The chemical compositions of X52QH seamless steel pipe for hydrogen compressed natural gas transportation are designed with microalloying design based on low carbon manganese steel. The results of laboratory studies and industrial trial productions showed that the pipe was with excellent low temperature toughness and strength, its microstructure was mainly bainite +ferrite, grain size of microstructure was grade 9.0 as well as low temperature impact energy at -90 ℃ of material was 200 J when the quenched-tempered heat treatment process of “910 ℃ quenching+640 ℃ tempering” was adopted. The CTOD (crack tip opening displacement) test (-10 ℃) results showed that crack tip opening displacement>0.9 mm (required to be≥0.254 mm). In the environments with and without hydrogen, the reduction of area and elongation of slow strain rate test materials are all over 90% so that they are with good crack extension resistance and hydrogen embrittlement resistance.

In this paper, the current situations of implementation, advantages, challenges and optimization strategies for co-investment mechanism of employees in state-owned enterprises are discussed. Its connotation, characteristics and application situations in state-owned enterprises are elaborated through literature research and case analysis. It is found in the research that the co-investment mechanism of employees is with significant advantages in motivating employees, promoting enterprise innovation and optimizing governance structure, however, it is also facing such challenges as imperfect improvement and difficult risk control of co-investment mechanism in enterprises. In this paper, such suggestions as perfecting relevant systems of enterprises, optimizing system design as well as strengthening risk management and control are proposed, which could provide references for deepening reform of co-investment mechanism of employees in state-owned enterprises.

In the paper, the feasibility test of adding purchased high-silicon ore in pellet grate of Baotou Steel is carried out to analyze the changes of performances for green pellets, dry pellets and finished pellets after adding purchased high-silicon ore based on existing configuration of producing iron charge with pellet grate. The results showed that it was feasible to produce oxide pellet by adding purchased high-silicon ore in pellet grate of Baotou Steel. The performances of green pellets could meet the requirements of production processes for pellet of Baotou Steel and changes of grade of iron for oxide pellet are not great, which maintains at around 63.20% after adding 5%~10% purchased high-silicon ore in production with pellet grate. It is suggested to appropriately increase calcination temperature of pellet production in production with pellet grate of Baotou Steel under the condition that proportions of iron ore concentrate of Bayan Obo are 50% and 55% as well as adding 5%~10% purchased high-silicon ore. The compressive strength of oxide pellet produced is over 2 500 N and reduction swelling is below 20%, which could meet the requirements of blast furnace production.

The belt conveyer has been widely used in iron and steel enterprises. It is with such characteristics as long transportation time, strong transportation capacity, high safety and efficiency as well as low economic costs. In recent years, it is the key problem how to achieve safety and high efficiency in production process of iron and steel enterprises with the growing demands of transportation capacity for enterprises. The belt conveyer is important equipment for production and development of iron and steel enterprises as well as its safe operation has become an important link in the whole production chain. Once there is the failure of conveyer belt, it will seriously affect normal production of enterprises. In order to ensure the belt conveyer to be operated normally, corresponding preventive measures for tearing of belt should be taken by iron and steel enterprises. In this paper, the causes for tearing of belt for belt conveyer are analyzed, which could provide the basis for solving the problems of belt conveyer brought to production.

The iron and steel industry plays a key role in the national economy and its equipment management level is closely related to the market competitiveness and sustainable development prospects of enterprises. There are such common problems as low level of intelligence for equipment management, poor operating environment and processes are not clear in iron and steel enterprises so that traditional equipment management modes cannot meet the requirements of high efficiency, precision and intelligent management for modern iron and steel enterprises. The equipment management level and production efficiency are further improved, operating costs are reduced as well as comprehensive competitiveness of enterprise is enhanced by carrying out the life cycle management of equipment that focuses on digital construction, applications of new technologies as well as green and sustainable development.

In the paper, the effects of such factors as high load operation, excessive concentration of volatile phenols and microbial poisoning on system stability are systematically analyzed aiming at the practical problem of abnormal increase of chemical oxygen demand (COD) in effluent of biological dephenolization system of Inner Mongolia Baotou Steel Qinghua Coal Chemical Industry Co., Ltd.. The COD in effluent is successfully reduced to standard level within two months so that operation pressure of subsequent advanced water treatment system is significantly relieved by adopting such comprehensive measures as reducing load of inlet, optimizing dissolved oxygen concentration, adding COD degrading bacteria and nitrifying bacteria, supplementing alkalinity to stabilize pH value, adding pulverized fuel ash into oxic tank to adsorb toxic substances as well as adjusting the strategies of sludge return and spoil disposal.

In the article, it is discussed the effects of drying time, prepared sizes, preparation time, stirring means and storage time of samples on measurement results of caking index which are not specified in the national standard GB/T 5447—2014. Such two types of frequently-used bitumite, coking coal and gas coal are selected for experimental study. The study results showed that the effects of drying time, particle size and preparation time of samples on measurement results of G value were the most significant, the effects of analysis link and storage time of samples on measurement results of G value took second place, while the effects of stirring means on measurement results of G value were minimum. The specified control conditions of related influencing factors are given through experiments so as to achieve the goal of improving the accuracy of measurement results for caking index of bitumite.

In this paper, it is introduced the determination of oxygen content in lanthanum-iron alloy with the pulse melting-infrared absorption method. The preparation method and optimal analysis conditions are determined by studying the preparation methods of sample as well as analyzing the effects of power, weighing sample and flux on determination results of oxygen content. The standard deviation is less than 5% and recovery rate is 95%~105% for this method, so it is with good precision and accuracy.

The industrial trial production of corrosion-resistant rail is successfully realized through strictly implementing its process system of smelting, continuous casting, heating and rolling. The comprehensive detection for microstructure, mechanical performances and corrosion resistance of trial-produced rail is carried out. The results showed that the tensile strength of rail could reach over 1 050 MPa, top surface hardness of rail head (HBW) was over 300, cross section of rail was uniform perlite and trace amount of ferritic structure as well as lamellar spacing of pearlite was reduced by 21% compared with that of traditional hot rolled U75V rail. Compared with U75V rail, the corrosion resistance of trial-produced rail for simulating coastal atmospheric environment is improved by 45.3% and corrosion resistance of simulating acid rain is improved by 54.9%, which could reach the design indexes.

After the separation of iron and rare earth for ore in Main and East Mines of Bayan Obo, the content of Nb₂O₅ in rare earth flotation tailings is enriched from 0.14% to 0.19%. The bulk flotation is adopted to separate easy-floating minerals in advance so as to reduce the impacts of easy-floating minerals in desilting on subsequent niobium flotation as well as the combined process of flotation and magnetic separation that bulk flotation of tailings-selective flotation of sulfur-flotation of iron-niobium flotation of iron tailings-high intensity magnetic separation of niobium concentrate is adopted to separate niobium industrially aiming at the high content of easy-floating minerals as well as close paragenesis and inclusions of niobium minerals and iron minerals. The bulk flotation is carried out under the conditions that the proportion of size fraction of -0.043 mm for grind fineness is 90%, dosage of TD-V collecting agent is 1.0 kg/t and dosage of depressor, the sodium silicate is 2.0 kg/t, sulfur flotation is carried out under the condition that dosage of butyl xanthate is 1.4 kg/t, iron flotation is carried out under the conditions that dosage of ammonium fluosilicate is 8.5 kg/t and dosage of collecting agent, the SZ fatty acid sodium salts is 0.5 kg/t as well as niobium roughing is carried out under the condition that dosages of CMC, C_5-9 and alum are 1.2 kg/t, 2.2 kg/t and 0.72 kg/t respectively. The niobium concentrate of flotation with grade of Nb₂O₅ of 2.21% is obtained by adopting the niobium flotation process of one roughing and one concentration as well as the niobium concentrate with grade of Nb₂O₅ of 4.41% and sub-niobium concentrate with grade of Nb₂O₅ of 0.96% are obtained through high intensity magnetic separation of 1.7 T so that recovery rate of niobium metal is 34.85% with the combination process of flotation and magnetic separation.