According to the smelting process of converter, the heat balance of converter is calculated with the heat balance calculation method. The influences of different molten iron conditions, production processes and temperature control on improving the addition of scrap steel are calculated. The specific measures for improving the scrap ratio of basic oxygen furnace(BOF) are put forward by analyzing the factors affecting change of scrap ratio of BOF as well as studying the relations between scrap ratio and smelting process conditions of BOF, which are as references for relevant steelmaking plants.

The zinc and copper are separated from lead and tin based on the characteristics that ammonium hydroxide, zinc and copper form complex ions as well as ammonium hydroxide, lead and tin form precipitates. The effects of the acidity of zinc, lead and tin titrated with ethylene diamine tetraacetic acid (EDTA), added quantity of thiourea and ammonium fluoride as well as buffer solution on determination are tested. The test results showed that the pH value of solution acidity was 4.5~5.0 and selectivity of titration was higher when zinc was titrated with EDTA; pH value of solution acidity was 5.0~6.0 when determined lead and tin as well as the colors at titration end point changed sharply. The interference of coexisting ions could be avoided by adding sulfosalicylic acid. The determination range of this method is 0.50%~20%, relative standard deviations of zinc, lead and tin in tin bronze samples are all smaller than 2.0% through analysis as well as adding standard recovery is 97%~103%.

The super large deposit of Nb, rare earth and iron in Bayan Obo is currently one of the mines with the most varieties of new minerals discovered in the world. The dolomite type ore with Nb and rare earth is the most widely distributed ore type in this area as well as it is with significant meanings to research its characteristics such as mineralogy. The dolomite type ore in East Mine of Bayan Obo is collected through field work as well as the petrographic identification and process mineralogy analysis are carried out. The results showed that the dolomite was distributed in subidiomorphic-xenomorphic granular form among fluorite, its particle size was uniform and generally 0.1~0.3 mm; the magnetite was mostly disseminated in subidiomorphic aggregation among fluorite and dolomite and its particle size was generally 0.3~1.0 mm. The main oxides of ore are CaO and MgO as well as the content of dolomite in this type of ore could reach 70%.

The coiler in production line of hot continuous rolled strip steel is the only equipment for coiling strip steel after rolling and its stability of working condition directly affects the stable production of production line, yield and appearance quality of coil of strip. The level of stiffness of wrapper roller for coiler is the core factor determining stability of coiler. In the paper, the concept of stiffness of wrapper roller for coiler in production line of hot continuous rolled strip steel as well as the significances and methods of static test are elaborated. The analysis sheet of stiffness of wrapper roller is obtained through tests as well as collecting, analyzing, summarizing and calculating related data. Guide the craft personnel to set and optimize parameters as well as equipment personnel to eliminate defects purposefully to ensure stable operation of coiler, reduce coiling accidents and improve yield as well as ensure coil shape and appearance quality of strip steel.

The hot bends are important components of oil and gas transmission pipeline, so the research and development of hot rolled band for L415M hot bends are with important significances. The band is with low carbon and microalloyed composition of Nb-Ti-Mo, high cleanliness smelting as well as reasonable controlled rolling and controlled cooling process, so it is with excellent comprehensive properties, its microstructure is fine and uniform ferrite and pearlite and their grain size is grade 12.0 as well as the inclusion control is good. Its dimensional accuracy is high as well as surface quality and strip shape are good. After the band is manufactured to hot bends, their overall performances are excellent so that they could meet the operating requirements of users. As a result, the bulk sales and successful applications are realized as well as product quality is well appraised by users.

The requirements of non-chrome passivation film for galvanized home appliance plate are mainly focused on such aspects as corrosion resistance, stamping and powder injection performance. In this paper, it is mainly introduced the influences of film weight on the corrosion resistance of non-chrome passivation steel plate, influences of powder injection process parameters on adhesion of powder as well as dynamic friction coefficients of non-chrome passivation products with different compositions and their main applications. In order to achieve good effects, strict control is required in the process of industrial production and end use.

The large-grained ribbed Al₂O₃ inclusion is the main cause of cracking through analyzing the cracking in process of stamping beam steel BT700L. In order to improve the size and morphology of inclusion in product, the rare earth Ce is added in production of beam steel BT700L. Since the affinity of rare earth Ce and oxygen is very strong, the rare earth Ce in molten steel reacts with oxygen and generates rare earth oxide (RE₂O₃) coming up to slag so that the yield of rare earth Ce in steel is extremely low. It could be improved effectively through optimizing and controlling the content of Ce in molten steel of steelmaking and continuous casting, oxidability of slag as well as such process as protective casting of continuous caster. Moreover, the atomic radius of rare earth Ce is greater than that of iron atom and rare earth Ce could denature inclusions in steel. It is found that the size of inclusion in product becomes small, morphology of inclusion spheroidizes and low temperature impacting property of product is effectively improved after add rare earth Ce into molten steel through studying and analyzing adding rare earth Ce into beam steel BT700L.

The 800 MPa grade hydropower engineering steel with low welding crack sensibility is developed through smelting test steel with 100 kg vacuum induction furnace as well as thermal mechanical control processing (TMCP), quenching and tempering processes adopting the alloy system route of low carbon, carbon equivalent (Ceq) and welding crack sensibility index (Pcm) in laboratory. Such mechanical properties as the strength, impact and bending of test steel are tested as well as its microstructure and fracture morphology are analyzed with the optical microscope (OM) and field emission scanning electron microscope (SEM). The results showed that its microstructure at room temperature was tempered sorbite, all its mechanical properties were excellent, its yield strength, tensile strength and elongation after fracture were 788 MPa, 842 MPa and 18.1%, low temperature impact absorbing energy at -40 ℃ was 197 J, strength and toughness well matched as well as welding crack sensitivity index was low, which could meet the performance requirements in use.

The gas flow distribution and gas utilization rate are improved by optimizing the charging system as well as adjusting the material layer thickness of coke and ore aiming at the long-term higher fuel ratio of 5^# blast furnace of Baotou Steel; the smelting is strengthened by such measures as increasing furnace top pressure, hot air temperature and oxygen enrichment rate; meanwhile, the efficiency of tapping iron in front of furnace is improved, daily operations of blast furnace are strengthened and standard work is carried out so that the target of increasing production and reducing consumption is realized. The fuel ratio of 5^# blast furnace reduced from 598.73 kg/t on average in 2020 to 556.9 kg/t, which was the best level in history.

The design of power supply system in workshop needs to consider such factors as the reliable power supply, economic rationality, advanced technology and future development. In this paper, such aspects as the design principles and thoughts of high and low voltage power supply systems in steelmaking workshop of a converter project are discussed. The high voltage power supply system is elaborated mainly from such aspects as power distribution system and relay protection as well as the low voltage power supply system is elaborated mainly from such aspects as the system partitioning, power distribution system, safe power supply and security measures.