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The acceleration of the global production and consumption of electronic devices and the concerns related to waste electrical and electronic equipment (WEEE) motivated this research. Printed circuit boards (PCB) can be found in almost all types of electronic devices, and their composition contains heavy metals that can cause environmental impacts due to improper disposal. However, on the other hand, there are elements with added value, such as copper, gold, silver, iron, aluminum and other critical raw materials, such as tantalum, that can be recovered. Metal recovery can conserve natural resources since it prevents new minerals from being extracted, being a great contribution to the circular economy. In this research, the PCB element composition was initially determined through the scanning electron microscope analysis. Then, the PCB was shredded in a cutting mill and classified in grain size classes by sieving. Afterwards, magnetic separation has been performed together with gravity and electrostatic separation of the non-magnetic fraction. In gravity separation, the metal recovery was satisfactory for the particle size −0.6 + 0.3 mm and for the particle size −1.18 + 0.6 mm. In electrostatic separation, the efficiencies obtained were higher for the smaller particle size (−0.3 mm).

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.

In the quarry sector, the reduction of landfill material may be obtained not only by finding a suitable recovery of the material as a by-product, but also by identifying the best available cutting technique to be used on the basis of the physical, chemical, and mechanical characteristics of the stones. The choice of the best cutting technique could lead to high efficiency and performance, high quality of the cut surfaces, and a very low environmental impact by reducing energy consumption, decreasing the concentration of heavy metals in the sludge, and producing less waste. In this context, an analysis of the procedures for cutting different types of ornamental stones into slabs together with the evaluation of sludge production for the different cutting methods has been carried out. Two types of analysis were carried out in parallel: evaluation of the stones workability and calculation of the amount of sludge produced in the three different cutting technologies and from the cutting of blocks. A comparison was carried out on the quality of the sludge produced, on type and quantity of metals present, taking into account the different cutting technologies. The performed tests were: chemical analysis, magnetic separation test, and SEM analysis of the metal fraction. The study could provide stone producers with a technological, scientific instrument to identify the best cutting techniques for the processing of their stones, in order to obtain a high-efficiency process, optimize the recovery process, increase the economic advantages, and evaluate the possible reuse of the sludge through a proactive waste management strategy.

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 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.