Iron Oxide Ore Research Articles

Перетворення гематиту та гетиту на магнетит у водному середовищі за дії мікрохвильового випромінювання

There are three main types of industrial iron ores in Kryvyi Rih basin: rich ore that are directly used in metallurgy, magnetite ore and oxidized ferruginous quartzites that need enrichment. Deposits of rich ore are depleted. Nowadays, ferruginous quartzites are the main part of all deposits of Kryvyi Rih basin. Main commercial significance of ferruginous quartzites belongs to unoxidized magnetite and magnetite-hematite types but their reserves are nearly exhausted. But, there are large reserves of oxidized iron ore available in Kryvyi Rih basin that could be used as raw material for concentrates’ production. It is known that production of iron ore concentrates from poor oxidized iron ores related with various problems. Processes of transformation were studied for three types of iron ores: hematite ore, oxidized hematite ore (two samples) and hematite-goethite ore from deposits of Kryvyi Rih. Transformation of hematite and goethite, which are main mineral components of iron ore, to magnetite by heating to temperature of 98°С in aqueous Fe+2-containing medium under microwave radiation was investigated. Phase composition of initial samples was determined by X-ray diffraction (XRD). It was shown by XRD method that hematite ore consists of quartz and hematite, oxidized hematite ores consist of hematite and kaolinite and hematite-goethite ore consists of hematite, goethite and quartz. It was shown by XRD method that, after transformation in all obtained samples appears a phase of magnetite. Saturation magnetization of initial and obtained samples was investigated by magnetometry method. Saturation magnetization of initial samples was < 1 А∙m2/кg. Saturation magnetization of obtained samples was within the range 8-30 A·m2/kg. Possible mechanisms of hematite and goethite transformation to magnetite have been described. The results could be used for the development of effective techniques of iron ores enrichment for ore concentrates creation.

The possible synglaciogenic Ediacaran hematitic banded iron salt formation (BISF) at Hormuz Island, southern Iran: Implications for a new style of exhalative hydrothermal iron-salt system

The Ediacaran BISF at Hormuz Island is a newly identified glaciogenic iron-salt deposit in the Tethyan margin of Gondwana. The BISF was formed by synchronous riftogenic A-type submarine felsic volcanism and evaporate deposition. The mineralization occurs in a proximal felsic tuff cone and jaspilitic distal zones and contains 1 million tonne of hematite-rich ore with an average grade of 58% Fe. The ore structure shows cyclicity of macrobandings, mesobandings and microbandings of anhydrite, halite, hematite and chert, which marks a new record in BIFs geohistory. The alteration minerals in the proximal and distal zones are actinolite, ripidolite, epidote, sericite, tourmaline, clinochlore, anhydrite and clay minerals. The occurrence of metamorphosed polygenetic bullet-shape dropstones in BISF attests that there was probably a continuous process of ice melting, episodic submarine volcanism and exhalative hydrothermal banded iron salt formation during the Late Ediacaran time. The non-metamorphosed Neoproterozoic stratigraphy, the presence of genus Collenia, U-Pb dating (558±7Ma) and the marked negative δ13C excursion in cap carbonates are representative of Late Ediacaran glaciation, which has been identified worldwide. The REE+Y display light REE enrichment, unusually strong Tb-Tm anomaly, a weak positive Y anomaly, but no distinguished Eu and Ce anomalies, reflecting the glaciogenic nature of the BISF. The contents of Zr, Hf, Nb, Ta, Th, La, Ce and Y in BISF, dropstones, halite and cap carbonates are similar to those of the Neoproterozoic glaciogenic BIFs. Also, the Ni/Fe, P/Fe ratios and Fe/Ti – Al/Al+Fe+Mn+Ca+Na+K diagram suggest an exhalative hydrothermal Ediacaran-type BISF. The absence of brecciated magnetite in the ore association and the low contents of copper (9–493ppm) and gold (<5–8ppb) are not in favor of the IOCG – Kiruna-type iron oxide ores. The co-paragenesis of hematite with several alteration minerals, in particular actinolite, tourmaline and anhydrite, indicates that the exhalative hydrothermal fluids were generated by the interaction of seawater with the felsic rocks and sediments at about 200–500°C. The interaction of seawater with felsic magma and sediments led to the formation of Mg-rich alteration minerals, leaching Si, Fe, Mn and other elements and forming the potential ore fluids. It is highlighted that the A-type alkaline submarine felsic volcanism could be considered as an exploration target for BISF.

Direct reduction of oxidized iron ore pellets using biomass syngas as the reducer

The syngas derived from a pyrolysis and gasification process was used as a reducing agent to produce iron ore pellets. The reduction temperature was kept between 1123K and 1323K, and the time was set 30min. Results showed that the reducibility increased from 88.1% at 1123K to 99.95% at 1323K. The reduction rate increased with increasing reduction temperature. Further, the reaction rate in the early stage was higher than that in the later stage.The X-ray diffraction (XRD) and metallographic microscope analyses of the oxidized pellets and direct reduced iron (DRI) products showed that, the reduction process followed the reaction scheme: Fe2O3→FeO→Fe. A kinetics analysis indicated that, the reduction rate was controlled by an interfacial chemical reaction with syngas and that the activation energy was 104.76kJ/mol. The effect of syngas as the reducing gas on the reduction of iron ore pellets was similar to that of natural gas. The use of biomass during DRI production can eliminate CO2 emissions, energy crisis, and climate change.

Металлургические шлаки из поселения Кент (к проблеме начала получения железа на территории Казахстана)

In the paper the characteristic of the iron metallurgical slags from Kent settlement (Central Kazakhstan) is shown. Structural and textural features of slags were established. The mineral composition is represented by olivine, wustite, iron, and glass. The composition of the main types of minerals, metal and glass is shown. It was supposed that as the metallurgical raw material in ancient times were used limonite ores from Kentyube deposit where ancient mines in oxidized iron ores were found out. On the settlement there was the early experience of iron production by metallurgists of Begazy-Dandybay (Alekseevsko-Sargarinskaya) culture of the eastern zone of the roll ceramic common culture on the territory of Kazakhstan. The Alat area with iron slags can be considered as the trade quarter of Kent town where metallurgists who produced bronze foundry items of original and traditional types of Eurasian metallurgical province, attempted to produce the iron.

New method of electrostatic separation of the oxidized iron ore

New method of electrostatic separation of the oxidized iron ore

The geology and genesis of the iron skarns of the Turgai belt, northwestern Kazakhstan

The magnetite deposits of the Turgai belt (Kachar, Sarbai and Sokolov), in the Valerianovskoe zone of the southern Urals, Kazakhstan, contain a combined resource of over 3Gt of iron oxide ore. The deposits are hosted by carbonate sediments and volcaniclastic rocks of the Carboniferous Valerianovka Supergroup, and are spatially related to the gabbroic to granitoid composition intrusive rocks of the Sarbai–Sokolov intrusive series. The magnetite deposits are developed dominantly as metasomatic replacement of limestone, but also, to a lesser extent, of volcanic rocks. Pre-mineralisation metamorphism and alteration resulted in the formation of wollastonite and the silicification of limestone. Magnetite mineralisation is associated with the development of a high temperature skarn assemblage of diopside, grossular–andradite garnet, actinolite, epidote and apatite. Sub-economic copper-bearing sulphide mineralisation overprints the magnetite mineralisation and is associated with deposition of hydrothermal calcite and the formation of an extensive sodium alteration halo dominated by albite and scapolite. Chlorite formation accompanies this stage and further later stage hydrothermal overprints. The replacement has in places resulted in preservation of primary features of the limestone, including fossils and sedimentary structures in magnetite, skarn calc-silicates and sulphides.Analysis of Re–Os isotopes in molybdenite indicates formation of the sulphide mineral assemblage at 336.2±1.3Ma, whilst U–Pb analyses of titanite from the skarn alteration assemblage suggests skarn alteration at 326.6±4.5Ma with re-equilibration of isotope systematics down to ~270Ma. Analyses of mineral assemblages, fluid inclusion microthermometry, O and S isotopes suggest initial mineralisation temperatures in excess of 600°C from hypersaline brines (45–50wt.% NaCl eq.), with subsequent cooling and dilution of fluids to around 150°C and 20wt.% NaCl eq. by the time of calcite deposition in late stage sulphide-bearing veins. δ18O in magnetite (−1.5 to +3.5‰) and skarn forming silicates (+5 to +9‰), δ18O and δ13C in limestone and skarn calcite (δ18O +5.4 to +26.2‰; δ13C −12.1 to +0.9‰) and δ34S in sulphides (−3.3 to +6.6‰) and sulphates (+4.9 to +12.9‰) are all consistent with the interaction of a magmatic-equilibrated fluid with limestone, and a dominantly magmatic source for S. All these data imply skarn formation and mineralisation in a magmatic–hydrothermal system that maintained high salinity to relatively late stages resulting in the formation of the large Na-alteration halo. Despite the reported presence of evaporites in the area there is no evidence for evaporitic sulphur in the mineralising system.These skarns show similarities to some members of the iron oxide–apatite and iron oxide–copper gold deposit classes and the model presented here may have implications for their genesis. The similarity in age between the Turgai deposits and the deposits of the Magnitogorsk zone in the western Urals suggests that they may be linked to similar magmatism, developed during post-orogenic collapse and extension following the continent–continent collision, which has resulted in the assembly of Laurussian terranes with the Uralide orogen and the Kazakh collage of the Altaids or Central Asian Orogenic Belt. This model is preferred to the model of simultaneous formation of very similar deposits in arc settings at either side of an open tract of oceanic crust forming part of the Uralian ocean.

Preconcentration strategies in the processing of nickel laterite ores part 3: Flotation testing

The preconcentration of nickel (Ni) laterite ores ahead of Ni recovery by hydrometallurgical processing makes good economic sense. Since Ni-bearing minerals are often finely disseminated through laterite ores, liberation of minerals either high and/or low in Ni content is a prerequisite prior to any form of separation process. It is the purpose of this paper to investigate the use of flotation to generate products either high or low in Ni-bearing minerals from a sample of Ni laterite with the generic description of “siliceous goethitic”. Previous attempts showed that upgrading of Ni laterites has only been conducted in laboratory or pilot plant scale, not adopted commercially. A number of feed preparation techniques ahead of flotation were attempted at laboratory scale on a sample of Ni laterite containing predominantly goethite and quartz. Flotation tests even on closely sized particles (38–75μm) failed to yield significant Ni upgrades using the reagents tested in this study, based on those used commercially for processing iron oxide ores. The best result was an increase in Ni content from 1.0% to 1.4% at a Ni recovery of 43%. This was obtained using 400g/t of an amine collector and 300g/t of starch at pH 10 on a sample of hydrocyclone underflow. This paper was designed to provide some lessons learnt for future researchers from laboratory flotation testing of a complex Ni laterite ore.

Method for Transformation of Weak Magnetic Minerals (Hematite, Goethite) into Strong Magnetic Mineral (Magnetite) to Improve the Efficiency of Technologies for Oxidized Iron Ore Beneficiation

Method for Transformation of Weak Magnetic Minerals (Hematite, Goethite) into Strong Magnetic Mineral (Magnetite) to Improve the Efficiency of Technologies for Oxidized Iron Ore Beneficiation

Reduction and oxidation kinetics of different phases of iron oxides

The redox properties and kinetic parameters of three different phases of as-received iron ores such as γ-FeOOH, Fe2O3, and Fe3O4 were investigated using isothermal experiments for reduction and oxidation reaction using hydrogen and H2O, respectively, to investigate the possibility for chemical looping process to produce pure hydrogen. Among the selected kinetic equations of three different iron oxide ores for the reduction at 800 °C and oxidation in the temperature ranges 700–850 °C, three-dimensional diffusion kinetic model such as Jander equation was well fitted with the experimental redox reactions of the three different iron ores. The calculated activation energies of iron ores with a main phase of γ-FeOOH, Fe2O3, and Fe3O4, for the oxidation reaction with H2O, were found to be around 21.5, 48.9, and 11.0 kJ/mol, respectively. The smaller activation energy and larger oxidation rate were observed on the Fe3O4–phase iron ore owing to its large reduction rate and stable particle size maintenance even under high temperature redox reactions, and it is suitable for the further application to chemical looping process.

Synthesis of Magnetite Nanoparticles by Top‐Down Approach from a High Purity Ore

This study attempts to synthesize magnetite nanoparticles from a high purity natural iron oxide ore found in Panvila, Sri Lanka, following a novel top‐down approach. Powder X‐Ray diffraction, elemental analysis, and chemical analysis data confirmed the ore to be exclusively magnetite with Fe2+ : Fe3+ ratio of 1 : 2. Surface modified magnetite nanoparticles were synthesized by destructuring of this ore using a top‐down approach in the presence of oleic acid. These oleic acid coated nanoparticles were further dispersed in ethanol resulting in stable nanomagnetite dispersion. Interestingly, the nanoparticles demonstrated a spherical morphology with a particle size ranging from 20 to 50 nm. Magnetic force microscopic data was used to confirm the topography of the nanoparticles and to study the magnetic domain structure.

Investigation of Combination of Variable Diameter Rod Elements in Rod Matrix on High Gradient Magnetic Separation Performance

Rod matrix is effectively applied to separate fine weakly magnetic particles in pulsating high gradient magnetic separation (PHGMS), due to its reliable operation, simple combination and resistance to mechanical entrainment. They are now used to beneficiate oxidized iron ores, ilmenite, and wolframite, etc., and to purify wastewater. The combination of variable diameters rod elements in rod matrix plays a decisive role in recovery most of the different size fractions of magnetic particles, thus generating a significant influence on the performance of PHGMS. Combination of variable diameter rod elements in rod matrix on PHGMS is investigated in combination of 3 mm and 2 mm rod elements in rod matrix, by Slice-Matrix Analysis (SMA); it was found that the recovery of combinatorial rod matrix is higher than single diameter of matrix on PHGMS.

Mapiquiroite, (Sr,Pb)(U,Y)Fe2 (Ti,Fe3+)18O38, a new member of the crichtonite group from the Apuan Alps, Tuscany, Italy

Mapiquiroite, (Sr,Pb)(U,Y)Fe 2 (Ti,Fe 3+ ) 18 O 38 , was identified as a new mineral from the baryte + pyrite + iron oxide ores of Buca della Vena (BdV) and Monte Arsiccio (MA) mines, Apuan Alps, Tuscany, Italy. At BdV, mapiquiroite occurs as complex rhombohedral or tabular pseudo-hexagonal crystals, up to 1 mm in size, black in colour, with a sub-metallic lustre, in quartz + ‘adularia’ + baryte veins embedded in schists, in association with allanite-(Ce), anatase, destinezite, gypsum, monazite-(Ce), pyrite, rutile, and ‘tourmaline’; at MA, mapiquiroite forms tabular pseudo-hexagonal crystals, up to 5 mm in size, in quartz + carbonate veins embedded in magnetite-rich dolostones, in association with baryte, boulangerite, derbylite, siderite, and sphalerite. Under the microscope, mapiquiroite is blackish in colour, weakly bireflectant, and non-pleochroic. Internal reflections are absent. Anisotropism is distinct, without characteristic rotation tints. Minimum and maximum reflectance data for COM wavelengths [λ (nm), R air (%); data for the specimens from BdV and MA, respectively] are: 471.1, 17.0/17.2 and 17.7/18.0; 548.3, 16.7/17.0 and 17.6/17.8; 586.6, 16.4/16.7 and 17.3/17.7; 652.3, 16.1/16.3 and 17.0/17.3. Vickers hardness is 750 kg · mm −2 and 782 kg·mm −2 for specimens from BdV and MA, respectively, corresponding to a Mohs’ hardness ~ 6. The chemical data point to the formulae (Sr 0.533 La 0.176 Pb 0.105 Na 0.030 Ca 0.026 ) ∑=0.870 (U 0.407 Ce 0.101 Y 0.205 Mn 0.072 ) ∑=0.785 Fe 3+ 2.000 (Ti 12.423 Fe 3+ 3.345 Cr 1.624 V 5+ 0.129 Al 0.032 Sn 0.013 Nb 0.007 ) ∑=17.573 O 38 (BdV) and (Sr 0.312 Pb 0.248 Na 0.019 Ca 0.014 La 0.009 ) ∑=0.602 (U 0.858 Y 0.070 Ce 0.021 Mn 0.005 ) ∑=0.954 (Fe 3+ 1.695 Zn 0.305 ) ∑=2.000 (Ti 12.070 Fe 3+ 4.987 V 5+ 0.372 Al 0.030 Nb 0.030 Cr 0.015 Sn 0.001 ) ∑=17.505 O 38 (MA). Mapiquiroite is trigonal, R 3, with a 10.3719(7), c 20.875(1) A, V 1944.8(2) A 3 and a 10.3854(3), c 20.8942(6) A, V 1951.7(1) A 3 for the specimens from BdV and MA, respectively. The crystal structures of mapiquiroite from these two occurrences were refined to R 1 = 0.028 and 0.032, respectively. Mapiquiroite is isostructural with other members of the crichtonite group. The name mapiquiroite honours four Italian mineral collectors, Riccardo Mazzanti, Luigi Pierotti, Ugo Quilici, and Moreno Romani for their contribution to the study of the mineralogy of baryte + pyrite + iron oxide deposits from the Apuan Alps.

Size recovery curves of minerals in industrial spirals for processing iron oxide ores

Spirals are gravity concentrators used for the concentration of coal, iron oxide ore and heavy minerals. As in any gravity concentrators the separation of minerals in a spiral is based on particle size and specific gravity. The size recovery curves of minerals in mineral processing equipment provide an efficient way to analyse the operation of spiral concentrators. However unlike other gravity concentrator equipment such as hydrocyclones or hydraulic classifiers a drop of recovery in the region of coarse particles is observed for spirals. This decrease of recovery of coarse particles is observed for the valuable and gangue minerals of roughing, cleaning and re-cleaning spirals of two Canadian iron ore concentrators. Any improvement in the recovery of coarse iron carrier particles can lead to a significant increase in the plant revenues.

Metallogenesis of the Zhibo and Chagangnuoer volcanic iron oxide deposits in the Awulale Iron Metallogenic Belt, Western Tianshan orogen, China

The Zhibo and Chagangnuoer iron ore deposits occur at the same volcanic edifice and are situated along the eastern segment of the Awulale Iron Metallogenic Belt in the Western Tianshan orogen of China. The former deposit is exposed near the caldera and the latter lies on the northwestern flank of the volcanic structure. The ore mineralization, the ore texture, the ore bodies structures, the trachytic to trachy andesitic host rocks and the geological characteristics of the Zhibo and Chagangnuoer deposits indicate a magmatic source for the iron oxide mineralization. This is supported by the observation that the vast majority of the Zhibo and Chagangnuoer magnetites have δ18O values between >+0.9‰ and <+4.00‰ consistent with a precipitation from ‘normal’ subduction type intermediate to felsic magmas or high-temperature magmatic fluids. However some magnetites with low δ18O values (<+0.9‰) are thought to have formed in equilibrium with a low to moderate temperature hydrothermal fluid as is evidenced by pervasive and vein-type controlled (skarn-type) alteration of the ore and host volcanic rocks. Furthermore, the trace element composition of the equilibrium ortho-magmatic magnetites was reset during this hydrothermal alteration event. Major and trace element characteristics indicate that the volcanic rocks, the granitoids and the iron ore bodies were formed in a continental arc setting during the Early Carboniferous. The ore-hosting volcanic rocks probably originated from melting of a mantle wedge that was metasomatized during subduction. Laser ablation-ICPMS (LA-ICPMS) U–Pb zircon ages of 350±2Ma and 361±7 Ma were obtained for zircon from the trachy andesitic host rock of the iron ore exposed near the caldera of the volcano and the highly altered fine grained garnet-dominated host rock on the flank of the volcano, respectively. A U–Pb zircon age of 321±2Ma was gained for the rhyolite overlying the ore bodies at the Chagangnuoer deposit, which were intruded by a granitic pluton with a U–Pb zircon age of 319±2Ma. Furthermore, the minerals of the skarn-type alteration zone at the Chagangnuoer deposit yield an Sm-Nd isochron age of 313±7Ma (Grt-Act-Epi-whole rock). Considering previous geochronological studies, a 350–330Ma age range as observed in the host rocks of the Zhibo mine is believed to display a period of continuous volcanic activity and associated ortho-magmatic, high-temperature iron oxide mineralization during subduction. The iron oxide mineralization in both deposits is thought to have been derived from the same magma source, as the ore-hosting volcanic rocks are similar to ‘Kiruna-type’ iron oxide ores. Subsequently, the volcanic host rocks and the iron ore bodies were variably hydrothermally altered during subduction (ca. 319–313Ma). The alteration zones were probably facilitated by the infiltration of hydrothermal fluids along faults, which were created by the intrusion of a granitic pluton.

Effect of wash water on the mineral size recovery curves in a spiral concentrator used for iron ore processing

Spiral concentrators are widely used in the iron ore industries to concentrate heavy iron oxides from light silica gangue minerals. The operation of a WW-6 spiral for the concentration of an iron oxide ore is analyzed through the size recovery or partition curves of the minerals. Several tests conducted following a factorial design using wash water addition, feed rate and slurry solid concentration as studied factors show that for the tested conditions the wash water addition has the most important effect on the spiral performance with its effect being mainly located on coarse particles.

Concentration on Limonitic Iron Ore by Multi-Grade Magnetic Roasting-Low Intensity Magnetic Separation

Magnetizing roasting followed by magnetic separation is a compound technique for the beneficiation optimization of Huangmei refractory limonite. The natural limonite samples are obtained from Huangmei, Hubei province. The samples are characterized by TG-DTG-DSC. The content of major components is analyzed by SEM-XRAY, which is found that the sample iron mainly occurs in the form of limonite, with impurities including quartz, kaolinite, and barite. The feasibility of oxidized iron ore magnetic roasting limonite by multi-grade dynamic state magnetizing roasting is investigated. The effects of operation parameters such as roasting atmosphere, temperature and roasting duration are analyzed. The results show that: in the condition of the volume fraction of CO is 2% to 5%, the temperature is 700-780°C, and the roasting duration is 20 to 30 minutes. By multi-grade dynamic state magnetizing roasting, the grade of roasting limonite is nearly 33%, and the feasibility of separation is effective. A good index is created through simple mineral processing, the iron grade of concentrate reaches to 60% and the iron recovery rate reaches to 83.94%. It reveals that the multi-grade dynamic state magnetizing roasting device has a remarkable effect on roasting limonite.

Mercury-arsenic sulfosalts from Apuan Alps (Tuscany, Italy). I. Routhierite, (Cu0.8Ag0.2)Hg2Tl(As1.4Sb0.6)Σ=2S6, from Monte Arsiccio mine: occurrence and crystal structure

Routhierite, ~ (Cu 0.8 Ag 0.2 )Hg 2 Tl(As 1.4 Sb 0.6 ) ∑=2 S 6 , was identified in the baryte + pyrite + iron oxide ore from Monte Arsiccio mine, Apuan Alps, Tuscany, Italy. Routhierite occurs as anhedral grains up to 0.5 mm in size forming veinlets embedded in pyrite-rich dolostones, in association with aktashite, baryte, boscardinite, cymrite, protochabourneite, pyrite, realgar, Hg-rich sphalerite, and stibnite. Rarely, euhedral crystals of routhierite were also observed in quartz+baryte+dolomite veins, with boscardinite, Hg-rich oversubstituted andorite, realgar, sphalerite, and Hg-rich tetrahedrite. Electron-microprobe data give (in wt%): Cu 4.79(7), Ag 2.00(5), Fe 0.12(1), Hg 37.31(23), Zn 0.98(1), Cd 0.11(7), Tl 19.19(16), As 9.96(31), Sb 7.16(35), S 18.86(7), Cl 0.05(1), total 100.53(18). The structural formula, based on (S + Cl) = 6 at., is (Cu 0.77 Ag 0.19 Fe 0.02 ) ∑=0.98 (Hg 1.89 Zn 0.15 Cd 0.01 ) ∑=2.05 Tl 0.96 (As 1.35 Sb 0.60 ) ∑=1.95 (S 5.99 Cl 0.01 ) ∑=6.00 . The crystal structure of routhierite from Monte Arsiccio mine was refined to R 1 = 0.030 in the I -42 m space group, with unit-cell parameters a 9.9780(5), c 11.3764(7) A, V 1132.6(1) A 3 . In the crystal structure of routhierite, (Cu,Ag)S 4 and (Hg,Zn)S 4 tetrahedra share corners to form a framework with channels parallel to [001] hosting TlS 6 and (As,Sb)S 3 polyhedra. The relatively short Tl–Tl distance (3.33 A) could indicate Tl–Tl interaction. Chemical and crystallographic data indicate the Sb-rich nature of routhierite from Monte Arsiccio mine. The Sb/(Sb + As) atomic ratio is 0.31, to be compared with 0.11–0.12 for routhierite from the type locality of Jas Roux, France. The Sb enrichment of this new occurrence is in agreement with the usual predominance of antimony in sulfosalts from hydrothermal ores of Apuan Alps.

Predictability of Removed Phosphorus Concentration during Microbial Leaching of Iron Oxide Ore Using Acidithiobacillus Ferrooxidans (ATF)

Predictability of removed phosphorus concentration was carried out based on multi-factorial influence of pH, resident time and as-beneficiated phosphorus content of the iron ore during microbial leaching with Acidithiobacillus Ferrooxidans. The model was expressed as; PR = 0.0042ϑ 3 - 0.0718 ϑ 2 + 0.3297 ϑ - 0.001₰ + 0.01γ - 0.0903 The validity of the multi-factorial model was found to be rooted on the expression PR + 0.001₰ - 0.01γ + 0.0903 = 0.0042ϑ 3 - 0.0718ϑ 2 + 0.3297 ϑ where both sides of the expression are correspondingly approximately equal. Statistical analysis of removed phosphorus concentration for each value of the bioleaching solution pH as obtained from experiment and derived model-predicted results show standard errors of 0.1031 and 0.1010% respectively. Furthermore, removed phosphorus concentration per unit solution pH as obtained from experiment and derived model-predicted results were 0.005 and 0.006 % respectively. The maximum deviation of model-predicted removed phosphorus concentration (from experimental result) was less 8%. This translates into a derived model confidence level of above 92%.

Open System Analysis of Bioextracted Iron during Leaching of Iron Oxide Ore using Acidithiobacillus Ferrooxidans

This paper presents an open systemic analysis of bioextracted iron during leaching of iron oxide ore using acidithiobacillus ferrooxidans. The analysis showed prediction of the concentration of bioextracted iron at varying initial bioleaching solution pH and as-beneficiated Fe content of the ore. An empirical model was derived, validated and used as a tool for the analysis. The validity of the polynomial model expressed as; ζ = 0.0077ϑ 3 - 0.1618 ϑ 2 + 0.9345ϑ + 0.0002₰ + 0.0931 was found to be rooted on the core expression ζ - 0.0002₰ - 0.0931 = 0.0077ϑ 3 - 0.1618 ϑ 2 + 0.9345ϑ where both sides of the expression are correspondingly approximately equal. Statistical analysis of the extracted iron concentration as obtained from experiment and derived model for each value of the initial bioleaching solution pH used shows standard errors of 0.3917 and 0.3780 respectively. Extracted iron concentrations per unit initial bioleaching solution pH as obtained from experiment and derived model are 0.0917 and 0.0784 %. Deviational analysis indicates that the maximum deviation of the model-predicted iron extraction (from experimental results) was less than 11%, implying a confidence level above 89%.

TG measurement of reactivity of candidate oxygen carrier materials

This study examined several candidate raw materials for use as the reactive agents in developing new oxygen carriers for chemical looping combustion. A thermogravimetric analyzer, Mettler TGA/DSC1, was used to measure oxygen capacity and relative reaction rates during oxidation and reduction cycles. The reactive gases used were 4 % hydrogen in inert gas for the reduction cycle and air for the oxidation cycle, with a nitrogen purge between reduction and oxidation cycles. Samples were typically tested for at least ten cycles to study any change in reactivity or oxygen capacity. Reaction temperatures tested ranged from 700 to 900 °C. Materials tested included an iron oxide ore, iron-based tailings from a metals extraction process, a nickel oxide supported on nickel aluminate and a copper oxide plus inert material system. The materials varied in their oxygen capacity, reactivity and the change in properties with repeat cycles. Of the samples tested, the NiO–NiAl2O4 oxygen carrier demonstrated the fastest reaction in reduction and oxidation and had stable properties over ten cycles. The iron oxide ore sample performance declined significantly with repeat cycles. The performance of the iron-based tailings declined slightly over the ten cycles. The addition of inert second phase materials to CuO improved the performance by inhibiting sintering of the oxide at the operating temperature. Although the reactivity of the tailings and iron hydroxide samples was not as high as the NiO based oxygen carrier, they are promising carrier materials due to their low cost and lower toxicity relative to nickel. Future experiments will look at CO and CH4 reduction reactions using the TG, surface characterization using SEM, XRD, and cyclic testing in a batch fluidized bed reactor.