Abstract
Al2O3-Cr2O3-CaO castables have been regarded as ideal linings for various furnaces owing to sufficient strength and excellent corrosion resistance. However, formation of toxic Cr(VI) is the common failing. The present work aimed at achieving in situ detoxification by introducing zeolite. The influence of zeolite on phase evolutions, mechanical properties and Cr(VI) formation were investigated. The results showed that leaching Cr(VI) at 110 °C was lowered by zeolite due to absorption, while chemical reduction of CaCrO4 and Ca4Al6CrO16 occurred at 500−1100 °C and 900−1300 °C, respectively. At 1300−1500 °C, zeolite promoted formation of (Al,Cr)2O3 solid solution (+3 state). Besides, after substituting partial cement with zeolite, CMOR of castables at 110 °C just decreased slightly due to Ca2(Al2SiO6)(OH)2 formation while at 1100−1500 °C, CMOR increased obviously because of enhanced densification. A comparable CMOR up to 68 MPa and a remarkable Cr(VI) detoxification rate of 96.3 % could be achieved for castables with zeolite.
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