Water Jet Cobalt Crusts Broken

Deep sea mining is a field of mining which attracts more and more attention from all over the world, it is considered as an important means to meet the challenge of the gradually exhaustion of land mineral resources.Cobalt-rich Ferromanganese crusts,which grows in the seamount,slope of islands ranged from 800 to 3000m is one of the most attractive mineral resources in the deep sea bed.Its average thickness is only 4 to 6 centimeters, and it is rich in strategic resources such as cobalt, platinum, nickel, manganese, copper, iron, phosphorus, titanium, zinc, lead and cerium etc.Because of its practical strategy, economic and political significance, Cobalt-rich Ferromanganese crusts has become a great concern in ocean resource exploitation in every country.The first problem of mining Cobalt-rich Ferromanganese crusts is how to crush the thin layer of Cobalt-rich Ferromanganese crusts from fluctuant surface of bedrock.One of two possible mining method recommended in international of mining Cobalt-rich Ferromanganese crusts is hydrojet.In this paper,the basic research was carried out for the program, the main conclusions of the paper are showed as follows:(1) High-pressure nozzle's fluid dynamics simulation model which suitable for break work is established.(2) The internal,external flow field and the performance of water jets of nozzle which work in deep-sea is carried out in the numerical simulation, in three typical confining pressure environment 5MPa, lOMPa and 15MPa, water jet's pressure and speed of nozzle internal changes in laws and water jet's pressure and speed changes in laws after leaving the nozzle were obtained,and non-submerged water jet's performance of nozzle is comparatively studied. The simulation results show that:with confining pressure increasing,the largest export speed of nozzle declines correspondingly,the simulation value coincides with the theoretical value,which verify the simulation method of selected is basic rational;the size of confining pressure under submerge environment doesn't affect its performance,The form of nozzle water jets'isokinetic core is similar and the optimal distance from the target is the same at different confining pressure,Optimal spray distance is about 3 times of the nozzle diameter; the axial velocity of submerged jet decay rapidly than non-submerged water jet, whose length of the isokinetic core is about 60% of non-submerged.(3) For the particles characteristic of water, the SPH particles coupled finite element (FEA) model for the Cobalt-rich Ferromanganese crusts and the simulaed Cobalt-rich Ferromanganese crusts matrials was broken by the water jet was established. The breaking results are analyzed under the different systems pressure as follows:under the same conditions, the crater size and cut depth of Cobalt-rich Ferromanganese crusts and the simulated Cobalt-rich Ferromanganese crusts materials increasing with the increasing of water jet velocity.The process of Cobalt-rich Ferromanganese crusts was broken by the water jet was observed, the mechanism of Cobalt-rich Ferromanganese crusts was broken by the water jet was analyzed.(4) The simuled Cobalt-rich Ferromanganese crusts materials was broken by the water jet generated under 25MPa pressure. In the non-submerged environment, the crater size and cut depth of Cobalt-rich Ferromanganese crusts increases corresponding to the increasing of crushing pressure.The cut depth of the simulaed Cobalt-rich Ferromanganese crusts materials decreases with the increasing of spary distance.but the crater size increases corresponding to the increasing of spary distance.In this experiment,with the exception of the crater size increasing,the crushing effect between submerged conditions and non-submerged conditions is basically the same.