Abstract
Continuous achievement of optimal flotation cell operation (maximum recovery at a given throughput rate) in a mineral processing facility is extremely challenging, even for the most experienced operations teams. Operators must coordinate air flow, reagent addition, and pull rates in response to both gradual and sudden changes in feed rates and composition. Moreover, they must do so using limited measurement technology that leaves uncertainty about incoming and outgoing composition and flow rates. However, sub-optimal flotation operation resulting in even fractions of a percentage in recovery losses have significant impacts on site-wide economics, and can cost even small-medium mineral processing facilities millions of dollars per year in lost revenue.
Over the past two decades, many model-based advanced control strategies have been proposed and developed to address this pressing problem, but many operations have struggled to achieve meaningful sustainable results in real production environments. In this paper, a novel field-tested method for controlling and continuously optimizing flotation operation will be presented. Key features of this solution include:
- Novel measurement of open-channel flotation pull rates using conventional, accurate and robust measurement technology
- A novel, flexible approach to control of a single bank using a technology known as Integrated Quadratic Control (IQC) that allows metallurgists and operators to guide automation in order to provide optimal coordinated operation that remains stable, even through major upsets to feed supply and grinding operations
- A novel approach to site-wide recovery maximization that coordinates flotation from roughers to cleaners, balancing pull rates against final assay grade requirements
Contents of this paper include an overview of the above methodology along with performance results in both pilot scale and full scale production environments.