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Suzanne A Mcenroe - One of the best experts on this subject based on the ideXlab platform.
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magnetization of exsolution intergrowths of hematite and Ilmenite mineral chemistry phase relations and magnetic properties of hemo Ilmenite ores with micron to nanometer scale lamellae from allard lake quebec
2007Co-Authors: Suzanne A Mcenroe, Peter Robinson, Falko Langenhorst, Cathrine Frandsen, Michael P Terry, Tiziana Boffa BallaranAbstract:Hemo-Ilmenite ores from Allard Lake, Quebec, were first studied over 50 years ago. Interest was renewed in these coarsely exsolved oxides, based on the theory of lamellar magnetism as an explanation for the high and stable natural remanent magnetizations (NRMs), 32 to 120 A/m, reported here. To understand the magnetism and evolution of the exsolution lamellae, the microstructures and nanostructures were studied using scanning electron microscopy and transmission electron microscopy (TEM), phase chemistry, and relations between mineral chemistry and the hematite-Ilmenite phase diagram. Cycles of exsolution during slow cooling resulted in lamellae down to 1-2 nm thick. Combined electron microprobe, TEM, and X-ray diffraction (XRD) results indicate that hematite hosts reached a composition approximately Ilmenite (Ilm) 14.4, and Ilmenite hosts ∼Ilm 98. The bulk of the very stable NRM, which shows thermal unblocking ∼595-620°C, was acquired during final exsolution in the two-phase region canted antiferromagnetic R3c hematite + R3 Ilmenite. Hysteresis measurements show a very strong anisotropy, with a stronger coercivity normal to, than parallel to, the basal plane orientation of the lamellae. Magnetic saturation (M s ) values are up to 914 A/m, compared to 564 A/m predicted for a modally equivalent spin-canted hematite corrected for ∼15% R 2+ TiO 3 substitution. Low-temperature hysteresis, AC-susceptibility measurements, and Mossbauer results indicate a Neel temperature (T N ) of the geikielite-substituted Ilmenite at ∼43 K. The low-temperature hysteresis and AC-susceptibility measurements also show a cluster-spin-glass-like transition near 20 K. Below T N of Ilmenite an exchange bias occurs with a 40 mT shift at 10 K.
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effects of nanoscale exsolution in hematite Ilmenite on the acquisition of stable natural remanent magnetization
2004Co-Authors: Takeshi Kasama, Suzanne A Mcenroe, Noriaki Ozaki, Toshihiro Kogure, Andrew PutnisAbstract:Abstract To investigate the acquisition mechanism of high and stable natural remanent magnetization (NRM) in rocks of the Russell Belt, Adirondack Mountains, New York, we examined the exsolution microstructures and compositions of magnetic minerals using three samples with different magnetic properties. The samples contain titanohematite with Ilmenite lamellae, end-member hematite without lamellae and rare magnetite as potential carriers for the NRM. Transmission electron microscopy (TEM) observations and element mapping by energy-filtered TEM (EFTEM) of the titanohematite indicated that very fine Ilmenite lamellae with a minimum thickness ∼2 nm are abundant between larger Ilmenite lamellae a few hundreds of nanometers thick. The Ilmenite lamellae and titanohematite hosts, with the compositions of Ilm 90–100 Hem 10–0 and Ilm 7–16 Hem 93–84 , respectively, share (001) planes, and the abundant fine Ilmenite lamellae have coherent, sharp structural and compositional interfaces with their titanohematite hosts. Comparison between samples shows that the magnetization is correlated with the amount of fine exsolution lamellae. These results are consistent with the lamellar magnetism hypothesis, suggesting that the acquisition of high and stable NRM is related to the interfacial area between fine Ilmenite lamellae and their host titanohematite. End-member hematite with a multi-domain magnetic structure only contributes a minor amount to the NRM in these samples.
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nanoscale haematite Ilmenite lamellae in massive Ilmenite rock an example of lamellar magnetism with implications for planetary magnetic anomalies
2002Co-Authors: Suzanne A Mcenroe, Peter Robinson, Richard J Harrison, Falko LangenhorstAbstract:Summary Massive, nearly ‘pure’, haemo-Ilmenite layers from historic ore deposits in Rogaland, Norway contain very few silicates or other oxides and typically produce remanence-dominated magnetic anomalies. These rocks are ideal for evaluating the magnetic properties of fine exsolution intergrowths and the larger titanohaematite lamellae in the host Ilmenite grains. A typical bulk composition, Ilm 84, exsolved at high temperature to produce host Ilmenite Ilm 94 and micron-sized haematite lamellae Ilm 23 as measured by electron microprobe (EMP). Subsequent undercooling of the Ilmenite and the micron-scale haematite lamellae led to metastable nucleation of nanoscale lamellae down to unit-cell scale, leaving depleted hosts between lamellae with compositions of Ilm 98 and Ilm 15–13 as measured by TEM–EDX. Samples have high coercivities, and average NRM values of 25 A m−1, which typically show ∼2 per cent saturation in the NRM state. The amount of magnetization in these samples is too high to be solely accounted for by a spin-canted AF moment in the haematite. Based on Monte Carlo simulations of haematite–Ilmenite interfaces at the atomic scale and on measured rock-magnetic properties, we predict that the magnetization is carried by a ferrimagnetic substructure produced at the contacts of the very fine-scale titanohaematite and Ilmenite exsolution lamellae.
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effect of fine scale microstructures in titanohematite on the acquisition and stability of natural remanent magnetization in granulite facies metamorphic rocks southwest sweden implications for crustal magnetism
2001Co-Authors: Suzanne A Mcenroe, Peter Robinson, Richard J Harrison, Ute Golla, Michael J JercinovicAbstract:Mid-Proterozoic granulites in SW Sweden, having opaque minerals hematiteIlmenite with minor magnetite, and occurring in an area with negative aeromagnetic anomalies, have strong and stable reversed natural remanent magnetization ∼9.2 A/m, with 100% remaining after demagnetization to 100 mT. Samples were characterized by optical microscopy, electron microprobe (EMP), transmission electron microscopy (TEM), and rock-magnetic measurements. Earliest oxide equilibrium was between grains of titanohematite and ferri-Ilmenite at 650°–600°C. Initial contacts were modified by many exsolution cycles. Hematite and Ilmenite (Ilm) hosts and lamellae by EMP are Ilm 24–25, ILm 88–93, like titanohematite, and Ilmenite above 520°C on Burton's diagram [1991]. Finer hosts and lamellae by TEM are Ilm16 ±3 and Ilm 88±4, like coexisting antiferromagnetically ordered (AF) hematite and Ilmenite below 520°C on Burton's diagram. This may be the first example of analytical identification, in one sample, of former hematite, now finely exsolved, and AF hematite. TEM microstructures consist of gently curving semicoherent Ilmenite lamellae within hematite, flanked by precipitate-free zones and abundant Ilmenite disks down to unit cell scale (1–2 nm). Strain contrast of disks suggests full coherence with the host, and probable formation at the reaction titanohematite ---> AF hematite + Ilmenite at 520°C. Magnetic properties are a consequence of chemical and magnetic evolution of hematite and Ilmenite with bulk compositions Ilmenite-richer than Ilm 28, that apparently exsolved without becoming magnetized, down to 520°C where hematite broke down to AF hematite plus Ilmenite, producing abundant AF hematite below its Neel temperature. Intensity of magnetization is greater than possible with hematite alone, and TEM work suggests that ultrafine Ilmenite disks in AF hematite are associated with a ferrimagnetic moment due to local imbalance of up and down spins at coherent interfaces.
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minor element chemistry of hemo Ilmenite and magnetite in cumulate rocks from the sokndal region south rogaland norway
2001Co-Authors: Peter Robinson, Peter T Panish, Suzanne A McenroeAbstract:Chemistry of the Fe-Ti oxide minerals in the Bjerkreim-Sokndal layered intrusion and in the Tellnes Ilmenite Norite suggests some parallels in magmatic evolution and resultant petrography. Early Ilmenites have high ratios of Mg/(Mg + Fe) and Cr/R 3+ and intermediate to low V/R 3+ , and abundant fine hematite exsolution lamellae, in which Cr, V, and Al are concentrated. Magmatic evolution results in lower Mg/(Mg + Fe), lower Cr/R 3+ and higher V/R 3+ . With magma saturation with magnetite, V/R 3+ falls both in Ilmenite of rapidly decreasing abundance, and in magnetite, but there is an increase in Mg/(Mg + Fe) of Ilmenite, probably due to late ion exchange with much more abundant magnetite. Aside from implications related to magma evolution, these results give information concerning fractionation of elements between the rhombohedral and cubic oxide series, and especially between the Ilmenite hosts and their contained hematite exsolution lamellae.
Peter Robinson - One of the best experts on this subject based on the ideXlab platform.
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magnetization of exsolution intergrowths of hematite and Ilmenite mineral chemistry phase relations and magnetic properties of hemo Ilmenite ores with micron to nanometer scale lamellae from allard lake quebec
2007Co-Authors: Suzanne A Mcenroe, Peter Robinson, Falko Langenhorst, Cathrine Frandsen, Michael P Terry, Tiziana Boffa BallaranAbstract:Hemo-Ilmenite ores from Allard Lake, Quebec, were first studied over 50 years ago. Interest was renewed in these coarsely exsolved oxides, based on the theory of lamellar magnetism as an explanation for the high and stable natural remanent magnetizations (NRMs), 32 to 120 A/m, reported here. To understand the magnetism and evolution of the exsolution lamellae, the microstructures and nanostructures were studied using scanning electron microscopy and transmission electron microscopy (TEM), phase chemistry, and relations between mineral chemistry and the hematite-Ilmenite phase diagram. Cycles of exsolution during slow cooling resulted in lamellae down to 1-2 nm thick. Combined electron microprobe, TEM, and X-ray diffraction (XRD) results indicate that hematite hosts reached a composition approximately Ilmenite (Ilm) 14.4, and Ilmenite hosts ∼Ilm 98. The bulk of the very stable NRM, which shows thermal unblocking ∼595-620°C, was acquired during final exsolution in the two-phase region canted antiferromagnetic R3c hematite + R3 Ilmenite. Hysteresis measurements show a very strong anisotropy, with a stronger coercivity normal to, than parallel to, the basal plane orientation of the lamellae. Magnetic saturation (M s ) values are up to 914 A/m, compared to 564 A/m predicted for a modally equivalent spin-canted hematite corrected for ∼15% R 2+ TiO 3 substitution. Low-temperature hysteresis, AC-susceptibility measurements, and Mossbauer results indicate a Neel temperature (T N ) of the geikielite-substituted Ilmenite at ∼43 K. The low-temperature hysteresis and AC-susceptibility measurements also show a cluster-spin-glass-like transition near 20 K. Below T N of Ilmenite an exchange bias occurs with a 40 mT shift at 10 K.
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nanoscale haematite Ilmenite lamellae in massive Ilmenite rock an example of lamellar magnetism with implications for planetary magnetic anomalies
2002Co-Authors: Suzanne A Mcenroe, Peter Robinson, Richard J Harrison, Falko LangenhorstAbstract:Summary Massive, nearly ‘pure’, haemo-Ilmenite layers from historic ore deposits in Rogaland, Norway contain very few silicates or other oxides and typically produce remanence-dominated magnetic anomalies. These rocks are ideal for evaluating the magnetic properties of fine exsolution intergrowths and the larger titanohaematite lamellae in the host Ilmenite grains. A typical bulk composition, Ilm 84, exsolved at high temperature to produce host Ilmenite Ilm 94 and micron-sized haematite lamellae Ilm 23 as measured by electron microprobe (EMP). Subsequent undercooling of the Ilmenite and the micron-scale haematite lamellae led to metastable nucleation of nanoscale lamellae down to unit-cell scale, leaving depleted hosts between lamellae with compositions of Ilm 98 and Ilm 15–13 as measured by TEM–EDX. Samples have high coercivities, and average NRM values of 25 A m−1, which typically show ∼2 per cent saturation in the NRM state. The amount of magnetization in these samples is too high to be solely accounted for by a spin-canted AF moment in the haematite. Based on Monte Carlo simulations of haematite–Ilmenite interfaces at the atomic scale and on measured rock-magnetic properties, we predict that the magnetization is carried by a ferrimagnetic substructure produced at the contacts of the very fine-scale titanohaematite and Ilmenite exsolution lamellae.
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effect of fine scale microstructures in titanohematite on the acquisition and stability of natural remanent magnetization in granulite facies metamorphic rocks southwest sweden implications for crustal magnetism
2001Co-Authors: Suzanne A Mcenroe, Peter Robinson, Richard J Harrison, Ute Golla, Michael J JercinovicAbstract:Mid-Proterozoic granulites in SW Sweden, having opaque minerals hematiteIlmenite with minor magnetite, and occurring in an area with negative aeromagnetic anomalies, have strong and stable reversed natural remanent magnetization ∼9.2 A/m, with 100% remaining after demagnetization to 100 mT. Samples were characterized by optical microscopy, electron microprobe (EMP), transmission electron microscopy (TEM), and rock-magnetic measurements. Earliest oxide equilibrium was between grains of titanohematite and ferri-Ilmenite at 650°–600°C. Initial contacts were modified by many exsolution cycles. Hematite and Ilmenite (Ilm) hosts and lamellae by EMP are Ilm 24–25, ILm 88–93, like titanohematite, and Ilmenite above 520°C on Burton's diagram [1991]. Finer hosts and lamellae by TEM are Ilm16 ±3 and Ilm 88±4, like coexisting antiferromagnetically ordered (AF) hematite and Ilmenite below 520°C on Burton's diagram. This may be the first example of analytical identification, in one sample, of former hematite, now finely exsolved, and AF hematite. TEM microstructures consist of gently curving semicoherent Ilmenite lamellae within hematite, flanked by precipitate-free zones and abundant Ilmenite disks down to unit cell scale (1–2 nm). Strain contrast of disks suggests full coherence with the host, and probable formation at the reaction titanohematite ---> AF hematite + Ilmenite at 520°C. Magnetic properties are a consequence of chemical and magnetic evolution of hematite and Ilmenite with bulk compositions Ilmenite-richer than Ilm 28, that apparently exsolved without becoming magnetized, down to 520°C where hematite broke down to AF hematite plus Ilmenite, producing abundant AF hematite below its Neel temperature. Intensity of magnetization is greater than possible with hematite alone, and TEM work suggests that ultrafine Ilmenite disks in AF hematite are associated with a ferrimagnetic moment due to local imbalance of up and down spins at coherent interfaces.
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minor element chemistry of hemo Ilmenite and magnetite in cumulate rocks from the sokndal region south rogaland norway
2001Co-Authors: Peter Robinson, Peter T Panish, Suzanne A McenroeAbstract:Chemistry of the Fe-Ti oxide minerals in the Bjerkreim-Sokndal layered intrusion and in the Tellnes Ilmenite Norite suggests some parallels in magmatic evolution and resultant petrography. Early Ilmenites have high ratios of Mg/(Mg + Fe) and Cr/R 3+ and intermediate to low V/R 3+ , and abundant fine hematite exsolution lamellae, in which Cr, V, and Al are concentrated. Magmatic evolution results in lower Mg/(Mg + Fe), lower Cr/R 3+ and higher V/R 3+ . With magma saturation with magnetite, V/R 3+ falls both in Ilmenite of rapidly decreasing abundance, and in magnetite, but there is an increase in Mg/(Mg + Fe) of Ilmenite, probably due to late ion exchange with much more abundant magnetite. Aside from implications related to magma evolution, these results give information concerning fractionation of elements between the rhombohedral and cubic oxide series, and especially between the Ilmenite hosts and their contained hematite exsolution lamellae.
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aeromagnetic anomalies magnetic petrology and rock magnetism of hemo Ilmenite and magnetite rich cumulate rocks from the sokndal region south rogaland norway
2001Co-Authors: Suzanne A Mcenroe, Peter Robinson, Peter T PanishAbstract:Aeromagnetic maps of the Egersund Mid-Proterozoic igneous province show a spectacular range of positive and negative magnetic anomalies with a contrast up to 15 600 nT. The positive magnetic anomalies are over magnetite norites and overlying mangerites and quartz mangerites of the Bjerkreim-Sokndal layered intrusion. These rocks are dominated by multi-domain (MD) magnetite. The negative magnetic anomalies are over Ilmenite-rich norites of the Bjerkreim-Sokndal layered intrusion, the Tellnes Ilmenite norite ore deposit, and massif anorthosites. These rocks are dominated by hemo-Ilmenite and/or by silicates containing fine-grained oxide exsolution lamellae. Electron microprobe analyzes of coexisting Fe-Ti oxides in the layered intrusion confirm earlier observations that oxides in early magmatic rocks are dominated by hemo-Ilmenite with minor end-member magnetite, followed by more reduced oxides dominated by titanomagnetite with minor near end-member Ilmenite. What is not fully understood is the property of Ilmenite with hematite exsolution lamellae, or, even more striking, hematite with Ilmenite lamellae, to produce strong remanent magnetization of high coercivity and with a Neel temperature equal to or above the Curie temperature of magnetite. This property makes the rhombohedral oxides an important candidate to explain some high-amplitude deep-crustal anomalies on earth, or strong remanent magnetization on other planets. A remarkable feature in the Egersund province is that primitive magmas produced rocks rich in hemo-Ilmenite causing negative magnetic anomalies related to magnetic remanence, and more evolved magmas produced rocks rich in magnetite related to positive induced magnetic anomalies, all in the course of crystallization-differentiation.
Peter T Panish - One of the best experts on this subject based on the ideXlab platform.
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minor element chemistry of hemo Ilmenite and magnetite in cumulate rocks from the sokndal region south rogaland norway
2001Co-Authors: Peter Robinson, Peter T Panish, Suzanne A McenroeAbstract:Chemistry of the Fe-Ti oxide minerals in the Bjerkreim-Sokndal layered intrusion and in the Tellnes Ilmenite Norite suggests some parallels in magmatic evolution and resultant petrography. Early Ilmenites have high ratios of Mg/(Mg + Fe) and Cr/R 3+ and intermediate to low V/R 3+ , and abundant fine hematite exsolution lamellae, in which Cr, V, and Al are concentrated. Magmatic evolution results in lower Mg/(Mg + Fe), lower Cr/R 3+ and higher V/R 3+ . With magma saturation with magnetite, V/R 3+ falls both in Ilmenite of rapidly decreasing abundance, and in magnetite, but there is an increase in Mg/(Mg + Fe) of Ilmenite, probably due to late ion exchange with much more abundant magnetite. Aside from implications related to magma evolution, these results give information concerning fractionation of elements between the rhombohedral and cubic oxide series, and especially between the Ilmenite hosts and their contained hematite exsolution lamellae.
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aeromagnetic anomalies magnetic petrology and rock magnetism of hemo Ilmenite and magnetite rich cumulate rocks from the sokndal region south rogaland norway
2001Co-Authors: Suzanne A Mcenroe, Peter Robinson, Peter T PanishAbstract:Aeromagnetic maps of the Egersund Mid-Proterozoic igneous province show a spectacular range of positive and negative magnetic anomalies with a contrast up to 15 600 nT. The positive magnetic anomalies are over magnetite norites and overlying mangerites and quartz mangerites of the Bjerkreim-Sokndal layered intrusion. These rocks are dominated by multi-domain (MD) magnetite. The negative magnetic anomalies are over Ilmenite-rich norites of the Bjerkreim-Sokndal layered intrusion, the Tellnes Ilmenite norite ore deposit, and massif anorthosites. These rocks are dominated by hemo-Ilmenite and/or by silicates containing fine-grained oxide exsolution lamellae. Electron microprobe analyzes of coexisting Fe-Ti oxides in the layered intrusion confirm earlier observations that oxides in early magmatic rocks are dominated by hemo-Ilmenite with minor end-member magnetite, followed by more reduced oxides dominated by titanomagnetite with minor near end-member Ilmenite. What is not fully understood is the property of Ilmenite with hematite exsolution lamellae, or, even more striking, hematite with Ilmenite lamellae, to produce strong remanent magnetization of high coercivity and with a Neel temperature equal to or above the Curie temperature of magnetite. This property makes the rhombohedral oxides an important candidate to explain some high-amplitude deep-crustal anomalies on earth, or strong remanent magnetization on other planets. A remarkable feature in the Egersund province is that primitive magmas produced rocks rich in hemo-Ilmenite causing negative magnetic anomalies related to magnetic remanence, and more evolved magmas produced rocks rich in magnetite related to positive induced magnetic anomalies, all in the course of crystallization-differentiation.
Jun Tan - One of the best experts on this subject based on the ideXlab platform.
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hydrochloric acid leaching behavior of different treated panxi Ilmenite concentrations
2011Co-Authors: Li Zhang, Qiyuan Chen, Zhi Liao, Jun TanAbstract:Abstract The effects of oxidation–reduction treatment and mechanical activation on the hydrochloric acid leaching performance of Panxi Ilmenite concentration from Sichuan province of China were investigated. The results show that both of oxidation–reduction treatment and mechanical activation not only significantly accelerated the extraction of Fe, Ca and Mg from Panxi Ilmenite concentration, but also apparently put forward the initial hydrolysis time of titanium ions in hydrochloric acid solution. In addition, oxidation–reduction treatment can obviously decrease the Ti extraction in hydrochloric acid solution. The formation of pseudobrookite by oxidizing at 900 °C is more favorable to upgrade Panxi Ilmenite concentration to synthetic rutile. A process of “oxidation–reduction–mechanical activation–hydrochloric acid leaching” was proposed, and this process successfully prepared the synthetic rutile which meets the requirements of chlorination process. In this process, the Panxi Ilmenite concentration is first oxidized at 900 °C in the presence of oxygen for 15 min, then reduced at 750 °C by hydrogen for 30 min. After cooled to room temperature in a nitrogen atmosphere, the oxidized–reduced Ilmenite concentration obtained is milled in a planetary ball mill for 2 h under nitrogen atmosphere immediately. After the milling, the oxidized–reduced–mechanically activated Ilmenite concentration proceeds to a leaching at ambient pressure using 20 wt.% hydrochloric acid for 10 h. Finally, the leached product is subjected to filtration, wash and calcination to produce a synthetic rutile containing 90.50 wt.% TiO 2 and 1.37 wt.% total iron as well as combined CaO and MgO of 1.00 wt.%. The results demonstrate that the process of “oxidation–reduction–mechanical activation–hydrochloric acid leaching” can excellently upgrade Ilmenite concentration with high content of gangue like Panxi Ilmenite concentration into synthetic rutile which meets the requirements of chlorination process.
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hydrochloric acid leaching behaviour of mechanically activated panxi Ilmenite fetio3
2010Co-Authors: Li Zhang, Liangping Wei, Qiyuan Chen, Jun TanAbstract:The effects of mechanical activation on the hydrochloric acid leaching performance of Panxi Ilmenite from Sichuan province of China were investigated. The unactivated and mechanically activated Ilmenites were characterized using X-ray diffraction (XRD), particle size analysis, and Scanning Electron Microscope (SEM) techniques to determine the structural changes of Panxi Ilmenite during the mechanical activation process. The results show that mechanical activation elevated the calcium, magnesium and iron extraction of Panxi Ilmenite irreversibly which mostly attributes to the lattice disorder of Panxi Ilmenite. All the results show that a great amount of magnesium in Panxi Ilmenite uniformly substitutes for iron in the structure of Ilmenite, while a minority magnesium exists in gangue minerals, and calcium more likely exists in gangue minerals. The sites of magnesium, calcium and iron in Ilmenite would not be redistributed during the treatment of mechanical activation.
Hongzhong Li - One of the best experts on this subject based on the ideXlab platform.
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influence of redox pretreatment on the pulverization of panzhihua Ilmenite during hydrochloric acid leaching
2015Co-Authors: Jianbo Zhang, Hongzhong LiAbstract:The influence of oxidation-reduction (redox) pretreatment on the pulverization of Panzhihua Ilmenite during hydrochloric acid leaching to obtain synthetic rutile was investigated in detail. We observed the dissociation of incompact TiO2 products formed via the dissolution-hydrolysis of Ti ions, which was caused by the fast dissolution of FeTiO3 during the leaching process and was the fundamental reason for pulverization for the raw Panzhihua Ilmenite. A stirring operation during the acid leaching aggravated the pulverization phenomenon. The formation and consumption of insoluble rutile grains during the redox pretreatment played a key role in preventing the pulverization of pre-treated Ilmenites. The rutile network formed during the pre-oxidation was retained and served as a nucleus for the hydrolyzed product during the successive leaching process, providing the leaching products of the pre-oxidized Ilmenite with less hydrolyzed TiO2, higher mechanical strength, and thus an excellent resistance to pulverization, even with stirred leaching. Because the following weak reduction process (reduction of ferric iron to ferrous state) at relatively low temperatures (e.g., 873 K) did not destroy the rutile network that was formed by the pre-oxidation, it did not change the ability of the pre-oxidation to prevent the pulverization of Ilmenite. However, the weak reduction process at high temperatures (e.g. 1023 K) weakened the effect of pre-oxidation because most of the futile grains that were formed by the pre-oxidation were consumed and formed FeTiO3. (C) 2015 Elsevier B.V. All rights reserved.
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influence of redox pretreatment on the pulverization of panzhihua Ilmenite during hydrochloric acid leaching
2015Co-Authors: Jianbo Zhang, Hongzhong LiAbstract:The influence of oxidation-reduction (redox) pretreatment on the pulverization of Panzhihua Ilmenite during hydrochloric acid leaching to obtain synthetic rutile was investigated in detail. We observed the dissociation of incompact TiO2 products formed via the dissolution-hydrolysis of Ti ions, which was caused by the fast dissolution of FeTiO3 during the leaching process and was the fundamental reason for pulverization for the raw Panzhihua Ilmenite. A stirring operation during the acid leaching aggravated the pulverization phenomenon. The formation and consumption of insoluble rutile grains during the redox pretreatment played a key role in preventing the pulverization of pre-treated Ilmenites. The rutile network formed during the pre-oxidation was retained and served as a nucleus for the hydrolyzed product during the successive leaching process, providing the leaching products of the pre-oxidized Ilmenite with less hydrolyzed TiO2, higher mechanical strength, and thus an excellent resistance to pulverization, even with stirred leaching. Because the following weak reduction process (reduction of ferric iron to ferrous state) at relatively low temperatures (e.g., 873 K) did not destroy the rutile network that was formed by the pre-oxidation, it did not change the ability of the pre-oxidation to prevent the pulverization of Ilmenite. However, the weak reduction process at high temperatures (e.g. 1023 K) weakened the effect of pre-oxidation because most of the futile grains that were formed by the pre-oxidation were consumed and formed FeTiO3. (C) 2015 Elsevier B.V. All rights reserved.
