Search Documents

By A. R. Sheik, A. A. Baba, M. K. Ghosh, K. Sanjay, R. B. Bale, A. G. F. Alabi, F. A. Adekola, L. Ibrahim

"This paper studies the characterization and dissolution of a Nigerian pyrolusite ore, reporting the results of ore physicochemical analyses and detailed ore characterization before and after leaching at optimal conditions. Ore dissolution rate increased proportional to acid concentration and temperature, but decreased with ore particle size. In a 4 M H2SO4 solution at 80°C with a particle size of –90+75 µm and moderate agitation, ore dissolution rate reached 78.7%. Unleached residue produced under optimal leaching conditions consisted of silica with admixtures of cristobalite and stishovite. The calculated activation energy supported the proposed diffusion control mechanism for the process.RÉSUMÉ Le présent article étudie la caractérisation et la dissolution d’un minerai de pyrolusite du Nigeria, il donne les résultats des analyses physicochimiques du minerai et de la caractérisation détaillée du minerai avant et après la lixiviation sous des conditions optimales. Le taux de dissolution du minerai augmentait proportionnellement à la concentration de l’acide mais décroissait avec la taille des particules. Dans une solution 4 M H2SO4 à 80 °C, avec une granulométrie de –90+75 µm et une agitation modérée, le taux de dissolution du minerai a atteint 78,7 %. Les résidus produits sous des conditions optimales de lixiviation étaient constitués de silice avec un mélange de cristobalite et de stishovite. L’énergie calculée d’activation supportait le mécanisme de contrôle de la diffusion proposé pour le procédé."

Jan 1, 2016

By J. Cayouette, C. Bolduc, P. Blatter

"The LaRonde mill was commissioned in 1988 and began treating ore from the Penna shaft in 2000. The mill has been expanded to accommodate 7,500 t/day, but ramped down to 6,000 t/day since the deep extension began. The process recovers gold, silver, and base metals. In 2008, the Goldex plant began trucking gold-pyrite concentrate to a treatment plant feeding pulp to the LaRonde mill, increasing gold output by 40,000 oz. In 2009, the high-grade Lapa ore processing facilities were annexed to the LaRonde plant, increasing gold output by 120,000 oz. This paper outlines the metallurgical considerations related to the treatment of different ore types.RÉSUMÉ Le concentrateur de la mine LaRonde a été mis en service en 1988 et a commencé à traiter le minerai du puits Penna en 2000. La capacité du concentrateur a augmenté afin de permettre le traitement de 7 500 tonnes de minerai par jour, capacité qui est retombée à 6 000 tonnes par jour (tpj) depuis le début de l’extension en profondeur de la mine. Ce procédé permet de récupérer de l’or, de l’argent et des métaux communs. En 2008, l’usine de traitement Goldex a commencé à transporter par camion du concentré de pyrite et d’or vers une usine de traitement alimentant en pulpe le concentrateur de LaRonde, augmentant ainsi la production d’or de 40 000 onces. En 2009, les installations de traitement du minerai à haute teneur de Lapa ont été annexées à l’usine de traitement de LaRonde, augmentant la production d’or de 120 000 onces. Cet article passe en revue les considérations métallurgiques liées au traitement de différents types de minerai."

Jan 1, 2017

By Chunfeng Zhao, Chong Bao, Cheng Zhao, Jiashen Tian, Matsuda Hiroshi

"Based on digital image correlation (DIC) method and self-developed code, the global strain field changing and failure properties of rock-like materials with pre-existing double flaws are experimentally studied under uniaxial compression. By theoretical analysis with linear elastic fracture mechanics (LEFM), the strain approach proves to be practicable to investigate cracking process. Thus, two types of process zone are defined to discuss the specimen’s coalescence evolution at different loading stages. Crack initiation, propagation, and coalescence is a process of zone development and nucleation. DIC strain field results are studied on a meso-level using a strain approach. In the shear coalescence mode, the SPZ (shear process zone) in a bridge area coalesces with each other, while the TPZ (tensile process zone) grows independently. In general, the paper tries to establish the link between microscopic mechanical mechanisms and macroscopic mechanical responses in flawed rock. Further research should be done to study the cracking process and its effect on rock strength in detail by the DIC method.INTRODUCTIONNatural rock contains discontinuities including pores, fractures, inclusions or other defects. The existence of these discontinuities in the rock can decrease the strength and stiffness of the rock and they are a source of initiation of new discontinuities which may in turn propagate and link with other cracks and further decrease the strength and the stiffness of the rock (Sagong & Bobet, 2002). Lots of theoretical, experimental and numerical researches have been done in studying crack initiation, propagation and coalescence in rocks (Hoek & Bieniawski, 1965; Kranz, 1983; Reyes & Einstein, 1991; Park & Bobet, 2009; Gonçalves & Einstein, 2013). But when it comes to multiple pre-flaws, the issue that how the preexisting flaws affect each other becomes complicated and uncertain. The stress field around the tips of flaw can either enhance the impact of single flaw or weaken it. According to the observations have been done before, it is found that the way and function in which these cracks propagate and coalescence depends on the geometric arrangements (Bobet, 1997; Bobet & Einstein, 1998; Wong & Chau, 2001)."

Jan 1, 2015

By James W. Cameron

DESPITE the fact that, after oxygen and silicon, aluminum is the most abundant and widely distributed element in the earth's crust, it is, commercially, a modern metal. Attempts were made by Sir Humphrey Davy and other chemists to decompose alumina, the oxide, into its elements, but with unsatisfactory results, and it was not until 1827 that Wohler succeeded for the first time in isolating the metal in pure form. Some thirty years later, commercial production of aluminum was started in a plant near Alais, France, using a process developed by Deville which was a modification of that of Wohler. It was not, however, until around 1886 that possibilities of low-cost production were realized. Hall and Heroult discovered, independently, the now famous process for extraction of aluminum by the electrolysis of alumina (Al,O,) dissolved in fused cryolite. This discovery, with its subsequent effect in reducing the price of the metal, was perhaps the greatest single factor contributing to the remarkable growth of the aluminum industry. But only in the years following the Great War did aluminum begin to attain equal importance in many fields with other non-ferrous metals. Numerous factors, political and economic, in the past decade have had a profound effect on the industrial history of the metal. At present, systematic substitution of aluminum for other base-metals is proceeding at a rapid rate in such countries as Germany and Italy with a view towards 'economic self-sufficiency'. Quite naturally, ?the economic depression started extensive research and experiment in various industries in an attempt to improve efficiencies and lower costs. Partial answers have been found in the extended use of aluminum and its alloys. Even against the background of tremendous technological advance that has marked the past fifty years, the rise of the aluminum industry must necessarily stand out conspicuously.

Jan 1, 1939

By A. Manohar Rao

Underground mining in general and more so the coal mining is a hazardous venture as it is a struggle against nature and natural forces. The stability of roadways has a direct impact on production and productivity. The roadway stability can be strongly influenced by the direction of the drivage. The stress studies are useful to provide a frame work for understanding the influence of drivage direction on roadway conditions, and to illustrate how mapping techniques can enhance this understanding. The act of mining can concentrate and re-orient the original stresses. Whenever coal is removed, the overburden weight that it carried is transferred. Vertical stresses are similarly affected when the roof is deformed or failed. The Singareni Collieries Company Ltd., a joint Public sector undertaking of the Government of Andhra Pradesh and India is conducting coalmining operations in the Godavari Valley Coalfield and is catering to the needs of a large part of South India. With the technology update, it is looking for safe mining and to achieve higher production. As a part of this, an attempt is made to understand the stress conditions prevailing on the mine blocks by different ways and means in terms of geology, structure and tectonics of the Godavari Valley coalfield, satellite imagery studies, cleat pattern, stress measurement studies conducted in different mine blocks, and stress mapping technique.

Aug 1, 2013

By M. Härting, D. T. Britton, M. Nzikou Mamboukou

"Copper containing different types of nanocomposites have been characterized for nanolabelling and ID. Three types of the rare earth nanoparticles were used for this study, the oxide and the sulphur compound of the Eu and Tb. Characterization techniques uses SEM, and Raman for morphology, chemical composition, and optical characterization respectively. It has been shown that it is possible to include the rare earth particle in a copper matrix without damaging its physical properties. INTRODUCTIONThe development of new materials, often involves the addition of new properties without changing the beneficial properties of the original material (Chen et al., 2009; Khana et al., 2007; Patil et al., 2008). Nanocomposites are nanostructured materials, whose structural elements including clusters, crystallites or molecules, of dimensions ranging between 1 to 100 nm (Moriarty, 2001), or a composite material where one of the phases is a one, two or three dimensionally nanostructured material (Nanotechnology, 2006; Wang, 2001). Nanocomposite materials research is a fast growing area due to the high demand for materials for specialized applications (Edelstein & Cammarata, 1998), such as biolabelling, magnetic storage media, solar energy transformation (Jisen et al., 2004), and resistance welding applications (Bessergenev et al., 1997; Kwon et al.,2006).The properties of the nanocomposite materials depend not only on the properties of their individual parent materials, but also on their morphology and the interfacial characteristics. Thus, significant efforts have been focused on the control of the nanoscale structures via innovative synthesis approaches. Therefore, novel materials of unique properties may be obtained by combining properties from the parent constituents into a single material (Balan, 2006; Garcia et al., 2009). Possible effects of nanocomposites in the original material may include changes in the mechanical properties such as hardness , wear resistance (Rafaja et al., 1987), and electrical properties (Britton et al., 2003). The inclusion process may therefore be used to tailor materials to have particular mechanical, electrical and optical properties (Das et al., 2009). However, to fully understand the nanocomposite, it is necessary to study the fundamental properties of both the host matrix and the inclusions (Li, 2008)."

Jan 1, 2012

By Rodrigo Serna-Guerrero, Ted Nuorivaara

"As the demand of raw materials increases in a global scale due to demographic and economical changes, it is necessary to find technological solutions that improve current production processes in an efficient and sustainable manner. The main objective of this preliminary study is to evaluate the properties of foam produced with a cellulose-based molecule as an alterative to commercial frothing agents in flotation operations. There are two potential advantages identified with the use of cellulose-based additives for the proposed application: i) these chemicals can be produced from sustainable sources (i.e., non-edible crops), and ii) cellulose can be functionalized with chemical groups, in order to rationally modify its behaviour. In previous studies dealing with foam stabilization, it has been proposed that some functionalized cellulose species present a self-assembly mechanism at gas-liquid interfaces. Unlike typical surfactant-based frothers, cellulose molecules form networks around the bubbles that act as protective layers to the mechanical stress and to the occurrence of ionic species. This work studied the properties of foams produced in the presence of a partially hydroxylated cellulose molecule (i.e., hydroxypropyl methyl cellulose; HPMC) under various concentrations in a laboratory-scale column. A comparison with a commercial surfactant frother (i.e., Nasfroth 240) is presented, and a rationalization of the behaviour of HPMC in terms of foam properties (i.e., surface tension, bubble size, foam depth) is proposed. INTRODUCTIONThe search for green alternatives to chemicals produced from non-renewable sources has become a topic of major relevance in industry (Choi et al., 2015). As a chemical consuming industry, the mining sector faces now the challenge of adopting new processing technologies and strategies in order to achieve the future demands of sustainability. Evidently, a move towards green chemistry can only take place by identifying substitute molecules offering potential advantages in terms of recovery and grade."

Jan 1, 2016

By G. C. Hambleton

"The author has had wide experience in the reclamation of coal from coal mine waste dumps in the United Kingdom.The paper includes such topics as the processing decision and factors affecting processability; method of testing and appraisal; test data interpretation; historical influences in apppraisal; special contaminants and processing difficulties; methods of treatment; review of systems in use and their comparative economics; over-all system economics including excavation, handling methods, recovery system and shale disposal; effluent treatment; environmental considerations; alternatives to processing for coal recovery; light aggregate and cement usage; burned shale heaps; land reclamation; shale deposition for encouragement of vegetation by natural or artificial means; use of tailings fines; the environmental argument for action."

Jan 1, 1972

By S. M. Grillo, Fiori. M., R. Bornioli, C. Marini, S. Fadda

Abstract - The Na-feldspar orebodies in Sardinia occur along structures belonging to a regional ENE-WSW system that developed during the late stages of the Hercynian orogeny, and that was reactived during the Alpine orogeny. The main petrographic facies include granitoids, albitized granitoids, albitites (more or less rich in quartz), and albitites containing Mg minerals. Field observations and petrological and geochemical data point toward a metasomatic origin for the albitite orebodies. Albitization involved depletion of K from K-feldspar and biotite, dissolution of free quartz, and a lowering of Sr/Na2O and CaO/Na2O ratios in the protolith, under conditions of a positive thermal gradient. The absence of later K-metasomatism implies that, during a subsequent decline in temper- ature, the composition of the albitizing fluids was modified by an influx of meteoric or other waters.

Jan 1, 1996

By F. Calizaya, S. Bhattacharyya

"This study presents the results of a set of sound level measurements carried out in three underground mines where auxiliary fans are used regularly. Sound levels as high as 100 dB(A) by the workings and 115 dB(A) by the fans were measured in these mines. These levels are quite high even for intermittent noise. Ventilation layouts and best practices used to overcome potential problems related to overexposure to fan noise in underground hard-rock mines are presented here. Factors such as fan type, rotational speed, and silencer-duct arrangements and their effects on noise attenuation are discussed. INTRODUCTION Auxiliary fans are used in hard-rock mines extensively. They are used to ventilate development headings, crusher rooms, conveyor transfer points, and underground shops. They are also used in developing long tunnels and ramps. Depending on the flow requirements and space restrictions, single or double stage axial fans with rigid or flexible ducts are used. Usually, they are high pressure (3.75 kPa) fans with flow rates ranging from 7.1 m3/s to 30 m3/s. The input power varies from 15 kW to 113 kW (Mutama, 2004; O’Connor, 2008). Typically, a 113 kW fan can produce sound levels as high a 113 dB(A) (Howes, 2005). Silencers are often omitted for cost reduction purposes or when used, they are not well maintained. Furthermore, silencers provide limited attenuation depending on their length and type. Typically, the sound attenuation ranges from 10 dB(A) for a 1 × D silencer to 14 dB(A) for a 2 × D silencer, where D is the fan diameter. In a mine, the silencer is subject to wear and tear, especially when the silencer is used in harsh environments. The interior lining can get clogged and the acoustic fill can get covered by dust and diesel soot, thus reducing the silencer performance. Periodic cleaning of the interior casing can increase the attenuation capacity of a silencer by 6 to 9 dB(A) (Dabson & Acuña, 2017). However, this requires a special silencer design in which the inner cartridge can be removed, the sound absorbing material replaced, the inner casing cleaned and the whole set retrofitted. A number of techniques can be used to reduce auxiliary fan noise in underground mines. These range from selecting the right fan for the job to installing adequate silencers. The choice depends on the air quantity requirement at the working place, cross-sectional area of the opening, duct diameter, fan type (axial or centrifugal) and local restrictions. Auxiliary ventilation layouts and best practices used to overcome potential problems related to overexposure to fan noise in underground hard rock mines are presented here. Factors such as fan type, rotational speed, duct diameter, and silencer-duct arrangements and their effects on noise attenuation are discussed."

Jan 1, 2019

By S. Kursunoglu

The aim of this study was to investigate the effectiveness of Ascorbic (C6H8O6) Acid (AA), Activated Carbon (AC) and Guar Meal (C6H12O6) (GM) as a reductant for the simultaneous complete dissolution of zinc (Zn) and manganese (Mn) from a spent and mixed Zinc-Carbon (Zn-C) and alkaline battery powders in sulphuric acid (H2SO4) leaching. AA was tested previously as a reductant by other researchers while AC and GM were tested as a reductant for the first time in battery recycling. The effects of H2SO4 concentration, AA/AC/GM dosages, reaction temperature and leaching time on the Zn and Mn dissolutions were investigated according to 2k full factorial experimental design and Central Composite Design (CCD) technique; then, a simple optimization study was carried out for comparing the reductants. The optimum reductive acid leaching conditions for AA were determined at 3 hours leaching time, 70°C leaching temperature, 0.5M H2SO4 concentration, 13 g/L AA dosage, 1/20 g/mL solid/liquid (S/L) ratio and 200 rpm stirring speed. Under these conditions, the dissolution efficiencies were 99.9% for Zn and 99.3% for Mn. The best reductive acid leaching conditions for AC were determined at 3h leaching time, 80oC leaching temperature, 1M H2SO4 concentration, 3 g/L AC dosage and 400 rpm mixing speed. Under above conditions, Zn and Mn dissolutions were not complete. At 2M H2SO4 concentration, 10 g GM dosage, 700C leaching temperature, 200 rpm stirring speed, 1/20 g/mL solid/liquid (S/L) ratio and 3 hours leaching time, full dissolution of both Zn and Mn was achieved. As a result, three different reductants were evaluated in this study for complete simultaneous Zn and Mn dissolutions. This paper also compared present test results with previous spent battery recycling studies for Zn and Mn dissolutions. Full valuable metals dissolutions from spent batteries were achieved at low H2SO4 concentrations with AA and high concentrations with GM. Selective precipitations of Zn and Mn from acid solutions were carried out using NaOH and KOH. Using 3M NaOH as precipitating agent at room temperature and at pH 8; 95.4% of Zn and at pH 10; 93.7% of Mn were precipitated from the leach solution. Under the same conditions, using 3 M KOH at pH 8; 91.6% of Zn and at pH 10, 96.4% of Mn were precipitated. Based on the experimental results obtained, an appropriate flow sheet was proposed to recover both Zn and Mn.

Aug 1, 2013

By J. G. Whellock, J. W. Matousek

"In spite of their importance to the economics of many metallurgical projects, the values and technical aspects of precious metals losses in smelting operations are relatively undeveloped subjects. This paper attempts to provide a condensed overview of precious metals losses in pyrometallurgy, using some of the limited production and experimental data available. It is intended for three general groups of metallurgists - operators attempting to improve recoveries, cost-accounting engineers making estimates of metal losses in new or modified smelting plants, and research engineers and students.Distribution coefficients of precious metals, the ratios of metal or matte assays to slag assays, are convenient means of comparing smelting processes and the tendencies of the different metals to enter the slag. For silver in lead blast furnaces this ratio is approximately 250;for gold and the platinum group metals in submerged-arc, electric furnaces it is 900. The ratio for gold and PGMs in converters varies with the degree of oxidation of the charge. The over-all cycle-average for industrial installations is tentatively estimated to be 35.IntroductionThe magnitude of precious metal s losses in pyrometallurgical operation s is difficult to assess. The primary producers are generally reluctant to discuss the subject. The by-product producers (the large sulphide smelters o f copper , nickel, and lead) might be more willing to disclose information, but these have precious metals in their feeds in such dilute quantities that accurate accounting is extremely difficult. It is not until numerous processing steps have been taken t hat the precious metals become sufficiently concentrated to permit acceptably accurate sampling and analytical procedures to be followed. Thus, knowledge of the precious metals contents o f the intermediate mattes and slags may simply be unavailable."

Jan 1, 1990

By Raj K. Rajamani, Nikhil Dhawan

"Agglomeration has become common pre-treatment step to improve heap leach percolation thereby recovery, the fundamental understanding of the agglomeration process for crushed ores is still lacking. Agglomeration is required for ores which either contain excessive amounts of clay or an excessive quantity of fines generated during mining and crushing. Numerous experiments have been carried out in laboratory scale batch drums using different ores. It has been found out that experimental agglomerate size distributions exhibit self-preserving spectra. The self-preserving/ similarity distribution of the agglomerates is found to be independent of operating conditions and is uniquely determined by the size enlargement mechanism. An empirical model based on the absolute difference between moisture applied and optimum moisture was developed. This model uses self-preserving spectra in the form of a Rosin-Rammler distribution function to predict size distribution at different operating conditions. The empirical model was considerably easier to work with plant scale agglomeration drums. Also, a test known as dip test is developed which improves fundamental understanding of the agglomerate formation and growth mechanisms. This test also provides the progeny size distribution of each agglomerate size. The progeny size distribution was analyzed with a model that partitions the particles into a host and guest category. The ensuing partition coefficient identifies the behaviour of a particle as a host for other particles or a guest layering on other particles. This concept helps in identifying the type of agglomerate that would result for a specific feed size distribution. INTRODUCTIONHeap leaching is one of the hydrometallurgical processes that have served as a green and economically viable process for the treatment of low grade complex ores of copper, uranium, nickel, silver and gold (Dhawan et al., 2013). Heap leaching appears to be a favorable candidate for the least energy consuming process for low grade ores. In heap leach operations nowadays a pretreatment step known as crushed ore agglomeration has been implemented (Dhawan et al., 2013). A bed of agglomerates improves the uniform percolation of solution through the heaps of ore. Therefore, it was possible to treat wastes and mill tailings via agglomeration and heap leaching. Agglomeration pretreatment is required for ores which either contain excessive amounts of clay or an excessive quantity of fines generated during mining and crushing (Bouffard, 2005; Dhawan et al., 2013).While agglomeration has become common practice pretreatment step in heap leach operations, the fundamental understanding of the crushed ore agglomeration process is still lacking. The author reviewed publications up to 2012 on the crushed ore agglomeration process and did not come up with modeling studies on the topic (Dhawan et al., 2013). Some of the possible reasons can be the stochastic nature of the process, experimental difficulties, and lack of instrumentation for fundamental studies."

Jan 1, 2016

By G. D. Mcdowell, L. B. Cochrane, B. D. Thompson

"Abstract - Exploration for deep underground copper and nickel sulfide deposits in the Sudbury mining camp is carried out with surface drilling. More detailed drilling, with an advanced underground exploration program, may be necessary to establish an accurate interpretation of the deposit geology and upgrade the resource estimate to the measured category for reserve estimation and feasibility assessment. Resource evaluation is a lengthy and costly process that could result in a decision not to proceed with the project. For projects that proceed to production, significant reductions in the operating and capital costs could be achieved with a more accurate interpretative model of the deposit geology and mineralization. Quality control procedures to ensure the integrity of the drilling data and interpretation guidelines are essential steps in the development of a deposit model. The use of block modeling techniques and the application of geostatistics for resource estimation further improve the quality of the resource model.Significant improvements to the interpretive models can also be achieved by incorporating additional information from geophysical measurements to validate and constrain the geological interpretation. The geophysical models must be consistent with known geological environments and oreforming processes, which has required the concurrent development of comparative models from exploited deposits. These geophysical techniques can also provide key geotechnical information required for the optimum design of the mining method and mining sequence. The objective of this program is to improve the accuracy of the deposit model and the quality of the resource and reserve estimates in order to optimize capital investments and reduce the development and operating costs of underground mining projects. Several of these techniques are currently being tested at INCO Limited’s Sudbury operations. The results from those tests are presented and their applications are discussed within the framework of resource/reserve classification systems and project evaluation objectives."

Jan 1, 1998

By H. Tan

The effect of carbonaceous matter on gold extraction was investigated in cyanide systems with pure gold as well as pre-robbing sulfide gold ores. Auger studies demonstrated that the carbonaceous matter preferentially smeared on iron sulfide rather than aluminosilicate surfaces during wet or dry grinding. During mechanically mixed leaching, coating of sulfides and silicates and stripping of carbonaceous matter occurred simultaneously. TEM and XPS studies indicated preferential coating in the form of elemental (graphitic) carbon at the edges and the defect sites of particles. Interestingly, carbonaceous matter extracted from the gold ore was predominantly graphite and not preg-robbing in a solution with a high KCN concentration. However, the carbonaceous coating had a significantly detrimental effect on gold dissolution when gold was pre-ground with the gold ore. Artificial coating on gold surfaces with the natural carbonaceous matter from the ore was also found to substantially retard gold dissolution. With the addition of the natural carbonaceous matter from the gold ore, gold extraction from two non preg-robbing sulfide gold ores was inhibited owing to carbonaceous coating. The presence of carbonaceous matter significantly reduced the current density for gold oxidation and increased the current density for pyrite oxidation. This could explain the fact that carbonaceous coating hindered gold dissolution while enhanced sulfide preg-robbing.

Jan 1, 2005

By Muhammad Zaka Emad

ABSTRACT: Sublevel stoping mining methods with delayed backfill employs cemented rockfill (CRF) as a backfill material. It is used in underground mines to achieve ground control and reduce wall slough. In addition CRF serves to reduce development waste and provides a working surface for mining the upper levels. Efforts to optimize CRF practices have been published. This paper presents a detailed review of CRF practices in open stoping mining systems with reference to case studies. A new methodology is suggested in a simple stepwise approach, which can be adopted for site specific conditions. The need of laboratory testing and quality control program is discussed based on the published literature.

May 1, 2013

By F J. Pearce

The Steel Company of Canada, utilizing the S-L process, has produced partially and highly reduced pellets for use in the blast furnace. Experimental blast furnace tests, using reduced pellet burdens, have been carried out. The changes in production rate, fuel rate and general performance of both the S-L and the blast furnace processes are indicated. Introduction T HE ore burdens for a blast furnace may be improved in two ways: chemically, by concentrating the ore to a high degree of purity; and physically, by agglomerating or closely sizing the ore particles. Today, many b1ast furnaces are charged with closely sized agglomerates, some of which contain upwards of 66 per cent iron. The further improvement of these burdens by chemical concentration may, in many instances, be uneconomic due to the large losses of iron that occur during processing. Assuming that it would be possible to reject all of the gangue minerals, the maximum level of concentration of iron in the hematitic ores would be only about 70 per cent.

Jan 1, 1964

By F. E. Goodwin

Since the last CIM Zinc and Lead Conference ten years ago, significant technical and market forces have influenced how these metals are used, and the geographic distribution of their uses. Unprecedented price fluctuations have opened competitiveness issues, while the rapid growth of the Chinese market has created challenges both inside and outside China. Recent technical developments in battery energy storage, coatings, castings and chemical applications of lead and zinc will be reviewed together with the influence of these trends on end use markets.

Jan 1, 2008

By Piotr Malkowski

Studies on the properties of rocks heated to high temperatures are rather rare. Such research is occasionally conducted for example; in areas around nuclear power plants. The national Polish coal gasification (underground coal gasification, or UCG) project has, however, forced the analysis of the geomechanical properties of heated rocks in the vicinity of a designed geo-reactor. Ukrainian experience with UCG show that rocks up to 2 m from the burned coal seam be at a temperature > 600ºC. Such a high temperature will undoubtedly influence their physical properties. This paper presents studies on the strength and deformation properties of carboniferous rocks in the Upper Silesian region, where the UCG process is planned. Three types of rocks were tested: claystones, mudstones and sandstones. Laboratory tests of these rocks evaluated compressive strength, elastic modulus and weight loss. An evaluation of the results of the tests comparing the thermal conductivity of rocks and their specific thermal capacity was then carried out. All of the rocks studied were heated to 300, 600 and 1000ºC, and also evaluated at room temperature. This procedure shed new light upon the behavior of heated rocks in relation to their distance from the designed geo-reactor. The test results presented were developed within Research Task No. 3 ?Developing a technology of coal gasification for efficient production of fuels and electric power?, financed by The National Centre for Research and Development under strategic research and development programme ?Advanced Technologies for Energy Generation.?

Aug 1, 2013

By Gordon A. Irons, H. Y. Hwang

An impinging gas jet on a water surface was studied to understand momentum transfer in oxygen steelmaking. Depth, width and oscillation frequency of the jet cavity were measured and the splashes interpreted with Kelvin-Helmholtz instability and combined Rayleigh-Taylor and Kelvin-Helmholtz instability theory. A model to calculate separate gas and liquid velocities, applying the exact momentum boundary condition, is proposed.

Jan 1, 2004