Sinter Plant Research Articles

Receptor modelling of airborne particulate matter in the vicinity of a major steelworks site

In this study, the Multilinear Engine (ME-2) receptor model was applied to speciated particulate matter concentration data collected with two different measuring instruments upwind and downwind of a steelworks complex in Port Talbot, South Wales, United Kingdom. Hourly and daily PM samples were collected with Streaker and Partisol samplers, respectively, during a one month sampling campaign between April 18 and May 16, 2012. Daily samples (PM10, PM2.5, PM2.5–10) were analysed for trace metals and water-soluble ions using standard procedures. Hourly samples (PM2.5 and PM2.5–10) were assayed for 22 elements by Particle Induced X-ray Emission (PIXE). PM10 data analysis using ME-2 resolved 6 factors from both datasets identifying different steel processing units including emissions from the blast furnaces (BF), the basic oxygen furnace steelmaking plant (BOS), the coke-making plant, and the sinter plant. Steelworks emissions were the main contributors to PM10 accounting for 45% of the mass when including also secondary aerosol. The blast furnaces were the largest emitter of primary PM10 in the study area, explaining about one-fifth of the mass. Other source contributions to PM10 were from marine aerosol (28%), traffic (16%), and background aerosol (11%). ME-2 analysis was also performed on daily PM2.5 and PM2.5–10 data resolving 7 and 6 factors, respectively. The largest contributions to PM2.5–10 were from marine aerosol (30%) and blast furnace emissions (28%). Secondary components explained one-half of PM2.5 mass. The influence of steelworks sources on ambient particulate matter at Port Talbot was distinguishable for several separate processing sections within the steelworks in all PM fractions.

Study on the impact of industrial flue gases on the PCDD/Fs congener profile in ambient air

The aim of this study was to examine the impact of emissions from combustion processes from sinter, medical, waste and sewage waste incineration plants on the PCDD and PCDF congener profile in ambient air in Krakow (city in Poland).The subject matter of the study were air samples from the outskirts and the city center.It was found that in flue gases from industrial sources and in ambient air the share of PCDF congeners in relation to the total content of PCDD/Fs was higher than the share of PCDDs. However, in air samples collected in the city center, this relationship was reversed.The PCDD congener profiles in flue gases and in air samples are comparable. However, in the samples from the city centre, the share of OCDD is significantly higher and amounts to about 80%.The PCDF congener shares show higher spatial diversity, although in all the analyzed air samples, ODCF and 1,2,3,4,6,7,8 HpCDF dominated.Analyzing the share of congeners in regard to the sum of PCDDs/Fs a mutual resemblance of air from the suburbs, exhaust gases from the sinter ore and sewage sludge incinerator plant was observed. The study showed a similarity between the profile of congeners in air from the city centre and exhaust gases from the medical waste incinerator.

Studies into the formation of PBDEs and PBDD/Fs in the iron ore sintering process

Polybrominated diphenyl ethers (PBDEs) and polybrominated dibenzo-p-dioxins and furans (PBDD/Fs) were detected in stack emissions from UK sinter plants. The sum of 36 PBDE congeners was measured at a mean concentration of 295ng/Nm3 with a standard deviation of 96ng/Nm3. The mean PBDD/F concentrations were 0.14ngWHO-TEQ/m3 (range=0.03–0.39). PBDD/F emission concentrations were approximately ten times lower than their PCDD/F homologues. To understand the possible formation mechanisms of brominated organic species in iron ore sintering, both full-scale and laboratory experiments using an experimental sintering process were carried out. A complete PBDE mass balance was undertaken for a full scale sinter plant showing that PBDEs were already present in the raw materials such as iron ores and coke breeze and that a significant proportion of the PBDE inputs were actually destroyed during the process. A number of controlled experiments were conducted using a laboratory-scale sintering apparatus (sinter pot). These were designed to investigate: (a) mass balance of PBDEs during sintering, (b) the relationship between the availability of bromide (as KBr) and PBDE emissions, and (c) the influence of the availability of both bromide and PBDEs on PBDD/F formation. As observed in the full scale plant, the PBDEs already present in the raw materials were mostly destroyed during the process (79–96%) for all sinter pot experiments. Increasing amounts of KBr in the raw sinter mix did not result in a significant increase in PBDE formation suggesting that there was no PBDE formation in sintering via de novo synthesis. No relationship was observed between PBDE inputs and PBDD/F emissions indicating that PBDEs did not act as precursors for PBDD/Fs formation. Finally, PBDD/F formation was enhanced substantially with increasing amounts of KBr suggesting that their formation mechanism was similar to that of PCDD/Fs via de novo synthesis.

POP emissions from a large sinter plant in Taranto (Italy) over a five-year period following enforcement of new legislation

PCDD/F in exhaust gas emission samples was determined by the Environmental Agency of Apulia for a sinter plant located in Taranto (Italy) starting from June 2007 following an Agreement Act between plant owners and the Regional Government with the aim to assess and improve the environmental performances of the plant. The first two sampling campaigns yielded results ranging between 3.42 and 8.34ng I-TE/Nm3 that were soon considered revelatory of a high potential impact on the surrounding environment and the public, prompting for immediate action. As a first outcome, a Regional Regulation (LR 44/2008) was enforced in order to reduce PCDD/F emissions by plants operating in the metal sector, including sinter plants. After installation of a urea addition plant to the sinter mix as a process-integrated abatement technique the emissions ranged from 0.86 to 3.59ng I-TE/Nm3. In order to reach compliance to the newly introduced emission limit value of 0.4ng I-TE/Nm3 the urea plant was removed in favour of active-carbon injection as an end-of-pipe technique. Subsequently, during year 2011 emission values ranged from 0.095 to 1.97ng I-TE/Nm3, while in 2012 the observed range was 0.058 to 0.91ng I-TE/Nm3. As a better evaluation of the potential impact of the sinter plant emissions, a yearly mass-flow was estimated using exhaust gas PCDD/F concentrations and plant operational parameters (3.4MNm3/h). Mass-flow was estimated to be as high as 165g I-TE/year for 2007 using yearly average concentrations or 248g I-TE/year using the peak-value of 8.34ng I-TE/Nm3.

Derivation of Optimal Operating Combination for High Sintering Productivity

In this study, we have proposed an optimal operating combination for the purpose of increasing sintering productivity in various mixed amounts of fine ore. Three operating parameters, including the quicklime ratio, bed height and bulk density, were selected and all experiments were conducted in a pilot-scale sinter pot to simulate various conditions of sintering in a real-scale sinter plant. This study showed that the optimal quicklime amount was 2% when the mixing amount of fine ore was 0% and 7.5%, and 2.5% was the optimal quicklime amount when the mixing amount of fine ore was 15% and 22.5%. Productivity decreased with increased bed height and bulk density regardless of the mixing amount of fine ore. Strength increased with increased bed height and decreased bulk density. It should be noted that the results obtained from the present study were based on pilot scale experiments, and confirmation tests in a real scale plant are still necessary in the future.

Air classification of blast furnace dust collected in a fabric filter for recycling to the sinter process

Totally dry cleaning has become a common technology for top gas cleaning in blast furnaces in recent years. A significant advantage of totally dry gas cleaning is that the dust collected is obtained as dry powder, thus simplifying the recycling of the dust in the sinter plant and avoiding aqueous emissions. The concentration of some heavy metals, especially zinc, in the collected dust is usually higher than the maximum tolerable concentration for recycling to the sinter process. Therefore, a process for separation of dust with a low level of contamination from the rest is necessary to make partial recycling possible. This is possible because the limited components are more volatile and accumulate in the finer dust fraction. In wet blast furnace top gas cleaning, hydrocyclones are well established for this separation. For the separation of dry powder from the dry dedusting process air classification can be used. Dust from the top gas of a blast furnace with a fabric filter for dry top gas cleaning was split into several size fractions using a laboratory air classifier. The concentration of Ca, Cd, Cl, Cu, Fe, K, Na, Pb and Zn was analysed for each particle class and the loss on ignition was determined. A strong dependence of the concentration on the particle size was found for the more volatile metals, whereas the Fe and Ca concentration and the loss on ignition were quite evenly distributed. With the calculated recovery–removal-functions the possible recycling rate can be estimated for a given removal rate for the limited components.

PCDDs/Fs Pollution from Metallurgical Processes in the Town of Sisak, Croatia

Abstract In order to calculate the emission of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans from metallurgical processes located in the town of Sisak, Croatia, this research has built on experiences from developed countries, where the emission factor values from individual metallurgical processes have been taken from the reference data and used for the estimate of the emission of these pollutions in the European countries. The calculation of the emission polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans from metallurgical processes located in the town of Sisak took into account annual outputs of sinter, pig iron, steel blooms and steel billets, as well as steel casts. The metallurgical processes installed in the town of Sisak between 1950 and 2010 emitted from Q1-TEQ =17 mg a-1 PCDDs/Fs in 2001 to Q1-TEQ =5823 mg a-1 in 1989, depending on the activity of these processes. Within the observed period, the largest source of PCDDs/Fs emission was the iron ore sintering plant. Within the observed timeframe, the town of Sisak did not experience any excessive air, soil or water pollution by polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans from the local metallurgical processes.

IRON ORE SINTERING PART 2. QUALITY INDICES AND PRODUCTIVITY

Sinter plants have to process mineral mixes in order to obtain sinter of a suitable composition and quality to be loaded into the blast furnace. For this purpose a series of parameters need to be taken into account, such as the nature and composition of each component of the mineral mix and the conditions of the manufacturing process. Sinter is subjected to in-depth characterisation in terms of chemical and granulometric analysis, determination of the mineral phases in its structure and of quality indices such as reducibility, low temperature degradation, reduction degradation, and tumbler strength. It is also important to operate sinter plants with high productivity and to ensure a uniform sinter composition and quality so as to facilitate the steady state operation of the blast furnace.

An Innovative Magnetic Charging Chute to Improve Productivity of Sinter Machine at Rourkela Steel Plant

Sintering is a process in sinter machine for agglomeration of iron ore and other raw material fines into a compact porous mass, i.e., sinter, used in Blast Furnaces as an iron bearing input charge material for hot metal production. ‘Permeability’ of sinter-bed on sinter machine i.e., the porosity in sinter-bed of charged materials, facilitates atmospheric air passes from the top to bottom across the depth of sinter-bed, when suction created from the bottom of the bed, for efficient heat carry over from top to bottom of the bed for complete burning of charged materials for effective sintering process controls the productivity of the sinter machine. The level of ‘permeability’ in sinter-bed is depending upon the effectiveness of ‘charging chute’ in size-wise ‘segregation’ of charge materials across the depth in sinter-bed, achieved due to differences in the sliding velocities of particles during charging into the moving sinter-bed. The permeability achieved by the earlier conventional ‘charging chute’ was limited due to its design and positional constraints in sinter machine. Improving the productivity of sinter machine, through increased permeability of sinter bed is successfully achieved through implementation of an innovatively designed and developed, “Magnetic Charging Chute” at Sinter Plant no. 2 of Rourkela Steel Plant. The induced magnetic force on the charged materials while the charge materials dropping down through the charge chute has improved the permeability of sinter bed through an unique method of segregating the para-magnetic materials and the finer materials of the charge materials to top layer of sinter bed along with improved size-wise segregation of charge materials. This has increased the productivity of the sinter machine by 3% and also reduced the solid fuel consumption i.e., coke breeze in input charge materials by 1kg/t of sinter.

Kinetic reduction of mill scale via hydrogen

Mill scale is very attractive industrial waste since it is rich in iron (about = 72 % Fe) and it is suiTab. for direct recycling to the blast furnace via sintering plant. In this paper the characterizations of raw materials were studied by different methods of analyses. The produced briquettes were reduced with different amounts of hydrogen at varying temperatures, and the reduction kinetics was determined. Two models were applied and the energy of activation was calculated.

NOx removal coupled with energy recovery in sintering plant

In this paper, a new NOx removal control technique coupled with energy recovery in a sintering plant is proposed. On the basis of energy calculation, it was found that the energy of sintered ore was large enough to supply the energy necessary to heat effluent flue gas to the catalytic temperature window. Moreover, the experimental results showed that sintered ore had a significant effect on catalytic reducing NO with adding NH3. The maximum NO catalytic reduction efficiency could reach 38% at 673 K, which means that the effluent flue gas from a sinter machine did not need further treatment to reach the limit of national pollutants emission standard of China.

Optimisation of MgO addition in low and high silica iron ore sinter to improve sinter reducibility at JSW Steel Limited

The quality of iron ore sinter mainly depends on sinter mineralogy, which in turn depends on the chemical composition of the sinter mix. The reduction properties of the mineral phases formed in the sinter influences the sinter reducibility. MgO has a varying effect on sinter reducibility at different silica contents. A recent trend in blast furnace operation shows that there is a considerable increase in usage of dolomite as a basic flux either directly or through sinter. Recently the silica levels in the sinter product of Sinter plant 1(SP1) of JSW Steel Limited have been fluctuating in the range of 5·5–9·6% due to variation in silica content of iron ore fines. At the same time, as per blast furnace requirement, the addition of dolomite has been changed from 2·4 to greater than 3·0% at SP1, and the reducibility of the sinter decreased (<60·0%). Laboratory pot grate sintering experiments have been carried out to determine the influence of MgO addition on microstructure and reducibility of low and high silica sinter. MgO additions have been varied from 1·4 to 3·2% for low silica (4·5%), and high silica (6·3%) iron ore fines.From the studies it was found that the reducibility of both sinters decreased with increase in MgO addition due to an increase in magnetite/magnesio spinel phase and silicate/slag phase. Reducibility of low silica sinter was greater with high silica sinter. High silica with high MgO sinter had lower reducibility compared to low silica with low MgO/high MgO and high silica with low MgO sinter.

Influence of MgO addition on microstructure and properties of low and high silica iron ore sinter

The quality of iron ore sinter mainly depends on sinter mineralogy, which in turn depends on the chemical composition of the sinter mix. Dolomite is the critical additive for fluxing the sinter and controlling the sinter MgO. Recently, the silica level in the sinter product of the sinter plant 1 has been varying in the range of 5·51 to 9·58% owing to variation in silica content of iron ore fines. At the same time, as per the blast furnace requirement, the rate of addition of dolomite has been changed from 2·40 to greater than 3·00% at the sinter plant 1. In iron ore sinter, MgO plays different roles on sinter properties at different silica ranges. Because of wide range of fluctuation in iron ore silica it is essential to optimise the MgO addition in sinter mix to get desired properties. Laboratory pot grate sintering experiments have been carried out to know the influence of MgO addition on microstructure and properties of low silica and high silica sinter. MgO addition has been varied from 1·40 to 3·20% for low silica (4·47%), and high silica (6·25%) iron ore fines. High silica with high MgO sinter showed lower strength, higher reduction degradation index, and lower reducibility compared to low silica with low and high MgO and high silica with low MgO sinter. To achieve better sinter properties MgO content in the sinter should not be more than 2·80% when silica is more than 6·0%.

New model of the sintering process

Dimensional analysis is used to construct a new mathematical model that establishes a closer relationship between the unit productivity of a sintering machine and the parameters of the sintering operation. An analysis is performed to determine how the unit productivity of the sintering machine is affected by the total gasdynamic resistance of the bed, the coarseness of the material being sintered, the unit load complex, and the duration of the sintering operation. gasdynamic resistance of the bed, duration of the sintering operation, height of the bed, bulk density of the charge, coarseness of the material. Modern sinter plants are a complex system of different types of equipment that operate in different regimes and have different technological functions. The growth of sinter production is being accompanied by intensification of the auxiliary and production operations that are performed. The overall increase in sinter output and a tightening of requirements on sin- ter quality and the ability of the various operations to be performed under flow-line production conditions are creating a good opportunity for the broad introduction of automated monitoring and control equipment. Such equipment should be developed by economics- and mathematics-based methods and should maximize the productivity of the sintering machine and make the most efficient possible use of the raw materials, fuel, and capital expenditures while ensuring a certain level of product qual- ity and protecting the environment. Automated systems developed to control sinter production should also improve the orga- nization of production operations and provide for real-time control over the production process. One tool that can be used to automate sinter production is mathematical modeling. The mathematical models which are constructed can be employed to create suitable control algorithms that can work with existing hardware and software. The unit productivity of a sintering machine is one quantitative criterion of the efficiency of the sintering process. The following are the main factors that affect the efficiency of this process: the coarseness and material composition of the material being sintered; the coarseness and quantity of fuel supplied to the charge; the charge's moisture content; the coarse- ness and quantity of undersized sinter; the coarseness and quantities of the various additives that are used; the height of the bed of charge materials on the sintering machine; the vacuum created by the exhauster; the efficiency with which the charge is mixed; the character of the charging operation and the associated segregation of different charge components; the presence of different "sublayers" in the bed of charge materials; the initial temperature of the charge. The studies (1, 2) presented a mathematical model that determines the dependence of the unit productivity of a sin- tering machine W (kg/(m 2 ·sec)) on the total gasdynamic resistance of the charge bed p (kg/(sec 2 ·m), sintering time τ (sec), bed height h (m), the bulk density of the charge ρ (kg/m 3 ), and the coarseness of the material being sintered. The last param- eter is expressed through the equivalent diameter of the balled charge d (m). The model has the form

An Intelligent Permeability Optimization System at Sinter Plant of Rourkela Steel Plant

The permeability of sinter mix is one of the vital parameters that affect the performance of sintering process. The amount of water added in the granulation drum has a significant effect on the permeability of the sinter bed and sinter machine productivity. Considering the variation in input feed materials and the parabolic nature of permeability-moisture curve, the optimum level of water addition is a difficult task for the operator to determine. Therefore a mathematical model based intelligent permeability measurement system is developed which determine the required amount of water to be added in granulation drum to achieve the optimum permeability based on the given input material.

Life cycle assessment of steel production in Poland: a case study

Abstract The goal of this study is to perform a life cycle assessment (LCA) of steel production through the integrated steel production and electric arc furnace routes in Poland. The study defines the major sources of environmental impacts and proposes pollution prevention methods for the most pollutive steelmaking processes. The LCA methodology based on the ISO 14044 standard is used with SimaPro 7.3.3 software and the Ecoinvent database. The life cycle inventory shows data averaged from the existing steel plants in Poland, and the impact assessment results indicate that the production of pig iron in blast furnaces has the highest impact on greenhouse gas emissions and fossil fuel consumption in the national integrated steel production route, while the iron ore sintering process, which is the largest contributor to dust and gas emissions in the national iron and steel industry, uses the most minerals and depletes the most metal. Electricity consumption has the highest impact on greenhouse gas emissions and fossil fuel consumption in the national electric arc furnace route. Therefore, this article presents the results of an LCA of alternative fuel consumption in a national iron ore sinter plant. The study concludes that pollution prevention methods related to raw material substitutions in iron-making processes should be used to reduce environmental impacts in the iron and steel industry. The results of this study can be used as the first step in performing a full cradle-to-grave steel LCA that includes all phases of the steel life cycle.

Study on Cyclone Dust Removal Equipment after Dense Phase Semi-Dry Flue Gas Desulfurization System

In order to achieve the purpose of pre-dusting device efficiency, low resistance, energy-saving after dense phase Semi-dry flue gas desulfurization system. In this paper, computer numerical simulation as the main research method, use single factor and orthogonal method, simulation study of the various factors that affect the performance of the octagon separator, get the law of different factors for separator performance. And designing a separator structure model, use this model as a sintering plant dense phase pre-dusting device after the semi-dry flue gas desulfurization system, get the separation efficiency of 37.6% , obtain the desired effect of better engineering.

Modeling dependence of the strength of agglomerates on their basicity

An attempt was performed to clarify and summarize mathematically an extreme dependence strength-basicity of agglomerate based on polymorphism of Ca2SiO4. Two main indicators underlaid the sinter production: a mechanical strength and specific performance of a sinter plant, which can be expressed by yield of a certain size fractions after physical stress and by linear sintering rate, respectively.

Failure analysis of hot sinter screens of a sinter plant

Failure analysis of a sinter screen in a sinter plant has been presented. The sinter screen is used for removing fines (<5mm size) form the crushed hot sinter (temperature around 1000°C) thereby facilitating the cooling of sinter as well as smooth running of blast furnaces. The screens are cracking prematurely within 15days. The material of the failed screens is found to be ASTM A297 HK 40 which is basically a heat resistant cast austenitic stainless steel alloy. Based on the failure analysis, a new material HK 40 (Nb modified) has been recommended which increases the service life of the component by 6times. Samples of both HK 40 and HP 40 steels from unused and used screens are collected for analysis. The analysis consists of plant visit and visual observation, chemical analysis, fractography, microstructural examination using optical and scanning electron microscopes, characterization with EDS analysis, and measurement of hardness, impact toughness and wear properties. The analysis reveals that HK 40 screens are cracking because of material degradation at elevated service temperature due to formation of sigma phase along with chromium carbide network leading to intergranular corrosion. Further, HK 40 screen exhibit significant increase in hardness and decrease in impact toughness after service compared to that of HP 40 due to material degradation. Microstructural examination of HP 40 steel does not exhibit any sigma phase formation and intergranular corrosion. A comparative study of HK 40 and HP 40 steels before and after service as hot sinter screen has been carried out.

Improvement in the Life of Cold Sinter Screen Decks of Sintering Plant by Using High Wear Resistant Hard-facing Alloys

Steel Authority of India Limited (SAIL), Research & Development Centre for Iron & Steel (RDCIS), Ranchi, 834 002, India Abstract For smooth operation of the b last furnace, proper size and quality of the input raw materials are very much essential. Sinters produced in the sintering plants are first screened out to remove the undersize fractions before their supply to blast furnaces. The screens are fitted with punched steel deck plates where the undersized sinters are being screened. It was found that the life of these screen decks were very less due to its lower wear and abrasion resistance properties. So to imp rove the life and screening efficiency, high wear resistant hard-facing alloys was used over the base plate for use in the cold sinter screens. A layer of metallic carb ides was deposited over the base plate to achieve higher hardness on the top surface. Simu ltaneously, the slots/ holes in the base plates were modified with increased taper across the thickness of the steel plates to overcome the problem of chocking/ b locking o f holes during screening of sinter fines. The result showed about 4 times life improvement of the sinter screen decks i.e. 12 months from 3 months average. Moreover, <5 mm size fraction of sinter in the blast furnace charge also reduced to 5% fro m mo re than 10% observed earlier.