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1.
High alumina and silica content in the iron ore affects coke rate, reducibility, and productivity in a blast furnace. Iron ore is being beneficiated all around the world to meet the quality requirement of iron and steel industries. Choosing a beneficiation treatment depends on the nature of the gangue present and its association with the ore structure. The advanced physicochemical methods used for the beneficiation of iron ore are generally unfriendly to the environment. Biobeneficiation is considered to be ecofriendly, promising, and revolutionary solutions to these problems. A characterization study of Salem iron ore indicates that the major iron-bearing minerals are hematite, magnetite, and goethite. Samples on average contains (pct) Fe2O3-84.40, Fe (total)-59.02, Al2O3-7.18, and SiO2-7.53. Penicillium purpurogenum (MTCC 7356) was used for the experiment. It removed 35.22 pct alumina and 39.41 pct silica in 30 days in a shake flask at 10 pct pulp density, 308 K (35 °C), and 150 rpm. In a bioreactor experiment at 2 kg scale using the same organism, it removed 23.33 pct alumina and 30.54 pct silica in 30 days at 300 rpm agitation and 2 to 3 l/min aeration. Alumina and silica dissolution follow the shrinking core model for both shake flask and bioreactor experiments.  相似文献   

2.
The formation of silico-ferrite of calcium and aluminum (SFCA) and SFCA-I iron ore sinter phases during heating and cooling of synthetic iron ore sinter mixtures in the range 298?K to 1623?K (25?°C to 1350?°C) and at oxygen partial pressure of 5?×?10?3 atm has been characterized using in situ synchrotron X-ray diffraction. SFCA and SFCA-I are the key bonding phases in iron ore sinter, and an improved understanding of their formation mechanisms may lead to improved efficiency of industrial sintering processes.?During heating, SFCA-I formation at 1327?K to 1392?K (1054?°C to 1119?°C) (depending on composition) was associated with the reaction of Fe2O3, 2CaO·Fe2O3, and SiO2. SFCA formation (1380?K to 1437?K [1107?°C to 1164?°C]) was associated with?the reaction of CaO·Fe2O3, SiO2, and a phase with average composition 49.60, 9.09, 0.14, 7.93, and 32.15?wt pct Fe, Ca, Si, Al, and O, respectively. Increasing Al2O3 concentration in the starting sinter mixture increased the temperature range over which SFCA-I was stable before the formation of SFCA, and it stabilized SFCA to a higher temperature before it melted to form a Fe3O4?+?melt phase assemblage (1486?K to 1581?K [1213?°C to 1308?°C]). During cooling, the first phase to crystallize from the melt (1452?K to 1561?K [1179?°C to 1288?°C]) was an Fe-rich phase, similar in composition to SFCA-I, and it had an average composition 58.88, 6.89, 0.82, 3.00, and 31.68?wt pct Fe, Ca, Si, Al, and O, respectively. At lower temperatures (1418?K to 1543?K [1145?°C to 1270?°C]), this phase reacted with melt to form SFCA. Increasing Al2O3 increased the temperature at which crystallization of the Fe-rich phase occurred, increased the temperature at which crystallization of SFCA occurred, and suppressed the formation of Fe2O3 (1358?K to 1418?K [1085?°C to 1145?°C]) to lower temperatures.  相似文献   

3.
Equilibrium measurements of the distribution of Fe, Ni, Sb, and Sn between a liquid Cu-O solution and a CaF2-CaO-MgO-SiO2 were carried out at 1500 K in a magnesia crucible. The results show that the studied solutes were in the states Fe(III), Ni(II), Sb(III), and Sn(IV), in the slag, for metal O contents ranging from 100 ppm to saturation at 2.1 pct. The Cu oxide solubility in the slag was also measured in absence of the solute elements. Its maximum solubility is about 4 ± 1 mass pct Cu2O. The compositions at equilibrium allow determination of the activity coefficients (referred to pure oxide) of the four solute oxides in the slag. These values, expressed in round figures to take into account the experimental uncertainties, are 10 for Fe2O3, 20 for NiO, 10 for SnO2, 1.6 10−2 for SbO1.5, and 60 for Cu2O.  相似文献   

4.
Isothermal sections of the Al-Cu-Fe equilibrium phase diagram at temperatures from 680 °C to 800 °C were determined in the region with 50 to 75 at. pct Al and 0 to 25 at. pct Fe using scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) techniques. This re- gion includes the face-centered icosahedral phase (Ψ-Al6Cu2Fe) which has unprecedented struc- tural perfection and no apparent phason strain. The icosahedral phase has equilibrium phase fields with four distinct phases at 700 °C and 720 °C (β-Al(Fe, Cu), λ-Al13Fe4, ω-Al7Cu2Fe, and liquid) and three phases at 680 °C(β, ω, and λ) and 800 °C (β, λ, and liquid). The B2 ordered β phase has considerably greater solubility for Cu than previously reported, extending from AlFe to ∼Al50Fe5Cu45. The equilibrium range of composition for the icosahedral phase at these temperatures was determined, and a liquidus projection is proposed.  相似文献   

5.
In this study, we investigated the separation of iron and scandium from Sc-bearing red mud. The red mud object of our study contained 31.11 wt% total iron (TFe), 0.0045 wt% Sc, hematite (Fe2O3) and ferrosilite (FeO·SiO2) as the main Fe-bearing minerals. The Sc-bearing red mud was treated by a novel deep reduction roasting and magnetic separation process that includes the addition of coke and CaO to extract Fe and enriching Sc from the Sc-bearing red mud. The addition of coke and CaO enhances the transformation of hematite (Fe2O3) to metallic iron (Fe0) and magnetite (Fe3O4) as well as the transformation of ferrosilite into metallic iron (Fe0). The test results show that utilizing the new process a Fe concentrate with a TFe content of 81.22 wt% and Fe recovery of 92.96% was obtained. Furthermore, magnetic separation tailings with Sc content of 0.0062 wt% and Sc recovery of 98.65% were also obtained. The test results were achieved under the following process conditions: roasting temperature of 1373 K, roasting time of 45 min, calcium oxide dosage of 20 wt%, coke dosage of 25 wt%, grinding fineness of 90% < 0.04 mm, and magnetic field intensity of 0.24 T. The major minerals in the Fe concentrate are metallic iron (Fe0) and magnetite (Fe3O4). The main minerals in the magnetic separation tailings with a low TFe content of 2.62% are CaO·SiO2, Na2O·SiO2, FeO·SiO2, Ca3Fe2Si3O12, CaAl2SiO6 and CaFe(SiO3)2.  相似文献   

6.
The reported experimental work on the systems Fe-Zn-O and Fe-Zn-Si-O in equilibrium with metallic iron is part of a wider research program that combines experimental and thermodynamic computer modeling techniques to characterize zinc/lead industrial slags and sinters in the system PbO-ZnO-SiO2-CaO-FeO-Fe2O3. Extensive experimental investigations using high-temperature equilibration and quenching techniques followed by electron probe X-ray microanalysis (EPMA) were carried out. Special experimental procedures were developed to enable accurate measurements in these ZnO-containing systems to be performed in equilibrium with metallic iron. The systems Fe-Zn-O and Fe-Zn-Si-O were experimentally investigated in equilibrium with metallic iron in the temperature ranges 900 °C to 1200 °C (1173 to 1473 K) and from 1000 °C to 1350 °C (1273 to 1623 K), respectively. The liquidus surface in the system Fe-Zn-Si-O in equilibrium with metallic iron was characterized in the composition ranges 0 to 33 wt pct ZnO and 0 to 40 wt pct SiO2. The wustite (Fe,Zn)O, zincite (Zn,Fe)O, willemite (Zn,Fe)2SiO4, and fayalite (Fe,Zn)2SiO4 solid solutions in equilibrium with metallic iron were measured.  相似文献   

7.
Ferropericlase (Mg1–x Fe x )O solid solution was prepared by ball milling of the mixture of MgO with a rock-salt structure and metal Fe powders in atmosphere and at room temperature. Differing from (Mg1–x Fe x )O prepared at high temperature by using MgO and FeO as starting materials, the solution of Fe in MgO is not continuous but limited in the ball milling process, and the solubility limit is less than 30 at. pct. About 92 pct of the Fe ions occupy the site of tetrahedral oxygen coordination in trivalent Fe (Fe3+) with high spin, whereas about 8 pct of the Fe ions occupy the site of octahedral oxygen coordination in bivalent Fe (Fe2+) with high spin. The Fe3+ and Fe2+ ions do not show a ferromagnetic but show a paramagnetic state. The as-milled (Mg1–x Fe x )O is metastable and decomposes to ferropericlase (Mg1–y Fe y )O (where y < x) and MgFe2O4 with spinel structure as annealed above 773 K (500  °C), and the content of Fe in the (Mg1–y Fe y )O increases with increasing annealing temperature. A bulk (Mg1–x Fe x )O was fabricated by annealing the as-milled (Mg1–x Fe x )O powders at 973 K (700  °C). It shows n-type conductivity, which is attributed to an electronic small polaron with an activation energy of 0.135 eV.  相似文献   

8.
Copper smelting slag contains less than 2 mass pct of Cu oxide and 30–50 mass pct of FexO. Each year, the grade of copper ore decreases, while the amount of slag generated in the copper smelting process increases. In this study, a coupled reaction model to simulate the reaction between multicomponent slag and FeS-based matte was developed using reported thermodynamic data and double-film theory for the recycling of copper smelting slag. The activity coefficients of oxides in the multicomponent slag were calculated using a regular solution. The activity coefficients of Cu2O in the slag and those of FeS, Cu2S, and CaS in the FeS-based matte used previously reported data. The behaviors of Cu in slag and matte were confirmed by comparing the simulated results and the reported solubility of Cu in the slag in the temperatures ranging from 1473 K to 1573 K. In addition, the effect of the input amount of FeS on the copper content of the slag was verified by comparing the results of reaction model to experimental results. Using the reaction model, the influences of the initial ratio of FeO/SiO2 of the slag, temperature, and matte composition on the behaviors of Cu in the slag and matte were investigated.  相似文献   

9.
Hydrolytic stripping is the process whereby metal ions in a loaded solvent extractant are directly precipitated as oxides or hydroxides by hydrolysis with water, typically at 130° to 200 °C. Hydrolytic stripping tests were carried out in sealed tubes at 200 °C on Versatic 10 solutions of Mg, Ca, Sr, Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Cd, singly and in mixtures. Single solutions of Fe, Ni, Cu, Mg, and Mn precipitated αFe2O3, Ni(OH)2, CuO + Cu2O, Mg(OH)2, and γMn2O3, respectively, during testing. Several mixtures of iron with other metals precipitated magnetic spinel ferrites, MFe2O4. No other combinations of metals formed crystallographically distinctive mixed oxides.  相似文献   

10.
Calcium oxide favors greatly the reduction of metal sulfides by H2 at 800°C. Copper sulfides and copper-iron sulfides are reduced rapidly to metals: Cu2S+H2+CaO→2Cu+CaS+H2O CuS+H2+CaO→Cu+CaS+H2O Cu5FeS4+4H2+4CaO→5Cu+ Fe+4CaS+4H2O The reduction of chalcopyrite takes place according to any of the following reactions depending on the amount of CaO added: Cu2S·Fe2S3+H2+CaO→Cu2S·2FeS+CaS+H2O Cu2S·Fe2S3+3H2+3CaO→Cu2S+2Fe+3CaS+3H2O Cu2S·Fe2S3+4H2+4CaO→2Cu+2Fe+4CaS+4H2O Gravity and magnetic methods were not successful in separating the reaction products. However, leaching by dilute HCl was successful in eliminating CaS and iron (as FeS as well as metal) leaving behind Cu2S concentrate or metallic copper, respectively. Reduction of molybdenite is also influenced by the presence of CaO, but that of pentlandite is not. FATHI HABASHI and RAYMOND DUGADALE, formerly with the Research Division of the Anaconda Company, Tucson, Arizona  相似文献   

11.
The activities of SiO2 and Al2O3 in CaO-SiO2-Al2O3-MgO slags were determined at 1873 K along the liquidus lines saturated with 2CaO · SiO2, 2(Mg,Ca)O · SiO2, MgO, and MgO · Al2O3 phases using a slag-metal equilibration technique. Based on these and previous results obtained in ternary and quaternary slags, the isoactivity lines of SiO2 and Al2O3 over the liquid region on the 0, 10, 20, 30, and 40 mass pct Al2O3 planes and those on the 10 and 20 mass pct MgO planes were determined. The activity coefficients of Fe t O and MnO, the phase boundary, and the solubility of MgO were also determined.  相似文献   

12.
In order to elucidate the reaction mechanism between high Mn-high Al steel such as twin-induced plasticity steel and molten mold flux composed mainly of CaO-SiO2 during continuous casting process, a series of laboratory-scale experiments were carried out in the present study. Molten steel and molten flux were brought to react in a refractory crucible in a temperature range between 1713 K to 1823 K (1440 °C to 1550 °C) and composition evolution in the steel and the flux was analyzed using inductively coupled plasma atomic emission spectroscopy, X-ray fluorescence, and electron probe microanalysis. The amount of SiO2 in the flux was significantly reduced by Al in the steel; thus, Al2O3 was accumulated in the flux as a result of a chemical reaction, 4[Al] + 3(SiO2) = 3[Si] + 2(Al2O3). In order to find a major factor which governs the reaction, a number of factors ((pct CaO/pct SiO2), (pct Al2O3), [pct Al], [pct Si], and temperature) were varied in the experiments. It was found that the above chemical reaction was mostly governed by [pct Al] in the molten steel. Temperature had a mild effect on the reaction. On the other hand, (pct CaO/pct SiO2), (pct Al2O3), and [pct Si] did not show any noticeable effect on the reaction. Apart from the above reaction, the following reactions are also thought to happen simultaneously: 2[Mn] + (SiO2) = [Si] + 2(MnO) and 2[Fe] + (SiO2) = [Si] + 2(FeO). These oxide components were subsequently reduced by Al in the molten steel. Na2O in the molten flux was gradually decreased and the decrease was accelerated by increasing [pct Al] and temperature. Possible reactions affecting the Al2O3 accumulation are summarized.  相似文献   

13.
The activities of iron and copper and the solubilities of oxygen in copper-iron-sulfur-oxygen mattes have been determined by equilibrating mattes with CO−CO2−SO2 gas mixtures of fixed partial pressures of oxygen and sulfur and equilibrating a small mass of platinum with the melt. Iron and copper transferred from the matte to form a platinum-iron-copper alloy in which the activities of iron and copper are the same as in the matte. The activities of iron and copper in the matte were then determined from knowledge of the activities of iron and copper in the system platinum-iron-copper. Sulfides ofW Fe=0.1, 0.3, and 0.5 were studied, whereW Fe=wt pct Fe/(wt pct Fe+wt pct Cu), and sulfur pressures of 0.005, 0.0158, and 0.025 atm and oxygen pressures of 3.16×10−10, 7.94×10−10, 2.00×10−9, and 3.16×10−9 were used. The activity of copper, which varied in the range 0.06 to 0.165, decreases with increasingp O 2 at constantW Fe andp S 2 and decreases with increasingp S 2 at constantW Fe and constantp O 2. The activity of iron, which varied in the range 0.002 to 0.06, increases with increasingp O 2 at constantW Fe andp S 2 and decreases with increasingp S 2 at constantW Fe andp O 2. The activities of the components Cu2S, FeS, Cu2O, FeO, and Fe3O4 were calculated from the activities of iron and copper, the partial pressures of oxygen and sulfur, and the approapriate equilibrium constants. The variations of the activities of these components with matte grade, oxygen pressure, and sulfur pressure are presented and discussed. Within the range of experimental conditions studied, the solubility of oxygen in the melts is given by wt pct O=2.59pO2/0.225pS2/−0.18 (1+9.0W Fe)1.86  相似文献   

14.
The present study delivered the measurements of viscosities in SiO2-“FeO”-Al2O3 system in equilibrium with metallic Fe. The rotational spindle technique was used in the measurements at the temperature range of 1473 K to 1773 K (1200 °C to 1500 °C). Molybdenum crucibles and spindles were employed in all measurements. The Fe saturation condition was maintained by an iron plate placed at the bottom of the crucible. The equilibrium compositions of the slags were measured by EPMA after the viscosity measurements. The effect of up to 20 mol. pct Al2O3 on the viscosity of the SiO2-“FeO” slag was investigated. The “charge compensation effect” of the Al2O3 and FeO association has been discussed. The modified quasi-chemical viscosity model has been optimized in the SiO2-“FeO”-Al2O3 system in equilibrium with metallic Fe to describe the viscosity measurements of the present study.  相似文献   

15.
The viscosity of smelting slags from the Glogow copper plant in Poland was measured using a concentric cylinder viscometer. These slags contain typically 45 pct SiO2, 16 pct CaO, 8 pct MgO, 11 pct Al2O3, and only 5 to 7 pct total iron. The viscosity was measured as a function of the CaO, MgO, SiO2, Cu2O, Cr2O3, and Fe3O4 contents in the temperature range from 1473 to 1623 K. Silica and chromium oxide additions increased the viscosity, while small additions of the other oxides decreased the viscosity. However, at large additions of CaO or MgO, cooling resulted in a rapid increase in the viscosity upon reaching the transition temperature. This critical transition temperature increased with increasing additions of CaO and MgO. This was explained by the precipitation of solid particles upon reaching the saturation limit. Depending on the slag composition, the activation energy for viscous flow was found to be in the range from 200 to 370 kJ/mol.  相似文献   

16.
The fluidized bed sulfation roasting process followed by water leaching was investigated as an alternative process to treat nickel sulfide concentrate for nickel production. The effects of several roasting parameters, such as the sulfation gas flow rate, roasting temperature, the addition of Na2SO4, and the roasting time, were studied. 79 pct Ni, 91 pct Cu, and 95 pct Co could be recovered with minimal dissolution of Fe of 4 pct by water leaching after two-stage oxidation-sulfation roasting under optimized conditions. The sulfation roasting mechanism was investigated, showing that the outermost layer of sulfate melt and the porous iron oxide layer create a favorable sulfation environment with high partial pressure of SO3. Sulfation of the sulfide core was accompanied by the conversion of the sulfide from Ni1?x S to Ni7S6 as well as inward diffusion of the sulfation gas.  相似文献   

17.
The Knudsen cell-mass spectrometer combination has been used to study the Fe?Cu and Fe?Cu?C(sat) alloys at 1600°C. Activity coefficients in the Fe?Cu system are closely represented by the equations $$\begin{gathered} \ln \gamma _{Fe} = 1.86N_{Cu}^2 + 0.03, (0< N_{Fe}< 0.7) \hfill \\ \ln \gamma _{Cu} = 2.25N_{Fe}^2 - 0.19, (0.7< N_{Fe}< 1.0) \hfill \\ \end{gathered} $$ with an uncertainty in the quadratic terms of about 5 pct. For the iron-rich carbon-saturated alloys, the activity coefficient of copper is given by the equation $$\ln \gamma _{Cu} = 2.45(N'_{Fe} )^2 + 0.3N'_{Fe} + 0.03, (0< N'$$ to within an uncertainty of about 10 pct. N Fe represents the fraction NFe/(NFe+NCu), etc. The activity coefficient of iron in this region is found to be essentially constant at 0.69±0.05.  相似文献   

18.
In this article, mineralogical phase changes and structural changes of iron oxides and phosphorus-bearing minerals during the direct reduction roasting process were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). It has been found that the reduction of hematite follows the following general pathway: Fe2O3 → Fe3O4 → FeO → Fe. The last step of the reduction process contains two side reactions: either FeO → Fe2SiO4 → Fe or FeO → FeAl2O4 → Fe depending on the micro mineralogical makeup of the ore. In the reduction process of FeO → Fe, oolitic structure was destroyed completely and fluorapatite was diffused into gangue while metallic phase is coarsening at temperatures below 1200°C. Therefore, the separation of phosphorus-bearing gangue and metallic iron can be achieved by wet grinding and magnetic separation, and low phosphorus content metallic iron powder can be obtained. However, when the temperature reached 1250°C and beyond, some of the fluorapatite was reduced to elemental P and diffused into the metallic iron phase, making the P content higher in the metallic iron powder.  相似文献   

19.
A mineralogical study was carried out on the neutral leach residue and weak acid leach residue generated from Gordonsville zinc concentrate at the Clarksville Electrolytic Zinc Plant of Savage Zinc Inc. The intent was to characterize the mineral forms and associations of germanium. The Gordonsville zinc concentrate consists mostly of sphalerite which has a solid solution Ge content of ~400 ppm; the sphalerite is the dominant, if not only, Ge carrier in the concentrate. The neutral leach residue consists principally of iron gel-silica gel, ZnO, and basic zinc sulfate, (Zn,Cu)4(SO4)(OH)6·4H2O, together with minor amounts of ZnFe2O4, sphalerite, Zn2SiO4, Zn-Fe-Pb silicate, and PbSO4, as well as traces of quartz, silicates, Pb-K jarosite solid solution, Fe2O3, and FeO·OH. The major Ge carrier is the iron gel-silica gel phase, but modest amounts of Ge are present in the ZnO, ZnFe2O4, sphalerite, and Zn-Fe-Pb silicate phases. The weak acid leach residue consists mostly of iron gel-silica gel, ZnFe2O4, PbSO4, Pb-K jarosite, Zn-Fe-Pb silicate, and quartz. The major Ge carrier is the iron gel-silica gel phase which contains up to 1.7 pct Ge and accounts for ~70 pct of the total Ge content of this residue. The remaining Ge is carried by the Zn-Fe-Pb silicate, ZnFe2O4, and some of the rare Mn-Pb-Fe oxide phases.  相似文献   

20.
The phosphate-enrichment behavior has experimentally been investigated in CaO-SiO2-FeO-Fe2O3-P2Osteelmaking slags. The reaction ability of structural units in the slags has been represented the mass action concentration \( N_{i} \) from the developed ion and molecule coexistence theory (IMCT)- \( N_{i} \) model based on the IMCT. The defined enrichment possibility \( N_{{{\text{c}}i{\text{ {-}c}}j}} \) and enrichment degree \( R_{{{\text{c}}i{\text{{-}c}}j}} \) of solid solutions containing P2Ofrom the developed IMCT- \( N_{i} \) model have been verified from the experimental results. The effects of binary basicity, the mass percentage ratio \( {{ ( {\text{pct Fe}}_{t} {\text{O)}}} \mathord{\left/ {\vphantom {{ ( {\text{pct Fe}}_{t} {\text{O)}}} { ( {\text{pct CaO)}}}}} \right. \kern-0pt} { ( {\text{pct CaO)}}}} \) , and mass percentage of P2Oin the initial slags on phosphate-enrichment behavior in the slags has also been discussed. The results show that the P2Ocomponent can easily be bonded by CaO to form tricalcium phosphate 3 CaO·P2O5, and the formed 3CaO·P2Ocan react with the produced dicalcium silicate 2CaO·SiOto generate solid-solution 2CaO·SiO2-3CaO·P2Ounder fixed cooling conditions. The maximum value of the defined enrichment degree \( R_{{{\text{C}}_{ 2} {\text{S{-}}} {\text{C}}_{ 3} {\text{P}}}} \) of solid-solution 2CaO·SiO2-3CaO·P2Ois obtained as 0.844 under conditions of binary basicity as 2.5 and the mass percentage ratio \( {{ ( {\text{pct Fe}}_{t} {\text{O)}}} \mathord{\left/ {\vphantom {{ ( {\text{pct Fe}}_{t} {\text{O)}}} { ( {\text{pct CaO)}}}}} \right. \kern-0pt} { ( {\text{pct CaO)}}}} \) as 0.955 at fixed cooling conditions.  相似文献   

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