Refractory material is the basic material of steel industry. Materials industry and steel industry promote each other and develop together. As our economy enters a new normal, a series of new features have emerged in the iron and steel industry: Overcapacity, declining profitability, increased environmental and resource constraints, and more challenges for transformation and upgrading. The new normal of steel industry puts forward new requirements, new thinking and new changes to the refractory industry at the upstream of the industrial chain. The performance and application of refractories have shown features of characterization, diversification, refinement, efficiency, and low consumption in recent years, to which the development of refractory raw materials must adapt and will also evolve towards new trends such as diversification, enrichment, and specialization. 

1. Diversified reflection of new requirements for refractory raw materials 

1.1. New requirements for green environment protection 

1.1.1. Meet requirements for clean steel smelting 

Clean steel smelting has put forward new requirements for reducing and avoiding pollution of hot metal and molten steel by relevant excipients and refractories used for ironmaking and steelmaking. Research and practice have shown that the aluminum-silicon refractories can pollute molten steel, while magnesium materials do not, and materials containing free CaO not only do not pollute, but also have the function of cleaning molten steel. For this reason, sintering and electromelting magnesium-calcium materials containing free CaO with good hydration resistance are favored. 

In order to reduce the carbon pollution caused by carbon refractories to molten steel, it is necessary to reduce the carbon content in carbon composite refractories. And in order to eliminate the side effect of carbon reduction against thermal shock and corrosion resistance, it is necessary to introduce dispersed carbon source, all of which promotes the R&D and production of various nanocarbon sources suitable for refractories such as carbon black, carbon nano-tube, and graphene. 

In order to reduce the effect of tundish working lining on “rephosphorization” of refined molten steel, a low- or non-phosphorus binding system has been developed. 2.1.2 Meet the requirements of “greenization” in steel industry 

Since Cr6 + has carcinogenic effect and chromium containing refractories have been listed as restricted products by the state, it is imperative to replace chromium containing refractories with new low-chromium and chromium-free materials. For example, high-performance magnesium-carbon brick, magnesium-aluminum spinel brick and magnesium-zirconium brick can be used in refining furnaces such as RH to replace traditional magnesite-chrome brick. 

Tar is commonly used as a binding agent for the sludge used in the tap hole, which promotes people to develop new environmentally-friendly binding agent in order to reduce the pollution to the environment during production and use. 

In order to reduce the harm of traditional aluminosilicate refractory fibers to the environment and human body in the process of production, processing, use and installation, and post-processing, biodegradable calcium-magnesium-silicon refractory fibers have been developed and used. 

1.1.3 Meet the requirements for energy conservation and emission reduction in the steel industry 

As an industrial furnace lining material, it is imperative to use energy-saving refractories. In recent years, new materials for energy conservation have been developed and applied, including microporous lightweight mullite based materials, mullite based hollow spheres, lightweight microporous sintered alumina, CA6-MA composite lightweight aggregates, olivine lightweight materials, spinel lightweight materials, nano-porous silica powder and its polymers, etc. 

1.2 Developing economical refractories 

At present, the refractory and steel industries related to the refractory raw material industry chain are in a downturn, and “low bid” has become the direction of this supply chain. On the other hand, some high-grade natural mineral raw materials such as high alumina bauxite are gradually exhausted, resulting in a decreased ore grade and increased quality fluctuations. And the technical route of relying on high-end raw materials to improve performance and cheap raw materials to reduce costs is gradually coming to an end. Guided by this orientation, low-cost and economical refractory raw materials and products will become a general trend. 

Low consumption is the main development direction of economical refractories. The main direction to realize low consumption of raw materials is to expand the use range of natural raw materials, soft burning material and reworked material. To ensure the high-temperature volume stability of refractories, natural raw materials usually need to be sintered at high temperature or electric melted to achieve inferiority and tend to thermodynamic equilibrium as much as possible. This can lead to high energy consumption, but also cause a certain degree of capacity surplus, in a sense, resulting in invisible resources and energy waste. Non-equilibrium raw materials with lower sintering temperatures than traditional sintering can be developed and applied, and even a certain amount of natural raw materials can be directly added to reduce the energy consumption of refractories to a certain extent. 

Previous studies have shown that adding a certain amount of natural raw material to the castable makes a good effect that the heated raw material decomposes and generates gas to form channels, which helps to improve the explosion resistance. Adding raw coal gangue or soft-burned coal gangue to aluminum silicon castable can generate in-situ mullite after heating, which can improve its hot modulus of rupture and loaded softening temperature, improve thermal shock resistance, and also help achieve lightweight of heavy materials. 

Faced with the situation that high grade ore is becoming exhausted and low grade ore is becoming the main source of raw materials, people must reconsider the science, rationality and adaptability of raw materials and product indicators, and optimize the allocation of raw materials, so that they have better and competitive cost performance. And appropriately reducing the content of A12O and volume density in high alumina refractories used in certain non-melt erosion and erosion areas, and relaxing the requirements for impurity content in aluminum silicon refractories used in certain medium-low-temperature areas should be considered.