Work Index and Mineral Liberation Determination of a Complex Copper Ore: A Preliminary Step Towards Designing Sustainable Mineral Processing Flowsheets

Abstract

Work index provides critical information about an ore’s resistance to comminution, mineral liberation characteristics, and energy and time required for the comminution process. However, evaluating work index of ores is overlooked in many mineral processing operation and failing to assess work index of ores results in poor liberation of minerals, excessive energy losses and poor overall separation of valuable minerals. The aim of this study was to determine work index of Azara (Nigeria) complex copper ore and evaluate the liberation characteristics of the copper minerals. The evaluated work index of Azara complex copper ore was 13.90 kWh/t. Mineral liberation results from Mineral Liberation Analyser (MLA) showed 73.63% of malachite, 70.3% of chrysocolla, 52.66% of chalcocite and 24.25% brochantite particles were liberated at a grinding time of 90 minutes. With increasing of the grinding time, the liberation of minerals increased. At a grinding time of 180 minutes, the liberation of malachite, chrysocolla, chalcocite and brochantite improved to 86.72%, 76.66%, 74.14% and 53.27%, respectively. These findings provide new insights into the grinding conditions of Azara complex copper ore, liberation characteristics of the copper minerals and guidance for development of efficient and environmentally viable crushing/grinding circuits.