The ongoing expansion of global industry in the 21st century has accelerated the demand for critical metals such as iron, titanium, zirconium, and hafnium. Insular coastal placer deposits have emerged as a potential supplementary resource due to their extensive distribution. Mineralogical analysis of the Hainan Insular Coastal Placer (HICP) from Hainan Island, China, revealed a quartz-dominated assemblage with highly liberated ilmenite and magnetite (Fe–Ti carriers) as well as zircon (Zr–Hf carriers). In contrast, rutile (a Ti carrier) occurred predominantly in intergrowth with other minerals. Particle size distribution analysis demonstrates titanium enrichment in the 0.074-0.15 mm fraction (52.37%), while zirconium and hafnium concentrate in finer fractions (0.0385-0.074 mm). Based on the properties of the HICP, a processing flowsheet was developed involving ‘offshore gravity separation – magnetic separation – grinding and electrostatic separation – in-situ tailing disposal, onshore flotation’. This process enabled the beneficiation of low-grade feed (Fe 1.58%, TiO₂ 0.25%, ZrO₂ 0.07%, Hf 0.001345%) into high-grade concentrates (Fe 63.02%, TiO₂ 40.90%, ZrO₂ 37.05%, Hf 0.68%). The process achieved a 93.2% tailings discharge rate through ship-based in-situ disposal, which reduces ecological impact, lowers ore transportation volume, and alleviates the burden on terrestrial tailing storage facilities. The proposed method not only enhances process efficiency but also establishes a sustainable framework for marine mineral extraction.