Interfacial Interaction Of Solvent Extraction Organics With Sulfide Minerals And Its Impact On Copper Bioleaching

The copper solvent extraction(SX)orgaincs can contaminate bioleaching system through recycling use of the raffinate,which may impact the growth and bioleaching ability of bacterias.The influence of SX organics on the bacterial was mainly studed through evaluating the growth and bioleachig efficiency.However,the interfacial interaction between SX orgaincs and minerals and its impact on bioleaching was not reported until now.This thesis focused on the interfacial interaction of SX organics and minerals in bioleaching process by detecting from the changes of mineral contact angle and ?-potential,following with the study on adsorption kinetics and isothermal equilibrium of organics.By using X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),the product in bioleaching process were analysis.At last the column bioleaching experiment was conducted.The results were as follows:(1)The hydrophobic of mineral increased with the increase of LIX984N concentration.Contaminated by SX organics of LIX984N 2.5%(v/v),the contact angles of high-purity chalcopyrite,low-grade chalcopyrite and waste ores changed from 54°,35°,36° to 80°,63°,62°,respectively.The negative ?-potential of low-grade chalcopyrite ore decreased after being contaminated by SX organics.The influence on ?-potential with different LIX984N concentration of SX organics was not significant,which may resulted from the saturated adsorption.(2)The adsorption capacity of SX organics on minerals increased with time and came to balance in 30 min.The maximum adsorption amount increased with the increase of LIX984N concentration.The secondary order equation fitted adsorption kinetics better and isothermal equilibrium adsorption was fitted better by Langmuir Model at 30?.Isothermal adsorption capacity decreased with the increase of solution pH and temperature.Thermodynamic analysis indicated that the adsorption was an spontaneous exothermal process.(3)The adsorption behavior of three kinds of bioleaching bacterias on SX organics contaminated minerals indicated that,after the surface of ores were contaminated by SX organics,on which the adsorption of At.ferrooxidans?At.thiooxidans?L.ferriphilum were prolonged by 4 min,3 min,10min,respectively.The adsorption capacity of bacteria on contaminated minerals was larger than on uncontaminated ores.The secondary order knietic equation fitted better of the adsorption behaviors of these three kinds of bacteria.(4)The bioleaching process by these three microorganisms under the influence of SX organics indicated that,the bioleaching efficiency of At.ferrooxidans,At.thiooxidans and L.ferriphilum decreased in turn in the control.For the bioleaching of contaminated ores,the growth of three kinds of bacterial cells were inhibited and resulted in decreased bioleaching efficiency.The solution pH was higher and the potential was lower for contaminated ores bioleaching than that of the uncontaminated ores.Besides,under the influence of SX organics,the ferrous iron oxidation by At.ferrooxidans and At.thiooxidans was inhibited for 3 and 4 days,respectively.Furthermore,the Fe2+-oxidation by L.ferriphilum was blocked almost all time.By SEM measurement,more fine particles and slag powder were observed aggregaling at the SX organics contaminated ores' surface,also more cells were observe.XPS and XRD detected that CuFeS2 in minerals had broken down in bioleaching and FeOOH and jarosite were formed.(5)In the tests of transfer and sepration of SX organics in columns,by 18 times of dipping,the SX organics can pollute the surface from top to bottom with the flow of the leaching solution.In column pre-leaching of contaminated and uncontaminated low-grade chalcopyrite ores,both the solution pH and the ORP was nearly equal.The organics resisted the oxidation of ferrous iron and kept its concentration increase to 1.37 g/L at the end,but it went down to 0.48g/1L at the pre-leaching end for uncontaminated leaching.During the next bioleaching process,SX organics impacted the growth of bacteria and resulted in a low leaching efficiency.The solution pH was higher and the ORP was lower for contaminated mineral bioleaching than the uncontaminated ores.The copper bioleaching efficiency was calculated to be 8.2%and 6.9%at the end for uncontaminated and contaminated ores,respectively.By SEM analysis,some small smooth coatings and secondary columnar crystallinities were observed at the surface of contaminated ores.