing tools. Excavation tests on the actual SMS site in the Okinawa Trough, south-west of Japan, were conducted in 2012. In these tests, the functions of the testing tools, such as cutting ore, moving on the seafloor and climbing up slopes having steeper than a 25 degree gradient, were confirmed. The physical characteristics of the ore, which are key parameters for establishing a mining system, are yet to be fully understood as the exploration program has been undertaken simultaneously. Hence, those examinations have been carried out by ground cutting experiments, analysis of drilling core data, and the like. This paper describes the outline of a proposed mining system, mining testing tools and results of the on-site mining testing.

Aug 1, 2013

By Rod Maclean, George Stewart

"This paper covers the planning, development, and mining of an underground pillar complex using a bulk mining method. To achieve the long-term goal of continually improving our operating processes, all cut-and-fill and undercut-and-fill workplaces at Thompson Mine have been evaluated for their conversion potential to the bulk method referred to as VerticalBlock Mining (V.B.M.).Since December 1979, conversion has occurred to the extent where 80% of the ore hoisted is mined using Vertical Block Mining (V.B.M.).Productivity and profitability have been substantially improved by converting to this bulk method, especially in pillar areas.IntroductionThompson Mine is a 6000 ton per day underground nickel mine located 3 miles outside the City of Thompson, 400 air miles north of Winnipeg . The mine has two shafts, T-l and T-3 (Fig. 1). The T-l shaft is 4427 feet deep with the deepest mining taking place on 4000 level. The T-3 shaft, which is the area of this presentation, extends to a depth of 2607 ft with the deepest operating level at 2400 ft. The two shafts, some 10 000 ft apart, are connected underground on numerous levels. The ore mined at T-3 is trammed on 2400 level to the T-I main ore pass and hoisted through the T-l shaft. Eight hundred and fifty thousand cubic feet of fresh air per minute ventilates the mine.The 1400 level 310 pillar complex is located in the T-3 mine area. There are six rib pillars, two crown pillars and one main pillar (boundary pillar between cut-and-fill stopes) within the complex (Fig. 2). The majority of the ore in this area has been mined using mechanized cut-and-fill techniques .Undercut-and-fill mining was the method originally planned to recover these pillars. It is slow, labour-intensive, and requires extensive use of timber during the mining cycle. The extraction drifts in the area are heavily timbered due to their proximity to the ore and the age of the facilities. Increasing drift maintenance costs and the successful mining of two main pillars with V.8.M. techniques provided the stimulus to review the mining plans for this area."

Jan 1, 1988

By G. A. Buckland

"The development, in Ontario, of a common industry-wide program for the development of skills for employees in underground hard-rock mining is described. This program is designed to increase the productivity of individual workers by improving their skill levels, while at the same time ensuring that employees are instructed in the requisite safety and health aspects of performing various underground tasks. The program's development through a management-labour-government tripartite approach is described. How this program was coordinated with new Government Regulations on Occupational Health and Safety dealing with mandatory training of underground employees is also outlined. IntroductionThis paper will describe briefly what modular training is all about and outline why, and how, it was developed in Ontario on an industry-wide basis. Simply stated, what's been accomplished to date is an industry-wide program for developing the mining skills of underground production employees.The basic objective of this program is to improve the productivity of underground workers. It involves developing an employee's skills to improve his productivity and, because working productively involves knowing how to do a job safely, the program includes instructing an employee in the various safety and health aspects of underground work. An important and, I believe, distinguishing point about the development of this program is that it has been done with the full participation, cooperation and commitment of management, labour and government.It's of considerable interest to note that companies in Ontario who are now using this program are finding that new employees are approximately six months further advanced in productivity than was the case before its use, and in some cases the frequency of accidents has shown a reduction among those employees who have taken this program as compared to those who haven't"

Jan 1, 1980

By R. Kamguem

The surface of a mechanical part plays an important role in determining performance in service. The presence of scratches left by the cutting or tearing of the material on the surface of the workpiece supports the concentration of stress and strain. This article presents the experimental study for high speed milling of the aluminum alloy 7075-T6, using cutting tools different by the nose radius and coatings (TiCN, TiAIN, TiCN + A12O3 + TiN). A multi levels factorial design of experiment (DOE) and statistical analysis was used. The roughness parameters investigated are Ra, Ra, Rv, Rc, Rsm, and Rk. The results show that the feed rate, the types of coatings and the geometry of the cutting tools have the most significant impact on the surface roughness profil. Surface finish charts according to feeds and cutting speeds were established for each tool tested.

Jan 1, 2011

By P. L. Wright

"This is a brief history of the development of the mining project, with a description of the proven geology. The paper describes how the experiences gained progressively demanded change in the mine design. The equipment used is described, together with methods of working. Interesting facts have been proved regarding gas emissions and roof. supi;iort. The. working cycles evolved are completely flexible m operation and lend themselves to maximum utilization of the most productive units. The two underground mines are compared, showing the variance in conditions already experienced. Programs currently in operation to improve standards and production are: the training of miners, maintenance men and officials; experiments in floor consolidation and continuing roof support trials; and the effect of comparative stability of working crews on the performance of the operation."

Jan 1, 1973

By M. Duncan

Lightweight, high-pressure cylinders for compressed hydrogen storage are essential components for fuel cell vehicles. Storage volume and mass are two key considerations. Current on-board hydrogen storage systems are based on a maximum pressure of 350 bar. While 350 bar systems are excellent solutions for many applications, some situations require higher storage densities due to space restrictions. As a result, significant research and development work has been expended by cylinder manufacturers, systems providers, testing agencies and automotive manufacturers to develop 700 bar systems with reduced storage volumes. Dynetek Industries Ltd. has proactively developed several 700 bar storage cylinders based on a seamless aluminum liner over wrapped with a carbon fiber composite. This paper presents the challenges and processes involved in the design, testing and certification for Dynetek Industries Ltd. 700 bar cylinders. This paper also provides reasoning for further volume and mass optimization of compressed hydrogen cylinders through the establishment of realistic cylinder usage parameters in standards. In particular, the overly conservative fill life requirement for cylinders is examined.

Jan 1, 2005

By Youngsoo Song, Hyunjung Kim, Junhyun Choi, Siyoung Q. Choi, Gahee Kim

In this study, for the first time, to confirm the effect of bacterial growth phase on the malachite flotation were investigated in a well-controlled Hallimond tube system. The test results showed that the bacteria in the stationary phase exhibit two-fold greater floatability than those in mid-exponential phase. To understand the observed flotation behavior, complementary cell characterization tests and cell attachment tests were conducted. Interestingly, the bacteria at both phases exhibited similar surface properties as well as almost identical amount of cells attached onto the malachite, suggesting that the growth phasedependent flotation behavior cannot be attributed to the variation of cell surface properties and the extent of cell adsorption. On the other hand, cell detachment tests revealed that the amount of cells detached from the malachite surface is greater for the mid-exponential phase than the stationary phase due to the higher fluid drag applied to the cells at the mid-exponential phase, which was explained by the differences in the size and shape of attached bacteria onto the malachite surface. These morphological characteristics were found to cause the bacteria of mid-exponential phase to be separated highly sensitive and easy from malachite surface due to the fluid flow. Second, scale-up selective bioflotation tests were carried out in a 1 L Denver cell in malachite–silica binary mixture systems. Through the tests, we optimized the cell concentration and the malachite fraction in the feed. Overall, high malachite selectively was observed under optimized conditions (both recovery and grade showed more than 90%). The trend was in agreement with classical DLVO interaction energy profiles, which show the relative magnitudes of the adhesive forces between the mineral and the attached cell under equal hydrodynamic conditions.

Jan 1, 2016

By V. G. Minenko, A. L. Samusev

For efficient leaching of gold from sulfide ores and the oxidation of sulfides into sulfates, it is necessary to introduce a substantial amount of oxidant - atomic oxygen, hydrogen peroxide, ozone, potassium or sodium hypochlorite. In this paper, hypochlorite electrochemical treatment is proposed as an effective method of intensification of refractory ore leaching. The objective of the study is to increase the gold recovery from refractory ores with the application of chlorinated solutions that are modified by chemical or electrochemical treatment. The advantages of the use of the modified chlorinated solutions instead of cyanide for gold-sulfide leaching are considered to be the following: a high concentration of the oxidizing agent (hypochlorite ions) in solution helps to achieve a high speed of gold dissolution in the form of chloride complexes; the possibility to produce hydrochloric acid solutions that may be used for the recovering gold by electrolysis; the possibility of the processing of carbonaceous, arsenic-bearing and others kinds of refractory gold ores. The mechanism of the interaction of the modified chlorine solutions with gold-bearing sulfides (pyrite and arsenopyrite) was investigated. The efficiency of the application of chemical and electrochemical leaching method was proved. The main factor that limits the rate of gold dissolution is a high concentration of sulfate ions (SO4 2-) formed in the solution by the oxidation of sulfide minerals. The optimal parameters of chemical and electrochemical leaching method and effective ways to remove sulfate ions were determined. The method helps to increase the level of the gold recovery up to 87% from refractory ores. The intensification of leaching by chemical and electrochemical treatment opens up opportunities for the creation of modern efficient and environmentally-friendly technologies that may be applied for gold extraction from refractory gold ores.

Jan 1, 2016