Probing the whole ore chalcopyrite–bacteria interactions and jarosite biosynthesis by Raman and FTIR microspectroscopies

The whole ore chalcopyrite–bacteria interaction and the formation of the extracellular polymeric substances (EPS) during the bioleaching process by microorganisms found in the mine of Hellenic Copper Mines in Cyprus were investigated. Raman and FTIR microspectroscopies have been applied towards establishing a direct method for monitoring the formation of secondary minerals and the newly found vibrational marker bands were used to monitor the time evolution of the formation of covellite, and the K+ and NH4+-jarosites from the chalcopyrite surfaces. The Raman data indicate that the formation of K+-jarosite is followed by the formation of NH4+-jarosite. The variation in color in the FTIR imaging data and the observation of the amide I vibration at 1637 cm−1 indicate that the microorganisms are attached on the mineral surface and the changes in the frequency/intensity of the biofilm marker bands in the 900–1140 cm−1 frequency range with time demonstrate the existence of biofilm conformations

Alleviation of organic solvent inhibition with improved copper recovery from low grade sulphide ore by bioaugmentation with newly isolated Candida sp. OR3 and OR6

All rights reserved.Organic compounds used in solvent extraction (SX) processes severely inhibit copper bioleaching microorganisms. In this experimental study, it was found that bioleaching microorganisms at 0.5% and 0.75% organic (SX) resulted in lower Cu recovery from low grade sulphide ore. Two new Candida species OR3 and OR6 were isolated from the liquid phase in solvent extraction process and these isolated strains were tolerant and capable of growing on 1% organic phase. The inhibition of organic phase to bioleaching microorganisms was alleviated by the addition of the 2 isolates and as a result the Cu recovery remained at high level. This is the first study which shows that the organic SX mixture inhibition to acidophilic microorganism can be overcome by the addition of other microorganisms