Inclusion of screening to remove fish-hook effect in the three products hydro-cyclone screen (TPHS)

Abstract

A novel three product hydro-cyclone screen (TPHS) has been developed at the Key Laboratory of Coal Processing and Efficient Utilization, China University of Mining and Technology, China for particle separation. The new hydro-cyclone consists of a cylindrical screen embedded in a conventional hydro-cyclone (CH), which combined both centrifugal classification and screening. The present study aimed to remove the fish-hook effect and demonstrate the performance of TPHS based on pilot-scale and industrial-scale experiments. In pilot scale, the screen aperture size varied in the range ∼0.50–0.70 mm, while the aperture size was 0.60 mm in case of industrial-scale. It found that the performance of hydro-cyclone significantly influenced by the aperture size. In contrast to the pilot-scale CH, the fines and the water recovery of TPHS in underflow were reduced and became less with the increase of aperture size, while the contrary trends of fines obtained in overflow. Furthermore, TPHS generated a new outgoing stream namely screen underflow due to the presence of a cylindrical screen, wherein the dominant size distribution was close to overflow. Note that the fish-hook effect was disappeared entirely in TPHS because the trapped and entrained fines in underflow reduced significantly. Also, the performance of both TPHS and CH was discussed based on the Hancock classification efficiency (HE), imperfection (I) and cut size (d50c) using the data obtained from the pilot-scale and industrial-scale experiments which indicate that TPHS represented a better performance than CH. A successful industrial-scale application of TPHS instead of CH in coal preparation plant demonstrated its advantage and application potential.