Yazar "Yekeler, Meftuni" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim
    Öğe
    Breakage Parameters of Some Minerals and Coals Ground in a Laboratory Size Ceramic Mill
    (Natl Inst Science Communication, 2003) Özkan, Alper; Yekeler, Meftuni; Aydoğan, Salih
    The kinetics of batch dry and wet grindings of calcite, barite, quartz, lignite and anthracite from feeds of sieve size - 425+300 µm has been determined using a laboratory scale ceramic ball mill. The S₁ values obtained were the highest (0.294 min') for anthracite and the lowest (0.071 min¹) for quartz when ground dry. However, the wet grinding of these materials gave higher S, values by a factor of 1.28 for calcite, 1.15 for barite, 1.25 for quartz, 1.11 for lignite and 1.07 for anthracite comparing to the dry S₁ values. The B₁ values also changed for all the materials ground as dry and wet. The simulations of the product size distributions for both first-order and non-first order breakage of the materials ground were in good agreement with the experimental size distributions. There is a relationship between the S, values and the y value of Bij parameter; i.e., S, values increase when y values decrease, indicating that faster breakage rates of top sizes produce more fines in the finer size distribution region (-150 µm),
  • Küçük Resim
    Öğe
    Correlation of the Breakage Parameters With the Critical Surface Tension for Wetting of Barite
    (ELSEVIER SCIENCE SA, 2003) Yekeler, Meftuni; Özkan, Alper
    In this paper, we present a correlation and experimental data for a relationship between the breakage and the wettability for barite mineral. The breakage parameters, which are readily obtained from grinding test, are the specific rates of breakage (S-i) and the fineness value (7) of the primary breakage distribution function (B-i,B-j). The wettability parameter, which is easily obtained from contact angle measurements or flotation tests, is the critical surface tension for wetting of any mineral (gamma(c)). The barite sample studied for the correlations was ground in a laboratory-size porcelain ball mill and tested extensively for wettability using a contact angle goniometer and our newly designed micro-column flotation cell. There is a significant relationship between the S-i and gamma(c) values from our experimental work on the barite sample, where the higher S-j means lower gamma(c), i.e., a mineral was more hydrophobic when it had a higher S-i value, or a more rapid breakage of the top sizes leads to better hydrophobicity or floatability. Another relationship was found between the fineness value (gamma) of the breakage and the critical surface tension for wetting (gamma(c)), which indicates that as the gamma value increases (meaning less fines produced), the gamma(c) increases (meaning less hydrophobicity) based on the contact angle and flotation tests. (C) 2003 Elsevier B.V. All rights reserved.
  • Küçük Resim
    Öğe
    Fine Dry Grinding of Zeolite in a Laboratory Ball Mill
    (Wiley-v C H Verlag Gmbh, 2003) Özkan, Alper; Yekeler, Meftuni
    This paper presents the importance and usage of natural zeolites, which was recently recognized in the industry. Therefore, the grinding properties of natural zeolite were studied with the emphasis on a kinetic study in a ball mill. The experimental mill employed was laboratory sized, 200 mm diameter, 191 mm length, providing a total mill volume of 6000 cm(3), with a total mass of 5.62 kg of steel balls of 25 mm diameter with a charge of 20% of the mill volume and with a rotation speed of 76 rpm. The breakage parameters were determined by using single sized feed fractions of -850 + 600 mum, -600 + 425 mum, and -425 + 300 mum for the zeolite samples. The S-i (specific rate of breakage) and B-i,B-j (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. From the experimental results, S-i values increased as the feed sizes became coarser, i.e., the highest S-i value was 0.85 min(-1) for -850 + 600 mum, while the lowest S-i value was 0.65 min(-1) for -425 + 300 mum feed ground in the mill. The B-i,B-j values obtained for the zeolite sample were gamma = 0.84, phi = 0.61, and beta = 4.25. The breakage parameters obtained showed that the zeolite is broken faster than quartz and slower than calcite and barite in terms of the a(T) values reported previously at the same experimental conditions. 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 slowing-down effect was also seen in the mill after 4 min. of grinding.