TY - JOUR

T1 - One-step microwave preparation of phosphoric acid activated foams from spontaneous combustion coal gangue

AU - Lazorenko, Georgy

AU - Kasprzhitskii, Anton

AU - Chaudhary, Sandeep

N1 - Fabrication and performance characterization of coal gangue-based alkali-activated foams was funded by the Ministry of Science and Higher Education of the Russian Federation, Russia (Agreement No. 075-15-2022-1111). Characterization of raw materials was supported by the Russian Science Foundation, Russia (Grant No. 24-79-10320, https://rscf.ru/en/project/24-79-10320/).

PY - 2025/6/7

Y1 - 2025/6/7

N2 - In this work, the phosphoric acid activated foams from spontaneous combustion coal gangue were successfully fabricated using a simple and fast one-step microwave-assisted method. The physico-mechanical, thermal insulation properties, and microstructure of foam specimens prepared with varying molar concentrations of the activating solution (10–14 M), liquid-to-solid (L/S) ratios (0.425–0.525), microwave power (600–1000 W), microwave irradiation time (7.5–12.5 min), and post-curing temperatures (25–115 °C) were investigated. X-ray microfocus computed tomography (micro CT) and scanning electron microscopy (SEM) results showed that the homogeneous porous structure of the foam specimens was developed at higher H3PO4 concentrations when using 1000 W power of the microwave oven for 10 min. The optimized phosphoric acid-activated foams from spontaneous combustion CG exhibit a thermal conductivity of 0.133 W/mK and an unconfined compressive strength of 10.2 MPa, making them comparable to or better than traditional foam materials derived from CG. The obtained results contribute to further advancing the application of phosphoric acid activated CG foams in the fields of building thermal insulation and other lightweight high-temperature insulating materials.

AB - In this work, the phosphoric acid activated foams from spontaneous combustion coal gangue were successfully fabricated using a simple and fast one-step microwave-assisted method. The physico-mechanical, thermal insulation properties, and microstructure of foam specimens prepared with varying molar concentrations of the activating solution (10–14 M), liquid-to-solid (L/S) ratios (0.425–0.525), microwave power (600–1000 W), microwave irradiation time (7.5–12.5 min), and post-curing temperatures (25–115 °C) were investigated. X-ray microfocus computed tomography (micro CT) and scanning electron microscopy (SEM) results showed that the homogeneous porous structure of the foam specimens was developed at higher H3PO4 concentrations when using 1000 W power of the microwave oven for 10 min. The optimized phosphoric acid-activated foams from spontaneous combustion CG exhibit a thermal conductivity of 0.133 W/mK and an unconfined compressive strength of 10.2 MPa, making them comparable to or better than traditional foam materials derived from CG. The obtained results contribute to further advancing the application of phosphoric acid activated CG foams in the fields of building thermal insulation and other lightweight high-temperature insulating materials.

KW - Acid-activation

KW - Coal gangue

KW - Geopolymer

KW - Microwave foaming

KW - Phosphoric acid

UR - https://www.mendeley.com/catalogue/1d59c708-0bd5-3b0d-a5d2-42de77ea3507/

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-105008572872&origin=inward&txGid=1a67620496e5edbbb00e32e838b32bd2

U2 - 10.1016/j.jiec.2025.06.013

DO - 10.1016/j.jiec.2025.06.013

M3 - Article

JO - Journal of Industrial and Engineering Chemistry

JF - Journal of Industrial and Engineering Chemistry

SN - 1226-086X

ER -