Large-scale Experimental Study on Air-lifting System for Deep-sea Mining

The deep seabed is known for its abundant reserves of various mineral resources. They are nodular and unevenly distributed in seafloor sediments. Adhering to the principle of "who has the ability to develop first," countries worldwide have invested significantly in deep-sea mining research. To achieve the commercial exploitation of these seabed mineral resources, numerous deep-sea mining systems have been developed. Over decades, the combination of rigid and flexible risers supported by large surface mining vessels has become the mainstream approach in deep-sea mining systems. Within this huge industrial system, lifting polymetallic nodules from thousands of meters depth seabed to the surface is a very crucial step in deep-sea mining operations. The efficiency and operational stability of the lifting system directly affect the economic viability of the entire deep-sea mining process. Therefore, this article focuses on a commonly used air-lifting method in the deep-sea oil industry. A large-scale air-lifting experimental system has been established in a 20-meter-deep water tank to investigate the feasibility and efficiency of lifting water and nodules at various air-injection velocities. Detailed calculations are performed to determine the trends in water and nodule lifting efficiency. The original experimental data provides essential references for the future detailed design of lifting systems. This research offers valuable insights and guidance for the advancement of deep-sea mining technologies and equipment.