Aggregates characterizations of the ultra-fine coal particles induced by nanobubbles

From Microbubbles to Nanobubbles: Effect on Flotation

“…The flotation performance (both recovery and kinetics) of ultrafine coal particles was said to be remarkably improved in the presence of nanobubbles; particle aggregates induced by nanobubble bridging has been recognized as one of the main contributors to improve the flotation performance of minerals [60]. It is generally believed that bubble miniaturization should be of significance to improve flotation efficiency [61].…”

Effective Separation of High-Ash Fine Coal Using Water Containing Positively Charged Nanobubbles and Polyaluminum Chloride

“…Particles. While in the previous research, the enhanced combustible recovery in coal flotation using water containing NBs was attributed to the intensified aggregation of fine coal particles induced by NBs, 10,21 the boosted combustible recovery using PCNB water could also be related to a modified interaction between coal particles. To justify this, the particle size distribution of clean coal in different waters with and without the addition of PAC was measured, and the results are shown in Figure 6.…”

“…As can be seen that when tap water was replaced by NB water, the size distribution of the same coal sample shifted to the right and the D90 increased to 265.66 μm. This may be due to the accommodation of NBs onto coal surfaces, and the hydrophobic attraction originating from the bridging of NBs causes more coal particles to aggregate . More importantly, the D90 of the coal sample was further increased to 312.69 μm when immersed in the PNCB water, the highest in the four different water solutions, suggesting the most intensified aggregation of coal particles in the presence of PNCBs.…”

“…Compared to the flotation using tap water, the use of NBs alone increased the overall combustible recovery from a baseline of 54.2–67.1% in NB water. The beneficial effect of NBs on coal flotation has been widely acknowledged in the literature. − However, after adding PAC to NB water, the ability of NBs to enhance coal flotation was compromised, as suggested by the relatively lower cumulative combustible recoveries in the group of NB water + PAC. A similar decline in combustible recovery using NB water after PAC addition has previously been reported by Li et al, who attributed it to the reduced surface hydrophobicity of coal in the presence of PAC.…”

“…This may be due to the accommodation of NBs onto coal surfaces, and the hydrophobic attraction originating from the bridging of NBs causes more coal particles to aggregate. 21 More importantly, the D90 of the coal sample was further increased to 312.69 μm when immersed in the PNCB water, the highest in the four different water solutions, suggesting the most intensified aggregation of coal particles in the presence of PNCBs. While it was revealed that PNCBs are positively charged at neutral pH by the ζ-potential measurement, the coal surface was noted to be negatively charged at the same pH.…”