In the paper, it is elaborated the inherent difficulties and advantages for comprehensive utilizations of resources in Bayan Obo ore deposit, proposed several problems noteworthy of better comprehensive utilizations, pointed out the most likely minerals to be utilized next as well as emphasized that comprehensive utilizations of nonmetallic minerals in the deposit should not be ignored. The complex deposits provide abundant mineral resources for people and cause many difficulties of recycle. In order to do comprehensive utilization of resources well, it is necessary to investigate thoroughly inherent characteristics of the ore as well as have corresponding assessment and motivation mechanism so that the comprehensive utilizations could be put into practice indeed and mineral resources could be used as far as possible.

The automobile beam steel is mainly used for such structural components as longitudinal beam, lining beam and cross beam on the chassis of heavy truck, so its comprehensive performances are vital to the driving safety and service life of the whole vehicle. The TiN inclusions with large size seriously harm the processability and usability of BT700L steel, while the amount and morphology of inclusions in steel as well as low-temperature impact and corrosion resistance of steel could be improved by rare earth. In the paper, the effects of rare earth Ce on formation of TiN inclusions in BT700L steel are studied based on the industrial tests and thermodynamic calculations. The study results showed that pure TiN inclusions and composite inclusions of Al-O+TiN were mainly formed in the BT700L steel without Ce, while pure TiN inclusions and composite inclusions of Ce-Al-O(-S-Ca)+TiN were mainly formed in the BT700L steel with Ce. The results of thermodynamic calculations showed that precipitation temperature of TiN inclusions could be decreased with the increase of Ce content in BT700L steel so that the precipitation of TiN inclusions was restrained. Such methods as reducing contents of nitrogen and titanium in steel as well as increasing solidification rate could be taken to decrease the sizes of TiN inclusions.

The inheritance mechanism of rare earth element lanthanum in baiyuneboite during process of blast furnace ironmaking is studied by taking rare earth lanthanum as the object. The microscopic behaviors of lanthanum from slags to iron during process of blast furnace ironmaking are analyzed by thermodynamic calculations and experimental characterization. The results indicated that La₂O₃ in blast furnace slags could be reduced to LaC₂ during process of blast furnace ironmaking, and then LaC₂ is dissolved in molten iron and La is adsorbed by the oxygen functional groups on porous graphite so that the rare earth could be inherited to subsequent steelmaking processes, which makes up for the problem in traditional view that the rare earth oxides in blast furnace slags are difficult to be reduced during process of blast furnace ironmaking and cannot be inherited to subsequent processes.

The effect laws of coiling temperature on microstructure and texture of 50W470 non-oriented silicon steel under hot rolling and normalizing processes are studied with such detection and analysis technologies as the optical microscope (OM) and electron back-scattered diffraction (EBSD). The results showed that high temperature coiling could promote the transformation of deformed microstructure in central layer of hot rolled plate to equiaxed grain without distortion. The promoting effect of coiling at 740 ℃ is better than that of coiling at 600 ℃. After high temperature coiling, the proportion of favorable texture {100}+{110} is increased, while the proportion of unfavorable texture{111} is decreased. After normalizing, the microstructure of high temperature coiling plate is with perfect recrystallization and the deformed microstructure is disappeared as well as the coiling plate with temperature of 740 ℃ is with more favorable texture {100}+{110} and fewer unfavorable texture{111} than those of coiling plate with temperature of 600 ℃.

In this paper, the effects of rare earth element Ce on DWTT properties of pipeline steel are studied in laboratory by taking X80 pipeline steel as the research object. The study results showed that the addition of rare earth element Ce could help to improve the low temperature toughness of test steel. The impact energy of sample after adding rare earth element Ce could reach 210 J at -40 ℃, which is increased by 19.3% compared with that of sample without adding rare earth. The addition of rare earth element Ce could help to reduce the ductile-brittle transition temperature of pipeline steel. The impact energy of heat affected zone after welding for sample without adding rare earth element is 189 J and the impact energy of heat affected zone for sample after adding rare earth element Ce could reach 216 J, which is increased by 14.3%.

In this paper, the effects of lanthanum content on inclusions in steel are studied by the induction furnace experiment and thermodynamic calculations. It was concluded that the rare earth oxysulfide was formed firstly, then aluminate, oxide, carbide and sulfide of rare earth lanthanum were formed as well as lanthanum-silicon and lanthanum-aluminum intermetallic compounds and rare earth hydride with smaller reaction trend were formed finally under the thermodynamic condition of molten steel of Q450NQR1 steel for railway carriage. It is obtained that the inclusions of LaAs and LaP could be generated during solidification process through the calculations with Ohnaka segregation model.

The applications of elements are out of balance in the rare earth industry in our country as well as abundant lanthanum and cerium are surplus so that the applications of rare earth in steel are gradually heeded. In the paper, the research progress on treating steel with rare earth lanthanum and cerium at home and abroad in recent years are overviewed, which includes the effects of rare earth on purifying liquid steel, modifying inclusions and microalloying as well as design of deoxidation test for rare earth proves the feasibility of rare earth as deoxidizer of liquid steel. Moreover, the performances of rare earth in strengthening properties of steel as well as superiorities of purifying liquid steel with rare earth and alkali metal and microalloying of rare earth under low oxygen condition are introduced. The efficient utilizations of rare earth in steel are expected based on summarizing the on-going results.

The iron and steel industry is the pillar industry in national economic development as well as its energy conservation and carbon reduction are the priority among priorities to achieve the national development goal of “carbon dioxide emission and carbon neutrality”. In this paper, it is briefly introduced the types and characteristics of main low carbon ironmaking technologies with hydrogen metallurgy as well as expounded its progress and current situations at home and abroad. The hydrogen rich reduction technology with blast furnace and hydrogen-based direct reduction technology with shaft furnace are the main technologies of low carbon ironmaking technologies with hydrogen metallurgy. Among them, the ability of carbon reduction for hydrogen rich reduction technology with blast furnace is limited, so it can be as short-term development direction of low carbon ironmaking technologies with hydrogen metallurgy for iron and steel industry. If combine with the carbon capture, utilization and storage (CCUS) technology, CO₂ emissions could be further decreased. The hydrogen-based direct reduction technology with shaft furnace is without fossil energy in production process and carbon emissions could be reduced by over 80% compared with traditional production process of “blast furnace-converter”, which is inevitable development trend of technological reform in the iron and steel industry. In order to actively respond to the national green and low carbon development strategy and five major political tasks of Inner Mongolia, Baotou Steel actively implements the green low carbon ironmaking technologies with hydrogen including hydrogen-based mineral phase transformation of medium lean ore in Bayan Obo, hydrogen rich reduction with blast furnace and hydrogen-based direct reduction with shaft furnace so that the low carbon green production process of iron and steel is significantly improved.

In the paper, the technical progress of ironmaking system of Baotou Steel is summarized and analyzed. It is thought that the technological breakthrough and innovation of beneficiation, sintering and smelting problems for special iron ore of Bayan Obo are fundamental guarantee for achieving the ironmaking production with high efficiency and quality, low consumption, long service life and environmental protection as well as technical support of great-leap-forward development for ironmaking of Baotou Steel.

The baiyuneboite is the largest paragenic ore of rare earth resource reserve in the world. It is the key of effectively utilizing rare earth resources to figure out the inheritance rules of rare earth in steel as well as clearly understand roles and mechanisms of rare earth in steel. In the paper, it is summarized the years of research achievements of authors’ team as well as inheritance of rare earth of baiyuneboite in steel, effects of rare earth on metallurgical quality of steel and microalloying of rare earth in steel. The related fundamental research work can enrich the understanding of roles of rare earth in steel as well as provide theoretical and technical supports for high-quality and efficient utilizations of rare earth resources of baiyuneboite in steel.