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    Correlation of the Particle Size Distribution Parameters with Sieving Rate Constant
    (TAYLOR & FRANCIS INC, 2014) Yekeler, M.; Ciftci, M.; Ulusoy, U.; Ozkan, A.
    Controlling the particle size distribution (PSD) of raw materials, intermediates, and end products is very critical to the success of the powder technology related processes. This study presents the evaluation of the sieving characteristics of some industrial minerals, namely, quartz, talc, and barite, and the establishment of possible correlations between the PSD and kinetics parameters. PSD of the -600 mu m fractions of quartz, talc, and barite minerals were plotted in Schuhmann mathematical approach. The size modulus (k(s)) and distribution modulus ((s)) were obtained for each mineral. Then, sieving kinetics study was carried out for each mineral to determine optimum sieving time and sieving rate constant (k(k)). Further, the size distribution parameters were correlated with the sieving rate constant values for those minerals. While distribution modulus ((s)) increases, size modulus (k(s)), and average sieving rate constant values (k(k)) decrease. The correlations were found to be k(s)=-293.52(s)+730.87 and k(k)=-0.0041(s)+0.0454. The results showed that near-mesh particles play important role in the overall kinetic process.
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    Critical oil-liquid interfacial tension for some oil-assisted fine particle processing methods
    (ELSEVIER SCIENCE BV, 2012) Duzyol, S.; Ozkan, A.; Yekeler, M.
    This paper presents that oil-liquid interfacial tension (gamma(OL)) value significantly affects the oil agglomeration and liquid-liquid extraction processes as oil-assisted methods in fine particle processing. The decrease in the oil-liquid interfacial tension leads to the decreases in the recoveries of minerals in both oil agglomeration and liquid-liquid extraction techniques. Eventually, these oil-assisted methods do not take place below a particular value of oil-liquid interfacial tension. The oil-liquid interfacial tension value at which oil agglomeration does not occur was defined as 'critical oil-liquid interfacial tension for oil agglomeration, gamma(c-OL-e)' and at which liquid-liquid extraction does not take place was also defined as 'critical oil-liquid interfacial tension for liquid-liquid extraction, gamma(c-OL-e)' Consequently, the oil-liquid interfacial tension of the medium for successful processes of oil agglomeration and liquid-liquid extraction of a mineral must be higher than the related critical interfacial tension value. (C) 2012 Elsevier B.V. All rights reserved.
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    Kinetics of fine wet grinding of zeolite in a steel ball mill in comparison to dry grinding
    (ELSEVIER SCIENCE BV, 2009) Ozkan, A.; Yekeler, M.; Calkaya, M.
    Batch wet grinding of zeolite was studied with emphasis on a kinetic study in a laboratory size steel ball mill of 200 mm diameter. The breakage parameters were determined by using the single sized feed fractions of -850+600 mu m, -600+425 mu m and -425+300 mu m for the zeolite samples. The S(i) (specific rate of breakage) and B(ij) (primary breakage distribution) values were obtained for those feed size fractions in order to predict the product size distributions by Simulation for comparison to the experimental data. The specific rates of breakage values for wet grinding in the first-order breakage region were higher than the dry values reported previously by a factor 1.7 at the same experimental conditions, but the primary breakage distribution (B(ij)) values were approximately the same. The simulations of the product size distributions of zeolite were in good agreement with the experimental data using a standard ball mill simulation program. The wet grinding of zeolite was subjected to slowing-down effect in the mill at 2 min of grinding, corresponding to an 80% passing size of about 400 mu m. On the other hand. the slowing down effect in the dry grinding of zeolite was also seen at 4 min of grinding. In addition, effects of some operational parameters on dry and wet grinding of zeolite were determined by simulation using the breakage parameters obtained experimentally. (C) 2008 Elsevier B.V. All rights reserved.