Search Documents

By Enrique Touceda

FOR a number of years prior to the world war, the firm of Geo. H. Thacher & Co., of Albany, N. Y., was engaged in the manufacture of marine and other gray-iron castings. At -the outbreak of the war the firm decided to specialize in the manufacture f propeller wheels. It attacked the problem, therefore, from a foundry point of view, seeking to produce a casting that would be so accurate that no subsequent machining would be required on the blades, also from the point of view of the ship builder. There were two general methods f manufacture, the shortcomings of which have been freely acknowledged. In the sweep method, the nowel, or bottom half-mold, for each blade is swept up by a spindle beam and pitch race, while the top half-mold for each blade is built up individually. In the pattern method one individual blade, with the hub or hub portion, is mounted on a spindle and the individual -blade mold formed, the pattern is then rotated on the spindle to the position- for the next blade, etc. In rare cases wheels were made from a solid pattern. Owing to the cost of the pattern, its failure in many instances to be correctly made, and (when made of wood) its early and sure distortion the disadvantage of this practice is obvious, while metal patterns in most instances were prohibitive in cost. In these methods both green-sand and loam molding was practiced. The casting produced by either method can be considered only as a blank from which the propeller must be machined. The back surface f each blade must be chipped too the templet and through this procedure chipped to such accuracy, as will be required for a static balance. Inasmuch as the' work done by the machine tool is confined to the driving face of the blades, not only is perfection most difficult, but corrosion will be greater because of the removal of the dense skin f the casting and the local strains set up by the pneumatic tool in chipping. To produce a finished 9-ft. propeller for a Navy destroyer required from 8 to 21 days f foundry work and about the same length of, time for the machining. Through the use f the Thacher process, only as many hours are required, besides it is possible to produce a finished casting in perfect conformity, with any particular propeller-wheel design,

Jan 4, 1921

By J. B. Forrester

In the operation of the coal mines in Utah few adverse conditions confront us. Physical conditions for the economical extraction of the coal are as near perfect as it is possible for them to be. Still several obstacles are encountered to keep up our interest and prevent us from getting in a rut. Of these I shall speak only of Burning, Wants, and Sluffing of Ribs. Should one travel the outcrop from Ivy Creek in Emery county to the Utah-Colorado line, there would be one outstanding feature indelible impressed upon one's mind. That feature is the omnipresent indications of burning in place. Viewing the eastern escarpment of the Wasatch Plateau from a distance, many splotches of dark red are plainly seen always lying above the coal floor. This stratum is a felspathic sandstone, appearing as a white line running the full length of the above escarpment and about midway between the floor of the valley and the top of the plateau. The coal bearing complex consists of shales, sandstones and coal. This complex varies from two hundred to eleven hundred feet in thickness. The number of coal seams are exceedingly variable. As a rule the argilutites form the bulk of this complex. This material is baked by the burning of the coal and the iron present is oxidized to the ferric state, coloring the shale to a dark red. This baked material forms a shingle tales that in places cover the entire complex. It is natural to expect that the most extensive burning is in the canyons facing to the south and east and on the south slopes of the ridges running to the east or west. Such, indeed, is the case. Still in this arid region many crop fires have existed upon the north slopes, especially in those canyons that face to the east. In fact today, instances are not rare where grassy north slopes, heavily timbered with balsam and fir that have attained a diameter of 14 to 24 inches, are found growing upon the disintegrated baked shingle and later development proves that the coal has been burned at least 500 feet back from the outcrop. Still these conditions are not normal. In this arid climate the south and east exposures are steep and barren, except for the scrub pine, cedar, mahogany and kindred semixerophytes. Bunch grass is also a lover of such exposures. There is very little soil found in such places; it is either blown away as fast as formed or washed away by the rare torrential rains, or the rapidly melting snow. Thus we see that the physical conditions are favorable for the starting and maintainence of outcrop fires. This brings us to the probable origin of this phenomenon. There are four probable ways' that such fires, could be started, namely:

Jan 1, 1921

Digital Simulation of Particulate Processes The inherent complexity of mineral particulates (shape, size and mineralogical texture) has challenged conventional simulation model approaches for decades. Much effort was expedited in using mathematical assumptions to accommodate stereological effect. With the advance of instrumental methods such as x-ray microtomography 3D structure can, in many cases, be measured directly. The information derived from such measurements provides direct input to building the structural digital model. In addition digital simulation methods that enable creation of process realistic particulate properties in an efficient digital computer space have demonstrated their effectiveness to model a variety of realistic packing, sorting and multi-phase processes. The paper reviews recent advances in the use of information derived from 3D micro-tomographic imaging and laser scanning technology can be coupled with digital methods to enable simulation of tablet compaction and dissolution, filtration and permeability, column packing and leaching kinetics, packing and cementation of nuclear waste. By assigning 'properties' to a digital zone (voxel) in the computational space it is possible to mimic the realistic characteristics of quite complex particulate mineral processing systems. The system self-adapts to correct the coherent particle characteristics (shape, size, compound, porosity) with time. Such simulations are useful to elucidate the sensitivity of system performance to variations in process parameters. Dimensional scaling of the approach is also possible, as the case studies will illustrate, in deploying the method to both small (micron) and large (m) features. The use of process realistic simulations presents experimental challenges in code validation. It is in this context that other tomographic methods play a role in direct 3D measurement of system behaviour such as electrical and optical sensors.

Sep 13, 2010

This paper aims to collate the metallurgical test work undertaken on the Barrytown mineral sands deposit. It is intended to serve as a summary of mineral dressing work undertaken by all interested parties up to the time of writing. Areas requiring further investigation are: in situ grades and recoveries of accessory minerals,the question of 'rank' of ilmenite within the deposit,flow sheet development for the recovery of gold and monazite, andcost analysis to investigate the relative worth of other minerals; notably rutile. Flow sheet development with respect to the Accessory Minerals cannot be accurately defined until the importance of each mineral in terms of grade, recovery and expected revenue is determined. To date, ilmenite and zircon flows are well documented. Further work is needed to quantify recovery's and flows of the other minerals; notably monazite, gold and rutile.

Jan 1, 1989

By Ulises Crossa Archiopoli

We describe a technique that allows rapid imaging of the thermal diffusivity of the sample by a modified photo-thermal technique. The thermal diffusivity in hardened steels strongly correlates to the hardness. Hence in a noncontact manner and with optical microscope resolution, a 2D map exhibiting the crystallographic phases and hardness of the sample can be retrieved. Two almost collinear laser beams scan the surface, one as a modulated pump and a second as a CW probe. The deflection of the probe carries information on the thermal expansion of the sample and with it, on the thermal diffusivity. It is shown that a single determination of the time delay of the modulation of the probe beam can be used to retrieve the thermal diffusivity.

Jan 1, 2010

By Len Harris

Webster?s Dictionary describes culture as: ? The totality of socially transmitted behavior patterns, arts, beliefs, institutions and all other products of human work and thought typical of a population or community at a given time. ? A style of social and artistic expression peculiar to a class or society. ? Intellectual and artistic activity. ? The art of developing the social, moral and intellectual facilities through education. The authors have nearly 100 years of combined experience in the mining industry working with and consulting to mining companies and companies engaged in the supply of goods and services to the mining industry worldwide. In this report, they present their experiences and ideas on the importance of cultural aspects in the successful development and implementation of mining ventures. Their suggestions on how to handle culture shock will be of interest to expatriate managers, operators, social workers, and engineering and construction personnel posted to overseas operations, as well as to nationals posted to other parts of their own country.

Jan 1, 2008

By Lavers G

Factors governing the dissolution of nickel and iron in pentlandite and pyrrhotite concentrates from Mt. Windarra were studied for aqueous solutions at normal temperatures and pressures. The effects of dissolved dioxygen, carbon dioxide, hydrogen ions, and chloride ions are described. The direct reaction of aerated water wiili pyrrhotite is much faster than with pentlandite, and reaction rates are proportional to the dissolved dioxygen concentration. In both cases divalent metal sulphates are produced initially. The subsequent oxidation of iron(II) to iron(III) and its oxolation produces acid solutions which rapidly attack both minerals. The presence of carbon dioxide or chloride ion has little effect on these rates.

Jan 1, 1976

By R. M. Tyler

The importance of the heavy mineral sands to southern African economic well-being cannot be over emphasized. The value of the worldwide titanium dioxide industry is estimated at $7 billion. Six out of eight of the world?s proposed new project areas are in southern and eastern Africa, and a seventh at Tamil Nadu in India is partly owned by a South African company, Kumba Resources. The HMS industry can be highly lucrative; its return on capital is the best in the mining industry. There are, however, problems, particularly in the smelting technology. The often considerable affect of mining on environmentally sensitive coastal dunes is also becoming increasingly important. The medium-to long-term demand for Ti-dioxide pigment and ceramic grade zircon appears very healthy. If, as predicted, the costs of producing titanium metal can be reduced, then there is huge potential for the metal. In summary, the HMS industry is an attractive one to be in, with good returns and generally manageable risks. New business opportunities and their economic implications for Africa are discussed.

Jan 1, 2004

By A. de Meyer

Zincor experienced significant losses of metallic zinc to dross during the melting of zinc cathode plates. In this study five factors affecting the formation of dross are identified from literature. Dross from both the plant and that produced in the laboratory is characterized using XRD. An empirical model, based on laboratory-scale investigations, was developed to quantify the effect these factors on their own or in combination with each other has on the amount of zinc loss to dross. The predictive capability of the model is evaluated based on the laboratory-scale investigations. Predictions are made on the effects that heat treating the cathode plates prior to melting, increasing the cathode plate thickness, washing and drying prior to melting, and loading the furnace in a controlled manner have on the amount of zinc loss to dross. Keywords: Zinc, dross, optimize, smelter, yield, losses, empirical, model, XRD.

Jan 1, 2010

Baja Mining is currently constructing the Boleo metallurgical plant in Santa Rosalia, Mexico to recover copper, cobalt, zinc and possibly manganese products from the Boleo ore. The process involves an acid seawater leach of the whole ore followed by solid-liquid separation and washing of the leach residue. Solvent extraction is used to separate copper, cobalt and zinc from solution. Copper and cobalt are recovered as cathode metal products and zinc as a zinc sulphate monohydrate. Manganese may be directly precipitated as manganese carbonate which can be used as a feedstock for manganese metal production. Laboratory testing has continued to refine various aspects of the process including iron removal, cobalt and zinc solvent extraction, cadmium cementation, cobalt electrowinning and manganese metal electrowinning. The results of this testing are reported in this paper.

Jan 1, 2012

By Leslie McHattie

?Intelligent mine? conjures up a futuristic image of unmanned extractors and loaders working in harsh conditions in a remote lunar landscape. The promise of increasing mine fleet productivity and solving the problem labor shortages in mining regions can certainly be achieved today through remote controlled extraction and automated hauling. The technology is available and it doesn?t seem to be so much science fiction when Google?s self-driving cars hurtle down the freeway. ?Intelligent mining,? on the other hand, implies the application of information technology at every phase of the mining value chain, from exploration and geological modeling to equipment, operations and maintenance, and logistics and transportation. These are really industry-specific, enterprise-class software solutions focused on using information technology to support the business processes of mining and make them more efficient and effective. Overlaying the physical world with the digital or virtual world enables us to model and simulate our assets, giving us the ability to effectively design, build, and ultimately optimize the performance and reliability of our assets throughout the lifecycle. The digital asset, often a 3D model, is created initially during the engineering and construction phase, and is handed over to the operator before the mine goes into operation. Combined with geospatial or geographic information systems, the operator has a complete digital representation of the physical world, which forms the foundation for risk and performance management, along with compliance and regulatory reporting. Laser scanning and positioning technology can be used to create point clouds ? information models consisting of millions of data points ? which enable the visualization and representation of the ?as-operated? reality. But consider that once the mine is in operation, it throws off an endless stream of data in the form of performance and condition data from sensors and monitoring devices on fixed and mobile assets through networks, servers, and services. This ?big data? can be processed and analyzed to spot trends, help predict events, and formulate reliability strategies as early as the design stage (e.g., reliability-centered design). ?Intelligent mining? implies that massive amounts of data augment the reality of the physical mine, plant, and equipment. This embedded intelligence can be used to optimize operational efficiency, increase asset availability and utilization, improve safety and environmental integrity, and maximize return on investment. Lastly, the sweet spot for intelligent mining is seen in the convergence of consumerization and industrialization. The application of ?consumer? technologies that we use every day on our iPhones and Android devices, such as cameras, motion sensors, and positioning in an industrial context, are producing ?immersive? experiences. Overlaying the digital world on the physical world and connecting them accurately through intelligent positioning results in ?intelligent infrastructure,? which is safer and more sustainable. Bentley Systems works with many mining companies and engineering, procurement and construction companies involved in all aspects of mining infrastructure development. In fact, 10 of the top 20 mining companies ranked by market capitalization are users of Bentley software, including all of the top five. In addition, Bentley provides software solutions to the world?s leading engineering, procurement, and construction companies, as well as owner-operators, who design, build and operate the world?s infrastructure. Bentley?s solutions for mining and resource extraction industries help increase the efficiency of capital projects associated with the design, procurement, and construction of mines and processing plants, as well as the operation and maintenance of mining fleet and equipment.

Aug 1, 2013

By S M Richardson, A W McNeill, J B. Gemmell

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Hellyer, Fossey, Que River and Mount Charter volcanic-hosted massive sulfide (VHMS) deposits occur within the Que-Hellyer volcanics of the Mount Read volcanics, Tasmania. These deposits occur along a 6 km strike length and are hosted by the same stratigraphic unit. We use a combination of whole-rock geochemistry, short wavelength infrared (SWIR) spectrometry, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses and compiled historic whole-rock geochemical data to develop district-scale vectors towards VHMS mineralisation.Strongly sericite and K-feldspar altered rocks concentrate along a linear trend from Hellyer, through Que River, to Mount Charter. Ishikawa alteration index values and whole-rock major and trace element concentrations provide exploration vectors towards mineralisation on a regional scale as significant enrichment and depletion trends. On a deposit scale, composition variations in white mica (sericite alteration), chlorite and K-feldspar are observed and reflected in whole-rock geochemical variations. Regional SWIR data from drill core support the prevalence of phengitic mica and high-Mg chlorite within footwall alteration halos and highlight the main upflow zones of hydrothermal fluids in the VHMS district. The combined use of regional whole-rock geochemistry, SWIR and mineral chemistry is an effective way to highlight prospective areas for VHMS mineralisation in a mature exploration province.CITATION:Wu, S, Gemmell, J B, McNeill, A W and Richardson, S M, 2015. Exploration implications from variations in whole-rock and mineral chemistry around the volcanic-hosted massive sulfide deposits of the Que-Hellyer volcanics, Tasmania, Australia , in Proceedings PACRIM 2015 Congress, pp 85–90 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By R. L. J. Phillips

"The environmental impact of the Rabbit Lake project is presented. Baseline data for fish, water, air and radon collected in 1973, 1975, 1980and 1986, are compared with post-development environmental monitoring data. Predicted environmental impacts for the developed Rabbit Lake and B-zone deposits are compared to the actual impacts. INTRODUCTIONThe environmental impact of the Rabbit Lake project has been documented through the years in several submissions to the government agencies. In 1972, the environmental baseline study for the Rabbit Lake area was completed prior to any mining activity at the Rabbit Lake pit (Fig. 1).Sampling concentrated on Hidden Bay and Pow Bay, which received the treated effluent and the waters drained from Rabbit Lake respectively.A second baseline study was done on the Collins Bay area in 1980(Fig. I) in preparation for the mining of the B-zone pit. The detail in this study was considerably greater than the detail in the previous study. Collins Bay and Harrison Peninsula were the areas sampled. The B-zone deposit is being mined at present.With the discovery of the A-zone, D-zone and Eagle Point deposits, it was decided in 1986 to begin proceedings to obtain approval from Saskatchewan's Department of the Environment, and from the Atomic Energy Control Board to develop these deposits.In preparation, a third baseline study of both the Rabbit Lake and Collins Bay areas was done in 1986 and 1987. The emphasis was to establish the baseline at the three new deposits, to quantify the actual impacts of the existing Rabbit Lake operations and to confirm the Collins Bay B-zone (1980) impact predictions. The new deposits will allow us to continue to produce uranium into the future. In January 1988, Saskatchewan approval was received.Since 1975 in the Rabbit Lake area and 1980 in the Collins Bay area, routine environmental monitoring has been done. This has resulted in one of the largest and most comprehensive environmental data bases in North America in mining. By the time the Eagle Point deposit is mined to completion, there will have been data collected for approximately 40 years.Further discussions follow which describe the impacts of the past (1972 to 1984), the present (1985 to 1987) and the future. In addition, the past and present performances and the future plans of the .waste management systems will be discussed."

Jan 1, 1989

By William J. Krisko

This contract final report summarizes the design, fabrication and testing of canopy air curtain devices under Bureau of Mines Contract H0232067. The canopy air curtain device is designed to reduce the level of respirable dust exposure to a continuous mining machine operator while having a minimum effect on operator safety, mobility and comfort and being compatible with mining equipment. This contract was devoted to the development of a device which utilizes an invisible curtain of air to envelope a mining machine operator's breathing zone with filtered air to provide respiratory protection. Various concepts were evaluated by means of laboratory tests. One concept was selected and was tested on various mining machines at underground sites by means of MSA personal samplers. The canopy air curtain was found to be effective. The percent reductions over the ambient dust concentrations were about 30 to 75 percent depending on the amount of time the operator spent under the air curtain. At one test site, the device enabled the mining machine to operate within compliance. Donaldson Company is presently working on the commercial production of the device.

Jan 1, 1975

By Marco Taipe

Uno de los mayores costos del proceso minero es el de perforación, en tanto emplea aire comprimido. Por tal motivo, la industria minera busca diferentes alternativas para reducir los costos del aire comprimido o eventualmente a través del uso del sistema electro-neumático. Este sistema es de fácil instalación y mantenimiento puesto que se basa en electricidad y agua, reduciendo costos y a su vez mejorando las condiciones de trabajo a través de la versatilidad del presente sistema.

Sep 12, 2011

By R C. A Minnitt

The Witwatersrand Supergroup is host to the world’s largest gold deposits. The location, quantity, grade, continuity and other geological characteristics of a Mineral Resource are either known, estimated from specific geological evidence and knowledge, or interpreted from a well constrained and portrayed geological model. Establishing such a model is an integral part of the evaluation process in the Anglogold Ashanti (AGA) group, and is referred to as a Geoscience Business Model for the mining operations. The geological model established over the years has relied on detailed descriptions of the mineralisation, and understanding of the regional and local geology of the Witwatersrand sediments, in the West Wits and Free State goldfields. The processes of data collection in regard to underground stope and developing mapping, structural and sedimentological mapping, and the geological inputs to mine planning systems are described, together with aspects of drilling, sampling, grade control, and data management. Anglogold Ashanti’s Geoscience Department employs a complex and unique process to generate the Mineral Resource, including a 3D geological structure model of the orebodies which are usually highly faulted, and a robust mineralisation/facies model on which the decisions about domain boundaries are established. A Mineral Resource Inventory System (MRIS) has a dynamic graphic interface to the resource database that is used for compiling the resource statement. It is also used to determine the gold-called-for, as well as short and long-term planning. A unique estimation process using the extensive closely spaced stope face sampling database and the more widely spaced surface drilling information is used in combination in the Macro Co-Kriging estimation. The use of different support sizes in the C0-Kriging process is preceded by the equally unique ‘clusterisation’ and ‘acceptorisation’ procedures by which the data are quality controlled and assured prior to their use in the kriging process. The Mineral Resource and Ore Reserve estimates are classified according to the SAMREC code through a method that ensures that they are compliant, auditable, transparent and reconcilable with previous Mineral Resource and Ore Reserve statements.

Aug 22, 2011

By John F. Gamble

Paper 1?South African experience with asbestos-related environmental mesothelioma: Is fiber type important? Neil White, Gill Nelson, Jill Murray The purpose of this review was to illustrate the importance of the type of asbestos in environmental mesothelioma. South Africa is a logical place to assess fiber type. The three major types of asbestos (crocidolite, amosite and chrysotile) were mined (all asbestos mining stopped in 2002) in South Africa. The association between asbestos and mesothelioma was discovered in South Africa. The occupational literature indicates high mesotheliomagenic potential for crocidolite, less for amosite and less still for chrysotile. Since South Africa has been a major source of crocidolite, relatively high rates of mesothelioma in the mining population is not surprising. High rates of mesothelioma due to environmental exposure is surprising, except perhaps when the authors? point out potential sources for community exposures (e.g., mine tailings used for road surfacing, golf courses, brick and plaster making; insulation in residential ceilings; children playing on fiber-rich waste rock). The authors? reviewed four studies reporting on mesothelioma cases and their sources of exposure and fiber type. Overall 23% of the known cases were attributed to the environmental (not occupational) exposure and about 90% were due to crocidolite asbestos. The proportion of environmental mesothelioma is considerably higher than in Western Australia where crocidolite is also mined. There the overall rate of environmental mesothelioma is about 6% (and less than 1% from residence in a crocidolite mining area).

Jan 1, 2007

By M. B. Fonseca

Risk quantification in grade-tonnage curves is critical for capital investment in mining projects and can be obtained through geostatistical simulations of orebodies. A practical difficulty may arise in multi-element deposits, as the joint modelling of the related attributes using the traditional co-simulation approaches is computationally intensive and may be impractical for use in the industrial environment. This paper presents the construction of risk-integrating grade-tonnage curves for a complex copper deposit in northern Brazil, by jointly simulating its key geochemical attributes of interest: Cu, Fe and K. The joint conditional simulation of these elements is based on Minimum/Maximum Autocorrelation Factors (MAF). MAF is an approach, based on principal components, that spatially decorrelates the variables involved to non-correlated factors. MAF’sspatial decorrelation at any lag distance is the main and critical difference of this approach from the principal component approach attempted in the past. In the MAF approach, the independent factors are individually simulated and back-transformed to the conditional simulations of the correlated deposit attributes that reproduce the cross-correlations of the original variables. Keywords: Joint simulation; mini/max autocorrelation factors; grade-tonnage curves.

Jan 1, 2003

By W. P. Johnstone

The computer assisted generation of geological models to represent the geometry of, and grade distribution within, orebodies is a rapidly growing area of the geological profession. Such models are increasingly used as a necessary starting point in determining the mineability of mineral deposits in terms of practical mine design and economic considerations. The transition from traditional techniques such as field or underground mapping and the manual calculation of grade and tonnage estimates, as well as related activities such as the interpolation of cross-sections, the use of stereographic projections, core logging and hand contouring, to computerized applications, is by no means complete. In fact, many geological professionals deliberately avoid the use of computer simulations based on the perception that the resulting models are simplistic and that their construction is not founded on sound geological principles. The purpose of this paper is to assess current thinking on this topic by considering; (a) an overview of advances in the drafting of geological maps, (b) the theoretical basis for multi-dimensional geological modelling, (c) the case for combining traditional and modern techniques, and (d) the benefits to the mining value chain.

Jan 1, 2003

By Laurel E. Blackman

The DFI Project Information Management Systems (PIMS) Committee cooperated with the US Army Corps of Engineers (USACE) to develop a specification for PIMS used on USACE projects. Once completed the Committee developed a more generic version of this specification for general use, which is contained in this document. This first edition has simply removed the USACE-related requirements from the document. The committee will continue to work on this specification to enhance the content and also incorporate recent technological development for these systems. It is the Committee's intention that a second edition will be issued in 2022.

Jan 1, 2021