Because of the high cost and difficulty in the monitoring of underwater experiments of deep-sea mining equipment, this paper has developed a new polymetallic sulfide "mining and transferring" test platform. It realizes the basic conditions for conducting experimental research on deep-sea mineral mining, transfer, and delivery on land. The existing deep-sea mining systems and test platforms at home and abroad are investigated in this paper. It is determined that the test platform has the functions of mineral cutting, suction, secondary processing, storage, and lifting. To achieve the above functions, the test platform includes a pool, a high-power hydraulic source, a mobile crane, a cutting & collection module, a secondary processing module, a hose pump, a mineral separation module, a lifting pump, a buffer station, a cantilever crane, a centralized control room, etc. By establishing 3 circulation loops, the process of collection, transfer, and delivery can be tested individually or collaboratively. To ensure the productivity of the cutting & collection module, it is necessary to realize the automatic adjustment function of the cutting head's attitude. The kinematic model of the cutting arm is established and the range of motion is analyzed. The relationship between the vertical movement of the cutting head and the extension of the hydraulic cylinder is obtained by numerical calculation. Cement is used to simulate polymetallic sulfide mines, and the test platform is used to carry out linkage tests of mineral collection, transfer, and delivery. The test results show that the automatic adjustment function of the cutting head's attitude works well. The mineral cutting device developed has a production capacity of 45 t/h, and the particle size after the secondary processing of minerals is less than 30 mm.
Submarine polymetallic sulfide deposits generally occur at water depths of tens of meters to 3,700 m. They are characterized by higher purity metal content than onshore deposits. And these minerals are rich in lead, zinc, copper, gold, silver and other metals. The resource potential is very considerable. It has attracted exploration activities from various countries. Canada's Nautilus Minerals has completed the development and delivery of three deep seabed mining equipment for commercial mining of polymetallic sulphide mines in its exclusive economic zone in Papua New Guinea in 2018 (Kawano and Hisatoshi, 2022). In September 2017, METI and JOGMEC conducted the world's first successful seafloor polymetallic sulphide mining and collection test (Okamoto, et al., 2018). Before the 2017 Japanese continuously lifting test of seafloor massive sulphides, numerous on land excavation tests and 140 m long loop tests have been conducted since 2012 (Okamoto, et al., 2019). The Chinese research teams from Central South University, Changsha Institute of Mining Research Co., China State Shipbuilding Co., Chinese Academy of Sciences, and Shanghai Jiaotong University have carried out a lot of theoretical analysis and experimental research. Several collection system devices have been developed for different types of minerals (Peng, 2020; Liu, Liu and Dai, 2014; Cao, Du, Song, Lin and Yang, 2020). With a large number of offshore tests, several research institutions have established more complete technical solutions for the development of deep-sea mineral resources. The key technology development and core equipment development capabilities have been mastered. However, the cost of sea trials remains high due to various uncertainties from the harsh environment at sea. A more cost-effective solution is to establish the appropriate experimental facilities on land.
