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Leaching optimization and dissolution behavior of alkaline anions in bauxite residue 总被引:1,自引:0,他引:1
Xiao-fei LI Yu-zhen YE Sheng-guo XUE Jun JIANG Chuan WU Xiang-feng KONG William Hartley Yi-wei LI 《中国有色金属学会会刊》2018,28(6):1248-1255
Bauxite residue is a highly alkaline waste containing soluble alkaline anions, which can cause environmental concerns. The optimal leaching conditions, distribution of alkaline anions, types of pivotal alkaline anions and their dissolution behaviors were investigated based on the combination of single factors-orthogonal experiments and leaching stage experiment. Using a two-stage leaching, 86% of the soluble alkaline anions
were leached with a L/S ratio of 2 mL/g, at 30 °C, over 23 h. During the first stage of leaching, approximately 88% of alkaline anions were leached from the dissolution of free alkali (NaOH, carbonate, bicarbonate, NaAl(OH)4) with the rest originating from the dissolution of alkaline minerals (calcite, cancrinite and hydrogarnet). Supernatant alkalinity was 69.78 mmol/L with
accounting for 75%. Furthermore, carbonate leaching was controlled by solid film diffusion using the Stumm Model with an apparent activation energy of 10.24 kJ/mol. 相似文献
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《Acta Materialia》2007,55(17):5747-5757
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Calcium sulphoaluminate (3CaO·3Al2O3·CaSO4, abbreviated as C4A3S) was synthesized by sintering at 1375 °C for 2 h with analytically pure carbonate calcium, alumina and dihydrate calcium sulfate. The crystal structure of C4A3S was characterized by XRD, SEM and TEM. Alumina leaching properties in Na2CO3 solution were studied, and the leaching mechanism was investigated by means of Raman spectrum and XRD. The results show that C4A3S has porous morphology. The polycrystallines and single crystals coexist in C4A3S and grow along different directions. The alumina leaching rate of C4A3S is 98.41%, which is higher than that of 12CaO·7Al2O3 under the optimal condition. The aluminum and sulfur elements exist in the leaching solution in the form of
and
, respectively, and the calcium exists as CaCO3 in the leaching residues. 相似文献
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In the first part, an extensive overview is given over the thermodynamic information for the nickel–phosphorus system which is available in the literature. In the second part, phosphorus vapor pressure measurements over nickel–phosphorus alloys are described for which an isopiestic method was employed. Data points were obtained between 33.82 and 44.40 at% P in the temperature interval from 977 to 1325 K. Based on these measurements partial thermodynamic properties and integral Gibbs energy values were determined. The standard molar Gibbs energy of formation of Ni5P4 for the temperature range 977–1042 K was obtained as: 相似文献
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The edge-to-edge matching (E2EM) crystallographic model was used to predict the orientation relationships (ORs) between LaB6 and Al. Three different possible ORs can be predicted between LaB6 and Al, which are
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; and
,
. The prediction results are perfectly confirmed through TEM analysis and prove the nucleation potency of LaB6. The refining efficacy of Al-2La-1B refiner and its influence on the tensile properties were investigated in the as-cast Al-7Si-0.3Mg alloy. According to the results, LaB6 has higher nucleation potency than TiB2, leading to better grain refining efficacy of Al-2La-1B refiner in the as-cast Al-7Si-0.3Mg alloy. Regarding the mechanical performances, tensile properties of the as-cast Al-7Si-0.3Mg casting alloy are prominently improved after addition of Al-2La-1B refiner, due to the refined microstructures. 相似文献
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Christopher M. MacNeill Jian Dai Cynthia S. Day Stephen P. Lazar S. Jarrett Howell Ronald E. Noftle 《Synthetic Metals》2009,159(15-16):1628-1635
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《Acta Materialia》2007,55(6):2173-2182
Three-dimensional simulations of grain growth in thin films containing finely dispersed second-phase particles were performed using a phase field model. The simulations show that although the growth behavior of the columnar grain structures in thin films is essentially two-dimensional, the interaction between the particles and the grain boundaries is three-dimensional. Grain boundaries can therefore more easily break free from the particles than in purely two-dimensional systems, resulting in fewer grain boundary–particle intersections and a larger final grain size. For a given volume fraction fV and size of the particles r, the final grain size increases with film thickness. Moreover, it was found that particles located in the middle of the film are most efficient in pinning grain boundaries. A classical Zener type relation cannot describe these effects. 相似文献