Recently, the China Geological Survey reported that a panel of experts—comprising Academician Mao Jingwen of the Chinese Academy of Engineering, Academician Hou Zengqian of the Chinese Academy of Sciences, and other leading specialists in the rare-earth field from the Chinese Society of Rare Earths and the China Rare Earth Industry Association—recently reviewed the findings of the “Comprehensive Investigation and Evaluation of Paleosol Sedimentary Rare-Earth Deposits in the Adjacent Sichuan-Yunnan-Guizhou Region” project. The expert panel concluded that the paleosol sedimentary rare-earth deposits in the Sichuan-Yunnan-Guizhou adjacent region represent a brand-new type of rare-earth deposit with broad application prospects. This marks the official recognition of paleosol sedimentary rare-earth deposits as a new category of rare-earth resources with commercial development potential.
　　According to the head of the project’s research team, the Paleozoic continental sedimentary rare-earth deposits are hosted in the claystone beds at the base of the Permian Xuanwei Formation in the adjacent region of Sichuan, Yunnan, and Guizhou provinces. The average grade of rare-earth oxides in these deposits is 0.39%, with an average thickness of about 2 meters, and they are widely distributed. These rare-earth deposits exhibit a unique occurrence pattern: numerous nanoscale rare-earth-bearing mineral particles are embedded within the layered structure of clay minerals, making separation and beneficiation extremely challenging. After six rounds of intensive research and development, the Chengdu Institute of Mineral Resource Comprehensive Utilization, China Geological Survey, has successfully developed an environmentally friendly, short-process integrated beneficiation technology based on “nanocrystalline transformation—targeted rare-earth separation.” This technology has boosted the overall leaching rate of all rare-earth elements to around 90%, with the highest leaching rate reaching as high as 92.1%. At the same time, the leaching rates of major impurities such as aluminum, silicon, and iron are kept below 5%. The process has been validated through large-scale continuous pilot tests involving tonnage-level operations, yielding commercial-grade mixed rare-earth oxide products with a rare-earth oxide content exceeding 92%. This breakthrough has significantly accelerated the pace of commercial exploration and development. To date, nine new prospective areas for rare-earth exploration have been identified, and eight targeted exploration zones have been delineated.
　　Industry experts believe that continental sedimentary rare-earth deposits have distinct advantages over carbonate-rock and alkaline-rock rare-earth deposits in terms of mining conditions and the proportion of high-value and critical rare-earth elements such as praseodymium, neodymium, terbium, and dysprosium. Compared with ion-adsorption rare-earth deposits and deep-sea rare-earth-rich muds, these continental sedimentary deposits boast advantages in terms of grade, scale, concentration, and environmental impact, offering promising prospects for development and utilization. Their role as a replacement for southern ion-adsorption rare-earth deposits will gradually become more prominent, making them of great significance for enhancing China's capacity to secure its rare-earth resources.