Studies on the System for Developing Cobalt-Enriched Crust-Deposit in the Deep Sea

在1987年财政年度，根据已发表的文献资料，对富钴结壳存款的地质、物理性质和开发系统进行了研究。指出了水力疏浚法的诸多优点，提出了开发存款的疏浚优化系统。该系统由海面采矿船、海底采矿机器人以及连接采矿船和海底采矿机器人的管线组成。具体地说，管柱的中部有一个泵模块，下端有一个缓冲器，缓冲器通过一个柔性管道与采矿机器人连接。此外，为了确定作用在泵组件和缓冲器上的流体力，还用本文提出的新方法分析了各种泵组件和缓冲器的阻力系数和附加质量系数。上述情况下管柱的纵向振动对采矿船在海况外力作用下发生垂向振动时的振动控制系统进行了理论分析。第一次共振是可能发生的，也是无法避免的，但可以通过改变泵模块和缓冲器的分布、质量比和形状来减小泵模块和缓冲器的共振幅值。通过选择合适的泵模块和缓冲器的分布、质量比和形状，可以减小管柱顶部产生的最大轴向应力，最后发现采用较大阻力系数的泵模块和缓冲器是减小上述幅值和应力的最有效方法。

In the fiscal year of 1987, the geology, physical property and developing system of the cobalt-enriched crust deposit were studied by the references which had been already published. Then, the pollowing optimum system for developing the deposit was proposed by pointing many advantages of the hydro-dredge method. This system was composed of a mining ship on the sea surface, a mining robot on the sea bottom and the pipe-string connecting the ship with the robot. In detail, the pipe-string had a pump-module in the middle part and a buffer in the lower end which was connected with the mining robot by a flexible pipe. Furthermore, in order to determine the fluid forces acting on the pump-module and buffer, the drag and added-mass coefficients for various pump-modules and buffers were analysed by the new method developed in this study.In the fiscal year of 1988, based upon the results obtained in the previous year, the longitudinal vibration of the pipe-string in the above-proposed system was theoretically analysed when the mining ship was forced to vibrate vertically by the external forces due to the sea-state. Then, it was realized that the first resonance could occur and might not be avoided, but that the resonance amplitudes of the pump-module and buffer could be reduced by changing the distribution, mass-ratio and shape of the module and buffer. Furthermore, the maximum axial-stress produced at the top of the pipe-string could be reduced by selecting the proper distribution, mass-ratio and shape of the pump-module and the buffer.Finally, it was found that the most effective method to reduce the above-mentioned amplitude and stress was to use the pump-module and buffer with larger drag-coefficient.