Abstract
The dispersion behavior of particles is of great significance in selective flocculation flotation. The interfacial interaction between coal and the main impurity mineral (kaolinite) particles with the effect of an anionic polyacrylamide (PAM A401) was explored by the extended Derjagin–Landau–Verwey–Overbeek (DLVO) theory. The involved surface free energy components of fine mineral particles were estimated using the van Oss-Chaudhury-Good theory and Washburn equation. After adsorption of PAM A401, the range and absolute value of the hydrophobic interaction VHA of the coal particles decreased, the electrostatic repulsive potential increased, and the total potential energy changed from −1.66 × 105 to −4.03 × 104 kT at the separation distance of 5 nm. For interactions between the kaolinite and coal particles after PAM A401 adsorption, the electrostatic repulsive potential increased and the hydrophilic repulsive potential energy decreased. The energy barrier at the separation distance of 0.2 nm decreased from 2.78 × 104 to 2.29 × 104 kT. The total potential energy between the kaolinite and coal particles after PAM A401 adsorption was still repulsive, and the range of the repulsive interaction increased from ~0.05 to 47 nm to ~0.05 to 50 nm. The total potential energy of the coal particles after PAM A401 adsorption was still attractive. This behavior of coal and kaolinite particles with the effect of PAM A401 indicates the possibility of enhanced fine coal separation by the method of selective flocculation flotation.
Highlights
Polyacrylamides (PAM), a kind of water-soluble polymer with a high molecular weight, are used extensively as flocculants and depressants in filtration, sedimentation, centrifugation, and flotation of mineral processing
Electrostatic attraction or repulsion between the charged polyacrylamide and the negatively charged kaolinite surface makes an effect on the adsorption [5,6,7]
The preferential adsorption of polyacrylamides onto the surface of coal was proven to depend on the dosage of the polymer and calgon [9]
Summary
Polyacrylamides (PAM), a kind of water-soluble polymer with a high molecular weight, are used extensively as flocculants and depressants in filtration, sedimentation, centrifugation, and flotation of mineral processing. Selective flocculation flotation using polyacrylamide is one of the efficient separation methods to separate ultra-fine minerals [1,2,3]. The adsorption of polyacrylamide onto kaolinite has been attributed to the hydrogen bonding between the silanol and aluminol OH groups at the particles’ surfaces and the polymer’s primary amide functional groups. Electrostatic attraction or repulsion between the charged polyacrylamide and the negatively charged kaolinite surface makes an effect on the adsorption [5,6,7]. The preferential adsorption of polyacrylamides onto the surface of coal was proven to depend on the dosage of the polymer and calgon [9]. The selective adsorption of polymers involving dextrin, guar, and amylose polysaccharide onto hydrophobic solids such as talc and coal is possibly associated
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