The texture of particles within a flotation cell play a pivotal role in both mineral recovery, and the grade, in the flotation concentrate. Theoretical curves can be generated based on particle mineralogy and texture to indicate the maximum grade-recovery possible for a given feed ore. Comparing this ‘theoretical’ curve to actual grade recovery will provide insight in to the efficiency of the flotation circuit. Inevitably the ‘actual’ curve will plot below the ‘theoretical’; the question is how far below and can that gap be reduced (Figure 1)?
During day-to-day plant operation, deviation of the actual grade/recovery curve from this theoretical curve can be considered to be the result of either a change in the feed texture and mineralogy, or less than optimal operating conditions. A comprehensive understanding of the controls on this will feed decision-making and reduce operational risk. MinAssist has therefore added the Flotation Health Check to its suite of off-the-shelf process mineralogy studies; making it quick, simple and cost effective to use the theoretical grade recovery to help identify potential circuit optimisation.
Figure 1. (A) Ore texture defines the theoretical grade recovery curve. Particle images are used to show how high target mineral recovery will typically also mean recovery of gangue, reducing the grade. (B) If actual grade/recovery is less than the theoretical, then operational conditions may be changed to improve this (1). If grade/recovery above the theoretical curve is targeted, then the texture of the feed will need to change (2). Developed in conjunction with Professor Dee Bradshaw of JKMRC.
A fundamental limit is set by this theoretical grade-recovery curve; no amount of changes to plant conditions (reagents, pH, acid strength, time etc) will improve the grade-recovery beyond this curve due to the physical limitation set by the texture of the feed ore (and in particular liberation and surface area). To improve the potential grade-recovery, changes need to be made to the feed.
The Process Mineralogy Today blog post of 26th October 2009 presents an example of how a theoretical grade-recovery curve can be generated using a copper flotation circuit by way of example:
At MinAssist we often see sites where the project metallurgist is expected to manage improvement programs for all stages of the circuit, along with keeping the process running and becomes overwhelmed. We are therefore working on developing a series of pre-defined Circuit Health Checks that a busy project metallurgist can select straight ‘off the shelf’ from MinAssist, run with a minimum of hassle, and gain some potential quick benefits. Simply select the most applicable Health Check Option, collect the relevant sample and MinAssist will do the rest. This suite of programs is focused on bringing cost savings, recovery improvements and general risk reduction through improved understanding of ore types.
If you feel that there is potential for improving the grade and recovery in the flotation concentrate, then we encourage you to have a look at the MinAssist Flotation Health Check and get in touch with us.
If you would like more information on this program or other process mineralogical services that MinAssist can provide then feel free to contact us anytime for a discussion.