Chemical elimination of the harmful properties of asbestos from military facilities

Our plain-English summary of Chemical elimination of the harmful properties of asbestos from military facilities, by A. Pawełczyk, F. Božek, K. Grabas, et al (Waste Management, 2017).

The study

• Authors: A. Pawełczyk, F. Božek, K. Grabas, J. Chęcmanowski
• Journal: Waste Management
• Published: 2017;61:377-385
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

This work presents research on the neutralization of asbestos banned from military use and its conversion to usable products. The studies showed that asbestos can be decomposed by the use of phosphoric acid. The process proved very effective when the phosphoric acid concentration was 30%, the temperature was 90°C and the reaction time 60min. Contrary to the common asbestos treatment method that consists of landfilling, the proposed process ensures elimination of the harmful properties of this waste material and its transformation into inert substances. The obtained products include calcium phosphate, magnesium phosphate and silica. Chemical, microscopic and X-ray analyses proved that the products are free of harmful fibers and can be, in particular, utilized for fertilizers production. The obtained results may contribute to development of an asbestos utilization technique that fits well into the European waste policy, regulated by the EU waste management law.

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In plain English

In this laboratory chemistry study, not a study of people's health, the authors tested whether phosphoric acid could break down military asbestos waste. They used sealing cord from retired combat infantry vehicles and asbestos-cement (eternit) board from demolished military storage buildings, collected from an army unit in south Poland. X-ray analysis found chrysotile, antigorite and lizardite in the cord, and actinolite and chrysotile in the board. Ground 50.0 g samples were treated at 90 degrees C for 60 minutes with phosphoric acid at 30% expressed as P2O5. The leftover solid weighed 15.6 g for the cord and 9.4 g for the board. It still contained elongated structures, so a second treatment with a 20% acid surplus was added. After that second stage, optical microscope counts detected no fibers in either material after 60 minutes at 30% acid. X-ray peaks for chrysotile disappeared from the cord product. The authors concluded that phosphoric acid may be used for neutralization, though two-stage treatment may be necessary. They suggested the reaction liquid, after neutralization with lime, could be processed into fertilizer. They said further studies may be necessary to exclude doubts about product safety.

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 on chemical (phosphoric acid) treatment of asbestos waste, with chemical, microscopic and X-ray analysis of the materials before and after treatment
• Who was studied: Asbestos waste materials, not people: asbestos sealing cord from combat infantry vehicles withdrawn from the army, and asbestos-cement (eternit) board from demolished military storage facilities, collected from an army unit in south Poland
• Exposure: Treatment of ground 50 g waste samples with raw industrial phosphoric acid. First stage: 30% acid (in terms of P2O5), 90 degrees C, 60 min. Second stage: 30% acid at 90 degrees C for up to 120 min with a 20% acid surplus. Different acid concentrations (10 to 30% in terms of P2O5) and times (10 to 120 min) were compared in the second stage.
• Main results:
  • X-ray analysis of the starting asbestos cord identified the serpentine minerals chrysotile, antigorite and lizardite
  • X-ray analysis of the starting asbestos-cement board showed actinolite (chrysotile was also identified)
  • After single-stage treatment, the 50.0 g asbestos cord sample was reduced to 15.6 g of solid; the flat asbestos-cement sample was reduced to 9.4 g
  • After single-stage treatment, magnesium passed almost entirely into the liquid
  • After single-stage treatment, elongated structures remained in the solid residues, especially from the asbestos cord. The authors stated that the first-stage conditions were not sufficient to completely destroy the asbestos structures.
  • Semi-qualitative optical microscope fiber counts were made after the second-stage treatment at 90 degrees C with a 20% acid surplus. Fibers decreased with longer time and higher acid concentration. At 30% acid (in terms of P2O5), no fibers were detected at 60 min for either material. At 10% acid, fibers were not detected until 90 min.
  • X-ray peaks specific for chrysotile disappeared in the asbestos cord product after the second stage, and new phases including silica were formed
  • The asbestos-cement board product after the second stage contained mainly silica and gypsum
• The authors' conclusion: The authors concluded that phosphoric acid may be used to neutralize this asbestos waste, but that two-stage treatment may be necessary. They suggested that the reaction liquid may be used, after neutralization with lime, for further processing into fertilizer products.
• Limitations the authors state:
  • The authors stated that further studies may be necessary to exclude any doubts related to the safety of the products

Related studies

• Change of carcinogenic chrysotile fibers in the asbestos cement (eternit) to harmless waste by artificial carbonatization: petrological and technological results — M. Radvanec, L. Tuček, et al. (2013)
• Morphological changes during enhanced carbonation of asbestos containing material and its comparison to magnesium silicate minerals — G. Gadikota, C. Natali, et al. (2014)
• Thermochemical destruction of asbestos-containing roofing slate and the feasibility of using recycled waste sulfuric acid — S.N. Nam, S. Jeong, et al. (2014)
• Crystal chemistry of the high temperature product of transformation of cement-asbestos — A. Viani, A.F. Gualtieri, et al. (2013)
• How are the physical and chemical properties of chrysotile asbestos altered by a 10-year residence in water and up to 5 days in simulated stomach acid? — K. Seshan (1983)
• Dangerous and cancer-causing properties of products and chemicals in the oil-refining and petrochemical industries. Part IX: Asbestos exposure and analysis of exposures — M.A. Mehlman (1991)

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