INFLUENCE OF GALVANIC DIFFERENCE ON GROUND SUPPORT CORROSION: A CASE STUDY

Mining is an integral part of our society, whether through processing fine materials into usable goods or assessing land areas for profitable land use. Minerals and metals found within mines are used in all types of machines and fuel operations, keeping the world running smoothly. With the recent push for green energy, minerals such as nickel and copper are in high demand. When extracting these metal resources an underground mine in Michigan observed high rates of corrosion in areas that have little to no interaction with water or atmospheric agents. This corrosion was impacting the integrity of ground support elements, which are meant to secure the surrounding rock and protect the miners from rockfall hazards. To investigate the cause of the corrosion, three samples were taken from the affected area to help determine if there was a galvanic difference between minerals causing the failures in ground support. Scrapings of the rock were subjected to a powder X-ray diffraction (PXRD) device to assess what minerals may be causing this issue. It was found that three types of graphite were present along with various iron oxides and magnetic minerals such as magnetite and Iron (II/III) oxide. The galvanic difference between the graphite variants and steel is about 0.367 volts, just under the accepted threshold of 0.5 volts that is considered safe for use. Therefore, graphite is shown to be a heavy accelerant of corrosion and due to its galvanic difference with steel, would explain the accelerated deterioration rate of surrounding support. Further testing, monitoring, and alternative ground support options are suggested to mitigate corrosion hazards and track corrosion rates in new developments.