An Assessment of the Role of Combined Bulk Micro- and Nano-Bubbles in Quartz Flotation

Abstract

Bulk micro-nano-bubbles (BMNBs) have been proven to be effective at improving the flotation recovery and kinetics of fine-grained minerals. However, there is currently no research reported on the correlation between the properties of BMNBs and flotation performance. For this purpose, aqueous dispersions with diverse properties were created by altering preparation time (0, 1, 2, 3, 5, and 7 min), aeration rate (0, 0.5, 1, 1.5, and 2 L/min) and aging time (0, 0.5, 1, and >3 min). Micro- and nano-bubbles were characterized using focused beam reflection measurements (FBRM) and nanoparticle tracking analysis (NTA), respectively. The micro-flotation of quartz particles was performed using an XFG-cell in the presence and absence of BMNBs with Cetyltrimethylammonium bromide (CTAB) as a collector. The characterization of bubble sizes showed that the bulk micro-bubble (BMB) and bulk nanobubble (BNB) diameters ranged from 1–10 μm and 50–400 nm, respectively. It was found that the preparation parameters and aging time considerably affected the number of generated bubbles. When BNBs and BMBs coexisted, the recovery of fine quartz particles significantly improved (about 7%), while in the presence of only BNBs the promotion of flotation recovery was not significant (2%). This was mainly related to the aggregate via bridging, which was an advantage for quartz flotation. In comparison, no aggregates were detected when only nano-bubbles were present in the bulk solution.

Limitations of the Nano-Bubbles Application for Beneficiation of Fine and Ultrafine Particle Flotation

“…We have used the data presented in [32] to produce the illustrative example shown in Figure 1 of the approximate frequency distribution of bubbles by size, which demonstrates that NB concentrate in the size range of 0.05 -0.5 µm, MB concentrate in the range of 10 -1000 µm, whereas in the range of 1-10 µm there are practically no bubbles. This fact suggests that it is possible to separate NB from MB by the sedimentation of the latter, as was done in [31,33]. Recent theoretical studies [34][35][36] have shown that the existence of stable NBs and their absence in the region of 1-10 μm can be attributed to the ratio of opposing capillary and electrostatic forces.…”

“…The efficiency of combined micro-and nano-flotation of quartz particles of the size of below than 60 µm has been explored in [33]. And the findings have demonstrated that the simultaneous application of NB and MB have improved the recovery of quartz recovery from 72 to 79%.…”

Enhancement Mechanism of the Difference of Hydrophobicity between Anode and Cathode Active Materials from Spent Lithium-Ion Battery Using Plasma Modification

“…During the flotation process, the impeller speed and air flow rate were set to 1000 rpm and 40 mL/min. Details of flotation operation procedures can be found in previous literature. , The froth products were recovered with four time intervals (0–0.5, 0.5–1, 1–2, and 2–4 min(s)) for a total flotation time of 4 min. All flotation products were collected and dried in a dryer (at 100 °C for 120 min) to determine their weight, mass recoveries, and kinetics.…”

Effect of Bulk Nanobubbles on the Flocculation and Filtration Characteristics of Kaolin Using Cationic Polyacrylamide

“…Nanobubbles (NBs) possess unique physicochemical properties, including large specific surface area, low terminal velocity, and long lifetimes, making them attractive for enhancing mineral flotation [33,34]. It is important to note that some of the literature defines NBs as both micro-scale and nano-scale bubbles [35][36][37]. Furthermore, there are two types of NBs used in mineral flotation: bulk and surface NBs [38][39][40][41].…”