Change of carcinogenic chrysotile fibers in the asbestos cement (eternit) to harmless waste by artificial carbonatization: petrological and technological results

Our plain-English summary of Change of carcinogenic chrysotile fibers in the asbestos cement (eternit) to harmless waste by artificial carbonatization: petrological and technological results, by M. Radvanec, L. Tuček, J. Derco, et al (Journal of Hazardous Materials, 2013).

The study

• Authors: M. Radvanec, L. Tuček, J. Derco, K. Čechovská, Z. Németh
• Journal: Journal of Hazardous Materials
• Published: 2013;252-253:390-400
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos cement materials, mainly the eternit roof ceiling, being widely applied in the past, represent a serious environmental load. The solar radiation, rain and frost cause the deliberation of cement from the eternit roofing and consequently the wind contaminates the surrounding area by the asbestos (chrysotile) fibers. In combination with other carcinogens (e.g. smoking), or at reduced immunity of a man, they may cause serious respiratory diseases and lung cancer. The article presents the procedure and experimental results of artificial carbonatization, applied in the asbestos cement (eternit). The wet crushed and pulverized asbestos cement was thermally modified at 650°C and then the chrysotile fibers easily and completely reacted with the mixture of CO2 and water, producing new Mg-rich carbonates - hydromagnesite and magnesite: [Formula: see text] Applying this methodology, the asbestos-bearing waste can be stabilized and environmentally friendly permanently deposited. Finding a way of neutralizing of extreme pH values (around 12) at large eternit dumps represents also an asset of presented research. Simultaneously, the artificial carbonatization of chrysotile asbestos, applying CO2, offers an alternative way for permanent liquidation of a part of industrial CO2 emissions, contributing to multiple benefit of this methodology.

Copyright © 2013 Elsevier B.V. All rights reserved.

In plain English

This was a laboratory experiment, not a study of people. The authors tested whether chrysotile asbestos in asbestos cement roofing (eternit) could be converted into carbonate minerals using carbon dioxide and water. They ground a 10 kg roofing sample in which chrysotile made up 11.7% by volume. Half was used as it was, and half was first heated for 1 hour at 650 degrees Celsius. Both were then reacted with carbon dioxide and water at 22 degrees Celsius. In the unheated material, the chrysotile fibers did not react. In the heated material, the major part of the chrysotile reacted and formed the magnesium carbonates magnesite and hydromagnesite. One figure caption says the fibers in the heated, treated sample were eliminated, but another caption for the same sample lists non-reacted chrysotile. In the unheated test the liquid's pH fell from about 12 to 8. The authors concluded that the method is an effective way to turn chrysotile fibers into stable, harmless carbonates, with best conditions of 22 degrees Celsius, 5 MPa pressure and 1 hour.

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 experiment (mineral chemistry). A ground asbestos cement sample was split into an unheated half and a half heated for 1 hour at 650 degrees Celsius. Both halves were reacted with carbon dioxide and water in a high-pressure reactor at 22 degrees Celsius, at pressures of 2.5, 5.0 and 7.5 MPa and for different times. The products were then examined by microscopy, chemical analysis, X-ray diffraction and microprobe.
• Who was studied: One 10 kg sample of asbestos cement (eternit) roofing, processed and analyzed at the State Geological Institute in Slovakia. The article does not say where the roofing came from or when the experiments were done. No people were studied.
• Exposure: Chrysotile asbestos, which made up 11.7% by volume of the ground roofing material (Table 1 lists mineral components in vol.%), treated with carbon dioxide and water, with or without prior heating at 650 degrees Celsius.
• Main results:
  • In the unheated sample, the chrysotile fibers did not react with water and carbon dioxide and remained stable.
  • In the unheated sample, the calcium carbonates that formed came from the cement minerals, while the magnesium bound in chrysotile stayed unchanged.
  • For the unheated sample at 22 degrees Celsius, 1 hour and 5 MPa, the liquid after the reaction had a pH of 8. Before the reaction, the suspension had a pH of around 12.
  • In the heated sample, the major part of the chrysotile reacted with water and carbon dioxide and passed into a slurry, from which magnesite and hydromagnesite crystallized.
  • A figure caption for the filtered solid from the heated sample (EZ5) states that the chrysotile fibers were eliminated. A different figure caption describes non-reacted chrysotile in that same sample.
  • The products settled out of the liquids from the heated sample were mainly hydromagnesite and aragonite. Together these made up 69.6% (sample EZ15) to 82.0% (sample EZ6) of those products.
  • For the heated sample at 22 degrees Celsius, 5 MPa and 1 hour, the weight of settled-out product rose by 5.66%, with 82.0% magnesium plus calcium carbonates.
  • In the heated sample's products, the carbon dioxide bound ranged from 13.5% (EZ15) to 17.7% (EZ6).
• The authors' conclusion: The authors concluded that artificial carbonatization of asbestos cement is an effective way to eliminate chrysotile asbestos fibers by changing them into stable and harmless carbonates. Heating first at 650 degrees Celsius helped the reaction, and the best conditions were 22 degrees Celsius, 5 MPa and 1 hour. They also suggested the method could permanently store part of industrial carbon dioxide emissions.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Carcinogenic, Chrysotile, Asbestos-Cement, Eternit, Lung Cancer.

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