Innovative use of biologically produced ferric sulfate for machining of copper metal and study of specific metal removal rate and surface roughness during the process

The biologically produced ferric sulfate (in the form of bacterial culture supernatant) was used for machining of copper metal workpiece. A 27.04 mg/h cm2 average specific metal removal rate was achieved during oxidation of copper workpiece. The leaching performance of culture supernatant was comparable to that of microbial cells indicating that an indirect non-contact leaching mechanism is predominant for metal solubilization. The surface of copper workpiece was analyzed by scanning electron microscopy before and after oxidation. The changes in surface appearance were found during oxidation of copper. Also the change in surface roughness was observed during machining process. The quality of the surface produced is a very important aspect of the performance of the manufacturing process. Therefore the present study characterizes an effect of various physicochemical parameters on specific metal removal rate and surface roughness. An increasing concentration of FeSO4, shaking speed and volume of culture supernatant showed pronounced effect on metal removal and surface roughness. At the same time an application of varying temperatures showed little effect.