The production of superior metallurgical-grade silicon requires the use of ultra-clean coal containing <1.5% ash with no iron contamination. The magnetite suspension utilized for coal cleaning in a dense-medium cyclone (DMC) is a detrimental impurity in the final coal product that dramatically diminishes the purity of silicon. A prior study has demonstrated that several silica-based materials may be suitable alternatives that eliminate iron contamination. To further improve the separation performance and evaluate the silica-based media, DMC separation tests were conducted based on a statistically designed program to identify the role of various operational parameters (i.e. medium relative density, silica media blend ratio, and cyclone apex diameter) in maximizing organic efficiency and minimizing low-density bypass. An ideal medium composition with a bimodal particle size distribution considerably improves medium stability properties while also eliminating the undesirable effects of apex diameter on the DMC separation efficiency. Low-density cutpoints (<135) are hindered by medium instability, but these issues can be rectified by increasing the amount of fine media particles or decreasing the apex diameter. (C) 2016 Elsevier B.V. All rights reserved.