Properties and application of carbon composite brick for blast furnace hearth

Abstract

A type of carbon composite brick was produced via the microporous technique using natural flack graphite, ?-Al2O3 and high-quality bauxite chamotte (Al2O3?87 mass%) as raw materials with fine silicon powder as additive. The composition and microstructure of the obtained carbon composite were characterized using chemical analysis, XRD and SEM with EDS. The high temperature properties of thermal conductivity, oxidization and corrosion by molten slag and hot metal of the composite were analyzed. Based on these, the type of carbon composite brick worked in a blast furnace hearth for six years was further sampled at different positions. The protective layer was found and its chemical composition and microscopic morphology were investigated. It is found that the carbon composite brick combines the good properties of both the conventional carbon block and ceramic cup refractory. The protective layer near the hot face consists of two separated sublayers, i.e. the slag layer and the carbon layer. A certain amount of slag phase is contained in the carbon layer, which is caused by the reaction of coke ash with the refractory. No obvious change in the chemical composition of the protective layer along the depth of the sidewall is found. This work provides a useful guidance for the extension of the lifetime of blast furnace hearths.

Analysis of Blast Furnace Hearth Sidewall Erosion and Protective Layer Formation

“…A number of studies have investigated the hearth erosion of the BF, but the information on the composition and the microstructure of lumped skull lining material are still very limited. [7][8][9][10][11][12][13][14][15][16] An improved understanding of the skull formation and the wear…”

Circulation and accumulation of harmful elements in blast furnace and their impact on the fuel consumption

“…However, the extent of the accumulation of each individual elements and their effect on fuel consumption in BF is still unclear and very few relevant quantified studies have been performed. 20,21 At present, the loads of harmful elements in BF of most iron and steelmaker in China are found to be much higher than those limits. The loads of harmful elements also vary significantly from plant to plant and furnace to furnace.…”

Dissection Investigation of Forming Process of Titanium Compounds Layer in the Blast Furnace Hearth

“…2,3) At present, it is known that the titanium compounds layer with iron-based composite material and graphite is the main component of the protective layer. [4][5][6] However, the process of forming the protective layer of the hearth is a complex process with multiple thermochemical evolution processes. At the same time, excessive addition of titanium-bearing ores will also increase the viscosity of the slag and reduce the permeability of the blast furnace.…”