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Metal Mine ›› 2021, Vol. 50 ›› Issue (05): 120-124.

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Experimental Research on Improving Gold Leaching Rate of a Copper-contained Gold Ores by Magnetization Treatment

CHEN Xiang    LIAO Dehua   

  1. Hunan Nonferrous Metals Vocational and Technical College, Zhuzhou 412006, China
  • Online:2021-05-15 Published:2021-05-12

Abstract: A copper-contained gold flotation concentrate in Guangdong has a gold grade of 8.312 g/t and a copper content of 5.18%. In industry, the technological process of full sludge cyanidation and leaching residue flotation to recover copper is adopted. The higher copper contents in the ores not only consumes a large amount of cyanide, but also affects the leaching effect of gold. In order to further improve the leaching rate of gold and reduce the dosage of cyanide, the copper and gold in the samples were recovered by oxidation at warming and ordinary pressure and cyanide leaching with copper slag. Under the condition of magnetic treatment, magnetic field intensity, magnetization time, initial concentration of sulfuric acid, NaCl concentration, leaching temperature and time on leaching rate of gold and copper were explored. The optimum conditions of magnetic treatment were determined as follows: magnetic field intensity of 150 kA/m, magnetization time of 50 min, grinding fineness of -200 mesh accounting for 88%, pre-oxidation temperature of 93 ℃, initial sulfuric acid concentration of 0.77 mol/L, NaCl concentration of 0.76 mol/L, pre-oxidation time of 27 h. Under the optimal conditions, the oxidation pretreatment leaching of copper and cyanide leaching of copper slag were carried out. The fixed stirring intensity was 760 r/min, the liquid-solid ratio was 3∶1, the oxygen flow rate was 160 mL/min, and the dosage of sodium cyanide was 7 kg/t. The leaching rates of copper and gold were 85.76% and 98.86%, respectively. Compared with the best index without magnetic treatment (the copper leaching rate of 71.28% and the gold leaching rate of 86.26%), the copper leaching rate increased by 14.48 percentage points, the gold leaching rate increased by 12.60 percentage points. In addition, the pre-oxidation temperature decreased by 2 ℃, the pre-oxidation time decreased by 1 h, and the dosage of sodium cyanide decreased by 3 kg/t. The results showed that magnetic treatment can effectively improve the copper and gold leaching rate and reduce the amount of toxic cyanide in copper-contained gold ore.

Key words: copper-contained gold ores, oxidation at warming and ordinary pressure, magnetization treatment, condition tests