Dispersion and agglomeration mechanism of flaky graphite particles in aqueous solution

Understanding the collection behavior of gangue minerals in fine flake graphite flotation

“…The interaction forces, including Van der Waals energy (UA), electrostatic doublelayer interaction energy (UR), and the total interaction energy (UT), are described in Eqs. (2-5), respectively (Adair et al, 2001;Hamaker, 1937;Yangshuai et al, 2017;Mitchell et al, 2005):…”

“…Here, the Hamaker constants of graphite, mica, quartz, and feldspar in vacuum are 23.8 × 10 -20 J (Maurer et al, 2001), 9.86 × 10 -20 J (Bergström, 1997), 5×10 -20 J (Farahat, 2009), and 8.6 × 10 -20 J, respectively. When medium 3 is water (A33 = 3.7×10 -20 J) (Yangshuai et al, 2017), a value of the Hamaker constant of 3.59 × 10 -20 J was calculated for the mica/water/graphite system on the basis of Eq. 3; a value of the Hamaker constant of 9.00 × 10 -21 J was calculated for the quartz/water/graphite system, and a value of the Hamaker constant of 2.98 × 10 -20 J was calculated for the feldspar/water/graphite system.…”

“…Besides, other factors such as the surface roughness of the particles are also contributing (Yoon and Mao, 1996;Gomez-Flores et al, 2020). Our previous study (Yangshuai et al, 2017) on the interaction between fine flake graphite particles indicated that the aggregation of hydrophobic graphite particles is in better agreement with the XDLVO theory incorporating the hydrophobic interaction rather than the classical DLVO theory. Despite the previous studies regarding microcrystalline graphite and the interactions between fine flake graphite particles, the interactions between fine flake graphite and other gangue minerals have not been studied yet.…”

Modeling of the stability of water-based graphite dispersions using polyvinylpyrrolidone on the basis of the DLVO theory

“…Instable dispersions negatively affect the drop formation and the risk of nozzle clogging is increased [13] , [14] . Due to the strong attractive forces caused by the large particle surface, aqueous graphite [15] and graphene [16] nanoparticle dispersions are very prone to coagulation. Therefore, dispersants are needed to stabilize the particles in the medium [17] .…”

“…According to the theory in its original form, two major forces act on the particles in a dispersion, in particular the repulsive electrostatic forces induced by the electrochemical double layers and the attractive van-der-Waals-London forces. However, various studies have shown that the consideration of the forces postulated in the original DLVO theory alone is not sufficient to obtain a well-founded statement about the stability of all types of dispersions [25] , [15] . Accordingly, extensions of the DLVO theory have been elaborated over the years.…”