In this paper, ultrafine iron tailings from the Makeng Iron Mine in Longyan city, Fujian Province, were used as the research object. A four-factor three-level orthogonal test method was used to study the sedimentation characteristics of ultrafine tailings with four common curing agent materials, including polyacrylamide, polyaluminum chloride, polyaluminum sulfate and polyferric sulfate. The results show that when the pulp concentration is 30%, the polyacrylamide is cationic and the molecular weight is 10 million, the optimal content of the flocculant is 3%o; the optimum dose of the polyaluminum chloride with a content of 28 is 0.1%o; the optimum dose of polyaluminum sulfate is 1%o; and the optimum dose of polymeric ferric sulfate is 1%o. When the flocculant is mixed according to the proportion of 2%o polyacrylamide, 0.05%o polyaluminum chloride, 1%o polyaluminum sulfate, and 1.0%o polyferric sulfate, the sedimentation speed of the ultrafine tailings is fast, and the supernatant liquid is clear. After multivariate nonlinear regression analysis of the sedimentation curve, the results show that the primary and secondary factors affecting sedimentation are polyacrylamide > polyaluminum sulfate > polyaluminum chloride > polyferric sulfate. After applying the best ratio, the cohesion (c) of ultrafine tailings increases from 27 kPa to 68.75 kPa, and the internal friction angle (φ) increases from 25.53° to 27.53°, which shows that the shear strength improves, and the stability of the tailings dam increases.

China is a major producer of mined materials and possesses some of the richest mineral resources in the world. Mineral resources are abundant, and the reserves and production are among the highest in the world[1]. Ultrafine tailings have a small particle size, so they have a large specific surface area and high reactivity[2]. In recent years, domestic and foreign research on flocculation and sedimentation has been carried out at both the macroscale and the microscale; for example, Eswaraiah[3] and other scholars studied the sedimentation characteristics of ultrafine iron tailings. Selomulya[4] et al. used optical laser microscopy and X-ray diffraction to study the microstructure of floc particles and sedimentary layers.

In this paper, ultrafine tailings from the Mikang Iron Mine in Fujian Province were used as the research object. This paper selected curing agent materials comprising polyacrylamide, polyaluminum chloride, polyferric sulfate, and polyaluminum sulfate, which are good flocculants for the sedimentation of ultrafine tailings slurries.

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