Phosphate ores, which are regarded as critical mineral resources, play an important role in various industrial fields. Apatite is the main source of phosphate mineral resources and must be concentrated before it is processed into industrial products. Flotation is the most commonly employed method for apatite concentration. However, as the proportion of fine apatite increases, the challenge of separating it from gangue minerals intensifies, due to the resemblance in surface characteristics between apatite and gangue. Interfacial regulation during flotation is fundamental to the process, including the regulation of the mineral/water interface wettability by flotation reagents (collectors and modifiers), the control of interactions between mineral particles, and the regulation of interactions between mineral particles and bubbles. This article introduces the surface characteristics of apatite and its main gangue minerals. It discusses innovative work on flotation reagents (primarily collectors and depressants) and their action mechanisms on mineral surfaces. It reviews the current development of theories on the regulation of interactions between interparticles and between particles and bubbles. Finally, the study outlook the future research on interfacial regulation in apatite flotation. This study is intended to offer references for the continued advancement of apatite flotation.

To enhance the performance of the combined high-pressure grinding roller (HPGR) and tower mill (TM) process for −1 mm particle size, this study addresses the key technical challenges of insufficient material quantity (<100 kg) and complex experimental procedures in HPGR closed-circuit crushing tests by proposing a novel circulating load prediction method based on the principle of mass balance and first-order crushing kinetics. Using a side-flanged HPGR WGM 6020 installation, systematic −1 mm HPGR closed-circuit crushing tests were conducted on seven different ore samples under three specific pressing forces, with detailed characterization of the dynamic variations in product size distribution, specific energy consumption, and circulating load during each cycle. The results demonstrate that within the specific pressing force range of 3.5 N/mm² to 4.5 N/mm² when the crushing process reaches equilibrium, the circulating load stabilizes between 100% and 200%, while the specific energy consumption is maintained within 1–2.5 kWh/t. Notably, at the specific pressing force of 4.5 N/mm², both the circulating load and specific energy consumption rapidly achieve stable states, with ore characteristics showing no significant influence on the number of cycles. To validate the model accuracy, additional samples were tested for comparative analysis, revealing that the deviations between the model-predicted −1 mm product content and circulating load and the experimental results were less than ±5%, confirming the reliability of the proposed method.