Investigation of gold leaching from urban mineral resources via ultrasonic enhancement of thiocyanate-hydrogen peroxide system

Thiocyanate (SCN^-) serves as a viable substitute for cyanide in gold extraction, exhibiting toxicity that is 1000 times lower than that of cyanide. This study investigates a rapid ultrasonic-enhanced leaching technique for gold leaching via thiocyanate and hydrogen peroxide system. The leaching behaviors of gold in the thiocyanate solution under various conditions were also evaluated. The results indicated that the redox potential fluctuates between 0.53 to 0.74 V, with a pH value below 4.9, and the SCN^- concentration varies from 0.08 to 0.38 mol/L, the hydrogen peroxide volume exceeds 0.75 mL, the temperature is maintained at 40 ℃, and solid–liquid ratio of 200/25 tablets /mL. Consequently, 94.65 % of gold was leached and the gold complex present in the system are $\mathrm{Au}{\left(SCN\right)}^{2-}$ and ${\mathrm{Au}\left(SCN\right)}^{4-}$. The results presented in this paper establishes a theoretical foundation for the extraction of gold by the thiocyanate method and promoted the development of thiocyanate technology.