Chemical interaction between basic sinter and Newman Blend Lump analogues

The softening and melting (S&M) behaviour of ferrous burden materials is of great importance as it controls the formation of the cohesive zone and affects the stable operation of the blast furnace. It has been shown that both physical and chemical interactions exist between Newman Blend Lump (NBLL, a high grade hematite goethite Australian lump ore) and a basic sinter in the S&M process. The S&M behaviour of a ~20% NBLL - sinter mixture was significantly improved by the interactions, resulting in a narrower S&M temperature zone with a higher permeability than that for either of the individual burdens. It was found previously that the basic sinter transferred Ca and Mg to neighbouring NBLL particles before 1450 ℃ in the S&M under load test. In this study, a Coal Ash Fusion (CAF) furnace was used to investigate the mechanism and influencing factors for the chemical interaction between a basic sinter and NBLL using analogues made of crushed raw materials under controlled conditions. It was confirmed that the obvious diffusion of Ca and Mg from sinter to NBLL occurred between 1250 ℃ and 1300 ℃ after 60 min reduction at 900 ℃, once initial melts had formed on both sides, and the mineral compositions of sinter and lump were largely changed by the chemical interaction. In addition, the results also revealed that enough holding time above the melt formation temperature was essential for the chemical interaction.