Iron Concentrate Particles

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Crystals crystals	2.4	4.2	2011	11.1 Days	CHF 2100
Minerals minerals	2.2	4.1	2011	18 Days	CHF 2400

19 pages, 23954 KiB

Open AccessArticle

Effect of Basicity on the Reduction Swelling Performance of Pellets Prepared from Bayan Obo Iron Ore Concentrate Based on Microscopic Characterization

by Yifan Chai, Yingjie Fan, Xing Gao, Guoping Luo, Yici Wang, Shengli An and Jinzhou Liu

Crystals 2022, 12(10), 1399; https://doi.org/10.3390/cryst12101399 - 2 Oct 2022

Cited by 5 | Viewed by 2050

Abstract

The development of blast furnace smelting technology with a high proportion of pellets is an important means for improving the utilization rate of complex co-associated mineral resources. The effect of basicity on the reduction swelling performance of pellets prepared from Bayan Obo iron [...] Read more.

The development of blast furnace smelting technology with a high proportion of pellets is an important means for improving the utilization rate of complex co-associated mineral resources. The effect of basicity on the reduction swelling performance of pellets prepared from Bayan Obo iron ore concentrate is characterized by the aspects of microscopic morphology, element distribution and weight-loss behavior. The results show that with the increase in basicity, the reduction swelling rate and the weight-loss rate of pellets follows the change rule by first increasing and then decreasing. With a basicity of 0.8, the pellets have the largest swelling rate (75.743%) and the largest weight-loss rate (24.77%). The reduction swelling rate is proportional to the porosity and inversely proportional to the amount-of-liquid phase. In the first stage of reduction, pellets with a basicity of 0.8 changed from tabular to granular, and there were a large number of cracks. In the third stage of reduction, pellets with a basicity of 0.8 had coarse iron whiskers. In the same reduction stage, the amount of K and Na elements in the pellets with a basicity of 0.8 entering the iron oxide lattice was much larger than that in the pellets with a different basicity. As the reduction progresses, the ability of alkali metals to enter the iron oxide gradually increases. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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13 pages, 3938 KiB

Open AccessArticle

Experimental Study and Numerical Simulation on Dust Concentration Distribution of Chute at Enclosed Stockyard of Steel Works

by Hongtao Wang, Xuesong Wang, Shengfa Xia and Lei Li

Minerals 2022, 12(9), 1164; https://doi.org/10.3390/min12091164 - 15 Sep 2022

Cited by 1 | Viewed by 1580

Abstract

To clarify the dust concentration distribution of chute at the enclosed stockyard in steel works during the discharging process of materials, the experimental model based on the similarity principle was established in the laboratory, and the effects of the moisture content of materials, [...] Read more.

To clarify the dust concentration distribution of chute at the enclosed stockyard in steel works during the discharging process of materials, the experimental model based on the similarity principle was established in the laboratory, and the effects of the moisture content of materials, the height of chute, as well as the discharging amount of materials on the dust concentration of the selected four materials (MLG-S, ONM-N-F, MLC-N, and ONM-N) were experimentally investigated. Simultaneously, the dust concentration distribution and the motion trajectory of particles were numerically simulated by FLUENT software based on the gas-solid two-phase flow theory. The results showed that a large amount of dust are generated during the discharging process of materials at the enclosed stockyard, and the dust concentration is negatively depended on the moisture content of materials, while that is positively correlated with the height of chute. As the height of chute is increased from 2.2 m to 3.1 m, the concentration of dust generated by the MLG-S is accelerated from 7335.1 mg/m³ to 8881.1 mg/m³, and the concentration of dust produced by the ONM-N is increased from 1286.7 mg/m³ to 1964.3 mg/m³. Meanwhile, the higher dust concentration is from the materials with smaller particle sizes and more fine particles. Furthermore, the dust concentration in the chute space is gradually increased from the top to the bottom, and the bottom of the chute is the key area for controlling dust pollution. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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14 pages, 4928 KiB

Open AccessArticle

Deposit Formation in a Coal-Fired Rotary Kiln for Fluxed Iron Ore Pellet Production: Effect of MgO Content

by Yufeng Guo, Kuo Liu, Shuai Wang, Feng Chen, Zhuang Yang, Lingzhi Yang and Dongyue Li

Crystals 2022, 12(9), 1214; https://doi.org/10.3390/cryst12091214 - 28 Aug 2022

Cited by 2 | Viewed by 2026

Abstract

During the roasting process of fluxed pellets in a coal-fired rotary kiln, the incomplete combustion of pulverized coal injection accelerates deposit formation, which further limits the production efficiency of fluxed pellets. In order to eliminate the above problem, this study investigated the influence [...] Read more.

During the roasting process of fluxed pellets in a coal-fired rotary kiln, the incomplete combustion of pulverized coal injection accelerates deposit formation, which further limits the production efficiency of fluxed pellets. In order to eliminate the above problem, this study investigated the influence of MgO on deposit formation mechanism. The thermodynamic analysis revealed that MgO could increase the melting temperature of silicates in fluxed pellets with 0.8–1.2 basicity (CaO/SiO₂) when roasted at 1200–1250 °C, thereby decreasing the amount of liquid phase that formed initial deposits. XRD and SEM analyses of deposit simulants demonstrated that the addition of MgO was conducive to form magnesium magnetite and ferri-diopside, thereby avoiding the formation of hedenbergite with lower melting temperature. Moreover, the softening-melting performance and adhesivity tests confirmed that MgO had a positive effect on reducing liquid-phase deposition and inhibiting the adhesion of deposits on refractory bricks below 1250 °C. The above studies indicated that the addition of MgO helped to slow down the deposit formation of fluxed pellets prepared by coal-fired rotary kiln. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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14 pages, 5077 KiB

Open AccessArticle

Influence of Specific Surface Area on the Strength of Iron Oxidized Pellets

by Meng-Bo Dai, Bao-Shu Gu, Zhi-Yong Ruan, Zi-Hong Wang, Bang-Cao Luo and Tie-Jun Chun

Minerals 2022, 12(8), 921; https://doi.org/10.3390/min12080921 - 22 Jul 2022

Cited by 5 | Viewed by 2268

Abstract

Blaine specific surface area (SSA) is an essential physical property of iron concentrate and is availably improved by a high-pressure grinding roller (HPGR) to enhance the pelletability and the qualities of oxidized pellets. In this study, the four concentrates with various SSA were [...] Read more.

Blaine specific surface area (SSA) is an essential physical property of iron concentrate and is availably improved by a high-pressure grinding roller (HPGR) to enhance the pelletability and the qualities of oxidized pellets. In this study, the four concentrates with various SSA were obtained by HPGR treatment to produce the oxidized pellets. The results show that the high degree of lattice deformation corresponds to high SSA which is beneficial for improving the quality of green, preheated, and fired pellets. The compressive strength increases from 600 to 1870 N·pellet⁻¹ for preheated pellets and increases from 2530 to 4270 N·pellet⁻¹ for fired pellets when SSA increased from 849 cm²/g to 1601 cm²/g, under the optimal condition of preheating at 1050 °C for 12 min and firing at 1250 °C for 15 min. The oxidation of magnetite is accelerated. Low porosity and microphotographs with integrated hematite joined crystallization support the strength enhancement by high SSA. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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14 pages, 4762 KiB

Open AccessArticle

Effects of Basicity and Al₂O₃ Content on Viscosity and Crystallization Behavior of Super-High-Alumina Slag

by Shuai Wang, Ying Jiang, Yufeng Guo, Zhuang Yang, Feng Chen, Lingzhi Yang and Guang Li

Crystals 2022, 12(6), 851; https://doi.org/10.3390/cryst12060851 - 16 Jun 2022

Cited by 11 | Viewed by 2940

Abstract

The CaO-SiO₂-MgO-Al₂O₃ slags with high alumina content are widely applied in various pyrometallurgical processes. However, for super-high-alumina slags, especially for those with alumina content of more than 25 wt%, there is a lack of relevant studies about the [...] Read more.

The CaO-SiO₂-MgO-Al₂O₃ slags with high alumina content are widely applied in various pyrometallurgical processes. However, for super-high-alumina slags, especially for those with alumina content of more than 25 wt%, there is a lack of relevant studies about the properties of slag. The melting behavior, viscosity, structural property, and crystallization behavior of high-alumina slag with the fixed MgO content of 11.13 wt% and Al₂O₃ content from 27.61 wt% to 40 wt% were investigated. The results revealed that the liquidus temperatures and complete solidification temperatures of slag increased with the increasing binary basicity and Al₂O₃ content. The melting temperature and viscosity of the CaO-SiO₂-11.13wt%MgO-Al₂O₃ slag system increased with the increasing basicity from 0.8 to 1 and Al₂O₃ content from 27.61 wt% to 40 wt%. The increase in Al₂O₃ caused the formation of high-crystallinity and high melting point materials in the slag, such as spinel and Åkermanite. A large number of non-uniform phases could quickly crystallize out of the solids present in the slag melt, thereby increasing the slag viscosity and deteriorating the fluidity of the slag. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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17 pages, 10852 KiB

Open AccessArticle

Green and Efficient Utilization of Ferruginous Gibbsite Ore and Ferruginous Manganese Ore by Synergetic Carbothermic Co-Reduction–Magnetic Separation Process

by Haipeng Chen, Lihua Gao, Wenlong Zhan and Zhijun He

Minerals 2022, 12(6), 671; https://doi.org/10.3390/min12060671 - 26 May 2022

Viewed by 1893

Abstract

The synergetic utilization of ferruginous gibbsite ores (Al-Fe ores) and ferruginous manganese ores (Mn-Fe ores) by the carbothermic co-reduction roasting–magnetic separation process was proposed as an innovative and green process for the separation and recovery of the valuable metal elements of Mn, Fe [...] Read more.

The synergetic utilization of ferruginous gibbsite ores (Al-Fe ores) and ferruginous manganese ores (Mn-Fe ores) by the carbothermic co-reduction roasting–magnetic separation process was proposed as an innovative and green process for the separation and recovery of the valuable metal elements of Mn, Fe and Al from these ores. In this paper, a ferromanganese crude alloy with 72.47% Fe and 10.19% Mn and a high recovery of 85.89% Fe was prepared, which produces an acceptable feed to produce manganese steels with an electric arc furnace. The synergistic co-reduction of the two kinds of complex and refractory minerals was favored to separate Fe, Mn and Al from these ores. The influence of the operating variables on the recovery and separation of valuable metals from Mn-Fe ores and Al-Fe ores is initially studied. Then, the stepwise reduction behaviors of a composite oxide Mn_1-xFe_xO (0 ≤ x ≤ 1) and hercynite (Mn_1−yFe_yAl₂O₄, 0 ≤ y ≤ 1) were investigated to clarify that Mn-Fe ores have a positive impact on the reduction of fayalite and hercynite in Al-Fe ores. This study reported a simple green route, the carbothermic co-reduction–magnetic separation process, to economically and effectively treat Al-Fe ores and Mn-Fe ores. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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13 pages, 2219 KiB

Open AccessArticle

Application of the Molecular Interaction Volume Model for Calculating Activities of Elements in Ferromanganese Alloys: Mn-C, Mn-Fe, Fe-C, and Mn-Fe-C Systems

by Haipeng Chen, Lihua Gao, Wenlong Zhan, Zhijun He and Junhong Zhang

Crystals 2022, 12(5), 682; https://doi.org/10.3390/cryst12050682 - 9 May 2022

Viewed by 2156

Abstract

The molecular interaction volume model (MIVM) developed by Tao is a fluid-based model derived from statistical thermodynamics and fluid phase equilibria. The MIVM was applied successfully to predict each element’s activity in Mn-based alloys, namely, Mn-C Mn-Fe, and Mn-Fe-C systems. The MIVM calculated [...] Read more.

The molecular interaction volume model (MIVM) developed by Tao is a fluid-based model derived from statistical thermodynamics and fluid phase equilibria. The MIVM was applied successfully to predict each element’s activity in Mn-based alloys, namely, Mn-C Mn-Fe, and Mn-Fe-C systems. The MIVM calculated binary parameters between metals (Fe, Mn) and nonmetal (C) in Mn-Fe-C alloys, confirming a strong interaction between Fe and Mn in Mn-Fe-C alloy. The MIVM indicated that iron has a great influence on the activity of Mn and little effect on the activity of carbon. A significant advantage of MIVM is its ability to explain the experimental phenomenon in the Mn-Fe-C ternary system, whereby the predicted values are in good agreement with the experimental data, showing that this model is reliable, convenient, and economic. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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18 pages, 6992 KiB

Open AccessArticle

A New Route to Upgrading the High-Phosphorus Oolitic Hematite Ore by Sodium Magnetization Roasting-Magnetic Separation-Acid and Alkaline Leaching Process

by Jian Pan, Shenghu Lu, Siwei Li, Deqing Zhu, Zhengqi Guo, Yue Shi and Tao Dong

Minerals 2022, 12(5), 568; https://doi.org/10.3390/min12050568 - 30 Apr 2022

Cited by 11 | Viewed by 2441

Abstract

In this paper, an innovative method is proposed to upgrade iron and remove phosphorus from high-phosphorus oolitic hematite ore by the sodium magnetization roasting–magnetic separation–sulfuric acid and sodium hydroxide leaching process. The process parameters of sodium magnetization roasting, acid leaching, and alkaline leaching [...] Read more.

In this paper, an innovative method is proposed to upgrade iron and remove phosphorus from high-phosphorus oolitic hematite ore by the sodium magnetization roasting–magnetic separation–sulfuric acid and sodium hydroxide leaching process. The process parameters of sodium magnetization roasting, acid leaching, and alkaline leaching were optimized. The results show that by only adopting traditional magnetization roasting–magnetic separation, an iron ore concentrate containing 57.49% Fe and 1.4% P₂O₅ at an iron recovery rate of 87.5% and a dephosphorization rate of 34.27% was produced, indicating that it is difficult to effectively dephosphorize and upgrade iron by the conventional magnetization roasting–magnetic separation process. The obtained rough magnetic concentrates were then subjected to acid and alkaline leaching steps, and the final product, assayed at 64.11% iron and 0.097% P₂O₅, was manufactured successfully. Moreover, the added NaOH could promote the mineral phase reconstruction of aluminum- and silica-bearing minerals during magnetization roasting and intensify the upgrading of iron as well as enhance the growth of iron grains. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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13 pages, 4436 KiB

Open AccessArticle

Phase Transformation and Zinc Extraction from Zinc Ferrite by Calcium Roasting and Ammonia Leaching Process

by Zeqiang Xie, Tao Jiang, Feng Chen, Yufeng Guo, Shuai Wang and Lingzhi Yang

Crystals 2022, 12(5), 641; https://doi.org/10.3390/cryst12050641 - 29 Apr 2022

Cited by 13 | Viewed by 2700

Abstract

Zinc ferrite (ZnFe₂O₄), one of the major forms of zinc in electric arc furnace dust and zinc leaching residue, is very difficult to chemically dissolve in either acidic or alkaline solutions. It is therefore necessary to study the extraction [...] Read more.

Zinc ferrite (ZnFe₂O₄), one of the major forms of zinc in electric arc furnace dust and zinc leaching residue, is very difficult to chemically dissolve in either acidic or alkaline solutions. It is therefore necessary to study the extraction of zinc from zinc ferrite to achieve the full recovery of the zinc resources. In this paper, CaO was used to degrade the structure of zinc ferrite and then the ammonia leaching method was applied to recover zinc. The thermodynamic analysis indicated that the zinc ferrite could react with CaO to form zinc oxide and dicalcium ferrite. The CaO–Fe₂O₃–ZnO phase diagram shows that Ca₂Fe₂O₅ can be in equilibrium with ZnO rather than ZnFe₂O₄ at a higher CaO area. The experimental results indicated that the phase transformation of zinc ferrite, reacted with CaO, to zinc oxide and dicalcium ferrite could be completely achieved with a CaO addition of 2.4:1 (mole ratio). The peaks of zinc ferrite in the X-ray diffraction (XRD) patterns cannot be clearly observed after calcium roasting at 1220 °C for 2 h. The ammonia leaching tests showed that the zinc leaching rate was about 90% under optimal roasting conditions. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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13 pages, 4214 KiB

Open AccessArticle

Multi-Element Imaging of a 1.4 Ga Authigenic Siderite Crystal

by Huajian Wang, Yuntao Ye, Yan Deng, Yuke Liu, Yitong Lyu, Fenglian Zhang, Xiaomei Wang and Shuichang Zhang

Minerals 2021, 11(12), 1395; https://doi.org/10.3390/min11121395 - 9 Dec 2021

Cited by 4 | Viewed by 3758

Abstract

Iron formations (IFs) are traditionally considered to be limited during 1.8−0.8 Ga. However, there are recent reports of siderite-dominated IFs within this time interval, such as the 1.40 Ga Xiamaling IF in North China and the 1.33 Ga Jingtieshan IF in Qilian. To [...] Read more.

Iron formations (IFs) are traditionally considered to be limited during 1.8−0.8 Ga. However, there are recent reports of siderite-dominated IFs within this time interval, such as the 1.40 Ga Xiamaling IF in North China and the 1.33 Ga Jingtieshan IF in Qilian. To further explore the crystallization and formation mechanisms of siderite, an authigenic siderite crystal from the Xiamaling IF was fully scanned using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Multi-element imaging with a spatial resolution of 5 μm revealed an obvious rim structure of the siderite crystal, which might record the crystallization and growth processes. The Al- and Fe-enriched zone in the core of siderite crystal might be an iron-bearing nucleus, and the formation of rim structure was related to the transition from a closed crystallization environment to a semi-closed growth environment. These results, combined with carbon isotope evidence from the siderites and surrounding shales, suggest that vigorous dissimilatory iron reduction that can provide Fe²⁺ and HCO₃⁻ to the pore water is a key factor to form the siderite-dominated Xiamaling IF. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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8 pages, 3208 KiB

Open AccessArticle

Biosynthesis of Silver Nanoparticles by Conyza canadensis and Their Antifungal Activity against Bipolaris maydis

by Yueming Yi, Changjin Wang, Xinxin Cheng, Kechuan Yi, Weidong Huang and Haibing Yu

Crystals 2021, 11(12), 1443; https://doi.org/10.3390/cryst11121443 - 23 Nov 2021

Cited by 8 | Viewed by 2366

Abstract

Silver nanoparticles were biosynthesized from Conyzacanadensis leaf extract with the help of a microwave oven. The UV-vis spectrum showed the maximum absorption at 441 nm, corresponding to the surface plasmon resonance of silver nanoparticles. Transmission electron microscope and scanning electron microscope images [...] Read more.

Silver nanoparticles were biosynthesized from Conyzacanadensis leaf extract with the help of a microwave oven. The UV-vis spectrum showed the maximum absorption at 441 nm, corresponding to the surface plasmon resonance of silver nanoparticles. Transmission electron microscope and scanning electron microscope images showed that the synthesized silver nanoparticles were spherical or near-spherical with an average diameter of 43.9 nm. X-ray diffraction demonstrated nanoparticles with a single-phase cubic structure. As-synthesized silver nanoparticles displayed prominent antifungal activity against Bipolaris maydis. The colony inhibition rate reached 88.6% when the concentration of nanosilver colloid was 100 μL·mL⁻¹ (v/v). At such a concentration, no colony formation was observed on the solid plate. The diameter of the inhibition zone was 13.20 ± 1.12 mm. These results lay the foundation for the comprehensive control of plant pathogens using an environmentally friendly approach. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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13 pages, 5064 KiB

Open AccessArticle

Effects of Specularite on the Preheating and Roasting Characteristics of Fluorine-Bearing Iron Concentrate Pellets

by Shuai Wang, Ying Jiang, Yufeng Guo, Feng Chen and Lingzhi Yang

Crystals 2021, 11(11), 1319; https://doi.org/10.3390/cryst11111319 - 28 Oct 2021

Cited by 1 | Viewed by 1970

Abstract

Fluorine-bearing iron ore is unique and complex. Serious preheating and roasting problems of fluorine-bearing iron concentrate pellets appear during the industrial production by the grate-kiln process. Besides, specularite has low hydrophilicity, undesirable particle size and shape, dense and smooth particle surface and poor [...] Read more.

Fluorine-bearing iron ore is unique and complex. Serious preheating and roasting problems of fluorine-bearing iron concentrate pellets appear during the industrial production by the grate-kiln process. Besides, specularite has low hydrophilicity, undesirable particle size and shape, dense and smooth particle surface and poor assimilation performance. Thus, it has not yet been widely applied in production. This study applied the specularite to improve the preheating and roasting characteristics of the fluorine-bearing iron concentrate pellets. The experiment results indicated that the roasting properties of fluorine-bearing iron concentrate pellets were improved and the compression strength of roasted pellets increased with the addition of 10% specularite. The suitable roasting temperature range was expanded to more than 140 °C. Compared to other addition, the total iron of pellets was also increased. In addition, the improvement mechanism of adding specularite on the properties of fluorine-bearing iron concentrate pellets was discussed. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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11 pages, 2475 KiB

Open AccessArticle

Effect of Humic Acid Binder on Oxidation Roasting of Vanadium–Titanium Magnetite Pellets via Straight-Grate Process

by Yihui Yi, Guanghui Li, Pengxu Cao, Xin Zhang, Yongkang Zhang, Jin Zhang and Jiahao Huang

Crystals 2021, 11(11), 1283; https://doi.org/10.3390/cryst11111283 - 22 Oct 2021

Cited by 3 | Viewed by 1974

Abstract

The oxidation roasting of vanadium–titanium magnetite (VTM) pellets with a new composite binder was investigated using a pilot-scale straight-grate. The evolution of the chemical and phase composition, the compressive strength, and the metallurgical properties of the fired VTM pellets were investigated. Under a [...] Read more.

The oxidation roasting of vanadium–titanium magnetite (VTM) pellets with a new composite binder was investigated using a pilot-scale straight-grate. The evolution of the chemical and phase composition, the compressive strength, and the metallurgical properties of the fired VTM pellets were investigated. Under a preheating temperature of 950

^{\circ}

C, a preheating time of 18 min, a firing temperature of 1300

^{\circ}

C, and a firing time of 10 min, the compressive strength of the fired pellets was as high as 2344 N per pellet. The fired pellets mainly consisted of hematite, pseudobrookite, spinel and olivine. The total iron content of the fired pellets was 0.97% higher using 0.75 wt% humic acid (HA) binder instead of 1.5 wt% bentonite binder. These properties are beneficial for the production efficiency and energy efficiency of their subsequent use in blast furnaces. Moreover, both the softening interval and the softening melting interval of the HA binder pellets were narrower than those of the bentonite binder pellets, conducive to the smooth and successful smelting of the VTM pellets in a blast furnace. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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14 pages, 5217 KiB

Open AccessReview

The Deposit Formation Mechanism in Coal-Fired Rotary Kiln for Iron Ore Pellet Production: A Review

by Shuai Wang, Yufeng Guo, Kuo Liu, Zhuang Yang, Yajing Liu, Ying Jiang, Feng Chen, Fuqiang Zheng and Lingzhi Yang

Crystals 2021, 11(8), 974; https://doi.org/10.3390/cryst11080974 - 17 Aug 2021

Cited by 21 | Viewed by 5085

Abstract

The deposit-forming problem is one of the main bottlenecks restricting the yield and production benefit of iron ore pellets produced by coal-fired rotary kilns. In order to implement measures to ensure the efficient production of pellets by coal-fired rotary kilns, the mechanism and [...] Read more.

The deposit-forming problem is one of the main bottlenecks restricting the yield and production benefit of iron ore pellets produced by coal-fired rotary kilns. In order to implement measures to ensure the efficient production of pellets by coal-fired rotary kilns, the mechanism and influencing factors on the deposit formation were reviewed. The pellet powder and coal ash come together to form the material base of the deposit. Meanwhile, the local reducing atmosphere caused by the continued combustion of residual carbon increases the FeO content, resulting in the formation of low-melting-point silicates. Moreover, alkali metal elements in coal ash can also promote liquid phase formation to cause serious deposit aggregation problems. During high-temperature roasting, the liquid phase corrodes the surface of the refractory brick to form the initial deposit, whereafter, it binds the pellet powder and coal ash from the material layer, which causes the deposit to accumulate continuously. The deposit formation of coal-fired rotary kilns is the result of interaction between many factors, which includes the quality of the green pellets, the composition of coal ash, the combustion efficiency of pulverized coal, roasting temperature, FeO content and alkali metal input. Finally, it is recommended that some measures to mitigate deposit formation can be adopted, such as increasing the compression strength of preheated pellets, choosing high-quality raw materials with low alkali metals, improving the combustion of pulverized coal. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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13 pages, 8782 KiB

Open AccessArticle

Effect of Erosion Behavior of FeO-CaO-SiO₂-MgO-Al₂O₃ Blast Furnace Primary Slag on Al₂O₃ Substrate

by Xiangyang Pan, Fengman Shen, Qiangjian Gao, Xin Jiang and Haiyan Zheng

Crystals 2021, 11(8), 957; https://doi.org/10.3390/cryst11080957 - 16 Aug 2021

Cited by 4 | Viewed by 2860

Abstract

Al₂O₃ substrate is widely used as a lining refractory material throughout the blast furnace (BF) process. Accordingly, the erosion of Al₂O₃ refractory by molten slag has a negative influence on the running cost and smooth operation of [...] Read more.

Al₂O₃ substrate is widely used as a lining refractory material throughout the blast furnace (BF) process. Accordingly, the erosion of Al₂O₃ refractory by molten slag has a negative influence on the running cost and smooth operation of BFs. The effect of the erosion behavior of BF primary slag containing FeO-CaO-SiO₂-MgO-Al₂O₃ on Al₂O₃ substrate refractory was fundamentally investigated using the high-temperature contact angle method and FactSage thermodynamic software based on the composition of BF primary slag in a typical iron and steel enterprise of China. The results showed that the primary slag mentioned above was easily wetted with Al₂O₃ substrate, and the observed contact angles were 24.5° and 22.0°, when the FeO mass fraction (w(FeO)) was maintained at 10% and 15% of the primary slag, respectively. Moreover, the starting melting temperature of the primary slag with high FeO content, of 1263 °C, was lower. The erosion thickness between the slag and Al₂O₃ substrate increased from 19.23 to 23.17 μm as the added w(FeO) increased from 10% to 15%. In addition, it was observed via SEM-EDS analysis that the interface layer was formed, and high-melting-point compounds were generated during the wetting process. This was attributed to the interaction between the molten slag and Al₂O₃ existing in the substrate, which may have inhibited the continuous dissolution of the Al₂O₃ in the substrate into slag. Good surface wettability and the dissolution of the Al₂O₃ substrate refractory into the primary slag of the BF are two dominant factors leading to the erosion of the refractory. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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6 pages, 841 KiB

Open AccessArticle

Pelletizing Analysis on MgO-Fluxed Pellets by DEM

by Fang Long, Fengman Shen, Xin Jiang, Fu Yang, Yulu Zhou and Haiwei An

Crystals 2021, 11(7), 821; https://doi.org/10.3390/cryst11070821 - 15 Jul 2021

Cited by 2 | Viewed by 2335

Abstract

The Discrete Element Method (DEM) was used to analyze the pelletization process of MgO-fluxed pellets. The effects of the charge ratio and rotational speed of the disc pelletizer on the behavior of MgO-fluxed pellets were investigated by using a simulation. The simulation results [...] Read more.

The Discrete Element Method (DEM) was used to analyze the pelletization process of MgO-fluxed pellets. The effects of the charge ratio and rotational speed of the disc pelletizer on the behavior of MgO-fluxed pellets were investigated by using a simulation. The simulation results show that under the condition of a certain tilt angle of the disc pelletizer (the tilt angle is 49°), the suitable parameters of the disc pelletizer are that the charge ratio is 20% and the rotational speedis 0.7 N/NC. This simulation model proposed will be useful to research pellets behavior and for the design of disc pelletizers. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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14 pages, 5493 KiB

Open AccessArticle

Effect of Unburned Pulverized Coal on the Melting Characteristics and Fluidity of Blast Furnace Slag

by Dongwen Xiang, Fengman Shen, Xin Jiang, Qiangjian Gao and Haiyan Zheng

Crystals 2021, 11(6), 579; https://doi.org/10.3390/cryst11060579 - 21 May 2021

Cited by 8 | Viewed by 2601

Abstract

A substantial amount of attention has been paid to viscosity due to its substantial effect on the fluid dynamics of molten blast furnace slag and slag metal reaction kinetics during the pyrometallurgy process. To clarify the influence mechanism of unburned pulverized coal (UPC) [...] Read more.

A substantial amount of attention has been paid to viscosity due to its substantial effect on the fluid dynamics of molten blast furnace slag and slag metal reaction kinetics during the pyrometallurgy process. To clarify the influence mechanism of unburned pulverized coal (UPC) on blast furnace (BF) slag viscosity, the effects of different contents of UPC on the BF slag viscosity, free-running temperature and viscous flow activation energy were investigated. The slag viscosity was measured by the rotating cylinder method, and the microstructure of the cooled slag was observed by SEM. As a result, the main reason for a change in the slag viscosity, free-running temperature and viscous flow activation energy was that the UPC entering the slag formed a large number of white particles that predominantly comprised deposited carbon and a high melting point solid solution. In addition, the disintegration or polymerization of the Si_x

O_{y}^{z -}

structure was also a contributing factor. When the content of the UPC was 0.6%, the free-running temperature and viscous flow activation energy of slag were 1623 K and 120.969 kJ/mol, respectively, which are lower than those of the slag without UPC. However, the free-running temperature and viscous flow activation energy increased to 1668 K and 286.625 kJ/mol, respectively, when the content of UPC increased to 4%, which are higher than those of slag without UPC. Full article

(This article belongs to the Topic Iron Concentrate Particles)

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