Determination of the concentration of asbestos minerals in highly contaminated mine tailings: An example from abandoned mine waste of Cretaz and Emarese (Valle d'Aosta, Italy)

Abstract

For the first time, this work reports concentration maps of asbestos minerals in contaminated mine tailings drawn using the results of Rietveld quantitative phase analysis (QPA). The investigated sites are located in the Valle d’Aosta region (Italy): Crètaz, the most important Italian magnetite mine, active until 1979 and Emarèse, one the most important chrysotile asbestos mines in Italy, active until 1968. The results of the study permit to draw the spatial distribution of the asbestos (chrysotile and tremolite in this specific case) concentration, useful to plan reclamation of the sites, with priority given to the areas with the highest asbestos concentration. Because of the complexity of the mineral assemblage, which includes, among the others, antigorite, chlorite, talc, and tremolite, the concentration of chrysotile was cross-checked using different experimental techniques such as X-ray powder diffraction (XRPD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), polarized light optical microscopy (PCOM), and differential thermal analysis (DTA). The accuracy of the results was validated by analyzing standard samples with known concentrations of chrysotile and tremolite. The comparison allowed to point out the advantages and disadvantages of each experimental method.\ud \ud At Crètaz, chrysotile ranges from 4.4 to 22.8 wt% and tremolite from 1.0 to 10.3 wt%, whereas at Emarèse the concentration of chrysotile varies from 3.3 to 39.5 wt% and tremolite from 5.9 to 12.4 wt%. Antigorite and chlorite are the major accompanying phases with variable amounts of other accessory minerals including magnetite, carbonates, talc, olivine, pyroxene, talc, and brucite. The results of our study are of key importance for the local environmental policies as the knowledge of the spatial distribution of the asbestos concentration allows to plan a detailed reclamation agenda of the contaminated sites. The spots with the highest surface contamination of both chrysotile and tremolite were identified and classified as priority areas in the reclamation plan

Multi-Analytical Approach for Identifying Asbestos Minerals In Situ

“…These p-XRF data could be used to make a sampling plan aimed at identifying hotspot areas of heavy metal contamination such as the asbestos quarries/mines in Italy, Canada, India, and Argentina [20,41,[57][58][59]. Collected Raman spectra as p-XRF spectra, were conducted exclusively on fibrous morphologies observed inside the serpentinite veins (Figure 3a) using Raman microscope and p-DM.…”

“…In recent years several studies have focused on NOA with the aim of determining the potential health risks for neighboring populations [19][20][21][22][23]. This is due to the relatively widespread presence of NOA that are currently being excavated for numerous construction projects (railway lines, motorways etc.).…”

Grinding Test on Tremolite with Fibrous and Prismatic Habit

“…These events can happen during natural degradation processes of rocks (weathering of outcrops) or during anthropic intervention, such as the mechanized excavation or earthmoving process (transport). These processes, which employ a series of crushing and abrasive actions on the rock, are the cause of dimensional reduction of asbestos fibers, where present, and therefore can provoke serious human health problems linked to the release of fibers in air or in groundwater, so entering in the hydrological system [23].…”

“…x FOR PEER REVIEW 13 of Amounts of fibrous and prismatic component according to the Health and Safety Executive (HSE)[23] before and after grinding.…”

Naturally Occurring Asbestos (NOA) in Granitoid Rocks, A Case Study from Sardinia (Italy)

“…Natural processes (erosion and transport) as well as anthropic activities (mining, crushing, grinding and milling), thus represent an important source of asbestos. Both processes may induce a strong environmental hazard [2,3,11] that can be quantified as a function of the concentration of dispersed fiber in air and in soil/water e.g., [12][13][14][15][16][17][18]. Up to the present, only a limited number of studies from a relatively restricted number of sites have focused on the risk produced by asbestos minerals in their natural settings [1][2][3].…”