Alkaline extraction characteristics of steelmaking slag batch in NH₄Cl solution under environmental pressure

ZHANG Hui-ning(张慧宁)^{1, 2}, XU An-jun(徐安军)^{1, 2}, HE Dong-feng(贺东风)^{1, 2}, CUI Jian(崔健)³

(1. State Key Laboratory of Advanced Metallurgy (University of Science and Technology Beijing),Beijing 100083, China;2. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing,Beijing 100083, China;3. Ningbo Iron and Steel Co, Ltd., Ningbo 315000, China)

Abstract:In order to obtain better carbonation effect, extraction behavior of slag batch is necessary to study. Relevant parameters like selective extraction yield were originally discussed. The relationship between selective extraction yield and conversion ratio was systemically focused on. The results show that alkaline earth metal conversion ratio is changed with leaching time and NH₄Cl concentration by first order exponential, and the maximum conversion for calcium keeps about 68% at 120 min in 0.4 mol/L NH₄Cl solution, while leaching temperature and particle size have a linear effect on conversion ratio. Selective extraction yield of calcium is more than 93%, and the value of Mg is less than 5%. Apparent layer bands of silicon and calcium appear in the surface area through morphology detection of slag after leaching, and the case for 38-75 μm slag batch is more obvious than 75-150 μm slag and slag with larger particle size when leaching in 0.4 mol /L NH₄Cl solution for 90 min at 60 °C.

Key words:steel slag; alkaline leaching; NH₄Cl solution; selective extraction yield; conversion ratio