# Preparation of Steel Slag Ceramics with Different MgO/Al\({}_{2}\)O\({}_{3}\) [PERSON]
## 1 Introduction  
The rapid development of the iron and steel industry in China has resulted in increased steel slag production, accounting for values as high as 10-15% of total annual steel production [1; 2]. For instance, estimated steel production in China in 2017-2018 was around 900 million t, and the corresponding output of steel slag was about 120 million t. At present, the stockpile of steel slag in China has reached approximately 1.3 billion t [3], but the comprehensive utilization rate is only about 22%. Such a large amount of steel slag not only occupies land for storage, but also has adverse effects on the environment, such as leaching of heavy metal ions, causing surface water, groundwater, and air pollution, and eventually threatening human health. Many researchers have devoted efforts toward the comprehensive utilization of steel slag and have made many breakthroughs. Currently, steel slag is used as a resource in the production of cement [4; 5; 6; 7], road, bridge, and water conservancy project construction [8; 9; 10; 11], and production of agricultural chemical fertilizers [12; 13]. It also acts as a replacement to limestone in steelmaking [14] and is used to extract valuable metals [15]. However, these applications fall short of using the entire amount of generated steel slag. Thus, other large-scale reuse methods are still needed. Considering the composition of silicate and amorphous glass phases, such as dicalcium silicate, tricalcium silicate, and so on, in steel slag, it is feasible to use it in ceramic production. In recent years, much research has been conducted on ceramics prepared from solid waste. [PERSON] et al. [16] synthesized mulitte ceramics using fly ash and desiliconized flyash, and tested the physical and mechanical properties of the fired samples. The results showed that desiliconized fly ash is more suitable for the preparation of mullite ceramics. [PERSON] et al. [17] used converter steel slag and clay as raw materials to prepare ceramic bricks and observed good performance with a steel slag content of 20-60%. [PERSON] et al. [18] fabricated ceramic tiles using blast furnace slag as a replacement for limestone and kaolin, and found that the strength of the ceramic tiles was 25% higher than that of ordinary ceramic tiles when the blast furnace slag content was 33%. [PERSON] et al. [19] produced ceramics from inferior clay and high proportions of Fe\({}_{2}\)O\({}_{3}\), CaO, and bauxite tailings. The effects of Fe\({}_{2}\)O\({}_{3}\) and CaO were also investigated. Their findings indicated that Fe\({}_{2}\)O\({}_{3}\) helps lower the firing temperature and promotes the densification process, whereas CaO is beneficial to the creation of anorthite and pyroxene at low temperatures. Using 30% steel slag content, [PERSON] et al. [20; 21] prepared steel slag ceramics with flexural strength and water absorption of 107 MPa and 0.045%, respectively. The influence of Fe\({}_{2}\)O\({}_{3}\), CaO, and Al\({}_{2}\)O\({}_{3}\) on the performance, crystallization process, and densification process of steel slag ceramics was also studied. The results demonstrated that both Fe\({}_{2}\)O\({}_{3}\) and CaO are beneficial to the processes of liquid phase sintering and densification. Al\({}_{2}\)O\({}_{3}\) is first involved in the formation of anorthite, followed by the disappearance of the anorthite phase into the liquid phase, and finally, solid solution into the pyroxene phase. [PERSON] et al. [22] prepared steel slag ceramics with different MgO contents, and studied the influence of MgO on sintering temperature and crystal phase. Considering the influence of Al\({}_{2}\)O\({}_{3}\) and MgO on the crystal phase and mechanical properties of ceramics, steel slag ceramics with different MgO/Al\({}_{2}\)O\({}_{3}\) ratios were prepared in this study by changing the Al\({}_{2}\)O\({}_{3}\) and MgO contents. The effects of the MgO/Al\({}_{2}\)O\({}_{3}\) ratio on the crystallization behavior, microstructure, and major mechanical properties were investigated.