Search Documents

By Larry Schneider

Are you one of the thousands of hunters, fisherman, or hikers who purchased handheld GPS systems over the past several years and then been disappointed in their accuracy and performance. Or maybe you are one of the hundreds of blasters who have attempted to use GPS as a method for locating the exact position of their blast and measure distances from the blast to nearby structures. If so, you may have found that the accuracy of the handheld GPS systems left much to be desired. It may be time to get the units back out of storage and give them another try. As of midnight, May 1, 2000, the federal government has turned off the “error” built into the system known as “selective availability.” Here is a brief explanation of what that means in a question and answer format.

Jan 1, 2001

By W. N. Hoskins

This report covers the final results of a two-phase contract study conducted between July 1974 and October 1976. A comprehensive summary of the initial phase of the study is included. Phase I of the study involved the investigation and evaluation of all potential candidate underground systems for mining the deeper deposits of oil shale and associated minerals in the Piceance Creek basin of northwestern Colorado. Phase II called for the refinement and the detailed technical and economic analysis of the most promising system or systems, thus disclosed. Of the several systems initially investigated and evaluated, four Showed considerable merit for exploiting the deeper deposits: (1) chamber and pillar mining with spent shale backfill, (2) sublevel stoping with spent shale backfill, (3) sublevel stoping with full subsidence, and (4) block caving mining using LHD's. Final refinement and analysis of these four systems indicated their technical feasibility over at least part of the range of conditions expected in the deeper deposits. Their economic feasibility also was indicated under certain operating and market conditions. A variety of engineering, production, and cost information is provided on each of these systems.

Jan 1, 1976

By T G. Neville, G Terrey, J Burns

This paper explores recent industry training programs and lessons for supervisors. The Belbin Team Role model was used to increase participants’ awareness of behaviour and its application. The application of the Belbin model to underground, open cut mine and quarry supervisors is discussed.The key to team success may rest with the expertise and experience of its members, but increasingly effectiveness depends on how team members understand, acknowledge and support each other’s behavioural strengths. Discovering strengths is a challenge, both for their measurement and for the encouragement of team members to use the knowledge of themselves and others in the team. Using behavioural models provides a constructive approach and a language for supervisors as they build personal motivation and engagement.Prima facie, the mineral industry’s work may be too vigorous for teams and their managers could be more prone to use ‘solo’ or traditional management styles. Managers and supervisors must know when work allocated to a team is appropriate or where individual effort should be applauded and rewarded. For practical people with well-developed technical skills, improving the soft skills necessary for a supervisor requires some reflection and effort. The Belbin behavioural model can be an effective tool for recognising characteristics that can assist teams to be more productive.Experiencing the Belbin Team Role model as part of an industry qualification is important for supervisors studying to refine their team leadership skills. Data are available for participants to assess the nature of their teams and to confront the appropriateness of the behavioural mix for the work of the team and its individual members.So what are the next steps? All team development must have a place in the strategic thinking and plans of the enterprise. This needs a visible presence of senior managers and supervisors in managing a team culture with practical links to workplace priorities and professional development with continuous improvement.CITATION:Burns, J, Terrey, G and Neville, T G, 2016. Supervisors and teams at work, in Proceedings International Mine Management Conference, pp 125-138 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

The US Constitution provides for regulation by the states for protecting the public's safety, health, and welfare. Hence, in the eyes of the law of all states today, this is the sole justification for registration of professional engineers. Wyoming was the first state to register professional engineers in 1907, to correct abuses of incompetent or fraudulent practices in surveying and real estate. Public safety and health are most directly affected by civil, electrical, and mechanical engineering. Other branches of engineering have a profound effect on the public welfare, including investors, and safety and health of employees. No arguments, pro or con, are valid except in relation to the registration laws of various states. Code of Ethics Few would argue the desirability of requiring conformance with a code of ethics. A major problem lies in enforcing compliance, since protecting the public demands a high standard of competence, yet assessing competence gets confused with restraint of trade. Bidding engineering work on price competition can lead to pressure to cut corners on engineering quality, and was therefore discouraged by codes of ethics. The Supreme Court, in a suit against the National Society of Professional Engineers (NSPE), barred any engineering society from such bidding restriction. It has, however, upheld the right of states to impose codes of acceptable practice as part of registration laws. For example, Texas Canon I reads, "The engineer's paramount professional responsibility should be the safety, health, and welfare of the general public." Anything less makes the code practically meaningless, but there are potential conflicts of interest in many engineering organizations. How can conflicts be handled? Any corporation could improve its public image by adopting a policy that each employed PE should, without fear of recrimination, record in writing over his seal any problem or flaw in any design that comes to his attention. The policy should further require that his superior provide him a written reply pointing out that the "flaw" is accepted as requiring correction or as a calculated risk, or overruled as erroneous or as a difference of opinion. Errors in calculation of judgment are inevitable. Despite this, there are limits to how much time and money should be spent to eliminate them. It is difficult, however, to see any excuse for failure to conscientiously evaluate the opinion of a PE. This may be an impossible ideal, but how else can the profession or the industry have credibility? The National Council of Engineering Examiners (NCEE) has a code of ethics one presumably subscribes to by signing an application to write a Principles and Practices examination. However, NCEE has none of the power of enforcement that is available through state boards of registration. Registration Qualifications Qualifications are set by the laws of the states. In general, they require passage of an eight-hour examination in fundamentals, preferably at graduation, and, later, one in principles and practices. The examinations are compiled and distributed by NCEE. This system provides for a high degree of uniformity and reciprocity. States set the education and experience levels (typically four years after graduation) required by those desiring to write the principles and practices examination. Examinations The principles and practices examination calls for answering eight of 20 equal weight questions; one on engineering economics, 19 on engineering. Economics may enter into engineering questions, but only provided the question is not answerable by an economist without engineering training. In preparing examinations, NCEE strives to use questions that require some judgment and can be more effectively answered by someone with four years experience beyond college. The aim is to assess entry-level professional

Jan 2, 1984

By Huleatt M, Perkin D, McLeod I, Mock C, Pratt R, Gourlay A, Timoney E, Knight N, Ward J

Generally speaking, Australia's reserves of its more important minerals (in terms of export earnings) are adequate to sustain forecast rates of production to the year 2000. The rate of forecast production increases of these commodities (aluminium - whether as bauxite, alumina or metal, black coal, iron ore and ferro-alloy minerals, base metals, tin, uranium, and mineral sands) reflects a well- ordered and sustained growth phase of Australia's mineral industry.

Jan 1, 1981

The development of an onboard contaminant diagnostic monitor to continuously measure contaminant level in a mining machine was advanced to a prototype stage in this contract. Several concepts were investigated and it was found that a static spool type sensor was the most reliable and accurate. Laboratory and field tests showed that an instrument based on this concept is capable of measuring contaminant levels and/or size distribution, depending on the configuration of the sensor. Moreover, this instrument can function on emulsions or homogeneous fluids. Current laboratory equipment can operate on homogeneous fluids only.

Jan 1, 1983

By A. G. Sharkey

THE PURPOSE of this investigation was to develop methods for analyzing coal derivatives and products from the Fischer-Tropsch synthesis. As part of this investigation it was necessary to study the mass spectral characteristics of many classes of compounds. The mass spectra of alcohols, the trimethylsilyl ether derivatives of alcohols, acetal-type compounds, ketones, esters, and naphthenes were correlated with structure, and analytical methods were formulated. A method was devised to determine the ratio of branched to normal hydrocarbons up to CIS in the Fischer-Tropsch product. Low-ionizing-voltage mass spectrometry was combined with type-analyses to analyze tar acids and neutral oils from coal. The necessary sensitivity correlations at low-ionizing voltage were developed, particularly for phenolic compounds. Special analytical techniques were developed for the mass spectral analyses of specific compounds and compound types including (1) oxides of nitrogen, (2) hydrogen sulfide, (3) isomers of butenes and pentenes, and (4) hydrogen deuteride. An investigation was made of the effects of various hydrocarbons and oxygenated compounds on tungsten filaments in the mass spectrometer. The operating characteristics of rhenium filaments under similar conditions were studied. Several improved sample handling techniques were developed, including an automatic manometer and a self-filling micropipet. Studies were made of anomalous and negative peaks in the mass spectra of certain gases.

Jan 1, 1967

By Anand Kumar, Debasis Deb, V. N. S. Prasad. M, A. K. Mishra

Shield leg pressure data from all shields and shearer locationwith time stamp from a mechanized longwall face are monitored and recorded in a surface computer. These data contain random noise due to power failure, leakage of legs, bad sensor reading and other maintenance or geo-mechanical problems. An algorithm is developed to detect mining cycle parameters such as setting and final pressures and duration of the cycle from these data for the analysis of periodic roof weighting phenomena. The intensities and persistence of periodic roof weighting are the vital information to the mine management to take judicious decision on longwall operation. The paper presents details of the algorithm which identifies 96% of mining cycles from the noisy data belonging to consecutive 5 months or 410 m of face advancement. Based on this analysis, 2 types of periodic roof weighting phenomena are detected, namely, (i) normal type—having peak intensity of 75 to 90% of yield pressure, interval of occurrences of about 10 to 15 m with persistence of 3 to 4 m and (ii) severe type—peak intensity over 90% of yield pressure, interval of 25 to 40 m with persistence of over 10 m. It is envisaged that these phenomena have direct relationship with main roof thickness, its overhung length and material properties.

Nov 19, 2020

By Timothy J. Rohrbacher

This report presents a U.S. Bureau of Mines study that incorporates coal mining factors, coal recovery factors, and economic factors into the definition of an economically recoverable coal resource. The relationship between these factors to the Energy Information Administration's estimate of U.S. coal resources-the "Demonstrated Reserve Base"-is discussed. The Boltsfork 7 1/2-minute quadrangle in eastern Kentucky was selected as the study area. Results indicate that of the original 280.2 M tons of resource in the quadrangle, only 99.8 M tons (35.6%) is recoverable at a mining cost of $25 per ton or less.

Jan 1, 1994

By P. V. Chandramohan

"In ports, piled berths are designed and constructed for berthing of ships with a finite draught. Piles in a bridge foundation also have a large free stand above scoured level. The piles of these structures have to withstand large horizontal forces imparted by the impact of the approaching vessels or due to longitudinal and transverse action in a bridge. It is also imperative that these piles have to project out of the dredged / scoured bed. These piles are normally designed as slender compression members subjected to bending also. They are subjected to vertical load tests for assessing the soil resistance. Lateral load tests, as a rule, are also stipulated. IS and IRC codes stipulate a deflection criteria for lateral load test to arrive at the capacity. These tests are usually conducted on a working pile by jacking out two piles. At the time of the test, pile will be free headed. But in service, piles are fixed head. There is a large difference in deflections between a fixed head and a free headed pile. Besides, a free headed pile will be subjected to a much higher bending moment than the fixed head one. This will put the working test pile under risk of breaking during the test. The problem is analyzed with case studies. INTRODUCTION Vertical capacity of piles is assessed by static formulae. This formula is based on the soil properties obtained from random soil exploration and laboratory and in-situ testing. Since soil is not a homogeneous medium, properties can vary. The design parameters taken for computations may be different from the ones at the interface of the pile with the soil. The best way is to find out is by a load test. The code IRC:78-2014 has rightly stated that initial load test is part of the design process. This is true with the vertical load test. But there are certain problems with the purpose and inference of the lateral load test. In both the tests the criteria for acceptance is the quantum of movement of the point of application of the load. In the former, the movement is vertical and depends more on the compression of the soil than the compressive strain in concrete. But in the latter, this movement is partly on account of the flexural rigidity of the pile and partly due to the horizontal compressibility of the soil. The role of rigidity of the pile is more when compressibility of the soil is higher. Lateral load test is done by jacking one pile against another because it is difficult to get an independent horizontal reaction. Please see Fig.1 Photo."

Jan 1, 2015

Platiniferous horizons such as the Merensky Reef that are mined chiefly for their PGE contents constitute one end member of a continuum of Ni-Cu-PGE sulfide deposits; Ni-(Cu) sulfide deposits in which the PGE may or may not be by-products represent the other end of this continuum. Although it has long been thought that PGE-rich sulfides can only be developed by magma mixing in large magma chambers, new PGE data for the Bushveld Complex suggests an alternate model to account for origin of mineralization in the worldÆs most important Pt producer. Briefly, this model suggests that PGE-rich sulfides were initially deposited at depth below the Bushveld Complex as a result of interaction of a S-undersaturated mantle magma with S-rich crustal rocks. These PGE-rich sulfides were subsequently re-dissolved by a second magma, which introduced the PGE into the Bushveld Complex magma chamber, where the PGE-rich reefs were formed due to cooling of these magmas. If this model is correct, it means that large layered mafic/ultramafic intrusions are not a prerequisite for the formation of economic PGE-rich deposits. Exploration for Merensky Reef-type PGE deposits can be greatly facilitated by documenting variations in the background PGE contents of non-mineralized rocks collected on traverses across mafic/ultramafic intrusions; the mineralized horizons occur at cross-overs in ratios such as Pd/Cu, Pd/Se and Pd/S.

Jan 1, 2002

By S. L. Aaroe

"TYRETHANE PRODUCTSTyrethane® is the family brand name which has been adopted by The W. S. Tyler Company of Canada, Limited to identify its polyurethane products. Since we have been manufacturing Woven Wire Cloth for over one hundred years and have been the innovator for most of the product improvements and developments of that industry, it is only natural that our first and primary efforts involve the use of Tyrethane® as a screening medium. The product is ideal for application in the mining industry and other operations where the rate of wear on existing media is exceptionally high.In the event that you have already had some experience with polyurethane it should be poirted cut that there are many grades of the material. The polyurethane used in Tyrethane® Products will be compounded in a variety of chemistries and different heat treatments will be used to develop best mechanical properties to handle specific applications. However Tyrethane® will not be a ""cure all"" but when it is properly applied as a screening medium it will assist by lowering the unit cost for screened materials.Prior to an explanation of the advantages of Tyrethane® let's review the conventional screening media whose applications may be considered as good candidates for replacement by Tyrethane®.1.,Woven Wire Cloth.2.,Perforated metal screens.3.,Rubber faced perforated metal screens.4.,Perforated rubber screens.5.,Cast steel screen segments and weldiments.6.,Profile wire.In most cases a Tyrethane® section is designed for a one for one replacement of the material now being used. It is rarely necessary to modify the screening equipment to enable you to install the Tyrethane® Product although it may be desirable to take some steps to improve the service life of hold down components such as Clamping Strips or Tension Members. Those parts can be encapsulated in polyurethane if necessary.To fabricate the Tyrethane® section we have three basic building blocks. They are: (1) Small molded segments having square or slotted openings, (2) Reinforcing material and (3) the raw liquid polyurethane."

Jan 1, 1976

By G. E. Rennick

A siphon-type laboratory airlift well was designed and operated by the Bureau of Mines to study the concurrent flow of air and oil in small-diameter pipes. Glass flowstrings ranging from to 1 inch in diameter and from L4 to 64 feet in length were equipped with various-sized air-entry jets. Liquid holdup volumes were used to correlate vertical-flow data, and empirical equations for computing gas requirements were derived. The effect of flowstring length on flow efficiency, oil- and gas-production rates, and gas-oil ratios was relatively minor at all flowing pressures. Air-jet sizes and flowstring diameters, however, had a marked effect on flow efficiency and oil- and gas-production rates. The small air-jet sizes increased maximum flow efficiency and its associated flowing pressures but decreased oil- and gas-production rates. An increase in flowstring diameter increased maximum flow efficiency with its associated flowing pressure and also increased the production rates of oil and gas.

Jan 1, 1965

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 Leonardo Massone

The p-y method is one of the most popular methods in pile design and has been calibrated for various boundary conditions using numerical and experimental studies during recent years. Most studies on reinforced concrete (RC) piles have included the impact of flexural nonlinearity, (e.g. nonlinear moment?curvature relations) but not considered associated pile shear deformations when deriving p-y curves from field data. Common p-y curves may be better applicable for piles with flexure dominated failures (e.g. piles with free- head boundary conditions). For piles with fixed head boundaries (i.e. rotation restrained piles) shear deformations could be of significant influence. To study this problem, a coupled shear flexure interaction model for axial-bending-shear behavior coded in OpenSees was applied to a 0.61 m (2 ft) diameter flagpole and a 0.61m (2 ft) diameter fixed head pile specimen to investigate the possible influence of shear deformations to the overall pile responses. The surrounding soil was represented by p-y curves derived from prior large scale testing on piles with similar boundary conditions. Analysis results show that for flagpole piles, shear forces and shear deformations were insignificant. Considerable contributions of pile shear displacements and forces were observed for the fixed head pile, with shear displacements contributing up to 40% of the total pile displacement. Results suggest that nonlinear shear deformations for reinforced concrete piles should be considered for fixed-head or similar conditions, and that currently used p-y curves may underestimate the actual lateral pile displacement and possibly lead to unsafe design for the particular boundary condition.

Jan 1, 2012

How did you get into mining; were you from a mining town or mining family? Not at all. I grew up in northwest Kansas. I liked to hunt and fish, so I thought it would be fun to work for a company that made knives or guns. It seemed like metallurgical engineers would be something those companies could use, so I started in physical metallurgy. I got a summer job at the great Climax molybdenum mine near Leadville, CO shoveling muck onto conveyors. I was hooked. I loved everything about mining, so in the fall, I changed majors from physical metallurgy to mineral processing. For many years you actually discouraged young people from studying the mining disciplines. Could that be right? That’s true.

Jan 1, 2007

By D. K. Deardorff

The hafnium-vanadium phase diagram was constructed within an estimated accuracy of ± 10° C and ± 2 wt pct composition. Alloys for investigation were melted under an atmosphere of purified helium by nonconsumable tungsten-electrode arc melting on a water-cooled copper hearth. Melting points were determined by optical pyrometer, and the remaining phase relationships were investigated by metallography, thermal analysis, and X-ray diffraction. The existence of a face-centered cubic intermetallic compound HfV2 (a = 7.38 A) was confirmed. A eutectic reaction occurred at 20 wt pct vanadium and 1,395° C to yield HfV2 and 8 solid solution. HfV2 melted incongruently by a peritectic reaction at 1,480° C, and the 3 solid solution decomposed eutectoidally at 1,165° C and 6 wt pct vanadium to yield HfV2 and a solid solution. The eutectoid, the eutectic, and the peritectic isotherms extended from 1 to 36.3 wt pct vanadium, from 8 to 36.3 wt pct vanadium, and from 26 to 89.5 wt pct vanadium, respectively. Terminal solid solubilities of hafnium in vanadium at 1,300° C and of vanadium in hafnium at 1,100° C determined to be about 3 and 1 wt pct, respectively.

Jan 1, 1965

By R. Riding

Degussa Corporation's peroxide-assisted leaching (PAL) process was evaluated in the batch concentrate leach circuit at Hecla Mining Company's Republic Unit. The product leached in this batch circuit is a high grade gold-silver sulfide (predominately pyrite) flotation concentrate. The primary objectives of the test program were to determine the effects of dilute hydrogen peroxide addition on leaching kinetics, sodium cyanide consumption and precious metals recovery. The results of the testing demonstrated that using dilute hydrogen peroxide produced the following benefits: - 1. Batch leach time requirements decreased by 80%. - 2. Sodium cyanide consumption in concentrate leach reduced by 55%, which translated to an overall plant reduction of 20%. - 3. In the concentrate leach process, gold recovery was increased by 1 to 2%. Because of the excellent metallurgical results achieved with the use of dilute hydrogen peroxide, as well as an economic incentive, PAL has become standard practice in the concentrate leach circuit operation. A complete description of the Republic PAL plant evaluation and performance is provided in this paper. In addition, process chemistry considerations in regard to the role of hydrogen peroxide are discussed.

Jan 1, 1992

By L. A. Baker

The presence of goethite in a hematite ore has been shown to strongly affect the time of heating to the firing temperature. The investigation of spalling of single pellets and of packed beds has enabled free water and goethite spalling to be identified as separate phenomena. In addition, it has been shown that even for an 18 inch deep bed of green balls the free water and goethite drying periods can be considered separately. Based on this observation, a method of predicting production rate and hood temperature profile is presented. The method required knowledge of the ore goethite content, ore grind and the green pellet bulk density. Laboratory results were found to be in good agreement with actual plant practice and have led to improved process performance.

Jan 1, 1972

By R. C. Fernandes, F. L. Santos

Aluminum alloys in particular, have certain limitations when subjected to welding process. This is mainly present because aluminum alloys have high thermal conductivity, high contraction in solidification and high hydrogen solubility. Taking this into account, the FSW process has great potential for this application, since it is autogenous, held without metal melting and without the use of slags or shielding gases. From this concept, the aim of this study is to evaluate the joining of thin sheets of aluminum alloy 3105 H26 with 0.7 mm of thickness. To performing of the tests, some parameters were analyzed, such as: tool penetration in the sheets, attack angle, the type of welding tool and penetration control mode (position or force). The results indicated that the force control mode is most suitable for thin sheets, and the transient state at the beginning of welding was the most critical part to control the welding quality.

Jan 1, 2015