Ultrasonic-Assisted Acid Leaching of Indium from Blast Furnace Sludge

Ultrasonic-assisted acid leaching was used to improve extraction of indium from blast furnace sludge. The effects of solid–liquid ratio, leaching temperature, and leaching time on extraction of indium were investigated and three leaching methods of high temperature acid leaching (HL), ultrasonic acid leaching (UL), and high temperature-ultrasonic acid leaching (HUL) were compared. The results show that extraction of indium increases with leaching time for all the methods. UL exhibits the lowest indium extraction. For HL, extraction of indium reaches 32.6 pct when the leaching time is 4 hours, and after 4 hours, the extraction increases slowly. Leaching temperature has a more positive effect on extraction of indium than ultrasonic. HUL can lead to a higher extraction of indium than high temperature acid leaching and UL, and extraction of indium reaches 40.4 pct when the leaching time is 2 hours. After 2 hours, no obvious increase occurs. HUL not only increases extraction of indium but also reduces the leaching time which can improve production efficiency.