The mechanism of decomposition of serpentines from peridotites on heating

Study on the thermal decomposition of crocidolite asbestos

“…Thermal decomposition of chrysotile asbestos is fairly well understood and has been described in the technical literature [11][12][13][14][15][16][17][18][19][20][21][22][23][24]. A summary of the thermal transformations of chrysotile asbestos, which was approximately 90 % of world production, is represented by the following reaction path [25]:…”

Kinetics study on the dehydroxylation and phase transformation of Mg3Si2O5(OH)4

“…Forsterite diffraction peaks can be observed only at T > 948 K. These findings indicate that the lizardite in the investigated sample decomposed completely at approximately 948 K, corresponding to the formation of forsterite. In addition, the intensity of the forsterite diffraction peaks increased with increasing temperature to 1273 K; the appearance of enstatite occurred with a weak diffraction peak after the formation of forsterite, when lizardite was completely decomposed at T > 1073 K. Therefore, sharp exothermic peaks with maximum of approximately 1094 K on the DSC curves indicate overlapping processes of forsterite enlargement and recrystallization [25]. As the temperature increased to 1473 K, the diffraction peaks of enstatite were significantly enhanced, accompanied by weakening of the forsterite diffraction peaks.…”

“…Many previous investigations on the thermal behaviour of serpentine minerals have mainly focused on chrysotile and/or antigorite minerals [5e18], whereas studies on the thermal behaviour of lizardite are rare [19e24]. Some scholars have only used thermogravimetric (TG) and/or differential thermogravimetric (DTG) data to investigate the kinetics of serpentine transformation behaviour [17,25,26]. However, differential scanning calorimetry (DSC) data obtained in this study has shown a broad endothermic peak at~898 K, corresponding to dehydroxylation, and a sharp exothermic peak at~1094 K, related to the phase transformation.…”

Obtaining an Artificial Aggregate from Cement-Asbestos Waste by the Melting Technique in an Arc-Resistance Furnace

“…Another phenomenon in this range of temperatures, which seems important from the point of view of this work, is also the dehydroxylation of minerals, like chrysotile (white asbestos) and lizardite, combined with their thermal decomposition and the formation of new mineral phases. The thermal decomposition of these minerals with the formation of new mineral phases, like forsterite (Mg 2 SiO 4 ) and/or enstatite (MgSiO 3 ), was thoroughly studied in the past few years [30,32,63]. The above transformations could be simplified and represented by the following overall reaction: Mg 3 (OH) 4 Si 2 O 5 → Mg 2 SiO 4 + MgSiO 3 + 2H 2 O, which allows for the thermal transformation of asbestos fibers into new minerals, characterized by complete recrystallization.…”