Pre-Processing to Increase the Capacity of SAG Mill Circuits—Case Study

Abstract

This paper describes the adopted approach for increasing the capacity of an existing industrial grinding circuit by adapting the respective configuration to process the ore from a new mine. Accordingly, due to Sossego mine exhaustion, Vale S. A. decided to use the existing industrial facilities and infrastructure for processing the Cristalino ore deposit located in Para state, within the Brazilian Amazon. Considering the higher hardness of Cristalino ore compared to Sossego ore, a reduction in capacity in the existing SAG grinding circuit was anticipated. A comprehensive grinding pilot plant campaign was conducted with a characterization program including 98 Cristalino ore samples, as described throughout this paper. Sossego grinding circuit was also surveyed for mathematical modeling and simulations to assess such an estimative further. The mathematical model calibration for setting different circuit configurations and operating conditions to enhance the circuit’s capacity was based on the combination of pilot plant results and ore characterization. Simulations indicated that a capacity increase of 12% would be achieved in the existing grinding circuit by further crushing 35% of SAG mill fresh feed. Such figures would represent yearly additions of 8.3 kt in copper and 250 kg in gold productions.