In this paper, the dissolution methods of iron ore and slags are studied. The decomposition method of preliminarily dissolving with hydrochloric acid followed by treating the residue with mixed flux of sodium carbonate-boric acid is applied. The analytical spectral lines with high sensitivity and fewer interferences are determined as analytical spectral lines through optimizing and selecting the analytical spectral lines of lanthanum, cerium, praseodymium, neodymium and samarium by experiments. Moreover, the contents of such five elements as lanthanum, cerium, praseodymium, neodymium and samarium are determined simultaneously with ICP-AES. The results showed that the lower detection limit of lanthanum, cerium, praseodymium, neodymium and samarium in iron ore and slags was 0.005 0%, the upper detection limits of rare earth elements in iron ore were 5% for La, 10% for Ce, 1% for Pr, 2% for Nd and 1% for Sm as well as all the upper detection limits of rare earth elements in slags were 0.500%.

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.

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 the paper, the restraining factors affecting recycling fly ash of sintering machine head and blast furnace bag are discussed as well as the key technologies of extracting such valuable elements as Zn, K and Na from the fly ash are studied by analyzing its characteristics and disposal status. The technical plans for comprehensive utilization of fly ash of sintering machine head with high alkali metal content as well as fly ash of blast furnace bag with high zinc and alkali metal contents are proposed combining with such cases as salt extraction technology by washing for fly ash with high alkali metal content, zinc extraction technology with pyrogenic and wet processes for fly ash with high zinc content and reduction technology of electric arc furnace for iron-bearing dust as well as evaluating their merits and demerits. After implement the plans, the disposed fly ash could be recycled for sintering as well as products of Zn, K and Na could be sold externally so that the economic benefits are considerable and the problems of land occupation and environmental pollutions could be solved.

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.

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.

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 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.

The mineral species that have been found in Bayan Obo ore deposit are sorted and recorded based on the list of mineral species in Bayan Obo mining area in Mining and Metallurgical Technology of Baiyuneboite as well as the research achievements of minerals of Bayan Obo are collected combining with such documents as Mineralogy of Bayan Obo. The results showed that there were 172 types of minerals in the list of mineral species in Mining and Metallurgical Technology of Baiyuneboite after correct obvious errors, the minerals reached 191 types by supplementing the minerals that were not recorded in Mineralogy of Bayan Obo; a total of 209 types of minerals have been found in Bayan Obo ore deposit so far, together with the newly found minerals and new minerals.

In this article, the current conditions and development tendency of cooling bed in the production line of section steel are introduced. A new type of captation and dewatering installation for spray cooling system is designed to solve the problems in applications of spray cooling technology in production of cooling bed. Its layout and structure are mainly introduced combining with design drawings. It is with such characteristics as lower costs, shorter construction period, easier installation and convenient maintenance. With these characteristics, the advantages of spray cooling technology for temperature control in cooling process of section steel could be fully taken, the cooling effect of cooling bed on limited area is better and capacity of cooling bed is improved with the spray cooling technology, which provide reference for upgrading the spray cooling system of online cooling bed.