Sinter Plant Research Articles

SCORN: Sinter Composition Optimization with Regressive Convolutional Neural Network

Sinter composition optimization is an important process of iron and steel companies. To increase companies’ profits, they often rely on innovative technology or the workers’ operating experience to improve final productions. However, the former is costly because of patents, and the latter is error-prone. In addition, traditional linear programming optimization methods of sinter compositions are inefficient in the face of large-scale problems and complex nonlinear problems. In this paper, we are the first to propose a regressive convolutional neural network (RCNN) approach for the sinter composition optimization (SCORN). Our SCORN is a single input and multiple outputs regression model. Sinter plant production is used as the input of the SCORN model, and the outputs are the optimized sintering compositions. The SCORN model can predict the optimal sintering compositions to reduce the input of raw materials consumption to save costs and increase profits. By constructing a new neural network structure, the RCNN model is trained to increase its feature extraction capability for sintering production. The SCORN model has a better performance compared with several regressive approaches. The practical application of this predictive model can not only formulate corresponding production plans without feeding materials but also give better input parameters of sintered raw materials during the sintering process.

Influence of biocoke on iron ore sintering performance and strength properties of sinter

Purpose. The research purpose is to substantiate the use of biocoke as a fuel in the iron ore sintering, as well as its influence on the performance and properties of the resulting sinter. To completely replace conventional coke breeze, biocoke is produced using 5 wt.% biomass wood pellets at different carbonization temperatures of 950 or 1100°C. Further, the influence of biocoke on the sintering process and the sinter quality is studied at a high proportion of biomass pellets of 10, 15, 30, 45 wt.% and a carbonization temperature of 950°C. Methods. Carbonization is performed in shaft-type electric furnaces to produce laboratory coke or biocoke. Afterward, the sintering of iron ores is conducted on a sinter plant. To assess the sintering process and the quality of the resulting sinter, the filtration rate is determined on a laboratory sinter plant using a vane anemometer designed to measure the directional flow average velocity under industrial conditions. The sinter reducibility is studied using a vertical heating furnace to assess the effect of coke and biocoke on the sinter’s physical-chemical properties. Findings. It has been determined that biocoke, carbonized at a temperature of 950°C, has good prospects and potential for a shift to a sustainable process of iron ore sintering. Originality. It has been proven that biocoke with a biomass pellet ratio of up to 15 wt.%, obtained at a temperature of 950°C, does not affect the parameters characterizing the sintering process. The sinter strength indicators correspond to the use of 100 wt.% conventional coke breeze. Biocoke used with a high proportion of biomass pellets of 30 and 45 wt.% causes a deterioration in the sinter quality. Practical implications. The results of using biocoke with the addition of 5-15 wt.% biomass pellets and at a temperature of 950°C are within the standard deviation, which makes it possible to use biocoke with 15 wt.% biomass pellets instead of industrial coke breeze.

THE USE OF SOIL MICROORGANISMS AND HIGHER PLANTS IN THE NEUTRALIZATION OF INDUSTRIAL WASTE IN THE METALLURGICAL, ENERGY AND COAL MINING INDUSTRIES

The self-overgrowth of industrial dumps and tailings of waste from the metallurgical enterprises, energy facilities and coal mining industry is impossible due to the high phytotoxicity of the stored waste. They are dangerous sources of environmental pollution and negative impact on public health. The results of the field experiments on the biological reclamation of the tailings of the Abagur sinter plant, the Baidayevsky coal mine and the Tom-Usinsk State District Power Plant, where the poplar clones obtained from the Botanical Garden of the Siberian Branch of the Russian Academy of Sciences (Novosibirsk), a legume-grass mixture of perennial grasses consisting of hybrid clover and awnless rump served as a plant material. As a soil improver, the wastewater (wastewater sludge WWS) from treatment plants of the city of Novokuznetsk were used. The microbiological fertilizer “BakSib” containing spore-forming bacteria served as a source of the soil microorganisms. The combined use of WWS and the bacterial preparation “BakSib” showed high efficiency in ensuring the survival rate of the cloned poplars, which varied from 70 to 90%. It has been established that the use of bacterial preparations and WWS for the reclamation of technogenically disturbed territories reduces the adverse impact of limiting environmental factors by increasing the water supply and introducing nutritional components into the surface root layer of poplars, hybrid clover and awnless brome. In the reclaimed areas, the moisture content of the substrate was recorded from 5.1 to 14.7%, while the moisture index was 13%.

Real-time dynamic prediction model of carbon efficiency with working condition identification in sintering process

Accurate prediction of carbon efficiency is a prerequisite for achieving energy saving and consumption reduction in an iron ore sintering process, and is the key to guaranteeing the quality and yield of sintered ore. This paper proposes an original real-time dynamic prediction model for carbon efficiency prediction in the process. A Savitzky–Golay filter is used to eliminate noise of the actual production data collected from a cooperative sintering plant, and the correlation between carbon efficiency and process parameters is determined by mutual information. A modified version of maximum entropy clustering algorithm is presented for identifying working conditions to accurately discriminate between anomalies and normal working conditions. Then, the real-time dynamic prediction model of carbon efficiency based on broad learning is established by taking into account the process characteristics and using the prediction error information under normal working conditions. The proposed model is demonstrated to be valid by carrying out some experiments with actual production data. The experimental comparative analysis show that this model has good generalization capabilities and high real-time prediction accuracy, and is superior to other advanced methods in dynamic prediction of carbon efficiency.

Model of an iron ore sinter plant with selective waste gas recirculation

The use of sinter influences hot metal production substantially and significantly affects an integrated steel mill’s total emissions. Sintering of iron ores is an enormous energy-intensive and resources consuming process. Introducing a selective waste gas recirculation (SWGR) to the sintering process reduces the energy consumption, stack gas volume flow, and sulfur dioxide emissions of an iron sinter production. Simulating this complex process in flowsheet simulations of integrated iron and steelworks is a fast and cost-effective opportunity to validate new operation settings. The implementation of a sinter plant in gPROMS ModelBuilder®characterizes the sintering processes by three main sub-models. A burner model describes the gas combustion, a black-box model consider the main sintering processes, and a wind box model divides the total off-gas into a recycle gas and a stack gas. A specific temperature polynomial represents the temperature distribution across the wind boxes to allow detailed investigations on SWGR in complex flowsheet simulations. Implementing SWGR to the sintering process, the model shows a reduction of coke consumption, stack gas flow rate, and sulfur dioxide emissions by 11%, 27%, and 27%, respectively. In the SWGR scenario, the utilization rate of carbon monoxide increases and less coke is consumed. The chlorine emissions of the sintering process differ with and without SWGR insignificantly.

Atmospheric PM2.5 near an Urban-Industrial Complex during Air-pollution Episodes with Various Meteorological Conditions

This study investigates the atmospheric fine particulate matter (PM2.5) issue caused by the multi-effect of complicated sources, terrain, and meteorology at Southern Taiwan. Three sampling stations represent an urban, a rural, and a coastal sites near an urban-industrial complex. The atmospheric PM2.5 were measured during a pollution episode from November to February, when the reference samples were collected in April. The sample was collected with a constant-flow sampler with the Federal Reference Method performance. After determining the PM2.5 mass, their chemical compositions of ions, metals, and carbons were analyzed for the different properties caused by the multi-factors. The chemical mass balance (CMB) model was employed to evaluate the emission contributions. Additionally, an inverse trajectory model is used to analyze the pollutant transport and support the CMB results. The air-pollution episodes occurred within the winter to spring. The PM2.5 were composed of 51-69% ions, 18-31% carbonaceous species, and 1.5-3.0% metals. The SO42-, NH4+ and NO3- contributed 92-96% of the ions. Most of the organic/elemental carbon ratios were low, suggesting more primary carbon emissions. The metal contents were minor and dominated by Fe and Zn. The CMB model indicated the PM2.5 were dominated by 24% secondary SO42-, 14.7% traffics, 8.3% petrochemical emissions, 6.8% soil dust, and 4.5% sintering plant emission. For non-episode days, the PM2.5 were contributed by 34.9% traffics, 30% the secondary SO42-, 10.3% secondary NO3- , and 6.8% soil dust. Nevertheless, the frequent sea-land breeze might lead to more powerful wind eddies and bring the primary PM2.5 and the aerosol precursors from the emission areas. Consequently, the uncontrollable meteorological changings would lead to the pollution issues at the lowly convective area. Therefore, the averaging emissions of the PM2.5 and precursors should be lowered; meanwhile, the rapid controls of the primary emissions are suggested when the high-level PM2.5 are forecasted.

Analysis and prediction of sinter yield and strength based on mathematical programming model

This article proposes a method for a comprehensive analysis of the controlled parameters of the technological process and the dynamics of sinter cake disintegration during mechanical processing, taking into account the transport lag of the measured output characteristics (fines yield 0-5 mm when sinter cake is destroyed within the sinter plant and along the conveyor path for transporting sinter to the blast furnace shop) from the current composition of the charge and the parameters of the sintering process. On the basis of the specified output characteristics, an assessment of the sinter yield and strength was carried out. To analyze and predict the physical and mechanical properties of iron ore sinter, a new method of constructing regression equations based on linear programming problems with partially Boolean variables was used. The most significant drawback of the standard approach is the strong dependence of the regression equation coefficients on random anomalous observations (outliers), which in practical problems can be quite large and it is impossible to filter them out. The proposed MILP Regression method improves the forecast quality by automatically excluding atypical observations from consideration. The method is compared with other regression models. The method of mixed integer linear programming (MLIP) was used to process the current information about the operation of the sinter shop No. 3. The most significant parameters that affect the formation of the total amount of fines during the destruction of sinter were established: the component composition of the charge, sinter machine pallets speed, pressure gas and temperature in collectors, temperature in ignition furnaces and behind them, temperature in last vacuum chambers of sintering machines. The obtained regression equations quite accurately reflect the influence of the initial data array on the yield of recycled sintering products and they can be used to predict the output parameters of the sinter quality. A. A. Eliseev, manager on raw materials research (PJSC Severstal), Yu. A. Malygin, director (JSC Ferroks), N. P. Chernavin, assistant of the department “Big data analytics and video analysis methods” (Ural federal university), F. P. Chernavin, associate professor, department “Simulation of managing systems” (Ural federal university) participated in preparation of this article.

Physical and chemical characterization of fugitive particulate matter emissions of the iron and steel industry

The iron and steel industry is a notable particulate matter emitter. In source apportionment of particulate matter, it is important to identify the characteristics of particulate matter originating from steel sites. However, previous studies mostly focus on stack emission sources, while few reports on fugitive emission sources are available. Aiming to fill this gap, the physical and chemical characteristics of fugitive emission sources in the whole iron and steel production process were explored. The emission factor, particle size distribution (PSD), and morphological and chemical profiles of fugitive particulate matter (FPM) originating from fugitive emission sources at the observed site were analyzed through on-site sampling and in-lab testing. The emission factors in descending sequence are those of steelmaking plants, sinter plants, ironmaking plants and coking plants. The particle size of FPM mainly ranges from 0.1 to 716 μm, while distribution forms with both unimodal and bimodal peaks occur. The microscopic morphology of FPM is mainly divided into: irregular Fe-, Si-, Ca- and Mg-rich mineral particles formed by physical means, layered carbonaceous particles formed by mechanical crushing and combustion cracking, spherical Si-, Al- and Fe-rich particles in a high-temperature molten state, and chain and agglomerate particles formed by the polymerization of high-temperature flue gas and volatile minerals. The mass fraction of Fe ranks first in the sintering, ironmaking, and steelmaking processes, with values ranging from 1.40% to 57.79%. C attains the highest mass fraction, 69.80%, in the PFM originating from crushing mills.

New insights into the effects of methane and oxygen on heat/mass transfer in reactive porous media

The partial replacement of a hydrogen-based gaseous fuel for solid fossil fuel plays a key role in increasing the sustainable energy share in sinter plants. The imbalanced heat distribution is a long-standing problem that can adversely affect the energy efficiency of sintering process, especially in the near-inlet region. In the present study, the impacts of methane and oxygen injection concentrations on sintering performance were numerically examined. Compared with previous studies, the maximum methane concentration examined was extended significantly from 1.0% to 5.5%, which is very close to the lean flammable limit (5.3%). Computations demonstrated that methane concentration had considerable effects on the methane combustion dynamics and solid fuel oxidation. In the near-inlet region, injecting methane at a high concentration (3.5%) remarkably expanded the melting zone and increased the melting quantity index. In addition, the results indicated that reacting flow with a low oxygen concentration could decrease the melting zone propagation speed in the near-inlet region, thereby improving the local sintering performance. However, the reacting flow with high methane concentration and low oxygen concentration had negative impacts on the sintering speed. The recommended operating conditions were determined based on parametric studies to achieve a tradeoff between the sinter quality and productivity.

CONFORMITIES TO LAW OF FORMING LAYER FOR POLYDISPERSE PELLET CHARGE ON SINTER BELT

Motion of pellet charge on the loading tray on a sinter belt is accompanied not only by the change of its grain-size composition, but by segregation processes, id est. by the redistribution of charge of different size particles for the most part friable material. The result of this process is formation of local discontinuity with pre-dominance of content for particles of certain factions. The traditional method for analysis of work for loading tray on the basis of factious classification does not allow to educe and analyze appearing heterogeneity in the most part friable material. It results in errors at the calculation for action of the system of the automated control by sintering process and ignoring of notational of the use of segregation of particles of friable material for optimization of technological process. The use of balance method enables to specify and spread understanding of mechanism of processes which take place during motion of pellet charge in relation to the loading tray, and also to form theoretical pre-conditions for the choice of the rational modes of operations of agglomeration separation of sintering plant. It is set that at monotonous increase of angle of slope for loading tray the segregation phenomena increase in a pellet charge, and after achievement of the defined value – go down, id est. have extreme character. Mentioned features of forming of layer for polydisperse material in the conditions of inconstancy of mechanical properties of its separate factions it is possible to take into account at the use of balance of grain-size composition of charge, loaded on a sinter belt, and charge, being on it, when conditional middle diameters of particles of their components must be equal. On the basis of the set conformities to law of forming of friable of structure of layer the method of authentication of grain-size compositions of pellet charge mixture is in theory reasonable in every its horizon taking into account a segregation during loading.

SINTER PLANT WASTE HEAT RECOVERY PROCESS AND ITS BENEFIT IN INDIAN STEEL INDUSTRY

Sinter waste heat recovery system is a process onwards gainfully utilization of untapped waste heat from sinter plant for generating steam either for process steam requirement or in turn can produce power for plant. The saving in power will reduce the cost of production of sinter and in turn, the cost of steel. Sinter waste heat recovery is a very promising option for the future adoption in Indian steel industry. The current statuses of this technology in various countries are also under adoption. Finally, the potential of implementation in Indian steel has been discussed and its challenges as well as opportunities involved.

MEROS Dust Quality of Different Plants and Its Potential Further Uses

Sintering is a process of agglomeration of fine particles into porous sinters for blast furnaces. During the sintering process, high volumes of sinter plant gas containing high loads of dust, SO2 and NOX and toxic pollutants, such as heavy metals (e.g., Hg, Pb, Cr and Cd) and PCDD/F, are emitted. The objective of this study was to characterize dusts of different plants as the basis for suggestions of reutilization and treatment options. Dusts, eluates and residues were produced and DOC, T-N, ions and heavy metals were analyzed. The results show that dusts from different plants are very similar in terms of DOC, T-N, Mg, Ca and many heavy metals and only differ in criteria such as suspended solids and ions such as K, Na, Cl and SO4. Based on the high levels of alkalis and low levels of iron, direct recycling into the sinter or furnace process is not recommended. The dissolution of the soluble substances in water reduces the MEROS dust by 90% of the weight and extracts the alkalis. The remaining wastewater needs to be treated to reduce DOC, T-N and some heavy metals. The solid residues can be recycled into the sinter to reduce potential PCDD/F, which are attached to the activated carbon.

Study on Sintering Characteristics of Ultra-Poor Vanadium-Titanium Magnetite

Artificial rich ore for blast furnace use can be produced by sintering ultra-poor vanadium-titanium magnetite (PVTM) with a high-grade iron concentrate. Here, acid (R = 0.33, 0.50), self-fluxing (R = 1.10), and high-basicity (R = 2.60) PVTM sinters were produced in a sinter pot. Their performances were determined using the comprehensive index. The microstructures of the PVTM sinter were observed by metallographic microscope and scanning electron microscopy equipped with an energy dispersion spectrum (SEM-EDS). The results suggest that the acid PVTM sinter had a low flame front speed, low productivity, an uneven size distribution, and poor softening properties. It did have a high tumble index (TI) and low-temperature reduction disintegration index (RDI). The self-fluxing PVTM sinter had the worst performance (TI, RDI, reducibility index (RI)), while the high-basicity PVTM sinter had the highest flame front speed, highest productivity, a reasonable size distribution, excellent softening properties, and satisfactory TI and RDI values. The main consolidation form of the acid sinter was crystal stock, the main bonding phase of the self-fluxing sinter was silicate, and the main bonding phase of the high-basicity sinter was silico-ferrite of calcium and aluminum (SFCA). The comprehensive index values (from high to low) were the high-basicity (R = 2.60), acid (R = 0.50), natural acid (R = 0.33), and self-fluxing (R = 1.10) PVTM sinters. When the production capacity of the acid pellet was in shortage, the acid PVTM sinter (R = 0.50) could be produced by the surplus from the sinter plant. This replaced a part of the acid pellet and the burden structural model of the blast furnace smelting vanadium so the titanium burden could adopt a ‘high-basicity PVTM sinter + acid V-Ti pellet + acid (R = 0.50) PVTM sinter’.

Prediction NOx emission from sintering plant with a radial basis function and back propagation hybrid neural network

Prediction NOx emission from sintering plant with a radial basis function and back propagation hybrid neural network

Sources of Magnetic Particles from Air Pollution in Mountainous Area

Measurement of magnetic susceptibility of topsoil represents a very useful tool for the detection of atmospherically depositedmagnetic particles. The samples of forest soils from the Moravian-Silesian Beskydy Mountains (the Czech Republic) were used foridentification of emissions sources of particles with magnetic ordering. Magnetic susceptibility was measured at bulk samples ofgrain size class under 2 mm. Microanalysis using electron microscope with an energy dispersive X-ray spectrometer was used forthe determination of particles in the magnetic fraction. The samples of dust from the sintering plant of the Iron Works in the townof Třinec were analysed. The values of magnetic susceptibility of forest soils in the Třinec region are increased. In the relatively nearvicinity of the industrial area, the average value for Javorový Mount was 7.90×10-6 m3/kg, for Ostrý Mount it was 6.69×10-6 m3/kg. It was proved that they were higher than the average values from the Beskydy Mountains (4.64×10-6 m3/kg). The concentrationsof lead and magnetic susceptibility in soils showed significant correlation dependence (rs = 0.85). The iron and steel industryrepresent the primary source of the pollution load in forest soils of the studied area. Statistically, significant dependences betweenthe organic matter content and the lead and zinc concentrations as well as between the magnetic susceptibility values and the ironconcentrations in forest soils were found. It was confirmed that the airborne particles are deposited on vegetation and accumulatedin the organic horizon of forest soils.

Occurrence and spatial distribution of dioxin and dioxin-like compounds in topsoil of Taranto (Apulia, Italy) by GC-MS analysis and DR-CALUX® bioassay

The aim of the present study was to assess the occurrence and spatial distribution of PCDD/Fs and dioxin-like compounds in topsoils of Taranto (Apulia Region), one of the most heavily industrialized and contaminated area of Southern Italy. A combined approach of chemical analysis by GC-MS/MS and AhR reporter gene bioassay was applied in a subset of topsoil samples (n = 20) collected in 2017-18 from ten sites embracing three levels of risk (from high to low) in the framework of a large survey inside Taranto municipality. TCDD-BEQs and GC-MS/MS TEQWHO and TEQTHEORETICAL revealed a decreasing trend with the distance from main industrial settings and landfill areas. A strong correlation between TCDD-BEQs and TEQWHO values (R2 = 0.85) and TEQTHEORETICAL (R2 = 0.88) was also found. In 3 out of 10 topsoil investigated, BEQs and TEQWHO/THEORETICAL resulted above Italian National Regulatory Limits for ∑PCDD/Fs in green, private and recreational used soils (10 ng TEQ/kg d.w. D.Lgs 152/2006) and for ∑PCDD/F/dl-PCBs in agricultural and farming soil (6 ng TEQ/kg d.w. D.M. 46/2019). GC-MS/MS pattern revealed the highest prevalence of dl-PCBs in 6 out of 10 sites, followed by PCDFs and PCDDs. Those sites are all located in proximity of main industrial steel and iron ore sinter plant, steel plant’s landfills and illegal dumping sites. An update on occurrence and spatial distribution of PCDD/Fs and dl-PCBs contamination of Taranto urban soils was obtained and the DR-CALUX® bioassay was further recommended as a suitable screening tool for environmental and human risk assessment.

Technological parameters determining the sintering process intensity

The sintering intensity is an important factor determining techno-economic efficiency of sinter production which provides the blast-furnace process with the main type of agglomerated iron ore raw materials. The charge sintering rate depends on technological parameters of the sintering process. Therefore, a systematic study of sintering technological parameters, which determine its intensity, is of practical and scientific interest. Indicators of the sintering process intensity are considered that assess it from both the mechanical and heat engineering positions. It is shown that in its purest form the sintering process intensity is characterized by the vertical agglomeration rate and combustion intensity of the sintering charge carbon. Two other indexes − the specific productivity for suitable sinter and intensity of heat output in the combustion zone – are less representative for the comparative estimation of sintering intensity, since their values depend on sintered mass strength and thermal effect of carbon combustion respectively. These factors go beyond the essence of the sintering intensity concept. Since content of fines of 5 – 0 mm at different sinter plants is not equal, representative performance comparison of sintering process is possible only taking into account the total amount of fines generated throughout the agglomerate transport path from sinter machine to blast furnace or the results of testing the agglomerate strength in a drum. A comprehensive systematic classification of techniques has been developed to intensify the sintering process based on the material-component principle using four levels of separation – objects, directions, paths and methods in which each subsequent level concretizes and develops the previous one. Its value is universality, which makes it possible to apply a systematization and separation system for almost all already known and future methods of sintering process intensification.

Steam Production From Waste Heat Sources of a Steel Plant

The objective of the following paper is to confirm, based on a pre-engineering study and a first techno-economic evaluation, the potential of waste heat recovery in the industrial area of Dunkirk. This steam will be used for regeneration of the solvent of the full-scale CO2 capture unit (1,5MtCO2/yr). Results of this study will seriously impact the cost of CO2 capture and, by consequence, the economy of the whole chain. It will be one of the main challenges of 3D project as this kind of study has never been carried in a European steel mill. Innovative solutions will be needed. The need of steam is estimated at 155 MW for a full-scale DMX (200 t/h steam at 180°C). Arcelor Mittal processes generate many sources of lost heat, which could be used for DMX solvent regeneration. Heat recovery potentials have been quantitatively evaluated in terms of annual energy quantity, available power and temperature levels. The waste heat capacity is reaching 1GW through 17 sources. The heat sources are the following: - In the coking plant: extinction of the coke, heat from the coke oven gas, fumes from the coke furnace, - In the sinter plant: heat from the sinter cooler, from wind boxes under the sinter bed, from the air of the dust collector, - In the blast furnace: fumes from cowpers, heat losses from blast furnace slags and gas, - In the steel shop: heat losses from convertors, hot slabs from the continuous caster, mist from continuous casters cooling, slags from the steel shop, - In the hot strip mill: fumes from the reheat furnaces of the hot strip mill, walking beams, laminated steel cooling. However, only few of the previous waste heat can be used for the DMX. Indeed, the level of temperature, the separation distance between each heat source and the CO2 capture unit and the technological maturity have been considered to confirm the feasibility to recover heat from each source. Which quantity of steam can we produce at 10 barA for the DMX? Almost 50% of the target, can be reach by developing the following waste heat recoveries: - Heat recovery in the steel shop (heat losses from convertors): 30t/h of steam at 10barA - Heat recovery in the sinter plant to feed the DMX (sinter cooler and air under sinter bed): 45t/h of steam at 10 barA - Heat recovery on slabs just after oxycutting: 15 t/h of steam at 10 barA However, additional solutions will be necessary to reach a production of 200t/h of steam. It may be on coke extinction or heat recovery on slabs in the slab park. Each heat recovery has its technical constraint. The recovery on BOFG cooling (heat losses from convertors) is a well-known technology, but in Dunkirk, it may be very expensive because of structural cost. The recovery on the sinter cooler will be the most accurate in term of distance with the DMX but the temperature is not high enough (air at 220°C). The recovery on continuous casting after oxycutting is the most accurate in term of economical constraints but there is not a lot of space available. The recovery on coke quenching is the most accurate in term of technology available and quantity of steam but very expensive. As alternate it will be also considered the building of a new boiler fed with steel mill gas in excess. It might seem like the easiest solution as a great volume of gas is flared. The available power from steel-production gases is greatly higher than DMX need, which means that it could serve as backup for heat recovery systems. As alternate it has also been considered the available heat sources in the neighboring of the ArcelorMittal site. However, compared to Arcelor Dunkirk heat potential, the heat recovery on other sites is far less interesting as the heat volume is low and the distance might be greater. This solution has not been retained for the next phases. In a nutshell, the steam production optimum sizing from waste heat will be presented in this paper.

Direct Observation of Sulfate Explosive Growth in Wet Plumes Emitted From Typical Coal‐Fired Stationary Sources

AbstractThe origins of atmospheric sulfate production have previously been explained by focusing on air quality models and complex chemical reaction processes. Here, we first report direct observations of sulfate production in stack plumes discharged from coal‐fired power plants, industrial boilers, and sintering plants equipped with wet desulfurization systems. Less than one third of the particulate SO42− in plumes is attributed to dust‐SO42− and SO3 measured in stacks. The SO2 aqueous‐phase oxidation process is critical in explaining the unknown sulfate formation in plume droplets with pH values ranging from 2.3 to 2.8. When the rapidly formed sulfate in wet plumes is included, a notable amount of underestimated sulfate (∼0.24 Tg in 2017) is emitted from industrial stacks in China and can partially explain the “missing sulfate” on driving most particle pollution episodes. Policy‐making targeting particulate emissions is suggested to substantially reduce sulfate emissions for further air quality improvement.

Study of Frequent Failures of the Pressure Roller at Sinter Plant

Pressure rollers are used for gripping pellet cars as they travel through the track. Of 776 pressure rollers, four were found broken after three years of service in a pellet plant of an integrated steel plant. Fatigue cracks had initiated from heavy dent marks at outer surface in all the failed roller. Microstructural analysis revealed dents with some foreign particles embedded on them. EDS analysis of particles showed the presence of iron, calcium and oxide and sulfide elements, indicating presence of FeO with CaS, which are components of sinter particles. No grain deformation was observed around the dents as these were created by sinter particles which are softer than rollers (i.e., a hardness of ~ 450–600 HV against 770 HV for the rollers). After creating these “soft” dents, the sinter particles got embedded in them. Subsequent crevice corrosion caused pits to form, a result of the difference in oxygen potential between the sinter particles and the roller. Sinter fines were probably deposited on the sprocket teeth at either the discharge or the feed ends. The surface roughness (Ra) of used and failed rollers were measured, post which it has been recommended that rollers that develop a surface roughness, Ra higher than 4.5 should be replaced to avoid a failure. This maintenance practice has been implemented in plant with an elimination of such failures.