scholarly journals Kinetics of the dissolution of sand into alkaline solutions: application of a modified shrinking core model

2004 ◽  
Vol 71 (3-4) ◽  
pp. 435-446 ◽  
Author(s):  
A Mgaidi ◽  
F Jendoubi ◽  
D Oulahna ◽  
M El Maaoui ◽  
J.A Dodds
Keyword(s):  
Core Model ◽  
Alkaline Solutions ◽  
Shrinking Core Model ◽  
Shrinking Core ◽  
Kinetics Of

scholarly journals Macerals of Shengli Lignite in Inner Mongolia of China and Their Combustion Reactivity

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Ying Yue Teng ◽  
Yu Zhe Liu ◽  
Quan Sheng Liu ◽  
Chang Qing Li
Keyword(s):  
Activation Energy ◽  
Homogeneous Model ◽  
Optical Microscope ◽  
Core Model ◽  
Shrinking Core Model ◽  
Compact Structure ◽  
Shrinking Core ◽  
Combustion Reactivity ◽  
Combustion Processes ◽  
Kinetics Of

The macerals, including fusinitic coal containing 72.20% inertinite and xyloid coal containing 91.43% huminite, were separated from Shengli lignite using an optical microscope, and their combustion reactivity was examined by thermogravimetric analysis. Several combustion parameters, including ignition and burnout indices, were analyzed, and the combustion kinetics of the samples were calculated by regression. Fusinitic coal presented a porous structure, while xyloid coal presented a compact structure. The specific surface area of fusinitic coal was 2.5 times larger than that of xyloid coal, and the light-off temperature of the former was higher than that of the latter. However, the overall combustion reactivity of fusinitic coal was better than that of xyloid coal. The combustion processes of fusinitic and xyloid coals can be accurately described by both the homogeneous model and the shrinking core model. The features of xyloid coal agree with the shrinking core model when its conversion rate is 10%–90%. The activation energy of fusinitic coal during combustion can be divided into three phases, with the middle phase featuring the highest energy. The activation energy of xyloid coal is lower than that of fusinitic coal in the light-off phase, which may explain the low light-off temperature of this coal.

scholarly journals Kinetics of Pb and Zn leaching from zinc plant residue by sodium hydroxide

2015 ◽  
Vol 51 (1) ◽  
pp. 89-95 ◽  
Author(s):  
M. Erdem ◽  
M. Yurten
Keyword(s):  
Plant Residue ◽  
Core Model ◽  
Diffusion Control ◽  
Shrinking Core Model ◽  
Zinc Plant ◽  
Ash Layer ◽  
Shrinking Core ◽  
Important Amount ◽  
Increasing Demand ◽  
Kinetics Of

In the hydrometallurgical zinc production processes, important amount of hazardous solid extraction residue containing unextractable Zn and Pb is generated. Due to increasing demand of metals and the depletion of high grade natural resources, these types of wastes are gaining great importance in the metallurgical industries. In this study, selective leaching and leaching kinetics of Pb and Zn from zinc extraction residue were investigated. For this purpose; the effects of NaOH concentration, contact time, stirring speed and temperature on the Pb and Zn recovery from the residue were studied. The shrinking core model was applied to the results of the experiments. Leaching results showed that 85.55% Pb and 21.3 % Zn could be leached under the optimized conditions. The leaching of Pb and Zn were found to fit well to shrinking core model with ash layer diffusion control. Activation energy values for Pb and Zn leaching were calculated to be 13.645 and 22.59 kJ/mol, respectively.

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