磁处理提高广东某含铜金矿金浸出率的试验研究

广东某含铜浮选金精矿的金品位为8.312 g/t、铜含量为5.18%，工业上采用全泥氰化、浸出渣浮选回收铜的工艺流程。矿石中较高的铜含量不仅消耗大量的氰化物，还影响了金的浸出效果。为了进一步提高金的浸出率、降低氰化物用量，采用加温常压化学预氧化浸铜—浸铜渣氰化浸金工艺回收试样中的铜和金，并在磁处理条件下，考察了磁场强度、磁化时间、起始硫酸浓度、NaCl浓度、浸出温度和浸出时间等因素对金、铜浸出率的影响。试验确定磁处理的最佳条件为：磁场强度150 kA/m，磁化时间50 min，磨矿细度-200目占88%，预氧化温度93 ℃，起始硫酸浓度0.77 mol/L，NaCl浓度0.76 mol/L，预氧化时间27 h。在此条件下进行氧化预处理浸铜及铜渣氰化浸金试验，固定搅拌强度为760 r/min，液固比为3∶1，氧气流量为160 mL/min，氰化钠用量为7 kg/t，铜和金的浸出率分别为85.76%、98.86%。较未进行磁处理的最佳指标（铜浸出率71.28%，金浸出率86.26%）相比，铜浸出率提高了14.48个百分点，金浸出率提高了12.60个百分点；此外，预氧化温度降低了2 ℃，预氧化时间减少了1 h，氰化钠用量减少了3 kg/t。研究结果表明磁处理能有效提高含铜金矿的铜、金浸出率，减少有毒氰化物的用量。

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

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.