Sinter Feed Research Articles

Batch Sintering of FeO·OH and Fe2O3 Blends: Chemical and Metallurgical Characterization

A sample of goethite iron ore sinter feed (G_SF) was employed as a raw material in a sintering bed. This sample partially replaced hematite sinter feed (H_SF), which is currently used as raw material in a sintering plant in the state of Minas Gerais, Brazil. This substitution did not adversely affect the chemical and metallurgical proprieties of the sinter mix product, provided that the utilization of G_SF was kept below 30% in weight. Despite the higher proportion of fines in G_SF, the presence of argillaceous minerals in the sample led to an improvement in the granulation index (GI) of the sinter mix product. The GI value increased from 68.4 to 82.7% for the experiments conducted without the presence of goethite ore and with 40% of goethite ore in the sintering mix, respectively. Consequently, the qualities of both the process and the produced sinter product were not compromised. The raw materials and the various sinters produced were characterized through X-ray fluorescence (XRF) and X-ray diffraction (XRD), as well as thermal gravimetric analysis (TGA). The XRD results were used to perform a quantitative assessment of the mineral phase using the Rietveld method (RM). This technique allowed for the determination of goethite content in the studied sample, which was 35.5%. Finally, the incorporation of G_SF in the sintering bed led to a 20% reduction in the cost of raw materials.

Identification of priority pollutants at an integrated iron and steel facility based on environmental and health impacts in the Yangtze River Delta region, China

Emissions from the iron and steel industry are a major source of air pollution. To investigate the composition characteristics, estimate the secondary transformation potential, and assess the ecological risk and human health risks of air pollutants from iron and steel industry, field measurements of volatile organic compounds (VOCs) and trace metals (TMs) were conducted simultaneously from 2020 to 2022 in the Yangtze River Delta (YRD) region, China. The average mixing concentration of VOCs (Σ64VOCs) was 58.2 ppbv. Alkanes, alkenes and aromatics were the major components. Benzene and ethylene were the most abundant VOC species. In the O3 season, the calculated OH loss rates (LOH) and ozone formation potential (OFP) were 10.87 S−1 and 181.74 ppbv, respectively, which increased 39.54% and 21.51% compared to the non-O3 season. Furthermore, the O3-VOCs-NOx sensitivity indicated that O3 formation was under the VOCs-limited regime. The average concentration of total 10 trace metals (Σ10TMs) was 226.8 ng m−3, Zn, Pb and Mn were the top abundant TM species. The results also found that Se was extremely contaminated; Pb and Zn was heavily to extremely contaminated; Cu, As and Ni were moderately to heavily contaminated. For lifetime cancer risk, the cumulative carcinogenic risks were 1.84E-5 for children, 6.14E-5 for adults and 1.83E-5 for workers. The carcinogenic risks of individual chemicals cannot be ignored, especially for Cr, Ni, benzene and 1,3-butadiene. The hazard index values for workers and residents were 0.53 and 2.23, respectively, suggesting a high non-carcinogenic risks to the exposed population. These findings deepen the understanding of the pollutant character of the iron and steel industry, and provide theoretical support for policy development on O3 pollution treatment and human health in the YRD region, China. For the study area, we recommend utilizing high-quality raw coal, reducing the volatile hydrocarbon content in the sinter feed, and installing absorption device for highly reactive VOC components at the exhaust outlet.

Optimized Prediction Model for the Granulation Effectiveness of Sintering Mixtures

The optimization model is proposed on the basis of the Litster's granulation model for the prediction of the granulation effectiveness of the sinter feed. Formulas are proposed to calculate parameters for the adhesive layer of the granules, including its mass‐averaged particle size and the water saturation. Based on small‐scale granulation and sieving experiments, a functional correlation is established that relates the granules properties to the distribution coefficient curve, confirming the validity of the model. The prediction of model is discussed with adhesive layer boundary conditions of −0.25, −0.5, and −1.0 mm, and when the boundary is −0.5 mm, the relative error is minimal. The optimization of the distribution coefficient curve based on the binomial interpolation method can make the model achieve a hit rate of 92.9%. Based on this model, the granulation effectiveness of the mixtures could be evaluated.

Monitoring of Iron Ore Quality through Ultra-Spectral Data and Machine Learning Methods

Currently, most mining companies conduct chemical analyses by X-ray fluorescence performed in the laboratory to evaluate the quality of Fe ore, where the focus is mainly on the Fe content and the presence of impurities. However, this type of analysis requires the investment of time and money, and the results are often available only after the ore has already been sent by the processing plant. Reflectance spectroscopy is an alternative method that can significantly contribute to this type of application as it consists of a nondestructive analysis technique that does not require sample preparation, in addition to making the analyses available in more active ways. Among the challenges of working with reflectance spectroscopy is the large volume of data produced. However, one way to optimize this type of approach is to use machine learning techniques. Thus, the main objective of this study was the calibration and evaluation of models to analyze the quality of Fe from Sinter Feed collected from deposits in the Carajás Mineral Province, Brazil. To achieve this goal, machine learning models were tested using spectral libraries and X-ray fluorescence data from Sinter Feed samples. The most efficient models for estimating Fe were the Adaboost and support vector machine and our results highlight the possibility of application in the samples without the need for preparation and optimization of the analysis time, providing results in a timely manner to contribute to decision-making in the production chain.

Characterization of Magnetic Tailings from Phosphate-Ore Processing in Alto Paranaíba

The characterization studies of tailings from mining are crucial for the development of its reuse processes and the reduction of impacts caused by its conditioning on the earth’s surface. This study characterizes the magnetic tailings from phosphate-rock processing using X-ray diffraction, X-ray fluorescence spectrometry and quantitative electron microscopy techniques. Samples were obtained from the magnetic tailings deposit of a mining company in the Alto Paranaíba region, Minas Gerais. The tailings are mainly composed of hematite/magnetite (74.92%), ilmenite (8.91%), fluorapatite (8.8%), anatase (3.07%), calcite (1.67%), goethite (1.62%), and quartz (1.02%). The particle size of the tailings is smaller than that specified for the production of sinter feed. The hematite/magnetite phase is strongly associated with ilmenite and fluorapatite. New stages of comminution and separation are needed due to the low degree of liberation of these minerals for a possible reuse of the components.

Development and application of a novel fluxing compound for improving sintering performance of high alumina iron ore

ABSTRACT Blast furnaces (BF) ferrous burden consist of sinter (>50%) with rest being pellets and lump ore. Good sinter quality is necessary for efficient BF operation which depends on iron ore quality and its gangue. In gangue, alumina has a strong influence that adversely affects product quality and productivity. To address those effects this study presents a two-stage method. It involves the development of a novel low temperature melting synthetic flux i.e. Iron Rich Calcium Ferrite (IRCF) at Stage-1 and its addition in high alumina sinter feed at stage-II. Microstructural and dilatometry studies show that IRCF encourages the formation of silico-ferrite of calcium and aluminum (SFCA-1). The IRCF addition (6% max) in the high alumina (3.1%) sinter feed improves the Tumble index by 4.7 points, lowers the Abrasion index by 2.7 points, and decreases the return fines by 4.4%. Moreover, the Reduction degradation index (RDI) was also improved by 7.9 points.

Effect of Mixing Pre-heated Water on Granulation and Iron Ore Sinter Properties

Granulation of sinter feed mix is one of the most important factors in determining the permeability of sinter bed and sinter properties like sinter yield, tumbler index, etc. To improve the granulation of sinter feed mix, various technologies like two-stage granulation process, coating granulation process, wet vertical ball mill and use of magnetic water have been reported. In this paper, effect of pre-heated water (30, 60 and 90 °C) on granulation fitness of sinter feed mix was studied using a laboratory mixing drum. Sinter properties were investigated using pot sinter experiments. It was observed that with addition of pre-heated water, granulation fitness i.e., Balling index (BI) and Granulation index (GI) has increased, indicating that wetting of sinter feed mix has improved significantly. Treatment of sinter feed mix with pre-heated water reduces the surface tension of water and improves slaking of lime. This enables improved binding of the small size faction (− 0.25 mm), leading to stronger green ball which results in reduced fine generation during charging to the sinter bed. This further leads to the improvement in bed permeability and sinter properties. Enhanced hydration of lime and improved dispersion of water thus achieved have benefitted granulation fitness (GI increases by 5.3% and BI increases by 9.7%). Sinter yield increases by 2.1% and tumbler index by 1.6%. The results suggest that the proposed methodology is effective in improving the granulation fitness of sinter feed mix and sinter properties.

Evaluation of Iron Ore Concentrate and Micropellets as Potential Feed for Sinter Production

ABSTRACT The use of iron ore concentrate and micropellets as sinter feed was evaluated. Five mixtures containing different proportions of concentrate and micropellets, together with iron ore fines, were granulated and sintered in a pilot scale sinter plant. It was found that the addition of iron ore concentrate and/or micropellets to the sinter feed resulted in a significant increase in permeability of the granulated bed, but a large drop in sinter production rates. Although the introduction of iron ore concentrate and/or micropellets to the sinter mixture did not significantly impact sinter strength or reducibility (as measured through tumble – (TI) and reducibility indices (RI)), it severely impacted on their strengths during reduction (as measured through RDI−3.5 mm and RDI−0.5 mm). The introduction of iron ore concentrate and micropellets resulted in a general increase in the amount of fines that form during reduction, exceeding the maximum acceptable levels (RDI−0.5mm maximum 5%) set by industry. Sinters containing high amounts of micropellets experienced a more severe degradation than the concentrate-rich sinters. It is therefore more viable to use iron ore concentrate in the sinter feed as higher production costs are associated with the production of micropellets. Sinters produced through concentrate addition also generate less fines on reduction.

INFLUENCE OF HEMATITE PARTICLE MORPHOLOGY ON FRIABLE ITABIRITE CONCENTRATION IN HUMPHREYS SPIRAL CONCENTRATOR / INFLUÊNCIA DA MORFOLOGIA DA HEMATITA PRESENTE EM ITABIRITO FRIÁVEL NA CONCENTRAÇÃO POR ESPIRAL CONCENTRADORA HUMPHREYS

The depletion of hematitic mineral deposits and the growing content of itabirites in the iron ores mined in the Quadrilátero Ferrífero - Brazil calls for further studies in an effort to adjust the actual technologies, due to the different behaviors of the different mineral species present in the new ore. Currently, little is known about the fundamentals of particle separation in Humphreys spiral, as far as the different particles morphologies. Therefore, the performance of a spiral concentrator was evaluated by a sequence of friable itabirite tests at an industrial scale. The smallest iron content and smaller metallurgical recovery attained in the tests owe to a small particle size in sample (33.67% < 106 µm and d 80 ? 675 µm) and a greater content of tabular hematite. The sample showing the worst metallurgical recovery results (46.20%) and iron content (62.39%) also presented the highest percentage of tabular hematite (68.69%). The samples with a greater amount of martite produced sinter feed with the highest metallurgical recovery (65.65%). It is believed that there was a predominant effect of the hematite morphology on other parameters such as density. Thus, a careful characterization step and the adoption of blending procedures concerning iron content and morphology simultaneously can be positive for the process.

Analysis of the Effect of Ventilation Bars on the Packing Structure of Sinter Bed by DEM Simulation

The effect of ventilation bars on the porosity of a sinter bed charged on a sinter machine was investigated. The behavior of the sinter feed was calculated by discrete element method (DEM) simulation. By taking into account the adhesion force, the sinter feed in the wet state was represented and the simulation parameters were determined to reproduce the experimental values of the angle of repose. The porosity of the sinter bed was calculated, and the mechanism of the formation of the packing structure and the cause of the distribution of porosity in each region were clarified. As a result, it is shown that in the case of shear flow, the higher the powder pressure during flow, the higher the porosity.

Characterization and drying kinetics of iron ore pellet feed and sinter feed

The moisture content of iron ore must be suitable for safe handling and transporting operations. Here, the characterization and drying kinetics of iron ore concentrates were presented and recommendations for the design of dryers were discussed. Pellet feed and sinter feed showed a high amount of fine particles (8–20% dp <10 µm) and a low pore volume (Vpore <10 µm). An ample period for drying at constant rate was observed (critical moisture around 5%), indicating that drying processes aiming at a moderate moisture reduction could be performed within this period. These findings contribute to the design of dryers and support economic operations.

Flame front progress in gas assisted iron ore sintering

The present paper is focused on the control of heat release and on the propagation of the flame front in an iron ore sinter bed. Small scale sinter experiments are performed in cylindrical packings of the sinter mix which are ignited at the bed surface and vertically passed by the suction gas. The heat front propagation is found to be closely linked to the consumption of the fuel mix in the sinter bed. Based on this findings, a dual fuel approach is explored whereas front propagation of the solid fuel combustion (coke breeze) is supported by pulsed injection of a secondary gaseous fuel. A non-stationary, one dimensional model is established to analyse the heat wave travelling in the sinter bed. The model setup describes a local thermal non-equilibrium between the sinter bed being defined as porous medium and the permeating gas. The model is based on the balance equations for the mass and heat transports caused by the solid and gaseous fuel combustion. Model calculations support the experimental findings and demonstrate that satisfying sinter peak temperature levels and locally focused energy release are ensured by combined solid fuel burnout and high temperature gas combustion. During some lab-scale sintering tests, coke breeze content was reduced in the sinter feed mixture, and secondary fuel gas was supplied in pulsed mode to compensate the missing energy demand. The flame front speed as well as properties related to the sinter quality such as the tumble and shatter strength were determined, with the later index showing more sensitive results. The investigations demonstrate that pulsed methane injection can increase the flame front speed compared to the pure coke case with 5.1 wt% coke. , the pulsed gaseous fuel combustion can nearly compensate the strength loss for a moderately coke reduced rawmix with a coke content of 3.5 wt%.

Segregation Charging Behavior of Ultra-Fine Iron Ore Briquette in Sinter Feed Bed: DEM Analysis

The sinter–briquette complex firing process which is an effective technology for utilization of low grade ultra-fine ore is a method for charging sinter feed mixed with briquette made of ultra-fine ore. To uniformly fire briquettes using the excess heat from the lower part of the sinter feed bed, they must be segregated in that region. In this study, the particle properties and interaction coefficients of real samples were measured and used for a numerical analysis. Furthermore, a discrete element method simulation was used to investigate the characteristics of the sinter feed and briquette charging process, namely burden distribution and porosity, by varying the shape and mixing ratio of the briquette. The results showed the while the shape of the briquette did not affect the burden distribution and porosity, the porosity at the lower part of the bed proportionally increased with the briquette mixing ratio. Furthermore, it was observed that to achieve optimized heat distribution of the bed, the proportion of briquette in the charging mixture should be more than 20%.

Granulation Effectiveness of Iron Ore Sinter Feeds: Effect of Ore Properties

Granulation Effectiveness of Iron Ore Sinter Feeds: Effect of Ore Properties

Charging Behavior of Sinter Feed according to Types of Charging Chute

Charging Behavior of Sinter Feed according to Types of Charging Chute

Blast Furnace Hearth Lining: Post Mortem Analysis

The main refractory lining of blast furnace hearth is composed by carbon blocks that operates in continuous contact with hot gases, liquid slag and hot metal, in temperatures above 1550 oC for 24 hours a day. To fully understand the wear mechanism that acts in this refractory layer system it was performed a Post Mortem study during the last partial repair of this furnace. The samples were collected from different parts of the hearth lining and characterized using the following techniques: Bulk Density and Apparent Porosity, X-Ray Fluorescence, X-ray Diffraction, Scanning Electron Microscopy with Energy-dispersive X-Ray Spectroscopy. The results showed that the carbon blocks located at the opposite side of the blast furnace tap hole kept its main physicochemical characteristics preserved even after the production of 20x106 ton of hot metal. However, the carbon blocks around the Tap Hole showed infiltration by hot metal and slag and it presents a severe deposition of zinc and sulfur over its carbon flakes. The presence of these elements is undesired because it reduces the physic-chemical stability of this refractory system. This deposition found in the carbon refractory is associated with impurities present in the both coke and the sinter feed used in this blast furnace in the last few years.

Bench-scale calcination and sintering of a goethite iron ore sample

This work presents the results of bench calcination and sintering studies conducted on an iron ore sample from Iron Quadrangle, Brazil with high goethite content. The natural samples and the products of calcination and sintering were characterised by inductively coupled plasma optical emission spectroscopy (OES/ICP), X-ray spectrometry and gravimetric methods. Optical microscopy, X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS) were used to identify the phases in the studied samples. Density, specific surface area, specific pore volume and pore diameter were determined through gas pycnometry. All of the natural sinter feed samples had a Fe grade >64% and a very high phosphorus grade (~0.17%). After calcination, a 3.1–3.4% increase was observed in the Fe grade compared to that of the natural sinter feed samples. The average Fe grade of the sintered samples was 59.1%. The identified phases with XRD in the raw materials were hematite and goethite. In the calcined samples, only hematite was identified because of the thermal decomposition of goethite. The density, specific surface area, specific pore volume and pore diameter of the calcined samples increased compared to those of the natural sinter feed samples. Hematite, brownmillerite, anorthite, and gehlenite were identified in the sintered samples. The sites for phosphorus occurrence were calcium silicates and apatite. The sintered samples exhibited specific surface areas lower than those of the calcined samples. This result was ascribed to the destruction of the pore structure by the sintering process. No relationship between the proportions of nucleate, intermediate and agglomerate particles used in mixture of sinter tests with the results of microtumbler was identified.

Prediction of the granule size distribution of iron ore sinter feeds that contain concentrate and micropellets

Depletion of high grade lump ore and increased blast furnace productivity with the use of prepared burden has resulted in increased use of iron ore sinter and pellets. There is considerable interest in including fine iron ore concentrate and micropellets into sinter mixes. These materials need to be accommodated in the sinter mix without adversely affecting the permeability of the sinter bed. Addition of fine concentrate and micropellets to a sinter mix will significantly affect the particle size distribution of the granules in the sinter feed. This paper describes the prediction of granule size distribution using the model developed by Litster. The effect of concentrate and micropellet addition on the model accuracy was evaluated by comparing the experimental and predicted Sauter mean diameters of the granules and evaluating the mean absolute percentage error (MAPE). It was confirmed that Litster's model can be applied to the tested sinter mixtures to predict the mean granule size, with a MAPE of less than 10%. The results of the model also provide a scope for comparing mean granule sizes, particle growth and the ratio of finer to nuclei particles as the amounts of concentrate and micropellets increase. The granule size decreased with addition of concentrate while the particle growth and ratio of finer to nuclei particles increased. For sinter mixtures that contain micropellets, the granule size, particle growth and ratio of finer to nuclei particles decreased with an increase in the mass fraction of micropellets.

Concentration of manganese tailings via reverse flotation in an acid médium

Beneficiation of manganese ores has been conducted around the world by circuits composed basically of crushing, screening and spiral classifier. Therefore, solely the coarse size fractions (and commonly the richest) are actually recovered: "lump" (-75+9mm) and "sinter feed" (-9+0.15mm). In the industrial plant which processes the ore from the Azul Mine-PA, the overflow of the spiral classifier (- 0.15mm) is disposed of in a tailings dam because it bears a low Mn content (<10%) and high kaolinite content (70%). This paper reports the findings of a process development conducted on laboratory scale with the aim of concentrating Mn-bearing minerals from the tailings of the Azul Mine-PA (7% of Mn and 70% of kaolinite). The process is composed of desliming (-10µm), followed by reverse cationic flotation of kaolinite (rougher, scavenger) at pH~5. Results indicate that the reverse cationic flotation in the acid medium, when utilizing amide amine as collector and in the presence of a silicate activator and a dispersing agent could be a possible route for the concentration of tailings that had previously been deslimed at 10µm. The results yielded a mass recovery of 18%, a metallurgical recovery of 50% and a 32% Mn concentrate which may be mixed with current high grade products, increasing the overall recovery of the plant.

Air classification of blast furnace dust catcher dust for zinc load reduction at the sinter plant

The off-gas discharged from a blast furnace is de-dusted in a first stage by a dust catcher or a cyclone. The separated dust consists mainly of iron and coke. Therefore, most of this dust is recycled in the sinter plant. A higher Zn content of the dust is undesirable because the allowed Zn content in the sinter feed material is limited. The reduction of the Zn content of the dust by a simple process would be helpful in the case of higher Zn content in the blast furnace dust. In classification experiments, it has been demonstrated that the Zn content of the blast furnace dust increases with decreasing particle size. Thus, air classification of the dust can be applied to separate the Zn-enriched fines. By separating a small fraction of fines (about 10–20 %) from the blast furnace dust, a reduction of the mass of Zn in the remaining coarse fraction for recycling in the range of 40–60 % is possible and only 5–10 % of the carbon is lost.