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By G. W. Govier

Measurements of the settling rates and the rheological behaviour of heavy media formed of fine suspensions in water of each of magnetite, ferrosilicon, and galena have been made. For media ranging from 1.6 to 2.8 specific gravity the settling measurements gave initial settling rates of from 0.5 to 0.01 ?cm. 'Per minute for magnetite; from 4.0 to 0.8 cm. per minute for galena; and from 35 to 1.6 cm. 'Per minute for ferrosilicon. These measurements indicate the ?relative stability of the suspensions and should be helpful in establishing the useful specific gravity range for each medium. Measurements of the consistency of the media were made with a Fann Model 35 rotational viscometer. Aibnormal or non-Newtonian behaviour was observed in the case of each media, the apparent viscosity being dependent upon the rate of shear or the intensity of motion. Measurements were made over the rate of shear range of 10? to 1,000 reciprocal seconds. The apparent viscosities of the magnetite media ranged from 450 down to 4?0 centipoise at 2.30 specific gravity, and from 2,450 down to 700 centipoise at 2.80 specific gravity. In the case of the galena media, the variation was from 40, through a minimum of 6, to 10 centipoise at 2.20 specific gravity, and from 950, through a minimum of 180, to 450 centipoise at 3.6 specific gravity. The ferrosilicon suspensions exhibited apparent viscosities ranging from 42, through a minimum of 5.6, to 9 centipoise at 1.9 specific gravity, and from 160, though a minimum of 35, to 85 centipoise at 2.8 specific gravity. The dependency of apparent viscosity or consistency upon intensity of motion is considered to be of particular significance in applications of heavy media where the medium is in rapid motion.

Jan 1, 1957

The Santa Rita mine is located in north eastern part of Bahia in Brazil and is owned and operated by Mirabela Mineração do Brasil Ltda. Typical SABC circuit was designed as the preferred option for the 4.0 mtpa (500tph) to produce a P80 of 125um for flotation. Although the SAG was originally designed to operate with conventional radial pulp lifters, later it was fitted with Outotec?s Turbo Pulp Lifters ? TPL (Latchireddi, 2005). The milling circuit commenced commissioning on the 24th of October 2009 and the milling circuit achieved the nameplate capacity within days. with small and relatively simple measures to rectify. Since commissioning, the SAG mill has been working in fully autogenous grinding (FAG) mode with no balls (in contrast to the estimated 10% ball charge) and has been consistently treated up to 650tph. This paper examines the comminution design process, the operating philosophies, start-up experiences, post commissioning optimization and future development works. An evaluation of mill performance relative to the design criteria for the project life to date is also included.

Jan 1, 2012

By Longjiang Li, Song Mao, Zhengyang Qiao, Qin Zhang, Guizhou University, Ling Wang

"After a study on the advantages and disadvantages of flotation column, according to the limitation of ordinary flotation column only is used for a flotation of microgranular minerals, the paper designed a new kind of layered convection coarse particle flotation column.Using a bauxite to test the rationality of the flotation column.The test results show that the new layered convection coarse particle flotation column is feasible.It has certain advantages about coarse particles flotation.INTRODUCTIONFlotation column has many advantages, for example,a simple structure, high efficiency and energy saving, the obvious advantage of fine particles flotation , the index superior and so on. The advantages gradually getting people's recognition. Research of flotation column has been a breakthrough, however, due to it only is used for the flotation of microgranular minerals, and the microgranular mineral particles will lead to a series of problems, and makes the processing cost is increased. Due to increase grinding fineness can save the grinding time and reduce the cost of grinding, also can avoid the disadvantage of fairly granular mineral particles cause a deterioration in the flotation. So it is necessary to research a kind of coarse particle flotation column.After a research on the advantages and disadvantages of flotation column, the authors designed and manufactured a new layered convection coarse particle flotation column, the flotation column both in theory and operation is better than flotation machine.DESIGN OF THE LAYERED CONVECTION COARSE PARTICLE FLOTATION COLUMNAdvantages and Disadvantages of the Traditional Flotation ColumnIn the field of mineral processing, as the increasing proportion of ore that has low grade, fine dissemination size, complex mineral composition characteristics. The limitations of traditional flotation machine is increasing[1],for instance, the high energy consumption, severe wear, inconvenient configuration , large amount of maintenance and so on. Compared with flotation machine, the flotation column with high separation efficiency, low investment and production cost, covers a less area low installation cost, less reagent dosage, more suitable for separation of fine particles and can automatically control, etc[2]. At present, the ore is facing the world energy crisis situation, and becoming increasingly difficult to flotation. So it is important to invent a coarse particle flotation column."

Jan 1, 2016

By Martin Bergeron

Producteur d?or de taille intermédiaire Mines Aurizon Ltée Bureau-chef àVancouverMine et projets localisés au Québec2

May 1, 2011

By Hyung Sup Choi

The preparation of high-purity zirconyl compounds was studied in order to develop an economical process for obtaining pure zirconium via the caustic fritting of zircon sand. The direct dissolution of caustic frits with concentrated hydrochloric or nitric acid at 80c. followed by the addition of a small amount of acidified gelatin, gave high-purity zirconyl chloride or nitrate. The addition of a small amount of gelatin caused a mutual flocculation between colloidal silica and gelatin. The precipitation of this silica floc markedly lowered the content of silica in the product. The silica content of the compounds (or solution) so produced, generally less than 100 ppm., was sufficiently low for tributyl phosphate extraction for nitrate solutions. It was found that the degree of purification de-pends not only on the procedures employed but also on the nature of the frit itself. Silica was more effectively eliminated from the fritted product produced at higher temperatures, and less silica was present in the com-pound prepared from the frit produced in a shorter heating time. In order to ascertain the nature of the

Jan 1, 1965

By R. S. Jones

"Fording Coal Ltd. is now in its fifth year of a 15-year contract to supply 3 million long tons of clean coal per annum to its Japanese steel-making customers. The mine employs both conventional truck-shovel and unconventional ""walking"" dragline coal mining techniques in multiple-seam pits. This paper describes the present and future application of the 60-cu.-yd dragline and truck-shovel pre-stripping fleet in 1•ecovering 5- to 40-footthick coal seams in mountainous terrain. Deep blastholes, coal flow demands, spring ""run-off"", seam and inter-seam thrust faulting, limited seam outcrop data and regional faulting are a few of the problems encountered in this application. The author discusses these problems and their solutions as applied at Fording Coal Ltd."

Jan 1, 1976

By Habib Zughbi, Paul Zulli

"A key step towards sustainability in iron and steelmaking is to optimise the use of raw materials and energy consumption, and consequently minimise CO2 emissions. Models based on a Process Integration (PI) approach play a key role in evaluating various scenarios and the impact of introducing changes in raw materials and operational conditions on the overall energy consumption and CO2 emissions. BlueScope uses a PI based comprehensive model for its Port Kembla Steelworks (PKSW), called the Integrated Steelworks Energy and Emissions Model (ISEEM). ISEEM is tightly coupled to the configuration of PKSW. It is based on mass and energy balances as well as thermodynamic relationships. ISEEM is a steady-state model and is used to predict overall and detailed unit-by-unit energy consumptions and CO2 emissions. It is also used for plant-based scenario modelling. This paper investigates the impact of major changes to PKSW configuration, including the shutting down of a blast furnace and cokemaking battery, on the energy consumption and CO2 emissions of the plant. It discusses some of the issues involved in updating the model and some identified opportunities."

Jan 1, 2015

By Shiqiang (Rob) Hui, Jiaren (Jimmy) Jiang, Rees Llewellyn, Yongsong Xie

Wear has been estimated to cost the Canadian mining/mineral processing industry over $15 billion per year mainly for repair/replacement of worn parts in 2013. The associated production loss is difficult to quantify but add considerably to the problem. The Canadian oil sands sector which has to deal with extremely abrasive and erosive solids, has traditionally incurred extremely severe and often unique attack. Demonstrable progress in mitigating the wear problems has been achieved through materials development, more informed materials selections, and better component and operation condition designs. An integral contributor to these advances is a long-term collaborative research partnership between NRC and the mining/supply industry. In this paper, this continuing collaboration will be described. A main focus is to identify degradation mechanisms occurring in the most severe and important service applications and to correlate these findings with laboratory test data. Relevant abrasion and erosion (often combined with corrosion) properties have been established and correlated with composition and microstructures for all classes of resistant materials ranging from relatively soft elastomers to ultra-hard ceramics. A comprehensive wear properties database has been compiled. This capability has been instrumental in facilitating the development of improved materials, optimizing materials fitness/selection for service, wear failure analysis, and quality assurance.

Jan 1, 2015

"Projections of demand for Alberta coal indicate a quadrupling of current production rates to some 70 million tonnes/year by the end of the century. About half of this output-comprised of subbituminous coal-will be required within the province, primarily for generation of electric energy. The remainder-roughly 70 per cent high-volatile bituminous (hvb) steam coal and 30 per cent medium- or low-volatile bituminous (mvb/lvb) metallurgical coal-will be exported, principally to Pacific Rim and Western European countries. Direct employment in mining and coal processing is projected to increase from the present ca. 3000 to at least 12,000 persons.This paper presents separate forecasts for subbituminous, hvb and mvb/lvb coal production in the period 1982-2000; notes a number of possible developments that could substantially modify these forecasts; and briefly discusses attendant infrastructure requirements. Attention is drawn to potential shortages of qualified manpower and to threatening inadequacies of transportation facilities.IntroductionDespite the dislocations triggered by the 1973 'oil crisis', energy budgets of Western industrial countries are mostly still in the very early stages of the anticipated transition to greater reliance on coal. Shift s to coal are still more often only talked about than being implemented; and the public policies which are essential for timely development of facilities for producing, transporting and using coal are in many instances not yet even broadly formulated, let alone enunciated.In these circumstances, long-range projections of coal demand and supply-even if restricted to internal requirements- are subject to greater uncertainties than usually afflict such forecasts.On the demand side of the equation, these uncertainties arise ultimately from linkages between a need for coal and the availability and pricing of OPEC oil. The current surplus of oil on world markets, which has recently forced substantial reductions of posted prices, is undoubtedly a transient phenomenon that is unlikely to have any long-term impact."

Jan 1, 1982

By D. Fodor

In Romania, there are significant lignite and brown coal reserves hosted by different regions of the country. The most important lignite bearing zone of the country situated in the North ? West part of Oltenia region and which covers a surface area of 2,500 km2 and host a total reserve of 3.0 billion tons of lignite, of which more than 95% can be exploited by open cast method. The paper deals with the existing geological and mining conditions of the zone , the distribution by mining basins and exploitation perimeters, the open cast working technologies and the economic outcomes obtained throughout the time. Years ago, for the improvement of the economic situation as a whole and in each unit, a large production reorganization, technology update and modernization process was started up. There are described the rehabilitation measures of the technological lines and modernization of the equipments of the production flow-sheet, measures developed at present, too and which will still continue in future. There are mentioned the equipments considered, the components under modernization and the economic outcomes obtained so far. At the end of the paper there are presented the future actions for the equipment modernization and perspectives of the lignite deposit exploitation to meet the national economy requirements of solid fuels.

Aug 1, 2013

By Baisheng Nie, Longlong Yang, Tao Yang, Wenjie Jia

"Gas adsorption in coal is an exothermic and physical process. Temperature might change during the dynamical process. In order to get the temperature variation of gas adsorption process, the experiment system which can test the temperature variation and analyze the thermal effect was established. Gas adsorption experiments under different conditions were done by using the test system. The results show that temperature increases during the adsorption process. It is an exothermic reaction process. Also, the temperature variation and the variation gradient increase with the increasing of equilibrium pressure. The temperature variation value is smaller if the experiment temperature is higher. The paper will provide basic experimental data for explaining gas adsorption mechanism better.INTRODUCTIONChina is the largest coal producer in the world while it also has the most serious coal mine disasters. According to the statistics, there are nearly a thousand coal mines in China including more than 110 the key state-owned mines risking to happen coal and gas outburst. Hundreds of coal and gas outburst occur each year which often causes serious casualties and economic losses (State Administration of Work Safety, 2007). With the continuing exploitation of the coal resources, the depth of the Chinese coal mines increases about 100 meters every year which causes the situation of gas accident becoming more and more serious (Xie et al., 2006).At present, the real mechanism of gas adsorption, desorption and the diffusion process in coal and the influence factor of it are not so clear. And because of the limit of prediction method and the technological level caused gas accident prevention theory and technology not so valid."

Jan 1, 2015

By A. -M. Lafront

The corrosion resistance of die-cast and freely-solidified and electromagnetically-stirred thixocast AZ91D alloy has been studied using electrochemical noise technique in a 0.05M NaCI solution at pH 6.1 and 25°C. Specimens polished at different depths were immersed for a period of 75 min in order to assess the influence of the microstructure on corrosion kinetics and morphology. At depths between 10 and 50 µm (skin), all specimens showed general non-uniform corrosion with the lowest corrosion resistance. Between 100 and 200 µmn (interior skin), the observed corrosion was accompanied by superficial undefined pits due to metastable pitting. The corrosion form for 100-200 µm gave the best corrosion resistance. Stable pitting corrosion was observed beyond 400 µm deep on the bulk specimens. The skin of all thixocast specimens prepared billets showed a more corroded surface than that of die-cast. The interior skin as well as the bulk specimens showed better performance than that of the die-cast specimens.

Jan 1, 2007

By S. P. Chong, N. C. Shih, G. A. Turner

Fine powders, with the bulk of the particle diameters Jess than 10 microns, were aerated so that each particle was, on the average, separated from its neighbours by 1.3 to 2 mean diameters. In this state, measurements were made of the viscosity and settling rate of the powder, and the interfacial tension between it and a moist pellet. From the viscosity measurements, qualitative analogies are drawn between the behaviour of the aerated powder and that of a dense gas near its critical point.

Jan 1, 1970

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 J. A. Drozdiak

In this paper we examine, through pilot-scale testing, the possibility of operating a circuit comprised of two stages of HPGR comminution, followed by grinding through a horizontal stirred mill. In order to assess whether the novel circuit design could achieve the reduced energy requirements indicated in the literature, two more-established circuits, a cone crusher / ball mill and an HPGR / ball mill, were examined using a combination of testing and flowsheet simulation. The results showed that, based solely on the specific energy requirements for comminution, the HPGR / stirred mill circuit achieved a reduction of 9.2% and 16.7% over the HPGR / ball mill and cone crusher / ball mill circuits, respectively.

Jan 1, 2012

By D. Tao

The adverse effects of clay particles on coal and mineral processing processes such as gravity separation, flotation, filtration, and thickening are well known in the mining industry. In particular, the presence of ultra-fine clay particles deteriorates froth flotation performance, which has been attributed largely to slime coatings that inhibit bubble attachment and to adsorption of the frother and/or collector by the clay particles. The present study was conducted to evaluate the performance of clay binding agents developed by Georgia-Pacific Resins, Inc. in enhancing coal and mineral flotation performance. Mechanical and column flotation tests were carried out using coal and potash samples. Process parameters investigated include slurry solids percentage, impeller rotation speed, binder dosage, collector dosage, etc. Flotation results show that use of GP reagents significantly enhanced flotation efficiency under different conditions. The required binder dosage and conditioning time was about 1 lb/t and 0.5-1 min, respectively. More significant improvements in process performance were observed at higher solids percentage and higher impeller rotation speed.

Jan 1, 2006

By AN. Kumar

Two fabrication stages in the manufacture of pipelines are identified as causing significant deterioration of the steel plates, namely cold bending and welding. The objectives of this work include quantitative assessment of the degradation of the quality of the steel plate by the loss of fracture toughness, and an estimation of the safe working pressure. The study was conducted on three API grade steels: X42, X46 and X60. After cold bending by the UO technique, various welding technique were employed for joining of the bend plates along the pipe length. A crack-tip opening displacement parameter (CTOD) was used at the onset of initiation and at the first load maxima as the criterion for assessing the toughness degradation under various fabrication stages and regime (such as WZ, HAZ and parent body). In addition, strength, hardness and impact energy values were determined to check the degree of degradation. Microstructural and microfractographic investigation of the fractured samples were also carried out in the scanning electron microscope (SEM). X60 grade steel plate suffers from CTOD toughness loss by around 38 and 55% after welding and cold bending, respectively, for the conditions studied. A combined effect of the two stages results in a loss in toughness by around 70% for the same steel. In X42 grade, the loss in impact energy ranges from 78 to 35 J due to electrical-resistance welding study (ERW). Crack resistance curves are also obtained for the steels to study the crack growth resistance behaviour and to supplement the information on crack initiation behaviour. The orientation of the pearlite banding, as observed on the fracture plane with respect to notch front and applied loading direction appears to have a strong influence on the microvoid-coalescence mechanism of fracture as well as the toughness values. An integrated analysis of the performance of pipelines, considering all these key factors, is discussed.

Jan 1, 2005

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 Rakesh Kumar, Rajabrahma K., A. K. Verma, V. Mukesh

"In this study, laboratory investigation as well as numerical investigation is carried out to ascertain the transition from one mode to another for Semi-circular bend setup. Laboratory investigation is carried by varying the span length (s/2R); crack length (a/R); notch angle (a); and notch thickness (t). The specimen consists of cement, sand and water mixture in a ratio of 1:1:0.5 by weight and are prepared as per the ISRM standards (2014). Tests are conducted by a servo controlled universal testing machine at a strain rate of 0.2 mm/ min. The results are collected in terms of failure load, crack mouth opening displacement (CMOD) and images of crack initiation and propagation.Image analysis of laboratory tested samples shows that crack initiates at the notch tip when the notch inclination angle is 0°. As the notch angle increases (i.e. 30° and 60°) the fracture begins to initiate behind the notch tip. The direction of crack propagation in front and back side of the sample is same for notch inclination angle is 0° whereas it differs more and more as crack inclination increases. The transition represents the change in mode of failure from mode I (0°), mode II (30°) and mixed mode I/II fracture (60°).Finite element method used to find the transition based on MTS failure criterion. The inclination of notch is varied like 40, 42, 44, 45, and 50 deg and FEM analysis shows that the transition from mode-I to Mode-II take place at 49 deg. The same procedure can be extended to find the transition from mode-II to mode-III."

Jan 1, 2015

By P. Karimi, G. Mollataheri, A. Amini, H. Abdollahi, A. Mirzaeian

"Chah-Palang tungsten deposit is one of the two tungsten indexes in Iran. Based on ore characterization techniques (including optical mineralogy and XRD analysis), quartz, chlorite, atacamite, azurite, malachite, ferberite, illite, goethite and calcite were distinguished as major minerals. The representative sample was analyzed qualitatively by using X-ray fluorescence and chemical assay. Results showed that grade of tungsten oxide and copper were 1.76 and 7%, respectively. Also precious metals such as gold with grade of 1 ppm was reported in the sample. By using the mineralogical studies on the prepared sample, the liberation degree of tungsten minerals in –0.6 mm size fraction was obtained 80%. Several tabling tests were carried out on the original sample which at the optimum conditions and as a result, the grade and recovery of tungsten in concentrate reached to proximately 23 and 59%, respectively. To increase the grade of tungsten in the final concentrate, acidic leaching were performed on the tabling concentrate and its appropriate results indicated that the grade of tungsten increased to 27%. Also more than 90% of copper was extracted as a byproduct in the fallowed process.INTRODUCTIONTungsten, a unique hard, heavy heat-resistant metal, is distributed erratically in economic concentrations throughout most continents, occurring mostly as small irregular deposits that are not readily adaptable to large-scale, low-cost mining methods. The diverse physical characteristics and mineral composition of tungsten ores also present problems in beneficiation, requiring complex hydro- and pyrometallurgical treatment to yield high-purity concentrates suitable for the production of ferro alloys, carbides and super alloys in the steel industry (Hausen, 1989; Kholmogorov & Kononova, 2005). Tungsten is most frequently used as tungsten monocarbide, which has hardness close to diamond, in cemented carbides. The most well-known use of tungsten is in lighting filaments, and other important applications include improving steel properties and use in tungsten alloys, electronics, and chemical products (Hausen, 1989; Kholmogorov & Kononova, 2005)."

Jan 1, 2016