China's Refractories

Abstract: In order to utilize coal gangue and steel slag with high added value, foamed ceramics were prepared by using coal gangue as the main raw material, and steel slag as the auxiliary raw material, adding appropriate amount of flux (talc and potassium feldspar) and foaming agent silicon carbide (SiC). The effects of the steel slag addition (equivalent replacement of coal gangue, 5%, 10%, 15%, 20%, 25%, 30%, and 35%, by mass) and flux addition (fixing the total addition of talc and potassium feldspar at 20 mass%, replacing potassium feldspar with talc in equal amount of 0, 5%, 10%, 15%, and 20%, by mass) on the physical properties, microstructure and phase composition of the foamed ceramics were studied. The results show that: (1) with the increase of steel slag additions, the addition of SiO₂ in the skeleton structure decreases, the addition of CaO, MgO and other oxides increases, and the viscosity decreases; excessive steel slag addition is not conducive to the formation of moderate-size and uniform distributed pores due to the low addition of SiO₂; the steel slag addition shall not exceed 30%; (2) the influence of talc and potassium feldspar flux on the foamed ceramics is mainly to change the contents of alkali metal oxides, as well as Al₂O₃ and SiO₂ which constitute the ceramic skeleton; (3) the optimum foamed ceramic formulation is m(coal gangue) : m(steel slag) : m(potassium feldspar) : m(talc)=50 : 30 : 10 : 10, extra-adding 0.1 mass% SiC.

Key words: coal gangue, steel slag, foamed ceramics, physical properties