Abstract: Interfacial interactions between rough mineral particles have garnered considerable attention as they directly determine particle agglomeration and floatability. This study comprehensively investigates the agglomeration characteristics of siderite particles after argon (Ar) plasma surface modification through settling tests, flocs size measurements, and fractal dimension calculations. Ar plasma surface modification promotes the agglomeration of siderite particles, as evidenced by increased floc size and density. The agglomeration mechanism induced by Ar plasma surface modification is evaluated using a theoretical model combining the surface element integration (SEI) approach, differential geometry, and the composite Simpson’s rule. Changes in surface roughness, wettability, and charge are considered in this model. Compared to the unpretreated siderite particles, the energy barrier for interaction of the 30-min Ar plasma-pretreated siderite particles decreases from 2.3 × 10⁻¹⁷ J to 1.6 × 10⁻¹⁷ J. This reduction provides strong evidence for the agglomeration behavior of siderite particles. Furthermore, flotation experiments confirm that Ar plasma surface modification is conducive to the aggregation flotation of siderite. These findings offer crucial insights into particle aggregation and dispersion behaviors, with notable application in mineral flotation.