High-phosphorus Iron Ore Research Articles

Migration behavior of iron and phosphorus during gas-based reduction for high-phosphorus iron ore

With the depletion of high-grade iron ore, it is necessary to develop low-quality high-phosphorus iron ore through economical and sustainable solutions. In this study, we presented simultaneous enrichment of iron (Fe) and phosphorus (P) to recover P from high-phosphorus iron ore and clarified the migration of P from the original apatite to reduced iron during the direct reduction process. To capture the migration route, gas-based reduction at a relatively slow rate was conducted on two typical iron ores samples (low-grade and high-grade) at different temperatures and times. Results indicate that there are concentration gradients for P and Fe of reaction products in the low-grade iron ore at 1400 °C. The P content continuously increased in the sequence from metallic iron (Fe), wustite (FeO), and fayalite (Fe2SiO4), to apatite (Ca3(PO4)3F). Conversely, the content of Fe gradually decreased. During this process, P dissolved from apatite entered and formed P-bearing fayalite. For the high-grade iron ore, P-bearing fayalite with a metastable structure disappeared as the reduction progressed, and P was released and then reduced to a gaseous state, finally absorbed by metallic iron. Furthermore, when metallic iron was not formed in the initial 60 min at 1300 °C, the P migrated from the apatite to the fayalite and gas phase. As the reduction time increased from 60 min to 240 min, the formed metallic iron provided a site for gasified P, which inhibited the volatilization of P and contributed to Fe and P enrichment.

Clean production of Fe-based amorphous soft magnetic alloys via smelting reduction of high-phosphorus iron ore and apatite

Clean production of Fe-based amorphous soft magnetic alloys via smelting reduction of high-phosphorus iron ore and apatite

Study on Efficient Dephosphorization in Converter Based on Thermodynamic Calculation

Given the accelerating depletion of iron ore resources, there is growing concern within the steel industry regarding the availability of high-phosphorus iron ore. However, it is important to note that the utilization of high-phosphorus iron ore may result in elevated phosphorus content and notable fluctuations in molten iron, thereby imposing additional challenges on the dephosphorization process in steelmaking. The most urgent issue in the process of converter steelmaking is how to achieve efficient dephosphorization. In this study, the influence of various factors on the logarithm of the phosphorus balance distribution ratio (lgLp), the logarithm of the P2O5 activity coefficient (lgγP2O5), and the logarithm of the phosphorus capacity (lgCp) were examined through thermodynamic calculations. The impact of each factor on dephosphorization was analyzed, and the optimal conditions for the dephosphorization stage of the converter were determined. Furthermore, the influence of basicity and FetO content on the form of phosphorus in the slag was analyzed using FactSage 7.2 software, and the precipitation rules of the slag phases were explored. The thermodynamic calculation results indicated that increasing the basicity of the dephosphorization slag was beneficial for dephosphorization, but it should be maintained below 3. The best dephosphorization effect was achieved when the FetO content was around 20%. The reaction temperature during the dephosphorization stage should be kept low, as the dephosphorization efficiency decreased sharply with the increasing temperature. In dephosphorization slag, Ca3(PO4)2 usually formed a solid solution with Ca2SiO4, so the form of phosphorus in the slag was mainly determined by the precipitation form and content of Ca2SiO4. The phases in the dephosphorization slag mainly consisted of a phosphorus-rich phase, an iron-rich phase, and a matrix phase. The results of scanning electron microscopy and X-ray diffraction analyses were consistent with the thermodynamic calculation results.

Preparation of Reduced Iron Powder from High-Phosphorus Iron Ore: A Pilot-Scale Rotary-Kiln Investigation

ABSTRACT Dephosphorization is essential for utilizing high-phosphorus iron ore (HPIO), and this work prepared reduced iron powder via reductive roasting in a semi-industrial rotary kiln follower by magnetic separation. Under the conditions, reductive temperature of 1150°C, duration time of 60 min, mass ratio of briquettes to pea coal of 1:1, the reduced iron powder with an iron grade of 93.21% and phosphorus content of 0.13% was obtained, of which the corresponding iron recovery is 82.68% and dephosphorization ratio is 89.87%. The limestone reacted with gangue to form calcium aluminum silicate, preventing the reduction of phosphorate and in turn the formation of ferrophosphorus.

Gasification Behavior of Phosphorus during Biomass Sintering of High-phosphorus Iron Ore

Developing the innovative technology for efficient utilization of high-phosphate iron ore was the inevitable choice of resource strategy. In this paper, exploring a new method of gasification removal of phosphorus by iron ore sintering technology based on biomass. Combined with theoretical analysis and experimental research, the effects of different conditions (biochar type, addition proportion, basicity) on the reduction and gasification behavior of phosphorus were studied. The results showed that the addition of biochar instead of part of the coke powder could promote the reduction of apatite and increase the dephosphorization rate compared with the full coke breeze. Among different types of biochar fuels (fruit shell charcoal, straw charcoal, bamboo charcoal), bamboo carbon had the greatest effect on the dephosphorization rate. The optimal reduction temperature was 1100°C, substitution proportion of bamboo charcoal was 20% and basicity was 0.5 for the phosphorus gasification and removal, and the corresponding dephosphorization rate was 28.77%. Selective reduction of iron and phosphorus existed in the reduction process, iron oxide took precedence over the reduction of apatite, and part of phosphorus gas entered the metal iron to form iron phosphide, resulting in the decrease of dephosphorization rate.

A novel and clean utilization of converter sludge by co-reduction roasting with high-phosphorus iron ore to produce powdery reduced iron

The efficient and harmless utilization of converter sludge (CS) still faces problems. In the traditional roasting process of high-phosphorus iron ore (HPIO), a large amount of sodium or calcium salt needs to be added to enhance iron recovery and dephosphorization, which leads to an increase in production costs. In this paper, the co-reduction roasting followed by magnetic separation process was designed to realize the full recycling and clean utilization of CS and upgrade HPIO. The results show that the hazardous CS can serve as an ideal admixture in this process which ameliorated the conversion of iron oxides to metallic iron and inhibited the reduction of phosphorus in iron oxides in HPIO. And the element of iron in CS was fully recycled as well. Under optimal conditions, the powdery reduced iron with 93.45% Fe and 0.09% P was produced, which can be a superior substitute for scrap steel in steelmaking, and the iron recovery reached 96.10%. The tailings were cleaned with a leaching toxicity significantly lower than the standard threshold, and the composition indicate that they were excellent raw material for cement production. This novel process realizes the comprehensive and green utilization of CS.

Study on the Effect of Different Factors on the Change of the Phosphorus-Rich Phase in High Phosphorus Steel Slag

With the use of high phosphorus iron ore, there is a large amount of high phosphorus steel slag formed, which is difficult to handle. How to separate the elemental phosphorus has become a key issue in the secondary utilization of steel slag. Experiments found that there were distinct phosphorus-rich phases, iron-rich phases and matrix phases in the high-phosphorus steel slag cooled with the furnace. In this study, the effects of heat treatment conditions and slag basicity on the P2O5 content, as well as the size of the phosphorus-rich phase were investigated. Taking all factors into consideration, the optimal experimental conditions were determined as the holding temperature and time of 1350 °C and 60 min, respectively, and the slag basicity of 1.8. At this time, the P2O5 content in the phosphorus-rich phase reached 24.2%, and the average size of the phosphorus-rich phase was 63.51 μm. The phosphorus-rich phase is separated by crushing and magnetic separation for making phosphate fertilizer, and the residual steel slag is used again for steelmaking, which enables the realization of the resource utilization of high phosphorus steel slag.

Gasification Behavior of Phosphorus during Hydrogen-rich Sintering of High-phosphorus Iron Ore

In order to realize the efficient utilization of high phosphorus iron ore resources, a new method of phosphorus gasification removal in hydrogen-rich sintering process was proposed. In this paper, the gasification behavior of phosphorus in hydrogen-rich sintering process of high-phosphorus iron ore was studied. Thermodynamic calculation of possible reactions is carried out by using FactSage6.1 software, and the phase transformation and distribution of phosphorus in the process of roasting reduction were analyzed by XRD, SEM-EDS and EPMA. The experimental results show that in hydrogen-rich atmosphere, the dephosphorization rate increased from 9.9% to 29.51% and then decreased to 8.62% in the temperature range of 900°C–1200°C, and the maximum value appeared at 1100°C. Compared to the carbon reduction, the dephosphorization rate in hydrogen-rich atmosphere increased significantly in the whole temperature range, and the maximal dephosphorization rate could be improved from 15.03% to 29.51%. The results of thermodynamic analysis showed that the initial temperature of direct reduction of apatite by hydrogen is higher, and adding SiO2 and Na2CO3 allowed to decrease the reduction temperature of apatite by hydrogen to about 946.50°C. With the increase of reduction temperature, the reduced phosphorus gas was absorbed by metallic iron to form stable iron phosphorus compounds, resulting in the decrease of dephosphorization rate. Therefore, in order to realize the gasification removal of phosphorus, the selective reduction of iron oxide and apatite should be realized, and the formation of liquid iron should be avoided as far as possible in the reduction process.

Effect of calcium compounds on direct reduction and phosphorus removal of high-phosphorus iron ore

Effect of calcium compounds on direct reduction and phosphorus removal of high-phosphorus iron ore

Effect of additives on iron recovery and dephosphorization by reduction roasting-magnetic separation of refractory high-phosphorus iron ore

Effect of additives on iron recovery and dephosphorization by reduction roasting-magnetic separation of refractory high-phosphorus iron ore

Application of a fungal cellulase as a green depressant of hematite in the reverse anionic flotation of a high-phosphorus iron ore

In this study, a fungal cellulase enzyme was applied to improve the selective separation of apatite from hematite during the reverse anionic flotation of a high-phosphorus iron ore. Bench-scale flotation tests were conducted on pure hematite and apatite minerals, their artificial mixture, and a high-phosphorus iron ore sample, using oleic acid as a collector. Flotation tests on single minerals showed that cellulase was a good depressant of hematite, but had no depressing effect on apatite at pH 10. The phosphorus content in the concentrate product of the flotation of artificially mixed pure minerals was reduced from 1.96% to 0.03%, with iron grade and recovery of 64.15% and 94.74%, respectively, using 4x10−5 mol/L oleate and 0.02% cellulase at pH 10. By applying the optimum separation conditions to the flotation of a natural high-phosphorus iron ore, the phosphorus content in the concentrate was reduced from 0.84% to 0.19% at an iron recovery of 67.85%. The mechanism of the cellulase depressing effect was investigated through Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses. The results showed that cellulase enzyme was adsorbed on the surfaces of both minerals; however, the depressing effect was significant in case of hematite but not apatite. This might be attributed to the coverage of apatite surface with a close-packed layer of oleate molecules, which made the surface of apatite hydrophobic enough to counter the polarity induced upon cellulase adsorption.

A novel direct reduction-flash smelting separation process of treating high phosphorous iron ore fines

Phosphorus (P) is one of the most deleterious elements in iron ore, it is easy to form iron phosphides that make steel brittle during reduction processes. A new process (direct reduction and flash smelting separation (FSS)) of treating high phosphorus iron ore (HPIO) is introduced in this paper. By limiting the smelting separation between slag and iron to the level of about 1 s, the reduction and migration process of P element was restrained, and the content of P element in the metallic iron obtained after separation was limited to about 0.3 wt%. The effects of flash smelting temperature and ore particle size on the flash smelting process were studied. The migration process of phosphorus was analyzed, and a mathematical model of this smelting process was established to facilitate the visualized understanding and regulation of this process.

Technological Challenges of Phosphorus Removal in High-Phosphorus Ores: Sustainability Implications and Possibilities for Greener Ore Processing

With the present rates of iron ore consumption, currently unusable, high-phosphorus iron ore deposits are likely to be the iron ores of the future as higher-grade iron ore reserves are depleted. Consequently, the design and timely development of environmentally-benign processes for the simultaneous beneficiation of high-phosphorus iron ores and phosphorus recovery, currently a technological challenge, might soon become a sustainability challenge. To stimulate interest in this area, phosphorus adsorption and association in iron oxides/hydroxyoxides, and current efforts at its removal, have been reviewed. The important properties of the most relevant crystalline phosphate phases in iron ores are highlighted, and insights provided on plausible routes for the development of sustainable phosphorus recovery solutions from high-phosphorus iron ores. Leveraging literature information from geochemical investigations into phosphorus distribution, speciation, and mobility in various natural systems, key knowledge gaps that are vital for the development of sustainable phosphorus removal/recovery strategies and important factors (white spaces) not yet adequately taken into consideration in current phosphorus removal/recovery solutions are highlighted, and the need for their integration in the development of future phosphorus removal/recovery solutions, as well as their plausible impacts on phosphorus removal/recovery, are put into perspective.

Beneficiation of Low-Grade and High-Phosphorus Iron Ore of Bajrawia, Sudan by Reverse Anionic Flotation: Potential of Microwave Treatment

Deposits of low grade and high-phosphorus iron ores are spreading globally, however, the usage of this kind of deposits in the manufacturing of steel bounded because of the high-phosphorus content as well as depression of iron in which affect the quality of the produced steel. The Bajrawia iron ore deposit is one of the largest in Sudan but it only contains (35.5% Fe) and undesirable amount of phosphorus (0.37% P). This paper investigated the utilization of reverse anionic flotation (RAF) for the upgrading of iron and dephosphorization. Additionally, the effect of microwave pre-treatment on forth flotation performance on a laboratory scale. Microwave pre-treatment was applied on optimized reverse anionic flotation parameters in an account of iron grade (47.31% Fe), iron recovery (86.43%) and phosphorus content (0.167% P). The findings into the microwave pre-treatment are quite promising. This investigation has revealed that microwave heating improves the flotation response of iron grade to (51.94%) and phosphorus content decreases into (0.127% P) due to increasing the liberation.

Removal of Phosphorus from High-phosphorus Iron Ore with Preliminary Reduction Treatment and Physical Concentration

Removal of Phosphorus from High-phosphorus Iron Ore with Preliminary Reduction Treatment and Physical Concentration

Removal of Phosphorus from High-phosphorus Iron Ore with Preliminary Reduction Treatment and Physical Concentration

Removal of Phosphorus from High-phosphorus Iron Ore with Preliminary Reduction Treatment and Physical Concentration

Reduction Characteristics of High Phosphorus Iron Ore in Reducing Parameters Similar to Blast Furnace Conditions

The strong global demand for iron and steel has necessitated the utilization of various low grade iron ores, which are not suitable for direct utilization in ironmaking processes. The low grade iron ores cannot be dressed effectively using the traditional mineral processing methods because of complicated min-eral compositions. The main problem associated with exploiting these deposits is the dissemination of fine silicate minerals and the high level of phosphorus content due to the poor liberation of iron minerals from the gangues. The pre-sent manuscript is aimed to investigate reduction properties of iron ores rich in phosphorous in order to study the suitability of using these ores in iron blast furnace. Representative technological samples of iron ore are collected from Eastern South Aswan iron ore mine in Egypt. The principal gangue contents are SiO2 7.76%, and P2O5 1.13%. Iron and phosphorus exist in the form of hematite 78% and apatite respectively. The ore was fired at 1000°C for 3 hours. The green and fired samples were isothermally reduced at conditions which closely represent the theoretical reduction conditions in different zones of blast furnace. The influence of reduction conditions on the reduction behaviour and the morphology of the reduced samples were investigated. After reduction apatite is changed to Calcium phosphate beside fayalite and quartz. The reduction rate of fired samples is greater than that for the green ones and that was confirmed by morphological examination. At cohesive zone condition, the effect of firing on reduction characteristics cannot be distinguished.

Gasification and Migration of Phosphorus from High-phosphorus Iron Ore during Carbothermal Reduction

Gasification and Migration of Phosphorus from High-phosphorus Iron Ore during Carbothermal Reduction

Research on Reaction Mechanism of Vacuum Carbon Thermal Reduction and Dephosphorization in High Phosphate Iron Ore

According to the mineral composition characteristics of high-phosphorus iron ore, the reaction mechanism of fluorapatite was investigated using pure substance and gangue under vacuum carbon thermal reduction (VCTR) conditions. The effects of reduction temperature, basicity, and C/O ratio on the metallization ratio, dephosphorization ratio, and phosphorus content of pellets were studied. The reaction process of fluorapatite in high-phosphorus iron ore was investigated. The results showed that when the metallization ratio of pellets reached maximum (95%), the dephosphorization ratio was only 5.6%, thus indicating adverse result. The reduction processes of high-phosphorus iron ore under vacuum and nitrogen environment were, respectively, compared under the optimal condition. It was found that the metallization ratio of pellets in the vacuum condition was higher than that under the nitrogen condition, while the dephosphorization ratio showed an opposite result. This indicated that in the process of vacuum reduction, fluorapatite not only reacted with carbon to form gaseous phosphide, but also with iron to form compounds containing the Fe–P bond. Therefore, a new mechanism of reduction of fluorapatite was proposed as follows: 2Ca5(PO4)3F + 12Fe + 9SiO2 + 15C = 9CaSiO3 + 6Fe2P + 15CO + CaF2.

Removal of Phosphorus from High Phosphorus Iron Ores in Wushan Mountain by Crosscurrent Acid Leaching

In the process of resource utilization of high phosphorus iron ores, phosphorus should be removed first. Compared to other dephosphorization methods, selective leaching with acid has special advantages such as high dephosphorization ratio, low iron loss and so on. However, a large amount of acidic wastewater containing phosphorus was produced after acid leaching. Therefore, the rational use of acidic wastewater and decrease of acid consumption is crucial to remove phosphorus by acid leaching. In this paper, the thermodynamics of the acid leaching was studied according to the existence form of mineral constituents in high phosphorus iron ores from Wushan Mountain. Then, crosscurrent acid leaching was employed to remove phosphorus from high phosphorus iron ores in Wushan Mountain and the changes in dephosphorization ratio, iron loss and acid concentration was observed during the leaching. The results showed that the phosphorus in Wushan iron ores could be removed selectively by acid leaching. After three-stage crosscurrent leaching, the dephosphorization ratio exceeded 74% and the iron loss was under 2.1%. Meanwhile, the acid concentration was decreased to 0.65mol/l in leaching solution, which could be returned to selective leaching after precipitation of phosphorus and supplement of hydrochloric acid.