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Lime-enhanced carbothermic reduction may provide an alternative process for treating low grade chalcopyrite concentrates. To date, most research on lime-enhanced reduction has been on pure, synthetic sulfides. In this study, preliminary experiments were carried out on natural chalcopyrite using a thermal analysis system to assess the rate and extent of reaction at several temperatures and identify the major solid and gaseous reaction products. Calculations were performed to establish the thermodynamic limits of the reactions in the temperature range of interest in order to identify the potential conditions for processing chalcopyrite concentrate. The study found that finely ground chalcopyrite can be reduced carbothermically in the presence of lime at moderate temperatures and in a reasonable time to form metallic copper, with the sulphur reporting virtually entirely to calcium sulfide. At temperatures below about 750?770ºC calcium ferrite is the stable form of iron whereas at higher temperatures metallic iron is stable. Further work is required to demonstrate the reaction on a scale to obtain sufficient sample for evaluation of subsequent processing steps to remove the gangue material and iron products from the copper.

Jan 1, 2009

By Dennis Dolinar

Improperly designed support systems have led to unplanned roof falls in longwall tailgates. To prevent such falls requires appropriate support and adequately designed support systems. The National Institute for Occupational Safety and Health (NIOSH) is currently developing a standing support design methodology based on the ground reaction curve. To design the support system with this methodology requires a quantitative assessment of the ground and support interaction, which is developed from instrumented test sites installed in longwall tailgates. To compliment and expand the field data results and to optimize the support design, numerical modeling is also conducted. The models are calibrated from the test site data. In the present study, data was obtained from a longwall tailgate in the Illinois basin. The test site was located in the Herrin No. 6 coal seam at a depth of 500 ft. At the site, the immediate roof was a weak shale overlain by a competent limestone. Above the limestone, sandstone formed the intermediate roof. The floor consisted of a weak underclay. In the study, the performance and interaction with the surrounding rock mass of two different standing supports, an engineered crib and a conventional 4-point wood crib were monitored. The two cribs have similar load-displacement characteristics at least through 6 in of displacement. Beyond 6 in, the engineered crib becomes unstable and begins to strain soften and shed load. The measurements and developed ground reaction curves indicated that the tailgate at the mine was a low convergence environment until well inby the face. Because the convergence was well below their capacity, both supports provide more than adequate levels of support to the tailgate. Significant convergence and support loading did not occur until 90 to 100 ft inby the face. The results of this study were also compared with results from similar studies conducted in the Pittsburgh seam to further advance the development of the ?ground reaction curve? based support system design.

Jan 1, 2009

By Dennis Ofiara, Michael Lewis

An experimental 1.75 meter Shaft Boring Machine was designed and manufactured by The Robbins Company. The drill was used by contractor Drillcon Raise AB to drill test shafts at an SKB underground test facility. SKB is the Swedish authority responsible for safe management of nuclear waste materials. This “SBM1.8” Shaft Boring Machine was used to drill shallow test shafts ingranitic rock at SKB’s Aspo underground laboratory. The drill used a unique vacuum mucking system. The bored shafts were held to very strict tolerances for bore diameter, straightness, and verticality. This drill was launched and operated from a mobile launcher. Headroom and working space were limited. The SBM1.8 drill produced acceptable test holes. SKB will carry out several studies to determine the suitability of this geology, and of this technique, for safe nuclear disposal. In addition to future use at SKB, many applications are foreseen, particularly in the civil construction industry.

Jan 1, 2005

By Ilpo O. Auranen

Background: Mines of today are moving ever increasing tonnages of rock. The new ore bodies tend be of lower grade and located deeper in the earth?s crust. The industry?s focus to overcome this ?deeper but poorer? ore problem has traditionally been to lower the costs by increasing the scale of mining. This has resulted in an ever increasing size of mining equipment like drills, loading shovels, dump trucks. The main focus has been in reducing the cost per ton of mining. This cost focus has often resulted in increased waste rock dilution and more ore losses. From costs to value: Waste rock dilution means waste rock in the concentrator feed. It?s value in open pit mining is equal to the value of ore it replaces. In underground mining, waste rock dilution?s value is equal to the value of ore it replaces added to the costs of mining it. It is commonly accepted that waste rock dilution in open pit mining ranges between 5 and 20% and in underground mining between 5 and 40 % . In a typical large open pit mine ore value is from 20 to 60 USD per ton and mining costs are 1 to 3 USD per ton. One percentage point reduction in waste rock dilution represents savings corresponding to about 20% of total mining operation costs. The difficulty of reducing waste rock dilution comes from the complicated nature of the ores. Accurate ore waste-border detection has not been possible due to excessive costs. Core drilling combined with geochemical lab analysis is the most accurate method for locating ore waste borders. However, it is also expensive and time consuming, which is why it is often combined with somewhat lower cost methods like sampling drill cuttings from blasting drill holes or from reverse circulation drills and analyzing them in a laboratory. The main drawback with these methods, in addition high costs, lies in the sampling accuracy and in the quality control of the whole process when a large number of samples have to be handled manually. In every mine it is possible to halve waste rock dilution by using new on-line analysis technology .

Oct 1, 2009

By David A. Monaghan

On January 14, 1974 a fire occurred in the 3 East mains of the Joanne Mine of Eastern Associated Coal Corp. in Rachel, West Virginia. The mine was evacuated without injury and sealed completely at the surface within 24 hours. It was decided by the coal company along with the U, S, Bureau of Mines, the West Virginia Bureau of Mints and MESA that remote sealing of the fire zone would be attempted. This report summarizes the remote sealing effort and those activities directly related to the remote sealing effort. This chapter provides a brief history of previous remote sealing attempts, a description of the recently developed remote sealing system and a description of the Joanne Mine operation as it related to and affected the remote sealing effort.

Jan 1, 1975

By Jorge Díaz A

El presente texto revisa los métodos utilizados en las minas de tajo de abierto como son la perforación, disparo y seguridad y así mejorar los standars y el rendimiento futuro en la industria minera. Respecto al primer método empleado, se analizan los factores que afectan el rendimiento de brocas y cómo dicho factores varían, impidiendo la adaptación de prácticas universales de perforación. Asu vez, estos mismos permiten seleccionar el tipo de broca adecuado y mejorar el máximo rendimiento del mismo. En cuanto la voladura y los explosivos, se revisan las variables fundamentales que ejercen una influencia sobre el resultado de un disparo y así realizar un estudio comparativo de los agentes explosivos en uso, tratando de interpretar el mecanismo de la explosión y a la vez aplicarlo a las diferentes formaciones presentes en Cerro. Finalmente, se describe la organización del sistema de seguridad y las obligaciones de este comité en la industria minera.

Aug 20, 1965

By D. J. Turk

Stillwater Mining Company’s, Nye Operation has been producing PGM concentrate since 1987.Several expansions have allowed for increasing capacity from the initial rate of 500 tons per day, to its present capacity of 3,000 tons per day. The expansions were performed with minimal impact upon production and maximum utilization of the existing equipment. The latest expansion incorporates a 6’ X 18’ SAG mill, 13’ X 20’ Ball mill, pebble crusher, rougher flotation cells, 1250 Hp tertiary grinding mill, middling and scavenger flotation cells, and cleaner column flotation cells. This paper will describe the concentrator flow sheet, and controls for improved concentrator performance.

Jan 1, 2000

By P. D. R. Maltby

"With the narrow vein structure of Nova Scotia gold deposits, selective mining is rarely possible and mill heads will be too low (below 0.10 oz per ton of gold) to support a conventional mill of up to 1000 ton per day capacity at present gold prices. The recent operation of a small 100 t.p.d. mill at Cochrane Hill using fine grinding - leaching - filtration supported this assertion. Milling costs exceeded $25.00/ton of feed mainly due to high capital, labour and maintenance costs.Accordingly, since 1981, efforts have been directed towards the development of a cheap gold extraction process in terms of both capital and operating costs. The main criteria is to produce gold below US $200 per oz including all administration, mining and process stages. This paper describes such a process development for Cochrane Hill. LOCATION AND HISTORY OF THE PROPERTYThe Cochrane Hill property is located about 8 miles North of Sherbrooke, N.S. on highway No. 7. Sherbrooke is about 180 miles east of Halifax. Gold was originally discovered at Cochrane Hill in the 1860's. Early work consisted of trenching. In the 1930's a small shaft was sunk to about 80 feet and some tonnage treated using a stamp mill with gravity concentration of gold.Northumberland Mines Ltd. acquired a 70% interest in the property in 1977. Subsequent drilling indicated a potential zone of gold mineralization with a drill-indicated tonnage of one million tons having a grade of 0.07 ounces per ton of gold (all high assays cut to 1 oz) down to a depth of 300 feet recoverable by open pit mining methods. In broad terms, the goldbearing zone is about 50 feet wide and 800 feet long and dips at about 70°."

Jan 1, 1984

By F. D. Ford, Z. Dai

"Vale’s Ontario Operations re-introduced Cu/Ni separation at Clarabelle Mill in 2006. The mill processes ores from a number of mines in the Sudbury basin. A saleable Cu concentrate is produced at 30-60% Cu recovery from mill feed, which has to meet the quality specification. In particular, Ni content in Cu concentrate must be less than 0.6%, otherwise, penalties will apply and diminish the value of Cu concentrate, in addition to the lost Ni value. Generally, a Ni grade of less than 0.4% is obtained in Cu concentrate. More recently, while processing Cu-rich ore, Cu concentrate contained more than 0.6% Ni which is abnormally high. Detailed mineralogical investigation shows that Cu-rich ore contains more millerite in comparison to typical Sudbury Ni sulphide ore. Millerite is found to be more floatable than pentlandite and is much more difficult to depress using high-lime aeration conditioning, which is the standard practice in Cu/Ni separation to float chalcopyrite while depressing pentlandite. The current operation uses sodium cyanide at 20 g/t to depress pentlandite and pyrrhotite. However, it is found that a high dosage is required to depress millerite. It is also shown that starch and dextrin are promising in millerite depression.INTRODUCTIONPrior to bulk smelting in 1991, Cu/Ni separation was carried out at Vale’s Copper Cliff Mill, Ontario Operation. The typical Cu concentrate grade was around 30% Cu and 1% Ni. This is very high in comparison to today’s value of 0.4% Ni and would not be acceptable for external processing. However, the Cu concentrate was processed internally at the Copper Cliff smelter/refinery, so the Ni contained in Cu concentrate was not lost and no actual penalties applied. During the SO2 abatement initiative, bulk smelting was chosen because of the perceived simplicity and consequently, Cu/Ni separation was eliminated (Agar, 1991) and the Copper Cliff mill was subsequently demolished. In 2005 and after more than one decade of bulk smelting, business changes required the removal of some Cu concentrate from Clarabelle Mill bulk concentrate to provide smelter capacity for Voisey’s Bay concentrate in the Copper Cliff smelter. In essence, this strategy calls for Cu removal at Clarabelle Mill (Lawson, 2006). In this case, Cu concentrate is sold externally and it must meet the quality requirement of less than 0.6% Ni."

Jan 1, 2011

By T. J. Ballard

"INTRODUCTION The Buck. Creek corundum area of Clay County, North Carolina, includes one of the largest single masses of peridotite outcrops in the whole Appalachian Range and has been described by Pratt, an early authority on corundum, as offering one of the best potentialities for corundum production in North Carolina.Two principal types of corundum deposits are found at Buck Creek the vein type and the corundum-bearing amphibolite dikes.The vein deposits occur in structural fissures that strike north to northeast in a gangue of feldspar, zoisite, an, chlorite. The corundum is generally coarse-grained and good-quality. The corundum content varies from several percent to 50 percent.The corundum in the amphibolites is more or less disseminated through the dike, is generally lower-grade, and is less in quantity, than the vein corundum. About 50 percent of the amphibolite corundum is coarse enough for snagging-wheel grade but is difficult to separate from the amphibolite.Production from the Buck Creek area has been small and came mainly from high-grade pocket in the vein deposits. Pratt 3/ reports 300 tons of corundum ore was produced to about 1896. No record of subsequent production is available.The critical shortage of corundum during the war, due to transportation difficulties and the depletion of deposits abroad, prompted the Bureau of Mines to investigate domestic reserves.After a favorable report was obtained on the Buck Creek area, the Bureau began exploration of the deposit in September 1943 and continued until February 1945."

Apr 1, 1947

Jan 1, 1997

By J. N. Van der Merwe

The current state of the South African mining industry is briefly reviewed from the point of view of an engineer not schooled in the finer details of predictive economics. Based on the assumption that current world exploration targets are indicative of which commodities the world will want in the future, it is concluded that the South African mining industry will continue to be viable and growing well into the future. South Africa holds the minerals the world wants and needs, and as long as the world has people, the demand for those, including gold, will continue to grow. There still is a growing demand for vanity commodities' and even the demand for platinum as a jewellery material displays significant growth. Mine safety still needs to improve, but significant improvement has already been made although the industry is not always acknowledged for the effort in this field. The safety target set for 2013 is within reach but will require sustained effort. The physical mining conditions for the main revenue earners, coal, platinum, and gold, will change substantially in the near future. Research in mining has declined alarmingly and it is urgently necessary for that to be revitalized to generate the knowledge that will be required. In order to streamline the transfer of knowledge to the mining engineers of the future, research needs to be conducted with the full involvement of the universities. It will also be necessary for the universities to continually review curricula to incorporate the latest knowledge and to embark on a campaign of knowledge transfer to the older generation of mining engineers. The mining industry is well supported by the universities, who have done their duty with regard to societal transformation, and the universities are in turn supported by the industry through vehicles like the METE Industry is also strongly supported by a number of professional and vocational societies. The SAIMM will continue to play its vital role as the meeting point of the mining technical sciences, and will continue to disseminate knowledge via the journal, schools, and conferences. In the future, it will review its modus operandi to support the needs of growing membership in the remote branches. It will enter the research arena in an appropriate manner and give effect to the developing integration of mining and society. The most important threat to the future of the mining industry is the recurrent mention of nationalization. While interaction between the mining industry and political and economic development of South Africa has always been characteristic, the current debate is emotional more than rational, and engineers are not well equipped to participate. This matter needs to be finalized before it becomes a popular force that politicians cannot control.

Jan 1, 2011

By R. C. D. Phillis

The annual mine planning process is one of the most important tactical/operational steps towards achieving strategic goals. These tactical plans are part of a very comprehensive Mineral Resource Management process, with the natural sequel to planning being execution. The execution of an underground hard rock mine plan is a multi-project environment that comprises many development-construction-equipping-stoping single project paths, which are referred to as ?stoping paths?. The uncertainty that typifies execution of projects comes in the form of untimely disruptions to constituent tasks and/or project paths. Annual mining plans also include quantified objectives for occupational health and safety, production, quality, cost, employee morale, environment, and corporate social investment. Such objectives make for a highly complex environment that management must contend with?complex in the sense that all the paths and objectives have interdependent constraints. Furthermore, at the time of this paper, Sections54*and 55**of the MHSA*** put the onus on management to ensure legislative adherence. It stands to reason that planning estimates allow excess capacity?buffers?that cushions the impact of untimely disruptions. This paper concerns the fact that despite all the buffers allowed for, time, scope, and budget creeps impact on mine planning and threaten its successful execution. As a consequence, the paper deals with buffer management, the essence of Critical Chain Project Management (CCPM). Effective buffer management provided strategic (executive level) updates without losing the tactical/operational detail necessary for job card creation, especially where professional skills and experience are in short supply. Indicative bottom-line results showed CCPM to be highly effective.

Jan 1, 2011

By H. A. Doerner

"Statistics show3 that in 1927 the United States consumed 60 per cent of the world's production of chromite and produced none. The uses of chromium are rapidly expanding, and a dependable supply is essential to our industries. Since the political and commercial control of our supply of chromite is now in foreign hands it is prudent to determine how this nation can best prepare to supply its need for chromium if the imports were cut off or restricted and whether it is now possible and desirable to stimulate production of chromium from domestic deposits. We have only small amounts of chrome ore of high enough grade to meet present trade requirements. Therefore the Bureau of Mines is making a study of methods for beneficiating our low-grade ores.Chromite (Cr203.Fe0), is the only commercial source of chromium. For refractories, a minimum of 40 per cent Cr203 and a low silica content (5 to 8 per cent) is usually specified. In most instances bricks or lumps having a physical structure that will not crack when heated are required. The only way an inferior ore could be adapted to this use world be to concentrate it and develop a satisfactory binder to make bricks out of the concentrates.For making ferrochrome the requirements are a minimum of 45 per cent Cr203 and an iron content not exceeding one-third of the chromic oxide. On some low-grade ores gravity concentration will give a product meeting these requirements; other ores yield concentrates containing too much iron or other impurities to be saleable."

Jun 1, 1930

This paper endeavours to lay as concisely as possible, before the members the salient features of local gold milling practice, and to point out in what respects this practice differs from that of other large mining camps. This is essentially a free milling ore the gangue being quartz and the gold occurring in a coarse form. At times the ore crushed contains a good deal of slate, the latter imparting to the tailings a somewhat leaden hue.Small amounts of sulphides, chiefly iron pyrites, and at times smaller quantities of arsenical pyrites, zinc blende, and galena are contained in the stone. The average amount of sulphides contained in the ore cannot well be ascertained, as the concentrate obtained in all cases contain too much silica to form a basis of calculation...

Jan 1, 1902

By P. Quinn

"The Venturi-aerated flotation column (VAC) is based on a reactor and separator design for a new generation of flotation machines. The reactor is a Venturi tube, where the air/slurry contact takes place with intensive aeration for efficient particle collection. The separator is a column of 1-3 m length that provides quiescent hydrodynamic conditions for effective separation of bubble-particle aggregates from the remaining slurry.Aeration in the Venturi tube occurs via two mechanisms: air dispersion and nucleation (cavitation). By forcing air through a restricted passage with a fast flowing slurry stream, air is dispersed into fine bubbles. Bubble formation due to cavitation occurs on the surface of particles in the low-pressure section of the Venturi, from dissolved air contained in the liquid.Size-by-size recovery and flotation rate constants were determined for a small-scale laboratory Venturi-aerated flotation column. The results were compared to those obtained in a laboratory 2.2 L Denver cell. It is shown that the Venturi-aerated flotation column has slightly slower flotation kinetics to the Denver cell, but with much higher flotation selectivity. A portable Venturi-aerated flotation column can effectively be used to investigate process or equipment problems in operating plants.INTRODUCTIONFlotation processes can generally be divided into two sub-processes: 1) selective collection of hydrophobic particles by air bubbles and 2) separation of bubble-particle aggregates from hydrophilic particles that remain in the pulp. The methods of aeration, or bubble generation, control the mechanism of particle collection by either collision with, and subsequent attachment to bubbles, or by in situ bubble formation on the surfaces of hydrophobic particles. A flotation device should provide optimal aeration conditions for efficient particle collection and a suitable hydrodynamic environment for effective removal of bubble-particle aggregates from the remaining pulp."

Jan 1, 2002

By I. W. Farmer

Weightings and water inflows into longwall workings often occur together, giving rise to discussions on their relative genesis. Case histories are introduced which indicate that most water inflows are associated with heavy weightings. Resultant large releases of energy can lead to extensive vertical fractures, which can drain water from aquifers or other sources, such as separation accumulations, onto the face. Effectively control of water inflows in these cases depends on face support and weighting control.

Jan 1, 1996

Scope / Agenda ? What is Situation Awareness (SA)? ? Background on SA theory ? SA is critical in a wide variety of domains ? SA and human performance ? Consequences of poor SA ? Significant challenges for SA in mining operations ? Technology centric design ? SA-oriented design methodology ? Goal-Directed Task Analysis ? Design ? SA Measurement and Evaluation ? Applications of SA-oriented design

Aug 1, 2013

By I. Hague

Support liners for underground applications include steel and timber sets, meshing and lacing, screen/mesh, shotcrete and thin support liners (superskins). Over the past few years, major advances have been made in the design and application of liners; especially shotcrete and thin support liners. For shotcrete in mines these advances include the common use of slick-lines to solve logistics problems, the design of alkali free accelerators, the use of synthetic fibres and the new generation application equipment. The field of thin support liners is a new one but advances have been dramatic. This paper discusses the progress made and the need for standardization in definitions and testing for thin support liners. It concludes that the newer technologies have a huge potential positive impact on the industries, from both safety and cost points of view. Le chemisage de soutènement pour extraction souterraine comprend des cadres d’acier ou de boisage, mailles et chapeau, cribles/mailles, béton projeté et des chemisages minces de soutènement (super-peaux). Dans les dernières années, des progrès considérables ont été fait dans la conception et application des chemisages, en particulier les chemisages de soutènement en béton projeté et les chemisages minces. Pour le béton projeté dans les mines, ces progrès comprennent l’utilisation courante de lignes de minerais broyés fin pour résoudre des problèmes de logistique, la création d’accélérateurs sans alcali, l’usage de fibres synthétiques et d’une nouvelle génération d’outillage. Le domaine des chemisages minces de soutènement est très récent mais les progrès ont été rapides. Cette étude présente les progrès accomplis et discute du besoin de standardisation dans les définitions et les tests pour chemisages minces de soutènement. La conclusion est que les technologies nouvelles présentent un énorme impact potentiel positif sur les industries, du point de vue à la fois de la sécurité et de la rentabilité. Unterstützungsverkleidungen für Untertaganwendungen inkludieren Flecht und Seilwerk, Gitter/Geflecht, Spritzbeton und dünne Unterstützungsverkleidungen (superskins). Während der letzten Jahre wurden grosse Fortschritte im Design und in der Anwendung der Verkleidungen gemacht; besonders bei Spritzbeton und dünnen Unterstützungsverkleidungen. In Bezug auf Spritzbeton in den Gruben schließen diese Fortschritte den allgemeinen Gebrauch von Rutschbahnen ein um Logistikprobleme zu lösen, das Design von alkalifreien Akzeleratoren, den Gebrauch von synthetischen Fasern und die neue Generation von Anwendungsausrüstung. Der Bereich der dünnen Unterstützungsverkleidungen ist neu, aber die Fortschritte sind drastisch gewesen. Diese Arbeit behandelt den erzielten Fortschritt, die Notwendigkeit der Normierung in den Definitionen und in der Prüfung dünner Unterstützungsverkleidungen. Sie kommt zum Schluß, daß die neueren Technologien, sowohl vom Gesichtspunkt der Sicherheit als auch der Kosten, eine sehr große potentielle positive Auswirkung auf die Industrien haben.

Jan 1, 2003

By Ivan E. Goodner, Charles H. Fulton

THE subject of the constitution of copper-iron mattes has received considerable attention in recent years by Keller,1 Bolles,2 Hofman,3 and Gibb and Philp.4 Still more recently Friedrich, Röntgen, Wiedmann, Heyn and Bauer, and Leroux have published, in some instances, elaborate researches on the various systems of the sulphides, and the sulphides and their respective metals, which enter into the constitution of mattes, and have added very greatly to the knowledge of the subject. The work of Friedrich has been especially fruitful. But to date no effort has been made to correlate the data obtained in the latter researches and apply then to the study of the product called " matte," which is made in such large quantities by copper and lead-smelters. In this paper we propose to determine, by metallographic and chemical means, the constitution of copper-iron and copper-lead mattes in the light of the recent data above mentioned. We do not discuss copper-nickel mattes or speisses (artificial arsenides). The paper is divided into three sections I. A review and discussion of the various binary systems of the metallic, sulphides, and the binary systems of various metals and their respective sulphides entering into the constitution of mattes; also a discussion of the physical and chemical properties of these sulphides. II. A description of the results obtained from the chemical and metallographic examinations of the samples of copper-iron and copper-lead-iron matte obtained from various plants.

Nov 1, 1908