Effect Of CaO Research Articles

On the Rate of the Reduction of Wustite, Magnetite and Hematite Containing Al2O3, CaO and MgO

The effects of CaO, Al2O3 and MgO, all as the foreign oxide, on the rate limiting step of the reduction of pellets from wustite to metallic iron and on the values of rate parameters are studied.It is confirmed that the reduction behavior of those pellets may be represented either by the unreacted core model or by the uniform reaction model, depending on which kinds of the foreign oxide and the iron oxide are present at the start. The mixed rate control equation of mass transfer in the gas phase, intraparticle gas diffusion, and chemical reaction may be applied to any iron oxides that contain CaO and to hematite and magnetite both containing Al2O3. On the other hand, the reduction rates of the pure iron oxides, wustite containing Al2O3 and any iron oxides containing MgO are controlled by the oxygen diffusion in the metallic iron shell.These results agree with the conclusion of the present authors' previous studies, namely, when a complex oxide that consists of an iron oxide and any one of those foreign oxides precipitates in wustite during reduction, wustite grains are reduced nontopochemically while pellets are reduced topochemically.

還元鉄の酸化挙動に及ぼすCaO,Al<SUB>2</SUB>O<SUB>3</SUB>の影響

還元鉄の酸化挙動に及ぼすCaO,Al<SUB>2</SUB>O<SUB>3</SUB>の影響

Al<SUB>2</SUB>O<SUB>3</SUB>, CaO, MgOを含むウスタイト, マグネタイト, ヘマタイトの還元速度について

The effects of CaO, Al2O3 and MgO, all as the foreign oxide, on the rate limiting step of the reduction of pellets from wustite to metallic iron and on the values of rate parameters are studied.It is confirmed that the reduction behavior of those pellets may be represented either by the unreacted core model or by the uniform reaction model, depending on which kinds of the foreign oxide and the iron oxide are present at the start. The mixed rate control equation of mass transfer in the gas phase, intraparticle gas diffusion, and chemical reaction may be applied to any iron oxides that contain CaO and to hematite and magnetite both containing Al2O3. On the other hand, the reduction rates of the pure iron oxides, wustite containing Al2O3 and any iron oxides containing MgO are controlled by the oxygen diffusion in the metallic iron shell.These results agree with the conclusion of the present authors' previous studies, namely, when a complex oxide that consists of an iron oxide and any one of those foreign oxides precipitates in wustite during reduction, wustite grains are reduced nontopochemically while pellets are reduced topochemically.

Effect of CaO, Al<SUB>2</SUB>O<SUB>3</SUB>, MgO and ZnO on the Activity of PbO in the Molten PbO–SiO<SUB>2</SUB> System

The e.m.f. measurements were carried out in the temperature range of 1173∼1323 K by means of the following galvanic cells employing solid electrolytes:Ni.NiO(s)/ZrO2+CaO/Pb.PbO−SiO2−MeO(1)where MeO is CaO, Al2O3, MgO and ZnO.From these experimental results, it was found that the activity of PbO in the molten PbO–SiO2 system was increased remarkably by the addition of CaO or MgO, considerably by ZnO and slightly by Al2O3.These experimental results were found to be in good agreement with the results of Richardson and Pillay on the PbO–SiO2–CaO, PbO–SiO2–MgO and PbO–SiO2–ZnO systems.

Effect of CaO, MgO, and SiO2 impurities on some properties of grade 2000NM1 ferrite

Effect of CaO, MgO, and SiO2 impurities on some properties of grade 2000NM1 ferrite

Effect of CaO on Sintering of MgO

Effect of CaO on Sintering of MgO

PbO-SiO<SUB>2</SUB>融体中のPbOの活量におよぼすCaO, Al<SUB>2</SUB>O<SUB>3</SUB>の影響について

PbO-SiO<SUB>2</SUB>融体中のPbOの活量におよぼすCaO, Al<SUB>2</SUB>O<SUB>3</SUB>の影響について

溶融珪酸塩中のFeOの活量

The activity of FeO (aFeo) in molten FeO-SiO2 system and the effect of CaO, Al2O3 or TiO2 upon aFeO have been studied at the equilibrium conditions among Fe-crucible, FeO in the molten silicates and CO-CO2 gas mixtures. The CO-CO2 gas mixtures having a fixed. Pco/Pco2 was bubbled in molten silicate to establish the equilibrium. The oxygen partial pressure (P02) of gas phase was determined continuously by emf measurement with a use of solid electrolyte ZrO2 (+CaO). When the emf values were no more changed, the establishment of equilibrium among three phases was attained. The aFeO can be calculated by following equations Fe (crucible) +1/2O2 (gas) =FeO (in silicate melts)ΔG°=-RT In aFeo/aFe· Po2 1/2The results indicate that the activities of FeO in FeO-SiO2 system were similar to those obtained by other workers, and ΔGmix was fitted well with the estimated values from Samis & Toop's theory.The aFeO in the ternary systems containing CaO, Al2O3 or TiO2 as the third component was higher than that in the binary system at the same FeO mol%. From the results of infrared absorption spectra of these glassy samples, the behavior of CaO, Al2O3 or TiO2 was discussed.

Garnet-orthopyroxene and orthopyroxene-clinopyroxene relationships in simple and complex systems

Use of simple mixing models of orthopyroxene and garnet solid solutions enables extrapolation of experimentally determined equilibria in the MgSiO3-Al2O3 system to uninvestigated parts of pressure-temperature-composition space. Apparent discrepancies in the experimental data for simple and multicomponent systems may be explained by considering the effect of CaO and FeO on reducing pyrope activity in the garnet solid solutions. Equilibration pressures of natural garnet-orthopyroxene assemblages may be calculated, provided temperatures are known, from a combination of the experimental data on the MgSiO3-Al2O3 system and analyses of coexisting natural phases. Despite the presence of a compositional gap in the system, the solubility of enstatite in diopside coexisting with orthopyroxene can also be approximately treated by an ideal solution model. An empirical approach has been developed to take account of Fe2+ on the orthopyroxene-clinopyroxene miscibility gap in natural systems in order to calculate equilibration temperatures of 2-pyroxene assemblages. The model presented reproduces almost all of the available experimental data for multicomponent systems to within 60° C.

The effect of CaO, Cr 2O 3, Fe 2O 3 and Al 2O 3 on the stability of spinel and garnet peridotites

The reaction pyroxene+spinel⇌garnet+olivine defines the boundary between low pressure spinel peridotite and high pressure garnet peridotite. Experimental determination in the four component system MgOCaOAl 2O 3SiO 2 indicates that the CaO content is critical in defining the position of the reaction boundary. Where orthopyroxene is the only pyroxene present, increasing the CaO content decreases the pressure at which the reaction occurs; where both pyroxenes are present changing the CaO content has no effect; and where clinopyroxene is the only pyroxene present, increasing the CaO content increases the pressure of the reaction. Experiments on analyzed clinopyroxenes, orthopyroxenes and spinels from ultramafic nodules, indicate that the reaction boundary moves to higher pressures with increasing Cr 2O 3 and Fe 2O 3, and decreasing Al 2O 3 contents. Variations in the trivalent oxide ratio may result in changes of the equilibrium reaction by as much as 10 kilobars. The results indicate that the composition of the mantle is critical in defining the position of the spinel-to-garnet-peridotite boundary, and leaves open the possibility that spinel and garnet peridotite may coexist throughout a wide depth within the earth's upper mantle.

The effect of CaO, SiO2 and Fe2O3 on the microstructure of the Magnesia Clinker, (I-II)

The effect of CaO, SiO₂ and Fe₂O₃ on the microstructure of the Magnesia Clinker, (I-II)

The Effects of CaO and SiO<sub>2</sub> on the produced Compound and the microstructure of magnesia clinker (I)

The Effects of CaO and SiO<sub>2</sub> on the produced Compound and the microstructure of magnesia clinker (I)