To provide a technique for enhancing density separation performance by using slurried dense media having a controlled particle size distribution.

This is a system for separating particulate mixtures and is a dehydrating screener having a first output port and a second output port as follows: a first density separator; supplied by the first output port of the first density separator, a second density separator; supplied by the second output port of the first density separator, a third density separator; and connected with the output port of the second density separator. The dehydrating screener removes a liquid from products generated from the output port of the second density separator. Thus, the system is provided with the dehydrating screener which is constituted so that at least one part of the removed liquid is to be supplied to the third density separator.