Overall Utilization of Ti-Extraction Blast Furnace Slag as a Raw Building Material: Removal of Chlorine from Slag by Water Washing and Sintering

Ti-extraction blast furnace slag (TEBFS) is the metallurgical solid waste generated during titanium extraction by high-temperature carbonization and low-temperature selective chlorination process in China. The high chlorine content in slag restricts its large-scale utilization in engineering materials. To solve this problem, this study comprehensively evaluated the influence of water washing and sintering on the dechlorination efficiency of TEBFS, and the dechlorination mechanism was further analyzed. The results showed that when the liquid/solid (L/S) ratio was 5 mL/g, the washing time was 60 min, and the washing temperature was 80 °C, the minimum chlorine content in the TEBFS was 0.14%, and the leaching efficiency reached 95.98%. The sintering dechlorination experiments showed that when the sintering temperature was 1100 °C and the holding time was 90 min, the chlorine content in roasting slag was 0.03%, and the dechlorination efficiency reached 99.14%. The main phases in the roasting slag were calcium-magnesium feldspar and diopside, among others. By comparison, the energy consumption of sintering was higher, but the dechlorination effect was more pronounced. Therefore, TEBFS as a raw building material may be treated according to the requirements of chloride content in different building materials, which is benefit to the development of metallurgical industry.