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Michael Hitch - One of the best experts on this subject based on the ideXlab platform.
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structural and chemical changes in mine waste mechanically activated in various Milling environments
Powder Technology, 2017Co-Authors: Jia-jie Li, Michael HitchAbstract:Abstract This paper evaluates the mechanical activation of mine waste (e.g. partially serpentinized olivine) using different Milling machines, with a special focus on changes in microstructure and chemical transformation. The mechanical activation experiments were carried out using lab-scale high-energy planetary and vibratory Mills, as well as a pilot-scale Stirred Mill, and laser diffraction, nitrogen adsorption, X-ray diffraction, and infrared spectroscopy were employed to identify mechanically-induced changes in the mine waste. Direct aqueous carbonation was used to identify the best type of mechanical activation for carbon storage in the mine waste. The experimental results demonstrate that agglomeration of the particles takes place during extended Milling in dry conditions, and that there is an effective mechanical activation limit for crystallite size reduction during dry grinding; the higher the Milling intensity, the smaller the forsterite's crystallite size will be at the mechanical activation limit. Additionally, Stirred Milling in wet conditions produces the largest specific surface area, and vibratory Milling in dry conditions generates the most disordered materials. The serpentine content was slightly dehydrated during dry Milling and was not activated at all during wet Milling. The Stirred Mill proved to be the most efficient form of mechanical activation vis-a-vis the direct aqueous carbonation process, followed by the planetary Mill and the vibratory Mill, respectively.
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Ultra-fine grinding and mechanical activation of mine waste rock using a high-speed Stirred Mill for mineral carbonation
International Journal of Minerals Metallurgy and Materials, 2015Co-Authors: Jia-jie Li, Michael HitchAbstract:CO_2 sequestration by mineral carbonation can permanently store CO_2 and mitigate climate change. However, the cost and reaction rate of mineral carbonation must be balanced to be viable for industrial applications. In this study, it was attempted to reduce the carbonation costs by using mine waste rock as a feed stock and to enhance the reaction rate using wet mechanical activation as a pre-treatment method. Slurry rheological properties, particle size distribution, specific surface area, crystallinity, and CO_2 sequestration reaction efficiency of the initial and mechanically activated mine waste rock and olivine were characterized. The results show that serpentine acts as a catalyst, increasing the slurry yield stress, assisting new surface formation, and hindering the size reduction and structure amorphization. Mechanically activated mine waste rock exhibits a higher carbonation conversion than olivine with equal specific Milling energy input. The use of a high-speed Stirred Mill may render the mineral carbonation suitable for mining industrial practice.
Oktay Celep - One of the best experts on this subject based on the ideXlab platform.
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optimization of some parameters of Stirred Mill for ultra fine grinding of refractory au ag ores
Powder Technology, 2011Co-Authors: Oktay Celep, N Asla, Ibrahim Alp, Gokha TasdemiAbstract:Abstract In this study, optimization of some parameters of Stirred Mill on ultra-fine grinding of refractory Au/Ag ores was performed. A three-level Box–Behnken design combining a response surface methodology (RSM) with quadratic programming (QP) was employed for modelling and optimization of some operating parameters in ultra-fine grinding. Grinding tests were carried out in a laboratory scale pin-type vertical Stirred Mill. The relationship between the response, i.e. d80 size, and four grinding parameters, i.e. ball diameter, grinding time, ball charge ratio and stirrer revolution was presented as empirical model equations. Analysis of variance showed a high coefficient of determination value (R2 = 0.9698), thus ensuring a satisfactory of the second-order regression model with the experimental data. The model equations were then optimized using the quadratic programming method to minimize for d80 size within the experimental range studied. The optimum conditions were found to be 1.61 mm for ball diameter, 11.50 min for grinding time, 80% for ball charge ratio and 745 rpm for stirrer revolution for this grinding process. In order to verify the improvement of grinding performance using the optimal level of control factors three verification experiments were conducted, and the results for d80 was 3.37 μm, which were smaller than those obtained in the initial tests.
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Optimization of some parameters of Stirred Mill for ultra-fine grinding of refractory
2011Co-Authors: Oktay Celep, N. AslanAbstract:article i nfo In this study, optimization of some parameters of Stirred Mill on ultra-fine grinding of refractory Au/Ag ores was performed.A three-levelBox-Behnkendesigncombining a response surface methodology(RSM)withquadratic programming (QP) was employed for modelling and optimization of some operating parameters in ultra-fine grinding. Grinding tests were carried out in a laboratory scale pin-type vertical Stirred Mill. The relationship betweentheresponse,i.e.d80size,andfourgrindingparameters,i.e.balldiameter,grindingtime,ballchargeratio andstirrerrevolutionwaspresentedasempiricalmodelequations.Analysisofvarianceshowedahighcoefficient of determination value (R 2 =0.9698),thusensuringa satisfactoryofthe second-orderregression modelwith the experimental data. The model equations were then optimized using the quadratic programming method to minimize for d80 size within the experimental range studied. The optimum conditions were found to be 1.61 mm for ball diameter, 11.50 min for grinding time, 80% for ball chargeratio and 745 rpm for stirrer revolution for thisgrinding process. In order to verify the improvement of grinding performance using the optimal level of control factors three verification experiments were conducted, and the results for d80 was 3.37 μm, which were smaller than those obtained in the initial tests.
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İNCE ÖĞÜTME TEKNOLOJİSİNDE KARIŞTIRMALI ORTAM DEĞİRMENLERİ VE CEVHER HAZIRLAMADAKİ UYGULAMALARI Stirred MEDIA MillS IN ULTRAFINE GRINDING TECHNOLOGY AND THE APPLICATIONS IN ORE DRESSING
2008Co-Authors: Oktay CelepAbstract:Stirred media Mills are widely used for ultra fine grinding of minerals and other materials to particles size below a few micrometers in different industrial fields such as ore dressing, plastic, ceramics, paint, food and cosmetic. These Mills can be classified into a number of different subcategories predominantly defined by the speed, geometry, and orientation of the media agitator or stirrer. Two basic types of Stirred Mills are available, the vertical Stirred Mill and the horizontal Stirred Mill. The specific energy consumption for grinding is less than that of tumbling Mills due to the high media volumetric loading in Stirred Mills. In Stirred Mills, mineral type, and specific energy input, the bead size and load volume play an important role in the comminution process and influence the stress intensity and stress number taking place in Mill. In this paper, the parameters effecting grinding and general properties of Stirred Mills are discussed and applications in ore dressing as well as other industrial fields are reviewed.
Jia-jie Li - One of the best experts on this subject based on the ideXlab platform.
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structural and chemical changes in mine waste mechanically activated in various Milling environments
Powder Technology, 2017Co-Authors: Jia-jie Li, Michael HitchAbstract:Abstract This paper evaluates the mechanical activation of mine waste (e.g. partially serpentinized olivine) using different Milling machines, with a special focus on changes in microstructure and chemical transformation. The mechanical activation experiments were carried out using lab-scale high-energy planetary and vibratory Mills, as well as a pilot-scale Stirred Mill, and laser diffraction, nitrogen adsorption, X-ray diffraction, and infrared spectroscopy were employed to identify mechanically-induced changes in the mine waste. Direct aqueous carbonation was used to identify the best type of mechanical activation for carbon storage in the mine waste. The experimental results demonstrate that agglomeration of the particles takes place during extended Milling in dry conditions, and that there is an effective mechanical activation limit for crystallite size reduction during dry grinding; the higher the Milling intensity, the smaller the forsterite's crystallite size will be at the mechanical activation limit. Additionally, Stirred Milling in wet conditions produces the largest specific surface area, and vibratory Milling in dry conditions generates the most disordered materials. The serpentine content was slightly dehydrated during dry Milling and was not activated at all during wet Milling. The Stirred Mill proved to be the most efficient form of mechanical activation vis-a-vis the direct aqueous carbonation process, followed by the planetary Mill and the vibratory Mill, respectively.
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Ultra-fine grinding and mechanical activation of mine waste rock using a high-speed Stirred Mill for mineral carbonation
International Journal of Minerals Metallurgy and Materials, 2015Co-Authors: Jia-jie Li, Michael HitchAbstract:CO_2 sequestration by mineral carbonation can permanently store CO_2 and mitigate climate change. However, the cost and reaction rate of mineral carbonation must be balanced to be viable for industrial applications. In this study, it was attempted to reduce the carbonation costs by using mine waste rock as a feed stock and to enhance the reaction rate using wet mechanical activation as a pre-treatment method. Slurry rheological properties, particle size distribution, specific surface area, crystallinity, and CO_2 sequestration reaction efficiency of the initial and mechanically activated mine waste rock and olivine were characterized. The results show that serpentine acts as a catalyst, increasing the slurry yield stress, assisting new surface formation, and hindering the size reduction and structure amorphization. Mechanically activated mine waste rock exhibits a higher carbonation conversion than olivine with equal specific Milling energy input. The use of a high-speed Stirred Mill may render the mineral carbonation suitable for mining industrial practice.
Peter Radziszewski - One of the best experts on this subject based on the ideXlab platform.
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Understanding the effect of pressure profile on Stirred Mill impeller wear
Minerals Engineering, 2017Co-Authors: Peter Radziszewski, Adam MooreAbstract:Abstract Since about the late-1970s, Stirred Mills have entered into use in the mineral processing industry. Much work has focused on model developed for power, grinding and performance prediction. However, little effort is cited in the literature related to wear and particularly impeller wear. In this paper, the focus will be on examining how two pressure profile models might affect Stirred Mill impeller wear profiles specifically in the gravity induced Stirred Mill case. The investigation will start with a re-visit of a mechanistic impeller wear model for Stirred Mills which includes some indications on how impeller wear affects Mill power. Subsequently a review of a few pressure profile models analysis will lead to exploring the effect of the pressure profile on impeller wear. The paper will close with a discussion on how the model could be used to illustrate the effect of wear on any impellor design.
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Generalizing a shear–volume power model for Stirred Mill power prediction
Minerals Engineering, 2015Co-Authors: Sudarshan Martins, Peter RadziszewskiAbstract:Abstract A Stirred Milling model, based on the concept of shear–volume power, was developed and applied to geometries typically found in mineral processing systems. Generalising this model permits its use to model more complex Mill geometries, such as those describing a tapered disk Mill and the CoBal Mill. Due to the additive property of the shear–volume power, the calculation of the power of complex Mills is possible through geometric decomposition. This approach is supported by the calculation of the shear–volume power of a number of simple geometries commonly found in Mills, and is used in the calculation of the shear–volume power of a tapered disk Mill and the CoBal Mill. Finally, by incorporating a breakage model, an equation that offers some usefulness in the design, operation and optimization of Stirred Mills is presented.
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generalizing a shear volume power model for Stirred Mill power prediction
Minerals Engineering, 2015Co-Authors: Sudarshan Martins, Peter RadziszewskiAbstract:Abstract A Stirred Milling model, based on the concept of shear–volume power, was developed and applied to geometries typically found in mineral processing systems. Generalising this model permits its use to model more complex Mill geometries, such as those describing a tapered disk Mill and the CoBal Mill. Due to the additive property of the shear–volume power, the calculation of the power of complex Mills is possible through geometric decomposition. This approach is supported by the calculation of the shear–volume power of a number of simple geometries commonly found in Mills, and is used in the calculation of the shear–volume power of a tapered disk Mill and the CoBal Mill. Finally, by incorporating a breakage model, an equation that offers some usefulness in the design, operation and optimization of Stirred Mills is presented.
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Shear based Stirred Mill power model – An adimensional analysis
Minerals Engineering, 2015Co-Authors: Peter RadziszewskiAbstract:Abstract Stirred Mill power has been modelled empirically, adimensionally and computational intensively through the use of the discrete element method and computational fluid dynamics. To this range of power modelling efforts, one more is added through the development of a shear based power for Stirred Milling. The resulting shear based power model incorporates dimensions of stirrer and chamber geometry as well as operating conditions. In this paper, adimensional analysis, namely Newton and Reynolds numbers, will be used in this paper to explore how this shear based model behaves over a few data sets. A discussion is included on how this model could be improved and used for characterising industrial applications.
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shear based Stirred Mill power model an adimensional analysis
Minerals Engineering, 2015Co-Authors: Peter RadziszewskiAbstract:Abstract Stirred Mill power has been modelled empirically, adimensionally and computational intensively through the use of the discrete element method and computational fluid dynamics. To this range of power modelling efforts, one more is added through the development of a shear based power for Stirred Milling. The resulting shear based power model incorporates dimensions of stirrer and chamber geometry as well as operating conditions. In this paper, adimensional analysis, namely Newton and Reynolds numbers, will be used in this paper to explore how this shear based model behaves over a few data sets. A discussion is included on how this model could be improved and used for characterising industrial applications.
E. Kara - One of the best experts on this subject based on the ideXlab platform.
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The Investigation of Grindability of Refractory Wastes in Their Recycling
Refractories and Industrial Ceramics, 2015Co-Authors: A. Dilek Cuhadaroglu, E. KaraAbstract:The ceramic industry is one that stands out in the use of industrial tailings, replacing pure raw materials by some of these materials. Refractory wastes are ground and used in certain proportions in refractory production. This study is aimed at determining the grindability of recycling of refractory wastes and their kinetic behavior. The breakage behaviors were determined experimentally by using the mono-size fraction technique. The mono-size samples of –2360 + 1700 μm, –1180 + 850 μm, and –425 + 300 μm were ground batchwise for the selected periods to determine the Si. At the end of each grinding period, using the material at different mono-size groups, we determined the particle size distributions and breakage behaviors of the products. Depending on the grinding periods in both of the Mills, energy consumption and d80 values of grinding products obtained by various grinding periods were determined. It was found that as the size group decreases, the breakage speed decreases in the ball Mill and increases in the Stirred Mill. An increase in the grinding period results in an increase in energy consumption, but there is no significant change in d80 size in grinding of refractory waste in the ball Mill. However, it was found that d80 size decreases significantly with increasing grinding period in the Stirred Mill.
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The investigation of breakage kinetics of vitrified sanitary ware wastes in laboratory scale ball and Stirred Mills
Particulate Science and Technology, 2015Co-Authors: A. Dilek Cuhadaroglu, E. KaraAbstract:ABSTRACTThis study is aimed to determine the grindability and kinetic behavior on grinding of vitrified sanitary ware wastes. The specific rates of breakage (Si) and the model parameters were determined through kinetic experiments to understand the grinding mechanisms of vitrified wastes. The breakage behaviors were determined experimentally by using mono-size fraction technique. The mono-sized samples of −2360 + 1700 µm, −1180 + 850 µm, and −425 + 300 µm were ground batchwise for the selected periods to determine the Si. At the end of each grinding period, using the material at different mono-size groups, particle size distributions and breakage behaviors of the products were determined. Depending on the grinding periods in both of the Mills, energy consumptions and d80 values of grinding products obtained by varying grinding periods were determined. It was acquired that as the size group decreases breakage speed gets slower in the ball Mill and increases in the Stirred Mill. An increase in the grinding ...