This study proposes the use of polymeric nanoparticles (NPs) as collectors for copper sulfide flotation. The experimental phase included the preparation of two types of polystyrene-based NPs: St-CTAB and St-CTAB-VI. These NPs were characterized by Fourier-Transform Infrared (FTIR) spectroscopy and dynamic light scattering (DLS). Then, microflotation tests with chalcopyrite under different pH conditions and nanoparticle dosages were carried out to verify their capabilities as chalcopyrite collectors. In addition, the zeta potential (ZP) measurements of chalcopyrite in the presence and absence of NPs were carried out to study their interaction. Lastly, some Atomic Force Micrographs (AFM) of NPs and Scanning Electronic Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analysis of NPs on the chalcopyrite surface were conducted to analyze the size, the morphology and their interaction. The results obtained at pH 6 and pH 8 show that the NPs under study can achieve a chalcopyrite recovery near or higher than that obtained with the conventional collector. In this study, it was possible to observe that the NPs functionalized by the imidazole group (St-CTAB-VI) achieved better performance due to the presence of this group in its composition, allowing to achieve a greater affinity with the surface of the mineral.

Ceramic foams were fabricated without using melting pots through the direct foaming of compacted powder mixtures of commercial quartz (SiO₂) with fluxing agents (Na₂CO₃ and CaO) and a foaming agent (Na₂SiO₃·5H₂O) at a relatively low temperature range (850−870 °C). The effects of the pressing pressure of the powders, the foaming time, foaming temperature, and mixture content were evaluated. The obtained cellular solid materials presented an acceptable volumetric expansion at a pressing pressure of 4 t. The materials only presented porosity at a minimum temperature of 850 °C and at a minimum time of 30 min. All the foamed samples showed an acceptable symmetric expansion and non-appreciable fissures. The study of the mixture content through the statistical software MODDE® shows that the porosity of the samples was principally affected by the Na₂SiO₃ content and the foaming temperature. The samples obtained at the optimum controlling factors proposed by this statistical software presented an apparent density, porosity, and mechanical strength of 1.09 ± 0.03 g/cm³, 56.01% ± 1.12%, and 3.90 ± 0.16 MPa, respectively. Glass and ceramics foams such as those obtained in this work become attractive as insulation materials in applications where high temperatures occur due to their higher melting points.

The selective separation of molybdenite from copper sulfide concentrate in flotation process is realized using sodium hydrosulfide (NaHS) to depress the chalcopyrite and permit only the flotation of the molybdenite. However, this reagent is a highly toxic and flammable gas. The objective of this research was to study the feasible application of commercial lignosulfonates (LSs) in the separation by froth flotation process of molybdenite and chalcopyrite in seawater to present a novel application for LSs, as well as an alternative reagent to sodium hydrosulfide (NaHS). To achieve this, microflotation, absorbance tests and zeta potential measures were performed at pH 8 in seawater and 0.01 M NaCl. The results obtained in this study showed that it is possible to achieve selective separation of copper and molybdenum in both aqueous media due to high depressant effect of molybdenite and low depression of chalcopyrite in microflotation tests at 10 ppm of LSs, when the collector, PAX, is added prior to the addition of LSs. Absorbance study and zeta potential measurements showed that LSs adhere more to the molybdenite surface in seawater than in freshwater. This is related to the high ionic charge of the media that influences a greater interaction of LSs with the mineral surface.

Froth flotation is a process in which hydrophobic particles attach to bubbles forming particle–bubble aggregates, which are transported to the top section of the cell where they overflow to form the concentrate. Particles also reach the concentrate by entrainment, which is a non-selective process that leads to low concentrate grades. The objective of this work was to study and compare the degree of entrainment measured using three methods, in fresh and seawater, and using methyl isobutyl carbinol (MIBC) and DF-250 as frothers. The experimental results indicated that the degree of entrainment decreased in seawater. Besides, water recovery was lower in the experiments with seawater regardless of the frother that was used in the experiments, which correlated with the observed low degrees of entrainment. It is proposed that the reduction of entrainment and water recovery in seawater can be explained by a reduction of air recovery and/or more bubble coalescence in the froth. It is also proposed that surfactant diffusion/convection from the lamellae to the Plateau borders in the froth is reduced in seawater, which reduces the surface tension gradients, and thus the restoring liquid flow from the Plateau borders to the lamellae.

The widely used technology for the selective flotation of copper and molybdenite using sodium hydrosulfide (NaSH) to depress copper sulfides creates environmental issues related to the potential emissions of toxic hydrosulfide gas (H₂S) and bad odors. Previous studies showed that molybdenite flotation can be depressed by the action of lignosulfonates, but no significant progress has been made in studying the effect that these reagents have on the foaming/frothing phenomena in flotation. The objective of this work was to investigate the foaming properties of three samples of lignosulfonates through measurements of surface tension, foamability, bubble size distributions, and water recovery. A sugared sodium lignosulfonate (NaLS), a calcium lignosulfonate (CaLS), and a sample prepared by sulphomethylation of kraft lignin (KLS) were tested. It was found that all lignosulfonates displayed surface activity that decreased with pH and was related to the degree of anionicity and molecular weight. The NaLS lignosulfonate showed the highest dynamic foamability index (DFI) value, compared to that of the CaLS and KLS samples. The lignosulfonates tested in this study strongly affected bubble size. Water recovery tests performed using flotation experiments in a two-phase system showed that the KLS and NaLS samples had the strongest effect, which correlated with the surface tension, foamability, and bubble size results.