Effects of Iron Ores on the Pyrolysis Characteristics of a Low-Rank Bituminous Coal

Abstract

This work investigates the effects of two kinds of iron ore on the pyrolysis characteristics of a low-rank bituminous coal from Hami, China. The pyrolysis and its product distribution were studied using a thermogravimetric analyzer and a fixed bed reactor. A gas chromatograph and a gas chromatograph–mass spectrometer were employed to test the properties and composition of the pyrolytic products. Results showed that the pyrolysis temperature of the raw coal ranged mainly from 350 to 650 °C. The weight-loss rate reached a maximum of 6.95%/min at 443 °C. The weight loss was 44.27% at the final pyrolysis temperature of 750 °C. The tar yield of raw coal was 9.51% in the fixed bed reactor at 600 °C. Adding iron ore, which was intended for a lower tar yield and a higher fraction of light tar (boiling point <360 °C), had a catalytic effect on the pyrolysis of raw coal. With separate addition of hematite and specularite, both having a mass of 20% of the raw coal, coal weight loss increased by 3.86% and 5.56%, respectively, when the catalytic upgrading was at 600 °C, and good upgrading effect was obtained. Meanwhile, benzene homologue in tar increased slightly, by 0.62% and 1.44%, compared to that in the tar of the raw coal. The upgrading effects of iron ore on tar also lowered element O content in the resulting tar, by 36.89% with the addition of hematite and by 43.16% with specularite. The iron concentrate recovered was measured by magnetic separation method. The iron concentrate grade was 52.97% with hematite added in coal when the residence time of ultimate pyrolysis temperature was 25 min and the magnetic field strength was 96.48 kA/m, while it was 58.02% with specularite added when the residence time was 35 min and the magnetic field strength was 109.27 kA/m, both with a char grinding fineness of less than 0.074 mm (ground char accounting for approximately 80% of total char); iron concentrate recovery rate was 85.31% and 76.74%, respectively. The experimental results proved the feasibility of recovering iron ore in char by magnetic separation.

Effects of hydrothermal treatment on oxygen functional groups and pyrolysis characteristics of a vitrinite‐rich low rank coal

“…It is reported that the pyrolysis characteristics of coal could be clearly reflected by the kinetic parameters based on temperature region among the maximum reaction rate in the second stage of pyrolysis reaction. Therefore, the pyrolysis temperature range of 370°C to 470°C was used to study the kinetic parameters in this work.…”

Study on the Catalytic Pyrolysis Mechanism of Lignite by Using Extracts as Model Compounds

“…Evidently, the catalytic influence of Fe-based catalyst lead to the rise of EX conversion and reduction of the final temperature. Multiple studies [25][26][27] showed that Fe-based catalysts have the capability of cracking the long-chain aliphatic hydrocarbons and lowering the bond energy, thereby making the pyrolysis reaction occur at lower temperature.…”

The Resources of Oil-rich Coals in China

“…The light tar yield could be improved by coupling of in-situ catalytic cracking and the process of ethane steam reforming on the carbon-based catalyst (Zhao, Li et al 2016). Meanwhile, the methods for increasing tar yield and its quality were supposed such as strengthen the structure of volatiles and the control of composition, design a novel pyrolysis reactor to regulate the pyrolysis of coal particles and the secondary reaction process of volatiles, coordinately control pyrolysis conditions, control the dust content in oil and gas, etc (Yang, Fu et al 2015).…”