集鉱機の付着滑り運動に伴う濃度変動に関する研究 （第１報） 濃度変動の発生ならびにその伝播について

Abstract

In the ocean mining tests of manganese nodules, which will be done at offshore of Hawai, it is expected that concentration fluctuation will occur in a lifting pipe owing to collector's stick-slip movement.In this paper amplitude of concentration fluctuation was studied experimentally.And propagation properties of concentration fluctuation were calculated by the diffusion model that mean eddy diffusivity for mass at a cross section of pipe was estimated.By using this model the amplitude and frequency of these fluctuations at an arbitrary point of lifting pipe could be estimated. Main results were as follows.1) According to the results of the model-testings, collector's stick-slip movement introduced concentration fluctuation in a lifting pipe.2) The amplitude of concentration fluctuation amounted to 60% of the time-average value in case the frequency of the oscillation of the collector model was 0.35Hz and that its amplitude was 0.50m.3) As the frequency of the collector's oscillation became high and as its amplitude increased, the amplitude of concentration fluctuation increased.4) According to the simulations of the concentration fluctuation's propagation, the amplitude of the concentration fluctuation decreased small with the distance from the outlet of the feeder.