Cleaning Flotation And Regrinding Circuits Characterization

The cleaning circuit operation and its effect on the plant metallurgical performance, was characterized at Los Pelambres concentrator, Chile. Experimental data from columns, scavenger and regrinding stages was evaluated. Each stage was characterized by size fractions, and the interaction between stages (columns, scavenger, regrinding) as well as the effect that circulating loads had. The approach for describing the flotation equipment operation (cells and columns) considered the collection and froth zones separately. This methodology allows for the identification of the impact that particle size distribution has on the actual collection and froth transport processes, independently. In this way the effect of regrinding on flotation recovery and grade can be related to the corresponding operating variables, e.g. pulp flowrate, air flowrate, pulp level and pulp density, among others. The effect of gangue entrainment was considered using an empirical dimensionless correlation. The interaction between the circulating load and the overall performance of cleaning circuit was evaluated. The circulating load was defined as the ratio between the solid flowrate of scavenger concentrate over rougher concentrate. It was found that the overall cleaning flotation circuit (column-scavenger) can operate at a relatively high and constant recovery for a wide range of mineral treatment. This is possible when the scavenger has the capacity for compensating the decrease in column recovery at larger circulating loads. Under the condition of high overall cleaning recovery, the rougher stage closely represents the plant recovery. However, at large mineral treatment conditions, the design characteristics (e.g. concentrate transport channel capacity and transfer boxes) as well as instrumentation, control facilities and operation, became bottle-necked. A simulator was developed using empirical models for each stage (column, scavenger and regrinding) in order to evaluate proper operational strategies for cleaning flotation circuits Keywords: flotation, cleaning, regrinding, Vertimill, simulation.