ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
Social and Environmental Engineering
Shear-Force Based Stainless Steel Slag Modification for Chromium Immobilization
Qing ZhaoChengjun LiuLonghu CaoMaofa JiangBaokuan LiHenrik SaxénRon Zevenhoven
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2019 Volume 59 Issue 3 Pages 583-589

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Abstract

Immobilization of chromium in a stable spinel by modification is a powerful way to prevent chromium pollution of stainless steel (SS) slags. The precipitated spinel grain size is usually smaller than 30 µm, however, which limits the effectiveness of the modification. In the literature, very few efforts have been reported on promotion of spinel growth rate by optimizing the dynamic conditions. In this study, the effects of shear force on the spinel grain size evolution under isothermal conditions and during cooling were investigated. The experimental results indicate that the employment of shear force significantly changes the growth behavior of spinel at 1500°C. The growth mechanism of spinel was studied by using crystal size distribution (CSD) theory, showing different regimes of supply-controlled Ostwald ripening, surface-controlled growth with decaying nucleation rate, and constant rate nucleation and growth at shear rates of 0 s−1, 10.83 s−1, and 21.67 s−1, respectively. On the other hand, at a cooling rate of 5°C·min−1, the shear force was found to have little effect on the crystallization behavior of spinel. The results of static leaching tests indicated that hardly any chromium had leached, which makes the modified SS slag more environmentally friendly when used as a raw material.

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© 2019 by The Iron and Steel Institute of Japan
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