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By A. W. Johnston, R. E. Barrett

"The Central Patricia mine is in the greenstone belt north of lake Sc. Joseph in northwestern Ontario. It is 90 miles north of Allanwater on the Canadian National railway and 220 miles east of the Manitoba boundary. The unusual feature of the ore of this mine is that the gold does not occur in quartz but in sulphide minerals filling fractures in iron formation.AREAL GEOLOGYThe rocks of the area in which the mine occurs belong to the Early Precambrian. They consist · of andesite lavas and tuff interbedded with greywacke-like sediments and iron formation . A siliceous phase of the sediments lying north and south of the greywacke enclosing the ore-bearing iron formation in places resembles a sheared and sericitized quartz porphyry. This is shown in the legend of Fig. 1 as quartz porphyry and quartzite, but it is possible that the quartz porphyry-like phase is sediment. A northwest- striking dyke of diabase crosses the property 3,000 feet east of the shaft ( Fig. 1).IRON FORMATIONAlthough there are numerous bands of iron formation in the v1cm1ty of the mine, ore has been found to date in only one main and two lesser zones. The iron formation bands range in width from a few inches to 60 feet, and are interrupted along their strike by gaps that are parallel and rake to the east at about 65°. The iron formation is definitely banded and laminated."

Jan 1, 1954

By F. McIntosh Galbraith

EMPLOYING geophysics to find ore was for a long time considered by the Canadian mining fraternity to be a performance of dubious value: in a category somewhere between the practice of sorcery, and using a divining rod to locate underground water. With increasing knowledge, however, and with constantly improving instruments, a solid speaking acquaintance with this adolescent science is becoming an integral part of the mining geologist's stock in trade. And quite properly so: for, in the established mining districts, the ore deposits which could be easily found, by ordinary prospecting methods, have already been located. There remain; however, in almost all of the principal mining camps, areas which are covered to varying depths by glacial debris; and it is here that the obvious opportunities exist for the successful application of geophysical methods. Geophysical results must always be considered in the closest possible relation to the local geology; and, in reality, the 'doodle-bugs' are simply additional tools for the geologist (in the same category with a plane table or a microscope). The Sudbury Basin is a shining example of precisely this state of affairs. Detailed geological mapping has not significantly altered the position of the outer norite contact as placed on Dr. Coleman's original map of the district. What detailed examination has done, of course, has been to reveal the accuracy with which the contact can be placed in different parts of the district, and to show up, in consequence, areas in which further work might reasonably be expected to disclose hitherto unknown or unsuspected ore. Viewed in this light, the proportion of the norite contact which is covered by substantial quantities of overburden is astonishingly large.

Jan 1, 1939

By Matthew Violot

Vale Canada?s Birchtree Mine, located in Thompson Manitoba, has been experiencing problems with hanging wall / footwall dilution, as well as sloughing off of adjacent stopes and temporary stope block backs. Birchtree Mine is interested in determining how time affects the stability of their open stope blocks. Many factors simultaneously influence open stope stability (rock mass quality, joint condition, stress condition). This makes it challenging to determine the influence of a single parameter such as exposure time or stand-up time. This study focuses on determining the effect of exposure time on open stope dilution and combines stress analysis and empirical based approaches.

Jun 1, 2012

By T. R. Chari

The safe-level dilution of low-level radioactive wastes in large volumes of selected granular material is proposed as an alternative method of permanent waste disposal to current Canadian practice of concentration and encapsulation. Accepting the fact that a "background level" of radioactivity exists throughout the world, the authors feel that the concept of controlled dilution of radioactive wastes to a level in keeping with "background" is a plausible alternative to current thinking on the subject and is worthy of equal consideration.

Jan 1, 1979

By Brooke Clements

The Buffalo Head Hills region is located approximately 350 kilometres northwest of the city of Edmonton in northcentral Alberta (Figure 1). The Alberta diamond joint venture consisting of Ashton Mining of Canada Inc., Alberta Energy Company Ltd and Pure Gold Minerals Inc. began exploring for kimberlites in the Buffalo Head Hills region in late 1996. At the time, the Mountain Lake diatreme, located 200 kilometres to the southwest, was the only reported kimberlitic rock in Alberta (Leckie et al., 1997, Figure 1). Exploration efforts since 1996 have successfully identified a new diamondiferous kimberlite province in Canada.

May 1, 2001

By R. A. Payant, J. A. Finch

Under certain conditions of air and moisture, sulphide materials can spontaneously heat, or selfheat. The reaction mechanisms of self-heating are not well understood. Most previous work has involved pyrrhotite because it is the most reactive sulphide. The current work investigates the self-heating behavior of sulphide mixtures composed of sulphides other than pyrrhotite. The four studied sulphides were pyrite, chalcopyrite, sphalerite and galena. The rest-potential was measured for each. Binary mixtures formed as a 1 : 1 weight ratio were pyrite-galena, chalcopyrite-galena, pyrite-chalcopyrite and chalcopyrite-pyrite. The four sulphides and the binary mixtures were subjected to standard self-heating tests. The four individual sulphides did not self-heat. However, mixtures of pyrite-galena and chalcopyrite-galena with rest-potential difference (?E) >0.3 volts did self-heat while the mixtures of pyrite-chalcopyrite and chalcopyritesphalerite with rest-potential differences (?E) = 0.1 volts did not self-heat. The results demonstrate that when certain non self-heating sulphides are combined they can self-heat. A possible explanation based on galvanic interaction and formation of hydrogen sulphide as an intermediate product is discussed.

Jan 1, 2009

Productivity and efficiency of diesel-powered underground trucks and LHDs can be enhanced through the application of a range of advanced technologies. In addition, these machines are subject to ever more stringent emissions control requirements. This paper will review how various technologies can improve usability, maintainability, and performance of LHDs, through a number of examples. The use of instrumentation and monitoring to understand the role of operator practice on mucking efficiency, as well as the use of finite-element analysis to evaluate structural design, and the use of control techniques to modify operator inputs and hence decrease power consumption, will be presented.

May 1, 2002

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 Guichao Wang, Geoffrey M. Evans, Graeme J. Jameson

"In this paper we present a new method for studying the detachment of particles from bubbles in a rotating turbulent eddy. The eddy is formed in a wall cavity in a two-dimensional water tunnel with transparent walls. When water flows through the tunnel, a vortical flow field develops in the cavity. The properties of the eddy can be modulated by changing the free-stream velocity of the water in the tunnel. Bubbles are pre-loaded with one or more particles in a fluidized bed flotation device located beneath the vortex cavity. Loaded bubbles are released one at a time into the cavity, and the motion of the bubbleparticle aggregate is studied using a high-speed video camera. The diameters of the particles and the bubbles, and the number of particles initially attached to the bubble, can be varied. The trajectories taken by the bubbles are quite complicated. In some cases, the bubble moves to the centre of the eddy, and particles rotate around its axis. If the rotational speed is sufficient, particles may detach due to centrifugal force. However, other modes were observed, including inertial detachment due to rapid changes in direction of the surface of the bubble, because of changes in trajectory of the bubble as a whole, or because of pulsations and oscillations of the bubble surface. Clusters of bubbles held together by particles were seen to form and reform. In the traditional explanation for the detachment of particles in flotation cells, it is assumed that particles detach from bubbles rotating in an eddy due to centrifugal force (Schulze, 1977). Although the conditions assumed in Schulze's theory may exist, it is only one of a range of phenomena that can lead to the detachment of particles from bubbles in a turbulent vortex.INTRODUCTIONThe recovery of particles by flotation methods is dependent on the particle size. The recovery in the existing flotation machines reaches a peak for particle size, typically in the range of 20 to 100 µm. This size range varies as a function of the particle’s properties (type and composites). For coarser particles, the recovery drops very quickly (Gaudin, Groh & Henderson, 1931; Jowett, 1980). If the upper size limit can be increased for flotation, dramatic savings in the grinding energy can be achieved."

Jan 1, 2016

By W. J. Stickney

"Over-all recovery of cadmium has been increased at the plants of the Hudson Bay Mining and Smelting Co., Limited, since the construction of a slag fuming plant and baghouse where smelter flue dust is recovered. This pa-per outlines the distribution of the cadmium in plant products from the concentrator to the refining department.The leaching of cadmium-bearing precipitates from the zinc plant is also discussed. This consists of a two-stage leach; first with sulphuric acid and then with copper sulphate. Details of the leaches are outlined along with the safety measures practised in handling the hydrogen and arsine evolved.The paper describes the final preparation of electrolyte for the refining cells by purification for copper and thallium. Deposition of cadmium, using a polyacrylamide as an addition agent, is discussed.An outline is given of the melting procedures, under either sodium hydroxide or zinc chloride, and of the sub-sequent treatment of the dross to recover entrained cadmium and thallium."

Jan 1, 1966

By E. L. Martheleur

A general expression for the electric power generated or consumed in a direct-current circuit is obtained by multiplying the reading of a suitable voltmeter connected across the terminals by the reading of an ammeter connected in the circuit. by the reading of an ammeter connected in the circuit. When alternating currents are considered, the product of the volts and amperes as obtained for direct currents does not generally represent the true energy involved; it is greater than this true energy and should be multiplied by a certain factor which may have any value between zero and unity, according to the conditions of the circuit. This factor is called the power-factor of the system, and expresses the ratio of the true energy over the apparent energy. For a three-phase system the expression of the apparent energy is [\/ 3 x E x I; ] while the expression of the true energy, that is, energy suitable for mechanical work, is [v? 3 x E x I x cos A.] The total current of a circuit corresponds to the reading of an ammeter connected in the circuit; it is the resultant of two currents. The first of these is in phase with the voltage, and is that portion which really produces mechanical work; the second is always in quadrature with the voltage, that is it may lead or lag the voltage by 90° according to the condition of the circuit. This second current does not produce any sensible work, and for this reason is sometimes called wattless current or reactive current.

Jan 1, 1924

By S. Fabich

Since the very beginning of Polish copper mining, special consideration of sink shaft techniques through highly saturated Cenozoic rocks was required. Shaft freezing has been chosen as a method to consolidate these rocks. Due to the rock mass structure and water inflow potential, shaft sinking without freezing was considered dangerous. In the course of time, rock mass freezing technology and experience were evolved and this technology became safer and more reliable. New techniques appeared not only in the technical method of freezing, but also in the matter of designing. Computer aided techniques allow engineers to make a detailed analysis and view of freeze wall development. Nevertheless it is important to determine basic thermal rock properties. In this paper, the evolution of knowledge and engineering experience taken in Polish copper mines and current knowledge level in that matter were shown.

Aug 1, 2013

By Jin Li

The tensile properties and microstructure of AZ91 Mg alloy before and after equal channel angular extrusion (ECAE), and the fracture behavior during tensile testing for as-extrusion and ECAE AZ91 were investigated. The alloy was performed ECAE from one to eight passes at 498K. The elongation decreased with the pass number increasing after ECAE. Grains were refined, partial coarse ß-Mg17Al12 phase fell to pieces, fine ß-Mg17Al12 precipitated in the AZ91 Mg alloy after ECAE. During tensile test the a-Mg/ ß-Mg17Al12, a-Mg/Al8Mn5 interface and the grain boundaries in a-Mg matrix acted as the crack initiation sources. The frequency of micro-cracks at the a-Mg/ß-Mg17Al12 interfaces and grain boundaries increased after ECAE, which accelerated the growth and coalescence of the micro-cracks during tensile test and resulted in the decrease of elongation of AZ91 Mg alloy by ECAE.

Jan 1, 2006

By R. Chen, K. Xia

In deep mining activities, blasting induced compressive stress wave would be reflected as tensile wave at a free surface around the openings, which would facilitate the tensile failure of the deep rock since it is much weaker in tension than in compression. It is thus critical to understand the dynamic tensile failure of rocks subjected to static tension for deep rock engineering applications. A modified split Hopkinson pressure bar (SHPB) system is adopted to load Brazilian disc (BD) samples statically, and then exert dynamic load to the sample through stress wave generated by impact. The pulse shaper technique is used to generate a slowly rising stress wave and thus to facilitate the stress equilibrium of samples during each test. Five groups of Laurentian granite (with tensile strength of 12.8 MPa) BD samples under the pretension stress of 0 MPa, 2 MPa, 4 MPa, 8 MPa, and 10 MPa are tested under different loading rates. The result shows that the dynamic tensile strength of the rock decreases with the increase of pre-tension stress, which is easy to understand because pre-tension stress weakens the rock sample. It is also observed that under the same pre-tension stress, the dynamic tensile strength increases with the loading rate, revealing the so-called rate dependency that is common for engineering materials. Furthermore, it is found that the loading rate sensitivity of the rock increases with the increase of pre-tension stress. A qualitative explanation for this phenomenon is that more microcracks are generated and activated under higher pretension stress, resulting in a more viscous material. Based on the results, an empirical equation is proposed to fit the data and explain the dynamic tensile behaviour of rock under pre-tension stress. A physical model is used to simulate the dependency of the dynamic tensile strength of rock on the pre-tension stress and the loading rate, which is shown to be in good agreement with the experimental results.

Jan 1, 2015

By Jose Alberto Gonzalez, Said Sharif Mahboob, Jeffrey L. Shepherd

"During the industrial electrowinning of zinc, uneven growth can cause short-circuits and make the deposits more sensitive to the presence of impurities that can significantly impact current efficiency. To produce levelled zinc deposits, additives such as glue, licorice and sodium silicate are often added to the electrolyte. Even in the presence of additives, uneven zinc growth still takes place because of the combination of hydrodynamic and electrolysis conditions in the cell house. Recent advancements in imaging spectroscopy and scaling analysis have opened an avenue to further study the effects of additives on zinc growth morphology. In this study, Atomic Force Microscopy (AFM) and scaling analysis have been used to monitor zinc growth characteristics including roughness, periodicity, aspect ratios and growth mechanisms as a function of electrolyte composition as well as deposition time. Zinc was electrodeposited from an industrial electrolyte containing a host of additives onto an aluminum cathode with a platinum wire serving as the anode. AFM images of the samples were collected to obtain 3D topographical information on which scaling analysis was performed to extract details on root-mean-squared (rms) roughness, periodicity (grain size), aspect ratio of surface features and growth mechanism. This analysis provided information on the mechanism by which the previously mentioned variables can impact short term growth and also provided a prediction of expected growth at long deposition times.INTRODUCTIONElectrowinning is one of the final stages in the industrial production of zinc metal. It is during this process where dissolved zinc ions undergo electro-reduction from an acidic electrolyte onto an aluminum cathode and are later recovered by stripping the zinc metal from the substrate. However, due to the nature of zinc growth as well as the various operating conditions, zinc deposition may occur unevenly, sometimes causing short-circuits that can cause electrode damage and reduced zinc production."

Jan 1, 2016

By Neda Zangeneh

Production efficiency from low permeability gas shales require techniques to optimize hydraulic fracture completions. One completion strategy involves the simultaneous or near simultaneous hydraulic fracturing of multiple horizontal wells to maximize the fracture network area and stimulated reservoir volume. However, changes to the in-situ stress field caused by an earlier hydrofrac on subsequent hydraulic fractures are not accounted for in traditional hydrofrac design calculations. Presented here are the results from a set of transient, coupled hydro-mechanical simulations of a rock mass containing two wellbores using the discontinuum-based distinct-element method. The results demonstrate the influence of stress-shadows generated by a hydraulic fracture on the development of subsequent hydrofracs from an adjacent well. It is shown here that these interactions have the potential to change the size and effectiveness of the hydraulic fracture stimulation by changing the extent of the hydraulic fracture around the secondary well.

Jun 1, 2012

By David Stone

The Beal Mountain Mine near Anaconda, MT is an interesting case history of a mine that has continued operations despite several large pit wall failures over a period of about 10 years. The largest event involved some 3.9 million tons of rock that has moved steadily at a rate of about 0.05 ft/day since 1992. This paper documents the geotechnical instrumentation and monitoring programs implemented at Beal to provide the company with a comfortable baseline that supported ongoing operations. The success and failure of a variety of stabilization measures will be discussed, along with typical instrumentation responses for several significant events. The success of Beal Mountain serves as a good model for mines faced with serious geotechnical challenges.

May 1, 2001

By C. I. Walker

Field tests at a number of large mineral processing operations have been undertaken to better understand the wear life impact of different aspects of pump design, materials of construction and maintenance procedures. Data are presented for wear rates, and typical result variability is explored. To improve the availability of pumping equipment in a milling circuit it is not only important to improve the wear life, but also reduce the variability in the wear life of components so that the incidence of premature failure is lessened. Localised gouging wear due to flow separation and turbulent eddy formation is often the point at which part-holing occurs. A number of improvements to the design of pump impeller and throatbush (suction side liners) to reduce the localised gouging wear are outlined. Also, results are presented on the use of composite materials (mix of metal, rubber and ceramic) for throatbush materials to protect specific areas against wear.

Jan 1, 2012

By Somasundaran P., M. Vasudevan, Z. Dai, D. R. Nagaraj, T. Bhambani, P. Patra

Historically, efficient beneficiation of ultramafic ores has been challenging, partly due to a lack of clear scientific understanding of the effects of Mg silicates, particularly fibrous serpentines, on selective Ni recovery. Recent research at Columbia-Cytec as a part of a Vale JDP project has led to new insights into the mechanistic aspects of the adverse effects of Mg silicates. Our research has provided strong evidence to support the hypothesis that the adverse effects of Mg silicates are mediated through their large influence on pulp rheological properties, far more than any other pathway. The severity of the effect of Mg silicates is predominantly dependent on the aspect ratios of Mg silicates. For example, the pulp viscosity increases dramatically with increase in the fibrous nature of the gangue mineral leading to poor Ni separation. Various ways by which the suspension rheology affects flotation sub-processes, with implications for remedy are discussed. The insights and results have served to develop (or construct) a phenomenological model to adequately explain all of the ore flotation data, particularly the Mg silicate transport to the froth phase and the concentrate.

Jan 1, 2011

By N. Sarmady, Mei Li, N. C. Parson, W. J. Poole

"The mechanical behaviour of AA6082 is a function of the extrusion conditions and in particular, the quench rate after extrusion. It is well known that precipitation of Mg-Si phases on grain boundaries during quenching can negatively affect the ductility of the alloy. In this study, AA6082 alloys containing 0.5 wt. % Mn and 0.15 wt. % Cr were direct chill (DC) cast, homogenized and then extruded to produce 3 mm x 42 mm strips. The microstructure in the as-extruded strips was unrecrystallized due to the Zener-Smith drag from the Mn/Cr dispersoids. It was shown that a solution treatment of 5 minutes at 560°C did not significantly affecting the as-extruded microstructure but if the as-extruded strip was cold rolled prior to heating, recrystallization occurred concurrently with the solution treatment. As such, 3 initial microstructures were produced, i.e. unrecrystallized and recrystallized with a grain size of 9 and 40 µm. After the solution treatment, controlled cooling experiments were conducted using the Gleeble 3500 thermomechanical simulator with cooling rates of 10, 25, 80°C/s as well as water quenched. The mechanical properties (e.g. yield stress, fracture stress and fracture strain) were determined from tensile tests for the different combinations of initial microstructure and cooling rate. The relationship between the quench rate and precipitation of Mg-Si phases on grain boundaries was examined by FEG-SEM. It was found that the yield stress decreased as the cooling rate decreased and that there was complex relationship between the fracture properties and the microstructure.INTRODUCTION As the automotive industry strives to reduce fuel consumption and CO2 emissions with the goal of reducing the environmental impact, there is a need for lighter vehicles. As a result, aluminum alloys are gaining popularity to replace steel parts as structural components. An exemplar of this is the Ford F-150 pickup truck which has an aluminum body and is ˜750 pounds lighter than the previous steel version of the vehicle. The structure includes a mix of aluminum sheet, extrusions and cast alloys. The current research is concerned with the performance of aluminum extrusions in applications such as side rails, crash tubes and other structural parts. These components experience a combination of bending, stretching and folding both during the forming of the part and in service, e.g. crash of a vehicle. There is a need to have detailed information on the influence of processing on final material performance, in particular the cooling rate after extrusion."

Jan 1, 2018