Process And Mechanism Research Of Iodine-iodide Leaching For Refractory Gold Ore Bearing Copper

Along with the development of social economy, the consumption of mineral resoueses becomes more and more. Because of long period utilization, mineral resouses of high grade and easy processed are fewer and fewer. But refractory mineral resources are increased. It is the same situation for gold resourse. In the paper, the refractory gold ore bearing copper was investigated using iodine-iodide leaching as the method of recycling gold. Thermodynamic calculation was finished to find the principle and regulation of iodine-iodide leaching. Different effects were evaluated to analyse the dynamic of iodine-iodide leaching and leaching rate equation was founded. Meanwhile, the process parameters were optimized through series experiments.Through the research of ore property and process mineralogy, the gold ore belongs to the refractory gold ore bearing copper. The oxygenation efficiency of copper is90.33%. Several different process are finished such as cyanidation, flotation-cyanidation, LSSS, iodine-iodide leaching. The results show gold could be selectively extracted by iodine-iodide leaching, meanwhile, the recovery is pretty high.The optimized process parameter is obtained through series experiments. The parameters as below:iodine concentration is0.0315mol/L, iodine-iodide mass ratio is1:6, solution pH is7, liquid and solid ratio is4:1, stirring rate is400r/min, leaching time is120minutes, grinding fineness is-0.074mm91%, leaching temperature is25℃Under these conditions, gold recovery reaches88.55%, meanwhile, copper extraction is0.61%. In other words, gold could be selectively extracted by iodine-iodide leaching for the refractory gold ore bearing copper.Through the investigation of thermodynamic research of iodine-iodide leaching based on simultaneous equilibrium principle indicates, it is found that when [Au]T is10-4mol/L, along with the increase of [I-]T, it is better for gold extraction by iodine-iodide. Quantity of solid AuI increases first and then decreases. When [I"]T is10-4mol/L, quantity of solid AuI is maximum. When [I-]T is more than10-4mol/L, solid AuI is disappeared. When lg[I-]T is more than-2.7, the primary metal ion in solution is AuI2-. In total area, the content of AuI4-is nearly zero. Through the dynamic investigation of iodine-iodide leaching, the refractory gold ore bearing copper is extracted under the condition as below:solution pH is7, liquid and solid ratio is4:1, stirring rate is400r/min, leaching time is10～60minutes, grinding fineness is-0.074mm91%. The apparent activation energy is obtained as41.8kJ/mol, iodine-iodide leaching is controlled by interface chemistry reaction. The reaction order of iodine and iodide is1and0.6respectively. So reaction rate equation of iodine-iodide leaching of this refractory gold bearing copper is1-(1-ε)1/3=10.1×e-41800/RT·[I2]1[I-]0.6.Research of this paper could promote the theory and practice research of non-cyanide leaching in China. Meanwhile, it provide a new process for selective gold extraction for refractory gold ore bearing copper.