Utilization of Air Quenched Steel Slag in Decorative Ceramics with Higher Mechanical Properties

Abstract

Abstract. Air quenched steel slag is much more difficult to utilize than other kinds of steel slag. 50 % percent of air quenched steel slag was used to prepare brown decorative ceramics. Due to the broken (SiO4)n glass network, the optimum sintering temperature decreases with increasing Na2O and MgO, respectively. The major crystalline phase of the samples is diopside (CaMgSi2O6) with minor anorthite phase (CaAl2Si2O8). Due to remelted glass phase, the X-ray diffraction intensity of the samples decreases with increasing Na2O, while the intensity increases with increasing MgO which is beneficial to crystallization of the samples. The bending strength of the samples decreases with increasing Na2O (from 155.3+/-2.49 MPa to 143.1+/-2.01 MPa), while the strength increases with increasing MgO (from 147.4+/-3.44 MPa to 169.4+/-4.04 MPa). The Vickers hardness of the samples shows similar trends with the bending strength. The samples exhibit much better mechanical properties than marble, granite, tile and other similar ceramics reported, and present good chemical resistance. Therefore, The ceramics based on air quenched steel slag may have great potential for applications as building decorative materials, and it provides a promising way for the utilization of air quenched steel slag. IntroductionSteel slag is a kind of intractable industrial waste, which is produced as a byproduct from either the conversion of iron to steel in basic oxygen furnace, or the melting of scrap in electric arc furnace. The chemical composition of steel slag is highly variable depending on the raw materials and production process, and the utilization of steel slag is difficult [1,2]. According to different cooling methods, air cooled steel slag, water quenched steel slag, water sprayed steel slag, air quenched steel slag, etc. are obtained respectively during the cooling process of molten slag. Since air quenched steel slag is very hard, and much more difficult to be ground than air cooled, water quenched or water sprayed steel slag, the utilization of air quenched steel slag is more difficult [3]. So far, there have been no effective ways for largely utilization of air quenched steel slag.Air quenched steel slag contains calcium oxide, silicon dioxide, magnesium oxide and so on, which are the important component of glass ceramics. In recent years, coal combustion ash [4,5], blast furnace slag [6,7], fly ash and filter dusts from waste incinerators [8][9][10], mud from metal hydrometallurgy [11,12], different types of sludge [13,14] and other industrial wastes [15,16] have been used for the preparation of glass ceramics. Khater [17] has reported that glass ceramics based on 56.78 % blast furnace slag were prepared by mixing quartz sand, dolomite, limestone and clay as other batch constituents. The glass ceramics obtained from vitrified sewage sludge have been studied by Bernardo and Dal Maschio [18], and the sample features good mechanical properties and a