Papers by Keyword: Complex Oxide

Abstract: This work studied a decomposition and reduction of complex carbonate (sideroplesite) siderite lump ore from the Bakal’s deposit. The decomposition caused formation of complex oxides (Fe,Mg,Mn)O and (Fe,Mg,Mn)O·Fe₂O₃, and it preceded the Fe reduction; the weight loss during the decomposition process reached about 32%, being followed by the formation of a large number of pores. As the pores and micro-pores provide deep penetration of the carbon monoxide in the bulk of the ore lumps, it seemed that the pores would allow reduction of this ore without difficulties. However, during reduction experiments it was discovered that the distribution of the reduction process and formation of the metal phase were not connected with the pores’ distribution. The reduction process developed via an electrochemical mechanism, and the channels of the distribution of the reduction process were oxides of metals which were difficult to reduce under the presented experimental conditions; these oxides were mostly represented by the magnesia and silica compounds. The high rate of the iron reduction from the complex iron-manganese-magnesium oxides was explained by the high rate of distribution of the negatively charged anion vacancies forming on the surface of the oxide, due to reaction with a reducing agent.

Abstract: The mathematical description of the electron mechanism of reduction of metals from complex polymetallic types of ore has been suggested. The description of the mechanism was based on diffusion and thermal processes occurring in the phases of a reducing agent and an oxide, and chemical reactions on the surface of a phase boundary. The effect of the major physics-chemical parameters on the rate of formation and movement of the reducing vacancies was considered. The obtained model allows calculation of the process of metal reduction from the bulk of a complex oxide by using the approach of the electron mechanism, which considers the process of reduction not as the interaction of the reducing agent with molecule of the metal oxide, but as the interaction with the oxygen anion of a crystal lattice.

Abstract: The ion-exchanger Mg_0.5Ti_0.5PO₄ of spinel type was prepared by means of the solid state reaction crystallization method, and was acid-modified. This inorganic ion-exchanger(Mg_0.5Ti_0.5PO₄) has the saturation capacity of exchange for Li⁺ higher than those for other alkali ions, the saturation capacity of exchange for Li⁺ reaches to 5.4mmol/g, MgTi-750(H) has a higher selectivity of ion exchange for Li⁺ than for other alkali ions.

Abstract: The ion-exchanger Al_1.75Fe_1.25(PO4)₃ of spinel type was prepared by means of the solid state reaction crystallization method. Its ion-exchange properties for alkali ions such as saturation capacity of exchange and distribution coefficient were determined. Al_1.75Fe_1.25(PO4)₃ was characterized by virtue of X-ray diffraction method. This inorganic ion-exchanger (Al_1.75Fe_1.25(PO4)₃) has the saturation capacity of exchange for Li⁺ higher than those for other alkali ions, the saturation capacity of exchange for Li⁺ reaches to 7.1mmol/g, AlFe-720(H) has a higher selectivity of ion exchange for Li⁺ than for other alkali ions. These result show AlFe-720 (H) has better memory and selectivity of ion exchange, and higher capacity of ion exchange for Li⁺. It is a kind of prospective ionic sieve for Li⁺.

Abstract: The ion-exchanger Al3Ti(PO4)4.3333 of inverse spinel type was prepared by a solid state reaction crystallization method. The Li+ extraction/insertion with this material were investigated by X-ray, FT-IR spectroscopy, and Kd measurement, The chemical analysis showed that the Li+ extraction/insertion be progressed mainly by an ion-exchange mechanism. The acid treated samples had an ion exchange capacity of 8.2mmol/g for Li+. It had a memorial ion-sieve property for Li+.

Abstract: The ion-exchanger Al1.6667Ti(PO4)3 of inverse spinel type was prepared by means of the solid state reaction crystallization method. Its ion-exchange properties for alkali ions such as saturation capacity of exchange and distribution coefficient were determined. Al1.6667Ti(PO4)3 was characterized by virtue of X-ray diffraction method. This inorganic ion-exchanger has the saturation capacity of exchange for Li+ higher than those for other alkali ions, the saturation capacity of exchange for Li+ reaches to 6.6mmol/g.

Abstract: The ion-exchanger Al_0.6667Ti(PO₄)₂ of spinel type was prepared by means of the solid state reaction crystallization method. The extraction/insertion reaction with this material was investigated by X-ray, saturation capacity of exchange, and Kd measurement. The experimental results have proved that the acid-treated sample has a capacity of exchange 3.9mmol·g-1 for Li⁺ in the solution, The chemical analysis showed that the Li⁺ extraction/insertion progressed mainly by ion-exchange mechanism and surface adsorption.

Abstract: The ion-exchanger Li_0.6Zn_1.2PO₄ of spinel type was prepared by a solid state reaction crystallization method. The extraction/insertion reaction with this material was investigated by X-ray, saturation capacity of exchange, and Kd measurement. The experimental results have proved that the acid-treated sample has a capacity of exchange 2.4mmol•g^-1 for Li⁺ in the solution, The chemical analysis showed that the Li⁺ extraction/insertion progressed mainly by ion-exchange mechanism and surface adsorption.

Abstract: The ion-exchanger Li_0.8Zn_1.1PO₄ of spinel type was prepared by means of the solid state reaction crystallization method, and was acid-modified. This inorganic ion-exchanger(Li_0.8Zn_1.1PO₄) has the saturation capacity of exchange for Li⁺ higher than those for other alkali ions, the saturation capacity of exchange for Li⁺ reaches to 3.0mmol/g.

Abstract: The results of a new potentiometric technique for in situ diagnostics of self-propagating high-temperature synthesis (SHS) of different complex oxides are presented. This technique is based on electrochemical processes. The characteristic peaks attributed to the electric responses from cation streams of alkali, alkaline-earth and some elements of group VI are discovered and the respective routes of the corresponding chemical reactions found.