In the paper, it is proposed how to select the pipeline material and some matters needing attention in low temperature environment condition by analyzing the lowest design operating temperature of gas pressure piping in the iron and steel industry. The gas pipe in the iron and steel industry is usually with large pipe diameter and low pressure, so it is not pressure piping. With the development of new technologies, some gas pipes with pressure higher than 0.1 MPa are pressure piping. The design of material should be based on the pressure piping code. In the severe cold area, when the lowest design operating temperature of pipe is lower than -20 ℃, the applicability of materials selected for pressure piping in low temperature conditions shall be considered.

The 5th generation American Morgan technology was introduced in the early 1990s for a production line of high speed wire rod and its design capacity was 0.38 million tons. With the constant improvement of production technology and efficiency for the deep processing industry of wire rod, the requirements of dimensional accuracy, surface quality and mechanical properties for wire products in the market are higher. In order to satisfy the market changes and improve product competitiveness, the size reducing mill is added in the production line of high speed wire rod. In the paper, it is introduced the construction transformations of such types of equipment as mechanical, electrical and power as well as the roll gaps of finishing rolling unit and size reducing mill are redesigned. Moreover, the R values of each stand are given as well as different accident types and solutions after the mill put into production are summarized.

The process of blowing out by lowering the charge level is smooth. Moreover, the whole process without detonation, rapid blowing out with safety and environmental protection are realized through activating the furnace hearth, calculating and analyzing loading of light load materials, adopting high blowing rate in early stage to make coke burnt as quickly as possible, improving atomization device to reduce the amount of water injected into furnace top, refining tapping in stokehole, reasonably controlling the relationship between air pressure and blowing rate, shortening the time of gas release, efficiently organizing, safely placing residual iron and coordinating various systems.

In the paper, the recrystallization annealing process is studied by taking Fe-Mn-Al-C high manganese austenitic steel as object of study. The thermal simulation tests with series of temperatures, hardness test and metallographic analysis are carried out to the test steel. The study results showed that the recrystallization temperature was 750 ℃ when annealing holding time was 120 s and recrystallization temperature was increased to 800 ℃ when annealing holding time was shortened to 60 s. The grains remain uniform and fine as well as hardness value of test steel is with a little change when the holding time is 120 s at 750~900 ℃.

It is considered that there is no direct relation among the bubble coke rate for large capacity coke oven and the strength, ash content as well as scurf resistance M₁₀ of coke after reaction while there is certain correlation between it and coking time through their data analysis. As a result, it could not be as the evaluation index for coke quality.

The stock of medium-lean oxidized ore in Bayan Obo is huge as well as its degree of oxidation and impurity content are high. Among them, iron and rare earth are the main recovered components. The grade of iron is 28.74%, content of FeO is 1.99% and grade of rare earth is 5.45%. The iron in the ore mainly exists in forms of hematite and limonite and magnetic iron as well as the distribution ratios are 48.54% and 43.84% respectively. The qualified iron concentrate with grade of iron concentrate of 66.07% and gross recovery of iron of 87.47% is obtained by studying the ore properties of medium-lean oxidized ore in Bayan Obo as well as exploring and recycling its iron resource with the process of “preconcentration-hydrogen-based mineral phase transformation-stage grinding-stage magnetic separation”. This method is beneficial to the full utilization of iron resources and improving the utilization rate of mine resources.

The rare earth oxides of lanthanum and cerium are high-value rare earth products, they are usually packed in the packing bags of 500 kg or 1 000 kg and the bagging error is required to be less than 0.05%. At present, the manual bagging is adopted, followed by the charging mode of weighing and compensating. There are such steps for the charging process of each ton bag as hanging bag, charging, carrying, weighing and compensating, so at least 4~5 workers are needed. There are such problems as high labor cost and low production efficiency. The automatic charging machine whose charging error is less than 0.05% and supporting charging basket are developed by adopting such technologies as automation and high-precision measurement and weighing. As a result, the automatic charging for the rare earth oxide products of lanthanum and cerium is realized as well as the problems that complex process of charging rare earth oxide products and several workers needed to operate are solved so that the working efficiency is improved and labor costs are reduced.

In the paper, the production technology process and process control system of wide and thick plate mill in Baotou Steel are briefly introduced. The wide and thick plate mill is the important component for production line of wide and thick plate of Baotou Steel as well as its process control system is between the production management system and basic automation system in the plant, which is mainly responsible for managing production process data. The process control system model of rolling mill is generally divided into control part and non-control part. The emphasis of this paper is to research, analyze, optimize and adjust the rolling moment model of control part. After the optimization, the setpoint accuracy of secondary system model of roughing mill is improved and capacity of roughing mill is further increased.

In order to solve such problems as low efficiency, long time-consuming, large human input and potential safety hazards for the overall replacement of conveying belt in processing line as well as complete the overall replacement of conveying belt safely and efficiently, a set of equipment for automatically changing conveying belt is studied and designed through theoretical analysis and calculations combining with practical experiences. The equipment includes the drive system of old belt, support system of new belt and control system. After the old belt is disconnected, one end is fixed onto drive unit as well as drive system is started to export and roll up old belt, while the old belt is to import new belt. After that, vulcanize and bond the new belt. The practices prove that the automatic replacement of belt could be realized with the equipment as well as the whole process is safe and efficient, which is with wide application prospect.

The caking index of coal is one of the important indicators for evaluating plasticity of coal. In order to accurately measure the caking index of coal, the influence relations between various components of uncertainties and evaluation results of uncertainties for caking index of coal are analyzed in detail in the paper. The components of uncertainties include such influence factors as the standard uncertainty u(rep) introduced by repetitive tests, standard uncertainty u(m) introduced by weighing mass m of sample with the scale, standard uncertainty u(c) introduced by weighing coke residue during detection process of sample, standard uncertainty u(r) introduced by rotational speed of drum and standard uncertainty introduced by temperature changes of muffle furnace. The uncertainties of measurement results for the caking index of coal are obtained through calculating the standard uncertainties, which provide the basis for scientifically and accurately providing measurement results.