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By J. A. Allan

"The history of the development and application of controlled recirculation systems in U.K. collieries is traced and the theory behind such systems briefly examined. Specific applications for dealing with dust and dust/heat problems in headings, for which practical experience is currently available, are described. Consideration is given to the special features which these systems introduce in the underground situation and to the essential safeguards which are required for their safe use.IntroductionRecirculation of air is a commonly used technique in genera l ventilation and air conditioning practice, but has always been regarded with some suspicion for mining applications. This is perfectly understandable in view o f the hazardous conditions which can occur with dangerous forms of recirculation in mines. However, certain controlled recirculation techniques can offer advantages, particularly in the field s of dust and climate control in headings, provided that they are designed, Installed an d managed with full comprehension o f all aspects of the system and always bearing in mind that from the point of view of serious firedamp ignition risk, headings are potentially the most hazardous places in coal mines.BackgroundProbably the first recorded use of deliberate recirculation in British collieries was reported by Lawton in 1933. This researcher described trials, undertaken under the auspices of a national committee on ""The Control of Atmospheric Conditions in Hot and Deep Mines"", involving attempts to increase the velocity, and thereby the cooling power on hot faces, by means of simple recirculation systems using fans and ducts delivering recirculated air in the opposite direction to the normal face airflow. No significant cooling advantage was obtained and there is no subsequent record of this work being continued. During the discussion on this paper, there was considerable disbelief that fire damp percentages had not increased significantly when air was recirculated, but apparently no attempt was made to establish why this should be. It is of interest to note that J. Ivon Graham, one of the contributors, recommended that recirculation should be tried in stone headings for the control o f dust, as he believed that ""there may be scope for recirculation and filtration of the air under certain circumstances in such headings"". This idea was not developed for another forty years."

Jan 1, 1983

By A Falter

Gyroscopic surveying instruments, which apply the physical law of a gyroscope, are being used for deter-mining the azimuth of lines with a high degree of ac-curacy. In the past ten years, gyro-theodolites have been introduced widely for underground orientation in the mining industry of Russia, Germany and South Africa. Gyroscorpic methods eliminate awkward procedures of conventional shaft plumbing, and provide more safety, excellent control and the highest precision at any point under-ground without interference with hoisting operations. The advantages of gyroscopic orientation in geodetic surveys become obvious in primary and secondary triangulation, in the determination of co-ordinates of single triangulation points, using the method of trigonometric re-section and intersection, and when traversing over long distances or in areas with obstructed view. Other fields of application are found in geophysical surveys and in the orientation of technical objects; e.g. radar stations, relay stations and ballistic missiles.

Jan 1, 1964

By K. E. Haque

"This paper is a brief overview of the role of oxygen in cyanide leaching of gold feeds (e.g. ore, concentrate). As the majority of gold occurs in the elemental state (Au °), its oxidation is of vital importance for dissolution in the cyanide lixiviant. The cyanidetion at high pH is favourable for the oxidation of Au° with a mild oxidant such as air or oxygen. Beside oxidation of gold, deleterious effects of soluble sulphides, arsenates, antimonates on cyanidation of gold can be alleviated by preaerating the leach slurry with air or oxygen (i.e. preaeration process).If gold is refractory due to its occlusion in sulphides, silicates, tellurides, etc. then gold liberation is possible by roasting in the presence of oxygen or by leaching under oxygen pressure. The data in the recent literature indicate that reactive oxygen supplied by H202, Na202, Ca02 or 03 during cyanidation can accelerate considerably gold oxidation-cyanidation and yield high gold recovery in much shorter leach time. The information compiled in this review leads to the conclusion that oxygen plays a vital role in the dissolution of gold in cyanide lixiviant."

Jan 1, 1992

By Jerry Ran

When multiple levels are mined in open stope mining with delayed backfill, mining underneath fill is inevitable to achieve higher rate of recovery if no sill pillars are left for the purpose of fill separation or partial ground support. This is particularly true when the orebody has low reserves per unit vertical distance. Instability of the exposed fill back causes stope dilution, production delay and possible equipment damage and consequently increases the mining cost. Previous studies have concentrated on fill mat stability in cut-and-fill and stability of fill walls in open stope mining. Workers are exposed to the fill back in cut-and-fill and therefore smaller open spans are normally adopted and the fill mat is reinforced. In open stope mining openings with large spans are designed, workers are not exposed to the fill back and its stability has to be maintained by fill of sufficient strength. However, the required fill strength is normally determined by considering different modes of fill wall failure. The fill back stability is usually not analyzed in the fill design process. The lack of analysis on fill back stability for open stope mining is mainly due to difficulties in relating the fill properties to the fill and stope geometry. In this paper a simplified wedge model is adopted to analyze stability of the exposed fill back in open stope mining with consolidated backfill. The proposed method calculates the factor of safety of the fill back against shear failure under known fill and stope geometry and fill strength parameters in order to assess the fill back stability. It can also be used to determine the required fill strength with known fill and stope geometry. The proposed approach is indirectly validated by mining experience and observations at two operating mines. In addition there are many factors affecting the fill quality and stope configurations in an operating mine. These factors have to be considered in the analysis of fill back stability. This situation is highlighted by presenting an actual mining case where the fill back failed due to factors commonly encountered in mining operations.

May 1, 2003

By B. D. H. Knights, N. B. du Preez

The recovery of the economy of the Democratic Republic of Congo has allowed for the rapid increase in production of copper from this region, while the increased price of cobalt continues to support the recovery of that country’s economy. This has enabled the modernization of the process technology used, particularly the change from direct electrowinning of copper to solvent extraction-electrowinning. With this change has come a variety of technical challenges in optimizing the recovery of cobalt from these sources. In this paper, we discuss aspects of the flowsheets for the production of cobalt from the ores of the DRC and Zambia, highlighting the technological improvements that have been made. Following this description of the practice, we assess the challenges of further improving the recovery and purity of cobalt from these sources. INTRODUCTION The African Copperbelt (Figure 1) is by far the biggest producer and holds the greatest reserves of cobalt (Sheed, 2015). However, the ores of this great mining region are extracted primarily for their copper content, and cobalt is a by-product. The ratio of copper-to-cobalt is between 6 and 20 to 1, with the ores from the DRC richer in cobalt than those from Zambia. The overall supply of cobalt, shown in Figure 2, is increasing due to an increase in demand for its use as a battery material. Cobalt is used in superalloys, hard metals, pigments, catalysts magnets, tyre adhesives, lithium-ion rechargeable batteries, and wear-resistant coatings, amongst others. Although these generic categories persist, Figure 3 shows how the relative usage of cobalt is changing due to the uptake of electric vehicles in China and Europe. Cobalt is a key element in lithium-ion batteries, and because it is widely anticipated that electric vehicles will be legislatively encouraged, it is anticipated that the demand for cobalt will rise. This anticipated increase in demand resulted in an increase in the price for cobalt, to which suppliers responded over-eagerly, and the price has dropped dramatically in the first few months of 2019, as shown in Figure 4. However, there is a clear cycle of price peaks in cobalt’s history.

Jan 1, 2019

By J. E. Dutrizac

"The end of an era in zinc metallurgy took place on July 31, 1976 when the horizontal retort furnaces of the National Zinc Company in Bartlesville, Oklahoma were permanently shut down (1) . For more than a century, horizontal retorting had been the most common method of producing zinc in the United States; it was a thriving industry in many parts of that country, especially in the natural gas belts of Oklahoma and Texas. With the Bartlesville closure, yet another metallurgical process has become an object of historical interest for North American metallurgists. Although shrouded in controversy, the origins of zinc metallurgy seem to date back at least 2000 years. Pyrometallurgical methods with carbon reductants are capable of producing zinc from oxidic zinc ores, but only above the boiling point of the metal. Although slow cooling results in re-oxidation of the zinc vapour by air or carbon monoxide, quenching yields liquid zinc; some form of rapid cooling, either accidental or intentional, was likely used by ancient metallurgists to liquify the metal. Zinc metal found in Athenian objects of the Roman era was likely of accidental origin. The Romans employed brass extensively for coins and ornaments(2) , and this was intentionally produced by the calamine process whereby oxidic zinc ores were added to molten copper under strongly reducing conditions. Zinc appears to have been known in China and India as early as 1000-1300 A.D., and was probably smelted commercially in those countries from the 14th century. Although the early metallurgical procedures were probably inefficient, they were able to produce zinc metal in significant amounts. The large heaps of zinc residues with clay retorts bear testimony to an early smelting industry of impressive magnitude. It is estimated that the heaps at Zawar, India alone represent the extraction of 100 000 tons of metallic zinc(2) In the 1730s the smelting of oxidic zinc ores was developed in England using a vertical retort method. In 1788 a British patent was granted for making zinc from zinc blends (ZnS) by roasting the ore in a coalfired reverberatory furnace, mixing the calcine with charcoal and smelting the mixture with suitable zinc condensation. The English process was very energy intensive, however, and early in the 19th century the Belgians developed a horizontal retort process for the reductiondistillation of zinc that was more fuel efficient. This technique was gradually developed into what came to be known as the Belgian process, the forerunner of the ""modern"" horizontal retort furnace."

Jan 1, 1999

By A. Uribe-Salas, J. A. Finch, B. J. Huls

Froth depth or interface level is an important control variable in column flotation which can influence both grade and recovery. A common method of locating the level is based on sensing the hydrostatic pressure at one or more points along the column. The level indicated can be in considerable error, largely because of variations in froth and collection zone bulk densities. A portable conductivity probe has been developed to detect the position of the interface from conductance measurements across the interface. The location of the interface corresponds to the position where a large change in conductance is observed, which is primarily a consequence of the difference in gas holdup between the collection and froth zone. This probe detects the position of the interface to an accuracy of ± 5 cm. The probe can be used while the column is in operation, which allows for on-line recalibration of the level detection system. Results obtained in its application in a pilot-scale column (0.91 m in diameter) are described.

Jan 1, 1990

By A. Ignatieff

"A practical picture of the effects of stress and of the structural environment in an extraction area in a bedded deposit is described, and the main factors of ground control where principles of rock mechanics can be applied are discussed. Reference is made to early work in Europe, where systematic rock mechanics studies started in coal mines, as well as to the early work in the Canadian coal mines.During the past two decades, considerable theoretical and experimental knowledge, pursued both in the laboratory and in the field, has accumulated throughout the world, but the state of the science still does not permit application of substantiated theory such as is found in the design of above-ground structures, largely because of the complexity of the rocks. The mining engineer, as oppm1ed to the civil engineer, is constantly faced by exposures of new ground that is often subject to unpredictable discontinuities. However, the rationale already developed by rock mechanics principles and experimentation provides concepts and information that may be useful in selecting mining layouts. These concepts and existing measuring techniques can also assist ground control as mining progresses.Many of the bedded deposits, much as coals and evaporites, have pronounced deformation properties, and there are limitations in making stress measurements within short distances of mine openings or extraction areas. On the other hand, the measurement of movement of the hanging wall (roof) and footwall (floor) of roadways and extraction faces, as well as the sides of pillars, provides a most useful tool in assessing ground stability.This paper is to be regarded as a brief progress report with particular reference to Canadian applications of rock mechanics to bedded deposits."

Jan 1, 1968

By B. M. Das, F. Claridge, V. K. Garga

Coal, as well as a large part of other minerals in Canada, is produced by surface mining methods. This has resulted in short and long-term accumulation of waste rock in dumps. Two main problems arise from the flow of water through these dumps: stability of dumps and the impact on stream flows. In recent years, a number of mines have started placing waste rock in valleys for general disposal or far constructing mine access road ways. All these have created challenges in the following areas: effective design of dumps and flow-through dams; stability monitoring of the structures; environmental impacts downstream by way of increased amount of fines in suspension, sedimentation, and toxic substances; and long-term status of flow and flood. Similar situations also exist in many civil engineering structures. This paper discusses the status of rock drains and the immediate and future research needs.

Jan 1, 1990

By MacKenzie Dickson

"INTRODUCTIONGold is found in many natural states, native nuggets, loose grain in river sands, veins in rock, as well as associated with sulphides, oxides, etc., disseminated more or less minutely.Its high value in recent years has spawned new technologies to win values from sources once considered too lean for commercial recovery. Cyanide leaching from fine milled ore or tailings, from upstream recovery operations, coupled with adsorption onto relatively coarse granules of activated carbon, concentrate the gold enough to be converted to bullion by time-honoured methods.The carbon granules are fragile. Size degradation in handling must be minimized not only to prevent loss of gold on fine fragments of carbon that could pass with the barren tailings, but to maintain adsorption efficiency. Besides, the granulated carbon itself is costly. Circular Vibroscreens are winning acceptance for dewatering carbon granules thanks to their gentle yet effective performance in gold recovery systems around the world. The system at Equity Silver is illustrative.BackgroundEquity Silver Mines Ltd., Houston, British Columbia, first began production in September 1980. In 1984, a feasibility study showed that additional gold and silver could be economically recovered through cyanide leaching of the flotation tailing.Although the carbon-in-pulp (ClP) or carbon-in-leach (CIL) process is commonly used for extracting precious metals from slurries, the use of circular vibrating screens, and Vibroscreens in particular, for the carbon circuit is an innovation that cuts costs.Rectangular vibrating screens have been the conventional separation mechanism of choice across North America. In contrast, the use of Vibroscreens has been proven to be less costly for the initial purchase and installation. Also, these circular vibrating screens require less power and less space. A description of Equity Silver Mines' process shows how these screens have been successfully integrated into the system."

Jan 1, 1989

By G. C. Weatherly, L Beitelman, M Gray, M. W. Bates, R Hadden

"A program of evaluation of in-mould electromagnetic stirring on the product of a straight-mould, billet continuous casting machine has been carried out. The effects on macrostructure, surface and internal quality, chemistry segregation and mechanical properties on carbon, low-alloy and resulphurized, free-machining steel billets and rolled bars are discussed. Operational aspects as a result of in-mould stirring are highlightedIntroductionA development program on electromagnetic stirring (EMS) in the mould of a continuous caster was started by Ferrco Engineering Limited in 1979, with the first experimental device being developed and installed at Lake Ontario Steel Company. As a result of these initial trials, new designs of in-mould EMS systems have been developed and are currently being used in continuous casters in North America and Europe. The rapid progress which has been made is in large measure due to the fruitful cooperation which has existed between the various parties, including Ferrco, the EMS equipment manufacturer, several operating plants and the University of Toronto.A brief review of some of the basic ' principles of electromagnetic stirring action on solidifying metal, and the landmarks of this process development, will explain the philosophy of this cooperation.From casting practice, it is well known that an equiaxed dendritic structure provides better' material properties than a columnar dendritic structure. Homogeneity of the equiaxed structure leads to better control of material properties, such as strength and ductility. Therefore, many efforts are being made to obtain this structure in continuous casting.The extent of the equiaxed zone is determined to a large degree by convective flow in the liquid. Fluid flow can fragment dendrites in the columnar zone, which then act as nuclei for grains in the equiaxed zone farther down the sump. This process is referred to as dendrite or grain multiplication."

Jan 1, 1982

By Christopher Boys

"Many water inflows in Saskatchewan potash mines are linked to salt anomalies. Potash ore and three anomalies in the PCS Cory potash mine in the Patience Lake Member of the Prairie Evaporite Formation were studied to understand the processes involved in their formation. Another goal was to find geological indicators of the proximity of anomalies. A geological model that relates the potash to the salt anomalies has been developed.Up to five post-burial facies may be recognized. These range from carbonate-mud collapse breccias to bedded sylvinite, and probably result from post-burial leaching. In this model, the same fluids that caused widespread recrystallization and possibly enrichment of the potash salts, started by dissolving huge cavities in the evaporites. The effects of the leaching were highly variable, indicated by selectively preserved delicate laminae and chevron textures, to deformed and totally dissolved salt beds. In at least two major events, Late Devonian and Cretaceous, collapse structures may have acted as conduits for overlying formation waters to cause pervasive leaching and recrystallization of the Prairie Evaporite Formation.Geological indicators of the proximity of an anomaly may include: a change in insoluble seam color from greenish-gray to mottled brown and greenish-gray, unusual local increases in ore grade, large patches (e.g., >200 cm2) of sylvite-poor potash crosscutting units near the top of the ore wne, and drops in topography > 10 m of the marker seams. Anhydrite was more common in an anomaly than in ore. The local abundance of anhydrite in ore may indicate the proximity of some salt anomalies. Once an anomaly has been encountered, indicators of a major collapse feature may include: stretched clay seams, folded beds, small collapse features (1 m to 20 m), numerous washouts, or split clay seams with injected salt. Any number, or none, of these indicators may be found close to a major collapse feature."

Jan 1, 1993

By J. F. Henderson

"IntroductionTHE National Advisory Committee on Research in the Geological Sciences was set up by the Privy Council of Canada in 1949. It was set up because you, the Geology Division of the Canadian Institute of Mining and Metallurgy, asked that it be set up. The Committee is, therefore, to a consider-able degree, your offspring. In the role of good parents you, of the Geological Division of the C.I.M., should be interested in the progress of your progeny. How is the Committee organized? What has it recommended? What has it accomplished? On behalf of the National Advisory Committee, that is what I want to tell you about this afternoon.HistoryYou will remember that, in 1946, the Geology Division of the C.I.M. set up a Committee on Geological Research. This Committee, under the Chairmanship of Dr. J. E. HAWLEY, found ""that there is no national organization interested in surveying, co-ordinating, and implementing with financial help, fundamental and much needed geological research. Accordingly, the first and most necessary step to put the geological sciences in Canada on a proper footing .is the recommendation that a National Advisory Committee on Research in the Geological Sciences be formed"" (l).This recommendation was endorsed •by the President and Council of the C.I.M. in 1947 and submitted to the Minister of Mines and Resources."

Jan 1, 1952

By L. Janku, G. Hancox, M. Villenueve, C. Massey

Wellington lies in a seismically active area 150 km from a subduction zone and in the vicinity of several active faults, which poses a risk to its infrastructure and inhabitants. One of these major faults, the Wellington Fault, runs through the centre of the city and across several lifelines, including the natural gas pipeline and the freshwater pipeline. The first settlement in the area was severely damaged in 1848, soon after its establishment, by an earthquake of approximate magnitude Mw 7.4 - 7.5 (Grapes, Little, & Downes, 1998). In 1855, another earthquake of magnitude Mw 8.2 generated by a nearby fault uplifted the eastern part of the current Wellington area and caused several landslides in the surrounding hills (Grapes & Downes, 1997). The Central Business District lies in the area of a sedimentary basin and partly on reclaimed land. Many residential areas, as well as some vital infrastructure, however, lie on or along the slopes in the surrounding hills. The bedrock in the area comprises predominantly the Torlesse greywacke of Permian – Late Triassic age. The greywacke is tilted to a steep angle, intensively faulted and fractured (Cook, 2001). Even though several studies in the past assessed the seismic risk in the area (e.g. Brabhaharan, Hancox, Perrin, & Dellow, 1994), the studies either focussed solely on the area of the sedimentary basin or based their assessment of the hilly terrain purely on slope morphology (slope angle). Previous studies have shown that slope shape and contrasting materials in the slope can amplify earthquake ground motions, such factors are typically called site effects (e.g. Geli, Bard, & Jullien, 1988). Any attempt to systematically quantify the site effects and consequent seismic response of the slopes and use it to predict the consequences of the next large-magnitude earthquake, has not yet been carried out. In this extended abstract we outline the methodology of a PhD research project, focussed on investigating the site effects on the slopes around Wellington and on creating representative numerical models of ‘characteristic’ Wellington slopes and materials. This extended abstract presents the methodology adopted for the assessment using the Te Ahumairangi Hill site as an example.

Jan 1, 2015

By E. Topuz, C. Duan

"INTRODUCTIONOperations research (OR) applications have experienced a substantial growth within the mining industry during the last three decades. The purpose of this paper is to present a summary of the results of a comprehensive survey of the application of various OR techniques to the major mining activities. It is hoped. through this sur vey , that the most widely used OR approaches, the important areas of application, and future trends have been identified.This survey included more than 500 articles published in this field in English since the late 1950s. Most of the relevant literature was found in mining publications, but, in terms of quality and originality, important applications were also found in literature not related to the mining industry. The sources constituted periodicals, proceedings research reports, and a few books. A listing of selected publications from which three or more articles reviewed in this survey appear is given at the end. Operations Research MethodologiesOperations research is concerned with optimal decision making in, and modeling of, deterministic and probabilistic systems that originate in real-life situation s. One basic feature of the OR methodologies is the attempt to optimize certain design parameters, subject to a set of constraints. This distinction has been employed in the survey as a guideline for selection of the techniques covered under the title "" OR methodologies"". The methodologies thus encountered in the literature are listed below. In a few cases, simulation has not been considered because it is not an optimization method per se."

Jan 1, 1989

By Dart Wantland

"AbstractThe scope of geophysics in civil engineering and the nature of exploration geophysics are briefly discussed. Engineering problems amenable to geophysical attack are illustrated by specific examples. The various methods available, accuracy of results, and costs are treated. The possibilities of new uses of geophysical techniques are pointed out.IntroductionTHE SCOPE of geophysics in engineering is different than in oil or mining exploration. In civil engineering, geophysics solves specific problems; as for example, what is the depth to bed-rock along the axis of a proposed dam? The area to be surveyed is of limited extent, and the subsurface information .sought is relatively near the surface. The engineering geophysicist is not called upon to investigate geological basins or extensive mineralized areas or to probe for data to thousands of feet in depth. The geophysical tools employed in the three fields are, however, quite similar; the differences are mainly in the objectives.The Natural Geophysical ExplorationThe terms geophysics and geophysical exploration have been used heretofore and will .be employed in what follows. The question is, therefore, What is geophysical exploration?Geophysical exploration is a line of field work where measurements are made at the ground surface with special instruments to get geological subsurface information. Briefly stated, geophysics is a form of exploration that supplements geological work. It is a blend of physics and geology since physical measurements are made •at the surface of the ground that can be interpreted in terms of subsurface conditions."

Jan 1, 1953

By Y. Luo

The rock breakage process in drilling is a main source of noise in roof bolting operations, especially when hard rocks are encountered. Proper control of drilling operation can provide an opportunity to improve energy efficiency of drilling and to reduce noise and heat generated from bit-rock friction. Drilling tests have been conducted in laboratory settings to confirm this noise-reduction strategy. Preliminary results show that the drilling parameters, penetration and rotational rates can be controlled to achieve in a desirable range in drilling medium hard rock. Based on the theoretical and experimental studies, rational drilling control strategy is developed for noise control while maintaining a safe and productive roof bolting operation. Applying this strategy in underground roof bolting operation, the noise exposure of roof bolter operators will be significantly reduced.

Aug 1, 2013

By M. J. Sapko, R. W. Watson, E. S. Weiss

The relative incerdivity of several blasting agents was evaluated in the Bureau's Bruceton Experimental Mine (BEM) . The minimum charge weights resulting in the ignition of predispersed oil shale dust clouds were measured for each of the explosives. A 400 g unstennned charge of ANFO (ammonium nitrate-fuel oil) was sufficient to initiate an oil shale dust explosion, whereas a 1000 g unstenuned charge of an emulsion blend did not ignite the dust even with the addition of 4% methane gas. Several stenuning materials were evaluated in the BEM for their effectiveness in preventing the ignition of near stoichiometric methane-air mixtures. Water stenuning was superior to all other inhibitors tested against methane. Explosibility testing of fine sulfide ore dust in a 20 L chamber and in the BEM show that the dust is capable of propagating an explosion given nominal concentrations of 700 to 800 g/m3. Results are encouraging and irrlicate that there is merit in pursuing explosive composition as a means of reducing ignition probability of oil shale and sulfide dust clouds generated during nonnal blasting operations. The proper selection of explosives and stenuning materials should significantly reduce the probability of secondacy dust explosions in oil shale and sulfide ore mining.

May 11, 1988

By R. Heikkilä

In this paper the utilisation of building information models (BIM) and construction automation on building sites is discussed. A lot of research has been carried out to develop new applications for using BIM to assist construction site planning, different operations and logistics. The methods of production control and management on site utilize BIM together with machine control and navigation systems. In Finland machine control systems and the automation of construction equipment is widely used in infrastructure construction. Recently similar methods have been introduced also in building construction. This paper describes some latest Finnish examples where BIM-software is used for the planning, execution and control of building construction operations. University of Oulu has studied methods and technologies to capitalize BIM-models. The research has been mainly in infrastructure construction but the activities have recently been extended to building construction. In this paper a BIM-based tower crane operation and control system is discussed as a case study. The aim of this study was to highlight the potential areas were automation can increase the crane productivity and improve site operations and logistics. The construction site managers and tower crane operators interviewed in this study were experienced in using BIM-models on site.

Aug 1, 2013

By T. Eger

Load Haul Dump vehicles (LHD) are extensively used in underground mining however equipment design and operating conditions contribute to restricted operator?s visibility. The inability to clearly see people, objects or hazards around the machine has contributed to a number of accidents including fatal injuries. In order to identify vehicle design characteristics resulting in restricted and blocked sightlines visibility assessments are traditionally completed in the field. However, field methods are unable to evaluate visibility under dynamic operating conditions and are limited in their ability to provide feedback on the impact of various operator characteristics such as sitting height, for example. Results of this research show computer simulation and virtual reality can be successfully used to evaluate visibility during the operation of LHD vehicles. In order to benefit from virtual reality applications the work environment, LHD vehicle and human posture need to be represented as accurately as possible. A computer simulation program with ergonomic ana lysis features, Classic JACK 3.1, was successfully used. Threedimensional CAD models of LHD vehicles were developed from manufacturer specifications and pictur es taken from LHD vehicles currently in use. The LHD models were imported into the JACK environment, a digital human was positioned in the cab of the LHD vehicle and the vehicle and human where driven over a typical mine route. Real-time feedback in the JACK program was used to identify what the operator could see under different operating conditions. Machine characteristics and operating scenarios resulting in impaired visibility were successfully identified with this method. The JACK program can also provide real-time feedback on the human?s joint forces and torques, strength requirements, postural comfort, and metabolic energy expenditure. As a result, this method could be used to successfully evaluate musculoskeletal injury risk factors along with system design recommendations to improve workplace safety and productivity in any setting. The LHD VRML files imported into JACK have also been combined with environment files into other VR software packages (e.g. Maverik) to view in a VRL facility, managed by MIRARCO at Laurentian University. The VR models using these packages can be viewed in stereo to provide better appreciation of spatial visibility issues.

May 1, 2003