DefinePK

Abstract

An increase in the carbon content in cast iron and steel during melting is obtained by means of adding carbonaceous materials–carburizers (carburizing agents) to furnace charge [1-5]. To optimize the fastest and complete carbon recovery a carburizer should have a minimal level of impurities and low-ash content. As the ash content of the carburizer decreases, the amount of bottom slag also decreases, which, in turn, increases the durability of the furnace lining. To avoid excessive sulfur saturation of cast iron, the carburizer must contain a minimum amount of sulfur [6, 7]. Currently, coals and natural graphites as carburizers find wide application [1–5]. In comparison with other carbonaceous materials, natural graphites are currently of limited use because of their high sulphur content, which is presented by pyrite (polysulfide form) or available in the sulfide form presented by inclusions and sinters of 2×1 mm in size. Due to the fact that the graphite raw material was formed of sapropelic coals, the mineral components are unevenly distributed within the bulk of the ore in the form of attachments to the main carbon material and micron-sized siltstone. This explains the position of the process men, based on the fact that graphite ore is difficult to enrich, including sulfur [8, 9]. The efficiency of removing sulfur compounds from graphite depends on numerous factors, the main ones being the physical and chemical characteristics of sulfides (crystal structure, stoichiometric composition, magnetic susceptibility, etc.); the total content and ratio of various types of sulfur in graphite; the nature and form of inclusions of sulfides in graphite; the distribution of sulfur compounds according to size classes; the degree of disclosure of iron sulfides attachments to graphite during grinding, crushing; the accuracy of separation in enrichment processes; applied equipment and desulfurization technology [10]. The objective of this paper is to develop technologies for graphite desulfurization, which allows reducing the sulfur content to 0.05 %.