Polyacrylic Acid to Improve Flotation Tailings Management: Understanding the Chemical Interactions through Molecular Dynamics

Abstract

Molecular dynamic simulations of polyacrylic acid polyelectrolyte (PAA) analyzed its interaction with the main minerals that make up characteristic tailings of the mining industry, in this case, quartz, kaolinite, and montmorillonite. The simulations were carried out with the package Gromacs 2020.3. The interaction potentials used were General AMBER Force Field (GAFF) for PAA and CLAYFF-MOH for mineral surfaces. The SPC/E model described water molecules and Lennard-Jones 12-6 parameters adjusted for SPC/E model were used for Na+ and Cl− ions. The studied systems were carried out at pH 7, obtaining stable adsorption between the PAA and the studied surfaces. Interestingly, the strongest adsorptions were for montmorillonite at both low and high salt concentrations. The effect of salinity differs according to the system, finding that it impairs the absorption of the polymer on montmorillonite surfaces. However, a saline medium favors the interaction with quartz and kaolinite. This is explained because montmorillonite has a lower surface charge density and a greater capacity to adsorb ions. This facilitated the adsorption of PAA. It was possible to identify that the main interaction by which the polymer is adsorbed is through the hydroxyl of the mineral surface and the COO−Na+ complexes. Molecular dynamics allows us to advance in the understanding of interactions that define the behavior of this promising reagent as an alternative for sustainable treatment of complex tailings in highly saline environments.

Understanding the Behavior of Sodium Polyacrylate in Suspensions of Silica and Monovalent Salts

“…The methodology to build molecules follows our previous work [13,36]. To accomplish this, the polymer NaPA was meticulously designed, comprising 48 acrylate monomers (-CH 2 -CHCOO − -), which underwent complete dissociation due to the monomers' pKa of 4.5.…”

“…In the context of mineral processing, it finds common usage in the mining industry as a dispersant additive for enhancing the flotation stage's efficiency and improving tailings fluidity. NaPA is watersoluble; its salts are neutralized at molecular masses up to 100,000 g/mol [11][12][13]. This constitutes a fundamental consideration, given its significant impact on rheological properties and dispersion behavior.…”

Exploring the effect of a polyacrylic acid-based grinding aid on magnetite-quartz flotation separation

“…PAA was selectively adsorbed on calcite, selectively depressed, and improved fluorite recovery with sodium oleate at pH 7. Quezada et al [24] reported that applying PAA could improve the sedimentation and storage of quartz, montmorillonite, and kaolinite flotation tailings. Through molecular dynamics simulation, PAA was reported to adsorb on quartz and clay mineral surfaces, ultimately preventing agglomeration of the tailings and allowing easy dewatering.…”

Substituent Effects in Kaolinite Flotation Using Dodecylamine: Experiment and DFT Study

“…The results showed that, with the increase of the average molecular weight of sodium petroleum sulfonate, the flotation recovery of fluorite gradually decreased. Quezada et al [16] used Gromacs software to study the adsorption behavior of polyacrylic acid polyelectrolyte (PAA) on the surface of quartz, kaolinite, and montmorillonite. Molecular simulation can not only be used to reveal the interaction between collectors and kaolinite [17][18][19], quartz [20][21][22], fluorite [23], and other crystal minerals [24,25] but also can simulate the interaction between coal and collectors [26].…”