The recovery of kish graphite from secondary sources

by Robert Frost

Institution: University of Birmingham
Department: School of Chemical Engineering
Year: 2015
Keywords: TP Chemical technology
Record ID: 1390506
Full text PDF: http://etheses.bham.ac.uk/5704/


With the worldwide demand of graphite increasing, so the availability, cost and quality is under renewed scrutiny - with the vast majority of graphite being mined, and with these mines located in only a few significant countries, considerations of availability and sustainability have led to an increasing dependence on synthetic graphite to meet industrial needs. One potential source is ‘kish’ graphite recovered from the steel making process: Present within the dust produced as waste in steel plants, graphite flakes have been found in varying quantities, sizes and purity. Seven samples taken from a steel plant were analysed and tested. This testing broadly consisted of separating the kish graphite from the excess waste dust, and refining this graphite. Froth flotation was found to be an extremely effective way of achieving this, with purities of >90% being achieved from a single flotation for the larger flake sizes (>500µm). For the smaller flake sizes (<500µm), multiple froth floats were found to be needed in order to achieve the desired purity, but further complications required acid cleaning in order to achieve a >90% graphite sample. A saleable product was produced and a technical-economic assessment was made for a 10,000 tonne per year process plant.