In this article, the increase of ore types blended under the current condition of proportion of iron concentrate in sintering of Baotou Steel is researched as well as optimal ore blending scheme is proposed through comprehensive evaluation of sinter from such aspects as the chemical composition, size composition and metallurgical performances. The research results showed that the quality indexes of sinter in scheme 4 (45% self-produce iron concentrate+31% Mac fines+11%FMG mixed ore fines+5% high-silicon Brazilian rough ore fines+4% Indian ore fines+3% limonite) reached optimal values, solid fuel consumption was decreased by 3.46 kg/t compared with that of benchmark scheme, finished product rate was increased by 3.09 percentage point, drum strength was increased by 2.54 percentage point and average particle size was increased by 0.37 mm so that this scheme was preferred.

In the paper, the study on effect laws of ore proportioning structure on quality of pellet is carried out aiming at such problems as low strength and high reduction swelling rate of manufactured pellet caused by high contents of such harmful elements as K, Na, F and S in iron ore concentrate of Bayan Obo. The study results showed that the pellet could be promoted to be fully oxidized, compressive strength of pellet could be improved and reduction swelling of pellet could be restrained by adding high silicon hematite and high magnesium magnetite with low contents of sulfur and alkali metal. The compressive strength of pellet could be significantly increased to 2 380 N and reduction swelling rate could be reduced to 13.2% with the scheme of optimizing ore proportioning that 52% iron ore concentrate of Bayan Obo+32% high silicon and low sulfur magnetite concentrate+8% high silicon hematite concentrate+8% high silicon high magnesium magnetite concentrate, which could provide the theoretical support and technical path for preparing high quality pellet with iron ore concentrate of Bayan Obo.

In the design of blast furnaces in Baotou Steel, “long campaign of blast furnace” is always the subject. In order to adapt to the smelting of special ore in Bayan Obo, blast furnace profile is gradually developed towards low shaft, the part below middle of blast furnace shaft is constructed with microporous alumina carbon brick instead of carbon brick, thick furnace lining is gradually changed to thin skinned lining, furnace hearth is with domestic large carbon brick and high heat-conducting UCAR carbon brick as well as low heat-conducting furnace hearth is changed to high heat-conducting furnace hearth. The production technology management system that could ensure stable and smooth operations of blast furnace, high output and low consumption as well as campaign of blast furnace to be over 15 years is formulated through paying attention to construction quality, optimizing cooling equipment and medium parameters, adhering to the principle of beneficiated burden material, controlling contents of harmful elements as fired, keeping furnace hearth active as well as strengthening technologies and management measures at later stage of campaign.

The structural steel is widely used in such industries as automobile, construction and photovoltaics due to its good comprehensive properties. In this paper, the effects of different microalloyed compositions and metallurgical process routes on microstructure and properties of 350 MPa grade products are studied and determined based on the differences of CSP (compact strip production) and conventional hot continuous rolling aiming at the request for utilization of photovoltaic products while considering effective productions of production line. The study results indicated that the properties of products manufactured with different process routes could all meet standard requirements. Although the contents of strengthening elements (carbon, manganese and titanium) in products with CSP production line are lower than those in products with conventional hot continuous rolling production line, the yield strengths of products manufactured with the two production lines are approximate, which are 400~460 MPa.

In this paper, the effects of optimizing structure of coal as fired on metallurgical performances of coke are systematically studied by adding XN fat coal and SX coking coal S1.3 based on the coal as fired of coke oven in a company aiming at the strict requirements of coke quality for blast furnace ironmaking. The experimental results showed that the coke strength after reaction (CSR) and mechanical strength (M₄₀) could be significantly improved with both scheme 1 and 2, thereinto, CSR was increased by 7.7 percentage point, M₄₀ was increased by 6.4 percentage point as well as proportion of large and medium coke size was increased by 7.64 percentage point with scheme 2 compared with those of basic scheme. This study provides theoretical and practical basis for industrial coal blending optimization.

In order to effectively break through the bottleneck problem of capacity of sinter, upgrading and transformation of existing 265 m² sintering machine are implemented. The capacity of sintering machine is significantly enhanced through adopting a series of measures including widening trolley, upgrading main exhauster and optimizing pelletizing system. After the transformation, average daily output of sinter is increased by 1 013 t and utilization coefficient of sintering machine is improved from 1.332 t/ (m²·h) to 1.484 t/ (m²·h); drum index of sinter is increased by 0.3 percentage point and its size composition is improved; solid fuel consumption of sintering is decreased by 1.19 kg/t and electricity consumption is decreased by 4.97 kWh/t so that the energy medium and manufacturing costs are significantly reduced.

The alloying before VD (vacuum degassing) process is developed by optimizing slag formation process and deoxidation system of LF (ladle furnace) as well as the alloying operation after VD is changed to before VD process aiming at such problems as fluctuation of composition of molten steel, excessive inclusions and long production time caused by lagged alloying operation after VD in the vacuum treatment process of aluminium killed steel. The application practices showed that the holding time of white slag was extended to 15~20 min, total oxygen content of molten steel after VD was reduced to 0.001 2%~0.002 0%, rating of fine B class inclusion (Al₂O₃) was decreased from grade 2.0 to grade 1.0 and power consumption of refining was reduced to 48.51 kWh/t.

The experimental study on discarding tailings in advance is carried out for raw ore to be ground and ore discharged by primary ball mill of a mine with the processes of dry-type and wet-type discarding tailings in advance based on studying process mineralogy of low grade iron ore in the mine as well as size composition of raw ore to be ground and ore discharged by primary ball mill in the existing process. The experiment results showed that the tailings with productivity of 28.27% and content of magnetic iron of 0.44% could be discarded for raw ore to be ground with dry-type discarding tailings in advance; the tailings with productivity of 33.44% and content of magnetic iron of 0.49% could be discarded for raw ore to be ground with wet-type discarding tailings in advance; the tailings with productivity of 41.39% and content of magnetic iron of 0.36% could be discarded for ore discharged by primary ball mill with wet-type discarding tailings in advance.