The main objective of this work is the evaluation of the morphology change in tremolite particles before and after a grinding process. The crushing action simulates anthropic alteration of the rock, such as excavation in rocks containing tremolite during a tunneling operation. The crystallization habit of these amphibolic minerals can exert hazardous effects on humans. The investigated amphibolic minerals are four tremolite samples, from the Piedmont and Aosta Valley regions, with different crystallization habits. The habits can be described as asbestiform (fibrous) for longer and thinner fibers and non-asbestiform (prismatic) for prismatic fragments, also known as “cleavage” fragments. In order to identify the morphological variation before and after the grinding, both a phase contrast optical microscope (PCOM) and a scanning electron microscope (SEM) were used. The identification procedure for fibrous and prismatic elements is related to a dimensional parameter (length–diameter ratio) defined by the Health and Safety Executive. The results highlight how mineral comminution leads to a rise of prismatic fragments and, therefore, to a potentially safer situation for worker and inhabitants.

Every mining operation is followed by a beneficiation process aimed at delivering quality materials to the transformation industry. Mainly, in order to separate valuable minerals from gangue in mineral processing, the crushing and grinding of extracted ore are crucial operations for the following separation steps. Comminution is the most energy-consuming operation in mining, and the quality of the results is strictly related to the characteristic of the material under treatment, the type of equipment used in comminution, and the circuit design adopted. A preliminary study was performed in order to understand the crushing behavior under different comminution forces of a high-grade mixed Zn-Pb sulfide ore sample, collected in a Mississippi-Valley Type (MVT) deposit, and the distribution of the target minerals among the products of the process. Ore samples were examined and characterized through thin section observation and SEM analyses for the determination of grain size and texture features, while X-ray powder diffraction (XRPD) quantitative analyses were performed for the definition of target mineral concentrations of comminuted product samples. The selected crushing and grinding circuit comprised lab-scale equipment. For each stage of the process, products below the estimated free-grain size threshold were collected, and particle size analyses were carried out. Comminution products were divided into size distribution classes suitable for further separation operations, and XRPD analyses showed a mineral-grade distribution varying with the dimensions of the products. Characterization of the ore material after crushing and grinding force applications in terms of the distribution of target minerals among different-sized classes was achieved. The important trends highlighted should be considered for further investigation related to an efficient separation.

The presence of Naturally Occurring Asbestos (NOA) is one of the greatest danger during excavations and tunneling.  The most important instrument for the NOA content prediction is the geological model.As part of the consultancy provided in the works of the "Terzo valico dei Giovi" which includes the excavation of numerous tunnels in areas potentially affected by rocks containing asbestos, the case study of the tunnel called "Castagnola" is illustrated. The opera is the new high velocity railway connection between Genova and Milano and the case study is located in the Piedmont southern area near Fraconalto (AL).The “Castagnola” tunnel area is characterized by greenish - reddish rocks metabasalt covered by recent grey shales in the upper part of the area; it refers to the ophiolitic Figogna Unit, elongated in a north-south direction, which belongs to Sestri-Voltaggio Zone.Starting from geological sections and thanks to surface investigation and core drilling, an effective geological model was built.This study highlights how, during the progress of the works, situations other than the forecast geological model are encountered. It also highlights the importance of the environmental monitoring of the airborne fibers dispersion inside the tunnel, which has proved extremely effective even in the presence of low asbestos content in the excavated rock.Moreover, this study describes the trends in asbestos content in the material excavated during the route of the tunnel in comparison with the concentration of airborne fibers. Furthermore, the management of the asbestos problem, from the abatement of dust to the excavation and storage methods and the installation of efficient technologies such as an aspirating ventilation system already successfully tested in a previous excavation phase, are presented.

The main morphological characteristic, related to the dangerousness of the six minerals defined as asbestos, is the crystallization of the mineral itself with a fibrous habit.In different geological conditions these minerals can crystallize even with different morphological aspect. The fibrousness of the mineral is fundamental to define its carcinogenicity because, when these fibres are inhaled, they can cause serious diseases.Different studies has already showed that the grinding of fibrous minerals can showed a decrease in dehydroxylation and breakdown temperatures due to the increase in lattice strain and the decrease in crystallinity.In this study the answer to the grinding of different Tremolite with different crystal habit are studied. Tremolite, which is classified as carcinogenic substances group 1 by the IARC, is a hydrated calciummagnesium silicate (Ca2Mg5Si8O22(OH)2), belonging to the tremolite-ferro-actinolite series, that can crystallize with two different habits: fibrous, known as asbestiform, or prismatic, known as non-asbestiform.This decision arises from the need to verify if the tremolite with prismatic habit, if subjected to a grinding process, can produce potentially harmful fibers. 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).Following the definition of fiber from the Health and Safety Executive, a dimensional analysis, based on a direct measurement of the particle size (length and diameter), has been carried out. The results of this research indicate that the prevalent morphology of an amphibolic mineral can change habit. Moreover, the production of prismatic components in an amphibolic mineral by means of grinding action (digging or earthmoving), can generally be a safer situation for the exposed subjects, such as workers and inhabitants.

As the main responsible of pollution, particulate matter (PM) in big cities and industrial sites greatly affects the life quality of an ever-growing number of people all over the world. That situation drives the strong effort for continuous PM monitoring by governmental and environmental protection agencies. Despite great attention to such air quality control, the analysis of particulate is often limited to the study of size distribution and elemental composition giving only few information on the pollutant sources of origin (source apportionment). Information about such sources could assist in the development of strategies towards the reduction of pollutant emissions.In this framework, we report a novel integrated approach for the qualitative and quantitative analysis of air particulate. The developed method leverages on the integration of different analytical techniques on PM samples such as Scanning Electron Microscopy (SEM), Raman Spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). The proposed protocol aims both at identifying the main constituents of air particulate identifying at the same time its sources (car wheel, combustion, asphalt, car brake, etc…).The SEM analysis provides information on the size distribution and elemental composition of the particles, whereas the Raman and FTIR spectroscopy allow for the identification of the actual components. By comparing the results of the analysis with a database of spectra obtained from known samples, PM particles can be associated with a probable source.Finally, a mapping strategy of air sampling filters for the rough quantification of each component of the particulate via Raman and FTIR spectroscopy will be presented.