Japan Tests Deep-Sea Yttrium Mining to Offset China Export Cuts

Japan is accelerating plans to mine deep-sea yttrium and rare earth elements within its exclusive economic zone as Chinese supply restrictions continue to choke Japanese buyers. Trade data indicates that shipments of yttrium and other critical minerals from China to Japan have fallen sharply amid worsening bilateral relations. The tighter export controls have constrained supplies of terbium, gallium, and dysprosium, leaving Japanese manufacturers exposed to overseas supply volatility.

The project is based near Minamitorishima, a remote island in the western Pacific approximately 1,900 kilometers southeast of Tokyo. Researchers have identified rare-earth-bearing mud on the seabed at depths of several kilometers, including deposits containing yttrium. While Japan has already demonstrated the ability to bring this material to the surface, the primary business challenge remains determining whether the process can operate at a scale and cost suitable for a reliable commercial supply.

Chikyu Vessel Completes Initial Recovery Test

In February, the research vessel Chikyu, operated by the Japan Agency for Marine-Earth Science and Technology, conducted a deep-sea recovery test near Minamitorishima. The vessel lifted rare-earth-bearing mud from a seabed depth of 5,569 meters, marking the world’s first continuous lifting of such material from that depth to a surface vessel. Researchers recovered approximately 50 metric tons of mud during an operation that began in January and concluded in mid-February.

Analysis of the recovered material revealed that medium and heavy rare earths accounted for about 54% of the identified rare-earth content. These elements include yttrium, gadolinium, and dysprosium. It is important to note that this percentage describes the composition of the rare-earth fraction, not the total mud volume, and the test did not establish the total size of the deposit.

2027 Pilot Scales Up Extraction Volume

Japan plans a larger, month-long test in 2027, during which crews will ship the recovered slurry to Minamitorishima for water drainage before transporting it to mainland Japan for separation, refining, and smelting. Officials project this operation will retrieve rare-earth mud at an average rate of about 350 metric tons per day. The results will be used to assess the economic and technical feasibility of domestic rare-earth production by March 2028.

The technical scope extends beyond mere extraction, requiring a continuous system for excavation, lifting, transport, and processing at depths approaching 6,000 meters. JAMSTEC is simultaneously testing methods to monitor the marine environment, having operated seabed and vessel-based systems during the recent test to track biological responses and environmental conditions. This integrated approach aims to address regulatory and environmental risks associated with large-scale seabed mining.

Strategic Shift Reduces Import Dependence

Yttrium is essential for specialized materials in aerospace and advanced manufacturing, sectors where Japan remains heavily reliant on imports. While China exported 29 metric tons of yttrium oxide to the United States in July, a relatively high volume since implementing controls, Japanese shipments face much tighter restrictions. This disparity underscores the urgency for Japan to develop a domestic alternative to secure its industrial supply chain.

According to GN auto stocks/materials: rare earths, the seabed project offers a potential domestic alternative to Chinese supplies. However, the initiative faces significant hurdles, including the need to determine the full extent of the deposit and prove that it can be extracted and refined at commercial scale. The success of the 2027 pilot will be critical in validating the economic viability of this deep-sea resource strategy.