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The leaching kinetics of 20CaO·13Al2O3·3MgO·3SiO2(Q phase) was studied in this paper. The effects of agitation speed, leaching temperature, concentration of sodium carbonate, particle size and liquid–solid ratio on alumina leaching ratio of Q phase were investigated. The results indicate that the agitation speed did not influence alumina leaching ratio when it was higher than 400 r min−1, and the effect of liquid film diffusion on the leaching process was eliminated. The alumina leaching ratio would not increase by changing the liquid–solid ratio, when the concentration of sodium carbonate was excessive. The leaching process of Q phase was better as both the temperature and the concentration of sodium carbonate were higher and the particle size was smaller. The effect of concentration of sodium carbonate on alumina leaching ratio was not obvious. The leaching kinetics followed the shrinking unreacted core model, the reaction order of leaching process of Q phase was 0.47, and it can be described by surface chemical reaction. The activation energy was 41.63 ± 10 kJ mol−1, and the frequency factor was 1.472 × 103. [ABSTRACT FROM AUTHOR]

The formation kinetics of 20CaO·13Al2O3·3MgO·3SiO2 (Q phase) have been studied with quantitative X-ray diffraction method under the reaction conditions of temperature range of 1300-1375°C and 6 h temperature holding time. The results indicated that 12CaO·7Al2O3 (C12A7) and 2O3 (CA) existed as intermediate phases and disappeared until the formation of Q phase was nearly completed. The formation temperature of Q phase is ∼1300°C, and its reaction equation is C2AS(C2S) + CA(CA2, C12A7) + f-MgO → Q phase. The solid-solid reaction kinetic model was used to fit the kinetic mechanism. It can be described fairly well by Ginstling-Brounstein equation. The apparent activation energy and preexponential factor for the reaction among CaCO3, Al2O3, MgO and SiO2 were respectively determined as 380 ± 10 kJ mol− 1 and 4·69 × 109 h− 1. [ABSTRACT FROM AUTHOR]

The formation kinetics of 20CaO·13Al2O3·3MgO·3SiO2 (Q phase) have been studied with quantitative X-ray diffraction method under the reaction conditions of temperature range of 1300-1375°C and 6 h temperature holding time. The results indicated that 12CaO·7Al2O3 (C12A7) and 2O3 (CA) existed as intermediate phases and disappeared until the formation of Q phase was nearly completed. The formation temperature of Q phase is ∼1300°C, and its reaction equation is C2AS(C2S) + CA(CA2, C12A7) + f-MgO → Q phase. The solid-solid reaction kinetic model was used to fit the kinetic mechanism. It can be described fairly well by Ginstling-Brounstein equation. The apparent activation energy and preexponential factor for the reaction among CaCO3, Al2O3, MgO and SiO2 were respectively determined as 380 ± 10 kJ mol− 1 and 4·69 × 109 h− 1. [ABSTRACT FROM AUTHOR]

In this paper, the operational envelops and efficiency maps of an electrically excited (EE) machine with/without employing flux weakening control via armature current and/or with/without the field excitation regulating are obtained and comprehensively compared for electric vehicle applications. It shows that even in EE machines, only using the field excitation regulating but without the flux weakening armature current control, the maximum power at high speed is not constant but inversely proportional to the machine speed. Only by employing the flux weakening armature current control, the maximum constant power operation at high-speed region can be achieved while the operational high-speed region can be greatly extended. The maximum efficiency in this extended high-speed region can be achieved when both the field excitation and flux weakening d -axis armature current change proportionally. The main benefit of the field excitation regulating is that the efficiency in low-torque region can be significantly improved. All the analyses are validated analytically. [ABSTRACT FROM AUTHOR]