Making untreated carbon effective in cleaner thiosulfate system: A new and high-efficiency method including gold adsorption and desorption
Compared with the cyanide method, the thiosulfate method is a green and clean gold production method, while gold recovery from thiosulfate solution is pending. Although the activated carbon adsorption method has been highlighted, current studies cannot avoid the complexity of activated carbon modification. This study used thiosemicarbazide (TSC) as the additive of the gold solution, investigating the gold recovery performance of pristine activated carbon and its adsorption mechanism. As a result, even for containing gold 100 mg/L, gold adsorption percentage close to 100% could be achieved on original carbon within 12 h when adding 0.02 g TSC. Next, under the optimal conditions, gold loading amount of 42.6 kg/t was attained after five-stage adsorption. Characterization via XPS , FT-IR, BET, and UV–vis verified the gold adsorption mechanism was related to TSC's decomposition into SCN − under activated carbon's catalysis, the formation of Au(SCN) 2 - and whose adsorption on the surface of original carbon. Furthermore, it was found that this method exhibited well gold recovery ability (99%) for gold in both Cu 2+ -en-S 2 O 3 2− and Cu 2+ -NH 3 -S 2 O 3 2− solutions; Additionally, well gold recovery performance (99%) was also achieved for two leaching solutions (Au: 35 and 42 mg/L, Cu 2+ : 3178 mg/L) of an actual ore. Last, gold desorption studies indicated that a good gold desorption rate of 95.3% was achieved within 24 h for carbon containing 5 kg/t of gold when using N, N-dimethylformamide (DMF) as desorbent . This paper gifted untreated activated carbon with excellent adsorption ability towards gold in thiosulfate system for the first time, which is meaningful for the cleaner production gold.
危险品化学品经营许可证（带存储）