High-temperature transformation of pyrite in CO2: effects of residence time and the presence ofO2

Jianqun Wu; Dunxi Yu; Xin Yu; Fangqi Liu; Sheng Chen; Minghou Xu

doi:10.1016/j.proci.2020.06.264

High-temperature transformation of pyrite in CO₂: effects of residence time and the presence ofO₂

Jianqun Wu, Dunxi Yu^*, Xin Yu, Fangqi Liu, Sheng Chen, Minghou Xu^*

^*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

7 Citations (Scopus)

Abstract

To understand the behavior of pyrite (a key slag-inducing coal mineral) in oxyfuel combustion (O₂/CO₂ combustion), our previous work firstly investigated the effects of pure CO₂ on fixed bed reactors and at low temperatures (<1273 K) and long residence time (order of minutes). As a consecutive contribution, this work explores pyrite transformation in CO₂ with the presence of O₂ on a drop tube furnace (DTF) and at a high temperature of 1573 K. These conditions are more relevant to practical oxyfuel combustion. Pulverized pyrite samples of sizes between 63 and 75 µm were tested in CO₂ with varying O₂ from 0 to 3%, mimicking the conditions near the boiler burners. The changes of pyrite transformation with residence time were investigated by examining the intermediate products, collected by a high-temperature sampling probe. For a clear clarification of the effects of CO₂, tests were also carried out in O₂/N₂ for comparison. The solid products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The gas products were analyzed online by a gas analyzer. Results showed that, in the absence of O₂, CO₂ chemically accelerated pyrite decomposition and oxidation when compared with N₂. This finding was consistent with that in previous work performed on fixed-bed reactors. In the presence of the same O₂ concentration, the positive roles of CO₂ persisted, enhancing the formation of magnetite (Fe₃O₄) and SO₂. In either O₂/CO₂ or O₂/N₂, increasing O₂ concentration also favored the formation of magnetite and SO₂. Significant changes of SO₂ and S in pyrrhotite (FeS_x) were observed between 0.5-0.7 s, and longer residence time did not seem to have significant effects. However, the amount of magnetite formed increased with increasing residence time. The obtained knowledge is new and very useful to further understanding of pyrite behavior in real oxyfuel combustion systems.

Original language	English
Title of host publication	Proceedings of the Combustion Institute
Publisher	Elsevier B.V.
Pages	5493-5500
Number of pages	8
Volume	38
Edition	4
DOIs	https://doi.org/10.1016/j.proci.2020.06.264
Publication status	Published - 2021
Externally published	Yes
Event	38th International Symposium on Combustion - Adelaide Convention Centre, Adelaide, Australia Duration: 24 Jan 2021 → 29 Jan 2021 http://www.combustionsymposia.org/2021/home (Link to conference website)

Publication series

Name
ISSN (Print)	1540-7489

Conference

Conference	38th International Symposium on Combustion
Country/Territory	Australia
City	Adelaide
Period	24/01/21 → 29/01/21
Internet address	http://www.combustionsymposia.org/2021/home (Link to conference website)

Keywords

Oxy-coal combustion
Pyrite transformation
High temperature
Carbon dioxide
Residence time

ASJC Scopus subject areas

General Chemical Engineering
Mechanical Engineering
Physical and Theoretical Chemistry

Documents and Links

10.1016/j.proci.2020.06.264

Cite this

@inproceedings{7ee19b631cce4134a287191933337782,

title = "High-temperature transformation of pyrite in CO2: effects of residence time and the presence ofO2",

abstract = "To understand the behavior of pyrite (a key slag-inducing coal mineral) in oxyfuel combustion (O2/CO2 combustion), our previous work firstly investigated the effects of pure CO2 on fixed bed reactors and at low temperatures (<1273 K) and long residence time (order of minutes). As a consecutive contribution, this work explores pyrite transformation in CO2 with the presence of O2 on a drop tube furnace (DTF) and at a high temperature of 1573 K. These conditions are more relevant to practical oxyfuel combustion. Pulverized pyrite samples of sizes between 63 and 75 µm were tested in CO2 with varying O2 from 0 to 3%, mimicking the conditions near the boiler burners. The changes of pyrite transformation with residence time were investigated by examining the intermediate products, collected by a high-temperature sampling probe. For a clear clarification of the effects of CO2, tests were also carried out in O2/N2 for comparison. The solid products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The gas products were analyzed online by a gas analyzer. Results showed that, in the absence of O2, CO2 chemically accelerated pyrite decomposition and oxidation when compared with N2. This finding was consistent with that in previous work performed on fixed-bed reactors. In the presence of the same O2 concentration, the positive roles of CO2 persisted, enhancing the formation of magnetite (Fe3O4) and SO2. In either O2/CO2 or O2/N2, increasing O2 concentration also favored the formation of magnetite and SO2. Significant changes of SO2 and S in pyrrhotite (FeSx) were observed between 0.5-0.7 s, and longer residence time did not seem to have significant effects. However, the amount of magnetite formed increased with increasing residence time. The obtained knowledge is new and very useful to further understanding of pyrite behavior in real oxyfuel combustion systems.",

keywords = "Oxy-coal combustion, Pyrite transformation, High temperature, Carbon dioxide, Residence time",

author = "Jianqun Wu and Dunxi Yu and Xin Yu and Fangqi Liu and Sheng Chen and Minghou Xu",

year = "2021",

doi = "10.1016/j.proci.2020.06.264",

language = "English",

volume = "38",

publisher = "Elsevier B.V.",

pages = "5493--5500",

booktitle = "Proceedings of the Combustion Institute",

address = "Netherlands",

edition = "4",

note = "38th International Symposium on Combustion ; Conference date: 24-01-2021 Through 29-01-2021",

url = "http://www.combustionsymposia.org/2021/home",

}

Wu, J, Yu, D, Yu, X, Liu, F, Chen, S & Xu, M 2021, High-temperature transformation of pyrite in CO₂: effects of residence time and the presence ofO₂. in Proceedings of the Combustion Institute. 4 edn, vol. 38, Elsevier B.V., pp. 5493-5500, 38th International Symposium on Combustion, Adelaide, South Australia, Australia, 24/01/21. https://doi.org/10.1016/j.proci.2020.06.264

TY - GEN

T1 - High-temperature transformation of pyrite in CO2: effects of residence time and the presence ofO2

AU - Wu, Jianqun

AU - Yu, Dunxi

AU - Yu, Xin

AU - Liu, Fangqi

AU - Chen, Sheng

AU - Xu, Minghou

PY - 2021

Y1 - 2021

N2 - To understand the behavior of pyrite (a key slag-inducing coal mineral) in oxyfuel combustion (O2/CO2 combustion), our previous work firstly investigated the effects of pure CO2 on fixed bed reactors and at low temperatures (<1273 K) and long residence time (order of minutes). As a consecutive contribution, this work explores pyrite transformation in CO2 with the presence of O2 on a drop tube furnace (DTF) and at a high temperature of 1573 K. These conditions are more relevant to practical oxyfuel combustion. Pulverized pyrite samples of sizes between 63 and 75 µm were tested in CO2 with varying O2 from 0 to 3%, mimicking the conditions near the boiler burners. The changes of pyrite transformation with residence time were investigated by examining the intermediate products, collected by a high-temperature sampling probe. For a clear clarification of the effects of CO2, tests were also carried out in O2/N2 for comparison. The solid products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The gas products were analyzed online by a gas analyzer. Results showed that, in the absence of O2, CO2 chemically accelerated pyrite decomposition and oxidation when compared with N2. This finding was consistent with that in previous work performed on fixed-bed reactors. In the presence of the same O2 concentration, the positive roles of CO2 persisted, enhancing the formation of magnetite (Fe3O4) and SO2. In either O2/CO2 or O2/N2, increasing O2 concentration also favored the formation of magnetite and SO2. Significant changes of SO2 and S in pyrrhotite (FeSx) were observed between 0.5-0.7 s, and longer residence time did not seem to have significant effects. However, the amount of magnetite formed increased with increasing residence time. The obtained knowledge is new and very useful to further understanding of pyrite behavior in real oxyfuel combustion systems.

AB - To understand the behavior of pyrite (a key slag-inducing coal mineral) in oxyfuel combustion (O2/CO2 combustion), our previous work firstly investigated the effects of pure CO2 on fixed bed reactors and at low temperatures (<1273 K) and long residence time (order of minutes). As a consecutive contribution, this work explores pyrite transformation in CO2 with the presence of O2 on a drop tube furnace (DTF) and at a high temperature of 1573 K. These conditions are more relevant to practical oxyfuel combustion. Pulverized pyrite samples of sizes between 63 and 75 µm were tested in CO2 with varying O2 from 0 to 3%, mimicking the conditions near the boiler burners. The changes of pyrite transformation with residence time were investigated by examining the intermediate products, collected by a high-temperature sampling probe. For a clear clarification of the effects of CO2, tests were also carried out in O2/N2 for comparison. The solid products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The gas products were analyzed online by a gas analyzer. Results showed that, in the absence of O2, CO2 chemically accelerated pyrite decomposition and oxidation when compared with N2. This finding was consistent with that in previous work performed on fixed-bed reactors. In the presence of the same O2 concentration, the positive roles of CO2 persisted, enhancing the formation of magnetite (Fe3O4) and SO2. In either O2/CO2 or O2/N2, increasing O2 concentration also favored the formation of magnetite and SO2. Significant changes of SO2 and S in pyrrhotite (FeSx) were observed between 0.5-0.7 s, and longer residence time did not seem to have significant effects. However, the amount of magnetite formed increased with increasing residence time. The obtained knowledge is new and very useful to further understanding of pyrite behavior in real oxyfuel combustion systems.

KW - Oxy-coal combustion

KW - Pyrite transformation

KW - High temperature

KW - Carbon dioxide

KW - Residence time

U2 - 10.1016/j.proci.2020.06.264

DO - 10.1016/j.proci.2020.06.264

M3 - Conference contribution

AN - SCOPUS:85090459900

VL - 38

SP - 5493

EP - 5500

BT - Proceedings of the Combustion Institute

PB - Elsevier B.V.

T2 - 38th International Symposium on Combustion

Y2 - 24 January 2021 through 29 January 2021

ER -