Study of iron content in iron ore concentrate increasing effect on sintering process indices and on metallurgical properties of sinter

Effectiveness of blast furnaces operation in many respects depends on metallurgical properties of agglomerate, in particular, iron content in the sinter and its basicity. At the same time, it is accepted that usage of iron ore concentrates with iron content more than 66–67% for sinter production results in decreasing of its strength. As a result of the planned modernization of the technological sections of the concentration plant JSC “Stoilensky GOK”, iron content in the concentrate will be increased to 68–70%. It makes it actual to accomplish comprehensive studies of metallurgical properties of the sinter while increasing iron content in the raw material. Results of the study of sinter properties presented, the sinter being obtained with utilization of iron concentrate with iron content 66.6 % (base), 68.0 and 69.2 % (exp. 1 and exp. 2 correspondently). The iron ore mixture for all the stages was the same and consisted of iron ore concentrate – 78.3%, sintering ore – 8.0%, lime – 5.5% and sintering additives (sludge, dust, scale) – 8.2%. The sintering mixtures composition for all the study stages differed only by fluxes and iron ore mixture consumption. 18 test sintering operations at three values of basicity 1.6, 1.8 and 2.0 units were accomplished. It was established that increase of iron content in the concentrate and basicity of the sinter results in improving of the sintering process indices, increase of the vertical sintering rate, sintering machines productivity, recovery and the sinter cold strength. Increase of the sinter basicity and its production with increased content of iron results in improving RDI indices at low temperature reducing. Results of the study of porosity indices and metallurgical properties of the sinter presented, in particular the collapsibility during reducing and temperature interval softening-melting presented. The advisability of concentrate with increased iron content utilization in the iron ore mixture shown.

Optimization of the Process of Unloading of Iron Ore Raw Materials: The Case of a Steel Plant

The process of unloading iron ore raw materials of the metallurgical plant to the sinter plant has not been considered for a long time as a particular topic. Over the last years the conditions of metallurgical production have undergone certain changes: its intensification has occurred, which entails the need to re-evaluate parameters of stable operation of sinter production. The objective of the suggested study is to consider the issues of possible technical and technological improvement harmonizing transport flows with the requirements of the main production process. To achieve this goal, a technique of mathematical modelling is used, based on the mathematical apparatus of linear programming; graphic-analytical method; method of probability theory.The issues of the process of unloading, storage of iron ore raw materials, of their preparation for sinter production are primarily considered.The article presents the main positions of the process of optimizing unloading of sinter batch of a metallurgical plant.The general characteristics of the technology of metallurgical production and of each particular process are described. The agglomeration process is considered in more detail. The tables of initial iron ore raw materials for sintering production for certain reporting periods are given, for the sake of clarity, the data of one of the tables are summarized in a diagram. A diagram of a standard trestle-type ore warehouse is considered, which sequentially shows the main processes of sintering production from supply of raw materials to the car dumper to getting through a belt conveyor into a stack, and then into receiving bins. The article also provides an example of formation of piles of iron ore raw materials using manganese limestone.The study is based on a dynamic transport problem with delays (DTPD), which considers time of transportation of goods, the dynamics of production volumes over time, the dynamics of consumption, the dynamics of stocks of suppliers and consumers, dynamics of cost of transportation and storage, dynamics of cost of consumption losses. The study contains several mono-problems with a mono load, which overlap each other, forming a multiplicative overlay of single-product problems.

Manganese Sinter Production with Wood Biomass Application

A large amount of finely dispersed manganese ore left after benefication operations or blown out from the furnaces is unsuitable for direct use in electric furnaces and blast furnaces, therefore it is necessary to granulate it in order to have the efficient use of its fine ore particles in metallurgy. To make our research more of practical use, we found it is reasonable not only work over manganese fines sintering but also to attempt mitigating the negative effect on the environment produced by the further sintering and apply the biofuel within the total fuel mass. Under laboratory conditions, the studies have been carried out with the objective to obtain manganese sinter, in which wood biomass is applied, namely initial and pre-pyrolyzed, at temperatures of 673, 873, 1073 and 1273 K. The amount of biofuel in the sinter blend was 25 wt.%. It has been established that the biomass use causes the decrease in the specific capacity of the sintering plant. However, for the efficient manganese ores sintering process, the biofuel of high pyrolysis temperature of 1273 K is required. To achieve the specific capacity and the yield to be as high as those when coke breeze is only used, the amount of the biofuel for manganese ore sintering should be less than 25 wt.% of the solid fuel. Additionally, it has been revealed that the further increase in the biofuel ratio in the total fuel amount is possible on condition that its reactivity is decreased, or larger particles of the biofuel are used.

Automatic System Design Humification of Sinter Burden in Aglomeration Shop JSC «Ural Steel»

The authors propose a comprehensive solution to decrease in humidity control sinter charge sinter shop JSC Ural Steel. The main task of sinter production is the maximum productivity of the sinter machine with a sat-isfactory agglomerate quality. One of the key parameters affecting the sinter belt performance is the moisture content of the humidity sinter. Changes in the granulometric and chemical composition and physical and me-chanical properties of the components of the charge necessitate the search for new values of the optimum hu-midity of the charge. A system for automatic control of sintering machine productivity has been developed. Au-tomatic control is based on the principle of operation of a stepping type extreme regulation system with memo-rizing the extremum (maximum) of the output parameter. The simulation of the pump electric drive is implement-ed based on the developed automatic control loop for the moisture content of the sinter charge. Implementation of the proposed system for automatic wetting of the sinter charge will increase the productivity of the sinter machine by 1,4 % while reducing the water consumption by 1,7 %.

Use of magnesian fluxes of the Khalilovo deposit in sinter production

The article describes the magnesian fluxes properties of the Khalilovo deposit with different proportions of magnesite and serpentine. The results of laboratory experiments on the effect of these fluxes with various magnesite contents on the parameters of sintering process of the Kursk magnetic anomaly ores at JSC “Ural Steel” are presented. The use of experimental magnesian fluxes of the Khalilovo deposit increases the sinter strength, yield and sinter productivity. With the use of experimental fluxes instead of Bakal siderite, an increase in the sinter yield of 3 – 5 % (rel.) can be reached. In addition, the sinter productivity increases from 1.04 to 1.08 – 1.15 t/(m2·h), that is, by 4 – 10 % (rel.). The use of experimental magnesian fluxes increases the sinter strength: the tumbler index (+5 mm) increases by an average of 4 – 6 % (abs.), and the abrasion index (–0.5 mm) decreases by 0.6 – 0.8 % (abs.). Improving the strength characteristics of the sinter using magnesian fluxes of the Khalilovo deposit is due to the formation of “reinforcing” ferritic binder, as well as due to homogenization of the solidifying melt and its crystallization in the form of glass phase of the rankinite composition, which together limit the formation of β-Ca2SiO4 . The results of experimental sintering have confirmed the possibility of using experimental fluxes in the sintering production at sinter plant of JSC “Ural Steel” without changing the production technology. The rational variant for JSC “Ural Steel” is 50 % of magnesite of Khalilovo deposit in sinter rawmix. Replacement of the Bakal siderite in the production of sinter with 2 % of MgO on the magnesian flux of the Khalilovo deposit with 50 % of magnesite provides an increase in yield by 4 – 5 %, an increase in sinter strength by 5 – 6 % and an increase in sinter productivity by 8 – 10 % while keeping the iron content at the level of the “base” period.

Main stages of the technology and equipment perfection at JSC EVRAZ ZSMK sintering plant

Data on sintering plant of OJSC EVRAZ ZSMK, its structure, stages of construction, main designing solutions, operation indices and structural changes presented. Main directions of technology and equipment perfection shown. From the moment of the sintering plant putting into operation, it operated by the designed plan, which met the existing in early 70th of the former century requirements of fluxed sinter production technology. Later the flowchart, technology and the aggregates subjected to considerable modifications. The main efforts of researchers and the plant personal developments directed on the study of the burden components and obtained sinter properties, elaboration of a technology of new kinds of raw materials sintering, optimization of main parameters of the sintering process technological regime, external heating and the burden components preparation. Besides new technological units and equipment implemented and their operation modes mastered, as well as that of process intensification. In addition, the plant personal paid much attention to the sinter quality and technical and economic indices improving, to ecology and wastes utilization, as well as elaboration of a technology of special kinds of sinter production after BF No. 2 stop and some capacity releasing. At present, the two-layer burden sintering technology mastered at all the sintering machines with the layer height500 mm. The work on modernization of the main and auxiliary plant equipment accomplished continuously. Automated control systems widely used at the plant to control the following: the quality of the incoming raw materials, supply and consumption of raw materials, calculation of the stacks, concentrate liming, the burden components and fuel dozing, the burden moistening, the burden preparation and sintering, the plant running, sinter and energy carriers accounting as well as information and technological circuit. At present, a big volume of work planned, directed on polluting substances emissions lowering, volume of production increasing and sinter quality improving, as well as production and operation costs decreasing.