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By J. Navoyski, B. Macdonald, W. J. Helfrich, J. L. Bellanca, B. Demich

DISCLAIMER The findings and conclusions in this paper are those of the authors and do not necessarily represent the official position of the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention. Mention of company names or products does not constitute endorsement by NIOSH. ABSTRACT The pervasiveness of high-fidelity video games raises expectations of quality, detail, and lighting in virtual reality (VR) applications. However, high-quality models of mining equipment and environments are often not readily available, and developers may not be familiar with the latest techniques, such as physically based rendering (PBR). Because a consistent aesthetic is critical for maintaining immersion and controlling visual stimuli in research as well as in training, researchers at the National Institute for Occupational Safety and Health (NIOSH) created an asset development workflow. This paper details this workflow, including precision modeling and PBR techniques as well as a rigorous review process. It also describes lessons learned in the creation of photorealistic VR assets. BACKGROUND Virtual reality (VR) describes the simulated experience generated by an assemblage of hardware and software that are used to immerse the user. Over many years VR developers targeted the development of virtual environments (VE) toward various purposes: entertainment, the treatment of phobias [1], rehabilitation [2], and training [3]. A large part of the VE development includes digital assets, where digital assets refer to the non-programmed elements including 3D models, audio, and user interface. Because vision provides nearly 10Mbps of data [4] and accounts for the majority of all sensory input combined [5], a focused effort on asset appearance in VEs is warranted. Furthermore, research has shown that higher-resolution imagery increases search performance and training transfer, necessitating high-fidelity assets [6, 7]. In addition to being visually appealing, it is important that the assets and environment are also dimensionally accurate and consistent in order to elicit appropriate responses from the end users as they interact with and among these items [8, 9]. Researchers at the National Institute for Occupational Safety and Health (NIOSH) have developed VEs and digital assets under several research projects over the course of the last two decades [10, 11, 12, 13]. This work has provided researchers with a strong knowledge base for digital asset development. However, the assets themselves have had limited reuse value. Due to the extended timeframes and limited scope of these projects, the previously developed assets are not consistent in visual quality and dimensional accuracy. Moving forward, researchers wanted to minimize future development time and use of resources as well as adopt new asset development tools and game engine technology. Therefore, the aim of this paper is to document a new asset development workflow including geometry, materials, UV layout, and shader implementation combined with review steps in order to produce high-fidelity simulation assets that are accurate with consistent characteristics, using repeatable methodologies that are well documented.

Jan 1, 2019

By J. R. Dyni

The lacustrine Green River Formation of Eocene age in the Green River Basin, southwest Wyoming, contains the world's large resource of natural sodium carbonate in bedded trona (Na2CO3? NaHCO3? 2H2O). In this study, 126 billion tons are estimated to be present in 22 beds, ranging from 4 to 36 feet in thickness. These 22 beds underlie areas of about 50 to more than 775 square miles at depths ranging from about 650 to more than 3,000 feet below the surface. The total resource of trona ore in the basin for which drilling information is available is estimated to be about 149 billion short tons. The undeveloped deeper trona beds in the southern part of the basin may be exploitable by solution mining. Additional unevaluated sodium carbonate resources are present in disseminated shortite in strata interbedded with the trona and in shallow sodium carbonate brines in the northeast part of the basin.

Jan 1, 1995

By Ditend Tesh, Mallikarjun Pillalamarry, Nikowa Namate, Harmony K. Musiyarira

Many reports have been written about the issues surrounding small scale miners’ challenges in Namibia; yet little has been done to address these challenges. There has been a fragmented approach to address these challenges. Various government arms and donor organizations have utilized piece meal methods in the past in trying to make improvements on the productivities across the sector, but with no meaningful success. This has led to the design and implementation of inappropriate technologies and support services for the sector. The structures of many of the semi-precious stones mining businesses are informal, with very little royalties received by the government. Miners often work informally or illegally and they fear government interference and they distrust outsiders, resulting in them withholding production information. The presence of small scale miners is quite often associated with major challenges, including poor safety and environmental management standards, the spread of communicable diseases and poor working conditions. The majority of the miners employ uncontrolled extraction techniques which damage the crystals and mineral specimens, resulting in intermediate and final products of low quality along with high wastage at the extraction stage. The vision of the Namibian government is to expand the range and value of semi-precious stones and jewelry products processed within Namibia, while curbing illicit flows of raw stones. This will simultaneously secure maximum benefit for the country. This study investigated the interventions aimed at making the small scale mining sector in Namibia sustainable. A baseline study was conducted to analyze the current situation and characterize the industry, including a SWOT analysis. Information was collected through questionnaires, interviews, consultative meetings, field visits and workshops in order to profile the sector. The baseline study results were used in developing interventions for improving artisanal and small scale mining operations. The main challenges for the Namibian semi-precious sector were identified as: factual information about raw material resources and its beneficiation are insufficient or not available, lack of skills, lack of education and access to finances, rudimentary exploration and mining practices, trading and logistics that are not functioning effectively and inadequate sector governance. One key finding of this study was that Namibia is not benefiting through value addition due partly to illicit flows of the uncut stones and to the fact that lapidary is not much pronounced to a greater extent. The following strategic interventions were identified as key in ensuring the sustainability of the small mining sector in Namibia: conducting geological assessment to identify new deposits and quantify the existing ones, improving exploration and mining practices, investing in education and training, creating an enabling environment and improving the sector governance and strengthening the sector organization and supporting the infrastructure.

Jan 1, 2017

By C. J. Lewis

Commercial lime plants in the United States and Canada are depicted in Figure 1. The sources of lime available to Nevada and bordering states are rather few. Chemstar Lime has plants at Apex, Nevada and Nelsen, Arizona. Continental Lime, Inc. has plants at Tacoma, Washington, Townsend, Montana and Delta, Utah. However, Continental Lime has a new rotary kiln installation underway near Wendover, Nevada. This plant is scheduled to come on stream in the fall of 1989.

Jan 1, 1989

By J. A. Herbst, K. N. Han, P. B. Queneau, S. W. Asihene

As hydrometallurgy matures as a technology, more of its existing process knowledge will continue to be summarized in the form of detailed mathematical models. This development is happening at a time when major improvements in computer hardware have reduced the cost of computing. The opportunity then exists, through the solution of these process models, to design, control, and optimize hydrometallurgical plants on the basis of the physics and chemistry of its processes and less on empiricism. In this paper, a review of the current capabilities of sensors and phenomenological models for selected hydrometallurgical processes is presented. Future trends, in terms of the control and optimization of hydrometallurgical plants, are then explored. The possibility of simultaneously optimizing plant design and associated process control system performance is discussed.

Jan 1, 1993

By F. Habashi

Japan was a closed society until 1853 when it was forced to open to the West. Mining, metallurgical, and geological education started there around 1861 when a graduate from Yale University in USA went to Japan to organize the first School of Mines. This was followed by other metallurgists from Great Britain, France, and Germany and thousands from other disciplines. The present report is a summary of the writer's first contact with Japanese metallurgists and his visits to a number of universities and research institutions in the past years.

Jan 1, 2012

The fundamental objective of mine plans are usually to maximize the mine profit by extracting ore at the lowest possible cost over the mine life while some technical constraints are satisfied. Since the costs associated with the operation of trucks and shovels as resources are significant, determining the optimum number and allocation of these resources is an essential issue. This paper presents a Mixed Integer Linear Programming (MILP) model to determine the optimum number of shovels and trucks required to meet the short-term plan?s goals. Also, the model takes into account the allocation of trucks and shovels to mining faces. This model minimizes operational costs, while attempting to meet the production demand and to satisfy technological constraints. This paper also analyzes the operations of trucks and shovels in an open pit mine using ARENA simulation software.

Jan 1, 2012

By J. W. Merks

Applied statistics provides scores of powerful tests and techniques that are widely used and abused in science and engineering. The variance is the basic measure for variability, precision and risk. The formulas for the variances of the arithmetic mean and the weighted average are derived from the variance of a general function, as defined in probability theory. The requirement of functional or mathematical independence in probability theory translates into the concept of degrees of freedom in applied statistics. Geostatistics is the only variant of statistics in which functional dependence and degrees of freedom are irrelevant. This paper examines whether such basic elements of probability and statistics can be ignored with impunity.

Jan 1, 1998

By D. Jacobson

There are many different machine design parameters and variables that affect the production of cone crushers in a mineral processing plant. One of these variables is the speed at which the cone gyrates. In June 2012, pilot tests were conducted to determine the production and operating conditions over a wide spectrum of speeds. mining operations will have variations in the ore characteristics and feed rates that result in non optimal use of the crushing energy and inconsistent process control. This study documents the measured variation in production and energy efficiency with two operating modes. Overall, the results match the theory, and the capacity and power fluctuated by 25% and 17%, respectively, when operated at full capacity, with an overall trend of slightly coarser discharge size distribution as the speed decreased. Using a fixed feed rate, the crushers had 4-14% higher production when operating at the optimal speed. Secondary analysis showed that the power draw consistency and magnitude of power spikes could also be improved by optimizing the cone speed. Varying the speed of the crusher can be used to tune the crusher during commissioning, adapt to changing ore conditions over long periods of time or be used as a dynamic input into an advanced control system. each action above would serve to make the crusher(s) more productive, more energy efficient, impove process control and would also have mechanical benefits for the machine

Dec 1, 2013

By Danforth R. Hale

The pressure of military use of quartz resonators led to efforts to Grow high, grade quartz crystals in Germany and in Great Britain during 19)3-25, and was responsible for a series of U.S.A. Signal Corps contracts beginning in 1946 with the Clevite Corporation (as the former Brush Development Company), Bell Telephone Laboratories, Antich College, and others. The technique of growing crystals from the melt, such as KI, NaBr, was already commercially inuse Quartz could not be so grown, since its utility depends on the form stable below 573°C, and, even if it could be grown from an extraordinarily viscous melt, the higher form passing through this transition becomes twinned. Again, several crystals were being grown commercially from water solutions; quartz, however, is listed in the common literature as being insoluble in water. Fused quartz, or vitreous silica, was chosen as raw mater¬ial by the European experimenters because of its thermodynamically lesser stability than quartz, and various alkaline solutions were tried for the purpose of enhancing the solubility.

Jan 1, 1964

Research has determined that ground control interaction problems in mining over a previously mined seam occur primarily in the tension zone created at the edge of the subsidence trough, and in areas above lower seam remnant pillars. Based on empirical and analytical studies, planning options for improving conditions on the upper seam have been developed to optimize extraction while minimizing the negative effects of seam interactions. These options include prediction of potential upper seam damage, guidelines for minimizing inevitable negative interaction effects, and recommended opening and pillar sizes, shape, and orientations, as well as design and planning procedures.

Jan 1, 1988

By A. L. Slaughter

A mineral deposit has been discovered and explored sufficiently to establish the presence of ore in ?commercially marketable quantities," This is the point at which exploration ends and development begins, Of course, when the presence of commercially marketable quantities of ore are thought to be present the deposit had to be evaluated before this decision could be reached. If, on the other hand, it was thought that commercially marketable quantities of ore are not present, either more exploration has to be done or the project must be abandoned. It is this decision with which this paper is concerned, more particularly, the influencing factors behind this decision. The final question to be answered is: what profit can my company reasonably expect to make by developing this property and putting it into production? The answer must be expressed as a figure for final profit per ton, money which can be used to pay dividends or to build up cash reserves. Some acquisition cost has probably been paid and the exploration cost incurred at the time of decision, (abandonment or development). In addition to returning these acquisition and exploration costs, the deposit must pay development, mining, milling, capital expense of new plants and equipment, taxes, and various other related costs.

Jan 1, 1958

By Bruno A. Fichna

Longwall mining offers low cost potential for coal with high capital investment. As opposed to two shifts-per-day operation in most long- walls, Saarberg Mines in Germany increase utilization of capital by operating their longwalls around the clock. Differentiation between capital and operating costs, corrective maintenance versus preventive maintenance, improved roof conditions, and economical life of equipment was investigated. A surprisingly high degree of improvement was attained. Capital costs at Saarberg longwall coal mines have been reduced through a step-by-step research and trial program. This reduction was particularly influenced by the high performance pilot longwalls at the Ensdorf mine. The following presentation shows data and figures of those longwalls. End results were 40% reduction in capital costs, which could contribute favorably to investment decisions in the coal industry in a supply side economics environment.

Jan 1, 1982

By V. Kontogianni

The underground extraction of coal is associated with ground movements extending from the mining area to the ground surface, which result in bowls of ground subsidence, with amplitude exceeding the amount of several meters and occasionally with important tilt and curvature of ground surface. Such changes at both the underground environment and surface topography lead to destruction of buildings, failure of utilities and transportation networks, and occasionally formation of areas vulnerable to flooding, or even small pools. Based on geodetic surface measurements of ground elevation changes, various theories and empirical models relating surface subsidence with the geometry of underground voids formed have been proposed, and predictions of expected subsidence in the form of contours have been estimated. In this study a case study of planning of a new highway network through areas in which coal extraction was also planned is discussed. This work is partly funded by EU. The optimum solution selected was a modification of the initial highway planning, so that the road is increased in length and by-passes the richest coal-field, where maximum post-exploitation subsidence was predicted, and only crosses either minor coalfields, which are not to be exploited, or even margins of main coalfields, in which minor post-exploitation subsidence is expected.

Jan 1, 2006

By Akira Tsune, Shingo Sugimoto, Tadayuki Ishiyama, Nadao Saito, Masatsugu Okazaki

"The Deep Ocean Resources Development Co. Ltd. (DORD) of Japan signed a 15-years contract with the International Seabed Authority for exploration of polymetallic nodule in a 75,000 km2 area, consisting of West and East Areas in the Clarion and Clipperton Fracture Zone in 2001. The exploration work is now concentrated in resource estimation of the first generation of mining area, the High Abundance Area.A detail survey of the Model Area, set in the High Abundance Area, was conducted using AUV (Autonomous Underwater Vehicle) equipped with MBES (Multi-Beam Echo Sounder), SSS (Side Scan Sonar), Sub-Bottom Profiler (SBP) and still camera. The seafloor topographic map based on 1 m grid data was produced in an area of approximately 80 km2 (Figure 1). Photographs, continuously covering the seafloor taken by AUV along two west-east trending traverse lines, together with detail seafloor topographic map produced from MBES give an excellent opportunity to observe distribution manner of pollymetalic nodule related to topographic features. This helps to understand more accurate resources estimation of a whole area of the High abundance Area. Furthermore, information of micro-topography gives ideas for conducting ore collecting operation and designing ore collector."

Sep 1, 2014

By D. W. Fuerstenau, S. Raghavan

This paper presents a brief summary of some of the thermodynamic aspects of flotation processes. Thermodynamic considerations that control interfacial and wetting behavior in mineral/water/air systems are discussed. Particular attention is given to the thermodynamics of collector adsorption.

Jan 1, 1976

By Paul F. Ziemkiewicz, Aaron Noble, Christopher R. Vass

The conventional rare earth element (REE) industry has historically sought to develop ore deposits where geologic processes have produced mineralized zones with commercially attractive REE concentrations. These deposits are extremely uncommon, particularly in the USA. Given the criticality of these materials and the need for sustainable domestic supply, the current research seeks to leverage other autogenous processes that lead to concentrated REE resources. One such process is the generation of acid mine drainage (AMD). AMD is very common in many coal mining districts and results from the exposure and oxidation of pyrite during mining. During the generation and migration of AMD, liberated sulfuric acid mobilizes several metal ions including REEs. Treatment of AMD is required under U.S.C §1251, the Clean Water Act, and often consists of neutralization, oxidation, and metal hydroxide precipitation. To investigate the deportment of REEs during this process, a field sampling campaign was undertaken, whereby the concentration of REEs in AMD and AMD precipitates was measured directly. In the nine sites evaluated in this study, the REE concentrations of the precipitates varied from 29 to 1286 ppm with an average of 517 ppm among the sampled sites. The individual elements were enriched compared with the associated bulk Northern Appalachian (NAPP) coal material by factors ranging from 3 to 15. Furthermore, the distribution of REEs in all precipitate samples favored the heavy REEs (HREEs) when compared with traditional REE ores. This research represents the first part of multi-part research endeavor to characterize, classify, and determine the practicality of refining REEs from AMD and its by-products.

By John Ralston, Rossen Sedev, Nicola Richards, Quinn Anthony, Geoffrey Reynolds

Derivatised 2,4-diketopyrimidine groups have been anchored to planar gold surfaces as self¬-assembled monolayers (SAMs) for chemical and photochemical studies. Three derivatives, 5-methyluracil (thymine), 5-trifluoromethyluracil and 5-nitrouracil, were chosen for the specific moiety present at position C-5, which can exert strong or weak inductive effects on the adjacent aromatic ring. The measured acidity constants decrease from 5-methyluracil to 5-nitrouracil as the inductive properties of the group at C-5 position increase. When grafted to the surface the acidity constants increase, albeit still adhering to the expected inductive trend. The functionality also exerts an influence on the surface wetting properties. Surface wettabilities indicate that the orientation of the pyrimidine groups at the surface occurs so that the C-5 position has a direct effect upon the surface chemistry. Upon dimerisation the surface contact angles increase signifi¬cantly. At pH 11 the contact angle changes reflect that the dimer has a higher pKa than the monomer. The monomer surface is deprotonated at this pH while the dimer surface is partially deprotonated, leading to changes in contact angle of up to 22 degrees. Large changes in contact angle were observed for 5-nitrouracil which were independent of surface charge and were appar¬ently due to conformational changes alone. Electrowetting of three fluoropolymer surfaces by electrolyte solutions was studied with the sessile drop method. The electrowetting curve (contact angle/potential) is analogous to the elec¬trocapillary curve (surface tension/potential) and may be described by a combination of the Young and Lippmann equations. We demonstrate that for some specific surfaces a systematic deviation occurs at positive potentials. This departure is attributed to double layer effects, namely the adsorption of hydroxide and halide anions. pH, ionic strength and polymer composi¬tion can all influence electrowetting behaviour.

Jan 1, 2003

By P. C. Schutte, A. J. Kielblock

INTRODUCTION Certain activities, such as emergency work and rescue operations, often have to be undertaken in environments where heat loads often exceed limits prescribed for routine work. This is particularly relevant to the South African mining industry where heat stress-induced fatalities are not uncommon during rescue operations. In this regard an excessively hot environment is defined as one where either the dry-bulb temperature exceeds 37,0°C or the wet-bulb temperature exceeds 32,5"C, and it is therefore not surprising that heat stroke mortality escalates rapidly when these limits are exceeded. A review of both local and international standards indicated that the available information on safe exposure times under abnormal heat stress conditions is very limited. Where available, such standards are aimed at the general population, including both sexes, irrespective of age and also the least heat tolerant worker, and not at a medically-screened, all-male population free of grossly heat intolerant individuals, as is the case in the South African mining industry. It is suggested that available norms and limits are too conservative for local application and, therefore, unrealistic. In view of the definite need to protect workers when exposed to abnormally high environmental temperatures, the present study was undertaken to establish a scientifically derived data base. applicable to local conditions, to determine safe exposure times: Any exposure limit, especially in an emergency situation, should be easy to administer, valid and reliable. These aspects, there- fore, form an integral part of this paper. FORMULATION OF HEAT STRESS LIMITS The formulation of heat stress limits was based on the criterion that a heat exposed individual should experience a negligible risk of developing dangerously elevated body temperatures. In order to provide a database for risk assessment, certain physiological responses of heat tolerant men were determined at various combinations of thermal conditions and work rate in a climatic chamber. These physiological responses were analysed statistically in order to predict safe survival and tolerance times as a function of thermal conditions and work rate. EXPERIMENTAL DESIGN A total of 202 randomly selected, medically fit mine workers volunteered for the study on the basis of informed consent. These men were considered to be inherently heat tolerant in as far as they had successfully completed a heat tolerance test (Anon., 1991) or the standard climatic room acclimatisation procedure used on many South African gold mines (Anon., 1989). The subjects were allocated randomly to 14 experimental groups and each group was exposed in a climatic room to one of

Jan 1, 1997

By H. H. Murray

Abstract. World reserves of bauxite are abundant. Domestic reserves are limited and as a consequence the United States must rely on foreign suppliers for over 90 percent of its bauxite. Nationalization of many bauxite mining operations, levying of higher taxes, increased production and transportation costs, and attempts to create a uniform market price combined to place the United States in a vulnerable position. Alumina from kaolin, alunite, anorthosite, and oil shale have-been-or are being evaluated. World bauxite reserves are increasing and attempts to establish a uniform price have failed; therefore, it may be many years before domestic non-bauxite sources of alumina can compete with imported foreign bauxite.

Jan 1, 1980