An example of testing the effect of pH on rougher flotation on pit samples and the results are presented. Since this is only an example, it needs reminding that not all ores will respond the same.
Here, rougher flotation is most Selective at a pH of 9.5 as pH levels in the 9 to 10 range yielded 1% to 2% better recoveries. Mineralogy data also supports this and shows between 3% and 10% of the copper is present as low-grade middlings in pyrite, and further supports the benefit of floating middlings pyrite to maximize copper rougher recovery. This is also facilitated by the use of a more selective thionocarbamate collector. There was no significant pH effect on gold recovery.
AN INVESTIGATION OF COPPER RECOVERY FROM A SULPHIDE OXIDE ORE WITH A MIXED COLLECTOR SYSTEM
Copper and Cyanide Recovery in Cyanidation Effluents
Effect of pH on the Recovery and Grade of Base metal flotation