Alteration of metallic microconstituents in petroleum coke by high temperature treatment

Petroleum coke, which is used as a feedstock for the production of graphite electrodes, construction materials, carbides and other products, may contain a limited amount of metallic microconstituents. One of the procedures for separating metals from “carbonaceous materials” is high temperature treatment (HTT). The paper deals with the results of investigation of the content of microconstituents and their chemical compounds in petroleum cokes before and after the high temperature treatment up to 2400°C. One aim of the investigation was to study the kinetics of metal separation induced by HTT. Experimental results show that metallic micro-constituents in the analysed cokes are mainly present as oxides, silicates, sulphates, sulphides, phosphates and carbides. The types of chemical compounds of the metallic microconstituents present in petroleum coke depend not only on the temperature and time of heating but also on the feedstock and on the type and concentration of microconstituents. During high temperature treatment some compounds are transformed to thermally more or less unstable forms thus facilitating partial or complete separation of metallic microconstituents. Of the identified microconstituents, Si, Al, K, Ca, Fe, Ni, Ti, V, Na, S, P, Cu and Cr, all except iron, titanium and vanadium were separated partially or completely by means of the high temperature treatment up to 2400°C.