Effect of Heating Rate on Pyrolysis Behavior and Kinetic Characteristics of Siderite

Abstract

The pyrolysis characteristics of siderite at different heating rates under the neutral atmosphere were investigated using various tools, including comprehensive thermal analyzer, tube furnace, X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive spectrometry (EDS) and vibrating specimen magnetometer (VSM) measurements. The reaction of siderite pyrolysis followed the one-step reaction under the neutral atmosphere: FeCO 3 → Fe 3 O 4 + CO 2 + CO. As the increasing of heating rate, the start and end pyrolysis temperatures and temperate where maximum weight loss rate occurred increased, while the total mass loss were essentially the same. Increasing heating rate within a certain range was in favor of shortening the time of each reaction stage, and the maximum conversion rate could be reached with a short time. The most probable mechanism function for non-isothermal pyrolysis of siderite at different heating rates was A 1/2 reaction model (nucleation and growth reaction). With increasing heating rate, the corresponding activation energies and the pre-exponential factors increased, from 446.13 to 505.19 kJ•mol −1 , and from 6.67 × 10 −18 to 2.40 × 10 −21 , respectively. All siderite was transformed into magnetite with a porous structure after pyrolysis, and some micro-cracks were formed into the particles. The magnetization intensity and specific susceptibility increased significantly, which created favorable conditions for the further effective concentration of iron ore.

Effect of CaF2 and CaO/Al2O3 ratio on evaporation and melting characteristics of low-fluoride CaF2–CaO–Al2O3–MgO–TiO2 slag for electroslag remelting

“…As the mass ratio continues to increase, the pre-reference factor increases obviously. The pre-reference factor reflects the collision degree of the reaction per minute, so the higher the A value is, the easier the evaporation reaction occurs [18], indicating that the addition of CaF 2 content and CaO/Al 2 O 3 mass ratio promotes the evaporation of slag, which is consistent with the experimental results.…”

“…where β is the heating rate, K s −1 . Substituting Equation (11) into Equation ( 9), the expression can be obtained as shown in Equation ( 12) [17][18][19][20][21][22][23].…”

Application of Artificial Neural Networks to Predict the Catalytic Pyrolysis of HDPE Using Non-Isothermal TGA Data

“…However, at high catalyst to polymer ratio, the effect of catalyst was dominating, and E values almost decreased as the ratio increased. Generally, E values increase as heating rate increases [28], and using catalysts increases the reaction rate and provides an opportunity for the reaction to occur at lower activation energy [29].…”

The Characterization and SCR Performance of Mn-Containing α-Fe2O3 Derived from the Decomposition of Siderite

“…According to previous studies, the main decomposition of siderite started at 478 • C and ended at 580 • C, with a maximum rate at 529 • C [31]. In this experiment, the natural siderite was almost in a stable state with a mass loss of roughly 1.13% before 400 • C. Then, a significant mass loss of approximately 30.94% occurred from 420 to 600 • C, which should be ascribed to the decomposition of siderite (FeCO 3 ) into Fe 2 O 3 [32]. According to the TG/DTG results, the calcination temperatures of 450, 500, 550, and 600 • C were selected for catalyst preparation.…”