Sinter Plant Research Articles

Resource and energy saving technologies of refractory linings of thermal units

In Russian practice, the vast majority of thermal units and other industrial furnaces are still built with the use of single-piece ceramic refractories. The purpose of research was to develop a wide range of special materials suitable for repairs of any linings of thermal units. In accordance with the purpose, this paper solved the following tasks: Selecting reactive binders used in the compositions of refractory concrete capable of structural modification of any refractory lining materials; Developing impregnating-coating compositions based on reactive binders capable of forming a protective coating with high adhesive strengthen linings; Developing compositions of refractory ramming mixtures, used for the repair of large fragments of linings and having high adhesion to any refractory lining materials; Checking the effectiveness of the technology in production environment. In this paper, we used not only standard techniques but also specially designed ones, in particular, to determine the adhesion of refractory coating to the refractory lining materials. The technology of repair works consists of application of some or all of the above solutions depending on the state of worn out lining of the thermal unit. Testing was carried out on many sintering plants of Samara region where rotary kilns are operated. The use of such chemically active substances as phosphate bonds and sodium silicate solutes in special refractory repair compositions with different functional purpose, allowed increasing the durability of liners of expanded fire clay rotary kilns as a result of reparatory works. Some items from the general technological scheme of repair works to restore the linings of heating units may be used in industrial furnaces in many industries.

Dioxin emission from some metallurgical processes

Results of the measurements of emissions of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in two metallurgical plants representing ferrous metallurgy (an iron ore sintering plant) and non-ferrous metallurgy (a secondary copper smelter) are discussed in the paper. In the case of the secondary copper smelter dioxin concentrations were determined in the range from 0.03 to 8.1 ng TEQ/Nm3 and high variability of emissions was observed, which did not depend on the composition of material fed and the stage of smelting. In the case of measurements carried out in the iron ore sintering plant the concentrations ranged from 0.6 to 1.7 ng TEQ/Nm3. It was found additionally that a well-functioning electrostatic precipitator could reduce PCDD/Fs emissions even by 75% (with respect to the total mass of congeners), while off-gas recirculation had no significant effect on the emissions. The paper contains original results of dioxin emission measurements from a secondary copper smelter plant and an iron ore sintering plant in Poland. In the first plant, high variability of flue gas flow and concentrations of dioxins between successive batches as well as within a single smelting process was found. This problem has never been described in the literature. In the second plant, great stability of dioxin emissions from the iron ore sintering plant and high emission reduction efficiency (about 70%) of dioxins by an electrostatic precipitator were observed. No significant effect of gas recirculation on the PCDD/Fs emission was reported.

Dioxin emission from some metallurgical processes

Results of the measurements of emissions of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in two metallurgical plants representing ferrous metallurgy (an iron ore sintering plant) and non-ferrous metallurgy (a secondary copper smelter) are discussed in the paper. In the case of the secondary copper smelter dioxin concentrations were determined in the range from 0.03 to 8.1 ng TEQ/Nm3 and high variability of emissions was observed, which did not depend on the composition of material fed and the stage of smelting. In the case of measurements carried out in the iron ore sintering plant the concentrations ranged from 0.6 to 1.7 ng TEQ/Nm3. It was found additionally that a well-functioning electrostatic precipitator could reduce PCDD/Fs emissions even by 75% (with respect to the total mass of congeners), while off-gas recirculation had no significant effect on the emissions. The paper contains original results of dioxin emission measurements from a secondary copper smelter plant and an iron ore sintering plant in Poland. In the first plant, high variability of flue gas flow and concentrations of dioxins between successive batches as well as within a single smelting process was found. This problem has never been described in the literature. In the second plant, great stability of dioxin emissions from the iron ore sintering plant and high emission reduction efficiency (about 70%) of dioxins by an electrostatic precipitator were observed. No significant effect of gas recirculation on the PCDD/Fs emission was reported.

Using Mathematical Simulation to Evaluate the Efficiency of Iron Ore–Coal Brexes in Blast-Furnace Smelting

A mathematical model of the blast-furnace process developed by the MISiS is used to analyze the efficiency of a charge containing, in equal portions, coal-containing brexes made of iron-ore concentrate, superfluxed sinter, and non-fluxed oxidized pellets. Mathematical simulation shows that replacing 50% of sinter production by clean brex production will reduce the coke consumption by at least 10% and the dust and gas emissions of sintering plants by 50%.

The Functional Resonance Analysis Method for a systemic risk based environmental auditing in a sinter plant: A semi-quantitative approach

Environmental auditing is a main issue for any production plant and assessing environmental performance is crucial to identify risks factors. The complexity of current plants arises from interactions among technological, human and organizational system components, which are often transient and not easily detectable. The auditing thus requires a systemic perspective, rather than focusing on individual behaviors, as emerged in recent research in the safety domain for socio-technical systems. We explore the significance of modeling the interactions of system components in everyday work, by the application of a recent systemic method, i.e. the Functional Resonance Analysis Method (FRAM), in order to define dynamically the system structure. We present also an innovative evolution of traditional FRAM following a semi-quantitative approach based on Monte Carlo simulation. This paper represents the first contribution related to the application of FRAM in the environmental context, moreover considering a consistent evolution based on Monte Carlo simulation. The case study of an environmental risk auditing in a sinter plant validates the research, showing the benefits in terms of identifying potential critical activities, related mitigating actions and comprehensive environmental monitoring indicators.

Atmospheric occurrence and health risks of PCDD/Fs, polychlorinated biphenyls, and polychlorinated naphthalenes by air inhalation in metallurgical plants.

Metallurgical plants are important sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs). It is significant to evaluate the air levels and human risks of PCDD/Fs, PCBs and PCNs in metallurgical plants considering their adverse effects on human health and thousands of metallurgical plants being in operation in China. The estimated inhalation intakes of PCDD/Fs, PCBs, and PCNs together in eight iron ore sintering plants, three secondary copper plants, four secondary aluminum plants, and one secondary lead plant were 4.9-213.4, 21.4-4026.4, 28.7-630, and 11.7fgTEQkg-1day-1, respectively, and the corresponding cancer risks were estimated to be 8.7×10-7 to 3.8×10-5, 5.1×10-6 to 1.1×10-4, 3.8×10-6 to 7.1×10-4, and 2.1×10-6, respectively. The estimated cancer risk were higher than 100 per million people for three secondary aluminum and copper smelters among the sixteen metallurgical plants, indicating high cancer risks. Stack gas samples from metallurgical plants were also collected and analyzed for comparing their emission profiles with that of air samples. The comparison of PCDD/F, PCB and PCN profiles between air samples and stack gas samples by similarity calculation and principal component analysis suggested the influence of stack gas emissions from metallurgical plants on surrounding air. These results are helpful for understanding the exposure risk to PCDD/Fs, PCBs and PCNs in numerous metallurgical plants being operation in China.

Optimization of By-Products Reuse in the Steel Industry: Valorization of Secondary Resources with a Particular Attention on Their Pelletization

An improvement of by-products reuse contributes to reduce the environmental impact of industries and to increase their competitiveness. Within the steel production cycle, several by-products are produced: slags, sludges, scales, dusts. Some of them are directly suitable to the internal reuse, other ones can be separated in fractions that can be used internally or sold for external use. This paper shows an analysis focused on the optimization of by-products reuse in an Italian Integrated Steelworks with a particular attention on the internal recycling in the pelletization process. Starting from previous studies on the selection of suitable by-products and treatments, the paper presents, firstly, the development of a superstructure model using reMIND® software in order to find optimal solutions, considering quality and environmental constraints, and to minimize operating costs. Furthermore, the evaluation and the optimization through laboratory or simulation tests of possible mixtures of by-products to be used in pelletization is also discussed. By-product mixtures were evaluated to the aim of achieving good pellets formation, according to the number, size of pellets and the compression test results. This study shows that a particular scenario is capable to jointly reduce costs and environmental impact as well as to obtain high quality pellets that can maximize the internal reuse in sinter plant of by-products in a particular” winning formula” (BOF slag 65 wt%, BOF sludge 27 wt%, dolime 1 wt%, cement 7 wt%). These preliminary results show that a good by-products management could provide important advantages to the companies by contributing to the “zero waste” target.

Tracking the Historical Traces of Soil Pollution from an Iron-Sintering Plant by Using Magnetic Susceptibility in Wawa, Ontario, Canada

This study evaluates the present day effects of air pollutants emitted from an iron sintering plant near Wawa (Ontario, Canada) decades ago (1939–1998). During smelting and refining of iron ore, gaseous sulfur-rich emissions and large amounts of metal-containing (iron oxides) particulate materials were released in to the air, and eventually settled onto vegetation and soil cover. We test the feasibility of using magnetic measurements to investigate and quantify the soil pollution resulting from the sintering plant. Surface and subsurface magnetic susceptibility measurements, as well as various magnetic mineral properties, have been collected in a scheme designed to mimic the previously determined pollutant contamination zones. A total of 50 sites were sampled (with a sampling grid of 250 m) within and around the smelter kill zone to the northwest of Wawa. Results were plotted on cross sections perpendicular (X-X′) and parallel (Y-Y′) to the dominant wind direction in order to investigate magnetic properties of the soil samples as a function of both wind direction and distance from the source. Samples located in Rao and LeBlanc’s (The Bryologist 70:141–17, 1967) pollution zones 1 and 2 typically have κin-situ values >120 × 10−5 SI, while the zone 3 and 4 results are <100 × 10−5 SI. Magnetic susceptibility enhancements at depths of 5–10 cm were found to be related to the presence of magnetic spherules (fly-ashes) at sites on the wind-parallel Y-Y′ profile in the previously defined kill zone. An estimated minimum migration rate of iron-rich particulates is calculated for coarse sand and silt/clay sites as 0.24 and 0.1 cm/year, respectively.

A pilot-scale study of selective desulfurization via urea addition in iron ore sintering

The iron ore sintering process is the main source of SO2 emissions in the iron and steel industry. In our previous research, we proposed a novel technology for reducing SO2 emissions in the flue gas in the iron ore sintering process by adding urea at a given distance from the sintering grate bar. In this paper, a pilot-scale experiment was carried out in a commercial sintering plant. The results showed that, compared to the SO2 concentration in flue gas without urea addition, the SO2 concentration decreased substantially from 694.2 to 108.0 mg/m3 when 0.10wt% urea was added. NH3 decomposed by urea reacted with SO2 to produce (NH4)2SO4, decreasing the SO2 concentration in the flue gas.

Reliability Target Assessment Based on Integrated Factors Method (IFM): A Real Case Study of a Sintering Plant

The success of a company depends on customer’s satisfaction: quality, price, and service. These three goals depend in particular on R.A.M.S. characteristics: reliability, availability, maintainability, and safety. In the last few years, in order to guarantee high standards of reliability and maintainability, new methodologies and techniques have been developed to estimate the R.A.M.S. targets. In particular, the reliability target represents both the starting and the ending point of R.A.M.S. analysis. The design of the reliability target of a system is a crucial aspect of reliability analysis, as it affects the performance of the system and components. This paper aims to develop a new approach called “IFM Target,” to define the reliability target for complex systems through the integrated factors method, to combine the advantages of usually used approaches, and to overcome some criticalities highlighted in a careful literature analysis. The proposed method has been applied on a sintering system. The results show the effectiveness of the proposed approach.

Effects of slurry properties on simultaneous removal of SO2 and NO by ammonia-Fe(II)EDTA absorption in sintering plants

Simultaneous removal of SO2 and NO by ammonia-Fe(II)EDTA absorption has become a research focus in recent years. In order to get useful data for further industrialization, in this work the practical operating conditions of the sintering plant were simulated in a pilot-scale reactor in order to explore the effects of slurry properties on simultaneous removal of SO2 and NO. It was not conducive to the absorption of NO when (NH4)2SO4 concentration and slurry temperature had been increased. The initial NO removal efficiency decreased from 90.63% to 44.12% as the (NH4)2SO4 concentration increased from zero to 3.5 mol/L. With the increasing of Fe(II)EDTA concentration, SO32− concentration and pH value of absorption liquid and the absorption capacity of NO by Fe(II)EDTA solution increased. Especially the existence of SO32− ions in slurry had significantly improved the service life of chelating agents. The NO removal efficiency only decreased by 16.46% with the SO32− concentration of 0.3 mol/L after 30-min of operation. The chloride ions had no effects on the absorption of SO2 and NO. The results indicated that changes of slurry properties had different effects on simultaneous removal of SO2 and NO by ammonia-Fe(II)EDTA solution. The basic data offered by the experiments could effectively contribute to further industrial applications.

Efficiency Improvement of Sintering as a Result of Surface-Active Substance Use in Pelletizing at the JSC "Ural Steel"

A set of pilot experiments to improve pelletizing through the use of the sinter charge humidification of water-soluble organic surface-active agents (surfactants) has been performed in the sintering plant JSC "Ural Steel". It has been found that the surfactant use provides an improved granularity of the sinter charge and increases its gas permeability during sintering that ensures a better technology and quality. The maximum efficiency from the surfactant use is manifested in the area of the optimum moisture content of the sinter charge (7 – 8 %) at a flow rate of the experimental binder 1.2-1.6 l/h (surfactant concentration in an aqueous solution is 0.3 – 0.4 ml/l).

Development and characterization of epoxy-based composites filled with Linz–Donawitz sludge

Integrated steel plants in general produce large amounts of solid wastes during iron and steel making process. LD sludge or Linz–Donawitz sludge (LDS) are the fine solid particles recovered after wet cleaning of the gas emerging from LD convertors during steel making. In general 8 kg Linz–Donawitz sludge is generated per one ton of crude steel production. This solid waste can have many valuable product-oriented applications if processed economically. The common reuse methods for Linz–Donawitz sludge are recovery of metal values, recycling in sinter plant, and production of value-added products. But its use as filler in polymer composites is not yet established. This work includes the processing and characterization study of epoxy resin filled with micro-sized Linz–Donawitz sludge. Mechanical properties of the composites are evaluated under standard test conditions. Sliding wear tests are conducted using Taguchi’s L25 orthogonal arrays over a range of sliding velocities (36–315 cm/s), normal loads (5–25 N), sliding distances (500–2500 m), and Linz–Donawitz sludge contents (0–20 wt.%). A theoretical model is developed to estimate the wear rate of these composites under different test conditions. The results obtained from the proposed theoretical model are found to be in good agreement with the experimental values under similar test conditions. Taguchi’s analysis suggests that the composition of the composite and the sliding velocity are the most significant factors affecting the specific wear rate. This study further reveals that wear resistance of neat epoxy is enhanced by incorporation of micro-sized LD sludge particles.

Failure Analysis of Wear Block of Crush Deck Used in Sinter Plant

Failure analysis of wear block used in the crush deck of a Sinter Plant was carried out. Crush deck acts as a platform to transfer the hot sinter cake from sinter machine to crushing unit. Hot sinter cake with a temperature around 800 °C falls on the crush deck from the discharging end of rotating sinter machine. This investigation consists of visual observation, chemical analysis, characterization of microstructures, energy dispersive spectroscopy, and measurement of hardness. Analysis revealed that this is an iron-based material with Cr–Ni alloying with higher hardness and lower toughness, which was due to improper microstructure. Microstructure revealed a large number of primary carbides along with needle-shaped carbides, which drastically reduce the toughness of the material. Application point of view the wear block should have optimum combination of toughness and wear resistance at elevated temperature; however, analyses showed the actual wear block had with higher wear resistance and lower toughness. This was reflected in the undesirable microstructure observed during metallographic study. It was thus concluded that the component failed before a proper life cycle was achieved due to poor material properties. Based on the failure analysis suitable heat treatment process was recommended. Metallurgical study carried out on the suggested material, showed significant improvements in material property. Trial of recommended wear block was taken at the plant level and life of the recommended material improved twice than that of previous one.

Recent advances in iron ore sintering

Sintering is the most economic and widely used agglomeration process to prepare iron ore fines for blast furnace use. Owing to the depleting reserves of traditional high grade iron ore, there have been considerable changes in iron ore resources available throughout the world, especially in steel mills in East Asia. Corresponding to the changes in the availability of iron ore resources, the amount of impurities in iron ore has been slowly increasing. Some of these impurities have been found to have deleterious impacts on sinter quality and sintering performance. In the meantime, an increasing number of large blast furnaces with inner volumes of more than 5000 m3 have been built in East Asia which require more sinter and are often more demanding in terms of the quality requirements of the ferrous materials. Finally, sinter plants are facing increasing pressure due to more stringent regulations regarding their environmental impact. This paper gives an overall review of a variety of technologies developed worldwide to tackle the changing raw material characteristics and mitigate emissions from sintering operations. Given the high sinter usage and volume of their blast furnaces, most of the recent sintering technologies have originated from East Asia, particularly Japan.

Optimization of Sinter Plant Operating Conditions Using Advanced Multivariate Statistics: Intelligent Data Processing

Blast furnace operators expect to get sinter with homogenous and regular properties (chemical and mechanical), necessary to ensure regular blast furnace operation. Blends for sintering also include several iron by-products and other wastes that are obtained in different processes inside the steelworks. Due to their source, the availability of such materials is not always consistent, but their total production should be consumed in the sintering process, to both save money and recycle wastes. The main scope of this paper is to obtain the least expensive iron ore blend for the sintering process, which will provide suitable chemical and mechanical features for the homogeneous and regular operation of the blast furnace. The systematic use of statistical tools was employed to analyze historical data, including linear and partial correlations applied to the data and fuzzy clustering based on the Sugeno Fuzzy Inference System to establish relationships among the available variables.

Concentrations of and health risks posed by polychlorinated dibenzo-p-dioxins and dibenzofurans around industrial sites in Hebei Province, China

Sintering and steel production as the main emission sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) may affect environment and human health. The concentrations, profiles, and distributions of PCDD/Fs in soil samples from around four typical sintering and steel production plants in Hebei Province, China, were determined. Forty-six soil samples were collected at distances from 500 to 9000m from industrial plant chimneys. The concentrations of total 17 2,3,7,8-substituted PCDD/F congeners in the soil samples from sites A, B, C, and D were in the range 11-130, 13-284, 2.6-378, and 21-231pg/g, respectively, and the internationally accepted toxic equivalent (I-TEQ) concentrations were 0.37-13.2, 0.31-12.1, 0.13-13.7, and 1.60-22.7pg I-TEQ/g, respectively. Soil ingestion was estimated the major exposure pathway to PCDD/Fs. At current PCDD/F concentrations, the local population will be exposed to low amounts of PCDD/Fs in soil from around the industrial sites, and this exposure will pose potential health risks for the local population living at distances of less than 1000m from nearest stack but will have no high health risks for people living further away. These results will be helpful when planning measures to control PCDD/F sources. The data will also benefit local environmental monitoring studies and be useful when assessing the risks posed by PCDD/Fs around the industrial sites to the environment and humans.

The physiochemical properties of submicron particles from emissions of industrial furnace

Purpose Smoke and dust emissions from industrial furnaces can do great harm to the environment and human health. This paper aims to analyze the morphology, diameter and elements of the submicron particles from the furnace flues and the nearby ambient air by using two typical industrial furnaces, the sintering furnace and the electric furnace. Design/Methodology/Approach Two typical industrial furnaces, the sintering furnace and the electric furnace, were chosen in this study, to analyze the morphology, diameter and elements of the submicron particles from the furnace flues and the near-by ambient air. Findings The results show that the particles from the two furnaces are mainly in the small sizes of 0.3-0.6 μm. Particles from sintering plant flue are mainly spherical and rich in K and Cl, whereas those from the electric plant flue are mainly particles rich in metal elements, such as Zn and Fe, and have different morphology. Originality/value The particles in the atmosphere nearby the two furnaces contain aged particles from the flue, lots of spherical particles, rectangle particles and various aggregations. The elements of those particles are complex.

Effects of sintering flue gas properties on simultaneous removal of SO2 and NO by ammonia-Fe(II)EDTA absorption

The simultaneous removal of SO2 and NO from sintering flue gases can be realized by ammonia-Fe(II)EDTA absorption, which has become a hotspot for research. In order to get useful data for further industrialization, the practical operating conditions of the sintering plant were simulated and the experiments were performed to explore the effects of sintering flue gas flow rate, flue gas temperature, compulsory oxidation, SO2 and NO concentrations on the combined elimination of SO2 and NO in a pilot-scale reactor. According to the experimental results, it was not conducive to the absorption of NO when the flue gas flow rate, the oxidation air flow rate and the NO concentration increased. The impact of flue gas temperature on the removal of SO2 and NO was not obvious when the slurry temperature was constant. In addition, the SO2 concentration had little effect on the absorption of SO2 and NO.

Mono- to Octachlorinated Polychlorinated Dibenzo-p-dioxin and Dibenzofuran Emissions from Sintering Plants Synergistically Controlled by the Desulfurization Process.

The influence of desulfurization systems in sintering plants on polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/F) concentrations, profiles, and emission factors was studied. Mono- to tri-CDD/Fs and tetra- to octa-CDD/F concentrations were 4.4 ± 2.3 and 10.5 ± 8.3 ng m(-3), respectively, at the inlets and 0.87 ± 0.48 and 0.47 ± 0.22 ng m(-3), respectively, after desulfurization. The toxic equivalents (TEQs) were 0.95 ± 0.093 and 0.51 ± 0.040 ng of I-TEQ m(-3) at the inlets and after desulfurization, respectively. The congener profiles and homologue distributions were dominated by 2-MoCDF and MoCDF, respectively. The PCDD/F removal efficiencies achieved by desulfurization increased as the chlorination level increased. The PCDD/Fs became adsorbed to gypsum. Annual mono- to tri-CDD/Fs PCDD/F and TEQ (tetra- to octa-CDD/F) emission factors for flue gas and gypsum between 2003 and 2012 were determined. The total amounts of mono- to tri-CDD/Fs emitted in flue gas and gypsum between 2003 and 2012 were 10.7 and 10.2 kg, respectively. The total TEQs emitted in flue gas and gypsum between 2003 and 2012 were estimated to be 15486 and 1878 g of I-TEQ, respectively. PCDD/Fs adsorbed to gypsum are not effectively eliminated. The PCDD/F concentrations increased as the fly ash surface area increased moving through the electrostatic precipitator stages.