Blast Furnace Burden Research Articles

Optimization of agglomeration burdens by metallugical properties complex Report 2. Optimization of BF burden components by their complex high temperature properties

Along with strength characteristics of agglomerated raw materials, its high temperature properties - the degree of reducibility, softening-smelting temperature and melt filterability through coke filling - have a great influence on technological indices of BF process. Knowledge of the properties change regularities is and actual task for through optimization of blast furnace burden composition aimed at BF smelting intensification. Blast furnace burden composition influence on reducibility, temperature interval of softening-smelting, viscosity of intermediate slags, filterability heat products through coke filling and desulphurization ability of intermediate slags studied. Influence of BOF nickel slag additions on complex of high temperature properties of iron ore raw materials estimated. Influence of pellets portion in BF burden on the process of BF slag filtration considered. It was shown, that increase of pellets portion in the burden results in slag filterability through coke filling decrease during the BF burden smelting. A favorable role of BOF nickel slag in agglomeration and blast furnace processes of JSC “ArcelorMittal Temirtau” determined. Analysis of the data obtained showed that Sulphur content in hot metal during slag sinter smelting depends practically only on intermediate slag basicity. Range of main components content in the iron ore raw materials determined, as well as contents of sinter and blast furnace burdens of JSC “ArcelorMittal Temirtau”, having most favorable complex of high temperature properties and to a great extent meeting the requirements to the iron ore raw materials.

Reduction behavior of vanadium-titanium magnetite carbon composite hot briquette in blast furnace process

The reduction behavior of a new type of blast furnace burden named vanadium‑titanium magnetite carbon composite hot briquette (hereinafter abbreviated as VTM-CCB), including fraction of reaction (f), reduction shrinking, crushing strength after reduction, phase transformation of valuable elements, and softening-melting-dripping behavior, were investigated with simulating blast furnace conditions in laboratory in this article. The reduction process of VTM-CCB could be divided into four stages. The devolatilization of the coal and the reduction of magnetite to wustite mainly occur successively in the first two stages. In the third stage, the reduction rate is much higher than that in the second stage due to the high carbon gasification rate. The reduction of Ti-bearing iron oxides occurs in the final stage. The shrinking of VTM-CCB samples is caused by the removal of carbon and oxygen and the suppression of the growth of iron whiskers during the reduction of wustite to metallic iron. The crushing strength of VTM-CCB after reduction is found to decrease from 1800 N to 600 N correspondingly with increasing temperature from 600 °C to 1100 °C. The loss of the crushing strength correlates to the pyrolysis of the coal, the carbon gasification, and the reduction of iron oxides. The phase transformation of valuable elements during reduction could be described as follows: Fe3O4 → FeO → Fe; Fe2.75Ti0.25O4 → Fe2.5Ti0.5O4 → (Fe2TiO4) → FeTiO3 → (FeTi2O5) → TiO2. The softening-melting-dripping behavior and permeability of mixed burden is improved obviously with charging a certain amount of VTM-CCB. However, the precipitation of Ti(C,N) would deteriorate the dripping behavior of packed bed when VTM-CCB charging ratio exceeds 20%.

A Case Study on Large-scale Grate-kiln Production of Fluxed Iron Oxide Pellets: Zhanjiang Pelletizing Plant of BaoSteel

ABSTRACTThere has been increasing demands for large-scale pelletization equipment recently in order to improve the composition of blast furnace burden, conserve energy and reduce emission. Accordingly, the BaoSteel built the Zhanjiang palletization plant with the capacity of 5 million-tons per year, which holds the record in the world for the largest grate-kiln to produce fluxed pellets. The features included preprocessing raw materials with the combination of ball mills and high-press roller presses, production of fluxed pellets with limestone, pre-mixing of dust wastes, and advanced desulfurization technologies. This plant has marked an important step in the development of grate-kiln pelletization technology.

A Light Field Imaging Based Measuring Method for Blast Furnace Burden Distribution

Accurate height and distribution of blast furnace burden is essential to improve coke-ore ratio, improve gas flow and reduce CO2 emission. However, conventional burden distribution measure method by mechanical sounding rod can only measure 2 or 3 fixed discontinues burden height information. This article uses a light field imaging system to estimate blast furnace burden distribution. At first, the light field camera is used to obtain 4D image of the burden surface, light position and angle information is utilized to refocus to obtain focal stack images. Then the depth of burden surface is obtained by finding out the refocused image to target depth based on laplacian operator. At last, the whole burden surface is reconstructed in Csharp/emgu platform to extract burden surface distribution and radial burden distribution.

Environmental and Technological Aspects of Converter Slag Utilization in Sintering and Blast-Furnace Production

The paper presents calculation results for predictive conditions of blast furnace operation with the use of converter slag in the iron ore portion of the blast furnace burden. It shows that addition of converter slag in the sinter and blast-furnace burden without correction of the operating conditions is not reasonable as it significantly worsens parameters of blast furnace operation. Long-term operation of blast furnaces with addition of converter slag in the burden will be accompanied by gradual accumulation of phosphorus in metal and will lead to increasing problems regarding phosphorus removal at the converter production stage. The use of converter slag makes it possible to increase the consumption of non-fluxed pellets without changing the sinter basicity and improve parameters of blast-furnace smelting. The problem of efficient and continuous use of converter slag in blast furnaces can be solved by the complex analysis of this problem: evaluation of economic feasibility of its use as a fluxing agent; feasibility study of this issue for the “blast-furnace production – converter production” complex; analysis of environmental problems during operation at the factory and in the region.

EID‐Estimation‐Based Periodic Disturbance Rejection for Sintering Ignition Process with Input Time Delay

AbstractSintering plays a key role in generating blast furnace burden in metallurgical processes. The continuous production and stable quality of sintering significantly depends on the stable and precise control of sintering ignition, which, however, is achieved through an input time delay system, and suffers from different and unknown disturbances. To reject disturbances and enhance the control precision of ignition temperature, this paper introduces a modified equivalent input disturbance (EID)‐based disturbance compensation that is suitable for controlling sintering ignition. First, the periodic properties of disturbances induced by gas pressure fluctuations are obtained based on spectral density decomposition. Second, to obtain the dynamics of sintering ignition, an iterative subspace modeling method is developed, which estimates not only the model parameters but also the length of time delay. By considering the periodic property, a control structure of sintering ignition based on the modified EID‐based compensation is proposed, in which an additional time‐delay element is designed to make the phase difference between EID estimation and real disturbance close to zero. Finally, the validity of the proposed method is verified by a simulation.

Preparation and Optimization of Vanadium Titanomagnetite Carbon Composite Hot Briquette: A New Type of Blast Furnace Burden

A new type of blast furnace burden, named VTM-CCB (vanadium titanomagnetite carbon composite hot briquette), is proposed and optimized in this paper. The preparation process of VTM-CCB includes two components, hot briquetting and heat treatment. The hot-briquetting and heat-treatment parameters are systematically optimized based on the Taguchi method and single-factor experiment. The optimized preparation parameters of VTM-CCB include a hot-briquetting temperature of 300°C, a coal particle size of <0.075 mm, a vanadium titanomagnetite particle size of <0.075 mm, a coal-added ratio of 28.52%, a heat-treatment temperature of 500°C and a heat-treatment time of 3 h. The compressive strength of VTM-CCB, based on the optimized parameters, reaches 2450 N, which meets the requirement of blast furnace ironmaking. These integrated parameters provide a theoretical basis for the production and application of a blast furnace smelting VTM-CCB.

Thermodynamic stability of SFCA (silico‐ferrite of calcium and aluminum) and SFCA‐I phases

AbstractSilico‐ferrite of calcium and aluminum (SFCA) and SFCA‐I phases form in iron ore sintering operations. Their behavior in blast furnaces, with sinter being a significant component of blast furnace burden, is of critical importance to the ironmaking process. They have complex disordered crystal structures and form over a range of composition. In the present work, enthalpies of formation from oxides for five different SFCA compounds and one SFCA‐I phase were measured by oxide melt solution calorimetry in molten lead borate solvent at 800°C. The enthalpies of formation from binary oxides are zero within experimental error for SFCA phases and slightly endothermic for SFCA‐I, confirming that SFCA phases are stabilized, not by energetics, but by their configurational entropies resulting from atomic site disorder. In addition, enthalpies of drop solution into a molten slag at 1450°C were measured for SFCA phases and show good agreement with values predicted using the heats of formation and previously measured drop solution enthalpies for the binary oxides. This agreement confirms data consistency and shows that the presence of variable amounts of SFCA relative to binary oxides in a sinter will have negligible effect on the heat balance in the blast furnace.

The effect of particle size on green pellet properties of iron ore fines

Recently, the grade of iron ore deposits has deteriorated and further development of low grade deposits is desired. Presently, the most effective and often followed route taken to utilize such deposits is the provision of beneficiation plants for upgrading iron ore and pelletizing plants for agglomerating. The iron ore fines cannot be directly used in the blast furnace as they severely reduce the permeability of the blast furnace bed and bring down the efficiency of the furnace. To overcome this, agglomeration of high grade iron ore fines is done to serve as blast furnace burden. Both the beneficiation and pelletization techniques are key process in utilization of low grade iron ores. This study deals with the beneficiation and agglomeration of the low grade iron ore; up to the extent such that it becomes an ideal blast furnace feed. Effect of particle size on pellet quality during pellet making has also been aimed and studied along with the development of flowsheet for beneficiation of low grade iron ore.

Optimization of Particle Size and Specific Surface Area of Pellet Feed in Dry Ball Mill using Central Composite Design

Objective: The dimensional properties of iron ore pellet feed including specific surface area and particle size distribution in the ball mill was studied using response surface area method. Methods/Statistical analysis: The effect of the operational parameters of dry ball mill including ball charge (20-40%), grinding time (30-50 min) and balling distribution (Small, Mixed and Large) on dimensional properties of pellet feed was meticulously examined and optimized using response surface methodology based on Central Composite Design (CCD). Responses were 80% passing size (D80) and Blaine (BL). A total of 30 grinding experiments were designed and carried out in the CCD method. Regression models and response surfaces were obtained for each response. Findings: The results predicted by these models showed good agreement with experimental values. In the studied range it was deduced that D80 is decreased and BL increased when grinding time and ball charge increased. Also, the production of fine particles improved using balling distribution of level B (mix balls), instead of one ball size distribution. 3D graphs were applied to visually evaluate each parameter effect on responses. The optimum conditions of ball mill operational parameters to reach the best pellet feed for each blast furnace burden and direct reduction iron (DRI) pellet feed were revealed using CCD optimization. The predicted values BL and D80 were found to be in a reasonable agreement with the experimental values, with R2 as correlation factor being 0.91 and 0.92 for BL and D80, respectively. Improvements: The optimum condition for having a suitable blast furnace burden was: Ball distribution level B, Ball charge= 21.8-22.4 %, Grinding time= 40.1-42.9 min. Also, the optimal condition for DRI pellet feed preparation was: Ball distribution level B, Ball charge= 21.8-22.1 %, Grinding time= 42.1-44.6 min.

Optimisation of the blast furnace burden based on its primary slag formation behaviour

The iron ore consumption doubled several times due to the rapid development of ironmaking industry in China, resulting in the worse quality of iron ores in the past decade. Therefore, the efficient utilisation of poor quality iron ore resources is of great importance for the sustainable development of ironmaking industry. In this work, a new method for optimisation of blast furnace burdens was studied based on the primary slag formation behaviour because it has significant influence on the formation of the cohesive zone. The results showed that there was obvious interaction between sinter and acid iron ores at high temperature, and the primary slag formation behaviour was clearly improved by the high temperature interaction. The poor quality lump ore could be utilised together with high basicity sinter and self-fluxed pellet to enhance the high temperature interaction. Besides, increasing CaO and MgO content in blast furnace burdens would further improve their primary slag formation behaviour and the performance of cohesive zone.

A Novel Device for Optical Imaging of Blast Furnace Burden Surface: Parallel Low-Light-Loss Backlight High-Temperature Industrial Endoscope

Accurate real-time optical imaging of the burden surface shape plays an important role in improving the gas flow distribution, reducing the coke ration, and reducing the emissions of a blast furnace. To overcome the high-temperature, high-dust, and lightless environment and obtain clear images of the burden surface, a parallel low-light-loss backlight high-temperature industrial endoscope is developed. The design of a parallel low-light-loss backlight path and a high-light-efficiency, low-light, color backlight source overcomes the lightlessness issue. Combined with the endoscopic optical imaging method, a high-temperature resistant image-capturing lens and a high-temperature non-resistant photosensitive chip are separated at two ends of the instrument. This separation design method together with the water cooling and industrial nitrogen cooling system enables the equipment to overcome the high temperature issue. Moreover, a new installation strategy, which avoids the material flow and high-dust region, is proposed to overcome the high dust issue. The strategy includes establishing a trajectory model of dust particles to determine the low-dust area and conducting a landing points experiment and a trajectory model of the material flow to determine the no-material-flow region. The industrial experiment results indicate that the developed device obtains real-time images of the burden surface and exhibits clear details of the coke and iron ore particles. The application also demonstrates the validity and better imaging performance of the proposed method compared with conventional detection methods.

Design and optimisation of charging ingredients and structure in an ironmaking system (Part II)

In order to maximise the reduction of pig iron cost in an ironmaking process, and at the same time ensure the output and quality of the pig iron, a design and optimisation system for the charging ingredients and structure in an ironmaking system was established using metallurgical theory. The system includes six modules, namely, sinter metallurgical performance testing and analysis, sintering burdening design, sinter component and property prediction, blast furnace burdening design, blast furnace batching calculation and ironmaking system burden optimisation. Based on actual production, testing and material balance theory, the system integrated these modules on VB and MATLAB using a series of intelligent algorithms, such as the BP neural network, multiple objective linear programming, genetic algorithms and so on. As a result, the optimum burden composition and structure of the sinter and blast furnace that satisfied all the constraint conditions could be obtained. Standing as a pinnacle of the global ironmaking production, the system can design and optimise not only the sintering burden, but also the blast furnace burden. Compared with the traditional production testing and hand calculation in the ironmaking system, the project can greatly reduce the production risk and greatly increase the calculation accuracy. Industrial application shows that the system is especially beneficial to reduce the ironmaking cost and at the same time ensure the output and quality.

Evaluating the Reduction-Softening Behaviour of Blast Furnace Burden with an Advanced Test

Evaluating the Reduction-Softening Behaviour of Blast Furnace Burden with an Advanced Test

Preparation of pre-reduced pellet using pyrite cinder containing nonferrous metals with high temperature chloridizingreduction roasting technology—Effect of CaCl2 additive

The role of CaCl2 during the high temperature chloridizing-reduction roasting process was investigated, aiming at acquiring high strength blast furnace burden with high iron grade and low nonferrous metals content. The effects of CaCl2 dosage on pelletizing, preheating and reduction were investigated. The results show that CaCl2 can improve the wet drop strength but reduces the thermostability of pyrite cinder green balls. When the dosage of CaCl2 exceeds 1%, the compressive strength of preheated pellets decreases while the growth of iron oxide particles is improved. Furthermore, the compressive strength of pre-reduced pellets increases but the metallization degree of pre-reduced pellets decreases with CaCl2 additive. The removal tests indicate that Zn can be removed completely without CaCl2 additive, Cu is removed only under the condition with CaCl2 additive and part of Pb must be removed by CaCl2 additive.

BLASTDAR—A Large Radar Sensor Array System for Blast Furnace Burden Surface Imaging

In this paper, we present a radar sensor system for real-time blast furnace burden surface imaging inside a fully operative blast furnace, called BLASTDAR, the blast furnace radar. The designed frequency-modulated continuous-wave (FMCW) radar sensor array operates in the frequency band around 77 GHz and consists of several nonuniformly spaced receive and transmit antennas, making it a multiple-input multiple-output radar system with large aperture. Mechanical steering is replaced by digital array processing techniques. Off-the-shelf automotive-qualified multichannel monolithic microwave integrated circuits are used. By means of this configuration, a virtual antenna array with 256 elements was developed that guarantees the desired angular resolution of better than 3°, and a range resolution of about 15 cm. Based on the single-channel FMCW signal model, this paper will derive a multichannel signal model in combination with a digital beamforming approach and further advanced signal processing algorithms. The implementation of a simulation tool covering the whole design process is shown. Based on these simulation results, a system configuration is chosen and the obtained setup is defined and presented. A description of the manufactured cost-efficient radio frequency and baseband boards together with the housing design shows the practical implementation of the sensor. For the system calibration, two different methods are listed and compared regarding their performance. Verification measurements confirm the predicted performance of the developed sensor. Several measurements inside a fully operational blast furnace demonstrate the proper long-term functionality of the system, to the best of our knowledge, for the first time worldwide. It is in continuous operation since about two years in blast furnace #5 of voestalpine Stahl GmbH, Linz.

Mathematical modeling of blast furnace burden distribution with non-uniform descending speed

The burden distribution is directly related to efficiency and stable blast furnace operation. In this paper, a mathematical model for estimating the burden distribution was developed with the combination of the falling curve sub-model, stock-line profile formation sub-model and burden descending sub-model. In a blast furnace, the burden descending velocity may be non-uniform along the radial direction due to the shaft angle and non-uniform consumption of the burden material. The modifications on two existing burden descending models, i.e., geometric profile (GP) model and potential flow (PF) model are proposed to consider non-uniform descending speed. The proposed non-uniform descending models are validated with published experiment results of scaled blast furnace. The accuracy increases notably for the modified models with the non-uniform descending velocity when compared with the original uniform descending model. In addition, the GP model and PF model are compared. The results produced by the two models are very similar. For modeling the burden descending process, both the GP model and the PF model could predict the burden profile in the upper part of the shaft. However, the PF model is capable to capture the burden distribution in case of irregular wall geometry such as scab buildup and erosion of the refractory. The effects of the non-uniform descending velocity on burden distribution in blast furnace are discussed.

Preparation of BF Burden from Titanomagnetite Concentrate by Composite Agglomeration Process (CAP)

Titanomagnetite concentrate with high-TiO2 content, is endowed with poor sintering property due to the coarse granularity and poor hydrophilicity compared to the conventional TiO2-free iron concentrates. In this study, Composite agglomeration process (CAP), an innovative route for preparing blast furnace burden, was introduced to overcome the difficulties in titanomagnetite concentrate sintering. CAP results showed that the sinter yield of 75.52%, tumbler index of 62.87% and productivity of 1.633 t·(m2·h)−1 were achieved in a laboratorial sinter pot. They are 17.38%, 13.08% and 17.82% higher than those of traditional sintering process (TSP) respectively. Moreover, CAP lowered solid fuel consumption by 3.52 kgcoke/tproduct. In addition, the reduction disintegration index of the product (RDI+3.15) was improved by 20.61%, while reduction index (RI) was decreased by 4.34%. In the CAP process of preparing BF burdens from titanomagntite concentrate, very few perovskite was generated in the pelletized part of CAP product for low CaO content. In the matrix part of CAP product, a large number of SFCA generated after perovskite fully crystallized from sinter melting for ultra-high CaO containing, thus the negative effects of perovskite on sinter quality were offset by SFCA for its excellent bonding property. Some melting phases in matrix part permeated through the outer layer of pellets and formed an interweaving structure, which bonded the pelletized part and matrix part together. As a results of this kind of mineralization mechanism, the high strength and excellent RDI property of CAP product were obtained, which proves that CAP is an effective agglomeration measure treatment for titanomagnetite concentrate.

Multi-model control of blast furnace burden surface based on fuzzy SVM

Abstract Burden distribution is one of the key procedures of blast furnace operation. The improvement in control quality of the entire charging process for blast furnace is very necessary for more competitive and profitable production. In this paper, burden surface data from radars are classified by using k-means clustering algorithm to set up the multiple models set. Given objective burden surface, multiple burden distribution control strategies are obtained. In every charging period, real time burden surface data will be processed to match the model in model set by fuzzy support vector machine, and the optimal control strategy based on the matched model will be switched in action. Finally, blast furnace closed-loop control can be realized by this way. The proposed control method is applied to a blast furnace in an Iron and Steel Plant, energy saving and consumption reduction have been achieved greatly in this operation process.

Influence of sinter basicity (CaO/SiO2) on low and high alumina iron ore sinter quality

Iron ore sinter, constituting a major proportion of blast furnace burden, significantly impacts the blast furnace performance. The chemical composition of iron ore fines, particularly alumina, sinter basicity and sinter MgO together with the thermal conditions that sinter blends are subjected to play an important role in the formation of mineral phases in sinter. To increase the sinter proportion (70–80%) in blast furnace, lowering of CaO in sinter mix is a vital parameter to balance the flux supply without affecting the slag volume and productivity. At present, the alumina content in the sinter grade iron ore fines at JSW Steel varies from 4 to 6%. The quality of iron ore presently being used calls for extensive investigations to produce low basicity sinter with high alumina iron ore. Studies have been carried out on low and high alumina iron ore fines to know the influence of sinter basicity and fuel (coke breeze) addition on sinter mineralogy, properties and productivity. It is found that with increase in sinter basicity, sinter productivity and reduction degradation index (RDI) decreased and tumbler index (TI) increased for both low and high alumina sinter at coke breeze rate of 65 kg t−1 of sinter. The low alumina sinter showed higher productivity and strength, and lower RDI due to the presence of higher silico ferrites of calcium and aluminium (SFCA) and magnetite phase, and lower pore phase as compared to high alumina iron ore sinter. The sinter productivity decreased and physical and metallurgical properties improved with increase in coke breeze addition by increasing the sinter basicity for high alumina sinter.