Reaction kinetics calculation of low grade sulphur concentrate roasting under oxygen enrichment
ZU Gang,LI Jie,LI Bao- wei,WANG Jie- liang,YANG Zhong- yu
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Key Laboratory of Integrated Exploitation of Bayan Obo Multi- Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010, Nei Mongol, China
For the problem of desulfurization from sulphur concentrate, the reaction kinetics process of low grade sulphur concentrate roasting under oxygen enrichment was studied, and the changes of mineral phases in sulphur concentrate roasting during the course of oxidation were analyzed by SEM, XRD and EDS. At the same time, according to DSC and TG curves, the kinetic parameters of desulfurization reaction were calculated by Achar- Brindley- Sharp- Wendworth differential method and Coats- Redfern integral method, and the desulfurization mechanism of sulphur concentrate was determined at different temperature stages. The results show that with the rising temperature, the complex sulphur concentrate gradually becomes hematite, accompanied by the formation or the decomposition of the intermediate ferric sulfate; and sulfur content of roasting ores decreases. The kinetics calculation results show that in the temperatures of 430－975℃, oxidation roasting of sulfur concentrate has four temperature stages. In the first three stages, desulfurization reaction mechanisms all accord with Avrami- Erofeev equation, belonging to the chemical reaction control of the random nucleation and then growth, only the reaction order and the apparent activation energy of reaction vary in different temperature stages; In the fourth stage, the desulfurization reaction mechanism accords with Z- L- T equation, belonging to the reaction control of the three- dimensional diffusion of the residual sulphide. In addition to this, the apparent activation energies of reaction are 10. 812 and 9. 920kJ/mol respectively, and are the lowest in four temperature stages.
