METHOD FOR COLLECTING RARE EARTH SLUDGE AND ENVIRONMENTAL LOAD REDUCTION METHOD

摘要

A method for collecting rare earth sludge according to the present invention includes: (A) a step for forming a depression in the sea floor by excavating a layer under the sea floor which includes rare earth sludge, and causing a state in which a slurry including rare earth is contained in the depression; and (B) a step for injecting a replacement material, which has a higher density than the slurry, into the depression, the slurry being lifted by a sludge raising mechanism located above the depression in step (B). An environmental load reducing method according to the present invention prevents the formation of low-oxygen regions in the sea water in the depression by maintaining the state in which the depression is filled with the substitute material after step (B) in the abovementioned method for collecting rare earth sludge.