In this article, the stability of old underground space in Sanheming Iron Mine is analyzed with the FLAC^3D numerical simulation software as well as distribution laws of stress, displacement and plastic zone of old space with effects of self weight stress field are studied. It is aimed at judging whether old space is stable to analyze the stability of old space with effects of its self weight stress field in order to provide effective preventive measures for managing old space of mine as well as ensure safe and efficient mining of mineral resources. The stability of old space with effects of self weight stress field is considered to be good through 3D modeling and numerical calculations. The study results can provide references for stability analysis of underground goaf in similar iron mines, which is with certain guiding role in ensuring safe production and reducing geological disaster risks as well as significances to promote sustainable development of mineral resources of Sanheming Iron Mine.

In the paper, it is introduced the Charpy pendulum impact test and drop weight tear test (DWTT) of L360M pipeline steel coil plate with the thickness specification of 11.00 mm. The test results showed that the differences of toughness at relevant positions of the same plate are smaller. It can be seen from the macroscopic morphology of fracture of samples for DWTT that the bigger the deflection of samples, the more obvious the distortion of samples for fracture after hammering to breakage, even some samples could not be hammered to breakage completely because of warping.

In this article, the low temperature performances of 60 kg/m as-hot-rolled U71Mn and U75V rails as well as U71MnH and U75VH rails after on-line heat treatment produced by Baotou Steel are studied. The relation between the toughness and temperature of different rails in low temperature environment is studied through impact test and test for fracture toughness of rails in the low temperature environment created in the laboratory. It is elaborated the performance indexes of safe service for rails of Baotou Steel in low temperature environment and summarized the relations of toughness indexes for four types of rail products of Baotou Steel in low temperature environment, which provide the data support for selecting rails in plateau and low temperature regions as well as safe operations of railway system in extremely cold environment.

The status survey and heat loss test of steam pipeline network system of Baotou Steel are carried out as well as its amount and rate of heat loss during heating season in the winter are calculated aiming at its existing problem of great heat loss. The energy saving transformation measures to reduce heat loss of steam pipeline network system are put forward by analyzing current influencing factors of greater heat loss for the system, which could provide the reference for transforming steam pipeline network system of Baotou Steel.

In this paper, the research is carried out from such aspects as chemical composition, size composition, basic sintering characteristics and process parameters adjustment after production applications of Mongolian powder ore. The research results showed that the air permeability of sinter bed became worse, utilization coefficient was decreased by 0.001 t/ (m²·h), solid fuel consumption was increased by 0.83 kg/t, drum strength was decreased by 0.63 percentage point, average particle size was decreased by 0.05 mm, proportion of particle size of 5~10 mm in finished sinter was decreased by 0.12 percentage point and direct material cost was decreased by CNY 8.15 Yuan/ t when 7% Mongolian powder ore was used to replace the same proportion of Mac powder ore. The sintering process could maintain stable state by increasing moisture of mixture by 0.1 percentage point and fuel proportion by 0.2 percentage point.

In the energy consumption of sintering process, solid fuel (powdered coke and anthracite) consumption accounts for 70%~80%, so it is the key to reduce solid fuel consumption for reducing energy consumption of sintering process. In the paper, it is introduced the air leakage rate of sintering machine is decreased to 35% and effective height of sinter bed is increased to 780 mm through such measures as equipment transformation, optimizing technological operations and strengthening production management combining with the existing conditions of raw materials and fuels aiming at the problem of higher solid fuel consumption for 265 m² sintering machine of Baotou Steel; proportion of size fraction of outsourced powdered coke <1 mm for sintering is decreased from 41.02% to 22.72% through revising the purchase standard of outsourced fuels for sintering so that size composition of fuel for sintering is improved. The solid fuel consumption for 265 m² sintering machine of Baotou Steel was reduced to 50.75 kg/t in 2023 through the above measures, which was 1.70 kg/t lower than that in 2021.

The packaging capability of Φ159 mm PQF hot continuous rolling steel pipe unit of Baotou Steel is unmatched with previous process due to its inadequate design and new packaging standard of steel tube is implemented. As a result, the steel tubes are piled up before packaging process so that the whole production line is restricted to reach target output and efficiency. In the paper, the causes restricting packaging capability are found through causal chain analysis and functional modeling with the theory of inventive problem solving (TRIZ). Such equipment as packer and storage rack of steel belt are designed and manufactured so that the bottleneck of packaging process capability is broken through and capacity balance between processes of the whole production line is realized. The yield and packaging quality of seamless tube are greatly improved through the successful reconstruction of packaging system.

The basicity is an important chemical index of blast furnace slag and it plays a decisive role in the trouble-free operations of blast furnace ironmaking. In this paper, the effects of basicity on rheological behavior of blast furnace slag of Baotou Steel are studied under N₂ atmosphere with slag specimen prepared by pure chemical reagent based on the slag of 4^# blast furnace of Baotou Steel. Moreover, the rules of melting behavior for blast furnace slag with basicity of slag changes are analyzed. The results showed that the melting temperature, viscosity and activation energy of viscous fluid flow of blast furnace slag of Baotou Steel were first decreased and then increased as well as fluidity and thermal stability of slag became better first and then worse when basicity of slag was increased from 1.00 to 1.30. With the basicity of slag increases, the softening temperature, hemispherical temperature and flow temperature of blast furnace slag tend to be increased, which are conducive to moving down of softening zone of blast furnace in the process of ironmaking and promoting development of indirect reduction in blast furnace. It is suggested that the basicity of blast furnace slag of Baotou Steel should be controlled within the range of 1.10~1.20 through overall consideration of the effect laws of basicity of slag on viscous and melting behaviors of blast furnace slag of Baotou Steel.

The rail head of 43 kg/m rail with material of U71Mn after induction hardening by user is cracked during straightening process. The rail is inspected with such methods as the chemical analysis, fractography, metallography detection and scanning electron microscope analysis. The results showed that the chemical composition could meet standard requirements, fracture morphology of fracture origin and microstructure were abnormal, melting holes and oxidation characteristics at grain boundary could be seen locally. The offline quenching induction heating process is judged to be abnormal. Different degrees of overburning and overheating are formed in near surface area at round corner on one side of rail, i.e. oxidation and melting at grain boundary. The abnormal microstructure of coarse cementite+ledeburite is formed after quenching so that the rail is cracked in subsequent straightening process.

In the paper, the alloying component system of BTP600 armor plate is designed as well as the laboratory researches on steelmaking, hot rolling and heat treatment are carried out with pilot platform. The results showed that the component system with C content of 0.42% as well as such elements as Cr, Ni, Mo and B could ensure the hardenability of BTP600 steel plate and match of impact toughness and hardness. The microstructure of as-hot-rolled steel plate is lath martensite. After tempering at 180 ℃ and 220 ℃, its boundary becomes blurry and the lath degenerates so that its length becomes shorter. With the increase of tempering temperature, the lath of tempered martensite is widened. Finally, the heat treatment process of 870 ℃ quenching+180 ℃ tempering is selected to be optimal for BTP600 armor plate, with which the impact energy at -40 ℃ could reach 15.2 J and hardness(HBW) is 624 for BTP600 steel plate.