This paper presents the research program of automatic control of hydraulic lift for nodule hoist from the collector to mining vessel and positioning of the lift pipe. It includes measurement of lift operational parameters, adjustment and control of these parameters, controlling principle and program, and positioning lifting system. The automatic control method presented in this paper was based on 150-m deep underwater hoisting of artificial nodule test.
As an important part of deep-sea mining system, hydraulic lift is regarded as one of most prospective lifting methods after some research and comparison were made on all lifting methods. Hydraulic lifting system in deep-sea mining is an integration of hose, hose transporting pump, buffer, lifting pipe, two multi-stage submersible motor pumps, transporting pipes on mining vessel and seawater overflow discharge pipe string, etc. Manganese nodules collected by collector are transported to the buffer through hose by hose transporting pump; then fed into steel lifting pipes with feeder and lifted up to the surface mining vessel by two multi-stage submersible motor pumps. Since the lifting system is the connection between collector and mining vessel, also the passage for the nodule slurry, the control system consequently plays one of the key roles. In accordance with the deep-sea mining technology, automatic control of lifting system was proposed in this paper to meet the requirement of the deep-sea mining test. When the changes on the lift parameters possibly bring some danger to the operation, automatic adjustment and control will be made according to the accumulative value. Previous R & D works published in 1980−2001 by us and other researchers are referred to those as listed in the References: Ship-pipebuffer- miner systems, pipe positioning, lift pump developments. In this paper our work emphasizes the automatic control of hydraulic lift.