Steel slag is a large amount of residual material produced in the process of steel manufacturing. With the requirements of sustainable development in China, the utilization of steel slag has become a hot issue. Through an in-depth study on steel slag, it is apparent that it has been widely used in various fields in recent years. The resource utilization of steel slag is not only conducive to resource conservation, but also conducive to sustainable production and environmental protection. In this paper, the common ways of resource utilization of steel slag in construction, agriculture, industry, and catalysis are reviewed. Steel slag as a solid waste with great development potential and large output is expected to be widely developed into high value-added products such as catalytic material in the future.

Dicalcium silicate is one of the main mineral phases of steel slag. Ascribed to the characteristics of hydration and carbonation, the application of slag in cement production and carbon dioxide sequestration has been confirmed as feasible. In the current study, the precipitation process of the dicalcium silicate phase in steel slag was discussed. Meanwhile, the study put emphasis on the influence of different crystal forms of dicalcium silicate on the hydration activity and carbonation characteristics of steel slag. It indicates that most of the dicalcium silicate phase in steel slag is the γ phase with the weakest hydration activity. The hydration activity of γ-C₂S is improved to a certain extent by means of mechanical, high temperature, and chemical activation. However, the carbonation activity of γ-C₂S is about two times higher than that of β-C₂S. Direct and indirect carbonation can effectively capture carbon dioxide. This paper also summarizes the research status of the application of steel slag in cement production and carbon dioxide sequestration. Further development of the potential of dicalcium silicate hydration activity and simplifying the carbonation process are important focuses for the future.

Steel slag is the solid waste produced by the steelmaking process. At present, there are differences in the treatment and utilization of this waste among countries around the world. The massive accumulation of steel slag not only occupies land, but also the heavy metal elements in steel slag leached by rainwater cause serious pollution to the soil and groundwater, both which threaten the life and survival of the surrounding residents. More and more attention has been paid to the resource utilization of slag because of the gradual promotion of energy saving and emission reduction all over the world. Currently, the fields that utilize slag focus on recycling of steel waste, acting as sinter raw material, dephosphorization of hot metal, road and water conservancy project construction, wastewater treatment material, application of CO₂ capture and flue gas desulfurization or agriculture. Many researchers have carried out research and explorations on the effects of slag on microalgae’s growth and found that slag has enormous potential algal biomasses and huge advantages for promoting microalgae’s growth and the accumulation of metabolites. Under suitable conditions, slag can effectively promote microalgae’s growth and reproduction, as well as promote microalgae’s accumulation of metabolites, especially lipid accumulation. Thus, slag can be used as an ideal nutrient for microalgae. Culturing microalgae with slag can lower the cost and solve the problem of lacking Fe during the process of marine microalgae’s growth. Meanwhile, it can alleviate the phenomenon of the substantial stacking of slag. This study provides new methods for slag’s resource utilization.

As a by-product of the iron and steel industry, steel slag is rich in catalytically active substances and can therefore be used as a solid catalyst. Many studies have shown that the application potential of steel slag in catalysis is huge, which provides new development space for its application, thereby increasing its additional utilization value. This article primarily reviews the research progress in catalytic fields such as catalytic pyrolysis, organic degradation, electrocatalysis, photocatalysis, transesterification, and carbon capture and storage, as well as the modification methods of steel slag. The catalytic performance of the modified steel slag has been further improved, and it has the meaningful characteristics of high efficiency, cleanliness, and low costs.

As a by-product from the metallurgical industry, steel slag contains a large amount of metal elements. In many developing countries, the output of steel slag is huge and the comprehensive utilization rate is low, hence the development of a novel application method for steel slag is of great significance to increase its utilization rate to improve the environment. This paper reviewed the dissolution behavior of Fe, P, Ca and silicate of steel slag under seawater and acidic solutions as an application in the cultivation of different microalgae, such as diatoms, spirulina, and chlorella. This review clarifies that proper pre-treatment of steel slag can effectively increase the dissolved elements of steel slag in the solution and provide more nutrients for the growth of microalgae. Microalgae cultivated with steel slag as a nutrient can be used to produce biodiesel which has a very broad application prospects for cleaner production and environmental protection.

The bearing steel’s high-temperature brittle zone (1250 °C–1100 °C), second brittle zone (1100 °C–950 °C), and low-temperature brittle zone (800 °C–600 °C) were determined by the reduction in area and true fracture toughness. The crack sensitivity was strongest at temperatures of 1200 °C, 1000 °C, and 600 °C, respectively. Various experimental and computational methods were used to establish the phase type, microstructure, size, and mechanical properties of carbides in bearing steel. The critical conditions for crack initiation in the matrix (FCC-Fe, FCC-Fe, and BCC-Fe)/carbides (striped Fe_0.875Cr_0.125C, netted Fe_2.36Cr_0.64C, and spherical Fe_5.25Cr_1.75C₃) were also investigated. The values for the high-temperature brittle zone, the second brittle zone, and the low-temperature brittle zone were 13.85 MPa and 8.21 × 10⁻³, 4.64 MPa and 6.52 × 10⁻³, and 17.86 MPa and 1.86 × 10⁻², respectively. These were calculated using Eshelby’s theory and ABAQUS 2021 version software. The ability of the three carbides to cause crack propagation was measured quantitatively by energy diffusion: M₃C > MC > M₇C₃. This study analyzed the mechanism of carbide precipitation on the formation of high-temperature cracks in bearing steel casting. It also provided the critical conditions for carbide/matrix interface cracks in bearing steel continuous casting, thus providing effective support for improving the quality of bearing steel casting.