The analysis of chemical components for galvanized plate matrix as well as detection of plating thickness and weight could be completed simultaneously with the glow discharge optical emission spectrometry. The optimal determination conditions are selected and lower limits of determination for each analytical element are determined by comparing and analyzing the results with different electrode sizes, discharge conditions, measured pressure and power; the analytical method for determining matrix composition, plating thickness and weight of galvanized plate is established through comparison of analytical methods as well as precision and accuracy tests.

In the paper, the dimension parameters of sizing mill and its corresponding hot tool, sizing mill stand are optimized and designed with the software, ultimate machining dimension of sizing mill stand is calculated as well as pass design of rolling specifications within ultimate dimension and theoretical analysis on optimization of rolling parameter are carried out with the numerical simulation technology and existing equipment status. The ultimate specifications of replacing stretch reducing mill with sizing mill are obtained by comparing relevant parameter design of stretch reducing mill for rolling with the same specification as well as comprehensively analyzing the status of host of equipment and production efficiency, which could provide reliable theoretical support for promoting replacing stretch reducing mill with sizing mill for rolling.

Inner Mongolia Baotou Steel Pipe Co., Ltd. owns the world's advanced production unit of seamless steel pipe as well as the main products are various hot rolled seamless steel pipes and piercing plug, the hot tool matched with piercing process of several hot rolling production lines are manufactured by the company itself. The causal chain analysis is carried out aiming at the existing problem of low yield for casting piercing plug. The process of casting system for piercing plug is optimized through taking such scheme as increasing the porous sand core of riser manufactured by exothermic materials, installing weighing device and injection of nitrogen at the bottom of moulding flask so that the above technical problem is solved.

The timely pipeline dredging for long distance slurry pipeline could effectively ensure the safe operations of high pressure pipeline system. For the long distance high pressure slurry pipeline with the inner diameter of Φ212.75 mm, such 5 positioning tube cleaners of 3 types as the soft tube cleaners of Φ205 mm and Φ209 mm, soft descaling tube cleaners of Φ205 mm and Φ209 mm as well as four cup tube cleaners of Φ212 mm are adopted for descaling inside pipelines. For the slurry pipeline before dredging, the water discharge was 230.45 m³/h and outlet pressure of main pump was 1 150.7 kPa, while after dredging, the water discharge was 303.13 m³/h and outlet pressure of main pump was 1 115.2 kPa under the same condition of transporting slurry so that the flow of pipeline is increased by 31.54% and outlet pressure of main pump is reduced by 3.09%. The transportation capacity of pipeline could be effectively improved and outlet pressure of main pump could be reduced with the successful applications of dredging for slurry pipeline on site, which could be as important references for descaling long distance slurry pipeline.

In the paper, the effects of adding dolomite, soft burnt dolomite and serpentine into infrared micro sintering furnace with different content levels of MgO on such properties as the fluidity of liquid phase and strength of bonding phase for iron ore powder are studied. The results showed that the sintering properties of adding soft burnt dolomite were superior to those of adding dolomite and serpentine, which mainly manifested in suitable fluidity index of liquid phase for iron ore powder within 0.6~1.2 at 1 280 ℃, the highest strength of bonding phase was 476.6 N and appropriate content of MgO was 2.0%. The sinter pot test results showed that the sinter added with soft burnt dolomite was with such advantages as high low temperature reduction degradation index, narrow drippage interval and small maximum pressure differences. The sintering of adding soft burnt dolomite is considered to be more beneficial to improving metallurgical properties of sinter based on the comprehensive comparisons of sintering properties of such three magnesium fluxes as the dolomite, soft burnt dolomite and serpentine.

In this paper, the effects of replacing iron ore concentrate of Inner Mongolia Autonomous Region with finely ground super special powder on production process and properties of pellet are systematically investigated based on the configuration of raw materials of producing acid pellet with the process of traveling grate-rotary kiln-rotating annular cooler of Baotou Steel. Meanwhile, the maximum proportion of Barun concentrate in producing pellet is explored based on the characteristics of low sulfur for finely ground super special powder. The results showed that the proportion of bentonite could be reduced obviously by adding the finely ground super special powder into pellet of Baotou Steel. When the proportion of finely ground super special powder is 10%, proportion of bentonite could be reduced from 2.0% to 1.2%, which is a significant reduction. When the proportion of finely ground super special powder is 5%~20%, performance indexes of green pellets and dry pellets could all meet production requirements of pellets. Under the condition of calcination temperature of 1 220~1 240 ℃, the compressive strengths of finished product, oxidized pellets prepared with different proportions of finely ground super special powder all reach over 2 500 N and reduction swelling rate is lower than 20%, which could meet the requirements of blast furnace production. It is suggested to produce pellets with the configuration of iron charge of 10% finely ground super special powder+50%~60% Barun concentrate+30%~40% iron ore concentrate of Inner Mongolia Autonomous Region for the process of traveling grate-rotary kiln-rotating annular cooler considering the grade of pellets and content of Al₂O₃. Under the raw material condition of 10% finely ground super special powder and 1.2% bentonite, the maximum proportion of Barun concentrate could reach 60%.

With the environmental protection and production limitation, the output of sinter is becoming increasingly tense after 1^# and 2^# sintering machines in 1^# sintering workshop are not in the production sequence as well as the addition of large proportion of pellets into blast furnace has become new development trend of iron-making. During this test, 5^# blast furnace is with trouble free operations through regulating charge level, adjusting central coke quantity and discharging sequence of feed zone, optimizing parameters of tuyere and area of inlet air, increasing heat reserve of hearth, adjusting and controlling basicity of slags as well as actively coping with various changes of furnace conditions after increase the proportion of pellets. The smelting production is successfully realized in the 1 500 m³ blast furnace of Baotou Steel with structure of furnace charge of large proportion of pellets and use ratio of pellets reaches 52%, so the fuel ratio is stable with a slight decline.

The drawing speed of welding wire is seriously affected and fracture of welding wire is easy to happen due to high nitrogen content of the ER70S-6 welding wire steel so that user requirements cannot be met. In order to reduce the nitrogen content in steel, the technological process of converter steelmaking is studied systematically as well as the factors influencing nitrogen content in steel and control measures are discussed. In the paper, the dissolution mechanisms of nitrogen in steel are analyzed by thermodynamics, restricted links of nitrogen removal are analyzed and studied by dynamics as well as the influences of sulfur content in molten iron in furnace, slag charge in top of converter, times of spot blowing for converter and maintenance of tap hole of converter on nitrogen content and corresponding measures for controlling nitrogen content in the technological process of steelmaking are studied based on the thermodynamic analysis and dynamic mechanical analysis.

The production rhythm of production line could be significantly improved and energy consumption per ton of steel of production line could be reduced by increasing hot charging and feeding rate of production line. In the paper, the characteristics of production line of hot charging and feeding for continuous casting billet of wide and thick plate of Baotou Steel are introduced. The hot charging and feeding rate of production line of wide and thick plate could be effectively increased through taking such measures as increasing the feedback speed of results for samples of compositions of molten steel in tundish and surface and internal qualities of plate blank as well as controlling hot charge cracks of steel plate.

With the continuous development of industry, the requirements of steel quality for various countries in the world are higher and higher. It has been current research emphasis how to improve the corrosion resistance of steel. The effects of rare earth elements on improving corrosion resistance of steel have been proved. In the paper, it is mainly elaborated the influence mechanisms of rare earth elements on modification of inclusions, causes of pitting, change of structure and components of rust layers as well as electrochemical corrosion resistance of low alloy steel through investigating a large number of literatures, which could provide the theoretical basis for promoting applications of rare earth elements in steel.