Method for separation of particles using a rotating tilted open column with steady flow (RSF) — calculation of power index n(RSF)

Abstract

In the improvement of a rotating tilted liquid column (RTC) method (closed and open-bottom column systems), we have developed a method for rapid selective separation of particulate materials in a continuous or semi-continuous process: a rotating tilted open column with steady flow (RSF) method. The separation power of the RSF method is represented as (a j /a i ) n(RSF) , where a i and a j are radii of particles with the same density. The power index n(RSF) will increase with increase of the column rotation ω within the practical range of 1.3 ⩽ Aω/V 0 ⩽ 7, where A is the radius of the column and V 0 is the free falling velocity of the particle. From the relationship between particle loci and distribution of liquid flow speed, we derive an approximate equation to calculate n(RSF) practically and demonstrate the relationship 2 < n(RTC) < n(RSF). Further, n(RSF) takes a maximum value at θ = 0° when ω is fixed, and it sometimes exceeds the upper limit (= 4) of n(RTC) in the RTC method. This method can be of use for the separation of fine particles, easily degenerated micro-organisms, etc.