Water bottom resource collecting method

Abstract

A mining riser pipe is extended toward a water bottom, and a lower portion of an insertion pipe connected to a lower portion of the mining riser pipe is inserted into the water bottom. A liquid is supplied into the insertion pipe, and a rotation shaft extends inside both pipes and stirring blades attached to a lower portion of the rotation shaft are rotated inside the insertion pipe, thereby drilling and dissolving mud inside the insertion pipe into a slurry. Then, the mud S is raised to an upper portion of the insertion pipe by a stirring flow generated by the stirring blades, and the raised mud slurry is lifted above the water through the mining riser pipe, and a rotation speed of the stirring blades is lower in an initial process at an early stage of the drilling than in a subsequent process.