Thermal behavior of tremolite: a new method for distinguishing between asbestos and non-asbestos tremolite samples
Authors: Bloise Andrea 
Published: February 2023

&lt;p&gt;In the past, studies on the thermal behaviour of tremolite focused mainly on understanding its crystal chemistry. There has recently been renewed interest in such studies in view of the possible inertization and/or reuse of tremolite asbestos through thermally-induced crystal-chemical transformation. The tremolite breakdown temperature reported in the literature varies by about 280 &amp;#176;C (Bloise et al., 2017). What is the reason for this broad range of tremolite breakdown temperatures? Are there differences in sample preparation or in experimental conditions during thermogram acquisition, or do variations reflect intrinsic differences among samples (e.g., chemistry, morphology)? To answer these questions, thermogravimetric and differential scanning calorimetry (TG/DSC) were used to study the thermal behaviour of twelve tremolite samples selected from different locations: San Severino Lucano, Basilicata region, southern Italy; Val Malenco, Lombardy region, northern Italy; Montgomery County, Maryland, USA; Praborna, Aosta Valley region, northern Italy; Monastero di Lanzo, Piedmont region, northern Italy; Val d&amp;#8217;Ala, Piedmont region, northern Italy; Reventino, Calabria region, southern Italy; Verrayes, Aosta Valley region, northern Italy; Bracchiello, Piedmont region, northern Italy; Caprie, Piedmont region, northern Italy; Fowler, St. Lawrence Co., New York, USA; Campolungo, Ticino Alps, Switzerland. PXRD, EPMA/SEM/TEM/EDS were used to characterize tremolite samples before heating to 1200 &amp;#176;C; the same samples were analysed by PXRD after heat treatment up to 1200 &amp;#176;C. Thermal analysis of the above-mentioned tremolite samples yielded breakdown temperatures ranging from 997 to 1182 &amp;#176;C. These temperatures were compared and discussed in light of chemical, mineralogical and morphological data. Variations in the breakdown temperature are mainly ascribed to the morphology of the studied tremolite samples. This study suggests that thermal analysis could be a new method for effectively distinguishing between asbestos and non-asbestos tremolite samples. Given the different temperatures recorded for tremolite breakdown, the effectively detecting the presence of tremolite in bulk samples by thermal analysis can only be carried out if a thermogram of that specific sample is available. This is an important issue, especially in areas with naturally-occurring asbestos tremolite outcrops and where asbestos tremolite were used for manufacturing various commercial products. Moreover, given its very wide thermal breakdown interval, the thermal behaviour of tremolite should be carefully assessed before the inertization of tremolite asbestos materials; this enables the selection of appropriate temperatures for breakdown while optimizing energy consumption and treatment costs. Another aspect that emerges from this research is that the Fe content does not significantly affect the tremolite breakdown temperature. However, the thermal oxidation of iron, considered responsible for fibre toxicity (Pacella et al., 2020), occurs at different temperatures. Suppression of tremolite reactivity through the thermal oxidation of iron should therefore be planned on a sample-by-sample basis. &amp;#160;&lt;/p&gt;
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&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;
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&lt;p&gt;Bloise A., Kusiorowski R., Lassinantti Gualtieri M., Gualtieri A.F. 2017. Thermal behaviour of mineral fibres. In: A.F. Gualtieri (Ed.) &amp;#8220;Mineral fibres: crystal chemistry, chemical&amp;#8211;physical properties, biological interaction and toxicity&amp;#8221;. European Mineralogical Union, London, pp. 215-252.&lt;/p&gt;
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&lt;p&gt;Pacella A., Tomatis M., Viti C., Bloise A., Arrizza L., Ballirano P., Turci F. 2020. Thermal inertization of amphibole asbestos modulates Fe topochemistry and surface reactivity.&amp;#160;J.&amp;#160;Hazard.&amp;#160;Mater.&amp;#160;398, 123119.&lt;/p&gt;
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