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This Bureau of Mines investigation addressed two primary issues of air velocity measurement in mines: the determination and use of correction factors, and the development of guidelines for the selection of a suitable site at which the measurements should be taken. Other facets of the investigation included a comparison of measurement methods and devices, and aircourse cross-sectional area measurement. The study consisted of theoretical, laboratory, and in-mine investigations. The measurement devices included in the experimental phase were vane anemometer, vortex shedding anemometer, a prototype thermoan-emometer, smoke tube, and oil of wintergreen sprayer. The measurement methods included single-point centerline, timed-point traverse, continuous traverse for the anemometers, and various distances and cloud positions for the smoke tube and oil of wintergreen devices. The study resulted in guidelines for measurement site selection that are applicable to most inmine situations. It also showed that the use of correction factors is problematic. There are many potential pit-falls and there are cogent arguments against using certain correction factors. However, generalized correction factors were developed that can be successfully applied in routine ventilation work, provided that their use is properly understood.

Jan 1, 1985

To provide an engineering solution to wood crib design and deployment strategies that will ensure safety for underground coal mine workers. This is accomplished by preserving necessary ground control requirements while minimizing support costs or by developing new support strategies to enhance ground support in difficult conditions. A secondary objective is to be able to quantify wood crib support performance to define support requirements for alternative support systems. These objectives have been achieved through a simple-to-use computer program called the wood crib performance model (wcpm).

Jan 1, 1997

Most of automotive magnesium applications are presently produced by high-pressure die casting processes, For further expansion of the alloy usage in automobiles, novel-manufacturing processes needs to be developed, In this study, squeeze casting of AM50 alloy was carried out using a hydraulic press with an applied pressure of 70 MPa, Tensile properties and fracture behavior of the squeeze-cast AM50 were characterized in comparison with the die cast counterpart, The squeeze-cast AM50 alloy exhibits virtually no porosity in the microstructure evaluated by optical microscopy, The results of tensile testing indicate that the improved tensile properties for the squeeze-cast samples over the conventional high-pressure die-cast parts, The analysis of tensile behavior shows that the strain-hardening rate during the plastic deformation of the squeeze-cast specimens is constantly higher than that of the die-cast specimens. The SEM fractography evidently reveals the ductile fracture features of the squeeze-cast alloy AM50.

Jan 1, 2005

By Oscar H. Hershey

COMPLAINT has been made that in the literature of economic geology the work of the "company or practical" mining geologists does not get enough attention. I propose to attempt to overcome this com¬plaint in reference to one important lead-mining district, that of the Coeur d'Alene in northern Idaho. Furthermore, I will assume that the reader is not so much interested in the geology of the district as in the methods of application used and incidents that have arisen in the work. All the important discoveries of ore in the Coeur d'Alene were made without benefit of geology. Certainly I would not claim the reputed discoverer of the Bunker Hill mine as a fellow geologist. It appears also that the mines were operated quite successfully for many years without geological specialists, though doubtless certain properties were visited at long intervals by such men as Waldemar Lindgren. It was known that the ores occur in quartzite, graywackes and slates as stated by J. R. Finlay in 1903. (TRANS., VOL. 33.) He described the ore as occurring in typical fissure veins that occupy fault-planes of indeterminate displacement. The Bunker Hill lode was based on a definite fissure with the mineralization all on the hanging-wall side, extending as far as 300 ft. from the fissure.

Jan 1, 1933

By Brian Fulcher

While tunneling in Europe has been a tradition for centuries, many companies and countries have embraced tunnel innovation with considerable vigor and creativity. Indeed, local needs and site conditions have provided the initiative for improved means, methods, materials and equipment to complete progressively more challenging projects. Many recently completed tunnels have expanded tunneling technology and contributed to the development of highly specialized and productive equipment ? such as the mixed-mode tunnel boring ma-chine (TBM) presently in operation at the SOCATOP A- [ ] 86 road tunnel and the high-pressure slurry TBMs for the Westerschelde Tunnel in the Netherlands and Hollandsas near Malmo, Sweden. This paper describes some of the key technologies employed by European tunnel builders and designers including the New Austrian Tunneling Method (NATM), advanced earth pressure-balanced (EPB) machines, pres-sure-faced (slurry) tunneling machines as well as ?hybrid? or mixed-mode TBMs. While these tunneling methods and equipment generally involve significant equipment investment, they may also involve highly trained, experienced and specialized tunneling and support crews as well as materials and tools specifically developed to supplement or complement tunneling performance. For example, mechanized pipe arch placement substantially improves ground support measures and NATM advance and on larger tunnel cross-sections.

Jan 1, 2007

By Lee B. Paterson

Mining Engineers throughout the world have an appreciation for the importance of the role of the Blasthole Drill in one of the primary elements of the mining process. This paper highlights areas that could influence the overall cost effectiveness of that process of breaking rock and the associated downstream mining and ore recovery activities - and how the drill is designed and configured to meet that challenge. Factors influencing drill productivity and overall cost effectiveness are addressed, particularly regarding the benefits which are not necessarily reflected in the drilling process and therefore more difficult to quantify. This paper explores some of the downstream benefits of what we do to the drilling process.

Jan 1, 2000

By Joanna Bzówka

Nowadays, there are some new requirements for the supermarket floors. The floors are loaded by high point- and moving-loads. In spite of this fact, it is necessary to ensure the stiffness of the floor and the stiffness of its support. When pile foundations are designed in the case of weak soil, the piles are recommended under the foundations of the supermarket and also under the floor layers. The example of foundation of a typical supermarket located on long­standing municipal dumping ground is presented. Indirect foundation - CFA piles, 0.5 m in diameter and 4.5 to 20.0 m long, was de­signed. Fifteen trial loading tests were carried out.

Jan 1, 2006

By J. Winterton

Cripple Creek and Victor Gold Mining Co. is developing a full-scale pad injection program as part of the overall operational plan for the Valley Leach Facility. As part of the development process the mechanics of the injection methodology are evaluated in the context of physical injection measurements, outcome from geophysical monitoring, and gold leaching theory. The results indicate that hydraulic fracturing analogies advanced heretofore do not accurately describe injection phenomena in unconsolidated and noncohesive material typical of leach pads. A new interpretation is presented and extended to define operational strategies for maximizing gold production.

Feb 27, 2013

By J. A. McCamley

Gypsum scrap generated from wallboard manufacturing, construction and deconstruction activities in North America, Europe and Japan is a recognized environmental problem. Landfill disposal of this gypsum scrap is problematic, with deposits often creating hydrogen sulphide emissions and metallic sulphide groundwater leachates. Of these regions, Europe is the most advanced in dealing with the issue having enacted legislation, which will come into effect in July 2005 that will strongly encourage gypsum recycling throughout the EU. An estimated 10% to 17% of all gypsum used in the wallboard industry becomes recyclable scrap, which represents approximately 1% of the total waste stream in North America. In the United States, 2.5 to 4.5 Mt of gypsum scrap is generated each year; the volume is similar in Europe (the percentage of total tonnage is less because of the higher use of brick and concrete). The Greater Vancouver region of British Columbia has banned gypsum from its landfills, and as a result, all gypsum scrap is now recycled. New West Gypsum Recycling, a Canadian firm, uses its proprietary technology to process large quantities of gypsum scrap that is reincorporated into new wallboard, at percentages ranging up to 25%. The operation of New West Gypsum Recycling Inc. of Langley, Vancouver is examined as a case study and recommendations are provided as to how other urban regions can implement similar gypsum scrap recycling programs.

Jan 1, 2004

By Seppo Lähteenmäki, Pertti Koivistoinen, Jaakko Levanaho

"This paper describes the benefits and disadvantages of fully autogenous grinding when compared to grinding with steel grinding media. The study is a real case study based on a low tonnage, high grade mining project in a remote location in a developing country. The study compares the capital and operating costs of using either SAG mill, Ball mill, Crusher (SABC) or fully autogenous (AG) grinding circuits and produces an economical analysis of the project for both options. The economics have been developed for the overall project, including mining, processing, environmental and the infrastructure as well as for the additional cost of constructing a fully autogenous grinding circuit instead of the original plan of a SAG Mill, Ball Mill circuit.The paper also describes the development of the autogenous grinding circuit at Outokumpu Oy, Pyhäsalmi mine. This experience was used to design the autogenous grinding circuit for the case study. Pyhäsalmi Concentrator has over 30 years of experience in operating autogenous grinding circuits and therefore provides a sound base for the new circuit design.INTRODUCTIONGrinding of ore using steel grinding media is currently the most commonly used method in the mining industry. Autogenous grinding, ore replaces iron media, is also common especially in Europe and Africa. Iron ore industry in North America uses autogenous grinding in primary and/or secondary stages extensively. In gold, copper and other base metal industries, autogenous grinding is not as common, although there are operations where pebble grinding is or has been used in the secondary grinding stage. There are many variations of autogenous grinding in use in the mining industry. These variations include different mill sizes, mill length to diameter ratios, ore lump sizes, screening and pebble crushing configurations."

Jan 1, 2000

By JAMES BRADLEY

THE Spanish mine is in Nevada County, California, 21 miles northeast of Nevada City by road, and 3 miles north of the town of Washington. The mill and surface buildings are on Poorman's Creek at an ele¬vation of 3,000 ft. About 35 men are employed at the property, which is producing 50 tons of ore per day. Electric power, purchased from the Pacific Gas and Electric Co., is brought in from Alleghany, seven miles away. In the early days the mine was operated by F. W. and P. R. Bradley. Between 1883 and 1899 the production was approximately $900,0)0 in gold. The ore treated during; that time yielded an average of 60 cents per ton and was mined and milled at a profit. The surface, oxidized, ore deposit was 30 to 100 ft. wide and was mined by the glory-hole method. The milling-plant at first consisted of a Blake crusher an-1 a small Huntington mill; later three large Huntington mills were added to the plant. In 1893 a new mill was built at a lower adit- It consisted of 10 stamps and four Huntington mills. The gold was secured by amalgamation, the recovery being about 50 per rent.

Jan 1, 1931

By J. A. Botín

Identifying, quantifying and minimizing technical risks associated to investment decisions is a key challenge for the minerals industry decision takers and investors. However, risk analysis in most bankable mine feasibility studies are based on stochastic modelling of project NPV which, in most cases, fail to provide decision makers with a truly comprehensive analysis of risks associated to technical and management uncertainty and, as the result, are of little use for risk management and project optimization. This paper presents a value-chain risk management approach where project risk is evaluated for each step of the project lifecycle, from exploration to mine closure, and risk management is performed as part of a stepwise value added optimization process.

Jan 1, 2011

By H. J. Lechtenberg

Preliminary results are given of solvent stimulation of two wells producing viscous oil (14°-17° API) from the Tar zone in the Wilmington field, California. The solvent (coker oil, an intermediate refinery product) was injected into the formation, and after a soak period, the well was returned to production. Data are given on crude oil properties, solvent properties, determination of volume of solvent in the produced oil, rate of oil production before and after stimulation, volume of additional oil produced, and volume of solvent recovered. Although further study and improvement of the method arcs needed, cyclic solvent stimulation appears to be an unqualified success in one well and a moderate success in the other.

Jan 1, 1972

By Glenn D. Lyle

As part of an initiative to improve value in mining, CEMI is developing a handbook on best practice in mine design. Various formats were examined, and of these, the wiki was selected as being most suitable. Being web-based, its global reach and capability of being continuously updated allows the wiki to evolve as new knowledge is generated, and to capture the diversity of experience of practitioners in the mining industry. While wikis have many advantages in terms of organizing content and searching, their ability to be edited by users is often seen as a negative characteristic for quality control. To ensure reliability of information content, author attribution, specific authorship models, and a peer review process have been implemented, in addition to the standard version tracking capability of wikis. The first phase of the project concentrates on topics related to underground hard rock mine design. The scope will be expanded to cover other aspects of mining as the project matures. Strategic partnerships with various organizations, such as the CIM, and CANMET, are being formed to provide a wide range of seed material to stimulate growth of the site. www.minedesignwiki.org

May 1, 2011

Mr K.R. Beard was born on 19th December, 1958. He attended Marist Brothers College, Observatory, and Marist Brothers College, Linmeyer. He was awarded a bursary by SEIFSA (Steel and Engineering Industries Federation of South Africa) and gained the degree of B.Sc. Eng. metallurgy at the University of the Witwatersrand in 1982. He is a member of the Engineers' Society of South Africa. Mr G.A. Brown was born on 27th June, 1934, and matriculated at St John's College. He obtained the degrees of RSc. Eng. (Met.) at the University of the Witwatersrand in 1957, and M. Met. at Sheffield University in 1959. He is a member of the Institution of Mining and Metallurgy (UK) and the Society of Mining Engineers (USA). Or LA. Cramer was born in the USA and, having received a B.Sc. degree in metallurgical engineering from the Colorado School of Mines, he emigrated to South Africa in 1971. He enrolled as a graduate student at the University of Natal and successfully completed both an M.Sc. and a Ph.D. degree in chemical engineering.

Jan 1, 1989

By Thomas M. Barczak, Dennis R. Dolinar, Gabriel S. Esterhuizen

Longwall mines typically use some form of standing support for secondary roof support in longwall tailgate entries. Although there have been several new support products developed for this application, there remains no universal design criteria to optimize the application of these support technologies. The requirement for optimization and proper support selection is to understand the degree of control that the support has on the ground behavior. The ground reaction curve and numerical modeling was used to evaluate the impact of standing support on ground behavior. LaModel was used to evaluate the impact of standing support on main roof and floor behavior and pillar yielding. The conclusion drawn from this study was that standing supports do not have sufficient capacity to control main roof or floor loading or prevent the resulting convergence of the tailgate entry. However, it is imperative that this “uncontrollable convergence” be considered in the support design to prevent premature failure of the support. A FLAC model was used to evaluate the near-seam roof and floor behavior in conjunction with the global vertical and horizontal stresses. The model suggests that standing roof supports can have some impact on the ground behavior as the elastic response of the rock is exceeded and rock structure deteriorates from the stress concentrations that develop around the tailgate opening. During this phase, the capacity and stiffness of the standing support can be critical to the stability of the opening, as eventually the rock mass will be transformed into a partially detached structure whose weight must be supported by the standing support. This work is part of a ground control program of research at the National Institute for Occupational Safety and Health (NIOSH) aimed at improving mine safety by reducing roof fall injuries and fatalities.

By Ian Farmer, Nigel Glossop, Philip Garritty

Performance of tunnel boring machines - usually expressed in terms of penetration per revolution - is determined by relations between machine thrust and torque, head diameter and rock strength. It can be shown that for a given machine power and head diameter there is only one rock strength at which the machine performs optimally. In weaker rocks the available torque limits performance and in stronger rocks, the available thrust. Performance data shows that, historically, machines have been designed to cut weaker rocks. Optimization of thrust is required to improve performance in stronger rocks.

Jan 1, 1987

By I. Gil, J. -C. Roegiers

Abstract Hydraulic fracturing is a technology that has been utilized for more than 50 years in the oil industry. It was originally used for stimulating hard, brittle formations which typically exhibit low permeabilities and roughly linear elastic behavior. Nonetheless, an increasingly important segment of the industry is currently stimulating very soft and poorly consolidated formations; where the assumptions of ideal elasticity and relatively small fluid leakoff fail to hold (e.g. Gulf of Mexico, West Africa, Alaska, East China). In these rocks, hydraulic fracturing stimulation has been used for several years to control and solve critical production problems such as sanding and formation damage (caused during completion and drilling operations). Although successful1, the application of this method has not been accompanied by robust fracturing modeling techniques. In addition, long term production increases were often not materialized. In other words, engineers have been able, via trial-and-error, to avoid major ‘operational’ problems but with no optimization of such treatments. Thus, most hydraulic fracturing projects carried out in poorly consolidated rocks render unexpected results. A recent worldwide survey on net pressures by the Delft Fracturing Consortium (Papanastasiou, 1997) indicated that net pressures encountered in the field are 50% to 100% higher than the net pressures predicted by conventional fracturing simulators. The difference is yet higher for the case of poorly consolidated formations (Pak, 1997). The theory for the construction of a fully coupled elastoplastic three-dimensional hydrofrac simulator, specifically conceived for unconsolidated rocks, is presented in this paper. This novel model calculates the dimensions and changes in shape of the fracture(s) being created during hydraulic fracturing operations. No assumptions are made regarding either shape or geometry of the crack(s). Three main failure criteria are used simultaneously in this model: tensile and shear stresses, and volumetric strain. Incremental forms of the governing equations of equilibrium and fluid flow are presented. The scheme chosen for solving this problem is the finite elements method, which allows both equations to be solved simultaneously at any instant in time. Résumé La fracturation hydraulique est une technologie qu’a été utilisé pour plus que 50 ans dans l'industrie pétrolière. Elle a été utilisée au début pour stimuler les formations dure et fragile que typiquement ont des perméabilités basses et un comportement élastique à peu près linéaire. Néanmoins, un segment plus important de l'industrie stimule actuellement des formations mal consolidées; où les suppositions d'élasticité idéale et de relativement petite fuite de fluide ne se tiennent pas raison (par exemple le Golfe de Mexique, l'Afrique d'ouest, Alaska, la Chine de l'est). Dans ces roches, la stimulation avec fracturation hydraulique a été utilisée pour plusieurs années pour contrôler et résoudre les problèmes critiques de production comme les dommages de formation et d’ensablement (causé pendant les opérations de l'accomplissement et forage). Bien que prospère, l'application de cette méthode n'a pas été accompagnée de techniques robustes pour le modelage de fractures. En outre, les augmentations à long terme de production n'ont pas été souvent concrétisées. En d'autre termes, les ingénieurs ont pu, via le procès et l’erreur, éviter les majeur problèmes ‘opérationnel’ mais avec aucune optimisation de tels traitements. Ainsi, la plupart des projets de fracturation hydraulique ont été exécuté dans des roches mal consolidées et ont rendu résultat totalement inattendu. Une récente étude mondiale sur les pressions nettes par le Consortium Delft pour Fracturer (Papanastasiou, 1997) a indiqué que les pressions nettes qu’ont été rencontré dans le champ sont environ 50% à 100% plus hautes que les pressions nettes prédites par les simulateurs fracturant conventionnels. La différence est pourtant plus importante pour le cas de formations mal consolidées (Pak, 1997). La théorie de construction d'un simulateur elastoplastic d’hydrofrac à trois dimensions entièrement couplé, en particulier conçu pour les roches non consolidés, est présentée dans ce papier. Ce nouveau modèle calcule les dimensions et les changements dans la forme de(s) fracture(s) étant créé pendant les opérations de fracturation hydraulique. Aucune supposition n’a été faites en ce que concernant la forme ou la géométrie

Jan 1, 2003

By Ludwig M. Strah

"Wear is a universal problem and is present in all cases wherein one weighted surface moves with or relative to another surface. A practical description of wear as applied to mineral processing plants is outlined.With the advent of higher material and maintenance costs, more attention is being focused on the field of wear resistant linings. The aforementioned is magnified today as the production facilities continue to be designed to handle larger daily capacities. These changes, higher costs and larger plant handling facilities have necessitated the introduction of different materials and designs to combat the never ending battle against wear.In order that wear be understood, it can be relegated to two specific types:1 - Mechanical Wear - due to movement of one loaded surface relative to another.2 - Chemical Wear - more easily defined as corrosionMechanical wearMechanical wear can be subdivided into two basic forms:A.,Material movementB.,Material impactMaterial movement Abrasion is the result of, as earlier stated, the straight move¬ment of one loaded material relative to another.Material impact Is the striking effect when a mass strikes another from various angles and at various speeds. Impact can be severe enough to permanently damage and distort the basic component installed to overcome impact."

Jan 1, 1983

By J. Fletcher Smoak

Consumption of abrasive materials in the United States increased 22% in value over that of 1982 to $320 million; of which, 59% was manufactured abrasive, 35% was industrial diamond (natural and synthetic), and 6% was natural abrasive. Production value of natural abrasives, excluding industrial diamond, remained virtually unchanged. Production of crude tripol, a porous siliceous rock, decreased slightly; however, shipments of processed tripoli increased 13% in quantity and 32% in value. Production of garnet, an abundant iron-aluminum silicate, continued to increase primarily because of further increases in production from one plant that had completed an expansion program in late 1981. Production of special silica stone, both crude and finished, decreased in 1983 because of reduced demand for oilstones

Jan 1, 1984