Applicability of a New Binder for Ferro-coke Focusing on the Permeation Behavior

Abstract

Ferro-coke, which is produced by mixing coal and iron ore, briquetting and carbonizing, can be used in a blast furnace to greatly decrease the reducing agent ratio. To ensure the strength of ferro-coke, asphalt pitch (ASP) is used as a binder, but the supply of ASP is limited, and the development of alternative binder are required. This study investigated the application of Hyper-coal (HPC), a low-ash caking additive obtained by solvent extraction of coal, as a new binder for ferro-coke. It was found that superior ferro-coke strength could be obtained by using HPC in which insoluble solid concentration was less than 15 wt.%, to that of ASP. This threshold value was specified from the permeation tests. The permeabilities of binders were determined by measuring the permeation distance in the packed layer of coal and/or iron ore under the carbonizing conditions. HPC appeared higher permeability than ASP in the packed layer of iron ore and coal mixtures. It was considered that the excellent thermal plasticity of HPC, lower melting temperature and higher fluidity than ASP, affected higher permeation into the inter particle void especially lower temperature range before starting the reduction of iron ore, which rapidly decreased in the permeabilities of both binders due to the distortion of carbon structures. Those results suggested that HPC was superior to ASP as a binder for ferro-coke.