High Phosphorus Oolitic Iron Ore Research Articles

Calcium Carbonate as Dephosphorization Agent in Direct Reduction Roasting of High-Phosphorus Oolitic Iron Ore: Reaction Behavior, Iron Recovery, and Dephosphorization Mechanism

Calcium carbonate, renowned for its affordability and potent dephosphorization capabilities, finds widespread use as a dephosphorization agent in the direct reduction roasting of high-phosphorus oolitic hematite (HPOIO). However, its precise impact on iron recovery and the dephosphorization of iron minerals with phosphorus within HPOIO, particularly the mineral transformation rule and dephosphorization mechanism, remains inadequately understood. This study delves into the nuanced effects of calcium carbonate on iron recovery and dephosphorization through direct reduction roasting and magnetic separation. A direct reduction iron (DRI) boasting 95.57% iron content, 93.94% iron recovery, 0.08% phosphorus content, and an impressive 92.08% dephosphorization is achieved. This study underscores how the addition of calcium carbonate facilitates the generation of apatite from phosphorus in iron minerals and catalyzes the formation of gehlenite by reacting with silicon dioxide and alumina, inhibiting apatite reduction. Furthermore, it increases the liquid phase, enhancing the dissociation of metallic iron monomers during the grinding procedure, thus facilitating efficient dephosphorization.

Modulating Fe/P ratios in Fe-P alloy through smelting reduction for long-term electrocatalytic overall water splitting

Owing to strong Fe-P interaction that differs the electron distribution beneath metal/phosphide interface of Fe-P alloy, the charge transfer of Fe-P alloy has been accelerated during the electrocatalytic oxidation process and improved the efficiency and durability of overall water splitting. In this work, a novel metallurgical technology in combination with smelting reduction and Single Roller Melting Spinning (SRMS) for the purpose of electrochemical overall water splitting where High-phosphorus Oolitic Iron Ore (HPOIO) has been directly used as the main raw material is developed for preparing amorphous Fe-P alloys strips. The rational modulation on the Fe/P ratio can alter the crystal structure and crystallinity of Fe-P alloy, favor electron transfer, and further trap the positively charged H+. The obtained FeP electrocatalyst exhibits 436 and 527 mV at 10 mA cm−1 with Tafel slopes of 102.3 and 77.2 mV dec−1 for HER and OER in 1.0 mol/L KOH solution, respectively, especially with long-term stability (∼207 h for HER and ∼42 h for OER). Specifically, the DFT calculation displaying structural advantages and componential superiorities exhibited that P in Fe-P amorphous alloy regulated by systematic P addition optimization might increase the energy density in the Fermi level. Furthermore, the phosphorus content brought about high active surface areas, low impedance, and variable reaction paths-caused low reaction energy barriers with the improved amorphicity and absorption and desorption of intermediates, thereby boosting the overall water splitting activity. This study displays a novel strategy to develop Fe-P amorphous alloy for the stable and efficient overall water splitting.

Green and efficient separation of iron and phosphorus from high-phosphorus oolitic iron ore by reduction roasting without a dephosphorization agent

To provide a new method for the dephosphorization of high-phosphorus oolitic iron ore (HPOIO) by reduction roasting, the feasibility of the high-efficiency separation of iron and phosphorus by reduction roasting and magnetic separation process (RRMSP) without a dephosphorization agent was studied. The results showed that the full separation of iron and phosphorus was achieved without a dephosphorization agent. Under optimal conditions, powdery reduced iron (PRI) with 92.77% iron and 0.09% phosphorus content was produced. Iron recovery and dephosphorization reached 68.70% and 93.50%, respectively. In a weak reducing atmosphere, apatite was not reduced. A portion of the phosphorus in the iron minerals formed apatite, and the remaining phosphorus entered fayalite. Metallic iron and phosphorus minerals were physically separated. Compared with the addition of dephosphorization agent, clean production was realized without the addition of dephosphorization agent, but the iron recovery was not ideal; the economic benefits should be further studied in the future.

A new way to efficient utilization of eggshell waste: As green dephosphorization agent and accelerator for reduction roasting of high-phosphorus oolitic iron ore

The cleaning and efficient disposal of eggshell waste presents many challenges. Reduction roasting of high-phosphorus oolitic iron ore (HPOIO) requires the addition of expensive alkali metal compounds to enhance dephosphorization. In this paper, the eggshell waste from the catering industry was used to replace traditional dephosphorization agents, which not only avoided environmental problems caused by mining, but also improved dephosphorization and iron extraction, and reduced production costs. Under suitable conditions, powdery reduced iron (PRI) comprising 93.04% iron and 0.09% phosphorus was produced. PRI is a premium steelmaking feedstock with 93.11% iron recovery. Mechanism research shows that an appropriate eggshell waste dosage inhibited the reduction of apatite in HPOIO, reacted with phosphorus in iron minerals to form apatite, and promoted the metallization of iron. Moreover, compared with blast furnace ironmaking, this process significantly reduced carbon emissions. It provides a new idea for the green utilization of eggshell waste.

A new iron recovery and dephosphorization approach from high‑phosphorus oolitic iron ore via oxidation roasting-gas-based reduction and magnetic separation process

Deep dephosphorization of high‑phosphorus oolitic iron ore (HPOIO) is extremely difficult because of its refractory characteristics. A new approach for simultaneous iron recovery and dephosphorization from HPOIO by oxidation roasting–gas-based reduction (ORGR) and magnetic separation process was developed. The underlying mechanism was investigated using thermodynamic calculations, X-ray diffraction (XRD), and scanning electron microscopy combined with energy dispersive spectroscopy (SEM–EDS). The results showed that the powdery reduced iron produced contained 91.37% iron and 0.14% phosphorus, and the iron recovery was 92.81%, which is an ideal for steelmaking. The addition of Na2CO3 formed nepheline, which promoted the formation and coarsening of hematite during oxidation. Concurrently, Na2CO3 reacted with the phosphorus in the iron minerals and fluorapatite to form sodium calcium phosphate, which was embedded in hematite with a simple relationship. Hematite was subsequently converted into metallic iron, sodium calcium phosphate was not reduced, and metallic iron and phosphorus were separated efficiently.

Resource-saving production of Fe-based amorphous alloys from carbothermal reduction of high-phosphorus oolitic iron ore

Energy-saving and resource-friendly production of Fe-based soft-magnetic materials is of paramount importance for the development of green economy. In this study, an innovative process for fabricating Fe-based amorphous alloys from high-phosphorus oolitic iron ore was developed with the combination of ironmaking and melt-spinning techniques. By using the developed process, iron and phosphorus in high-phosphorus oolitic iron ore can be simultaneously utilized. During the direct carbothermal reduction process of high-phosphorus oolitic iron ore, oolitic hematite and apatite were first reduced to form liquid iron phase and absorb P2 gas, resulting in the enrichment of P element in iron phase. Fe-P alloys with different P and C content can be easily obtained by tailoring the C/O ratio. The reduced Fe-P alloys with high εFe of 96.4% and εP of 70.7% are ideal raw materials for preparing Fe-based soft-magnetic alloys. Fe80P10C9Si1 amorphous alloy was successfully obtained after composition adjustment. The high AFA of rod sample with diameter up to 1 mm and good magnetic softness of the ribbon samples including high Bs of 1.54 T, low Hc of 3.6 A/m, high μe of 30 × 103 with excellent frequency stability prove the effectiveness of the designed process. These findings are of great significance to lay the foundation for the recycling of resources and preparation of high performance soft-magnetic alloys from iron ores.

Fe-based amorphous alloys with superior soft-magnetic properties prepared via smelting reduction of high-phosphorus oolitic iron ore

Fe-based amorphous alloys generally suffer from the impurities in industrial raw materials and the high cost of pure raw materials. In this work, a revolutionary way for preparing Fe-based amorphous alloys from the refractory high-phosphorus oolitic iron ore with the combination of smelting reduction and melt-spinning was proposed for the simultaneously utilization of Fe and P elements. By using the smelting reduction, Fe–P alloys with high Fe and P recovery rate of 99% and 92% can be obtained, and the C content in the resultant Fe–P alloys can be accurately tailored by adjusting the C/O ratio. For the implementation of the developed process, the reduced Fe–P alloys with significantly different C content and the corresponding Fe83P3C1Si2B11, Fe76P5C3.8Si5.7B9.5 and Fe80P10C9Si1 (at. %) amorphous alloys with close C content were chosen. These resultant alloys all exhibit high AFA, low Hc and high μe as well as wide annealing window comparable to that of the alloys prepared with pure raw materials, demonstrating the feasibility of the developed process for energy-saving and resource-friendly production of soft-magnetic materials via smelting reduction of iron ores.

Influence of Sodium Salts on Reduction Roasting of High-Phosphorus Oolitic Iron Ore

ABSTRACT The reduction roasting followed by magnetic separation process is considered to be a suitable method to treat the high-phosphorus oolitic iron ore. Currently, the dephosphorization mechanism of additives such as CaCO3, Ca(OH)2, Na2SO4, and Na2CO3 on the reduction roasting of the iron ore in which phosphorus occurs in apatite have been thoroughly studied. The effect of sodium salts (Na2CO3, NaCl and Na2SO4) on reduction roasting and magnetic separation of high-phosphorus oolitic iron ore containing phosphorus in iron oxides was investigated, and the mechanisms of sodium salts were expounded using XRD and SEM-EDS. The results show that the dephosphorization ability of sodium salts was in the order of Na2SO4> Na2CO3> NaCl>no sodium salts. Na2CO3 and Na2SO4 transferred Fe3PO7 from the iron oxides to nepheline, which upgraded the separation of iron and phosphorus. However, NaCl did not inhibit the reduction of phosphorus in the iron minerals. In addition, Na2CO3 strengthened the reduction of iron oxides. However, a small amount of wustite failed to be reduced to metallic iron with the addition of NaCl, and troilite and wustite formed hindered the reduction of iron minerals after adding Na2SO4.

The mechanism of CaCO3 in the gas-based direct reduction of a high-phosphorus oolitic iron ore

The mechanism of CaCO3 in the gas-based direct reduction of a high-phosphorus oolitic iron ore

Recovery of iron and phosphorus removal from Gara Djebilet iron ore (Algeria)

Purpose. This research aims to promote the assay of iron and reduce the phosphorus grade of the final DRI. Methodology. A high-phosphorus oolitic iron ore from Gara Djebilet deposit underwent the procedure of coal-based direct reduction (coal-based DR) followed by wet low-intensity magnetic separation (WLIMS). The effects of temperature, periods of time and Na2SO4 dosage on phosphorus removal, metallisation degree and iron recovery rate were tried and optimised. Furthermore, phase changes in iron oxides and the distributing features of phosphorus in both reduced and magnetic materials were investigated as well. Findings. The appropriate addition of sodium sulfate improves the Fe-P separation during the coal-based DR of Gara Djebilet mixed pellets. Originality. Using additives of CaO and sodium sulfate during the coal-based DR-magnetic separation of mixed pellets sourced from Gara Djebilet deposit. Practical value. The results reveal that a final direct reduced powder (DRI) assaying 96 wt% Fe and 0.16 wt% P at a recovery rate of 97.72% was obtained when the ore-coal-CaO mixed pellets were reduced in the presence of 5 wt% Na2SO4 at 1250 C for 30 min. Thus, the coal-based DR could be used as an alternative to the blast furnace (BF) route in the steelmaking industry from refractory iron ores.

Studying on mineralogical characteristics of a refractory high-phosphorous oolitic iron ore

In this study, a high-phosphorus oolitic iron ore containing 44.70% Fe and 1.56% P from western Hubei of China was collected as the sample. The chemical composition, mineral composition, structure characteristics, dissemination characteristics, and iron and phosphorus occurrence state were carried out to investigate the mineralogical characteristics of the high-phosphorus oolitic iron. The results show that the high-phosphorus oolitic iron ore is a chemical sedimentary iron ore, mainly composed of oolite (more than 60%). Specifically, the ooids consists of oolite nuclei, collophanite girdles, and hematite and limonite girdles; the detritus is composed of fine-grained hematite and quartz feldspar; and cement is composed of carbonate minerals and worm-like hematite. The iron concentrate consists of iron-rich oolite and some hematite. The iron-bearing minerals in the oolite are mainly hematite, limonite, chlorite, and collophanite, and a close relationship between the hematite-limonite in the oolites and the iron-containing chamoisite can be observed. Upgrading iron and removing phosphorus from the high-phosphorus oolitic iron ore will be difficult by physical beneficiation.

Migration behaviors and kinetics of phosphorus during coal-based reduction of high-phosphorus oolitic iron ore

To understand the migration mechanisms of phosphorus (P) during coal-based reduction, a high-phosphorus oolitic iron ore was reduced by coal under various experimental conditions. The migration characteristics and kinetics of P were investigated by a field-emission electron probe microanalyzer (FE-EPMA) and using the basic principle of solid phase mass transfer, respectively. Experimental results showed that the P transferred from the slag to the metallic phase during reduction, and the migration process could be divided into three stages: phosphorus diffusing from the slag to the metallic interface, the formation of Fe-P compounds at the slag-metal interface and P diffusing from the slag-metal interface to the metallic interior. The reduction time and temperature significantly influenced the phosphorus content of the metallic and slag phases. The P content of the metallic phase increased with increasing reduction time and temperature, while that of the slag phase gradually decreased. The P diffusion constant and activation energy were determined and a migration kinetics model of P in coal-based reduction was proposed. P diffusion in the metallic phase was the controlling step of the P migration.

Increasing Iron and Reducing Phosphorus Grades of Magnetic-Roasted High-Phosphorus Oolitic Iron Ore by Low-Intensity Magnetic Separation–Reverse Flotation

High-phosphorus oolitic iron ore, treated by suspended flash magnetic roasting, contained 42.73% iron (mainly present as magnetite) and 0.93% phosphorus (present as collophane). Low-intensity magnetic separation (LIMS) was combined with reverse flotation to increase the iron and reduce the phosphorus contents of the roasted product. The results showed that an optimized iron ore concentrate with an iron grade of 67.54%, phosphorus content of 0.11%, and iron recovery of 78.99% were obtained under LIMS conditions that employed a grind of 95% −0.038 mm and a magnetic field of 0.10 T. Optimized rougher reverse-flotation conditions used a pulp pH of 9 and dosages of toluenesulfonamide, starch, and pine alcohol oil of 800 g/t, 1000 g/t, and 40 g/t, respectively; optimized scavenging conditions used a pulp pH of 9 and dosages of toluenesulfonamide, starch, and pine alcohol oil of 400 g/t, 500 g/t, and 20 g/t, respectively. Study of the mechanism of phosphorus reduction showed that the toluenesulfonamide could be adsorbed on the surface of quartz after the action of starch, but adsorption was significantly weakened. The starch inhibitor negatively affected adsorption on quartz, but positively influenced adsorption of phosphorus minerals.

Upgrading iron and removing phosphorus of high phosphorus oolitic iron ore by segregation roasting with calcium chloride and calcium hypochlorite

The iron-bearing ore, existing in the form of oolite, was mainly composed of hematite, limonite, daphnite, and collophane. The harmful element phosphorus content was 1.56%, belonging to high phosphorus ooliticiron ore in western Hubei. In this study, segregation roasting and low intensity magnetic separation techniques were applied for upgrading iron and removing phosphorus. The ores, the chlorinating agent, and the reducing agent were mixed into the roasting furnace for segregation roasting. After being transferred from the weak magnetic minerals to the strong ones, the iron was recovered by low intensity magnetic separation. During segregation roasting, new ore phases, metallic iron (Fe), a small amount of ferroferric oxide (Fe3O4), and ferrous oxide (FeO) could be observed. The results showed that the iron concentrate with the Fe content of 90.3%, the phosphorus content of 0.15%, and the iron recovery of 92.9% were obtained under the segregation roasting temperature of 1273 K, and the roasting time of 90 min, CaCl2 (calcium chloride) 20%, Ca (ClO)2 (calcium hypochlorite) 3%, the dosage of coke 20%, and low intensity magnetic separation field intensity 0.12 T.

Simultaneous Recovery of Iron and Phosphorus from a High-Phosphorus Oolitic Iron Ore to Prepare Fe-P Alloy for High-Phosphorus Steel Production

Unlike previous dephosphorization studies, the present work complies with a concept to recover phosphorus within the utilization of high-phosphorus oolitic iron ores to prepare Fe-P alloy for high-phosphorus steel production. Simultaneous enrichment of iron and phosphorus can be achieved by directly alloying the high-phosphorus oolitic iron ore at high reduction temperatures (≥1623 K). Neither fluxes nor other special additives need to be used. Consequently, the phosphorus element migrates from original apatite to the slag phase with the elevating temperature from 1323 K to 1473 K, and it further moves into metallic iron and forms Fe3P at 1623 K. A metalized iron-phosphorus alloy with assaying of 96.51% iron and 2.03% phosphorus content was obtained at 1623 K for 10 min at corresponding iron and phosphorus recovery rates of 97.50% and 64.51%, respectively. This process exhibits high economic efficiency and is practicable as a stepping-stone for the efficient and direct utilization of high-phosphorus iron ore resources.

Thermodynamic analysis of the carbothermic reduction of a high-phosphorus oolitic iron ore by FactSage

A thermodynamic analysis of the carbothermic reduction of high-phosphorus oolitic iron ore (HPOIO) was conducted by the FactSage thermochemical software. The effects of temperature, C/O ratio, additive types, and dosages both on the reduction of fluorapatite and the formation of liquid slag were studied. The results show that the minimum thermodynamic reduction temperature of fluorapatite by carbon decreases to about 850°C, which is mainly ascribed to the presence of SiO2, Al2O3, and Fe. The reduction rate of fluorapatite increases and the amount of liquid slag decreases with the rise of C/O ratio. The reduction of fluorapatite is hindered by the addition of CaO and Na2CO3, thereby allowing the selective reduction of iron oxides upon controlled C/O ratio. The thermodynamic results obtain in the present work are in good agreement with the experimental results available in the literatures.

Mineralogy, geochemistry and the origin of high-phosphorus oolitic iron ores of Aswan, Egypt

The Coniacian-Santonian high-phosphorus oolitic iron ore at Aswan area is one of the major iron ore deposits in Egypt. However, there are no reports on its geochemistry, which includes trace and rare earth elements evaluation. Texture, mineralogy and origin of phosphorus that represents the main impurity in these ore deposits have not been discussed in previous studies. In this investigation, iron ores from three localities were subjected to petrographic, mineralogical and geochemical analyses. The Aswan oolitic iron ores consist of uniform size ooids with snowball-like texture and tangentially arranged laminae of hematite and chamosite. The ores also possess detrital quartz, apatite and fine-grained ferruginous chamosite groundmass. In addition to Fe2O3, the studied iron ores show relatively high contents of SiO2 and Al2O3 due to the abundance of quartz and chamosite. P2O5 ranges from 0.3 to 3.4wt.% showing strong positive correlation with CaO and suggesting the occurrence of P mainly as apatite. X-ray diffraction analysis confirmed the occurrence of this apatite as hydroxyapatite. Under the optical microscope and scanning electron microscope, hydroxyapatite occurred as massive and structureless grains of undefined outlines and variable size (5–150μm) inside the ooids and/or in the ferruginous groundmass. Among trace elements, V, Ba, Sr, Co, Zr, Y, Ni, Zn, and Cu occurred in relatively high concentrations (62–240ppm) in comparison to other trace elements. Most of these trace elements exhibit positive correlations with SiO2, Al2O3, and TiO2 suggesting their occurrence in the detrital fraction which includes the clay minerals. ΣREE ranges between 129.5 and 617ppm with strong positive correlations with P2O5 indicating the occurrence of REE in the apatite. Chondrite-normalized REE patterns showed LREE enrichment over HREE ((La/Yb)N=2.3–5.4) and negative Eu anomalies (Eu/Eu*=0.75–0.89). The oolitic texture of the studied ores forms as direct precipitation of iron-rich minerals from sea water in open space near the sediment-water interface by accretion of FeO, SiO2, and Al2O3 around suspended solid particles such as quartz and parts of broken ooliths. The fairly uniform size of the ooids reflects sorting due to the current action. The geochemistry of major and trace elements in the ores reflects their hydrogenous origin. The oolitic iron ores of the Timsha Formation represent a transgressive phase of the Tethys into southern Egypt during the Coniacian-Santonian between the non-marine Turonian Abu Agag and Santonian-Campanian Um Barmil formations. The abundance of detrital quartz, positive correlations between trace elements and TiO2 and Al2O3, and the abundance mudstone intervals within the iron ores supports the detrital source of Fe. This prediction is due to the weathering of adjacent land masses from Cambrian to late Cretaceous. The texture of the apatite and the REE patterns, which occurs entirely in the apatite, exhibits a pattern similar to those in the granite, thus suggesting a detrital origin of the hydroxyapatite that was probably derived from the Precambrian igneous rocks. Determining the mode of occurrence and grain size of hydroxyapatite assists in the maximum utilization of both physical and biological separation of apatite from the Aswan iron ores, and hence encourages the use of these ores as raw materials in the iron making industry.

Separation of P Phase and Fe Phase in High Phosphorus Oolitic Iron Ore by Ultrafine Grinding and Gaseous Reduction in a Rotary Furnace

Due to the oolitic structure of the high phosphorus iron ore and the closely wrapping of apatite and hematite phases, an approach using jet mill was utilized to grind the ore to ultrafine 0.01 to 0.001 mm, which realizes the dissociation of apatite phase and hematite phase. Then in a laboratory scale rotary furnace, high phosphorus ores of different sizes were reduced by reducing gas at sub-melting point temperatures (973 to 1173 K [700 to 900 °C]). In the rotating inclined reactor, the ore particles reacted with the reducing gas coming from the opposite direction in a rolling and discrete state, which greatly improved the kinetic conditions. In this study, the reaction rate increases significantly with the decrease of particle size. For the ultrafine high phosphorus iron ores, the metallization ratio can reach 83.91 to 97.32 pct, but only 33.24 to 40.22 pct for powders with the size of 0.13 to 0.15 mm. The reduced particles maintained their original sizes, without the presence of sintering phenomenon or iron whisker. Hence, two kinds of products were easily obtained by magnetic separation: the iron product with 91.42 wt pct of Fe and 0.19 wt pct of P, and the gangue product with 13.77 wt pct of Fe and 2.32 wt pct of P.

Phosphorus Removal of High Phosphorous Oolitic Iron Ore with Acid-Leaching Fluidized-Reduction and Melt-Separation Process

A process with acid leaching followed by hydrogen-based fluidized reduction and melt separation is presented for recovering DRI (direct reduced iron) from high-phosphorus oolitic hematite in this study, and the aim of this study is to provide theoretical and technical basis for economical and rational use of high phosphorus oolitic iron ores. The reducibility of the ore can be improved by acid leaching, which is caused by the formation of voids in the ore particles after acid leaching and enhancing the internal gas diffusion. The phosphorus content in the DRI is still relative high even though there is no carbon in DRI, and it can be decreased to 0.087 wt% (raw ore 1.2 wt%) with the optimum condition in this study. It is proved that P exists in the DRI recovered from melt separation in the form of P2O5 inclusions or FexP as solid solutions, while not in the form of Ca3(PO4)2 inclusions. Finally, a combined flowsheet for the treatment of high phosphorus oolitic iron ore is designed in this study.

Can sodium sulfate be used as an additive for the reduction roasting of high-phosphorus oolitic hematite ore?

A process of coal-based direct reduction roasting followed by magnetic separation was used to produce direct reduction iron (DRI) from high-phosphorus oolitic iron ore. The effect of sodium sulfate, which was used as an additive in the roasting process, was investigated. The addition of sodium sulfate increased the iron content and reduced the phosphorus content of DRI, but a sharp increase in the sulfur content of the DRI was observed. Although the S content of the DRI can be reduced to some extent by increasing roasting time as well as improving roasting temperature, its level is still too high for steelmaking. The results of scanning electron microscopy and energy-dispersive spectroscopy showed that when sodium sulfate was added, FeS was generated in the reduced briquette. FeS was intimately intermixed with metallic iron, which was difficult to remove. Therefore, sodium sulfate was not a suitable additive for the reduction of high-phosphorus oolitic hematite ore.