Reduction kinetics of mechanically activated hematite concentrate with hydrogen gas using nonisothermal methods
TL;DR: In this article, the reduction kinetics of both non-activated and mechanically activated hematite concentrate in a vibratory mill for different grinding periods have been studied using themogravimetry (TG).
About: This article is published in Thermochimica Acta.The article was published on 2007-03-15. It has received 65 citations till now. The article focuses on the topics: Hematite.
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TL;DR: In this article, a thermogravimetric analysis of the reduction of hematite (Fe2O3) in a continuous stream of CH4 (15, 20, and 35%) was conducted at temperatures ranging from 700 to 825°C over ten reduction cycles.
120 citations
TL;DR: In this article, the curing behavior of an industrial melamine-formaldehyde (MF) resin with four different commercial curing catalysts was analyzed from thermal studies using differential scanning calorimetry (DSC) and model-free kinetic analysis.
96 citations
TL;DR: In this article, the authors studied the mechanism of the hydrogen reduction of MoO3 to MoO2 using a two-interface model, the predicted curves of which agreed well with the experimental results.
Abstract: Kinetics and mechanism of the hydrogen reduction of MoO3 to MoO2 were studied in this work. The experimental findings confirmed that the reduction of MoO3 to MoO2 was a consecutive reaction with the intermediate product Mo4O11. The dual reactions (MoO3 → Mo4O11, Mo4O11 → MoO2) occurred simultaneously, and the rate of the first reaction was higher than that of the second one. The reduction kinetics of MoO3 was analyzed according to a two-interface model, the predicted curves of which agreed well with the experimental results. Using this model, the rate controlling steps and the corresponding activation energies were obtained.
90 citations
TL;DR: In this paper, the reduction kinetics of α-Fe2O3 to metallic iron by carbon monoxide at temperatures of 1023 to 1223 K were experimentally investigated in a micro fluidized bed reactor with in-situ mass spectrometer analysis of product gases.
88 citations
TL;DR: In this article, the authors used biochar derived from walnut shell as a green reductant to reduce iron phase in the waste copper slag and realize the clean utilization of hazardous waste.
55 citations
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10,842 citations
TL;DR: In this article, a thermocouple is used to measure the sample temperature in a Stanton HT-D thermobalance, the bead of which is positioned in or near the sample, depending on crucible design.
Abstract: THE use of thermogravimetric data to evaluate kinetic parameters of solid-state reactions involving weight loss (or gain) has been investigated by a number of workers1–4. Freeman and Carroll2 have stated some of the advantages of this method over conventional isothermal studies. To these reasons may be added the advantage of using one single sample for investigation. However, the importance of procedural details, such as crucible geometry, heating rate, pre-history of sample, and particle size, on the parameters has yet to be fully investigated. It is also necessary to ensure accurate temperature measurement, both for precision and also to detect any departure from a linear heating rate due to endo- or exo-thermic reactions. (The effect of these may be largely eliminated by the use of small samples.) In our present work (using a Stanton HT–D thermobalance) the sample temperature is measured directly by means of a thermocouple the bead of which is positioned in or near the sample, depending on crucible design, the wires of which run down a twin-bore rise rod. The connexion between the end of the thermocouple wires on the balance arm and the terminal block is made by 0.001 in. platinum and platinum/rhodium wires5. It has been shown that these wires do not affect the performance of the balance but act merely as a subsidiary damping. From the terminal block compensated cable leads to the cold junction and a potentiometric arrangement for direct measurement of the thermocouple output.
5,770 citations
TL;DR: In this paper, a new method of obtaining the kinetic parameters from thermogravimetric curves has been proposed, which is simple and applicable to reactions which can not be analyzed by other methods.
Abstract: A new method of obtaining the kinetic parameters from thermogravimetric curves has been proposed. The method is simple and applicable to reactions which can not be analyzed by other methods. The effect of the heating rate on thermogravimetric curves has been elucidated, and the master curve of the experimental curves at different heating rates has been derived. The applications of the method to the pyrolyses of calcium oxalate and nylon 6 have been shown ; the results are in good agreement with the reported values. The applicability of the method to other types of thermal analyses has been discussed, and the method of the conversion of the data to other conditions of temperature change has been suggested. From these discussions, the definition of the thermal stability of materials has been criticized.
5,622 citations
Book•
01 Jan 1996
TL;DR: Sintering Measurement Techniques Solid-State Sintering Fundamentals as discussed by the authors Microstructure and Processing Relations in Solid-state Sinterings, Mixed Powders, Pressure-Assisted SinterING.
Abstract: Sintering Measurement Techniques. Solid-State Sintering Fundamentals. Microstructure and Processing Relations in Solid-State Sintering. Solid-State Sintering of Mixed Powders. Liquid-Phase Sintering. Pressure-Assisted Sintering. Novel Sintering Techniques. Sintering Atmospheres. Sintering Practice. Future Directions. Appendix. Index.
2,261 citations
01 Nov 1966-Journal of Research of the National Bureau of Standards Section A: Physics and Chemistry
TL;DR: It is concluded that methods involving a variable rate of heating or involving several thermogravimetric traces at different rates of heating are capable of establishing the uniqueness of kinetic parameters.
Abstract: Theoretical equations are developed for typical decompositions of polymers including those in which the volatilization does not follow a simple "reaction order" and those made up of a composite of several reactions of differing energies of activation. The effects of order, activation energy, heating rate and temperature dependence upon the calculated thermograms is illustrated. The literature on thermogravimetric kinetics is critically reviewed and coalesced into a logical and coherent development stressing the interrelation of methods and employing a consistent system of notation. As a result, a number of improved methods and new methods for the analysis of kinetic data applicable to the complex systems mentioned above are developed. It is concluded that methods involving a variable rate of heating or involving several thermogravimetric traces at different rates of heating are capable of establishing the uniqueness of kinetic parameters. A new method of determining initial parameters from rate-conversion data is developed. A novel concept is employed of programming reaction variables (in this case, the heating rate) in a manner which greatly simplifies the mathematics of the kinetic system and which shows promise of a wide range of applicability in the area of rate processes.
1,644 citations