Development of thermal pretreatments of chalcopyrite concentrates with microwave to enhance oxidation leaching

2007 Fiscal Year Final Research Report Summary

• Project/Area Number: 18560715
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Metal making engineering
• Research Institution: Kyushu Institute of Technology
• Principal Investigator: ITOU Hideyuki Kyushu Institute of Technology, Faculty of Engineering, Assistant Professor (90213074)
• Co-Investigator(Kenkyū-buntansha): TAKASU Tomio Kyushu Institute of Technology, Faculty of Engineering, Associate Professor (20264129)
• Project Period (FY): 2006 – 2007
• Keywords: Microwave / Chalcopyrite / Copper Concentrate / Thermal pretreatment / Leaching / Redox Potential

Research Abstract

In order to enhance extraction of Cu from chalcopyrite concentrates, thermal pretreatments in Ar atmosphere were carried out on a reference chalcopyrite mineral and various chalcopyrite concentrates. Composition and X-ray diffraction were analyzed for the samples. Leaching experiments with CuCl_2 and Fe_2 (SO_4)_3 solutions were conducted. Application of microwave to the pretreatments for the leaching was also examined. Following results were obtained.
Chemical compositions differed among the concentrates from different localities. However, XRD results for the every sample showed intensive peaks of chalcopyrite (CuFeS_2) and weak peaks of quartz (SiO_2).
Thermal pretreatment on the concentrates above 700℃ using an electric resistance furnace caused a shift in the main peak position of chalcopyrite around 2θ=29deg. It accompanied volatilization of small amount of sulfur and the structure of chalcopyrite changed from α type to β type. Formation of Bornite (Cu_5FeS_4) was also observed.
Increases in Cu extraction ratio with CuCl_2 and Fe_2(SO_4)_3 solutions was achieved by the pretreatment of the concentrates using the resistance furnace. For the case of CuCl_2 solution, small effect of the pretreatment was observed only during initial 2 hours for leaching temperature at 80 and 90℃. For the case of Fe_2 (SO_4) _3 solution, the extraction ratio increased with the pretreatment and the effect of the pretreatment was more significant for leaching temperature at 80 and 90℃ than at 40℃.
The thermal pretreatment using microwave showed the same tendency to the pretreatment using the resistance furnace. Change in the chalcopyrite structure from α type to β type and formation of Bornite were confirmed. The extraction ratio of Cu increased with the pretreatment.
Since the extraction ratio of Cu did not show significant difference due to the thermal pretreatment methods, the thermal pretreatment even with shorter time was found to be effective in order to enhance the leaching of Cu.