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By F. H. Samuel, J. E. Gruzleski, S. Valtierra, H. W. Doty, F. J. Tavitas-Medrano

319-type cast Al-Si-Cu-Mg alloys are commercially important due to their popular use in automotive applications. Artificial aging heat treatments are commonly performed in these alloys to achieve precipitation hardening and, therefore, improve their mechanical properties. The present work was carried out to investigate the effect of conventional (at a constant temperature, as specified by the standard T6 heat treatment regime), and non-conventional multi-temperature and interrupted aging cycles on the hardness, tensile and impact properties of two 319-type alloys (with and without Sr+ Mg additions). The results show that certain multi-temperature aging cycles have a more favourable effect in improving some mechanical properties than conventional cycles.

Jan 1, 2006

By Fei Dai

Musculoskeletal disorders (MSDs) are a group of painful disorders that affect muscles, tendons, nerves, joints, cartilage, and ligaments. They are a serious problem among the workforce in the United States. In the construction industry, high physically demanding tasks expose construction workers to a number of well recognized MSDs risk factors such as repetitive motion, high force exertion, and awkward body posture. Finding ways to effectively identify and evaluate risks of MSDs can significantly alleviate this problem. To this end, this paper reviews state of practice and research in the assessment of risks of MSDs among construction workers, in which a number of biomechanical models have been developed to evaluate joint and tissue loading with the aid of state-of-the-art remote sensing technologies. Findings from the review reveal that despite the advances in tracking human motion and muscle activities, current remote sensing approaches still involve sophisticated instrumentation and expensive experiment setup. These factors greatly limited the applicability of such approaches in real construction settings. How can we detect and evaluate the construction worker?s MSDs risk in real work environments? In this paper, strategies by utilizing video surveillance systems are presented, to set the stage for addressing the above question and discussing future research in real-time, marker-less, and costeffective MSDs risk assessment.

Aug 1, 2013

By K. A. Foxford, D. A. Polya, R. P. B. Hebblethwaite

"Abstract-A variety of techniques for interpreting systems of mineralized echelon veins is discussed using examples from Panasqueira and SW England. As aids for exploration and mine planning, and as a tool for ore reserve evaluation, particular emphasis is placed upon establishing vein morphology in the third dimension, and upon understanding vein dilation and propagation histories. Special attention is also placed upon investigating vein thickness and spacing relationships, and upon understanding vein segmentation. The relevant data for these techniques are all readily obtainable from stope and core sources.The vein systems described were produced in host-rock sequences that underwent incremental dilation in response to fluid overpressures, and individual veins display evidence for mineral infilling synchronous with their propagation. Echelon vein geometries resemble those reported from igneous dikes and sills: vein walls are stepped and veins are divided into segments arranged in echelons. Changes in vein geometry, from arrays to composite structures, reflect both the evolution of the vein system with time, and the changes occurring between the margins (arrays) and core (composite structures) of the system. These characteristic morphologies can be used to infer vein propagation and fluid injection trends, proximity of neighboring veins, and the shape of the system as a whole. The techniques are applicable to systems of echelon veins produced under tensile conditions in rocks where faults were absent at the time of vein formation, and where subsequent deformation has been minimal. Further work is required to assess the application to echelon vein systems formed within more complex tectonic regimes."

Jan 1, 1995

The University of New South Wales (UNSW) has been a world leader in the development of innovative virtual reality technologies over the last 10 to 15 years. These developments have included developing the world?s first 360° surround, virtual reality (VR), stereo projection theatre system known as AVIE (Advanced Visualisation and Interactive Environment), which was developed by iCinema, a collaborative venture between the UNSW Faculties of Engineering and College of Fine Arts. The UNSW School of Mining Engineering has been responsible for development of mining applications virtual reality software modules and to date, has developed eighteen different mine safety training and mining engineering education modules which run in the AVIE environment. This platform and technology package provides a unique ?immersive environment? experience for groups of trainees or students who can engage with the simulated environment in the complete safety of the virtual reality theatre. In all of the major international mining industries, safety is of paramount importance, and training of personnel is an essential component of any comprehensive proactive safety management system. All personnel need to be aware of the inevitable hazards around them at all times, as well as understand appropriate safety and operational procedures. This can be done by conventional class-room style training sessions, or by provision of training documentation. However the effectiveness of such systems is often very limited due to the inability of trainers to engage with the audience for a lengthy period of time; or to convey the often complex and variable mining environments and situations which can exist in a typical mine. The ability to immerse the trainees in a virtual mine environment, with all the reality of an actual mine but with none of the physical exposure to actual hazards, provides a far more effective and engaging training experience. Furthermore, in the virtual world, trainees can be exposed to the very unlikely, but nevertheless high consequence hazards such as mine fires, falls of ground or outbursts, without any risk to their safety and well-being. The end result is that trainees will be far more engaged with the learning environment they find themselves in, and will develop a far higher level of understanding of the topics, rather than simply experiencing a passive class-room style learning environment offered by conventional training modes. The UNSW systems have been implemented widely within the Australian mining industry and the mining engineering education sector and are now being adopted internationally. This paper presents an overview of the innovative technologies involved in these virtual reality systems ? as applied to the mining industry. Modules developed for both mineworker training and mining engineering student learning will be presented, to illustrate the effectiveness and value of such a training and education approach.

Aug 1, 2013

By C. S. Gibson

INTRODUCTION I WELCOME the opportunity to speak on Programmes in Safety. The invitation to do so shows that those guiding affairs of the Institute in this District realize the practical importance of this subject. My remarks are intended primarily for mines having 100 to 400 employees, approximately. With minor modifications, however, they apply also to larger or smaller operations. Others, I hope, will derive benefit from this paper, for they, too, have a part to play in accident prevention; for example, contractors such as shaft-sinkers; manufacturers of equipment; and consultants and designers of mining, milling, and metallurgical methods. These troubled times stress, as never before, the importance of efficient operations in mining. The days are gone when neglect can be afforded. Safe working conditions and satisfied employees are essential for efficient production at reasonable cost. The mining industry of Ontario long has been keenly aware of the human aspects of this subject, and as a whole it has done much to decrease the frequency and severity of disabling accidents. The number of fatalities per 1,000 employees has been reduced from a high of 5 some two decades ago to an all-time low of 0.89 in 1948; the incidence was slightly higher in 1949, being 1.17 per 1,000. The reduction in non-fatal compensable accidents also has been outstanding, frequency having ?been reduced from over 200 per 1,000 employees some two decades ago to 54 per 1,000 at the producing mines in 1949. These statistics demonstrate progress. Nevertheless, the general picture still leaves much to be desired when viewed from two other angles.

Jan 1, 1951

By I. M. Marshall

A review of technical literature covering Canadian mining emphasizes the advancement and changes that have been made in mining practice. However, current technical publications rarely outline basic principles or state definite rules that govern profitable mine operation. it may be argued that the broad principles of mining have long a go been outlined in various handbooks, text-books, and periodicals, and that these principles never alter. This is in great part true, but modern machinery, improved meta1-lurgical practice, and other advances, have in part modified these principles or changed the manner of their application. Many engineers hesitate to state specific rules, because it is so easy to quote an exception to a rules that any such statement appears to lose weight upon its very utterance. The exception to rules, and the reluctance to formulate rules, has forced such maxims as "the only rule in mining is the point of a pick," and "gold is where you find it". As an illustration of rules and their exceptions, one might quote the time-honoured maxim that a mill should not be built before a shaft has been sunk on a property in point of fact, Canadian mining history is replete with examples of wasted capital where a mill was built before a shaft had been bottomed. Y et this past year has seen a property enter profitable production whereon the building of the mill was started before the shaft was sunk. Instances such as this should not be accepted as evidence that a rule has been overthrown, but rather as an exception to the rule. The case cited pays tribute to the application of the diamond-drill combined with the correlation of sound geology. Incidentally, both these features emphasize a modern trend in the development of Canadian mining properties-a trend that is perhaps worthy of further comment. It is such trends that affect the principles of mining or modify their application. It is with such that this paper deals, at ]east in part. It is hoped that the statement of principles and the opinions herein outlined will be of sufficient interest to arouse discussion.

Jan 1, 1939

A mathematical model of a decision is represented by the table in Figure 4. The numbers in the matrix are a measure of the effectiveness of each alternate for an objective. In this case, it is the per cent of desired profit that is satisfied by each alternate for each objective. By adding all of the values in a row, we have a measure of which alternative is best for both objectives. However, if you think that alternate 1 is necessarily better than alternate 2, you are wrong. Why? Because the weight of the objectives may not be equal. It could just be that this plant can sell more than it can produce, so that the loss in profit represented by increased sales is more than twice as important as reductions in costs. (See Figure 5). In that case, let us weigh objective 1 as 30 per cent and objective 2 as 70 per cent. It must also be obvious that the sum of all the "objective weights" must equal 100 per cent. Now, by evaluating our alternates according to their weights. we find that alternate 2 is better than alternate

Jan 1, 1964

By Maureen McGuiness

"The pastefill circuit at the Bell Allard Mine in Matagami, Quebec started up in August 1999. The surface pastefill plant produces a cemented paste which is sent underground by gravity through a vertical pipeline in the mine ventilation shaft. Difficulties with paste flow during the start-up highlighted the importance of understanding paste rheology and the effect of operating procedures on line wear. By June 2000, the original circuit had been modified to include a paste pump to transport the paste to the shaft.The steps taken during the paste plant commissioning are discussed. The final flow sheet is presented, focussing on the use of instrumentation to ensure full column flow and proper distribution underground. Resistance modelling and accelerated curing of samples are examined as possible ways of predicting paste resistance to ensure compliance with the mine’s paste specifications.INTRODUCTIONCommissioning a new plant can be difficult and time consuming. The start-up of Noranda’s Bell Allard paste backfill plant was no exception. Since the first day it went into operation, the paste circuit could not meet the tonnage and paste quality requirements of the mine because the paste would not flow by gravity into the vertical pipeline in the mine’s ventilation shaft.Diagnosis of the pastefill problems proved difficult. It was only when the rheology of the Bell Allard paste was understood that the flow problems were solved. To ensure that the paste placed in the stopes meets mine requirements, two methods of paste resistance prediction are being developed."

Jan 1, 2002

By Laxman M. Amaratunga, Nuri Hrnidi

"Reactive pyrrhotite tailings were agglomerated using the Cold Bond Tailings Agglomeration (CBTA) process with low cost binders; Portland Cement and fly ash. Various chemical additives, were used to retard acid mine drainage (AMD), including acid neutralizers, surfactants, sealants, and bactericides, which were encapsulated into the agglomerates. The choice of these additives was based on their low cost, low toxicity, and environmental friendliness. The main objective of the study was to examine the long term stability of these reactive tailings agglomerates towards AMD when used as aggregates for disposal in underground paste backfill.A carefully controlled kinetic stability test was carried out using specially designed humidity cells suitable for testing pellets. Using the humidity cell test method a 20-30 year AMD test may be accelerated to 50 weeks. During this period the following parameters were monitored: pH, redox potential, conductivity, sulphate, acidity, and dissolved metals.Results indicated that most of the encapsulated additives were successful in retarding AMD, while the control samples produced significant amounts of acid generation. The water soluble surfactant Enviroseal, and the sodium silicate sealant were very effective as a long term retardant for acid generation reactions in the sulphidic tailings when exposed to oxygen, water and iron-oxidizing bacteria.IntroductionThe sulphidic material discharged from concentrators becomes reactive upon exposure to air and/or water. Pyrrhotite (Fe0 S0_1) and pyrite tailings in particular which are discharged from the beneficiation process in the mining and mineral processing activities consist of finely ground particles. Upon exposure to oxygen and moisture, the tailings become reactive due to the instability of the metal sulphide minerals present which undergo spontaneous oxidation, thereby producing a weak sulphuric acid. Therefore, the long-term behaviour of the tailings can have a significant impact on the environment, due to acid mine drainage (AMD). AMD is created during natural atmospheric weathering when leaching action (natural and bacterial) conditions are present in the process wastes discarded during the mining and milling of sulphur bearing ores, and consequently it plays a major role in surface water chemistry."

Jan 1, 1998

By A. L. McAllister

"MASSIVE sulphide deposits are found in two areas of New Brunswick, the St. Stephen area and the Bathurst-Newcastle area. In both, the geology in the immediate vicinity of the sulphide bodies is largely inferred from drilling results as outcrop is not plentiful and is, in fact, almost lacking in most places. With few exceptions these deposits have not been explored by underground methods. Consequently much of the. detail on the geology will only become known over a period of years as economic conditions make mining feasible.Much of the information contained in this paper has been supplied directly by company geologists. As a result of the number of contributors, some confusion of nomenclature bas to be anticipated. Cross-sections and plans of the individual deposits are, in most cases, as supplied by the companies concerned. Most of the interpretations are the responsibility of the author."

Jan 1, 1960

"Since all gold mills must sooner or later be cleaned up for permanent shutdown it was felt that a record of what was done at one mill might be of some help to those who will have to do the same job in the future,In cleaning up the mill of Delnite Mines Limited, I had an advantage that most mill superintendents will not have in that I started up the mill and was there until it was shut down, It was also known for two years approximately when the shutdown would be and for a year almost the exact time. This, of course, made careful planning possible and enabled me to get advance information that wouldn't have been available had the shutdown come unexpectedly,Early in 1964 calculation of ore reserves and the known number of working places available indicated that the mine would run out of ore sometime in August or September but not later than October, The time of course would vary with the number of competent miners that could be retained until the shutdown. Since the mining method used exclusively on the ore then remaining was cut and fill, it was known that once mining operations ceased it would require at most two days to crush and grind the last of the ore.In March 1 964 I took samples of the concrete floor under the precipitation presses, in the flux room and furnace room of the refinery and from the assays obtained proved that there would be no profit in breaking up the concrete to recover the gold from it, Samples taken from the top half inch of the concrete floors assayed less than 0, 10 oz per ton,"

Jan 1, 1966

Despite the claims of energy efficiency and the considerable development that has gone into dramatically extending rolls? life and facilitating rolls? change-out, in the six years since the last SAG conference, only a few HPGR operations have entered the realm of mineral processing. Risk barriers to the take-up of new equipment or processes are: a massive increase in materials handling issues as well as in the number of pieces of equipment required, low total circuit potential energy savings, and similar or higher capital costs. An alternative route is to make use of the complementary strengths of the HPGR and SAG in hybrid circuits. Minimising materials handling issues, providing an ideal balanced feed to the AG or SAG mill, and improving controllability through shifting grinding load as the RoM feed changes, are all potential major advantages to this approach. Conceptual circuit layouts, based on real measured ore and equipment data, are presented here to illustrate the potential production upside, the reduction in operating costs and the reduction in the physical and energy footprints.

Jan 1, 2012

By N. Gharib, F. Hassani, P. Nekoovaght

"Novel rock breakage techniques are becoming more viable and attractive to industry. Microwave energy, as a thermal energy capable of inducing micro cracks through differential heating (therefore expansion) is a technology gaining considerable attention in mineral processing and ore comminution applications. Recently, the use of microwave radiation has been evaluated as a possible avenue for terrestrial and extra-terrestrial drilling applications as well as full face tunneling or rock breaking machines. As part of an overall research on use of microwave in rock breaking systems, the influence of microwave energy on the mechanical properties of common hard rock types as basalt has been investigated. The results revealed that microwave energy irradiation imposes micro and macro cracks to the surface of the rock being irradiated. In explosive free tunneling applications using TBM, jointed and cracked surface of rock eases the cutting process and increases penetration rate. The experimental setups have been simulated with the help of a multi-physics numerical modeling and the results have been compared with practical experiment. The wave propagation of microwave has been simulated and the distances where the power intensity is higher are identified. Experimental and simulation results underlined the potential impact of the use of microwave energy in underground or surface excavation applications such as mining and tunneling. This will also contribute economically when mine-to-mill operation is fully considered to improve the efficiency of rock crusher stages. INTRODUCTIONDuring hard rock breakage (i.e., separation of a piece of a rock from its parent deposit) in mining and civil applications, the performance of mechanical equipment such as tunnel boring machines (TBMs) is limited by high levels of bit wear and maintenance. Preweakening natural rock prior to breaking it by machine is one approach to lower bit wear and maintenance costs. Some preweakening methods apply heat directly or indirectly. For example, flame torch-assisted TBMs (Lauriello et al., 1974; Resource Technology, 1984) have been deemed economical in terms of equipment, but their feasibility is limited by high fuel consumption. Microwave energy could offer several advantages over the flame torch method: it does not produce emissions or increase fuel consumption (electricity source is available on the machine), and is easy to control (quick power on and off)."

Jan 1, 2015

By Farzad Khodabakhshi, Adrian P. Gerlich

"In this article, cold spraying process was utilized to coat the surface of AZ31 magnesium alloy with a layer of AA7075 aluminum alloy. Thereafter, friction-stir processing (FSP) was employed to enhance the microstructure and consolidate the deposited layer. The grain structure and phase morphology were studied along with indentation hardness before and after cold spraying and friction stir processing. The magnesium substrate had an initial hardness of 74 HV which increased to 102 HV after FSP due to refinement of grains to <2 µm. The aluminum coating layer, provided improved surface hardness up to 160 HV, which further increased to 173 HV after FSP was applied.INTRODUCTION Cold spray is a material deposition process which can be used for surface modification, since it deposits material on a metallic substrate with little heating by way of high velocity ballistic impacts. Using cold spray technology, it is possible to deposit a wide range of coatings with various thicknesses by controlling the characteristics of the feeding powder and metal substrate, gas temperature, gas pressure, powder feeding rate, nozzle geometry, and gun traverse velocity. This process has been recently employed for surface modification in various aircraft and automobile structural applications. This has led to a broad range of research using this process for production and modification of different metallic and non-metallic systems. In the present study, cold spray process was used to deposit a uniform layer of aluminum-zinc alloy (AA7075) on the surface of AZ31 magnesium alloy. This coating was subsequently treated by way of friction-stir processing (FSP) as a new post-spraying modification technique to enhance the structural homogeneity and densification of the coated aluminum layer. This method utilizes a non-consumable rotating tool with a specially designed shoulder and pin that is plunged into the surface of metal to be modified and then moved along the direction of interest. The localized frictional heating between the rotating tool and workpiece leads to softening of the materials around the pin, and material extrusion through a complex flow of material from the advancing toward the retreating side the tool. To the author’s best knowledge, only a few reports discuss the modification of a cold sprayed deposit by FSP process. The microstructure and mechanical properties of the cold sprayed layer and substrate before and after FSP modification were examined using optical observations (OM) and indentation hardness testing. Furthermore, the AZ31 alloy substrate alone was treated with FSP as well, for the aim of comparison to the processed coating."

Jan 1, 2017

By A. J. Hyett

Due to the ongoing revolution in electronics and communications more cost-effective geotechnical instruments can be manufactured using digital technology. This new generation of digital instruments have embedded microcontrollers that provide highly accurate and reliable measurement of geotechnical behaviour in real world units that can be immediately interpreted. Digital measurements can be transmitted across existing mine-wide wireless communication networks, interfaced directly with infra-red enabled PDA?s or PC?s, and parsed to memory by low-cost data-loggers.

Apr 1, 2005

By Nur Hossain

Analysis of Linear Elastic Fracture Mechanics (LEFM) parameters via the Virtual Crack Closure Technique (VCCT) has been obtained for SENT specimens of AM6OB magnesium alloy. It is found that the ratio of initial crack length to initial monotonic plastic zone size is one of the critical factors in establishing the limit of using LEFM concepts. If this ratio is below a certain limit (i.e. when crack lengths are small in comparison to the plastic zone size), loss of similitude stress intensity factor range would occur. This ratio, therefore describes the limit below which the use of LEFM would no longer be admissible. In this study, the above limit was established for AM6OB magnesium alloy. In addition, fatigue crack propagation tests were conducted to ascertain the fatigue response of the alloy and determination of the coefficients of Paris model.

Jan 1, 2010

By W. D. Breil, C. B. Ison

A collection of general performance data relating to the G.H.H. - Gutehoffnungshiitte multi-rope friction hoist will be discussed together with some aspects of the following: overspeed supervision by a pantam device as opposed to the lilly type of fly ball control, automatic control systems, multi-disc braking, generator and motor winding, constant temperature monitoring, the development of an automatic hoist-rope lubrication system, and the control of rope tensions by the installation of G.H.H. - Gutehoffnungshiitte hoist rope fine tensioning units.

Jan 1, 1972

By V. I. Lakshmanan

Recycling helps to save energy and is good for the environment. It is also important for preserving the limited natural resources. In addition, recycling creates economic benefits and frees up space at the landfill sites. Process Research Ortech Inc. (PRO) has conducted extensive testwork in the area of waste processing and recycling. A process was developed for the recovery of Zinc from galvanized steel by alkaline leaching followed by solvent extraction and electrowinning. Extensive testwork has been conducted at PRO to obtain a useful by-product from rice husk. Rice husk was combusted in a gas/solid reactor to obtain an environmentally acceptable amorphous silica ash suitable for use in high strength concrete. In another development, vanadium was recovered from fly ash by separating carbon first, followed by alkaline pressure leaching, solvent extraction and precipitation. PRO has also developed an environment friendly process for treatment of industrial wastewater for its reuse to obtain zero or minimal effluent discharge. In this paper, four case studies related to recycling of zinc scrap, controlled combustion of rice husk, processing of fly ash, and reuse of waste water will be discussed.

Jan 1, 2011

By Jamel Sgaoula

During 1998 COGEMA Resources Inc. announced that operations at the Cluff Lake mine will be suspended indefinitely by the end of year 2000 as a result of deteriorating uranium market conditions. To remain profitable, Cluff Lake mine started an aggressive cost reduction program. A cost reduction team was formed to look for ways to lower production costs. The focus of this team was to screen all areas and to come up with ideas to improve the economy of the mine and ensure the viability of the operations over the remaining three years of operations. Among the areas where significant savings were achieved are: (1) replacement of portion of cement with fly ash in backfill; (2) backfill optimization; and (3) new shotcrete plant installation on site for bulk in-house shotcrete production. This paper details the research work carried out by Cluff Lake mine on these projects and results of its application.

May 1, 2001

By W. J. Przybylowicz, V. M. Prozesky, D. de Bruin

"The common style of gold mineralization in the Basal Reef and other auriferous conglomerates of the Witwatersrand Supergroup comprises clusters of gold grains occurring interstitially to quartz and pyrite pebbles as well as gold accumulations attached to the surface of and infilling hairline cracks and fractures in round, compact, detrital pyrite. The latter textural association is generally interpreted as a result of remobilization of originally detrital gold during regional metamorphism and related hydrothermal fluid circulation. There is general agreement that, although gold solubility was low, ore modification occurred during the metahydrothermal event, but uncertainty exists about the magnitude and scale of gold remobilization.Micro-textural and chemical investigation of compact round pyrite and associated gold accumulation has established that gold is preferentially deposited on chemically heterogeneous pyrite surfaces. Combinations of alternating high- and low-As zones in pyrite result in mixed np-type conductivity accompanied by electron exchange and the reduction-driven deposition of gold at the cathode. This model does not explain gold accumulations which are not immediately linked to chemical heterogeneities and it is inferred that an additional control on the deposition of gold was exerted by physical defects which lead to zones of increased charge density and/or areas of focussed conductivity. The inferred precipitation mechanisms suggest that submicrocopic physical and chemical controls are the important factors that determined the sites of gold nucleation and that precipitation mechanisms based on physicochemical changes of the hydrothermal system were not involved. The Basal Reef contains on average close to 5OJo of round, detrital, chemically zoned pyrite which provides a large number of electrochemically active pyrite surfaces. The extremely effective electrochemical precipi- . tation mechanism together with the low solubility of gold in Witwatersrand fluids is the main reason for the spatially restricted remobilization of gold in the conglomerate reefs."

Jan 1, 1994