This study proposed an evaluation of enrichment processes of obsolete Printed Circuit Boards (PCBs), by means of gravity and electrostatic separation, aiming at the recovery of metals. PCBs are the most important component in electronic devices, having high concentrations of metals and offering a secondary source of raw materials. Its recycling promotes the reduction in the environmental impacts associated with its production, use, and disposal. The recovery method studied started with the dismantling of the PCB, followed by a comminution and granulometric classification. Subsequent magnetic, gravity, and electrostatic separations were performed. After the separations, a macroscopic visual evaluation and chemical analysis were carried out, determining the metal content in the concentrate products. The results obtained from gravity separation showed a product with metallic concentrations of 89% and 76% for particle sizes of 0.3–0.6 mm and 0.6–1.18 mm, respectively. In electrostatic separation, the product obtained was 88% for the lower particle size (1.18 mm.

Vinyl floors are widely used in public areas for their low cost and easy cleaning. From 1960 to 1980, asbestos was often added to improve vinyl floor performances. The Italian Ministerial Decree (M.D.) 06/09/94 indicates asbestos vinyl tiles as non-friable materials and, therefore, few dangerous to human health. This work aims to check through three different experimental tests if asbestos floor tiles, after decades of use, maintain their characteristics of compactness and non-friability. The effect of a small stone fragment stuck in the sole of rubber shoes was reproduced by striking the vinyl floor with a crampon. A vinyl tile was broken into smaller pieces with the aid of pliers to simulate what normally happens when workers replace the floors or sample it to verify the presence of asbestos. The third test reproduced the abrasion of the tile surface due to the dragging of furniture or heavy materials or sand grains that remain attached to the soles of shoes. The tests were carried out in safe conditions, working under an extractor hood with a glove box. Airborne sampling in the hood obtained the concentration of asbestos fibers produced in each test. The simulation tests performed confirms the possible release of fibers if the vinyl tiles are cut, abraded or perforated, as indicated by the Italian M.D.

The problem of acid gas exhaust emissions treatment has not been fully resolved at present. Dry adsorption of acid gases with alkaline sorbents is currently being investigated, to improve solid sorbents. In this study, 5 types of hydrated lime were characterised and tested. The sorption capacities were measured by means of a system consisting of a feed line (HCl/N₂), a thermostatic reactor and a water absorber. The physical characteristics of sorbent samples were also compared. Analyses conducted with scanning electronic microscopy revealed that sample C1 showed uniform particle distribution. Samples C2 and C3 showed the co-presence of fine and coarse particles. Sample C4 showed very fine particles with agglomeration phenomena. In sample C5, fibrous elements were found. Energy dispersive spectrometry (EDS) analyses showed a similar composition of the samples, with the exception of the presence of Mg in some of them. After 30 min of testing, the following differences in sorption capacities with respect to C1 (3.59 mg g⁻¹) were found: C2, −20%; C3, −13%; C4, −17%; C5, −3%. Higher sorption capacities were associated with more uniform particle size distributions. Conversely, agglomeration of fine particles may have adversely affected the performance of sorbents.

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.

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.