The effects of flow control device on flow conditions of molten steel in tundish are studied with the method of physical simulation through establishing physical model of tundish for double-strand slab caster with geometric similarity ratio of 1∶4 based on the similarity principle. The results showed that the peak time and average retention time of molten steel in tundish were increased, volume of dead zone for molten steel in tundish was reduced due to the optimized flow control device was adopted by tundish of slab. The peak time of molten steel is increased by 240.98%, average retention time of molten steel is increased by 2.37% and volume of dead zone is reduced by 7.56%. As a result, the flow conditions of molten steel in tundish are optimized as well as collision, aggregation, floatation and removal of inclusions in tundish are promoted so that the cleanliness of molten steel is ensured.

The effects of refining slag on cleanliness of liquid steel are very important. Its main functions are improving the deoxidizing capacity of deoxidizing elements, absorbing nonmetallic inclusions in steel and preventing secondary oxidation of liquid steel to generate FeO, MnO and SiO₂. In the process of refining liquid steel, the reasonable composition of refining slag plays a role of adsorbing and removing inclusions in steel. In the process of smelting rare earth steel, rare earth oxides and rare earth sulfides are formed due to rare earth is easy to react with oxygen and sulfur elements in steel as well as rare earth elements could enter refining slag because of the function of potential energy of high oxygen and sulfur for refining slag. In the production process of steelmaking, the contents of each component in ternary refining slag CaO-SiO₂-Al₂O₃ are different and the effects of rare earth on physical properties of refining slag are different because of different deoxidation systems. In the paper, such physical properties of rare earth refining slag when smelting rare earth steel as melting point, viscosity and alkalinity are analyzed by means of testing to predict the physical properties of refining slag, which could provide theoretical basis for improving the level of slag formation, cleanliness of smelting steel grade and yield of rare earth.

In this paper, the differences of microstructure, mechanical properties and resistance to hydrogen sulfide stress corrosion between as-hot-rolled steel pipe and quenched and tempered steel pipe are compared and studied. The study results showed that the microstructure of as-hot-rolled steel pipe consisted of bainite, martensite as well as a small amount of ferrite and pearlite, its tensile strength could meet the requirements of technical agreement, but elongation was close to lower limit of the requirements of technical agreement; the microstructure of quenched and tempered steel pipe was tempered sorbite, strength and toughness and ductility were significantly improved compared with those of as-hot-rolled steel pipe, impact energy at 0 ℃ was over 2.5 times of lower limit for the requirements of technical agreement as well as it is with good resistance to hydrogen sulfide stress corrosion.

In the denitrification process, flue gas needs to be heated due to the temperature requirements of denitration reaction are high, more blast furnace gas is consumed so that a large amount of CO₂ is generated. In order to achieve the energy conservation and carbon reduction, energy saving type built-in direct fired furnace is used instead of traditional heating furnace. The flue gas is heated with the heat released by igniting the CO in flue gas with energy saving type built-in direct fired furnace so that the consumption of blast furnace gas and carbon emission are reduced as well as temperature requirements of denitrification could be met. The consumption of blast furnace gas is reduced by 17.9% with energy saving type built-in direct fired furnace, annual CO₂ emission reduction of over 35 000 t is achieved and annual cost saving could reach over RMB 4 million yuan through applications and comparisons, which could meet the requirements of energy conservation and carbon reduction for steel enterprises on the premise of meeting requirements of denitrification reactions.

In the paper, it is introduced the operation systems of cloud computing platform of Baotou Steel increase continuously with the development of enterprise informatization so that the time of operation and maintenance and routing inspection is long as well as efficiency is low. The regular operation and maintenance and routing inspection of server of operation systems are realized so that their efficiency is improved, hidden troubles are found out and eliminated timely as well as stability of system operation is improved by compiling the Shell script.

The identification resolution system for industrial Internet of Baotou Steel is connected to the national top-level node upward as well as radiates constituent companies in the whole industry chain and various application systems downward to form such typical application modes as enterprise management, manufacturing, product tracing, supply chain management and life cycle management so that the effects of reducing costs, improving quality and increasing efficiency are gradually emerged. Meanwhile, it will help enterprises get through data sharing channel, realize full control of different objects and full service of different products, effectively promote prosperity and development of identification system + integrated innovative application, further promote deep integration and high-quality development of industrial Internet and real economy as well as help enterprises accelerate digital transformation and upgrading through the application researches of identification resolution system for industrial Internet in the iron and steel industry.

The characteristics of continuous cooling transformation of fire-resistant test steel are analyzed as well as its microstructure at different cooling rates within 1~100 ℃/s are observed through drawing the continuous cooling transformation(CCT) curve of 345 MPa grade fire-resistant test steel. The results showed that there were ferritic and perlitic transformations of test steel when cooling rate was 1 ℃/s; there were ferritic and bainite transformations of test steel when cooling rate was 8~20 ℃/s, pearlite completely disappeared, grain size was reduced and proportion of bainite structure was increased; microstructure transformation of test steel was mainly bainite transformation, proportion of ferritic transformation was very low and grain size was further reduced when cooling rate was 50~100 ℃/s; ferrite disappeared completely, all the microstructure was changed to bainite and was with obvious tendency of lath when cooling rate was increased to 100 ℃/s. The analysis of CCT curve and microstructure for fire-resistant test steel provides theoretical basis for formulating cooling processes in the production process of 345 MPa grade fire-resistant test steel.

In the paper, the general situations of production processes for 380HBW grade LH on line heat treated rail exported to Mexico are introduced. Its batch production is successful by microalloying component design, control of high cleanliness for smelting process as well as accurately regulating and controlling the on line heat treatment process of rail. All its performances could satisfy the technical requirements of users and requirements of AREMA standard as well as pass the SGS international testing and certification so that it could satisfy the operating requirements of freight train with great axle load on heavy haul railway abroad. It has been exported to such countries as Mexico, Australia and America.

In the paper, the detection method of magnesium content in silica-based composite material is studied and its purpose is to accurately detect magnesium content in the process of preparing silica-based composite materials so as to control the content of magnesium silicate in final product. During the experiment, the method for determining magnesium content in magnesium silicate-carbon-encapsulated silicon oxide composite material with the inductively coupled plasma atomic emission spectrometry (ICP-AES) is established. Finally, it is verified that the detection limit is 0.004 mg/L, relative standard deviation of detection results is less than 5% and linearly dependent coefficient is above 0.999 so that this method is satisfied with the test of magnesium content.

A large amount of particulate matter, sulfur dioxide and nitrogen oxide are generated in production process of iron and steel enterprises. In order to reduce further damage of these pollutants to the atmospheric environment, it is necessary to carry out desulfurization and denitrification treatments for discharged flue gas. The conventional technologies of desulfurization and denitrification are with such drawbacks as large occupied area and smaller adaptative reaction temperature interval. In the paper, a new integrated technology of desulfurization and denitrification with fixed bed is emphatically introduced, which is with such characteristics as small occupied area as well as better adjustability of desulfurization and denitrification efficiency so that it is suitable for different production environments. After the technology is applied, the integration of dust removal, desulfurization and denitrification could be achieved as well as concentrations of pollutants could all reach the ultra-low emission standard.