Preparation of porous glass-ceramics from coal fly ash and asbestos tailings by high-temperature pore-forming

Our plain-English summary of Preparation of porous glass-ceramics from coal fly ash and asbestos tailings by high-temperature pore-forming, by L. Zeng, H. Sun, T. Peng, et al (Waste Management, 2020).

The study

• Authors: L. Zeng, H. Sun, T. Peng, W. Zheng
• Journal: Waste Management
• Published: 2020;106:184-192
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

This paper presented a new method of preparing porous glass-ceramics by high-temperature pore-forming using coal fly ash and asbestos tailings as raw materials. The effects of the content of asbestos tailings and sintering temperature on the phase composition, microstructure and properties of the porous glass-ceramics had been systematically discussed, furthermore, the pore formation mechanism was also expounded. Compared with T0, porous glass-ceramics from T1, T2 and T3 experienced more violent self-expansion during the sintering process due to the addition of asbestos tailings. The porosity of porous glass-ceramics from T3 was 51%, the bulk density was 1.42 g/cm3, the flexure strength was 19 MPa, the main crystal phase was indialite, along with several secondary phases such as anorthite, enstatite, and forsterite. Due to the high strength, the material was expected to be used as a porous construction material with load-bearing function. This work provided a convenient and promising method for the utilization of coal fly ash and asbestos tailings to prepare porous glass-ceramics without adding foaming agents.

Copyright © 2020 Elsevier Ltd. All rights reserved.

In plain English

This was a laboratory materials study from China. The authors tested whether coal fly ash and asbestos tailings could be made into porous glass-ceramics without adding foaming agents. Asbestos tailings, waste from chrysotile mining and processing, here consisted mainly of chrysotile. Both wastes were heated for one hour (fly ash at 850 degrees C, tailings at 900 degrees C), after which the tailings' main phases were forsterite and enstatite. The heated fly ash was mixed with 10%, 20% or 30% heated tailings, pressed and fired at 1000 to 1220 degrees C; heated fly ash alone served for comparison. More tailings gave higher porosity and lowered the temperature at which the mineral indialite formed. Samples without tailings had higher flexural strength. The 30% mixture reached 51% porosity, a bulk density of 1.42 g/cm3 and a flexural strength of 19 MPa. The authors concluded that the material could serve as a load-bearing construction insulation material and that the method offers a simple, more economic way to use these wastes. The study tested materials only, not people or health effects; the authors stated no limitations.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory materials experiment: preparing and testing porous glass-ceramics made from industrial wastes
• Who was studied: No people were studied. The test materials were coal fly ash from Jiangyou City and asbestos tailings from Shiman (printed as 'Shiman Country'), both in Sichuan Province, China. They were mixed into three formulas (T1, T2, T3), and pure heated fly ash (T0) was used for comparison.
• Exposure: Asbestos tailings consisting mainly of chrysotile, with small amounts of dolomite, brucite and magnetite. The fly ash was heated at 850 degrees C and the tailings at 900 degrees C for 1 hour before use. The heated materials (CFA1 and ASB1) were mixed in weight ratios of 90:10, 80:20 and 70:30 and sintered at 1000 to 1220 degrees C for 60 minutes.
• Main results:
  • After heating at 900 degrees C, the main phases of the asbestos tailings (ASB1) were reported to be forsterite and enstatite.
  • Porosity was higher when more asbestos tailings were added.
  • With 10%, 20% and 30% asbestos tailings, indialite appeared at 1180, 1160 and 1140 degrees C, respectively.
  • Porous glass-ceramics made without asbestos tailings had higher flexural strength than those made with tailings.
  • The T3 samples (30% asbestos tailings) had 51% porosity, a bulk density of 1.42 g/cm3 and a flexure strength of 19 MPa. Across the mixtures with tailings, the article's comparison table gives porosity of 41 to 51%, flexural strength of 19.42 to 23.57 MPa and bulk density of 1.42 to 1.62 g/cm3.
  • In T3 samples, pore size increased from 184 to 367 micrometres to 423 to 767 micrometres as the firing temperature rose from 1180 to 1200 degrees C.
• The authors' conclusion: The authors concluded that porous glass-ceramics with indialite as the main crystal phase can be made from coal fly ash and asbestos tailings without foaming agents. They stated that pore size and porosity can be controlled through firing temperature and the amount of tailings added. They concluded that, because of its high strength, the material can be used as a load-bearing construction insulation material.

Topics

Medical terms in this study, explained in our Lexicon: Tailings, Forsterite.

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