水射流对钴结壳的破碎研究

【作者】 周玉军；

【导师】 刘少军；

【作者基本信息】 中南大学 ， 机械设计及理论， 2010， 硕士

【摘要】 随着陆地矿产资源的日趋枯竭和人类对海洋认识的日益深化,许多国家越来越重视海洋资源的开发和利用。深海钴结壳是大洋底部最具吸引力的矿产资源之一,产出在水深800-3000m的海山、岛屿斜坡上,其平均厚度仅为4-6cm,富含钴、铂、镍、锰、铜、铁、磷、钛、锌、铅、铈等战略物质。由于其巨大的战略意义和经济价值,深海钴结壳开采技术与装备的研究已成为国内外研究的一个热点。钴结壳开采研究的第一个难题和关键问题,就是如何从高低不平的海底基岩上将薄薄的一层钴结壳破碎剥离下来。钴结壳射流破碎方案为国际上推荐的两种可能开采方法之一,本文对该方案进行了基础研究,主要研究内容和研究结果如下：(1)建立了适用于破碎作业的高压水射流喷嘴的流体动力学仿真模型。(2)对深海环境下喷嘴水射流的内、外部流场进行了数值仿真分析,得到了5MPa,10MPa和15MPa三种典型围压环境下喷嘴内部射流压力、速度的变化规律和射流离开喷嘴后的压力、速度变化规律,并与非淹没状态下喷嘴射流的性能进行了对比研究。研究结果表明：随着海水围压的增加,喷嘴出口的最大速度相应下降,仿真结果与理论计算结果吻合,验证了选取的仿真计算方法基本合理；深海围压的大小对射流性能基本没有影响,不同围压下的喷嘴射流形成的等速核外形和最优靶距基本相同,深海最优作业喷距约为3倍喷嘴直径；与非淹没环境相比,淹没状态下喷嘴射流沿轴向速度衰减迅速,其等速核长度缩短约40%。(3)针对水的粒子特性,对水射流冲击破碎钻结壳和钴结壳模拟料建立了SPH粒子耦合有限元(FEA)模型,通过对不同系统压力下破碎结果分析：在相同条件下,钴结壳和钻结壳模拟料的成坑大小、成坑深度随射流速度增大相应增大。通过射流破碎钴结壳过程的观察,分析了射流破碎钴结壳的机理。(4)通过25MPa以下系统压力产生的水射流对钴结壳模拟料进行破碎实验得出：在非淹没环境下,随着系统压力的增加,破碎成坑大小和破碎成坑深度相应成增加趋势；钴结壳模拟料成坑深度随喷距的增大而减少,而成坑直径随喷距的增大而增大。在淹没环境下,破碎效果与非淹没条件下相比除了成孔孔径增大外,其他破碎效果基本一致。更多还原

【Abstract】 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.更多还原