Technique to determine the parameters of a plate thickener for silicate extraction from fly ash of coal thermal power plants

Abstract This study aims to develop a methodology for calculating the parameters of a plate thickener designed to separate the non-carbonaceous (mainly silicate) fraction of fly ash from coal thermal power plants in an upward flow while simultaneously enabling counter flow of sands. The methodology is based on analytical and experimental data on the sedimentation velocity of ash particles in pulp. Unlike existing calculations, the proposed approach accounts for a significant flow of heavier aluminosilicate fractions that occupy a considerable portion of the space between plates during separation and downward sliding along the plates. The primary focus of the study is on the calculation of density and sedimentation velocities for two fractions: carbonaceous and non-carbonaceous. Analytical calculations utilize the well-established Stokes and Wenk equations to estimate pulp viscosity and particle settling velocities. The method accounts for average particle density, pulp density, solid phase concentration, and geometric plate parameters. The optimal gap between plates is determined to ensure laminar flow. A practical example demonstrates the effectiveness of the proposed methodology for separating narrow fly ash fractions from the Prydniprovska TPP. The results indicate the potential for near-complete purification of the silicate fraction from carbonaceous particles, promising both economic and environmental benefits.