Designed collectors for selective flotation

Purpose and goal
The aims were to synthesise a new collector with two functional xanthate headgroups to test selectivity for Cu-Ni sulphides in one of Boliden’s ores compared with PAX used today. A method to produce the collector in larger scale (1 kg) were to be developed. Flotation tests with the collector were to be made in lab scale on pure minerals and on selected ores from Boliden’s mine in Kevitsa. The synthesis method was developed and optimised, flotation tests were performed both on pure minerals and on ores from Kevitsa and Kylylahti, and the results were compared with the currently used collector (PAX).

Structure and implementation
Different versions of the collector with different distances between xanthate groups were synthesised in small scale. One version was chosen for larger scale synthesis. NMR was used to control purity, intermediates and end product. Hallimond flotation was used with different collector versions to study differences in recovery for pure sulphide minerals at different pH and collector concentrations. Lab scale tests on the new collector was performed on ores with different composition from Kevitsa and Kylylahti. The results were compared with present flotation protocol as reference.

Results
A method for upscaling collector production was developed and optimised regarding number of steps, max volume, choice of regents and solvents. Unit operations not suitable for upscaling were removed. Flotation tests on pure minerals showed ca 80% recovery for chalcopyrite, galena and pentlandite for all versions of the collector. Sphalerite and pyrrhotite gave less recovery (40% and 25%). Tests on recovery and Cu/Ni selectivity for ores from Kevitsa and Kylylahti showed that the new collector was neither better nor worse than the references.