Various types of thickeners of initial two-phase mixture are used in technological processes of hydraulic transportation of bulk materials. In recent years, especially abroad, thickeners of plate type, so-called Lamell have become widespread. The principal difference of these thickeners from the traditional ones, for example type Dora, is the division of the initial flow of thickened hydraulic mixture into a number of laminar flows by means of thin plates, installed obliquely in the body of the thickener, at some small, usually 30-50 mm, distance from each other.