In the paper, it is introduced the categories of steel for steel structure and steel structure products, standards of steel for steel structure and development status of domestic steel structure production; the development trends of steel structure and steel for steel structure are analyzed as well as how steel manufacturing enterprises can meet the requirements of steel consuming enterprises in processes, products, standards and extended industries to promote the development of steel and industry for steel structures.

In the paper, the SWRH82B wire rod fractured in the process of drawing and twisting line is inspected with such methods as the metallographic structure examination and scanning electron microscope. As a result, the main cause for fracture is the martensite and inclusions in the center. Moreover, the unreasonable production and processing technologies are important causes for the poorer quality of wire rods. The quality of wire rod is significantly improved and the fracture in drawing is reduced by improving the production and processing technologies.

The hydrogen induced cracking (HIC) resistance of X65M pipeline steel products used in the special environment with high H₂S content is analyzed and researched. The control level of w [S] <0.002%, w [P] <0.010%, w [H] <2.0 × 10^-6 and the content of all inclusions in steel less than 1.0 is reached through the mechanism analysis on effects of chemical composition, elemental segregation and nonmetallic inclusions on hydrogen induced cracking, guiding the smelting process and the key process control of S, P, H and oxide inclusions as well as the strict protective casting measures in the continuous casting process. The inspection of hydrogen induced cracking resistance for X65M pipeline steel meets the requirements of product development standards.

Based on the LT gas recovery system with dry process of No. 2 Steelmaking Workshop in CSP Plant of Baotou Steel and combined with the actual production process and equipment operation condition, the main factors affecting the converter gas recovery amount are analyzed. The recovery level of converter gas is improved by eliminating the equipment effects and adjusting process parameters.

In the paper, it is introduced the cost of molten iron is significantly reduced with such measures as adjusting the ore blending scheme, strengthening the management level of blast furnace, improving the operation rate of key equipment and strengthening energy management of 4 150 m³ blast furnace in Baotou Steel based on actively responding to the development strategy of "reducing costs in procedures before iron making and increasing benefits in procedures after iron making".

The paper proposes a method for solving multi-destination transportation route planning problems, and tries to use the structural conditions of Hamiltonian graph/semi-Hamiltonian graph to select appropriate path to construct Hamiltonian path based on the weights of freight and time for different sections of highway so as to select the appropriate path in the transportation process for traversing all destinations without repeating and achieve the most economical transportation effect.

The mineral composition of a magnetic iron ore is complex. In order to make full use of its mineral resources, its process mineralogy was studied and the experimental study of beneficiation process was carried out. The results showed that the ore was with the characteristics of high calcium and magnesium, low silica and aluminum, which belonged to the alkaline ore; the main component of the ore that can be recovered for beneficiation was iron. Through the stage grinding and stage separation－medium intensity magnetic separation recovery process, the iron ore concentrate with the yield of 34.01%, grade of 65.36% and recovery rate of 72.50% can be obtained; through the stage grinding and stage separation-strong magnetic separation recovery process, the iron ore concentrate with the yield of 38.93%, grade of 59.62% and recovery rate of 75.69% can be obtained.

A large number of tailings after beneficiating iron of magnetite are produced every year in Concentration Plant of Baotou Steel. The content of useful minerals such as sulphur and iron in them is higher. The monomer separation is achieved by ore grinding, the sulfur concentrate with the grade of 43.39% and recovery rate of 41.54% as well as the iron ore concentrate with the grade of 63.93% and recovery rate of 8.93% are obtained with the magnetic separation-flotation process. As a result, the pressure of discharging tailings is reduced and the economic and social benefits are great.

In the paper, the orthogonal test was used to investigate the effects of reaction temperature, reaction time and material layer thickness on tailings after beneficiation of rare earth in Bayan Obo with carbon thermal reduction. The results showed that the coke powder with high volatile content was beneficial to obtain the reduced tailings after beneficiation of rare earth with high metallization ratio. The main factors affecting the metallization ratio of the reduced tailings after beneficiation of rare earth were reaction temperature, reaction time and material layer thickness in turn. The optimum test conditions were that the coke powder with volatile content of 12.6% and particle size of 0~2 mm was used as reductant, the reaction temperature was 1 000 ℃, the reaction time was 4.5 h and the material layer thickness was 10 mm.

In the paper, the effects of mold electromagnetic stirring, dynamic secondary cooling water distribution and dynamic soft reduction on the central carbon segregation index, porosity and solidification structure of ingot blank are analyzed by comparing the internal and external quality for ingot blank of heavy rail steel with bloom section produced by 7^#continuous caster after transformation. As a result, the internal quality for ingot blank of heavy rail steel with two bloom sections produced by 7^# continuous caster is fine with reasonable casting speed matched with degree of superheat and the technology of mold electromagnetic stirring + soft reduction. The equiaxed crystal ratio of ingot blank is 52.3%~58.3% and its central carbon segregation index can be controlled below 1.07.