High-phosphorus Oolitic Hematite Ore Research Articles

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

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.

Synchronous enrichment of phosphorus and iron from a high-phosphorus oolitic hematite ore to prepare Fe-P alloy by direct reduction-magnetic separation process

Synchronous enrichment of phosphorus and iron from a high-phosphorus oolitic hematite ore to prepare Fe-P alloy by direct reduction-magnetic separation process

Effects of CaCO<sub>3</sub> as Additive on Coal-based Reduction of High-phosphorus Oolitic Hematite Ore

Effects of CaCO<sub>3</sub> as Additive on Coal-based Reduction of High-phosphorus Oolitic Hematite Ore

Direct Reduction of High-phosphorus Oolitic Hematite Ore Based on Biomass Pyrolysis

Direct reduction of high-phosphorus oolitic hematite ore based on biomass pyrolysis gases (CO, H2, and CH4), tar, and char was conducted to investigate the effects of reduction temperature, iron ore-biomass mass ratio, and reduction time on the metallization rate. In addition, the effect of particle size on the dephosphorization and iron recovery rate was studied by magnetic separation. It was determined that the metallization rate of the hematite ore could reach 99. 35% at iron ore-biomass mass ratio of 1: 0. 6, reduction temperature of 1100 °C, and reduction time of 55 min. The metallization rate and the aggregation degree of iron particles increase with the increase of reduction temperature. The particle size of direct reduced iron (DRI) has a great influence on the quality of the iron concentrate during magnetic separation. The separation degree of slag and iron was improved by the addition of 15 mass% sodium carbonate. DRI with iron grade of 89. 11%, iron recovery rate of 83. 47%, and phosphorus content of 0. 28% can be obtained when ore fines with particle size of — 10 μm account for 78. 15%.

Synchronous Upgrading Iron and Phosphorus Removal from High Phosphorus Oolitic Hematite Ore by High Temperature Flash Reduction

In this paper, an effective method was developed to remove phosphorus and upgrade iron from high phosphorus oolitic hematite ore by high temperature flash reduction—a wet magnetic separation process. A thermodynamic analysis of iron and phosphorus mineral reactions and experiments with Fe-P separation process were performed, and the mechanism of phosphorus removal and beneficiation of iron is discussed as well. The results show that under the proper conditions, a final metallic iron powder assaying over 91% Fe and 0.25% P was obtained with iron recovery of 90% and phosphorus removal rate of 91.79% using the new process, indicating that the high temperature flash reduction process is a feasible and efficient way to process this kind of complex and refractory iron ore. Moreover, sodium sulfate is found to be capable of improving the removal of phosphorus and the upgrading of iron, as well as enhancing the growth of metallic iron grains significantly for higher recovery of iron.

Enrichment of phosphorus in reduced iron during coal based reduction of high phosphorus-containing oolitic hematite ore

With the objective of phosphorus enrichment in the metallic iron during coal based reduction, high phosphorus oolitic hematite ore was reduced in the presence of coal with the coal/ore molar ratio (C/O, the molar ratio of fixed carbon in coal to oxygen in iron oxides of ore) varying from 1·0 to 2·5 at temperatures ranging from 1473 to 1548 K. The metallic iron was beneficiated from reduction products by magnetic separation. The results showed that the enrichment of phosphorus in the metallic iron improved with increasing temperature and C/O molar ratio. The phosphorus content and the phosphorus enrichment could reach 2·5 and 77·5%, respectively, with a C/O molar ratio of 2·5 at 1548 K and after 60 min reduction. The high phosphorus-containing metallic iron so obtained could then be converted to steel and high phosphorus steelmaking slag that can be used as a phosphate fertiliser. Kinetic analysis demonstrated that the process of phosphorus enrichment in the metallic iron could be divided into two stages, early and late, described by phase boundary controlled reaction and diffusion controlled, respectively. At the early stage, the apparent activation energy and pre-exponential factor of phosphorus enrichment decreased from 182·12 kJ mol−1 and 9509·06 min−1 to 132·60 kJ mol−1 and 395·44 min−1, respectively, when the C/O molar ratio was increased from 1·0 to 2·5. At the later stage, the apparent activation energy and pre-exponential factor were 245·87 kJ mol−1 and 172 818·99 min−1 at a C/O molar ratio of 1·0, respectively, whilst those were reduced to 210·73 kJ mol−1 and 13 930·28 min−1 at a C/O molar ratio of 2·5.

Effect of Coal Type on the Reduction and Magnetic Separation of a High-phosphorus Oolitic Hematite Ore

Coal-based direct reduction followed by magnetic separation technique was employed to produce direct reduction iron powder (DRI powder) from a high-phosphorus oolitic hematite ore, and the effects of type and particle size of coal and C/O (Fixed carbon/Oxygen) mole ratio on this process were investigated. The results showed that when using coarse-sized and medium-sized coals, bitumite and lignite presented better iron recovery as compared with anthracite, while this advantage disappeared as the particle size of coals decreased. In addition, the iron content of the DRI powder increased with improving of the coal rank depended on fixed carbon contents, while decreased with the decrease of particle size of coals. Increasing the C/O ratio resulted in a sharp rise of P content of the DRI powder. X-Ray Diffraction (XRD) analysis revealed that more liquid phase was formed in the briquettes during reduction with anthracite as reductant. SEM (scanning electron microscope) observation confirmed that the size of the metallic iron grains formed in reduced briquettes decreased with decreasing of the rank of the coal and the particle size of coal.

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.

Preparation of Iron Carbide from High Phosphorus Oolitic Hematite

In order to find a new way to utilize the high phosphorus oolitic hematite ore as raw material for steelmaking, the reduction and carburization of high phosphorus oolitic hematite by the gas of CH4-H2were studied. High phosphorus oolitic hematite, reduction and carburization products were investigated by the means of XRD and scanning electron microscope. The SEM-EDS and XRD analysis show that the main compositions of this ore are hematite and quartz, main microstructure is oolitic cluster with the zonal distribution of hematite and apatite, and iron carbide can be prepared from high phosphorus oolitic hematite.

Effects of Fuel on Gasification Dephosphorization of High-Phosphorus Oolitic Hematite Ore

Through using jiuquan bituminous coal, yangquan anthracite, coking coal and charcoal as fuel,under 900 °C simulating the preheat layer of sinter process,research the influence of fuel types and content on gasification dephosphorization.Results show that due to the different volatile matter of coal, the influence on gasification dephosphorization is different, the influence of the highest volatile bituminous coal to the dephosphorization effect is best when carbon content takes 4%.

Effects of sodium salts on reduction roasting and Fe–P separation of high-phosphorus oolitic hematite ore

Effects of sodium salts on reduction roasting and Fe–P separation of high-phosphorus oolitic hematite ore were studied in the process of coal-based direct reduction followed by wet magnetic separation. Various parameters, including reducing temperature and time, type and dosage of sodium salts, grinding fineness of magnetic separation feed and magnetic field intensity were investigated. The results of reduction and Fe–P magnetic separation are significantly improved by the addition of sodium sulfate and borax, in comparison with those in the absence of additives. A magnetic concentrate with total iron grade of 92.7% and phosphorus content of 0.09% was obtained from an oolitic hematite ore containing 48.96% iron and 1.61% phosphorus when reduced in the presence of 7.5% sodium sulfate and 1.5% borax and wet magnetic separated under the proper conditions. The results of optical microscopy and X-ray diffraction (XRD) analyses of reduced pellet reveal that metallic iron grains exist in sizes of 10–20μm and are associated with gangue minerals closely when reduced in the absence of sodium salts. By contrast, the oolitic structure is destroyed and metallic iron grains grow markedly to the mean size of 50μm when reduced in the presence of sodium sulfate and borax. Sodium salts are capable of destroying the oolitic structure via reacting with gangues, enhancing the reduction of iron oxide and promoting the growth of metallic iron grains during reduction, which is beneficial for Fe–P separation of the oolitic hematite ore.

Effect of coal levels during direct reduction roasting of high phosphorus oolitic hematite ore in a tunnel kiln

The effect of coal levels on phosphorus removal from a high phosphorus oolitic hematite ore after direct reduction roasting have been investigated. Raw ore, coal, and a dephosphorization agent were mixed and the mixture was then roasted in a tunnel kiln. The roasted products were treated by two stages of grinding followed by magnetic separation. XRD and SEM–EDS examination of the products was used to analyze differences in the roasted products. The results show that coal is one of the most important factors affecting the direct reduction roasting process. When the inner coal levels increased from 0% to 15% the iron grade decreased linearly from 94.94% to 88.81% and the iron recovery increased from 55.94% to 92.94%. At the same time the phosphorus content increased from 0.045% to 0.231%. Increasing the inner coal levels also caused more hematite to be reduced to metallic iron but the oolitic structure of the roasted product was preserved in the presence of high coal loading. The phase of the phosphorus in raw ore was not changed after direct reduction roasting. The effect of coal on the phosphorus content in the H-concentrate arises from changes in the difficulty of mechanically liberating the metallic iron from the phosphorus bearing minerals.

Industry Test on Phosphorus Removal and Direct Reduction of High-Phosphorus Oolitic Hematite Ore

Industry test on phosphorus removal and direct reduction of the “Ningxiang type” high-phosphorus oolitic hematite ore has been carried out in a tunnel kiln on the basis of laboratory experiment. The iron grade and phosphorus content of the initial sample are 42.46% and 0.867%, respectively. The results showed that high-phosphorus oolitic hematite could be exploited on industrial scale, with the new process direct reduction roasting – grinding – magnetic separation, and that the final concentrate with an iron grade 92.56%, iron recovery 82.77% and phosphorus content 0.089% was obtained under the optimal conditions. Besides, X-ray diffraction (XRD) and scanning electron microscope with X-ray energy dispersive spectrum (SEM-EDS) were used to analysis the mechanism of phosphorus removal and direct reduction. It was shown that oolitic structure was destroyed, and metallic iron particle coarsening was obvious, besides fluorapatite particles were dispersed in the gangue by diffusion during the reduction roasting process. The liberation of metallic iron and gangue can be achieved by grinding, so high iron grade and low phosphorus content concentrate can be obtained after magnetic separation.