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 rare earth in baiyuneboite is recovered with the process of concentration-flotation-concentration-filtration in Baoshan Mining Co.. During the concentration process of concentrate, about 4% of rare earth resources are run off from overflow of concentrate, their grade is 26.17% by detection and most of their particle sizes are 5~20 μm so that they are micro-fine particles. In this paper, the overflowed concentrate of large well of concentrate in Baoshan Mining Co. is with sampling analysis. The rare earth resources are recovered with various methods as flotation, desliming flotation, magnetic concentration and gravity concentration. Finally, the rare earth ore concentrate with grade of 50.72% and recovery rate of 30.82% is obtained with the gravity concentration method, which is with significant guiding function for comprehensive recovery of rare earth resources in Bayan Obo.

The causes on lower impact toughness of weld for 10 mm thick 700 MPa grade square and rectangular welded pipe welded with high frequency resistance are analyzed with such inspection and analytical equipment as metallographic microscope, impact testing machine, scanning electron microscope and energy dispersive spectrometer. The results showed that there were such endogenous inclusions as silicate and titanium nitride as well as foreign inclusion that is mainly manganese oxide at the weld, the combined effect of which causes impact absorbing energy at room temperature of weld to be less than 8 J. Subsequently, the weld quality of square and rectangular welded pipe is improved, impact absorbing energy of weld is increased to about 20 J by taking such measures as strengthening control level of steelmaking process and increasing upset force of high frequency resistance welding. In straightening and sizing process, cracking rate of square and rectangular welded pipe is decreased from 8% to 3%.

In this paper, the process flow and problems in process of production and operation for desulfurization and denitrification system of flue gas of coke oven are introduced in detail. The operation of the system is stable, emission indexes of flue gas are acceptable, repair cycle of the system is extended so that repair frequency is reduced and hourly qualified rate per month of emission for flue gas of coke oven is guaranteed to be over 95% through taking such measures as adjusting the heating schedule of coke oven, grouting of coke oven, sealing desulfurization and denitrification system, reforming denitrification system, strengthening heat preservation of gas pipeline as well as reducing impurities in gas.

The spatial detection of rolling mill housing is the difficulty in rolling mill measurement. In the past, the measurement was with total station and inside micrometer, however, the measurement accuracy and technical indexes of this method could no longer meet the requirements of operating maintenance for rolling mill. In this paper, the method of measuring rolling mill housing with laser tracker is summarized. The centerline of rolling mill row is fitted according to the data of rolling mill housing collected by laser tracker as well as the coordinate system is established by taking the centerline of rolling mill row as the baseline so that such spatial position relationships as the centering size, window size and deflection of rolling mill housing could be obtained. The installation precision of rolling mill housing is recovered by adjusting the rolling mill housing based on the measurement data of laser tracker. This method is so reliable that it could be popularized.

For the laser cladding technology, metal powder is melted by high energy laser beam to form metallurgical bonding layer with base material, which could prepare functional coating. Its performances could be optimized through adjusting and controlling process parameters. In the iron and steel industry, the technology is applied for strengthening components and parts, corrosion prevention of equipment as well as repair of high value equipment. Such problems as peeling of cladding layer and cracks are solved by optimizing the pretreatment, process parameters and material adaptation as well as high-quality repair of complex components is realized combining the technology with such technologies as 3D scanning and robot, which could promote the intelligence of repair processes.

The composition and production process of hot rolled steel strip for CT70 grade corrosion resistant coiled tubing are independently designed and formulated as well as small batch industrial trial production is carried out. For the trial product, the yield strength is 520~522 MPa, tensile strength is 575~584 MPa, elongation is 33%~34%, microstructure is mainly ferrite +pearlite with a small quantity of bainite, banded structure is grade 1.0 and total of inclusions is grade 1.0 so that non-metallic inclusions are well controlled. The mechanical properties, resistance to hydrogen induced cracking (HIC) and welding performance indexes of steel strip for CT70 as well as the mechanical properties and hardness of coiled tubing manufactured with steel strip for CT70 could all meet the user requirements.

The stable operation of heavy duty mining truck is beneficial to safe production of mines. The failure rate of heavy duty mining truck in a mine is high and it is even higher in winter. It is found through analysis that the main causes are structural designs of accumulator and steering pump themselves for hydraulic system are not reasonable as well as control of mixture ratio of fuel to oil for engine is not accurate. The seal wear is reduced through changing single-point support to oriented multi-point support for piston of accumulator and adding unload groove; such problems as high pressure and temperature rise are solved as well as loss of parts is reduced through adding unloading valve on steering pump; temperatures of solidification point for different mixing ratios of 0^# and -35^# diesel are determined through experiments as well as auxiliary fuel tank is installed to choose different mixture ratios of fuel to oil and oil supply modes based on weather conditions. The failure rate of heavy duty mining truck is reduced through implementing the above measures.

The defect with morphology of rolling skin is found on the internal surface of Φ406 mm×8.8 mm seamless tube for gas cylinder, but longitudinal ultrasonic testing does not give an alarm, so probe of transverse flaw detector is started to detect defects and the proportion of alarm is found to be higher. The cause of transverse defect on internal surface is that the lubrication effect in rolling process of continuous mill is not good through the macro analysis, chemical composition analysis, metallographic analysis and energy spectrum analysis of defective products as well as the improvement measures for rolling method of reducing arresting force are proposed.

The rare earth inclusions in rare earth steel sample are separated from the matrix by electrolysis. The separations of rare earth sulfides, rare earth sulfur oxides and rare earth oxides are studied through different solvents, water bath time and chemical tests so that the scientific and reliable analytical method is established. The verification tests indicated that the results of precision for sample detection were good and relative standard deviation was less than 10%; for the comparative experiment of inductively coupled plasma mass spectrometry and spectrophotometry, detection results of the two methods were consistent. The analytical method could provide important technical supports for mechanism studies of rare earths in steel.