In this paper, it is systematically introduced the characteristics of impurity distribution for slurry pipeline and effects of pigging with different types of tube cleaner by taking the pigging and descaling for a long distance high pressure slurry pipeline of iron ore concentrate with variable diameters as an example. It is found through actual pigging that the passability of pipeline could be preliminarily detected with soft foam pig and mechanical tube cleaner with leather cups of different shore hardnesses. In addition, the effect of cleaning scale for slurry pipeline with foam pig is poorer, so the mechanical tube cleaner with stronger pigging ability should be preferred, which is with important guiding significance for pigging of similar slurry pipelines in the future.

The IF (Interstitial Free) steel plate is welded into steel pipe for manufacturing condenser pipe of household appliances by a user. There are local spot defects on the surface of steel pipe when it is subjected to conventional hydrostatic test. Such tests on chemical compositions, microstructure of defect and non-metallic inclusions of spot defects as well as mechanical properties and metallographic microstructure of the steel plate with base metal are carried out with such means as metalloscope and scanning electron microscope. The results showed that there were abnormal microstructures at the spot defects. The abnormal microstructures contain such alloying elements as Cr and Ni, which are different from the chemical compositions of matrix. When foreign matter is pressed into welded pipe, its local stress is concentrated. During hydrostatic test, the leak points of pressuring are at the foreign matter which is weakly combined with matrix. In order to avoid such surface defects, it is necessary to strengthen quality monitoring during the whole production and processing processes of welded pipe to prevent foreign matters from pressing into matrix to destroy its continuity so that the steel quality is reduced.

The industrial production process of rare earth steel involves the problem of yield of rare earth and stable yield is the important guarantee for stable performances of rare earth steel products. The effects of addition of position, addition amount and composition of liquid steel (oxygen activity, sulfur content) on yield of rare earth for rare earth steel are studied by adding rare earth in ladle and sampling analysis of tundish. The results showed that the yield of rare earth was increased in turn by adding rare earth in ladle, tundish and crystallizer; the larger the addition amount of rare earth alloy before off-position of ladle furnace, the lower the yield; the higher the contents of oxygen and sulfur in liquid steel, the lower the yield of rare earth.

In order to eliminate the hidden dangers of rock falling and slope slide on slopes in Main Stope and East Stope of Bayan Obo Iron Mine as well as improve slope stability, the stability analysis of the slopes in Main Stope and East Stope of Bayan Obo Iron Mine is carried out. Such modes of slope treatment as full-length grouted bolt+shotcrete with wire mesh on slope surface+drainage opening, drainage with drainage opening and pre-stressed anchor cable+reinforced concrete retaining wall+rib column+drainage opening and pre-stressed anchor cable+half lattice girder+shotcrete with wire mesh+drainage opening are taken to reinforce the sectors with rock falling or slope slide in Main Stope and East Stope of Bayan Obo Iron Mine. Moreover, such slope monitoring systems as artificial monitoring, total station monitoring, slope radar, fracture meter and global navigation satellite systems (GNSS) receiver as well as corresponding safety management system are established to ensure the slope stability and safe productions of the mine.

There is cracking failure at the weld seam of high strength and toughness 490CL wheel steel rim made with flash butt welding during flaring and forming process. Its causes are analyzed through macroscopic and microscopic observations of fracture morphology, tests of chemical compositions, mechanical properties, microstructure and microhardness as well as energy spectrum composition analysis. The results indicated that there were certain area of welding “gray spots” mainly composed of manganese oxide at weld failure so that the weld ductility was reduced. As a result, there is cracking at weld fusion line during flaring and forming process of welded rim. The weld quality of 490CL wheel steel for rim is improved by adjusting such welding parameters as reducing flash allowance and increasing pressure of upset forging so that the proportion of weld failure during forming of rim is reduced from 1.5% to 0.3%.

There are often such phenomena as spillage, firing, scratch of foreign objects and blockage as well as such failures as off tracking, slipping, scratch and tearing for conveyor belt of iron and steel enterprises. Moreover, the causes of various failures are analyzed, advantages and disadvantages of using various switches for belt failure detection are compared, a method of detecting various failures with images is proposed as well as adaptability of 2D and 3D image detection methods are compared. At last, the architecture of establishing intelligent belt detection platform for iron and steel enterprises is briefly described.

Such effective measures as adopting optimum parameters of power transmission, forming refining white slag with microfoam as early as possible, optimizing modes of bottom blowing, accurate temperature control as well as optimizing dust removal control and electrode wrench are taken through experiments of multiple heats aiming at such phenomena as oxidation, melting loss, thermal vibration and drop out of electrode easily occurred during the heating process of ladle furnace. As a result, the consumption of electrode for ladle furnace is decreased from 0.544 kg/t in 2021 to current 0.347 kg/t so that stable and trouble-free operations of smelting for ladle furnace is ensured as well as cost decreasing and benefit increasing and high efficiency continuous casting are achieved.

During the stamping process of components and parts of computer case, there is blackening phenomenon on the surface of galvanized fingerprint resistant plate of Baotou Steel so that the appearance quality after spraying by user is seriously affected. The microscopic morphology of galvanized plate after stamping is analyzed by microscope and scanning electron microscope (SEM) aiming at the defect. The results showed that the passivation film on the surface of galvanized plate of Baotou Steel dropped out during stamping process as well as the exposed Zn oxidized and turned black. It is effectively solved by adjusting film thickness and proportion of poly tetra fluoro ethylene in passivating liquid.

In this paper, the sealing device for patchhole of oxygen lance is redesigned based on the infinite space submerged turbulent jet theory and characteristic test of dominant frequency of oscillation for double-hole jet aiming at such phenomena as spill over of flue gas and flare-up often occurred at nitrogen sealing at oxygen lance of gasification cooling flue for converter. The new nitrogen sealing device adopts the design of seal chamber and double row of inclined holes are set on nitrogen seal seat as well as the aperture and angle of inclined hole are reasonably designed combining with theoretical calculations. It is applied on new 1^# converter of Steel-making Plant of Baotou Steel, in which the phenomenon of “smoking” in process of converting at oxygen lance as well as the frequency of cleaning and changing nitrogen seal cap for operators are reduced so that recovery amount of coal gas is improved. The engineering applications show that the modified sealing device is with such advantages as reasonable design, simple equipment and safe operations.

In order to remove the calcium and magnesium ions in ammonium sulfate wastewater, ensure subsequent trouble-free operations of water treatment process, improve quality of ammonium sulfate solid and recover magnesium resource, the calcium and magnesium ions in ammonium sulfate wastewater are removed with solvent extraction method in experiment. The P₂₀₄ and kerosene are used as extractant as well as pH value of ammonium sulfate wastewater and saponification degree of P₂₀₄ are adjusted so that the step-by-step removal of calcium and magnesium ions in ammonium sulfate wastewater is realized. The data support for industrial applications of this method is provided by such experimental conditions as determining pH values of the solution and comparing.