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By Stefan Larsson, Jan Ekström, Jennie Kock-Larsen, Håkan Garin

"This paper describes the testing procedure (or protocols) for quality control of dry deep mixing columns in a major ground improvement project carried out in Sweden. Quality control was mainly based on column penetration tests performed at different stages in the project and on two occasions after installation. In the paper, the results from the tests are compared with tests on the unimproved clay. As expected, the results show that the correlation between undrained shear strength in the columns and in the unimproved soft soil depends mainly on the in-situ stress. However, the correlation probably depends on when the tests were performed after mixing. When the influence of the in-situ stress was excluded from the analysis, no significant correlation could be identified. This means that the undrained shear strength in the columns and in the unimproved soft can be considered to be uncorrelated when the strengths and the corresponding variability are evaluated with depth from groups of tests.INTRODUCTIONQuality control and quality assessment of deep mixing (QC/QA) constitute a key component in verification of the limit state design. Due to the complex mixing process and varying geological conditions, it is normally not possible to sufficiently assess the strength and deformation properties in advance. In Sweden, the most commonly used QC/QA method for verification of the limit state is the column penetration test (Axelsson and Larsson 2003; Bergman et al. 2013). The method works well but is time-consuming and requires many tests since property variability is normally high. The column penetration test can be used to assess the undrained shear strength Cu,col. However, it is not clear how the strength correlates to the undrained shear strength of the unimproved soil Cu,soil. There are common factors such as the in-situ stress state and the natural water content, which makes a positive correlation probable, i.e. as Cu,soil decreases, Cu,col also decreases and vice versa. The unimproved soil has a natural spatial variability, but it is not known if the improved soil follows the same variation. The mixing process has a substantial influence on the strength variability and may supersede the influence of other factors. However, if a sufficiently good correlation exists between Cu,col and Cu,soil, information from the geotechnical ground investigations can be used in the design and planning of QC/QA of deep mixing in a more stringent manner. Information about the correlation is also essential in reliability based design, where a strong positive correlation may have a negative influence on reliability. However, as discussed by Al-Naqshabandy and Larsson (2013), this correlation may be weak or insignificant for a representative failure domain where the mixing process may have a dominant influence on the strength variability. It is thus of interest to assess the correlation."

Jan 1, 2015

By George T. Hansen

WHY try to find oil in Utah? Why try to find oil anywhere? Isn't there too much oil already? Answers to these questions involve general oil conditions but are pertinent to my subject. In the first place oil produced in Utah up to the total amount of local consumption would not be subject to nor concerned with the national oil situation. An oil field in this State capable of producing up to 15,000 bbl. per day would have a large value and prompt realization. In the sec¬ond place, there is not too much oil nationally although the markets have been upset temporarily from time to time. Petroleum is so necessary and is in such general demand that an oil field anywhere, anytime, is a valuable and live asset. The oil business in general shows the best condition of any major industry. It has never been hit as hard as most industries and 1932 was a large improvement over its low spot of 1931. It can be and probably will be the one to lead the country back into business stability. Consumption of its products has been reduced less than that of any other important commodity. There are good and valid reasons why it should have been making a normal profit continuously. It has the oil and the processes and the facilities and the policies and the consumption of its products. There is only one reason why it has not been profitable recently and that is the lack of intelligence of from five to ten per cent of the producers. An op¬erator lacks intelligence when he cannot see that it is better for him to sell one barrel of oil at $1 than two or three barrels at 25 or 35c. per bbl.

Jan 1, 1933

By R. C. Miranda

The purpose of this work is to present ?state of the art? mass balances closing strategies in ore treatment plants. It presents a brief history of difficulties and challenges ahead. The current methodology is based on usage of an expert system, which seizes and filters the plant data, analyzes situations of equipment stops and mostly instruments failures. It is still possible to internally create a strategy to check the data of an instrument failure. The system is coupled to software with a Lagrangian model of mass balance closure that receives the pre-treated data. Thus, the data goes through filtering and reconciling processes to generate a reliable mass balance of the ore treatment plant. This made possible to obtain a system that is able to tell the real productivity of a ore plant through reliable mass balances. Residence times on equipments are critical to the balance, thus, they require good logic to eliminate errors due to the characteristics of non-steady state. Among the next challenges is the inclusion of a ?soft sensor? as a replacement of an instrument required for mass balance closure.

Sep 1, 2012

By S. T. L. Harrison, M. A. Fagan-Endres, M. D. Odidi

This paper investigated the ability of eight common hydrodynamic models – tanks in series (TIS); three compartmental model configurations (Comp-1, Comp-2 and Comp-3); advection dispersion (AD); piston exchange (PE); piston exchange-diffusion variant (PE-D) and piston dispersion exchange (PDE) – to simulate residence time distribution (RTD) data generated from tracer tests conducted on a packed bed composed of different size fractions of malachite ore. The chosen materials were packed into 0.1 m internal diameter columns to a depth of 0.155 m and drip irrigated at 5.11 L/ m2.h. The four size fractions tested were: 1 – 2 mm, 2 – 2.8 mm, 4.75 – 5.6 mm and 13.6 – 16 mm. Step-up tracer tests were conducted using potassium chloride. The results showed that an increase in the particle size of the malachite ore had little effect on overall bed porosity but resulted in significantly lower values of liquid holdup. Two of the monoporosity models tested, TIS and Comp-2, were the most affected by the changes in bed size fraction due to their inherent inability to cope with high degrees of non-ideal flow present in the larger particle systems. The dual porosity models performed relatively better with the dominant trend being a reduction in dynamic to total liquid holdup as particle size increased. Of all the models tested, the PDE and TIS models were the best and worst performers respectively, with R2 values averaging at 0.997 and 0.679 across all experiments respectively. Though the Comp-1, Comp-3 and PE-D models also performed well, the addition of the dispersion coefficient to take the axial spread of fluid molecules into account added a layer of complexity that allowed the PDE model to perform relatively better than the other dual porosity models. Keywords: Heap leaching, packing material, hydrodynamics, malachite, PSD, modelling

Jan 1, 2020

By E. L. Chanturiya

During the mineral processing of pyrites sulphide ores of some deposits of Russia loss of gold with tailings and pyrite concentrates amounts up to 40%~90%. The problem of selective allocation of gold-bearing pyrite is crucial. There are 4 mineralogy-technological groups of pyrite determined in copper-zinc sulphide ores, based on the increase of contents of gold in pyrite. The gold associated with group 4 pyrite contents of 85% the total mass of gold found in the pyrite. The flotation behaviour of the enriched fractions of pyrite (98%), of the allocated from the ore of Gay deposit, were studied essentially in various conditions ?? and the charge of Butyl xanthogenate of potassium (ButX). Some products of selective pyrite flotation were investigated by methods of scanning electronic microscopy, energy-dispersive and X-ray spectral microanalyses, definition of specific resistance and thermoelectric moving force.

Jan 1, 2014

By B. H. Johnston, B. N. Doyle

Introduction In 1983-84 Kidd Creek Mines Ltd. in Timmins, Ontario, started up the second commercial zinc pressure leaching plant based on the Sherritt Gordon Mines Ltd. direct pressure leach process. The first plant using this process was that of Cominco Ltd. at Trail, B.C. (Parker, 1981; Martin and Jankola, 1985). The Kidd Creek plant was constructed to take advantage of the extra capacity that the existing purification, cell house, and casting sections had in comparison to the roasters and acid plant. In addition, pressure leaching offered flexibility in other areas such as treatment of low grade concentrates. The process design package and the detailed design of the autoclave system was carried out by Sherritt. The detailed design for the rest of the plant was done by Cambrian Engineering Ltd. under the direction of Kidd Creek. The construction and commissioning of the plant has been described earlier (Johnston, 1983). This paper describes, briefly, the application of the direct pressure leaching process for zinc concentrates and the integration of the pressure leaching plant into the main zinc plant at Timmins. It discusses some of the startup problems and changes made to the plant. The damage following a fire inside the autoclave is also described. The subsequent repair and recommissioning of the autoclave has enabled Kidd Creek to demonstrate the originally sought advantages of pressure leaching and to take advantage of their extra cell house and casting capacity to produce more zinc. Process principles The development of the direct pressure sulphuric acid leach of zinc sulphide concentrate at temperatures above the melting point of sulphur and at elevated oxygen pressure has been described in detail in a number of papers (Martin and Jankola, 1985; Johnston, 1983; Veltman and Bolton, 1980; Kawulka et al., 1975; Veltman et al., 1977). The most significant aspect of the process is that sulphidic sulphur is converted to elemental sulphur in reactions that can be simply described as follows. ZnS + H2SO4 + 1/2 O2 ZnSO4 + S° + H2O (1) FeS + H2SO4 + 1/2 O2 FeSO4 + S° + H2O (2) The rates of these reactions increase with temperature. However, at temperatures above the melting point of sulphur, 12°C, the presence of a surface active agent is necessary to prevent the occlusion of the sulphide particles by elemental sulphur and the consequent termination of the leach. The zinc that is dissolved according to reaction (1), after purification of the zinc sulphate solution, is recovered by electrowinning. The iron that is put into solution according to reaction (2) is further oxidized to the ferric state and subsequently, as the acidity decreases, precipitates as hematite or as complex basic sulphates. MINERALS AND METALLURGICAL PROCESSING Examples of this are shown below. 2FeSO4 + H2SO4 +1/2O2 - Fe2(SO4)3 + H2O (3) Fe2(SO4)3 + 6H2O - Fe2O3.3H2O + 3H2SO4 (4) 3Fe2(SO4)3 + 14H2O - 2(H3O)Fe3(SO4)2(OH)6 + 5H2SO4 (5) (hydronium jarosite) The conventional zinc process involves concentrate roasting to produce zinc oxide and sulphur dioxide. The zinc oxide is leached in spent electrolyte and the sulphur dioxide is converted to sulphuric acid. The pressure leaching process can, therefore, be used to replace conventional concentrate roasting, sulphuric acid manufacture, and atmospheric leaching with one unit operation. Integration of pressure leaching into the Kidd Creek flowsheet A block flowsheet of the Kidd Creek zinc plant, with the new pressure leach plant integrated, is shown in Fig. 1. The original plant, which was constructed in 1972, is based on standard electrolytic zinc plant technology. Concentrates are dead roasted to remove sulphur. Sulphur dioxide is treated to produce sulphuric acid. Calcine is leached in two stages using cell-house electrolyte. Iron is precipitated as jarosite and solutions are purified to remove copper, cobalt, nickel, and cadmium to provide feed for a partially mechanized cell house. Zinc is plated from solution, and the resulting cathode is melted, cast, and sold (Johnston, 1983). The integration of the pressure leaching plant into the main zinc plant is relatively simple. As shown in Fig. 1, a fraction of the zinc concentrate and spent electrolyte are fed to the pressure leach autoclave, while part of the calcine from the roaster is used as a neutralizing agent in the oxidation step along with. the jarosite leach solution. The main exit stream from the pressure leaching plant is the slurry discharged from the oxidation step, consisting of neutral zinc sulphate solution, unreacted calcine, and precipitated iron oxides. This slurry is transferred to the neutral leach step in the main zinc plant. The leach residue from the pressure leaching step, consisting of basic iron sulphate and elemental sulphur, is washed and impounded along with the jarosite residue produced in the main plant.

Jan 1, 1987

By Shengli Tao, Hongxu Li, Hao Bai, Yu Chen, Daqiang Cang

"China is the world's largest steel producer, in order to give environment load comprehensive analysis of steel and iron industry in china using LCA method, the life cycle inventory was compiled and assessment model based on Gabi software was also established. Environmental impact of two different routes ofBF-BOF and the EAF were analyzed respectively and intercompared. The results show that the modem EAF route is superior to the traditional BFBOF route on almost all the environmental impact indexes, which including acidification potential, eutrification potential, global warming potential, ozone depletion potential, etc. In the whole life cycle ofBF-BOF route in China, the transporting process ranks the biggest contribution part to the overall global warming potential, which can be explained by the fossil fuel burning of transporting vehicles during the long distance from Australia to China as the iron ore used are mainly imported from Australia. Apart from transporting process, Coking, blast furnace and iron mining processes could induce great environmental problems, while for the EAF route, the electricity consumption is considerable, which causing large amount ofC02 emission indirectly. Based on the analysis, several further countermeasures were proposed. Key words: Iron and steel industry, LCA, Gabi software, C02 emissionIntroductionCrude steel of china which reached 101.24 million tons in 1999 ranked the first column in the world since1999, So far has been to keep the world's largest steel output. At the year of2009, China crude steel output of 568 million tons, accounting for 46.6% of the global crude steel production, more than the total sum of crude steel production produced by 20 countries ranked behind. In 2011, China's crude steel production which is expected to be or close to 700 million tons, an increase of 12% than last year, will account for half of the global steel production.The steel industry, however, is intensive resources industry with huge consumptions of energy and water together with mineral resources. Energy consumption of the iron and steel industry has been about 10% of the total energy consumption since 1980. Coal dominants, power next and other energies share least in the energy consumption structure, for example coal accounts for 72.19%, power 23.52% and other total sums less than 5% in the steel energy consumption at year of 2002[2,3]. The consumption of coal discharges much emission of CO2, yet emissions of C02 in China steel industry, secondary only to the power and cement industry, ranked the third, and the coal dominant energy structure and its process have a close relationship. The aim of this research is to target steel production of typical blast furnace-converter (BFBOF) and electric furnace, using GABI software to evaluate and analyze resources and environment influence of LCA, directing at the existing problems in the development of China steel as well as finding the possible way to improve ability of reducing pollution and energy consumption in order to realize the sustainable development of the steel industry [ 4-7]."

Jan 1, 2012

By Walter W. Hyde

This paper describing the mining and preparation of sand and gravel for a number of special markets by the East Texas Gravel Co., Dallas, Tex., is one of a series being prepared on the subject by the United States Bureau of Mines. These articles are designed to disseminate technical information regarding the methods used. The cost tabulations represent operating expenditures only and not total production costs. It is recognized that publication of total production costs might in many instances cause embarrassment to individual producers as well as to the industry as a whole, but on the other hand, operating costs are essential to the technical discussion and study of the methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue.

Jan 1, 1931

By W. J. Mahoney

A good quality assurance program at a coal mine or power plant is accurate, timely and consistent. The quality analysis is accurate due to a complete sampling of the coal stream loaded into the unit train. The sample analysis is accurate because standardized testing procedures are applied. Once an analysis is completed, the results must be communicated to the electric utility in a timely manner. The electric utility needs the results to better manage the coal inventory at its power plants. A quality assurance program can also help a mine deliver a consistent product to a utility's power plants. The importance of accuracy, timeliness and consistency are based on major changes that are taking place in the electric utility industry.

Jan 1, 1994

By J. A. Maree

After the South Deep complex was purchased by Goldfields in 2006a re-feasibility study was done and the life of mine (LOM) was extended to 52 years. This also implied that the mine?s infrastructure would have to be enhanced. One of the changes was the proposal of five new main orepass systems to be excavated before the mine reaches full production in 2013. Excavations started to show signs of scaling, and in some cases, whole new excavations were lost. This particular area was exposed to very high stresses and the geology was prone to body delimination rendering the relevant areas unstable. This paper investigates the conditions at the location of one of the proposed orepass systems, and the best possible orientation was suggested to ensure that the orepass system would be stable and have a practical life. It was, however, found that the fourth leg of the orepass system would require further support to be classified as stable by the chief rock engineer and the section geologist of South Deep. Several support methods and orepass system linings would then be analysed and evaluated to give calculated recommendations on how to productively and practically support an orepass system. Keywords Main orepass system, stresses, body delamination, impact and abrasion, rock support, concrete lining.

Jan 1, 2011

By J Euston

In the 1990s round flotation tanks were introduced as a result of the lower fabrication costs for larger cells. It was soon observed that round tanks held a number of further advantages over the traditional rectangular cells, such as better hydrodynamics, lower costs and reduced footprint per unit volume.In the last twenty years flotation cell sizes have increased almost exponentially and designs of 250 to 300m3 are a well established standard with plans for full scale pilot installations of 500m3. The option to install these large cells gives flexibility in circuit arrangements and allows efficient and economic matching of flotation lines with modern mill designs. The benefits of scale up are well known with reduced numbers of cells required, lower power costs per unit volume, etc. These benefits will be briefly reviewed with specific reference to the installation of 300m3 to 350m3 flotation cells at the Copperton Concentrator of Kennecott Copper in Utah, USA.The sophisticated techniques required to model these ‘supercells’ have led to a critical review of the fundamentals of flotation science and engineering. In addition to outlining the advantages of large flotation cells, this paper will review the science which supports, and occasionally challenges, the ongoing trend to larger flotation cells.

Aug 8, 2011

By Mohammed Ali Shah, Martin Waller

The mining industry depends to a large extent on the availability of high performance equipment. For drilling this means a requirement for well engineered, reliable machines with mechanised handling and widespread utilisation of automatic control. Such machines enable performance optimisation of drilling operations and integration into a high productivity mining system. A review is presented of the current status of drilling technology as applied to the mining and minerals industry. This covers developments in: drill bit materials and design; drilling techniques; machine design; mechanisation; automation; and drilling control. It also covers the ways in which current and future mining methods and practices will influence the applications and demands placed on drilling activities. The probable impact of current research on the industry is discussed.

Jan 12, 1992

By Raja V. Ramani, Wilson Miola

The potential health effects of quartz-bearing airborne dust in mine and mill atmospheres point to the need for the quantification of quartz content in the source material for determining the source-sink relationships and for choosing applicable control measures. While a standard method exists from a regulatory point of view for the sampling of coal mine atmospheres for determining (i) respirable dust concentrations and (i) the amount of quartz in thesamples, there is no generally accepted standard method for quartz analysis in bulk samples of coal and host rocks. Generally, the bulk sample is reduced to a powder for producing quartz analysis samples. Extensive controls are necessary to ensure representativeness of the analysis samples when these are very minute fractions of the bulk samples. Since the amount of analysis sample is not limited, alternative methods for quartz analysis may also be tried. It is, however, necessary to adopt a procedure which will satisfy several statistical requirements to guarantee representativeness of the quartz analysis samples. In this paper, the important factors in the preparation of quartz analysis samples from the host rocks and bulk samples are discussed. The method developed to prepare the analysis samples is outlined. The results of application of the procedures are presented. The procedure developed for quartz analysis sample preparation is based on sound statistical foundations. The procedure has been validated for reproducibility and homogeneity.

Jan 1, 1991

By P. C. Thakur

The productivity in coal mines, measured in terns of the output per manshift depends largely on the efficiency and speed of men and materials transport between working faces and the surface. The mechanization of coal winning and material handling processes has led to a great rise in the mine productivity (1). Early applications of power in U. S. coal mines were mainly electrical. The excellent traction available with the DC motor and the ease of the distribution of the DC power have made trolley wire installations for haulage very popular. In shallow mines with very limited emissions of methane it did not constitute a major hazard but as mine depths increased and corresponding emissions of methane also increased fire and methane ignition hazards have become very serious. Conveyors have proved economic where intense mechanization of coal faces generates a large output of coal from a single face, but the fire and respirable dust hazard associated with them are no less serious. Recognizing these shortcomings, the Federal Coal Mine Health and Safety Act of 1969 laid down numerous provisions for the safe use of trolley-wire haulage and conveyors (2) which generally improve safety but in some cases complicate mining operations and have decreased productivity significantly since 1969. In course of time as coal mines become deeper and hence gassier and as the emphasis on safety increases it would be inconceivable to use trolley-wire haulage under ground as already witnessed in several other countries with deep coal mines. With rising capital investments and cost of the protection against fire and respirable dust, the use of conveyors may also have to be limited to special areas, e.g. main entries. Indeed, there are only two alternatives available, namely; (1) Degasify the coal seams prior to mining and use conventional electrical power, or (2) Develop alternate sources of power which would be safer and yet efficient and cheap.

Jan 1, 1975

By I T. Ross

Sampling drawpoints in block cave mines has been a contentious issue for many years. Doubts have been expressed as to the validity of the process used at most mines. This paper outlines the sampling practice commonly in use, discusses the resulting issues associated with reconciliation and drawpoint closure decisions. The paper also looks to the future and highlights issues for some block cave mining operations currently planned to have in the order of one thousand active drawpoints. It is likely that these operations will require a new approach to drawpoint sampling. There are several potential technologies currently available although some appear to be better suited than others to replace the current approaches. CITATION:Ross, I T, 2012. Sampling in block cave mines, in Proceedings Sampling 2012 , pp 81-86 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By J. E. Pahlman

As part of its effort to reduce the need for strategic minerals through conservation and to reduce the capital and energy requirements of mineral processing, the Bureau of Mines has investigated a method for preparing ferrochromium alloys containing less than 2 percent carbon. This method will conserve chromium and should reduce the capital and energy requirements for chromite reduction. Reduced products containing less than 2 wt-pct C and as low as 0.01 wt-pct C were obtained by reacting pellets of chromite and carbonaceous reductant mixtures at pressures of 0.1 to 1 torr and temperatures of 1,230° to 1,320° C. The extent of reduction increased with increased temperature and decreased pressure; however, operating conditions were limited due to the onset of significant chromium vaporization at higher temperatures and lower pressures. Foundry coke, anthracite, and carbon black were found to be supe¬rior to graphite as reductants. The reduction of chromite to metallics was found to proceed via the carbide intermediates (Fe,Cr)7C3 and (Fe,Cr)23C6, No evidence of carbide intermediates Fe3C or Cr3C2 was found. Buttons of ferrochrome alloys were made by melting a mixture of reduced products with CaO and Si02 at 1,700° C for 20 minutes in an induction furnace,

Jan 1, 1980

By H. Nejati

Experimentally, the Semi-Circular Bending Moment (SCB) fracture toughness test results of Basalt Specimens Under Illumination (BSUI) have shown reduction in fracture toughness and failure force as a result of micro-cracking. The fractographic investigation of BSUI confirms initiation and extension of micro-cracks. Determination of a relation between strength reduction (herein fracture toughness reduction) and density, location and orientation of thermo-mechanical induced cracks due to microwave radiation is critically important. Numerical modeling can bridge strength reduction and the density of thermal microcracks generated due to microwave radiation. Discrete Element Modeling (DEM) is a power tool for simulation of micro-crack initiation, coalescence into macroscopic fractures and failure mechanisms in brittle rock specimens under different stress regimes (herein combination of pure tensile stress due to SCB testing, and thermal stress due to microwave radiation). For this purpose, a DEM modeling of SCB testing of basalt using EDEM (i.e., a DEM based software). DEM models are calibrated according to results of experimental SCB testing as reported in previous papers. This paper first reviews some background data on SCB fracture toughness, and experimental results of fracture toughness of microwave treated SCBs. Then it proposes a new methodology for simulation and validation of rock samples exposed to microwave illumination with regard to experimental results, and discusses the correlation between fracture toughness of BSUIs and density of micro-cracks, which is attributed to applied microwave power and duration of illumination.

Aug 1, 2013

By Sunil K. Tripathy

Particle characteristics such as size, density, liberation and magnetic susceptibility play vital role in magnetic separation technique. To understand the performance of magnetic separation process for chromite beneficiation industry, particle characteristics need to be analysed. However, to date, this has been an expensive and time consuming task, thus only minimal amounts of this type of data are available in the literature. Several new methods are being developed, that will produce the required mineralogical and liberation data to provide processing information rapidly and inexpensively. Among these, QEMSCAN is a unique and advanced characterisation equipment used for liberation analysis for different ore whereas S.G. Franz Isodynamic Separator for determining the magnetic susceptibility. In Indian chromite deposits, the content of iron bearing minerals in the ore is typical which controls the Cr:Fe ratio in the product while treating in gravity based beneficiation plant. In the present investigation, detailed characterisation of two distinct chromite ore samples from Sukinda chromite deposit, India, was investigated which includes advanced mineral characterisation using QEMSCANand magnetic susceptibility measurement by using Frantz Isodynamic separator, etc.. Presence of haematite and gibbsite along with chromite mineral were identified as major gangue minerals in the high grade ore from XRD pattern whereas Goethite, Quartz, Haematite, Kaolinite, Ringwoodite identified in the low grade ore. The mass magnetic susceptibility of low grade ore is very high 5.2 cm3/g compared to 2.7 cm3/g for high grade ore, due to the presence of abundant quantity of iron bearing minerals. Subsequently, these two types of ore were subjected for magnetic separation for improving Cr:Fe ratio by using different magnetic separators viz. induced roll magnetic separator, wet high intensity magnetic separator, rare earth roll magnetic separator, rare earth drum magnetic separator. The results of magnetic separation studies indicated that, Cr: Fe ratio of the chromite ores can be improved to 3.99 and 1.97 from the feed assaying 3.09 and 1.29 respectively. Studies on rare earth roll magnetic separator indicated that both the ores were upgraded to a maximum Cr:Fe ratio level at optimised condition. Keywords: characterization, QEMSCAN, magnetic separation, rare earth roll magnetic separator, industrial mineral, chromite

Sep 1, 2012

By Peter Bauer, Klaus Gamweger

"Gas purging systems are well established in nonferrous metallurgy at multiple steps during metal production, including melting, converting, alloying, and metal cleaning. Since the kinetics of all of these stages are positively influenced by using gas purging systems the overall process benefits are substantial. In the aluminum industry, inert or reaction gases are blown into the melt using porous plugs to achieve improved metal grades, higher productivity, and more efficient energy utilization. To enable the most effective application of the process gases a complete package, termed AL KIN, was developed by RHI that includes porous plugs, refractory expertise, gas supply technology, and gas control equipment. This paper discusses the technological and economic advantages of this system and the specific benefits of fuel reduction, production time savings, decreased process gas consumption, and improved refractory service life and maintenance are illustrated using an aluminum slug plant in Austria.IntroductionIn addition to high quality production, increasing productivity is the main goal in many aluminum cast houses to maintain or even strengthen their market position. The Neuman Aluminium Group, based in Austria, North America, and based in Austria, North America, and China, is the largest slugproducer for tubes, cans, and automotive parts worldwide. Recently, a comprehensive improvement program was initiated at the Neuman Aluminium Austria slug plant in Marktl - the main factory and technological centre of the group. The principal goal of the optimization project was to increase the productivity of the strip-casting production. The investment included a gas purging system, ingot preheating equipment, a new insulated launder system, and optimized melting cycles. However, the introduction of the gas purging system was pivotal to the project and has accounted for approximately 50% of the benefits achieved. This paper describes the AL KIN gas purging technology and details the process benefits resulting from the improvements at Neuman Aluminium Austria."

Jan 1, 2009

By A. B. Hooker

Investigations at the Pittsburgh Experiment Station have shown that the satisfactory operation of a flame safety lamp depends not only upon proper design and assembly of the lamp but upon the kind of fuel used, and that much of the trouble experienced with permissible flame safety lamps at mines is due to the common use of motor gasolines, none of which is suitable in the present types of permissible flame safety lamps. This report gives the results of a limited study to determine what satisfactory fuels are available, the specification limits of such fuels, and to suggest modifications of assembly and care of the lamps to improve performance with any satisfactory fuel.

Jan 1, 1938