DefinePK

Abstract

An in-plant experimental study was performed to evaluate the separation performance of five different spiral circuit configurations. The spiral circuit feed consisted of coal particles having a nominal size of 1 x 0.15 mm from the underflow of a bank of classifying cyclones. The experimental data obtained from this research study was mass balanced using spreadsheet-based routines, evaluated and compared for separation efficiencies and clean coal yield. It was determined that the best performance could be achieved using a four-staged circuit in which the clean coal passed through them. The high-ash refuse was removed after each of the four stages and middlings from the second and final stages were recycled back to the original feed. This circuit provided the best separation efficiency, cumulative clean coal yield and combustible recovery among all the other spiral circuits tested. At the same clean coal ash, the new spiral circuit increased the cumulative clean coal yield by 1.9 % as compared to that achieved using the existing two-staged compound spiral installed at the plant. It is also noticed that the repluping after two turns of spirals is not effective in improving the separation performance.