The tribological behavior of iron tailing sand grain contacts in dry, water and biopolymer immersed states

We investigated experimentally the tribological behavior of tailing grain contacts using a micromechanical apparatus which allows high precision of force and displacement measurements to derive contact stiffness. A technique was developed to apply biopolymer coating to the grain surfaces and the emphasis of the study was placed on the investigation of the influences of saturation conditions, the presence of polymer-based coating, and the abrasion on the frictional behavior of the grains. Material characterization was based on interferometry, micro-indentation and elemental composition analyses. Elastoplastic displacements dominated the first cycles of normal loading and the Young’s modulus was interpreted based on different contact models. The tailing grains showed significantly higher inter-particle friction compared with that of quartz grains. Three major characteristics which influenced the frictional behavior of the grain contacts were the abrasion, which was more dominant in the first loading cycles, the high roughness of the grains and the presence of the biopolymer coating which increased significantly the friction.