The kinetic analysis for non-isothermal solid state reduction of nickel laterite ore by carbon monoxide was investigated at four different heating rates (5, 10, 15 and 20 K min 21 ). The mechanism function f(a) and kinetic parameters of the reduction process of nickel laterite ore were determined by the thermogravimetric curves using Coats-Redfern method, and the reduction mechanism of nickel laterite ore was analysed. The results indicated that the degree of conversion a could be considered as a function of the temperature, and heating rates had less effect. There was clear relationship between calculated values and measured values of the degree of conversion by mathematic model verification. The kinetic analysis for non-isothermal reduction of nickel laterite ore was divided into three stages for 200-600uC, 600-800uC and 800-950uC; activation energies were 32?16 kJ mol 21 for 200-380uC, 33?13 kJ mol 21 for 380-600uC respectively, for the initial stage, which was characterised by a very slowrate; activation energy was 60?78 kJ mol 21 for the middle stage, which was characterised by a very fast rate; the reduction of nickel laterite ore remained a sluggish process at the decaying stage, and the reaction was governed by the diffusion of oxygen. The mechanism function belonged to G-B equation with differential forms f(a)53/2[(12a) 21/3 21] at the initial stage, and that belonged to Avrami-Erofeer equation (n54) with differential form f(a)51/ 4(12a)[2ln(12a)] 23 at the middle stage.
A series of experiments have been carried out to investigate the direct melting reduction process of high phosphorus iron in a nitrogen atmosphere with non-isothermal heating. The weight loss factor of the iron ore can be considered as a function of the temperature in the reduction progress. The kinetic parameters of the model can be determined by the data in a single test with a non-isothermal heating rate. With the temperature increasing, the reduction process can be divided into decrystal water phase of limonite, the pre-reduced phase of hematite, and finally reduced phase. The final reduction can be divided into three sections. On this basis, functions of the reaction mechanism and apparent activation energy in each stage are expected to be investigated. Then, the compensation effect of the whole reaction process is presented. Finally, the relationship of apparent activation energy and pre-exponential factor are also analysed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.