Abstract: A new method of Zinc recovery from wastewater of Indium extraction was investigated by adding pyrite concentrate with assist of controlling pH value and using ultrasonic，where sulfur ion has a sedimentation effect on Zn.The results showed that when pH value is 2，sulfur concentrate dosage is as 1.5 times as the theoretical one at normal temperature and 50min ultrasonic wave with frequency of 140 kHz and power of 150 W，Zn concentrate grading of 50.36% at a 95.29% recovery was obtained from wastewater of indium extraction with Fe content of 61.23 g/L and Zn of 28.23 g/L in a Guangzhou smelter.Compared with ultrasound-assisted and non-ultrasound-assisted effects，the former can make Zn recovery and Zn grade increased by 23.67 % and 18.52 % respectively with zinc concentrate more uniform and the particle size significantly reduced.

Key words: Indium extraction wastewater, Zinc recovery, Sulphur concentrate, pH value, Ultrasonic wave