The effects of the scratch defect at rail bottom on fatigue life of rail are studied by MTS100T fatigue testing machine. The results showed that the ability of bearing load for rail was declined and its fatigue life was shortened with the transverse scratch defect at rail bottom. The depth of scratch defect at rail bottom obviously influences the fatigue life of rail. With the scratch defect at rail bottom of 75 mm long, if its depth is 0.3 mm, the fatigue life decreases by 27.2% on average, while if its depth is 0.5 mm, the fatigue life decreases by 31.4% on average.

The distribution law of apatite mineral in a tailing of Inner Mongolia is 9.25% and content of P₂O₅ is only 3.73% so that it is low-grade phosphorus mineral. Based on the condition experiment, the open circuit test of primary rougher flotation and secondary concentration is carried out with sodium carbonate as the pH adjusting agent, water glass and HSL as the depressor as well as modified fatty acid TQHY as the collecting agent aiming at the difficult problems of low grade of apatite, many types of gangue mineral containing calcium and similar floatability. Finally, the phosphate concentrate with the grade of P₂O₅ of 33.02% and recovery rate of 78.67% is obtained as well as good separating indexes are obtained.

In this paper, the improvement is from the point of view of deformation process by increasing the number of roll in finished pass to form four-roll finished pass, increasing the constraint in direction of depth of rail and limiting free spread of rail surface so as to improve dimensional accuracy of depth of rail aiming at the existing problems in universal rolling of rail. The numerical calculation is performed using ANSYS/LS-dyna, deformation states in different conditions are analyzed, defects are amended so that the optimal solution is obtained. The better effects are obtained by applying it in production line of rail, fluctuation range of depth within the full length range of rail is reduced and defect of “high zone” caused by local depth fluctuation is solved so that the safety of running for high-speed train is improved.

In the paper, the continuous cooling transformation (CCT) curve of test steel is determined with FORMASTOR-F full automatic phase transformation instrument by taking 38CrMoAl steel as the research object. The results showed that the microstructure at room temperature was proeutectoid ferrite+pearlite when cooling rate was 0.2~ 0.5 ℃/s; the microstructure at room temperature was ferrite+pearlite+bainite and there was a small amount of bainite when cooling rate was 0.5~1 ℃/s; the bainite was formed at the temperature near Bs in the uppermost part of transition zone for bainite and the microstructure at room temperature was upper bainite when cooling rate was 1 ℃/s; the martensite increased continuously and bainite decreased gradually as well as the microstructure at room temperature was mixed microstructure of bainite+martensite when cooling rate was 2~5 ℃/s; the microstructure at room temperature was just martensite when cooling rate was not less than 5 ℃/s, which provide the reference basis for formulating heat treatment process.

In order to improve the grade of iron concentrate and reduce the contents of other gangue minerals in iron concentrate, the concentration with wash mill is added after finely sieving in Concentration Plant of Baotou Steel. Moreover, such tests as feeding concentration of wash mill, magnetic field intensity, opening of water valve and bottom valve are carried out. Finally, the grade of iron concentrate increases from 56.8% to 67.0%, recovery rate of iron is 93.42% so that the effects of quality improvement and impurity reduction are achieved.

In the production process of 2 250 mm hot continuous rolling band steel, there would be a large number of warp defects at edge of low carbon steel. In order to reduce or avoid the occurrence of warp defect, its causes are analyzed from its morphology, the relation between generation of warp and edging draught of vertical roll of roughing mill, time in furnace and tapping temperature of slab as well as control of Mn/S for composition of slab. Finally, the corresponding countermeasures are formulated so that the occurrence rate of warp defect is reduced.

As the important energy medium, gas is widely used in each working procedure of metallurgical enterprises, but the inaccurate measurement of mixed gas flow always troubles accurate measurement of enterprise energy. In the paper, it is introduced the composition and general situations of mixed technology for gas of Baotou Steel, elaborated the measurement principle of throttling differential pressure flow meter, analyzed the causes of errors with differential pressure flow meter in the detecting system of mixed gas flow as well as proposed the method for correcting measurement of mixed gas flow under different working and equipment conditions so that the problem of inaccurate measurement of mixed gas is solved.

In the paper, the particle size distribution of blended coal is optimized according to the quality indexes of blended coal with different granularity compositions through analyzing properties of blended coal for tamping coking of Baotou Steel with different particle sizes so that standard deviation of granularity composition for blended coal gradually reduces. In addition, the selective comminution of hard coal is carried out through selective precomminution technology so that the quality of blended coal is stabilized. On the premise of ensuring stability of coal cake, 1/3 proportion of coking coal and gas coal is improved so that the consumption of high-quality coking coal and cost of blending coal reduce.

The Yangliugebu Iron Ore occurs in the amphibolite gneiss of Eastern pentamolecular formation of Seltengshan (rock) group in Neoarchean and the ore body is composed of magnetite quartzite. The amphibolite gneiss and magnetic anomaly are direct indicators for deposit. The iron ore in this area is with stronger magnetic properties, so it can be as an indirect indicator for deposit.

The strength of 440 MPa grade phosphorous high-strength IF steel independently developed by Baotou Steel is improved by adding such alloying elements as Si, Mn and P based on ultra low carbon steel. The control requirements of its composition and production process are strict as well as production is very difficult. In the paper, the influences of chemical elements on stamping performance of 440 MPa grade high-strength IF steel are mainly studied. The microstructure of steel strip, inclusion morphology and precipitation behavior of the second phase particles are analyzed with metalloscope and scanning electron microscope. The mechanisms of action of hot rolling processes such as finishing and coiling temperatures, continuous annealing process of cold rolling on microstructure and mechanical properties are explained. The mechanical performances of tested steel strip are stable and could meet the relative technical requirements through formulating reasonable process route and strict control.