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By Washington Luiz Mafra

Every year the conventional direct reduction processes ? Midrex and HYL III ? increased their market share in the world steel production, even though they are only economically feasible in countries where natural gas is available at competitive prices. In this context, the new Midrex projects are based on large reactors (Megamod - 1.5 to 1.8 Mt/y of DRI), reduction temperatures of the metallic burden up to 850oC, with bustle gas temperatures between 960oC e 1050oC. Thus, the requirements of metallic burden performance, as well as the evaluating methods, usually based on ISO standards, need to be reviewed. It is well known that the standards usually applied to quality evaluation do not reflect the performance of metallic burden inside the reactors. This paper describes the different methods of evaluating the disintegration under reduction of DR pellets based on ISO 11257 standard. This is the most important method used by pellet producers and customers for evaluating DR feedstocks. The different methodologies tested to evaluate the disintegration under reduction had varying results, evidencing the relevance of the method and the quality of the pellet. Nevertheless, validating the method in an industrial reactor is still fundamental.

May 1, 2007

By W. Dong

This paper presents the fundamental study of the temperature distribution in a reforming planar solid oxide fuel cell (SOFC) using mathematical modeling and experimental testing approaches at Versa Power Systems (VPS). In order to investigate the on-cell temperature distribution under high rates of Natural Gas direct internal reforming (DIR), both the computer simulation approach and the experimental testing approach have been developed. In this work, comprehensive in-house DIR and SOFC models were developed and employed for the computational fluid dynamics (CFD) based 3D computer simulation. The current SOFC module has been corrected to take into account both the on-cell electrical leaking effect and the stack stage structural resistance. Meanwhile, an instrumented single-cell test jig with multiple thermocouples was built, and a series of experimental tests were performed at various conditions. The numerical results based on the single-cell jigs are in very good agreement with the physical test results.

Jan 1, 2005

By M. Medraj, M. A. Arafin, D. P. Turner, P. Bocher

In this study, the kinetics of isothermal solidification during TLP bonding of Inconel 625 and 718 superalloys with nickel based multi-component filler alloy BNi-2 have been studied through a combination of direct experimentation and mathematical modeling in order to determine the effect of process variables and, thus, to optimize the process. The predicted isothermal solidification completion times from the boron diffusion model and migrating solid/liquid interface model were in good agreement with the experimentally determined values and, they were found to be significantly less than those of other nickel superalloys with different nickel based filler alloys. Further, significant reduction of holding time was observed with increasing bonding temperature and with decreasing joint gap. No significant grain growth in the base metals has been observed in the temperature range being investigated (1325 - 1394K).

Jan 1, 2006

By V. C. Pandolfelli, L. Paulino, C. E. Zangiacomi

The continuous improvement in aluminum industry over the last years has increased metal output at lower cost. The potlining plays an important role in this regard due to high cost involved and more recently in its environmental aspects. In order to increase potlife and thus minimize the aluminum cash cost, a systemic approach is needed, through investigating the main cathode failure mechanisms by using a pot autopsy as a powerful tool, and then making the necessary chances to achieve extended potlife. In addition, preheating and pot start-up may also damage the cathode if not performed with an appropriate technique or even if the lining materials are not specified correctly, among other factors. All these aspects will be presented and discussed in this paper. Increased potlife, especially now that the current is reaching values up to 300kA, will allow aluminum plants to match their goals more efficiently at lower costs.

Jan 1, 2006

By W. J. Farley

Location and History The Sherritt Gordon mine is in northern Manitoba, one hundred miles north of The Pas and forty miles northeast of Flin Flon. The original discovery was made by a Cree indian, Philip Sherlett, in 1922. The claims lapsed in 1924 to be re-staked and optioned by various mining groups who carried out a certain amount of development work before relinquishing their options. In 1927 the present Company, Sherritt Gordon Mines, Limited, was formed to take over the property. Production commenced in 1931, but in the following year operations were suspended and it was not until 1937 that the prevailing price of copper pemitted resumption as an economic operation. The mine has operated continuously from that time to the present. Total production to the end of 1947 has been: Copper . . . . . . . . . 301,813 . .,345 pounds Zinc . . . . . . . . . . . 112,636 tons of concentrat (50% zinc) Gold . . . . . . . . . . 83,070 ounces Silver . . . . . . . . . 2,651,317 ounces General Geology The consolidated rocks in the vicinity of the mine, all of Precambrian age, are a series of gneisses and form a part of a great area of what are known as the Kisseynew gneisses. The Sherritt is the only known economic base-metal deposit to occur within the Kisseynew series. Extreme metamorphism has produced recrystallization that has imparted a decided igneous-like texture to many of the units. However, the gneisses are predominantly of sedimentary original although the most basic member, a hornblendegarnet gneiss, is considered to be an altered basic flow. Figure 1 illustrates the intricately folded structure and the succession of roe types. The footwall enclosing members are of sedimentary origin and represent quartzite and arkosic and greywacke derivatives. The contact footwall member is gneissic quartzite, a medium to coarse grained rock composed mainly of quartz with minor altered feldspar (orthoclase and plagioclase), muscovite, chloritized biotite, and magnetite. Most phases of this unit show varying degrees of granitization.

Jan 1, 1949

By J H. Dressel, J. E. Williams

This paper presents a brief review of what coal gasification is, procedures that are available today and processes that may be available in the future. Examples are given as to how the process might be used in power plant applications, the effect on pollution level and power costs, and some thoughts on the added burden that might be placed on mining and coal preparation.

Jan 1, 1973

By P .. H. Grimley, N. Champigny

"Fourteen companies (Appendix) representing senior mining organizations in Canada were canvassed in order to assess: (1) the current usage and trends, and (2) the usefulness of computer applications in ore reserve estimation and grade control. The results of the questionnaire suggest that:• computers are unsurprisingly, predominant in the mining industry for calculating reserves and performing grade control;• time and cost savings are realized;• computer-based approaches are applicable to underground situations;• geological information is incorporated to the computerization process; and• computer usage does not hinder the collaboration of geologist and mining engineer.A clear need is identified for case histories comparing computer-calculated ore reserves and actual production data.IntroductionAmong the management and technical staff of some mining companies there is a perception that the application of computer based technology for the estimation of ore reserves and grade control, has as many drawbacks as benefits. Some of the objections raised against the utilization of computers for ore reserve estimation are that:• computer-based reserve models work for large open pit mines but not for underground situations;• computer-generated reserves ignore the geologist's knowledge base; they are strictly a number crunching exercise; and• the use of computers for ore reserves hinders collaboration between the geologist and mining engineer.In order to determine (I) the extent of current computer usage and future trends and (2) whether the objections noted above are borne out by experience, a number of senior Canadian mining companies were canvassed.The respondents were asked to provide:• an assessment of the importance of the computer in the ore reserve estimation and grade control process;• the level of involvement of individuals and staff groups with computer-based ore reserve estimation;• the advantages perceived and realized from the utilization of computer-based ore reserve approaches;• the current and future human resources requirements for the evaluation, implementation, maintenance and development of computer-based ore reserve systems;• the hardware and software resources presently used and planned; and• the developments needed to increase the use and acceptance of computer-based ore reserves."

Jan 1, 1990

ONE of the morning sessions at the recent Annual Meeting was devoted to a Symposium on ways and means to expedite geological investigation, and also to promote greater prospecting activity, in Canada. It will be recalled that at the 1940 Annual Meeting, held in Winnipeg, a paper(l) prepared by Dr. G. A. Young, Chief Geologist of the Geological Survey, was presented, and was followed by a Symposium on Geological Investigations in Canada(2). On that occasion, the participants were in the main geologists, and they included the directors or other officials of each of the Provincial departments or bureaus of mines. At the Montreal meeting, the subject was discussed mainly from the point of view of the mining industry. The following pages present, in somewhat summarized form, the several contributions to that discussion.-ED. DR. J. J. O'NEILL(3), who was to have opened the Symposium, was unfortunately prevented through illness from attending the meeting. He had intended outlining the main features of his paper on The Exploitation and Conservation of Mineral Resources in a Balanced Development of Canada, presented at the last annual meeting of the Royal Society of Canada( 4). In his absence, DR.J. A. DRESSER presented a summary of the paper.

Jan 1, 1941

By Bruce Peberdy

Outline ?Building Systems ?Climatic Effects ?Thermal Effects ?Building Components ?Building Materials ?Structural Deterioration ?Maintenance Considerations

Nov 1, 2011

By J. S. Fox

Major-element data for unaltered, unmineralized felsic host rocks from a number of stratigraphically simple, massive volcanogenic Zn-Cu(-Pb) sulphide deposits of low metamorphic grade have been compiled. The petrochemical affinities of these host rocks have been determined (by standard means and by discriminant analysis) and compared. This comparison indicates that volcanogenic deposits in felsic terrains are not restricted to the classical calc-alkaline rock association as previously thought, but can actually be hosted by rocks showing a range of iron content. There is a positive correlation between differentiation trend and are tenor. Zn-Cu ores usually have iron-rich felsic hosts (most Canadian Shield deposits); Pb-Zn -Cu ores have iron-poor felsic hosts (Japanese, Iberian and Tasmanian deposits). This parallels the antipathetic relationship between iron content and background lead levels evident in young, unmineralized, island arcs as well as in many older belts. Correlations between differentiation trend on one hand and massive ore mineralogy and the relative proportions of various rock type (including rhyolite, quartz-porphyry and coarse pyroclastic rocks) on the other are also evident. It is concluded that the recognition of a calc-alkaline differentiation trend cannot be used as a prospecting guide, as has previously been proposed. However, in view of the above correlations, the recognition of a given trend may aid in the formulation of an effective exploration philosophy.

Jan 1, 1979

By Wenxue Chen

This paper presents a new type of bolt with full thread and uniform strength, and fabricated with a Glass Fiber Reinforced Polymer (GFRP) bolt-making machine designed by the authors. The mechanical performance of the new bolt is assessed with strength tests conducted with the bolt in acid, alkaline and saline water conditions, with increasing concentration. The purpose is to test the new GFRP bolt?s mechanical performance in harsh conditions, especially metal mines with acid or alkaline environments. Comparison of the color, weight, size and antistatic ability of the GFRP bolt before and after it is immersion in solution is presented. Changes in tensile and shear strength, torsion, and anchoring force were evaluated in the laboratory. The results show that the mechanical properties of the GFRP bolt are more sensitive in alkaline than in acid and saline water. However, the loss ratio of mechanical properties of the GFRP bolt is very small according to the results of tensile and shear strength, torsion and anchoring force. The new bolt can be useful for applications in acid or other harsh mines.

Aug 1, 2013

By R. Howard

"In projects involving resource development and plant optimization, the use of in-mine geophysics can deliver considerable benefit. The value proposition lies in using very high resolution downhole measurements to model process-plant outcomes. The calibration procedure used to convert in-situ physical properties into process engineering parameters is illustrated using two iron ore projects. Data correction was related either to orebody structure or mineral formation. The deliverable from this approach is a series of high-definition sections indicating the variability of ore delivered to a front-end separation plant and parameters for mine scheduling and stockpile design needed for maximum product yield.RÉSUMÉ Dans des projets de développement des ressources et d’optimisation de l’usine, l’utilisation de la géophysique minière peut engendrer des bénéfices considérables. La valeur de la proposition réside dans l’utilisation de diagraphies à très haute résolution afin de modéliser les résultats de l’usine de traitement. La procédure d’étalonnage utilisée pour convertir les propriétés physiques in situ en des paramètres d’ingénierie de procédés est illustrée en se basant sur deux projets de minerai de fer. La correction des données porte sur la structure de la masse minérale ou de la formation minérale. Les livrable attendus de cette approche sont une série de sections à haute définition, signalant la variabilité du minerai livré à une usine de séparation de première ligne, des paramètres pour l’échéancier de la mine et la conception des haldes requis pour une production optimale."

Jan 1, 2016

By J. R. Gordon

I-Introduction The possibility of adapting low-temperature reduction methods to the treatment of iron ores has been suggested on numerous occasions. Papers published on the subject include, notably, Bulletin 270 of the United States Bureau of Mines on The Production of Sponge Iron, the Symposium of the American Electrochemical Society (1927) on The Gaseous Reduction of Ores and Other Metallic Compounds, and Les Procédés Actuels de Traitement Direct du Minerai de Fer, by A. Mayer (Revue de l'Industrie Minerale, Nov. 15th, 1932) (1). The present paper contains the results of an investigation of the reducibility of some Ontario ores. The concentration of these ores and of the products of reduction has also been investigated.

Jan 1, 1933

By Xiong Tong, Jiushuai Deng, Yingbo Mao, Lingyun Huang

Ammonium carbamate has been used as a reagent for the leaching of copper from the copper oxide ore found in the Honghe state, Yunnan province, China. In order to find the optimal conditions for the leaching of copper from this copper oxide ore,the effects of several processing parameters, including the concentration, time, temperature, particle size and stirring intensity have been investigated. The results of these optimization experiments showed that the leaching rate of copper reached up to 72.76% under the following conditions: liquid-to-solid ratio of 10:1, ammonium carbamate concentration of 2.5mol/L, leaching temperature of 45 °C, stirring speed of 300rpm, a reaction time of 1.5 h and 85% by weight thereof passes through a sieve having 0.074 mm.

Jan 1, 2015

By Qin-yong Ma, Jing-shuang Zhang, Bo Han, Pu Yuan

In order to improve the utilization rate of blasthole and blasting effect in vertical shafts, 5 kinds of millisecond blasting model tests with three circle vertical blastholes have been conducted in various delay times with concrete as model material. The blasting effects of millisecond blasting model tests are investigated from cutting volume, cutting depth, and blasting fragmentation, then a reasonable delay time is obtained. In the middle of concrete model, there are 4 blastholes uniformly distributed in the first circle, 6 blastholes uniformly distributed in the second circle, and 10 blastholes uniformly distributed in the third circle. Each blasthole is charged with one millisecond delay electric detonator, and the rest is blocked with stemming. The depth of blastholes in the first and second circle is 180mm, which is 20mm deeper than those in the third circle. After initiation, the blasting cavity is cleaned up, then the cutting volume and cutting depth are measured. Meanwhile, the blasting fragments are gathered and have analysed by function Rosin-Rammler. The test results show that when the inner two circle blastholes initiated simultaneously and the third circle blastholes initiated with millisecond delay, the reasonable delay time is 50 ms. At this time, the cutting volume and cutting depth of blasting model are 3920 cm3 and 68 mm respectively. The fragmentation indexes of blasting fragments, X50 and X80, are 53.2 mm and 74.6 mm respectively. While when all three circle blastholes initiated with millisecond delay, the reasonable delay time is also 50 ms. At this time, the cutting volume and cutting depth of blasting model are 10705 cm3 and 118 mm respectively. The fragmentation indexes of blasting fragments, X50 and X80, are 51.0 mm and 81.7 mm respectively. The researches indicate that for millisecond blasting with multiturn blastholes, the reasonable blasting scheme is multiturn blastholes initiated in millisecond delay and the reasonable delay time is 50 ms.

Jan 1, 2015

By D. M. Muir

Many plants produce iron(II)/(III) waste liquors which must be treated by neutralisation and precipitation to remove the iron. Iron can be precipitated as crystalline goethite or jarosite by controlled oxidation at low pH and as magnetite by controlled oxidation at high pH, but only at elevated temperatures (>70°C). This study focuses on the characterisation and settling properties of the iron oxides produced at ambient temperatures using various neutralising agents in order to improve the performance of thickeners. It was found that two-stage addition of caustic to FeC12 solutions produced a fast settling material characterised by Mossbauer spectroscopy and XRD as maghemite and magnetite. However, lime and magnesia additions resulted in more ferrihydrite formation and much lower settling rates because of the enhanced oxidation of Fe(II) by air. Settling rates decreased significantly as the proportion of Fe(III) to Fe(II) in the liquor increased. The mechanism of iron oxide precipitation is discussed together with some reasons for the different behaviour of the neutralising agents.

Jan 1, 2006

By Z. S. Shao, X. Z. Li

"Sub-critical crack growth plays an important role in long-term creep failure in brittle rock. Based on micromechanics established by using relationship between micromechanical wing crack growth model and macroscopic strain, and comparing theoretical model with testing results, a method, which applies the theory to real rock, is suggested in this paper. Using this method, properties of creep, damage and progressive failure in brittle rock are investigated. Effects of stress state on creep failure time and steady-state creep rate are analyzed and graphically presented. The results are helpful to support structure design and service life evaluation of underground structures with high geostatic stresses. INTRODUCTIONDuring the long-term operation in underground space with brittle surrounding rock, due to chemical action between pore water and rock, the failure of rock often occurs at stresses below its short-term failure strength, which brings serious effect on the long-term stability of underground structure. Thus, the long-term strength of brittle rock attracted wide interests of scholars around the world. The static fatigue limit was predicted by exponential function that is derived from abundant experiment data of stress level and failure time(Schmidtke & Lajtai, 1985), and similar result by relationship between stress state and failure time was also suggested (Lau & Chandler, 2004; Aubertin et al., 2000; Sangha & Dhir, 1972). According to relationship between steady creep rate and stress state during creep, a critical stress that transforms steady-state creep to accelerated creep was studied and the long-term strength was suggested (Tsai et al., 2008; Ma & Daemen, 2006; Lajtai et al., 1991). Based on the results of experiment in compression, the long-term strength of rock was defined by stress at volume strain reversal. When applied stresses are larger than the long-term strength, the microcracks in the rock will grow constantly, damage of rock will increase and failure of rock will occur finally (Chandler, 2013; Bieniawski, 1967; Brace et al., 1966)."

Jan 1, 2015

By H. J. McQueen

Pressure welding is a solid state joining technique that depends on bringing the parts into sufficiently close contact that inter-atomic bonds are achieved. Pressing is more effective at elevated temperatures where plastic flow causes the asperities to collapse; improved application conditions are derived from hot-work research to clarify temperature and strain rate dependence of hot strength and ductility. The substructure evolution systematically studied in hot working to determine dynamic recovery or recrystallization is applied to clarifying that developed in welding. The various processes are affected differently by work-piece geometry and final shape requirements. In addition to pre-cleaning of the surfaces, the plastic flow helps disperse the remaining oxide layers as was originally exemplified in blacksmith hot forging of layered sword blades and in bellldie welding of wrought iron tubes. The presentation critically compares the utility for various materials and configurations of simple pressure, ultrasonic application, diffusion, explosive, rotary and linear friction and friction-stir processes. Diffusion bonding (primarily Ti) with light cleaning, low pressure, little distortion in protective furnace atmosphere contrasts strongly with the heavy upsetting in friction welding, or complex alloy mingling and substructure variations in friction stir joints.

Jan 1, 2011

Mineral resource development activities impact the health and well-being of many people, from workers, to families and surrounding communities. In the decade up to 2010, mining revenues increased from 6% to 14% of Australian GDP, and minerals contributed 55% of total exports, with a growth in mining employment from 1% to 1.7% of the national workforce (Connolly and Orsmund, 2011). The growth in Australia?s minerals operations is mostly located in remote areas, or in rural communities with a limited population. As a result, operations have increasingly implemented long distance commuting (LDC) programs, often called ?fly-in, fly-out? (FIFO) and ?drive-in, drive-out? (DIDO), as a staffing strategy to meet rapid industry growth in locations with limited local populations. The rapid expansion of the minerals industry has resulted in considerable public debate about the benefits and costs to all sectors of Australian society. In response to the concerns of constituencies from many parts of Australia, the Minister for Regional Australia, Regional Development and Local Government, The Hon Simon Crean MP, asked the House Standing Committee on Regional Australia on Tuesday 23 August 2011 to inquire into and report on the use of ?fly-in, fly-out? (FIFO) and ?drive-in, drive-out? (DIDO) workforce practices in Regional Australia. The recently published report highlights the national interest and the diverse opinions about this practice in Australia. Resource extraction companies have developed several options to meet the accommodation requirements of their long distance commuting workforce. In this paper, initial results are reported from an ongoing survey of FIFO (and other non-residential) resource industry workers (n = 286) in the Australian resource extraction industries. The purpose of this study was to better understand how accommodation arrangements may impact on the health, wellbeing and job satisfaction of non-resident workers; and to attempt to find a relationship between different accommodation variables and workforce wellbeing and retention. In doing this it investigates evidence for the linkage between accommodation factors, hours of work, health, well-being, job satisfaction and job retention in the LDC work force.

Aug 1, 2013

By J. D. Bateman

DURING the summer of 1942 several chromite deposits were discovered in the Lac du Bonnet district about eighty miles northeast of Winnipeg. The deposits are confined to the Bird River complex, a folded composite sill of basic and ultrabasic igneous rocks of early Precambrian age that lies to the north of Bird river (1). The outcrop of the sill represents the trace of an easterly plunging anticline, the south limb extending from the northeast bay of Lac du Bonnet eastward to Bird lake, and the other limb, 6 to 12 miles north, lying between Maskwa river and Euclid lake. The south limb of the sill is 20 miles long, and the northern counterpart 15 miles; but its continuity is interrupted by faulting and by the intrusion of younger granite, so that the total length of outcrop of both limbs does not likely exceed 25 miles. The sill is intrusive into early Precambrian greenstones and associated sedimentary rocks. The chromite discoveries have been made at several localities on both limbs of the sill, and in each case at the same geological horizon. The sill comprises an upper layer of hornblende gabbro and a lower layer of serpentinized peridotite, and altogether is from 500 to 3,500 feet thick. The chromite zone is within and near the top of the peridotite layer, and thus about midway of the sill, both of the limbs of which stand nearly vertical. This geological relationship was established early in the exploration of the initial discoveries and served as the basis for successful predictions of later discoveries. The chromite zone probably persists throughout the length of the sill, but its width and chromite content are not everywhere the same. The initial exploration along both limbs of the sill has shown a combined total length of about 12,000 feet of chromite ore varying in width from 6 to 12 feet. In many places the overburden is thick and obscures the continuity of the chromite zone; but as investigation proceeds the known deposits will be extended and new ones will be found. Thus, although a total length of 12,000 feet of ore has been investigated up to the present time, there is an indicated length of approximately 31,000 feet along which the ore is more than 4 to 5 feet wide. This estimate is based on geological considerations and represents a total tonnage in the order of 15,000 tons per vertical foot of depth.

Jan 1, 1943