Abstract
The six commercial asbestos minerals (chrysotile, fibrous actinolite, crocidolite, amosite, fibrous tremolite, and fibrous anthophyllite) are classified by the IARC as carcinogenic to humans. There are currently several lines of research dealing with the inertisation of asbestos minerals among which the dry grinding process has received considerable interest. The effects of dry grinding on tremolite asbestos and anthophyllite asbestos in eccentric vibration mills have not yet been investigated. Along the research line of the mechanical treatment of asbestos, the aim of this study was to evaluate the effects of dry grinding in eccentric vibration mills on the structure, temperature stability, and fibre dimensions of tremolite asbestos from Val d’Ala, (Italy) and UICC standard anthophyllite asbestos from Paakkila mine (Finland) by varying the grinding time (30 s, 5 min, and 10 min). After grinding for 30 s to 10 min, tremolite asbestos and anthophyllite asbestos showed a decrease in dehydroxylation and breakdown temperatures due to the increase in lattice strain and the decrease in crystallinity. Moreover, after grinding up to 10 min, tremolite and anthophyllite fibres were all below the limits defining a countable fibre according to WHO.
Highlights
Tremolite Ca2 Mg5 Si8 O22 (OH)2 asbestos and anthophyllite Mg7 Si8 O22 (OH)2 asbestos are classified as carcinogenic substances group 1 by the IARC [1]
The aim of this study is to evaluate for the first time the effects that dry grinding process for different time in eccentric vibration mills has influence on tremolite and anthophyllite asbestos in terms of their degree of crystallinity, temperature stability, and fibre size
The reduction of the diffraction peak intensity and the decrease of the breakdown temperatures in the Derivative thermogravimetry (DTG)/derivative differential scanning calorimetry (DDSC) curves indicate that the structure of both fibrous tremolite and anthophyllite are rapidly damaged by mechanical treatment even after 5 min grinding
Summary
Tremolite Ca2 Mg5 Si8 O22 (OH) asbestos and anthophyllite Mg7 Si8 O22 (OH) asbestos are classified as carcinogenic substances group 1 by the IARC [1]. The mining and use of tremolite asbestos and anthophyllite asbestos were reduced compared to more commercially available types of asbestos such as chrysotile, crocidolite, and amosite [19,20,21]. Despite their relatively limited use, tremolite asbestos and anthophyllite asbestos have been used in many commercial products such as cements, wall plasters, roofing materials, laboratory materials, in battery boxes, and as fillers in rubber etc. According to the existing regulations, tremolite asbestos and anthophyllite asbestos are banned worldwide [21].
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