Abstract: Of the current deep-sea mining processes, hydraulic lifting is the most prospective. However, hydraulic lifting system involves an enormous investment and many risks, and in emergency, a rapid emptying of the piping may be required to ensure no blockage in the piping. The stress of the slurry in piping is analyzed, a formula of the movement of the slurry in the hydraulic lifting piping in deep-sea mining established and the relationship between the pulp discharging velocity in the lifting piping and the slurry concentration & pipe diameter discussed. On this basis, four rapid discharging schemes are proposed and compared for the design of a pilot system.

Key words: Deep-sea mining, Discharge velocity, Slurry concentration, Diameter of hydraulic lifting pipeline