The effect of ammonium polyacrylate (PAAA), anionic polyacrylamide (APAM) and hydroxamic acid flocculant (HPAM/HCPAM) on the settling performance of hematite and goethite by simulating the Bayer red mud settlement was studied, and the particle size distribution and fractal dimension of flocs as well as the flocculation mechanism were analyzed by Fourier transform infrared spectroscopy. Among the different types of flocculants, the iron ore phase sedimentation rate is the fastest with the addition of hydroxamic acid flocculant, and the higher the hydroxamic acid content, the better the sedimentation performance; the ammonium polyacrylate and anionic polyacrylamide flocculants have little effect on the settling performance of iron-bearing minerals; under the same conditions, the settling velocity of hematite is much higher than that of goethite, and increasing the amount of flocculant helps to improve the settling velocity of goethite. Among the hematite flocs, the PAAA flocs have the largest particle size, while the HPAM flocs have the largest fractal dimension and the best compactness; among the goethite flocs, the APAM flocs have the largest particle size, while the HCPAM flocs have the largest fractal dimension and the best compactness. The hydroxamic acid flocculant forms a five membered ring chelate with a stable structure and strong adsorption capacity with hematite and goethite, which enhances the flocculation performance of hematite and goethite; PAAA is adsorbed with hematite through bidentate bridging, and adsorbed with goethite through monodentate coordination, the adsorption capacity of which is weaker than five-membered ring; APAM adopts the chemical adsorption with hematite and goethite with a poor settling performance. © 2022 Chemical Industry Press. All rights reserved.
