In this paper, the dissolution methods of iron ore and slags are studied. The decomposition method of preliminarily dissolving with hydrochloric acid followed by treating the residue with mixed flux of sodium carbonate-boric acid is applied. The analytical spectral lines with high sensitivity and fewer interferences are determined as analytical spectral lines through optimizing and selecting the analytical spectral lines of lanthanum, cerium, praseodymium, neodymium and samarium by experiments. Moreover, the contents of such five elements as lanthanum, cerium, praseodymium, neodymium and samarium are determined simultaneously with ICP-AES. The results showed that the lower detection limit of lanthanum, cerium, praseodymium, neodymium and samarium in iron ore and slags was 0.005 0%, the upper detection limits of rare earth elements in iron ore were 5% for La, 10% for Ce, 1% for Pr, 2% for Nd and 1% for Sm as well as all the upper detection limits of rare earth elements in slags were 0.500%.

In this article, the current conditions and development tendency of cooling bed in the production line of section steel are introduced. A new type of captation and dewatering installation for spray cooling system is designed to solve the problems in applications of spray cooling technology in production of cooling bed. Its layout and structure are mainly introduced combining with design drawings. It is with such characteristics as lower costs, shorter construction period, easier installation and convenient maintenance. With these characteristics, the advantages of spray cooling technology for temperature control in cooling process of section steel could be fully taken, the cooling effect of cooling bed on limited area is better and capacity of cooling bed is improved with the spray cooling technology, which provide reference for upgrading the spray cooling system of online cooling bed.

In this paper, the sintering productions with such SiO₂ contents in sinter as 4.75%, 4.85%, 4.95%, 5.15% and 5.30% are carried out based on the effects of different SiO₂ contents on sinter with 500 m² sintering machine. The results showed that the drum strength of sinter was increased with gradual increase of SiO₂ content in sinter when SiO₂ content in sinter was less than 5.15%; the drum strength of sinter was optimum when SiO₂ content in sinter was about 5.15%, which was increased by 3% compared with that of 4.75% and average particle size was increased by 1.77 mm; the drum strength changed slightly with continuous increase of SiO₂ content when SiO₂ content in sinter was increased from 5.15% to above 5.30%. The analysis on the microstructure of sinter with different SiO₂ contents showed that the prismatic tabular calcium ferrite was increased with the increase of SiO₂ content and the dicalcium silicate of partial region was with large area enrichment. With the high proportion of self-produced concentrate of Baotou Steel, the SiO₂ content is controlled at about 5.15%, drum strength of sinter can reach above 79.5% and average particle size can be improved above 19 mm.

In the paper, it is proposed how to select the pipeline material and some matters needing attention in low temperature environment condition by analyzing the lowest design operating temperature of gas pressure piping in the iron and steel industry. The gas pipe in the iron and steel industry is usually with large pipe diameter and low pressure, so it is not pressure piping. With the development of new technologies, some gas pipes with pressure higher than 0.1 MPa are pressure piping. The design of material should be based on the pressure piping code. In the severe cold area, when the lowest design operating temperature of pipe is lower than -20 ℃, the applicability of materials selected for pressure piping in low temperature conditions shall be considered.

The mineral species that have been found in Bayan Obo ore deposit are sorted and recorded based on the list of mineral species in Bayan Obo mining area in Mining and Metallurgical Technology of Baiyuneboite as well as the research achievements of minerals of Bayan Obo are collected combining with such documents as Mineralogy of Bayan Obo. The results showed that there were 172 types of minerals in the list of mineral species in Mining and Metallurgical Technology of Baiyuneboite after correct obvious errors, the minerals reached 191 types by supplementing the minerals that were not recorded in Mineralogy of Bayan Obo; a total of 209 types of minerals have been found in Bayan Obo ore deposit so far, together with the newly found minerals and new minerals.

In order to solve such problems as low efficiency, long time-consuming, large human input and potential safety hazards for the overall replacement of conveying belt in processing line as well as complete the overall replacement of conveying belt safely and efficiently, a set of equipment for automatically changing conveying belt is studied and designed through theoretical analysis and calculations combining with practical experiences. The equipment includes the drive system of old belt, support system of new belt and control system. After the old belt is disconnected, one end is fixed onto drive unit as well as drive system is started to export and roll up old belt, while the old belt is to import new belt. After that, vulcanize and bond the new belt. The practices prove that the automatic replacement of belt could be realized with the equipment as well as the whole process is safe and efficient, which is with wide application prospect.

Four new types of coal are increased through developing independently and introducing the new types of coal in Shanxi and Inner Mongolia as well as utilizing the SXLLSJM、SXJM and HDSJM, part of which is instead of such types of coal with tension supply as ZYDM and LLGHM. As a result, the scope of coal used for rammed-coal coking is expanded, tension trend of using coal is relieved, the existing coal blending structure of rammed-coal coking is optimized and coke quality is improved. The ash content of coke is reduced and the hot strength of coke is increased, which provide the strong fuel support for the stable and trouble-free operation of blast furnaces of Baotou Steel.

In the paper, the recrystallization annealing process is studied by taking Fe-Mn-Al-C high manganese austenitic steel as object of study. The thermal simulation tests with series of temperatures, hardness test and metallographic analysis are carried out to the test steel. The study results showed that the recrystallization temperature was 750 ℃ when annealing holding time was 120 s and recrystallization temperature was increased to 800 ℃ when annealing holding time was shortened to 60 s. The grains remain uniform and fine as well as hardness value of test steel is with a little change when the holding time is 120 s at 750~900 ℃.

It is considered that there is no direct relation among the bubble coke rate for large capacity coke oven and the strength, ash content as well as scurf resistance M₁₀ of coke after reaction while there is certain correlation between it and coking time through their data analysis. As a result, it could not be as the evaluation index for coke quality.

In the paper, it is introduced the detection analysis on non-metallic inclusions in rail head. In order to scientifically characterize the quantity, size and distribution of inclusions, the new method for detecting inclusions is explored. A new vertical detection surface is added by taking the sample position with the K method for cleanliness of oxide in the EN 10247—2017 standard, that is, such two sampling methods as vertical plane and inclined plane are adopted separately. The quantity, size and distribution of inclusions in rail head are statistically analyzed with fully automatic optical microscope as well as the compositions of typical inclusions are analyzed with scanning electron microscope and energy disperse spectroscopy. The distribution and sources of inclusions in the rails of Baotou Steel are comprehensively analyzed, which provide technical support for further improving and controlling the cleanliness of rail steel.