Abstract: A self-made nanobubble air flotation device was used as an experimental instrument to simulate the soil heavy metal pollution event caused by the leakage of solution containing Cu²+， Cd²⁺， Ni²⁺， Pb²⁺， Zn²⁺ and Cr³⁺， and the effects of parameters，such as grinding fineness and pH value on the removal efficiency of heavy metal ions were investigated to determine the rapid remediation process of heavy metal contaminated soil by nanobubbles flotation. The results of research showed that when the dosage of ammonium sulfate is 30 kg/t， the dosage of Na2S is 36 kg/t， the dosage of butyl xanthate is 2 500 g/t， pH value is 8.0 and flotation time is 60 min， the removal rates of Cu²+， Cd²⁺， Ni²⁺， Pb²⁺， Zn²⁺ and Cr³⁺ in the contaminated soil were 90.08%， 87.92%， 85.95%， 84.77%， 78.85% and 75.58%， respectively after "one roughing and three scavenging". The contents of Cu²+， Cd²⁺， Ni²⁺， Pb²⁺， Zn²⁺ and Cr³⁺in the foam products were 12.01×10⁴ mg/kg， 11.72×10⁴ mg/kg， 11.46×10⁴ mg/kg， 11.30×104 mg/kg， 10.51×10⁴ mg/kg， 10.08×10⁴ mg/kg， respectively， which reached the quality requirements of sulfide concentrate and had comprehensive recovery value. The technological process obtained from the study has guiding significance for the emergency remediation of heavy metal contaminated soil.

Key words:  Heavy metal, Contaminated soil, Nanobubbles flotation, Emergency remediation