Investigation of chromite preconcentration by comminution

Abstract

Chromite is the main source of chromium. It is widely used in metallurgical, refractory and chemical engineering applications. Chromite occurs in earth crust generally with serpentine minerals as associated gangue. Serpentine minerals, hydrated alteration products of olivine minerals, are softer than chromite. Therefore, controlled size reduction is thought to be a beneficial way of chromite ore pre-concentration. This study was conducted to determine the possibility of chromite concentration by controlled-comminution and then by classification. Size reduction was conducted first by laboratory scale blake type jaw crusher, and then rod and ball mills. Product quality was assessed using loss on ignition (LOI, %) as a measure. Experimental results revealed that LOI value of chromite ore sample was 8.22%. Sufficient liberation was not achieved by crushing. Then, crushed ore sample was subjected to rod mill grinding for 5 minutes. But, phase segregation was thought not to be achieved sufficiently. Then, further grinding was applied on rod mill-ground product: 5/10min grinding by rod mill and ball mill. However, fine grinding by rod and ball mills resulted in more even distribution of high LOI value serpentine minerals among the product size ranges. Selective separation could not be achieved by comminution at finer sizes. Perfect correlation could not be seen between hardness and grindability of minerals constituting chromite ore. Copyright © IMCET 2019 International Mining Congress and Exhibition of Turkey. All rights reserved.