The influence of hydrochloric acid corrosion pretreatment on the flotation performance of hematite and its surface acid corrosion mechanism

This study systematically investigated the impact of Hydrochloric acid (HCl) corrosion pretreatment on hematite flotation within the NaOL system, analyzing the influence of varying HCl concentrations (measured as pH) on hematite acid corrosion. The results showed that at pH = 1, after 4 min of acid corrosion, hematite exhibited optimal floatability, achieving a recovery rate of 82.49 %, significantly surpassing the original ore. Conversely, at pH = 5, after the same duration of acid corrosion, hematite’s flotation is inhibited, yielding a recovery rate of 59.38 %, lower than the original ore. Through contact angle, adsorption amount measurements, and AFM detection, it is observed that after corrosion in pH = 1 HCl solution, hematite surface roughness increases, more NaOL collector is adsorbed, leading to significant hydrophobicity enhancement. After corrosion in pH 5 weak acid environment, despite increased surface roughness, hematite surface was coated with particulate matter, greatly reducing NaOL adsorption and further decreasing hydrophobicity. Further analysis using FTIR, XPS, and hydrolysis component calculation indicated that after acid corrosion in HCl at pH = 1, hematite exposed more active Fe sites, enhancing flotation performance. Conversely, at pH = 5, surface-dissolved Fe³⁺ transformed into hydrophilic Fe(OH)₃, inhibiting flotation by covering the hematite surface.