Search Documents

A composite iron ore-reductant pellet is a mixture of fine iron ore and fines of coal/char/coke, bonded at essentially room temperature with sufficient green strength for subsequent handling. In ironmaking, these pellets offer the advantage of fast reduction, utilisation of fines, non-coking coal and coke breeze. The composite pellet-based alternative ironmaking processes constitute a promising route for ironmaking in future. The present paper is a brief review of kinetics and mechanism of reduction of iron oxides into iron and other associated reactions, when these pellets are heated to high temperature. It would draw significantly from investigations conducted by the author and his co-workers.

Jan 1, 1999

By Betty L. Gibbs

Geologically simple deposits can be modeled quickly and easily with inexpensive gridding and mapping software. Hundreds of mines around the world use RockWorks99 and Surfer 7 for generating contour maps, producing log plots and cross sections, and performing other useful geological calculations. These programs are used by many mining operations as their only modeling and graphical software or they are used in conjunction with larger systems. The investment in learning time is low and the programs produce reasonable quality results with standard computing equipment. RockWorks99 and Surfer 7 provide a good level of capability while maintaining high quality technical integrity. Both programs are used for many applications in mining, oil and gas, environmental and other fields that require analysis of spatial data.

Jan 1, 2000

In March, the Minister of Mines, Mrs. Judy Erola, released a mineral discussion paper at the annual meeting and convention in Toronto of the Prospectors and Developers Association. Among the mineral objectives discussed was the revitalization of the "junior" mining industry. That industry reportedly has seen its share of total exploration expenditures fall from 50% in 1969 to 10% in 1979. Some sources believe the reason to be the rise of exploration costs and more- restrictive legislation The junior mining industry reportedly was responsible for 40% of all mineral discoveries in the 1969-79 period. CZECHOSLOVAKIA Czechoslovakia expects its capacity for the recovery of gallium metal to increase from 1,650 kilograms to nearly 3,000 kilograms per year by the installation of new recovery equipment at the aluminum plant at Ziar Nad Hronom in Central Slovakia. World production data are not reported, but the United States consumed 8,000 kilograms (estimated) in 1981, of which 5,536 kilograms were imported. Gallium is recovered as a byproduct of the Bayer process for the conversion of bauxite to alumina, and from certain zinc processing wastes. It is used for electronic applications such as light-emitting diodes for visual display panels in calculators, clocks, and other instruments.

Jan 1, 1982

By Horst Pöchhacker

The largest structure along the Tauern highway section between Salzburg and Villach is the 6.4-km-long Tauern Tunnel. The major geotechnical problems that came up surprisingly while driving the headings of that tunnel and their successful solution form the content of this article. A detailed discussion is presented of the special construction methods developed by systematic application of the principles of the New Austrian Tunneling Method with which even very heavily squeezing ground with large excavation areas can be mastered reliably and economically.

Jan 1, 1976

By J. R. Goode

Up to one half of neodymium and praseodymium production, key ingredients in permanent magnets, is produced illegally. About 60% of cobalt production, critical in lithium-ion batteries and other applications, comes from central African states, and much of it is produced illegally. Tantalum, important in modern electronics, is also primarily sourced from central Africa and, again, much of it illegally. Illegal mineral production, as exemplified here, is often used to fund armed conflict. Furthermore, it is typically conducted with scant regard for human rights and environmental protection. It also leads to depressed prices which in turn limits the possibility of legitimate producers entering the market. Systems of traceability and provenance, along with cooperative supply chain participants can limit the production of illegitimate material and thereby improve conditions in the countries of origin and reduce downward pressure on prices.

By S. Makni, A. Faucher, F. Robichaud, A. Bouajila

"Optimizing the ball charge in a grinding mill may be needed to maximise throughput or alternatively, to achieve proper product size in more challenging situations. Efforts to optimise the ball charge however are essentially empirical and suffer from the lack of appropriate, accessible and reliable tools. To address these limitations, a new model-based technology was developed that relies on 3D Discrete Element Method and population balance techniques: it takes on the form of a simulator that aims to significantly decrease the time required to optimise the size distribution and the grinding media load within a ball mill. This paper summarizes the research work related to the development of this simulator. The calibration of the different constituting sub-models will be highlighted. The successful use of the simulator to predict the effect of ball make-up on the grinding product size distribution in one plant is also reported.INTRODUCTION Adjusting the characteristics of the grinding media charge in grinding mills holds significant potential for optimisation of mill performance. For example, properly adjusting the ball size distribution in a ball mill can help achieving specified targets for final product size distribution and/or throughput capacity. However, several problems appear when reviewing the process and the available tools to optimise ball mill load: • The current empirical simulation tools are lacking with regard to the ability to predict the performance of grinding when changes to mill ball make-up are made; • Generally, these tools estimate the top size of the charge so it is difficult to predict the effect of mixed ball make-up; • As the quality of prediction of these tools is low, the operators try to optimise the ball charge by a ""trial and error"" method and proceeding with conservative changes. The influence of these changes on grinding performance is often less than the measurement precision and the improvements then remain imperceptible; • A change in ball make-up may require an average of about 6 months waiting period before reaching the stationary state of mill ball load. This exercise is due to be costly if applied change decreases the mill performance. In its effort towards the comminution process optimisation, COREM R&D portfolio had addressed the herein described opportunity during the last five years This paper describes the technology already developed for the optimisation of ball charge. It takes on the form of a simulator that aims to predict the evolution of the grinding media load, the grinding energy available in the ball mill and the final product size distribution. The simulator was first validated in a pilot scale ball mill and then applied in an industrial case."

Jan 1, 2012

By R. Larry Grayson

In the October 1998 issue of the Holmes Safety Association Bulletin, NIOSH authors Mark Stephenson and Carol Merry wrote the article Hearing loss among miners and measures to protect hearing, which focused on the extensiveness of hearing loss among miners and the use of hearing protection to prevent hearing loss. While the primary importance of engineering controls in preventing hearing loss was discussed, since miners do not generally have control over their work en­vironment or assignments, the article focused on the importance of consis­tent use of hearing protection. In this article, all aspects of a compre­hensive approach to the prevention of hearing loss in miners will be covered. The discussions will do the following: ? describe application of the hierarchy of controls in preventing hear­ing loss in miners, ? give an example for each type of control measure and its impact, ? explain the major provisions, be­yond the hierarchy of controls, of the recent NIOSH document en-titled Criteria for a Recommended Standard: Occupa­tional Noise Exposure, Revised Criteria 1998 relative to a hearing loss prevention program, and ? summarize important points on control of noise exposure for every miner to remember, equipment in most facets of operations. Miners are well aware of noisy areas in or around equipment, icluding extraction machinery such as draglines, power shovels, longwall shearers, and continuous mining machines; powered haulage equipment such as load-haul-dumps, shuttle cars, large trucks, and continuous haulage units; roof bolting machines; jackleg drills and stopers; auxiliary equipment such as compressors, fans, and pumps; size reduction equipment, etc. They are not well aware of the insidious nature of pro­gressive hearing loss, which is per­manent, but they are generally aware of what levels of noise are hazardous and what measures can be taken to reduce their personal noise exposure. Behaviorally, however, there are many reasons why miners choose not to use hearing protection faithfully.

Jan 1, 1998

By Fookes R. A, Gardner K. J, Gravitis V. L, Watt J. S, Steffner E. J

Two radioisotope techniques suitable for the rapid laboratory determination of the ash content of coal have been tested ou unwashed coal samples from four Australian coal seams. In one techniqne, measurements of backscattered 238Pu L X-rays and iron K X-rays from finely ground coal samples have been combined to determine ash content in uuwashed coals to ±0.5 weight per ce111 ash (ls) for three seams and 0.9 weight per cent ash for the fourth.The second technique, which involves measurements of the transmission by the coal of narrow beams of 241Am 60 keV and 123Ba 356 keV ? rays, requires less sample preparat ion. The ash was determined to within the range of 0.8 to 2.6 weight per cent for the four seams (unwashed coal). For washed coals, errors are expected to be < ±0.5 weight per cent ash.

Jan 1, 1982

By William X. Chavez

The Mantos Blancos copper-silver district, a major copper-producing area since 1961, is located on the Tropic of Capricorn about 45 kilometers northeast of the northern Chile port city of Antofagasta, as shown in Figure 1. Copper oxide minerals occurring as atacamite (Cu C1(OH)3) and chrysocolla (copper silicate-hydrate) were discovered in the district in the early 1900's (Knobler and Joseph, 1962). The mine is situated in the northern Atacama Desert, one of the most arid regions on earth, and presently receives less than 1 cm per year of precipitation. The extreme aridity of the Atacama Desert is thought to have prevailed since at least Middle Miocene time (Mortimer et al., 1978) when development of important supervene copper enrichment was slowed in many areas of northern Chile (e.g., Chuquicamata, Exotica). Despite the paucity of precipitation, landform development is mature, with large alluvial fans and alluvial-filled valleys covering much of the region. In addition, the aridity and presence of salts have led to the formation of a sub-surface cementing of alluvium and colluvium by halite-rich caliche ranging from a few centimeters to over 3 meters in thickness. These factors, resulting in poor outcrop exposure, make even reconnaissance mapping difficult.

Jan 1, 1983

By Gordon R. Sima

This contract is concerned with feasibility studies, design and fabrication of a prototype hand-held test instrument and a machine-mounted test Instrument for measurement of electrical shock hazards of mining machines. This report presents the proposed and detailed design of the hand-held test instrument and the machine-mounted test instrument. Theory of operation of each instrument is discussed and includes the operating parameters.

Jan 1, 1976

By D. Anderson Willis, Alan A. Campoli, Douglas Mynear, Seth Mittle, J. Steven Gardner

"The diversification of energy sources in the United States has seen some major shifts during the past decade resulting from:• A sudden abundance of low-cost natural gas becoming available through advanced horizontal drilling and hydraulic fracturing techniques.• Incentive-driven policies leading to new development in alternative energy.• The emergence of alternative energy sources proliferated as a result of state and federal level incentives and falling capital costs.Coal was once recognized as the primary low-cost fuel source for the generation of electricity in the United States for most of the last century, providing upward of 50 percent of the total generation capacity during much of that period. However, within the past decade, lower-cost natural gas has overtaken coal as the primary source of fuel used in electricity generation, and alternative sources have steadily grown to now account for approximately 10 percent of the overall mix.West Virginia and Kentucky have not experienced the full breadth of the fuel shift, and, as of 2016, still obtained approximately 80-90 percent of electric power generation from coal. However, as coal plants are retired, there has been a shift toward natural gas for new power plants constructed in the region. The economics of power generation (i.e., lowcost fuel source) has typically been the major factor in determining shifts from one fuel source or technology to another. However, governmental energy policies and incentives have more recently been used to promote the development of new alternative technologies such as wind and solar energy growth to diversify the energy mix. The implementation of these incentives has provided some needed traction and resulted in driving the cost of manufacturing and installation of these new wind and solar systems downward to be more cost competitive with conventional fossil-fueled power sources. Future shifts in the generation capacity by fuel type will also be inevitable and impossible to project accurately as policies change and innovative technologies evolve. Determining factors may include the expiration of current incentives, decreasing capital costs, future environmental regulations, evolution of energy storage systems, technical challenges associated with increasing intermittent sources of generation and the development of unforeseen technologies. West Virginia and Kentucky have been among the least solar friendly states, ranking 44th and 48th of the 50 states (Fig. 1 for WV). The ranking of other coal producing states are similarly low:• Ohio 20• Pennsylvania 21• Virginia 38• West Virginia 44• Wyoming 45• Kentucky 48• Alabama 50"

Jun 1, 2019

By M. Yavuz

One of the challenging problems for optimization in mining operations is to choose the best equipment among the alternatives. Equipment selection is an important task for mine management due to its operational cost, and is also an integral part of mine planning and design. Equipment selection is not a well-defined process because it involves the interaction of several subjective factors or criteria. Besides, decisions are often complicated and may even embody contradictions. Therefore, equipment selection is considered as a multi-criteria decision-making process, and suitable decision-making methods should be employed in this process. In this study, the loader selection for Aegean Lignite Colliery was made by using both the analytic hierarchy process and Yager’s method. Owing to the misusage of Yager’s method in the past, a new procedure is proposed in this paper for making proper decisions. It is highly recommended in this purposed method that criteria or alternatives should be grouped so as not to exceed the limitations of human performance (nine criteria/alternatives). The most appropriate solution for the loader selection was investigated by obeying this limitation for each method, and the results were compared. At the end of the decision-making process, a sensitivity analysis was applied for each method in order to see how a criterion affects the final decision. The advantages and disadvantages encountered during the application of each decision-making method are presented.

Jan 1, 2015

By R. M. Santmyers

Of the sand and miscellaneous silica produced in the United States , ordinary sand and gravel are , of course , the most important, at least as regards volume of output . The building- construction industry absorbs approximately 75 per cent of the total value of all quartz and silica , as shown in Table 2 of Quartz and Silica, Part I, under "General summary . " Because of their unusual physical properties tripoli and diatomite find extremely wide uses in industry, and as the commercial deposits of these ninerals , especially tripoli , are scattered, large quantities enter into interstate commerce . Whereas ordinary sand and gravel are bulky commodities , these specialties have a fairly high unit value and hence can be transported relatively long distances .

Aug 1, 1931

Jan 1, 1886

By David van Cleave, David L. Rome

Whether you buy your minicomputer from a manufacturer or another vendor, the first thing you must do is define your needs. With good planning, the initial cost will be low and your return on investment will be maximized over the long term. Involving all members of your staff who will he using the new computer in the planning phase is also important. Their participation will alleviate any potential concerns they may have about new equipment, and their suggestions will provide valuable input for your specifications. After you define your proposed system, survey available hardware and software. The survey will help you in the next step, preparation of specifications. The specifications, along with a quote request, are then sent to various manufacturers. Consider the Manufacturer When selecting your minicomputer, one important item to consider is the manufacturer. Remember, when you buy a computer, you're also buying the services of a computer company. A firm that makes a commitment to its customers and provides a product that is field tested before releasing it for sale is preferable. Examine the company's maintenance and support packages, since every machine requires preventive maintenance. Does your manufacturer or original equipment manufacturer (OEM) support service sites in your area? Has their service record been commendable? Will they provide training for your personnel and a supply of circuit boards so you can retain a degree of self-service autonomy? Three methods of buying a computer involve the manufacturer, an OEM, and the systems house. Buying direct from the manufacturer means you go straight to the source, using no middleman. This gives you maximum flexibility; you can consider every alternative and many possible combinations of computers, peripherals, and software until you find exactly the right system for you. The OEM buys computers direct from the manufacturer and builds them into his own computerized, special purpose product. He usually sells a complete package, including software and hardware, and often noncompetitive equipment as well (a scientific or engineering instrument, for example), designed for the mining market. Because he offers a packaged product, the OEM can often charge less for the system than if you put the pieces together yourself. In many ways, the OEM also provides a unique system. And while the OEM sells a packaged solution, he also usually has the special market knowledge necessary to modify the system to meet your unique needs, if necessary.

Jan 11, 1981

By Yi Luo

In dealing with various subsidence cases, accurate predictions of mining induced subsidence are the basis for correct assessment of subsidence influences and subsequent mitigation efforts. There is a good demand for a reliable tool to perform the subsidence predictions and related tasks. A comprehensive and integrated subsidence prediction model, CISPM, developed by the senior authors in the later 1980?s and early 1990?s (Peng and Luo, 1992) is one of such tools. Built on solid mathematical models and calibrated by a large number of collected subsidence cases, CISPM provides a rich set of features needed in subsidence engineering and research works. Its reliability and usefulness have been proven by numerous field applications. This upgrade of CISPM will not only preserve its original features and reliability but also provide some new needed features and a more user-friendly working environment.

Jan 1, 2008

Inn mining communities throughout the western United States, cows have always been part of the landscape as they graze on surrounding rangelands. Until recently, mining companies regarded these animals as something to be kept off their properties — especially any freshly reclaimed lands. During the last few years, though, this situation has begun to change. Today, cattle can be seen in a handful of mine settings, moving up and down the slopes of mine tailings and waste rock. These animals are being used by several companies to do some of the reclamation work once performed by large earth-moving equipment, mechanical spreaders, rippers and seed drillers. This is because cows can contour slopes more naturally and produce and spread soil nutrients in ways that tractors and ripping machines cannot.

Jan 1, 1999

By F. Vasilikou

Commercial deployment of Carbon Capture Utilization and Storage (CCUS) requires field testing of a scale that can stress the geologic reservoirs. One such reservoir of interest consists of unminable coal seams that exhibit favorable characteristics and depositional environments and lower pressure and temperature than other, deeper, reservoirs. Such conditions can reduce compression costs while utilizing the action of adsorption that offers a more effective carbon dioxide (CO2) bonding than free storage or solution. To ensure the success of such tests, a number of parameters should be accurately determined, such as the seam geometry and stratigraphy, coal porosity and permeability parameters as well as optimum injection conditions. In essence the CO2 injection model should be calibrated for the reservoir characteristics using all available data. History matching calibrations are based on gas and water production from existing wells prior to injection. This paper will present reservoir models that were developed for a pilot--scale 907 tonnes (1000 tons) CO2 injection test that was performed in 2009 through one legacy coalbed methane production well in Russell County, Virginia, USA. The model incorporates a number of individual coal seams about 0.3 m (1ft) in thickness located at depths ranging from 300 to 700 m (1,000 to 2,200 feet). Model calibration was performed through history matching to prior production data, and subsequently the model was utilized to develop different injection scenarios. The developed model was used after injection to calculate CO2 plume distribution patterns that were monitored at the injection test. The paper will present model data and assumptions with a special emphasis on the effect of hydraulic fractures and the skin factor to the coalbed methane (CBM) production model.

Aug 1, 2013

By P. C. Hodges

WHILE there is very little romance connected with the operation of a stone quarry, yet to those who have participated in the growth and development of a business that has been a pioneer in its field and that FIG. 1.-LOCATION OF PROPERTY OF MARBLE CLIFF QUARRIES COMPANY. has been in continual operation two-thirds of a century there is bound to be a background of experience, which if properly capitalized, brings progress as well as satisfaction in its accomplishment.

Jan 1, 1936

By S. McGinn

The Brunswick Mine Diesel Particulate Filter Study was one of several research projects initiated by the Diesel Emissions Evaluation Program (DEEP). The study was carried out at Noranda?s Brunswick Mine in Bathurst, New Brunswick by Noranda Technology Centre and Brunswick Mine personnel with the collaboration of Natural Resources Canada - Canada Centre for Minerals and Energy Technology (CANMET), National Institute of Occupational Safety and Health (NIOSH), Andreas Mayer of VERT, and diesel particulate filter (DPF) system suppliers. The study began in early 2000. Field evaluations continued for 20 months. The final report?authored by Sean McGinn?was submitted to DEEP in the Autumn of 2003.

Jan 1, 2004