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The typical reactions which the reductants undergo during ferroalloy production are reviewed, and identified as reaction with CO2 and with SiO, and dissolution in metal. Available reactivity tests for these three reactions are reviewed. It is proposed that it is worthwhile considering dissolution kinetics as a reactivity parameter. Greater crystallinity of the reductant decreases CO2 and SiO reactivity, but increases dissolution rates.

Jan 1, 2002

By P. H. Reynolds, S. Liaghat, A. Zarasvandi

"Darreh-Zerreshk and Ali-Abad are two relatively small porphyry copper-type deposits in Yazd Province in central Iran. They are located within the central Iranian volcano-plutonic belt, formed above the collisional convergent margin of the Iranian lithospheric plate from the late Eocene to the Miocene. This paper discusses the geochemical characteristics of the igneous rocks, and 40Ar/39Ar geochronology of plutons and alteration phases associated with the Darreh-Zerreshk and Ali-Abad deposits. The deposits are spatially associated with igneous complexes that consist of older and barren granites intruded by intermediate-composition granitoids, which are the carriers of Cu mineralization. The granites have relatively high content of Nb, Y, and K, a prominent negative Eu anomaly, and were probably derived from melting of, or contamination of mantle-derived magmas by, continental crust. Porphyritic diorites, quartz monzodiorites, and granodiorites show enrichment in light rare earth and large-ion lithophile elements, depletion in middle rare earth elements, and have no negative Eu anomaly. These intermediate-composition granitoids were derived from melting of the upper mantle or lower crust, and their differentiation was controlled partly by fractionation of hornblende. A pilot K/Ar whole-rock dating study suggests that the pre-ore granites were emplaced in the Oligocene. Dating by the 40Ar/39Ar method of nine samples of secondary biotite and sericitized rocks from drillcore within the mineralized and altered zones in both deposits yielded a well-defined age of ca. 16 Ma. This date is interpreted to be the time of hydrothermal alteration and of porphyry copper type mineralization in this part of Iran."

Jan 1, 2007

By A. Krishnan

Keywords: Tantalum extraction, SOM Technology, inert anode, membrane stability The Solid Oxide Oxygen Ion conducting Membrane (SOM) technology offers great potential for environment friendly and energy efficient extraction of high-energy content metals. This work was performed to demonstrate the technical and commercial viability of the technology to produce tantalum metal directly from tantalum oxide and ore concentrates using a solid-oxide, oxygen-ion-conducting membrane (SOM). The process can be used to efficiently produce tantalum metal without expensive pre-processing of raw materials and without harmful by products. The work reported in this paper is: the proof that high purity tantalum metal can be produced, study of the electrochemical behavior of the cell and the method to increase membrane stability.

Jan 1, 2005

The nature of the specialty glass and ceramic business magnifies the dependency of the ultimate product on the unique properties of their raw materials used to make them. This dependency has implications in the management of risk in the supply process which requires a special procurement organization and program commitment to be successful. The Coming system of managing critical materials and factors in development of alternate new suppliers and products is discussed.

Jan 1, 1989

A hard lump char containing only 4 to 5 per cent ash, 0·25-0·30 per cent sulphur and a trace of phosphorus has been produced from Latrobe Valley brown coal by slow drying and carbonization of ordinary industrial briquettes at temperatures between 7000 C and 14000 C. The briquette char can be made with a variety of reactivities by varying the maximum temperature of carbonization; the higher the temperature, the lower the reactivity. The strength of the fuel compares favourably with metallurgical coke made from black coal, though it may not be quite so resistant to abrasion. Experiments in a small experimental cupola indicate that it will make a satisfactory fuel for use in iron foundries. It may also find extensive application as a smokeless fuel in other branches of industry and in household heating appliances.INTRODUCTIONVictoria, like South Australia and Western Australia, is apparently without 'significant deposits of black coal of coking quality but there are huge reserves of brown coal of high moisture content (60-66 per cent) in the Latrobe Valley (well over 20,000 million tons have been proved) and there are other important deposits in the south central portion of the State (Herman, 1952).For three decades Victorian industries, including a few metallurgical firms, have been using the briquettes made at the Yallourn factory of the State Electricity Commission of Victoria (S.E.C.). These briquettes, having a moisture content of about 15 per cent and a calorific value of approximately 9,500 B.T.U. per pound, are satisfactory for certain grate-type furnaces but they are not suitable for use in cupolas of other shaft furnaces because they disintegrate badly on rapid heating.

Jan 1, 1956

By Joseph L. Jordan

Coal is essential to America?s future energy needs. To meet these needs mining methods must be safe, economical, and environmentally acceptable. Belt conveyor systems for coal haulage from surface mines offer great potential in this situation. The advantages over conventional truck haulage are particularly promising for area strip mines in western coal fields such as the Powder River Basin where relatively thick, flat-lying coal seams occur. The current demand for low-sulfur coal specifically emphasizes the need for better mining methods in these areas. Underspoil haulage is the term applied to transportation of coal from the pit to the surfate in area strip coal mines by belt conveyors in tunnels under the spoil. The advantages over trucks include lower manpower requirements, greater pit safety and efficiency, and improved reclamation procedure. This evaluation includes a comparison of total mining costs for truck haulage versus six variations of the underspoil haulage concept. The more efficient of these underspoil haulage systems have economic advantages over truck haulage which become more pronounced with deeper overburden, thicker coal, and higher annual production.

Jan 1, 1977

By D. P. Roberts

This investigation aimed to simulate the experiments performed by Nic Gay (Gay, N.C. 1976. Fracture growth around openings in large blocks of rock subjected to uniaxial and biaxial compression. International Journal of Rock Mechanics and Minining Sciences and Geomechical Abstracts, vol. 13. pp. 231-243) on fracture growth around openings in blocks of rock subjected to uniaxial and biaxial compression, using the Elfen discrete element code. The results of the physical experiments indicated a number of trends that were successfully replicated in the numerical simulations, including crushing ahead of the face, the formation of a sub-vertical tensile fracture at centre-span, the formation of groups of fractures originating from the crushed face zone, the formation of large corner-to-corner fractures which precede sample failure, and linking of slot corner and sample corner fractures leading to sample failure. In addition, other features were apparent that were not reported by Gay. It is believed that these took the form of conjugate shear fractures (as reported by Gay in a previous paper) and other features that may have been altered or inhibited by the presence of pre-existing structure in the physical samples. It was found that the samples, though nominally made up of the same rock type, must have had significantly differing properties. The presence of pre-existing structures may have contributed to this discrepancy. Strain measurements from the physical experiments were reasonably well matched, except where the gauge lay directly in the path of advancing fractures.

Jan 1, 2012

By K. Galovich, P. Krivokuca

"Quinsam coal mine is located about 25 km west of Campbell River on the east coast of Vancouver Island, British Columbia. Using continuous miners in a fully mechanized retreat room-and-pillar operation, it produces low sulphur, “super compliance” thermal coal for domestic and international markets at a rate of about 2600 t/d. Currently, 65 people work at the site, including some corporate employees.Opened in 1993, the Quinsam mine had a dismal safety record until 1997. Lost time injuries and medical aids were unacceptably high. In 1998, a change in corporate structure brought a change in safety attitudes; a total and unequivocal commitment to safety as job No.1 by corporate and site management. This commitment was clearly spelled out in a new mission statement, circulated to all employees by the new President and CEO, David Slater: “Safety is job No. 1; Production flows from safety; and Think safety at all times.” As well as re-defining workplace safety practices, QCC tightened engineering controls and enforced strict adherence to mine plans.This paper provides a general background to the mining operation, and describes the safety practices that have resulted in an enviable safety record in recent years, reflected by provincial and national recognition."

Jan 1, 2004

By P. Sklenicka

Remediation of the environmental (and social) disturbances caused by opencast brown coal mining in the past in north-west Bohemia isa priority for state environmental policy. In order to provide a concept for full restoration of land following disturbance by opencast mining, a special interdisciplinary project supported by a grant from the Czech Ministry of Environment was started in 2000. The initial stage of the project was intended to summarize and evaluate the findings and the works carried out in connection with various reclamation activities in the afflicted area over a period of more than 50 years. The main aims of the three-year project are to make use of the best available landscape environmental management knowledge in order to harmonize the ecological, aesthetic, productive and social functions of new valuable landscape, including the recovery of historical continuity and an understanding of ?landscape memory?. The basic landscape functions were assessed on two different scale levels. On a large scale, the relevant attributes were investigated over the whole area of the Sokolov brown coal basin (220 km2). The data and experience acquired were used to define large-scale guiding principles for the rehabilitation of a post-mining landscape. On a small scale, the basic characteristics and functions of the landscape were analysed in the Litov-Chlum model area (2 km2). The information derived from this analysis was used to formulate a small-scale approach for the rehabilitation of the model area and also to define general methodological principles. Keywords: rehabilitation, post-mining landscape, degraded landscape, non-productive priorities

Jan 1, 2004

The paper is a general review of practice in design of sub-level open stopes in Northern Rhodesian copper mines and gives examples of some interesting developments during the last five or six years. It discusses the effect of hangingwall subsidence and the methods used to combat rock pressure on working areas.INTRODUCTIONAll producing mines on the Northern Rhodesian Copperbelt have large ore reserves and are designed for high rates of production. The three mines (Mufulira, Rhokana Corporation, and Roan Antelope) where sub-level open stoping is used, hoist from 250,000 to over 400,000 short tons of ore a month so that any stoping method used must be adaptable to concentrated' mining. Individqal stopes produce from 5,000 to over 25,000 short tons of ore a month.Structure af the ore bearing sediments is simple; faulting in ore is almost entirely absent and copper mineralisation is found in the same beds over great distances...

Jan 1, 1954

By Max Roesler

I. INTRODUCTION THE following article concerns the geological occurrence of the iron-ore deposits on the south coast of Cuba. The article is based on a detailed field study, made in the hope that some information would I gained which might be of value in the search for further orebodies, Or in the economic development of the ore already found. LOCATION The iron-ore deposits of the Firmeza district lie near the coast, in the southeastern part of Cuba, in the Province of Oriente. The orebodies of this district form part of a belt of deposits that extends from Sigua, 25 miles east of Santiago, to Sevilla, 5 miles east of Santiago, and lies on the seaward slope of the Sierra Maestra range of mountains.

Jan 10, 1916

By R L. Brathwaite

Previous paleodepth studies of low-sulphidation epithermal Au-Ag deposits in the Coromandel region indicated that economic gold mineralisation was generally limited to a depth zone of 100 to 400 m below the paleosurface. Notable exceptions are Waihi and Karangahake, where ore shoots extended to depths of about 750 and 900 m respectively. These studies have been extended to include Au-Ag, Hg and Sb epithermal deposits in Northland and the Taupo Volcanic Zone. The main paleodepth indicators used are sinters and hydrothermal eruption breccias, hydrostatic pressures estimated from homogenisation temperature measurements on fluid inclusions, and hydrothermal alteration mineralogy. Also the occurrence of lacustrine and fluvial sediments is an indicator of the paleosurface at their time of deposition. Selected paleodepth indicators have been compiled and mapped in a GIS environment. The distribution of the paleodepth indicators are used to define regional variations in erosion levels, and may be useful in predicting areas most likely to preserve the optimum depth window for gold deposition. In the Coromandel region, regional stream sediment geochemical data has also been used to broadly define erosion levels in terms of Zn, Pb and Cu representing deeper base metal zone mineralization and Hg and Sb representing shallower cinnabar and stibnite mineralisation. The interpretations of paleodepth and potential reconstruction of paleosurfaces are limited by the paucity of data, poor age control on the paleodepth indicators and the epithermal deposits, and marked relief and complex stratigraphy in the volcanic terranes.

Jan 1, 2003

By A. Ersoy, M. D. Waller

The principal factors which require consideration in predicting drilling rates are the bit-type, the bit operating parameters and the characteristics of the penetrated rock. A single index is not a sufficient basis for predicting performance. A variety of rock types were drilled in the laboratory with polycrystalline diamond compact (PDC) and impregnated diamond core bits using a fully instrumented drilling rig at different rotational speeds and with a range of weights on the bit. Quantitative determinations of a wide range of textural, mechanical and intact rock properties were also made. Multi-variable linear regression analysis was then used to develop predictive models of rates of penetration from the operating and rock property data. The models have been verified by statistical tests. The analysis indicated that the models for the pin and hybrid PDC bits have potential for practical application. However, although the model for the impregnated diamond bit appears to be reasonable from a purely statistical point of view, it may not be satisfactory for drilling uses as it is based on two measures of rock hardness alone. The application of multiple regression analysis to PDC drilling performance is novel and the technique shows promise for the prediction of rock drillability with PDC bits. The ability of the technique to provide a mathematical characterisation of the performance of new drill bits in specific rocks may prove to be of value to drill manufacturers and users

Aug 1, 1995

Cobalt/tungsten mineralization at Mt. Cobalt, located 170 km southeast of Mt. Isa in northwestern Queensland, is described. Mineralization occurs in the Kuridala Formation of the Mary Kathleen Group, which is composed dominantly of pelitic schists, carbonates and acid and basic volcanics.Rocks in the region are metamorphosed to amphibolite facies and affected by two generations of tight to isoclinal folds and a third, more open generation of folds. The region is divided into three meridionally trending belts on the basis of structural style, with mineralization concentrated in the central, more highly strained belt.Deformation and metamorphism is probably younger than 1670 m.a., and the rocks are intruded by granitic rocks dated at 1509 ± 22 m.a.Mineralization occurs in shear zones at the contact between an amphibolite and enclosing pelitic schists, and within the amphibolite itself. Mineralization consists of cobaltite and scheelite with lesser chalcopyrite, pyrite, pyrrhotite, i1menite, allanite, xenotime and apatite. The mineralizing event involved addition of K, Cl, CO2 W, As, Cu, Ni, Au and rare earths and depletion of Ca and Na. It altered a hornblendeandesine/labradorite host assemblage to a biotiteoligoclase/andesine-scapolite assemblage. Though tourmalinealteration also occurs, it is probably not related to mineralization.It is concluded that the mineralization and alteration assemblages formed by reaction of saline fluids with amphibolite close to the peak of amphibolite facies metamorphism.The fluids are probably metamorphically derived, and their movement was channelled through high strain zones in the sequence. The material carried by the fluids was derived from the metasedimentary/metavolcanic pile as a whole.Other deposits in the Mt. Cobalt-Selwyn area have characteristics comparable with Mt. Cobalt, and the mechanism for the genesis of Mt. Cobalt may have applications at other areas in the region.

Jan 1, 1983

By Robert Hopler

In the annual report under the Explosives Act for 1905, H.M.inspectors state that over 90 percent of the accidents causing death or personal injury occurred in the use of explosives and under miscellaneous conditions to which the controlling provisions of the Act do not apply, and that such accidents caused 43 out of the 50 deaths, and 312 out of 348 cases of injury. The number of accidents grouped under the heading of “Use and Miscellaneous” is less than that for 1904 - viz., 281 against 301. By these accidents 43 persons were killed and 312 injured, as compared with 39 killed and 343 injured in 1904

Jan 1, 2007

By D. Witchard, G. C. Penny

An important conclusion of the study is that altering the properties of the granulation water is a practical way of improving the sintering performance of blends that contain porous ores, and more work is under way to investigate other additives. Previous studies of iron ore blends containing pisolite ore showed that losses in sintering productivity were a result of deteriorating green-bed permeability. Pisolite ores are extremely porous and absorb a proportion of the water added during granulation. Although increased water addition could be used to counteract losses in productivity, the current study examined methods of inhibiting water absorption by pisolite ore as a means of improving productivity. Additives were used to alter the properties of the granulating water. With no increase in mix moisture contents pilot-scale sintering studies showed that sugar-based additives gave productivities that are higher than those obtained for a comparable ore blend containing haematite rather than the pisolitic ore. Several techniques of adding the sugar to the sinter mix were examined and found to increase productivity to varying degrees. Theoretical considerations, in some cases supported by experimental results, indicate that sugar-based additives not only inhibited water absorption by porous ore particles but also improved the permeability of the sintering bed. The study also suggested that, contrary to some commonly held views, the highly reactive nature of Yandi ore from Western Australia is beneficial for sintering. Porous ores enabled the formation of a strong sinter at fast flame-front speeds-both good strength and a short sintering time are requirements for high-productivity operation

Jun 18, 1905

By A. Kale

A chlorination pilot plant having capacity to produce 5?10 kg/hr of titanium tetrachloride is in operation at the chlorination facility in Mintek. The bubbling fluid bed chlorination plant can be operated in batch and/or continuous process to study the chlorination kinetics of various feedstocks. The chlorination of titaniferrous ores to produce titanium tetrachloride (TiCl4) was carried out during the commissioning of the pilot plant and also as part of the titanium programme carried out at Mintek. TiCl4 is a basic raw material for producing commercial titanium dioxide pigment and titanium metal. This paper discusses the challenges faced during the commissioning and operation of the chlorination pilot plant. It also discusses the effect on the auxiliary facilities and instrumentation as a result of the harsh operating conditions of +1000°C and use of corrosive gases like chlorine and titanium tetrachloride. It discusses the effect of physico-chemical properties of the titanium tetrachloride and iron chlorides. The effect on the chlorinator refractory lining due to heating and cooling of the chlorinator is also discussed. Besides the special provisions made during the design of the chlorinator, this paper also discusses the operational experience and possible solutions to be implemented in future. Keywords Fluid bed chlorination, titanium ore chlorination, titanium tetrachloride (TiCl4) production using fluid bed technology.

Jan 1, 2011

Seam correlation in the central Rapahoe Sector (Greymouth Coalfield) can be enhanced by detailed lithostratigraphy and chronostratigraphy. Rewanui Coal Measures are overlain comformably by lacustrine, deltaic and fluvial strata, and this upper contact can be located using lithological and geophysical log character. The Cretaceous-Tertiary Boundary (KTB) occurs near the top of Rewanui Coal Measures and has been identified palynologically in 16 drillholes. The Rapahoe Sector can be subdivided into two palynostratigraphic domains which adjoin along a basement normal fault which was downthrown to the north during coal measure deposition. The KTB provides an isochronous surface which is independent of the lithostratigraphic datum. Using the KTB as a datum, the æUpperÆ, æMainÆ and æSubmainÆ seams can be reliably correlated throughout the southern and central Rapahoe Sector. Similarly, the æSubmainÆ seam can be correlated with æcÆ seam of the Strongman Mine area, though other Strongman seams are absent from the central and southern Rapahoe Sector.

Jan 1, 1996

By Chester M. F. Peters

The opportunity to make a close study of the available geologic data existing along the line of the California Aqueduct crossing of the Garlock fault in the Tehachapi Mountains was brought about first by my involvement in the prebid examinations, and later with contractors' claim cases. The California Aqueduct crosses through the western end of the Tehachapi Mountains and cuts across the Garlock fault zone at a location about 9 miles east from its junction with the San Andreas fault zone. This is about 65 miles northwest of Los Angeles and 38 miles southeast of Bakersfield (Fig. 1) (1). This map was published after the tunnels were started and shows the corrected geology. At the crossing the fault has north and south branches which extend northeastward for about 22 miles before converging. In the vicinity immediately east of the tunnel line the north branch of the fault starts to converge toward the west. After crossing the line it passes under the upper plate of the apparent easterly extension of the Pastoria thrust fault, so the actual junction with the south branch is obscured. The aqueduct design called for the expected active slip zone of the north Garlock fault branch to be crossed by the 2,800 foot long Pastoria siphon, which connects with the north portal of Tehachapi Tunnel No. 3. The tunnel would extend through the western end of Genghus Ridge which lies between the north branch and the main south Garlock fault zone in Beartrap Canyon. Here again the

Jan 1, 1997

By J. Stacey

This study was undertaken to generate a locally relevant guideline for the socio-economic aspects of mine closure for South African closure practitioners and decision makers. It should also represent a resource for interested and involved stakeholders. Mine closure, and its related post-closure social, environmental and economic characteristics, is part of the lifecycle of mining operations, given the finite nature of the ore resource. Many coal mines are anticipated to close in the next ten to fifteen years in Mpumalanga, as the epicentre of the industry shifts towards the Waterberg. Social aspects of mine closure have been historically underplayed, and under researched. Coaltech thus commissioned two studies, the first of which examined the closure dynamics of 36 mines in Mpumalanga and KwaZulu-Natal in 2006. A follow-up study (July 2007) focusing on Mpumalanga3,4 confirmed some of the results of the first study. It also contained broad guidelines for mine closure covering social and labour planning, job creation, the use of mine infrastructure, developmental incentives, and environmental rehabilitation.

Jan 1, 2010