Search Documents

Triboelectrostatic Producing Ultra-Clean Coal

Sep 13, 2010

By J. Nell

An overview is given of the matte melting process used for the beneficiation of South African Platinum Group Metal (PGM) ores. Most producers use six-electrode furnaces to melt the concentrate and Pierce Smith converters to oxidize excess iron sulphide from the furnace matte. Concentrates from two reef-types (the so-called Merensky and UG-2 reefs) dominate the feedstock supply. Concentrate from the Merensky reef is low in chromium and do not pose significant melting problems. Concentrates from the UG-2 reef contain much higher levels of chromium, which results in the formation of chromium-rich spinels during melting. This is attributed to the low solubility of chromium in furnace slag under typical operating conditions (an oxygen partial pressure of 10-8-10-9bar at temperatures of 1550°C to 1600°C). During the converting process care is needed to avoid excessively oxidizing conditions, which result in cobalt, nickel and copper losses to the slag. High nickel losses result in the formation ofFe2NiO4(trevorite), which often forms solid solutions with FeCr2O4and Fe3O4. In future, the main challenge in the processing of South African PGM ores will be to cope with ever increasing levels of chromium in the concentrate. A short-term solution to the problem would be to melt the concentrate under slightly reducing conditions to promote the formation of CrO, which is more soluble in the slag than Cr2O3. A longer-term solution to the problem would be to abandon the current matte-smelting process in favour of an alloy-based process, which would offer total flexibility with respect to the amount of chromium that can be tolerated in the feed. Key words: Merensky, UG-2, furnace, slag, matte, converting, spinel, chromium.

Jan 1, 2004

By Steven Townend

Mining-related activities have been known to create a challenging operating environment for mining companies located in close proximity to communities. Issues such as noise, vibrations from mining operations, land use and emissions are often a concern for community residents. In order to develop good community relationships it is necessary to take a proactive approach. This paper documents this approach and also deals with the social implications for Vale associated with mining activities in the heart of the community of Copper Cliff, Ontario, Canada.

May 1, 2011

By D. E. Pollock, T. W. Beck, J. A. Organiscak

This work presents the findings from a number of NIOSH studies evaluating the impacts of emerging technologies that may reduce dust exposures for continuous mining and roof bolting personnel. These technologies include use of a wet head cutting drum on a continuous mining machine that places water sprays on the cutting drum instead of placing them on a manifold outby the drum. Evaluations at two separate operations showed that the use of the wet head sprays reduced dust levels at the miner operator in the return air, although these reductions were quite variable. NIOSH also assessed the effectiveness of a canopy air curtain for protecting roof bolting personnel. The data showed that dust levels were lower beneath the air curtain than outside the air curtain. This study also suggested several future modifications to the air curtain to in-crease its effectiveness. Finally, NIOSH evaluated mist drilling technology for its effectiveness in controlling respirable dust exposures of bolting personnel. A recent study showed that higher dust levels existed around a machine using the mist system compared to a machine using a conventional vacuum system for dust control. Unfortunately, the true impact of mist drilling was confounded by this machine operating downwind of the continuous miner for much of the study.

By L. Munsamy, B. J. Madden

OpenRisk, an open cast risk rating system, takes into account relative differences in the importance of hazards, as experienced on each mine as a result of different combinations of geotechnical factors and mining conditions. The system is based on critical geotechnical and operational parameters that have been identified by mining personnel and rock engineers. The primary advantage of this risk rating system is that all the strip mines would use an identical system, which enables the user to compare their risk to the risk at neighbouring mines and/or other open cast mines. The system can be adjusted to meet local, mine specific requirements. This system has been made practical and easy to use. Therefore, this tool can be used by personnel from other disciplines not directly related to rock engineering. OpenRisk system has been in operation at nine Anglo Coal and other open cast mines. It adequately detects areas of high risk and generates adequate remedial solutions to reduce the risks. Awareness of the personnel has been higher at the sites that use OpenRisk. The proactive approach of OpenRisk ensures that all personnel are aware of risks in the pits and how to deal with potential risky areas.

Jan 1, 2006

By Russell Carter, Tom Barkley

"Optimization of blasting is hampered by the lack of inexpensive methods of measuringblast results. Optical methods of size analysis have the potential of creating abreakthrough in size analysis and in overall blast optimization. Attainment of reliablemeasurements hinge on solving a number of shortcomings inherent to optical systems."

Jan 1, 1999

By M. Shahabi, M. Kashfi

This paper briefly describes the excavation procedure of a powerhouse, comprising of its incremental excavation, reinforcement measures, and the installed monitoring system. During the first phase of excavation, the data obtained from monitoring of the behavior of Mudstone layers were used to recommend extra support measures. These data are also used to design the support of the powerhouse during its extension phase. In diesen bericht wird die bohrmcthode von kraftwerk ecavation in stupenweise dargestelt, und in die richtung d.sicherung, Mit hilfe von monitoring systeme. Die monitoring in (mudstone) schichten ist an schutz in bohrung entworfen und montiert in diese methode in K.W. fase 1 schutzung das K.W. in erweiterung der K.W. das berte auserwelt worden ist Cet article décrit brièvement le procédé d'excavation d'une centrale électrique, comportant de son excavation incrémental, de mesures de renfort, et du système de surveillance installé. Pendant la première phase de l'excavation, les données obtenues à partir de la surveillance du comportement des couches de schiste ont été utilisées pour recommander des mesures supplémentaires de soutien. Ces données sont également utilisées pour la conception de la soutènement de la centrale électrique pendant sa phase d’extension.

Jan 1, 2003

By R. J. McLeod

"CONTROL STRATEGYThe Lake Dufault Division of Falconbridge Copper Limited has been concentrating a complex copper zinc ore since late 1964. An ARL X-ray on stream analyzer was installed in 1966 for process control. A Digital Equip-ment Corporation PDP8 was added in 1968 for more complete control. To improve the system the computer was exchanged for a Moded PDP-81 in 1971.The new computer is time sharing with 8K core memory and 32K disc storage. A new interface was installed to accommodate 14 X-ray streams and additional analog signals for process control. The system gave us additional capacity and flexibility to make changes in operating programs and control strategy while on line. As the computer is used for process control a modified focal language was chosen as the operating language for ease of operation. This language is more suitable for process control than for statistical work.The main components of the control system are(a) Computer(b) Interface(c) Production Control X-ray Quantometer(d) Teletype terminals(e)Reagent feeders(f) Sample SystemThe operation of the system consists in the computer selecting the various streams to be analyzed by a PCXQ Quantometer. When the flowing sample is presented to the X-ray the intensities of the various elements are read by the computer from analog to digital converter, the assays are then computed. From the tonnage and assays the computer is programmed to determine the amount of reagent added to various parts of the circuit. The computer drives the feeders via the interface for the required amount of reagent. After following a certain sequence the computer prints out the performance and control data on an ASR35 Teletype. The data is printed out approximately every seven minutes. Any des¬ired changes in the program or strategy can be made during operation via an ASR33 Teletype connected to the computer."

Jan 1, 1973

By K. Hoover, G. Labarre, S. Rantanen

"As part of the Namew Lake project a mill was constructed to treat 1900 tpd of ore grading approximately 0.90% CU and 2.45% Ni to produce copper and nickel concentrates.Nickel occurs mainly as pentlandite and violarite while copper occurs as chalcopyrite. Two main ore types are present1 lower grade disseminated sulphides in a talcose ultramafic gangue and a higher grade solid sulfide with a granitic breccia matrix.Primary crushed ore from underground is treated on surface in a conventional closed circuit crushing plant using 2-stage cone crushing. Crushed ore is conveyed to storage and then fed at a controlled rate to a grinding circuit employing a rod and ball mill with hydrocyclone classification. Rougher flotation separates and cleans nickel and copper sulfides from waste materials followed by a high lime separation circuit to separate the minerals into final concentrates. Dewatering is achieved through use of high capacity thickeners and pressure filters prior to delivery to a loadout area. The crushing and milling control is highly automated.Plant design was based on metallurgical samples obtained from drill cores. After the first year of operations, plant results compared favourably with design projections.INTRODUCTIONThe Namew Lake Project is a joint venture partnership between Outokumpu Mines Ltd. (Canada) and Hudson Bay Mining and Smelting Company Ltd. (60%). The project included construction of a mine and milling complex to treat approximately 500,000 tonnes per year of copper-nickel ore grading o.91% and 2.44% Ni. Known reserves are estimated at 2. 65 million tonnes. The deposit is located approximately 65 km south of Flin Flon (120 km by road) and about 5 km east of the Manitoba-Saskatchewan border. The decision to construct a concentrating facility was made June 15, 1987 and construction started a week later. The facility, designed for 1900 tonne per day throughput, was ready for commissioning in September 1988. Outokumpu Engineering of Finland was chosen to prepare metallurgical flowsheets, select and develop plant layouts, and provide construction management. Kilborn (Toronto) contributed detailed engineering for civil, structural, mechanical and electrical components and outokumpu Equipment of Canada, the design, the supply, and commissioning of the instrumentation package. Hudson Bay undertook the initial metallurgical test work and preliminary design work."

Jan 1, 1990

By K. S. Rao, R. P. Tiwari, V. K. Shrivastava

ABSRACT: In this paper numerical simulation of jointed block mass behaviour obtained in an experimental study has been presented. Singh et al. (2002) conducted extensive tests on the jointed model materials with several joint configurations. The results of this experimental study were used to validate the strength behaviour of numerical block mass model developed using professionally available software. This software basically contains different kinds of material models. From the results of numerical simulation the existence of strength anisotropy was observed. The strength anisotropy so obtained has been compared with the experimental values reported by Singh et al. (2002). The anisotropic curves in both cases are U-shaped with flat base. They show good agreement in sliding mode of failure zone in which inclination ß (= 90° - ?) of joint set-I lie between 20° to 40° for all cases of interlocking. ZUSAMMENFASSUNG: In dieser numerischen Papiersimulation des verbundenen Blockmasse Verhaltens, das in einer experimentellen Studie erhalten wird, ist dargestellt worden. Singh et al. (2002) leiteten umfangreiche Tests auf den verbundenen vorbildlichen Materialien mit einigen gemeinsamen Konfigurationen. Die Resultate dieser experimentellen Studie wurden verwendet, um das Stärke Verhalten des numerischen Blockmasse Modells zu validieren, das mit professionell vorhandener Software entwickelt wurde. Diese Software enthält im Allgemeinen unterschiedliche Arten der materiellen Modelle. Von den Resultaten der numerischen Simulation wurde das Bestehen von Stärke Anisotrophie beobachtet. Die Stärke Anisotrophie also erreicht ist mit den experimentellen Werten verglichen worden, die von Singh et al. (2002) berichtet werden. Die anisotropen Kurven in beiden Fällen sind mit flacher Unterseite u-förmig. Sie zeigen gute Vereinbarung in gleitender Erscheinungsform des Ausfalls Zone, in der Neigung ß (= 90° - ?) von der Verbindung stellenSie Lüge zwischen 20° auf 40° für alle Fälle vom Ineinandergreifen ein. RESUME: Dans cette simulation numérique de papier du comportement joint de la masse de bloc obtenu en étude expérimentale a été présenté. Singh et autres (2002) ont effectué les essais étendus sur les matériaux modèles joints avec plusieurs configurations communes. Les résultats de cette étude expérimentale ont été employés pour valider le comportement de résistance du modèle numérique de la masse de bloc développé en utilisant le logiciel professionnellement disponible. Ce logiciel contient fondamentalement différents genres de modèles matériels. Des résultats de la simulation numérique on a observé l'existence de l'anisotropie de force. L'anisotropie de force ainsi obtenu a été comparée aux valeurs expérimentales rapportées par Singh et autres (2002). Les courbes anisotropes dans les deux cas sont en U avec la base plate. Elles montrent la bonne concordance dans le mode coulissant de la zone d'échec en lequel la inclination ß (= 90° - ?) du joint placez-Je le mensonge entre 20° à 40° pour tous les cas d'enclencher.

Jan 1, 2003

By E. C. Westman, F. J. Shreve

This paper presents the design and construction of a multi-channel geophone array that improves tomographic imaging capabilities in both surface and underground mines. Especially important in the design of the array is sensor placement. Three issues related to sensor placement are addressed in this paper: 1) sensor placement in long, horizontal boreholes, 2) development of simple, robust, MSHA-acceptable clamping unit, and 3) orientation of the geophones within the borehole. Improved imaging capabilities will produce energy, environmental, and economic benefits by increasing exploration accuracy and reducing operating costs.

Jan 1, 2002

"Increasing demand for timely and accurate information about flotation plant performance requires metal accountants to increase the scope and reporting frequency of plant production. This trend has brought in-process inventory estimation at the forefront of metal accounting issues. Such significant in-process inventories can be locked in diverse process equipment (bins, holding tanks, flotation cells, thickeners, pipeline, etc.) or in stockpiles (ore, concentrates, tailings, etc.). Practice has shown that boldly ignoring these in-process inventories or the errors associated with their estimation lead to unreliable metal balances thereby creating confusion in plant production planning and operational performance assessment. To this extent, the characteristics (physical bounds, spatial heterogeneity and residence time) as well as the available measurements (volume, density, humidity, mass, composition, etc.) of each unit/section found in a generic flotation plant are jointly reviewed with respect to the particular metal accounting issues they present. The daily and monthly metal accounting tasks are then reviewed together with possible methods for obtaining reliable inventory estimates including different procedures for end-of month reconciliation.INTRODUCTION Most of the cost reduction initiatives of the mining industry aim at improving capital efficiency and asset utilization. Among the possible paths through which these goals can be achieved are mine-to-metal optimization, real-time plantwide process control (Hodouin, 2011) and knowledge sharing databases (Bascur & Linares, 2006). However, the successful implementation and subsequent monitoring will ineluctably results in an increased demand for timely and accurate information. This more than often requires metal accountants to increase the scope and reporting frequency of plant metal production. A striking example of such scope expansion is the Minas-Rio iron ore project in Brazil (Anglo American, 2013) having a pipeline route of 525 km between the concentrator and the concentrate shipping area. Several other mining companies have also set an increased frequency for their key performance indicators thereby shrinking the metal accounting period from monthly to weekly and daily. Those concurrent trends have brought in-process inventory estimation at the forefront of metal accounting issues. Indeed, as illustrated in Figure 1, improving trading reactivity requires improvements in production planning which strongly impacts the requirements for reliable metallurgical accounting. Furthermore, practice has shown that boldly ignoring significant in-process inventories or the errors associated with their estimation can lead to unreliable metal balances. In other words, since metal balances are the cornerstones of metal accounting, some of the risks associated with important business decisions are linked to errors associated with in-process inventory measurements."

Jan 1, 2014

By H. D. Stolovitch, M. L. Lavallée

"An engineering system used to analyze and improve the performance of industrial grinding circuits has been adapted into a training program. The systematic approach to the design of training was applied in order to:Determine if training was an appropriate and effective tool for the transfer of this new technology;Define the technical content of the program;Establish program specifications based on learner and context characteristics;Design and test prototypes of the instructional modules; and,Establish a strategy for plant implementation and maintenance of the training program.This paper thus describes how a engineering system is transferred to the workplace through the use of designed instruction.INTRODUCTIONTraining can change human performance in a permanent way. It can improve productivity for the overall benefit of an operation. Organizations can therefore use training as a mean to achieve their specific goals. Training is not the solution to every performance problem. However, in many cases, it can be a very effective way to attain desired performance.The benefits of training are often difficult to assess. However, to remain competitive, organizations must introduce new products and innovative technologies. Often, they can do both most effectively through suitable training interventions.In order for the effort and investment of training to provide optimal results, two points of view should be adopted.• An overall view of the system in which training is to be applied.• A systematic approach to the design of training (Stolovitch and Keeps, 1989)."

Jan 1, 1992

By W. Blum

Progress made in improving the creep resistance of Mg alloys is reviewed with the emphasis on microstructural interpretation. Experimental results on the increase of creep strain with time at constant stress a measured for limited times and strains are displayed in a transparent form as creep rate-strain diagrams from which the minimum creep rate stress is safely derived. In addition, data on the thermal stress component a derived from high-precision a-reduction tests are reported. Within a simple statistical dislocation model these data allow one to quantify the relation between dislocation velocity v and a . In combination with structure evolution laws this relation serves as a basis for modeling the creep rate. New alloys have distinctly higher creep resistance than AZ91 where precipitation hardening plays a minor role. This is due to hardening by intermetallic phases which may form a continuous skeleton along the grain boundaries (e.g. Ca-alloyed AZ91) and/or submicron-sized precipitates within the grains (MRI230D, Mg-Zn-Ca alloys).

Jan 1, 2006

By D. R. Babich, E. R. Bauer

National Institute for Occupational Safety and Health (NIOSH) researchers are conducting a cross-sectional survey of equipment noise and worker noise exposures in the mining industry. Surface and underground limestone is one commodity recently surveyed. The sound levels of mining and processing equipment were recorded to identify noise sources. Full-shift worker noise exposures were completed to determine the exposure of various occupations. This paper presents the results of the noise research conducted in both underground and surface limestone mines, detailing the equipment likely to cause worker overexposures, and the occupations experiencing overexposures. Implications for worker noise exposure reduction are also reported.

By Todd Wanless

This paper addresses the challenges experienced by the designer and three government agencies during implementation of major improvements for the Turkey Creek Tunnel in Kansas City, Kansas. The tunnel serves as a vital stormwater conveyance system for upstream flood control. Major structural deficiencies were identified within the tunnel including complete loss of sidewall and invert. Without immediate attention, complete loss of the tunnel arch could lead to blockage and extensive remedial repairs under difficult conditions. Considering that tunnel flows must be maintained during construction, a phased design and construction process has been implemented to expedite stabilization of the erosion cavities followed by tunnel liner repairs.

Jan 1, 2008

By T. G. Madgwick, A. Beeby Thompson

FoR more than 2500 years, natural gas issues in the Surakhany district of the Apsheron peninsula were the object of pilgrimages by fire worshippere and Hindoos from Burma and India. Even as late as 1890, Hindoo priests conducted ceremonies in a temple at Surakhany, which probably replaced a more ancient one; but later, the visits of the pilgrims were prohibited in order to check the spread of Asiatic diseases in that region. For centuries, limited supplies of oil have been abstracted from shallow excavations in the Caspian oil belt and dispatched into the interior of Asia and elsewhere for medicinal and industrial purposes. Statistics show a yield of 37,400 bbl. in 1863, but only since 1869 has there been serious development; in that year the yield was 203,000 bbl. At that time, hand digging was supplanted by drilling, and the enormous wells that resulted from tapping sources hitherto beyond the reach of operators completely demoralized the industry for a time, owing to inadequate outlets for the products. The early activities in this area were greatly hindered by annoying taxation, monopolies, imperial land grants, etc., but when these were revoked or adjusted, in 1877, the industry sprang into prominence and, between 1898 and 1901, the Baku fields produced practically one-half of the world's supply of oil. Within a few miles of Baku lie the two richest oil fields in the world; viz., the Balakhany-Saboontchy-Romany and the Bibi-Eibat, the latter constituting almost a suburb of the city. For many years the gasoline obtained in the refineries of the Baku area was burned in pits, being considered an undesirable product, and until 1870 the residue also was destroyed, its value as a fuel not being recognized. Kerosene was the main product sought by the refiners. It was shipped across the Caspian Sea and up the Volga to the industrial centers of Russia. Only on the completion of the Baku-Batoum railway did the Baku oil fields secure important commercial communication with the outside world through the medium of the Black Sea. The first tank steamer was successfully launched on the Caspian in 1879, by Messrs. Nobels, for transporting oil in bulk instead of in barrels. In 1905, an 8-in. pipe line to Batoum was completed; this was capable of transporting to seaboard 8,000,000 bbl. of kerosene per annum.

Jan 1, 1921

By Frederic Vanderoost

Actualmente, el manejo adecuado de las informaciones geológicas en el sector minero optimiza recursos y maximiza resultados. En ese sentido, el presente texto señala la implantación de un conjunto de herramientas para la administración de banco de datos geológicos, de forma corporativa y manteniendo un informe central de datos. Dichas herramientas se basan en sistemas comerciales de base de datos como Oracle, Microsoft SQL Server y Sybase, los cuales garantizan agilidad, flexibilidad y capacidad de almacenamiento para el manejo de informaciones adecuadas y las operaciones típicas de la industria minera. Asimismo, se presenta estudios de casos, analizando sus ventajas, limitaciones y dificultades encontradas en una mina.

Aug 25, 2002

Discussion of the paper of Robert Henry Lee, presented at the New York Meeting, October, 1913, and printed in Bulletin No. 82, October, 1913, pp. 2515 to 2522. J. E. JOHNSON, JR., New York, N. Y.:-This subject is of great and increasing importance, as the exhaustion of the deposits of ore of ideal character compels the iron industry to turn more and more to those which are less desirable on account of physical structure as well as analysis. Thus there has come about the use of the Mesabi ores in this country and also of the Minette ores in Europe, which produce far greater percentages of flue dust than did the lumpy ores first used. It is a matter of common knowledge that the utilization of this flue dust, containing commonly 50 per. cent. or more of metallic iron, has been a problem very difficult and tedious of solution. The number and variety of the solutions now offered is a sufficient proof of this. . I have no intention of going into the merits or demerits of any of these processes as such, but there are certain considerations concerning the effect of their product on the operation and fuel economy of the blast furnace which I believe to be new and which I desire to bring out. There are two methods, so different as almost to be direct opposites of each other, whereby an ore may exercise an unfavorable effect on the economy of the blast furnace. The first of these is well known and results from the ore being refractory and highly resistant to the action of the reducing gases of the blast furnace. This results in its being incompletely reduced when it reaches the zone of fusion and in the reduction being finished by the direct action of carbon in the lower portion of the furnace. This is so well understood as to need little elaboration or comment. There is, however, another action which may be equally as fatal to the economy of the furnace as the foregoing, and as this point is, to the best of my knowledge, not generally appreciated, it is one upon which I desire to lay particular stress. This consists in the ore being, in a sense, too reducible.

Jan 12, 1913

By Pratoomkhuan N. Lertsgoon

A large underground cavern with dimensions of 25m × 175m × 49m (W×L×H) was excavated in sandstone and siltstone to house 4 units of hydropower generator and was completed in 2000. In feasibility study stage, the property of the siltstone which governs the ceiling of the cavern was questionable due to slaking phenomenon. Parameters on rock properties for design were back calculated from actual ground response measured from a trial excavation. For safety of construction, comparison between prediction and actual ground responses during excavation had proceeded. The prediction was provided by means of PHASES and PHASE2 software and the actual rock response was detected by the provided monitoring system.

Jan 1, 2003