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    Correlations of Bond and Breakage Parameters of Some Ores with the Corresponding Point Load Index
    (WILEY-V C H VERLAG GMBH, 2012) Aras, Ali; Ozkan, Alper; Aydogan, Salih
    This paper presents significant correlations of the Bond parameter (work index, Wi and grindability, G) and the breakage parameters (specific rate of breakage, Si and the fineness value, ?) with the point load index (Is(50)). The experimental results obtained from calcite, barite, colemanite and bauxite samples have demonstrated that the Bond and breakage parameters were closely correlated with the point load index. That is, the values of G, Si and aT parameters decreased with the increase in the values of the point load index; however, the ? parameter of Bi,j increased with increasing Is(50) values.
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    Dissolution kinetics of galena in acetic acid solutions with hydrogen peroxide
    (ELSEVIER SCIENCE BV, 2007) Aydogan, Salih; Aras, Ali; Ucar, Goekhan; Erdemoglu, Murat
    The kinetics of leaching lead from galena in acetic (ethanoic) acid solutions with hydrogen peroxide are investigated with regard to stirring speed, temperature and concentration of HAc and H(2)O(2) concentration. Oxidation of galena with H(2)O(2) to produce lead sulphate which dissolves by complexing Ph(2+) with acetate anion (PbCH(3)COO(+) and Pb(CH(3)COO)(2)). Results indicate that the rate of galena dissolution is controlled by a surface chemical reaction with an apparent activation energy is 65.6 kJ mol(-1)I in the temperature range 30-70 degrees C. Both HAc and H(2)O(2) affect the rate of extraction of lead as an acetate complex. The order of reaction was 0.79 and 0.31 for H(2)O(2) and HAc concentrations, respectively. (C) 2007 Elsevier B.V. All rights reserved.
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    Effects of intensive grinding on the dissolution of celestite in acidic chloride medium
    (PERGAMON-ELSEVIER SCIENCE LTD, 2009) Erdemoglu, Murat; Aydogan, Salih; Gock, Eberhard
    Effect of intensive grinding on the dissolution of celestite in acidic barium chloride and sodium chloride solutions was studied by investigating structural changes occurred during milling. Complete dissolution of the celestite was achieved within 25 min by milling in a planetary ball mill in which ball to ore ratio is 10. But, increasing grinding time and ball to ore ratio diminished the dissolution rate. X-ray amorphous phase content and XRD breadths increased and XRD line reflection intensity decreased with increasing of grinding time, and celestite does not undergo a considerable phase transformation during milling. SEM micrographs showed that how prolonged milling results in an increasing degree of agglomeration and a reduced amount of fines. Additionally, the ground samples were heated at elevated temperatures and then re-ground under earlier grinding conditions. Structural, morphological and dissolution characteristics of the samples obtained by each of the three treatments were also evaluated. It was concluded that high energy milling for short times increases the dissolution rate of celestite. But, increase in the particle size due to agglomeration or compactness of the particles as a result of impact stress predominant in planetary ball milling decreased the leaching rate, as grinding time and ball to ore ratio in the mill were increased. (C) 2008 Elsevier Ltd. All rights reserved.
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    A kinetic study on the conversion of celestite (SrSO4) to SrCO3 by mechanochemical processing
    (ELSEVIER SCIENCE BV, 2007) Erdemoglu, Murat; Aydogan, Salih; Canbazoglu, Mehmet
    The direct conversion of celestite (SrSO4) to Strontium carbonate by mechanochemical processing was studied under wet milling conditions by varying the amount of sodium carbonate with respect to the stoichiometric amount required for the conversion reaction. The effect of solid to liquid ratio and change of particle size distribution during the milling were examined. The resulting conversion-time curve was fitted using the shrinking particle model. It was observed that celestite completely converted to strontium carbonate within 45 min, when the solid to liquid ratio was 0.1. With 50% excess sodium carbonate was used at a solid to liquid ratio of 0.2 the apparent rate constant was 0.0131 min(-1), at a solid to liquid ratio of 0.1 the rate was 0.0211 min(-1). The order of mechanochemical conversion was proportional to the 1.21 power of the CO32- concentration. (C) 2006 Elsevier B.V. All rights reserved.
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    Kinetics of galena dissolution in nitric acid solutions with hydrogen peroxide
    (ELSEVIER SCIENCE BV, 2007) Aydogan, Salih; Erdemoglu, Murat; Ucar, Goekhan; Aras, Ali
    The extraction of lead from a galena concentrate in nitric acid solutions with additional hydrogen peroxide was studied taking stirring speed, temperature, hydrogen peroxide and nitric acid concentrations, and particle size as dissolution parameters. The dissolution curves followed the surface chemical reaction controlled shrinking core model over the whole range of parameters, except at high nitric acid concentrations where the reaction was diffusion-control led. The activation energy of 42 KJ mol(-1) and a linear relationship between rate and inverse particle size support the reaction controlled dissolution mechanism. Hydrogen peroxide addition accelerated the reaction compared with nitric acid alone. It was concluded that the dissolution process is favourable, since the acid consumed for oxidation of galena can easily be regenerated in the same reactor by means of hydrogen peroxide. (c) 2007 Elsevier B.V. All rights reserved.