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By Tatiane Augusta Almeida dos Santos

A evolução da microestrutura de um aço inoxidável bifásico com estrutura martensítico-ferrítica (AIMF) desenvolvido pela Vallourec Tubos do Brasil S.A. foi estudada durante o tratamento térmico de revenimento através de medições in situ das frações de fase por difração de raios X. Para a liga de AIMF o revenimento é realizado para ajuste das propriedades do material e assim como ocorre com as ligas de aço inoxidável supermartensítico (AIS), este tratamento é realizado em temperaturas intercríticas. Após o resfriamento, uma quantidade da austenita revertida pode se transformar novamente em martensita enquanto outra pode permanecer retida na estrutura. Para conhecer melhor a ocorrência deste fenômeno para a liga de AIMF é essencial avaliar a sua evolução microestrutural durante o revenimento. Neste trabalho, a reversão da austenita em diferentes temperaturas de revenimento foi analisada através de difração de raios X in situ. As amostras foram também caracterizadas por microscopia eletrônica de varredura. A propriedade mecânica após diferentes condições de revenimento foi avaliada em ensaio de tração. Foi observado que há uma temperatura crítica em que a austenita revertida se torna mais estável e não se transforma durante o resfriamento subsequente.

Aug 7, 2018

The Río Agrio of northern Patagonia, Argentina, is highly acidic due to inputs of volcanic gases (SO2, HCl, HF) in its headwaters. The watershed includes a hyper-acidic (pH <0.5) volcanic crater lake, a larger glacially carved lake that is also strongly acidic (pH 2.6 to 2.7) and an acidic river that flows for more than 40 km (25 miles) before its pH is completely neutralized. This unique watershed has many geochemical and biological similarities to acid waters caused by mining. This paper describes the Río Agrio watershed and draws a comparison with some famous acid mine waters. Learning more about naturally acidic lakes and river systems could have important applications to the bioleaching of ores or biological treatment of mine waters. Therefore, it should be of interest to the general community of mining and metallurgical engineers.

Jan 1, 2008

By Dhanesh Chandra

[The U.S. Ucparunent of tlIe III LeriOr, Bureau of 1?Ilnes, lnta dcvcltil- (I a m.?tl,nd to extract nickel, i:ob.tll and IlIIicr Valuc:l,1, mrl?tl., lrom I.ow grad:, dumusI it Inlet itc.: :isin;; a rarb-i mnnnxid:: reducl.iun and ,innnonln/mumonlum sull,h.Ito Icitcll Col lowed by solved. evil let foil and clot tr:,winnfu,;. &apos;I &apos;o rain bcLtur undcI&apos;sLandin;; uI the producLs reduced rind leached with the s;:Item, the liureau of t?Ilite; was enf,ngod In a 1 uinL sl.utly IIt1I the Uuttvcr ltc~:c:n-ch LnstiI-IL-. &apos;I&apos;hr&apos;ut;;h C(Im:drlod ahplit I¬L ion:; of a rotnbIW)L11nl ill eleu Lyon :utJ uplical inicrnscopy, cle trun beau micru,inal?;st?s and X-r.iv tcchnitlaes, Lhc factors jilt] ucncing low nickul e::lracl.on yLrids Iron, ccrlnin l;tteritos wul the hcuefhe al yCferL front addil.I:un u1. r:u)plowt&apos; ruug,ounus and halides have bucn rrvealod. IL leas ht&apos;en shown their nt nliJcrate Lion terlperuLuri&apos;s (5S0°C - 6501C) Lhe 111LACl extraction ylolds were low hccausc of the futmetlt-m of rufrill t,urv sillc:Ite compicxcs during ciii lit Hi [hut COOL.tlu sig nlficnnt anutunls of nickel .Lrui LhaL arc resistant Lu discolullull it, a su6r.C?quent ammnnlIca1 Jcaeh. &apos;This formation ill rulracLorv rnngtieves is altrlbuU?d Lo the prc.srnCV of aluauinum combined with c.ilicun jn addlt.lon In tnnl;neni~im in I.lic Lalerites, Iligb exII.Ictlon yields were oblalneJ when none or only a few I ,fraCLot&apos; e, were InrmeJ. Hit s;intc rcfrarlnry cowl, Icxc5 also lend Lo surround Ow IaaIIiable meI.allle iron-IIIcI:el :iILoy CIUSisling ill the mau&apos;ix, tIll: rrhv nreveu)Ling cuntacr ,Itlt LI5U Jeacl: solution; this, huwrvcr, ran ho ovu:rcoml by At ti itlon .111.11 retieCtiun. &apos;I&apos;hc eIIcc l of prr.reJIctlun .,Ill itivi&apos;s vucli i&apos;s lye iii&apos;, &apos;,udlum "Ill orIde, hv,Irogrn CIIInrILIC, etc., and Lht? 1111,Lre:InrLlI&apos;ll he&apos;e:tleg un Lbe cxLt,icLitin are also iilsr.ussod 111 Lhe rcl,olt.]

Jan 1, 1979

The concentration of Mt. Morgan sulphide ore has always been attended by serious loss of gold. Until recently, with a simple selective flotation flowsheet, even the lowest grade of ore milled-about 2 dwt. per long ton-thislloss was 0&#183;9 dwt., whilst for average to high-grade ore, 3&#183;5 to 5 dwt., the figure was 1&#183;5 to 2&#183;0 dwt. Early in 1937 it was decided to equip the research laboratory for an investigation into the condition and location of the escaping gold and the physical and mineralogical barriers preventing its recovery.With the completion of: this equipment in July 1937, trial and error testing, which had been explored to exhaustion, was abandoned and a five months&apos; research programme mapped out and commenced. Based on the knowledge so gained, a flowsheet combining primary desliming, bulk flotation of the natural slime, selective flotation of the deslimed fraction, and cyanidation of the selective flotation tailing was drafted and tried with encouraging results in a 70-lb. per hour pilot plant. This flowsheet, modified to meet current circumstances, is being dove-tailed into the existing 1,500-ton sulphide ore concentrator, though the cyanidation treatment is actually carried out in the oxidized ore mill, to which the flotation tails are pumped.RESEARCH EQUIPMENT(1) Five tube elutriator (Fig. 1) t built in the company&apos;s workshop.

Jan 1, 1939

By Nur Hossain

Analysis of Linear Elastic Fracture Mechanics (LEFM) parameters via the Virtual Crack Closure Technique (VCCT) has been obtained for SENT specimens of AM6OB magnesium alloy. It is found that the ratio of initial crack length to initial monotonic plastic zone size is one of the critical factors in establishing the limit of using LEFM concepts. If this ratio is below a certain limit (i.e. when crack lengths are small in comparison to the plastic zone size), loss of similitude stress intensity factor range would occur. This ratio, therefore describes the limit below which the use of LEFM would no longer be admissible. In this study, the above limit was established for AM6OB magnesium alloy. In addition, fatigue crack propagation tests were conducted to ascertain the fatigue response of the alloy and determination of the coefficients of Paris model.

Jan 1, 2010

By W P. Breytenbach

"The phased application of statistical process control (SPC) infers that processes are classifiable as pre-SPC (or phase zero), phase I and phase II processes, with different objectives being pursued in the different phases. Phase zero processes, defined as processes affected by assignable causes of variation, are characterised as follows: out-of-control with unknown autocorrelation structure having an unknown statistical distribution not performing consistently on target with minimum variability potentially incapable of conforming to the product specifications. The objectives of phase I SPC is to obtain estimates of the mean (µ), variance (s2), probability density function (f(X)) and the autocorrelation structure, as well as transforming the process into a phase II process (defined as a process conforming to specifications and performing on target with minimum variability). As in any other type of research or pragmatic improvement intervention, sampling is required is to achieve these objectives. The challenge of deciding a phase I sampling plan is multifarious since it has to cope with the aforementioned effects of assignable causes and provide for rigour estimates of the unknown parameters. Furthermore, deciding sampling plans in phase I invariably presents a classical catch-22 situation: appropriate sampling is required to determine the autocorrelation structure of a variable, but knowledge of the autocorrelation structure is required to formulate an appropriate sampling plan. This paper suggests, for random variables, guidelines to formulate sampling plans, and presents a methodology to estimate the inherent process parameters of process variables and an approach to identify assignable causes in phase I.&nbsp;CITATION:Breytenbach, W P, 2014. Rational sampling and standard deviations for random variables in phase i application of statistical process control, in Proceedings Sampling 2014, pp 141–154 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 29, 2014

Six simulations by the Mpnte Carlo method employing both classical and geostatistical techniques are presented for the determination of the probability distribution of the in situ value of a coal seam. To avoid the problem of qualitative estimation of parameter variability in the calculation of an arbitrary seam value, only data values from borehole information were used to quantify the variation in four coai seam parameters.The method which is suggested as being the most appropriate is a particular geostatistical approach that employs the best linear unbiased estimate and the error of estimation for a number of two dimensional blocks. The results indicate that the variance of the coal seam unit value may be much higher than that indicated by the classical approach because of the spatial variability that is properly incorporated in the geostatistical approach.The model used in the Monte Carlo simulation to determine the economic value of a coal seam can be extended to incorporate all those parameters which are necessary for a true estimation of the probability distribution of the coal seam value. A time value concept for discounting can also be incorporated to optimize the economic return of a coal mining project.

Jan 1, 1983

By D. M. Weinberg, S. R. Novascone, R. R. Reynolds, J. H. Cole, C. D. Christensen

The mechanical properties of the rocks surrounding an orbital vibrator alter the shape and amplitude of the vibrator’s orbit. Detecting these changes with driving point impedance measurements promises to reveal fractures and, possibly, identify the in situ stress state and significantly increase the depth that can be investigated. Our research emphasis has been on detecting vertical fractures through casing. Experimental and numerical results to date indicate that our new logging tool has excellent potential for determining both the vertical extent and azimuthal orientation of such fractures. Fracture and in situ stress orientations are useful in mine planning.

Jan 1, 2002

By S. K. Murphy, K. B. Le Bron, A. K. Ward, S. Hayes, T. Rangasamy

A process for evaluating different options for extraction of mining blocks is presented. The process is described and an example of the application of the process to a case study is presented. Un procédé pour évaluer différentes options pour l’extraction de blocs d’exploitation est présenté. Le procédé est décrit et un exemple de l’application du procédé à un cas particulier est présenté. Ein Prozeß für das Auswerten der unterschiedlichen Optionen für die Extraktion von Abbaublöcken wird dargestellt. Der Prozeß wird beschrieben und ein Beispiel der Anwendung des Prozesses zu einer Fallstudie wird dargestellt.

Jan 1, 2003

By K. Morsi

Carbon nanotube (CNT) reinforced metallic composites have been recently generating significant scientific interest, due to their expected superior properties compared with other composites. Out of the metallic matrices investigated for reinforcement with CNTs, aluminum has received considerable attention. A major problem has been the dispersion of CNTs in metallic matrices. This paper discusses preliminary results on the mechanical dispersion of CNTs in aluminum powder, powder processing, stability and characterization of aluminum dispersed with CNTs at reinforcement levels equal to and below 5 wt.%.

Jan 1, 2009

By Campbell Brown GA

IN 1904-5 diamond drilling operations in the Mount Morgan mine proved the presence of some inillioils of tons of rich, copper-gold ore, averaging about 45% to 50% silica and 22%Fe as sulphide. To smelt this ore in blast furnaces, without previous concentration, large quantities of basic flux.were required. Unlimited quantities of cheap, limestone, were available at Marmor, on the GladstoneRockhampton railway, 50 miles from Mount Morgan, but the supply of iron flux was a more difficult problem. Smelting operations started, with one&apos; furnace in January, 1906, using as flux low-grade sulphide ore fro:m. the mine, containing very little silica. When the second, furnace was blown in this was supplemented by ironstone from, small aeposits in the immediate district. It was recognized that these sources of supply would be insufficient to keep the full plant going after the third furnace had been blown in. Accordingly, the deposits at Eabra and Mount Etna were opened, neither of which proved capable of supplying the quantity required viz, 1000 tons per week. Negotiations were meanwhile being conducted with the Marble Island Iron and Limestone Co. to obtain the right to mine at Iron Island, where a sufficiently large deposit was known to exist. Shipments from this source commenced in January, 1907, and ceased at the end of July of this year, when the metallic flux from...

Jan 1, 1912

By S. G. Mougiakakou

A computerized system (SCAPEVIEWER) based on landscape indices and artificial intelligence techniques is proposed in order to classify landscape images into various categories according to the quality of the pictured scenery. Photographs (totally 108) from various landscapes have been clustered, from seven experts in accordance to the mean estimation of landscape quality, into distinctive (C1), typical or common (C2), and indistinctive (C3). For each of the landscape photographs, ten (10) environmental and operational indices have been selected and determined, corresponding to visibility (V), naturalness (N), relief (R), flora quantity (FC), flora quality (F), water (W), skyline (SL), visual entities (G), season (S), and viewer position (P). These landscape indices are fed to a classifier. The classifier is a feed forward Neural Network (NN) trained by a novel hybrid method combining genetic algorithms and the back-propagation algorithm with adaptive learning rate and momentum. A total classification rate of 93.5% has been achieved, using only 8 input neurons. The discarded input neurons correspond to the indices S, and P. The pilot system SCAPEVIEVER has shown the feasibility of landscape photograph classification into three categories (C1, C2, and C3) according to the landscape quality, selecting simultaneously the most robust indices, by means of a computerized system combining the knowledge of an expert with a NN based classifier.

Jan 1, 2003

By C Johnstone

Project management is not a task to be undertaken lightly. Mining projects generally present even more challenges due to ChinaÆs remoteness and complexity. Having experiences in project management in the West is certainly an asset, but China can present the uninitiated with any number of headaches. To undertake a project there can have many problems that are unique to China. For the last 15 years, China has seen an increasing number of foreign capital investment projects in the mining industry. Practices involved in mining project development have experienced/are experiencing an evolution. Since 1996, Sino Gold Mining Ltd has delivered three mines in China, ie Jianchaling Gold Mine, Jinfeng Gold Mine and White Mountain Gold Mine. Through the work, Sino Gold has established a solid knowledge base and a capable and skilful workforce in effectively undertaking mining projects in China. This paper is concerned with the experiences accumulated so far by Sino Gold in project management in China. An overall review is conducted regarding the reform of the mining project development in China. Opportunities and challenges are highlighted within the political, economic and culture context. Brief summaries of the development of the three gold mines are presented.

Jan 1, 2009

By Christopher Cloete Uys, Luis Manuel Poinha Valentim

The purpose of this workshop is to describe and demonstrate the use of SPEEDWAVE, a high speed data recorder, its VOD enhancements, and the software which binds the system together. The system was designed by TLC Sohware, SOUTH AFRICA. TLC is a company spedalising in the solution of engineering problems, using computertechnology as a base. TLC was founded in 1987, and has since been involved in many different.measurement, control, simulation and modelling projects. Wth respect to the blasting industry, TLC has, in conjunction with AECI South Africa/ICI, developed a tunnel mining design aid, a ring blasting design aid, a multkhannel seismograph and a laser surveying program. In 1989, TLC designed and built the BA800. a microcomputer-based high speed recorder. These recorders are still in use and are producing valuable results. Based on improved technology and with the field experience of the BA800, TLC has designed and developed the data recorder SPEEDWWE.

Jan 1, 1995

By Carlos Maurício Fontes Vieira

In the present work a ceramic body, fabricated using a mixture of clays and sand, for roofing tiles, produced in Campos dos Goytacazes, north of the State of Rio de Janeiro in Brazil, was characterized. Characterization was performed by X-ray diffraction, thermo analysis, chemical analysis, particle size distribution determination and plasticity. In addition, technological properties related to water absorption, linear shrinkage and flexural rupture strength were determined in samples fired at 700, 900 and 1100oC. The results showed that the investigated ceramic body has satisfactory plasticity and presents a refractory behavior during firing due to the predominantly kaolinitic nature of the clays.

Jan 1, 2006

By D. D. Blue

To insure domestic production of aluminium for, essential civilian and defense uses, the Government, under authority of the Defense Production Act of 1950, programed and promoted an aluminum-expansion program that will more than double the primary production capacity that existed in 1949. In view of this vastly increased production, the raw materials, with respect to both quantity and sources, are reviewed. The raw-material consumption pattern, the requirements during an expansion period when excess quantities of materials for starting up new facilities are consumed, and the probable requirements for production of 1.7 million tons per year of primary aluminum are discussed. The raw materials that presented the most difficult supply problems were bauxite, electrical power, and fluoride salts, and the supply pattern for these materials probably will undergo changes. A major part of the electrical energy for the increased capacity was to come from thermal generation, Jamaica-was to become a major source of bauxite, and synthetic fluoride salts were replacing natural cryolite in increasing quantities. Other raw-material requirements discussed are: Soda ash; lime, and limestone; starch; filter cloth; fuel; alumina; the carbonaceous materials, green and calcined petroleum coke, high-and low-temperature pitch and coke or anthracite; cryolite; aluminum fluoride; the materials going into production of synthetic fluorides, acid-grade fluorspar, and sulfuric acid; and labor. INTRODUCTION The raw materials for the aluminum industry that have received the most publicity are bauxite, the ore that supplies elemental aluminum, and electrical energy, the means by which aluminum oxide is reduced to metal. A number of other important materials are, however, required in large quantities in the production of primary aluminum metal.

Jan 1, 1954

By T. S. Lundy, J. I. Federer

Chemically purified Zr95and Cb95 have been used in determining self-diffusion coefficients in the bcc phase of iodide zirconium over the temperature range of 900o to 1750°C. The temperature dependence of the diffusion coefficients could not be described by the usual Arrhenius-type equation over the entire temperature range. Values of the apparent frequency factors (D0)a and activation energies (Q)A for ZR95 varied from 4.8 x 10-6 to 2.5 x 10-2 sq cm per sec and 20,700 to 46,900 cal per mole, respectively, between 900°and 1750°C. Similarly, for Cb95, values of (Do) a and (Q)A varied from about 2.4 x 10&apos;5 to 0.25 sq cm per sec and 26,500 to 56,800 cal per mole, respectively. The data may be described in terms of the a to ß transition temperature of 1136 °K and the absolute temperature of the diffusion anneals by the following eauations: SEVERAL studies on the diffusion of Zr95 in zirconium have been reported.1"5 The values of the constants contained in the usual Arrhenius-type equation for describing the temperature dependence of the diffusion coefficient, D = Do exp [- Q/(RT)], are summarized in Table I. The reported values of Do, the frequency factor, and Q, the activation energy, are seen to vary by factors of about 60 and 1.6, respectively. Examination of the data from any one study indicated reasonable consistency of measurements. The large discrepancies of over-all results, therefore, cannot be explained on the basis of experimental scatter. One possible explanation for the differences in results could be a varying impurity content of the zirconium. Another possibility is that the radioactive daughter, Cb95, influenced the values of some of the determined diffusion coefficients. Therefore, the first of the three purposes of this study was to reconcile the large differences in diffusion results that have been obtained. Several empirical relations have been proposed to relate the diffusion coefficients in solids with physical properties, such as the absolute melting point, the heat of fusion, and the heat of sublimation.

Jan 1, 1963

The purpose of this study was to investigate the immobilization as a host for metallic pollutants (Cr, Cu, Pb, and Zn) by ettringite phase. Ettringite phase is produced through hydration reaction of calcium aluminate with gypsum. From the XRD patterns, it is known that the distance between spaces in 010 planes in ettringite crystal increase with an increase of ionic radius of heavy metal except Pb; no big difference is shown. For this reason, the d-value of 010 planes in ettringite crystal increased with the substitution of Cr, Cu and Zn having a big Al ironic radius. But in case of Pb, because the substitution occurred at calcium site, it does not influence to increase d-value of 010 planes.

Jan 1, 2006

By P Blattner

The Late Miocene gold-silver bearing epithermal system at Waihi has some close similarities in its paleo-thermal and geochemical structure with modern, volcanic-hosted geothermal systems such as Ohaaki-Broadlands. At Waihi an extensive braided quartz vein system is enveloped by hydrothermally altered andesites with minor tuff breccias and tuffs. A main stage of vein filling consists of multiple phases of chalcedonic quartz and fine to medium grained quartz, which are accompanied by pyrite, sphalerite, galena, chalcopyrite and acanthite below the base of oxidation. Platy calcite is present locally. Fluid inclusion studies indicate that the main stage quartz was deposited at temperatures of 189¦-273¦C from dilute (Tm of -0.1 to -1.0¦C) fluids that were locally boiling. Homogenisation temperature Th versus Tm data points lie within the field enveloped by dilution and boiling/gas loss paths determined for the Ohaaki geothermal field, and indicates that the parent hydrothermal fluid for the Waihi epithermal system had a similar composition to that at Ohaaki, ie 0.2 wt% equiv NaCl and 3.3 wt% equiv CO2. The hydrothermal alteration mineralogy and the isotopic composition of vein calcite indicate that the hydrothermal fluid contained relatively high concentrations of CO2 , as at Ohaaki. Oxygen isotope analyses of main stage quartz range from 6.1 to 11.6 %0 and of vein calcite from 2.29 to 9.4%0. Calculated d18Owater values for the hydrothermal fluid that deposited the main stage quartz range from 2.0 to -5.7%0, with a trend to less negative values with depth. They are similar to those in the deep chloride fluid in active geothermal systems with a substantial fluid throughput. A high fluid throughput at Waihi system is also evident from the extensive high intensity hydrothermal alteration and large volume of quartz deposited in the vein system.

Jan 1, 1995

By G. Deschênes

The Eleonore property (James Bay district of Northern Québec), owned by Goldcorp, hosts gold within stockworks of quartz-tourmaline-arsenopyrite veins and veinlets contained within microcline (potassic alteration) and brown tourmaline replacement zones. The preliminary investigation to recover gold from drill core samples showed that flotation followed ultrafine grinding and cyanidation is the preferred option. Ultrafine grinding is used to liberate gold finely disseminated in sulphides. The flotation concentrate used in the investigation had a P80 of 11 microns and contained 75.5 g/t Au, 5.0 g/t Ag, 10.3% S, 0.07% Cu and traces of antimony (0.03%). The mineralogical characterization showed the presence of 65% gangue minerals, 23% pyrrhotite (hexagonal), 9.6% arsenopyrite, 2.2% pyrite and 0.08% chalcopyrite with trace amounts of galena (0.05%) and sphalerite (0.03%). Gold was in the form of native gold and electrum. A straight cyanidation conducted at pH 11.0, DO of 3-5 ppm, 2000 ppm NaCN, 20 C 72 hours extracted 97.0% Au and consumed 31.5 kg/t NaCN. The equilibrium was reached within 24 hours. Increasing the dissolved oxygen to 16 ppm reduced the consumption of cyanide to 22.0 kg/t with 96.7% Au extraction. A 16-h pretreatment with 2.0 kg/t lead nitrate, followed by a 24-h cyanidation reduced the cyanide consumption to 6.0 kg/t with a gold extraction of 97.5%. Increasing the lead nitrate addition to 6.0 kg/t reduced the cyanide consumption to 1.2 kg/t by passivating the surface of pyrrhotite. The gold extraction remained at 97.0%. It was possible to decrease the concentration of cyanide to 800 ppm NaCN without compromising gold extraction. The associated cyanide consumption was 1.2 kg/t NaCN. The passivation of gold grains was an issue when the cyanide concentration was decreased to 550 ppm NaCN. The gold extraction decreased to 92.2%. The average lime addition for all the tests was 7.4 kg/t and the average silver extraction was 80%. Efficient cyanidation of an ultrafine sulphide concentrate with only 800 ppm NaCN represents an advance in leaching of ultrafine sulphide concentrates.

Jan 1, 2013