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Application Of Solid Buoyancy Materials In The Lifting System

Raising ore is an important part of the deep-sea mineral resource mining technology. It can be used for the mining of different minerals. It is a common technology in the deep-sea mining technology system. In the deep-sea mining system, the lifting system is affected by a variety of random factors, and the working environment is particularly harsh. During the mining process, the lifting system is not only used to transport nodules, but also to pull the mining machine, and it is also the support of the cable body. Therefore, it can be said that the mining system is the most critical equipment in the mining system and the artery of the mining system. The function of the raising ore subsystem is to lift the collected nodule ore to the surface mining vessel via the pipeline. The research and development results at home and abroad and deep-sea mining tests show that slurry pump hydraulic lifting and gas lift pump lifting are realistic, feasible and most promising methods of ore lifting, which are valued by all countries. At the same time, slurry pump lifting has a series of advantages such as simple technology, mature technology, high reliability, and high efficiency, and its efficiency is several times higher than that of gas lift pumps, and it will be the first to be adopted by commercial mining. The deep-sea mining operating environment is complex and changeable, and its technology is a series mining system, which requires simple mining technology and high operational reliability.

The upper end of the ore lifting hard pipe of the ore lifting subsystem is hinged with the mining ship, and the two ends of the lifting pump are connected with hard pipes. The rigid pipe is 900m long and has geometrically nonlinear large deformation characteristics; the hose length is about 300~400m. The entire lifting system is a complex long pipeline multi-body system with geometrically nonlinear and large deformation characteristics. The main factors that have a greater impact on the underwater spatial morphology and dynamic behavior of the lifting system include: ① environmental loads such as waves and currents; ② The material characteristics and structural parameters of each part of the system; ③The connection method and relative spatial position between the various parts of the system; ④The configuration and size of the concentrated buoyancy of the hose; ⑤The movement state of the ore ship and the mining machine.

The solid buoyancy material is used in the lifting system, mainly for weighting the lifting pipeline, adjusting the buoyancy state of the lifting pipeline under water, and ensuring the normal and stable operation of the entire system. In order to ensure that the mining machine travels on a predetermined trajectory on the seabed and reduce the drag of the hose to the mining machine, the flexible hose needs to form a saddle shape under the concentrated buoyancy provided by the two floating bodies and float in the sea water. in. This spatial form of the hose underwater allows the mining machine to have a larger range of motion to increase the collection rate, and can compensate for the height of the lifting system when the mining machine changes with the terrain height.

The bending stiffness of the lifting hose is small, and the spatial configuration changes greatly during the entire mining process, and it is the most direct approximation of the movement of the mining machine. Therefore, it is necessary to pass system static analysis to calculate and determine the given boundary conditions. The spatial shape and force state of the lower ore lifting pipeline system, the coordinates and rotation angles of each node of the pipeline, the axial stress, radial stress, and shear stress in each unit of the pipeline, as well as the reaction force and moment at the boundary .

Therefore, the hanging position of the solid buoyancy material used in the lifting system is also very important. The system space form of the 400m (with 125.5kN concentrated buoyancy) hose obtained by static calculation. Since the middle warehouse is only 100m away from the seabed, when the hose is 400m long, the middle warehouse has a relatively small drag on the mining machine, and the safe movement range of the mining machine is large. The hose can form a better saddle shape underwater. The size of the concentrated buoyancy generated by the suspended floating body is very sensitive to the influence of the spatial shape of the hose. Excessive buoyancy will cause the hose to pull too much force on the mining machine and the intermediate bin. After a series of calculation results, the total buoyancy range should be 95% to 105% of the total mass of the hose in the water (including the slurry in the pipe), and the buoyancy at the hanging position of the first floating body is 1/3 of the total hanging buoyancy. The buoyancy of the suspension of the two floating bodies is 2/3 of the total buoyancy, which can form a better tube shape.