Phosphate rock has been considered as one of the most significant secondary rare-earth resource, and the utilization of rare earth elements (REEs) in phosphate rock has attracted increasing attention. In this study, the leaching kinetics of REEs from a phosphate ore from China was studied with the variation of temperature and phosphoric acid concentration under the conditions: ratio of liquid to solid of 12 mL/g, stirring speed of 120 r/min, and phosphate particle size of −0.074 mm amounts 61.1%. The results suggest that there were two distinct stages in leaching process and kinetics of both stages followed shrinking core model. At fast reaction stage, the semi-empirical equation describing the kinetics was 1 − 3(1 − α)^2/3 + 2(1 − α) = 1.885CH₃PO₄^0.89exp(−11220/8.31T)t. The semi-empirical equation for slow reaction stage was 1 − 3(1 − α)^2/3 + 2(1 − α) = 0.299CH₃PO₄^2.50exp(−18720/8.31T)t. Using shrinking core model and time-to-a-given-fraction method, we found that leaching rate of fast reaction stage was controlled by solid product layer diffusion, and both solid product layer diffusion and chemical reaction determined slow reaction stage.

The separation of ultrafine apatite from quartz through reverse flotation is a challenge due to its low mass and high specific surface area. In this work, xanthan gum–Fe³⁺ (XG–Fe³⁺) was explored as a novel and efficient depressant–flocculant for the selective flotation separation of apatite and quartz. The flotation performance and separation selectivity of XG–Fe³⁺ were systematically assessed using micro-flotation tests. The mechanisms were revealed through turbidity analysis, microscopic observation, contact angle measurement, zeta potential, and Fourier Transform Infrared Spectroscopy (FTIR) analysis. Flotation results illustrated that XG-Fe³⁺ strongly depressed the flotation of apatite, while it hardly affected the flotation of quartz. Turbidity analysis and microscopic observation indicated the flocculation of fine apatite in the presence of XG-Fe³⁺, while no flocculation was found for quartz. Contact angle, zeta potential and FTIR results indicated that XG-Fe³⁺ was chemically adsorbed onto the apatite surface, hindering the adsorption of dodecylamine (DDA) and maintaining the hydrophilicity of apatite. XG-Fe³⁺ enhanced the flotation separation of ultrafine apatite from quartz by maintaining the hydrophilicity of ultrafine apatite while simultaneously reducing its entrainment into the froth via selective flocculation.

To satisfy the industrial standards for phosphate products, phosphate ore must undergo beneficiation for the removal of gangue minerals such as carbonate minerals, silicate minerals, and clay minerals. Reverse flotation is commonly used to remove carbonate minerals from apatite. However, reverse flotation removes carbonate gangue minerals but fails to eliminate silicate and clay minerals. The use of pre-concentration (such as dense-medium cyclones and photoelectric sorting) in phosphate ore beneficiation enables the early rejection of gangue before the ore enters the fine-grinding and complex flotation circuits, thereby providing a range of technical and economic benefits. In addition, pre-concentration holds the potential to reject silicate and clay minerals in the beneficiation of phosphate ore. The phosphate ore investigated in this study was obtained from Hubei, China. It is characterized by well-defined gangue banding, which facilitates the liberation of some gangue minerals at relatively coarse comminution sizes (−15 + 0.5 mm). Based on these characteristics, photoelectric separation and dense-medium cyclone separation were employed as pre-concentration methods prior to reverse flotation, with the aim of achieving economically viable recoveries and marketable product grades. The results indicate that the combined dense-medium cyclone separation–reverse flotation process was the most effective for this phosphate ore, producing a final concentrate with a P₂O₅ grade of 31.08% and a recovery of 81.91%. Comparative evaluation reveals notable differences in gangue removal efficiency among the tested processes. While both reverse flotation and the combined photoelectric separation–reverse flotation process effectively removed dolomite, the dense-medium cyclone separation–reverse flotation process demonstrated superior overall performance by enabling the simultaneous removal of both silicate and dolomite impurities.