Study On Ultrasonic Enhanced Leaching Of Copper And Gold

Leaching is the controlling step in the process of hydrometallurgy, so it has important practical significance to strengthen the leaching process. Ultrasonic-assisted leaching provides a new and special physical environment for difficult or impossible reaction under conventional conditions, opens a new reaction channel, weakens leaching conditions of strong acid, strong alkali, high temperature, high pressure, toxic and others in a certain extent, improves the recovery rate of metal, especially in leaching low grade and difficult mineral.The conventional method of removing copper in company has many shortcomings, such as low copper removal efficiency, high content of copper in leaching residue and the recovery of precious metals and valuable metal seriously affected with tellurium into the solution. In addition, having difficult to leach gold from refractory ore, slow leaching speed and vulnerable affected by impurity (such as copper, iron, lead, zinc, sulfur and arsenic) and poison with cyanidation. Focusing on these weaknesses, the thesis produced ultrasound-assisted leaching copper and gold, and analyzed the influence of ultrasonic on composition and morphologymineral of minerals.Firstly, the copper anode slime of a copper company of Yunnan was as the research object.The sulfuric acid concentration, reaction time, liquid-solid ratio and ultrasonic power were researched, and the industrial experiment was carried out. The results showed:at the conditions of solid-liquid ratio of 4:1, sulfuric acid concentration of 175g/L, ultrasonic power of 800W and leaching time of 10h,3.15% Cu was contained in residue. Requirement of the copper slag of copper less than 5% and the optimal value (≤3.5%) were reached. Leaching time reduced from 24 hours to 10 hours. Industrial experiment proved that ultrasound-assisted leaching copper from copper anode slime is feasible, and the content of copper in residue is 2.97% after leaching 0.5h.Secondly, ultrasound-assisted leaching of gold from a refractory gold ore of a gold company of Yunnan as conducted and effects of solid-liquid raito, leaching time, ultrasonic power, lixiviant concentration, NaCl concentration and NaOH concentration on the leaching rate were investigated. Results showed the best conditions for gold leaching were as follows:NaCIO concentration of 1.5mol/L, NaOH concentration of 1.5mol/L, NaCl concentration of lmol/L, solid-liquid ratio of 5, ultrasound power of 200W and sonication time of 2h. With the optimal conditions,68.55% of gold was extracted. However, only 45.8% of gold was extracted after leaching 6h by no-ultrasound-assisted leaching under optimal conditions. Results proved that ultrasound-assisted leaching cound improve extraction rate and reduce leaching time.The SEM-EDS, XRD and theoretical analysis were used to analyze the influence of ultrasonic on composition and morphologymineral. The results showed that under ultrasonic activation, product layer can be peel, new surfaces was expose, reaction resistance was reduced the, liquid-solid reaction was promoted and reaction speed was greatly improved.