XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3453
In the conditioning tanks, carboxylic acid is added to
help flotation of the fluorite. To neutralize the acid, soda
ash is added to bring the slurry pH back to the 7.7 pH
range. Starch is also added to help separate out the silica.
Finally, the tannin Quebracho (from the South American
“axe-breaker” hardwood tree) is added to help separate the
carbonates and allow ease of flotation recovery of the flu-
orite. This mineral mix is then allowed to condition for
approximately one hour before being pumped to the 3-tier
flotation process.
In the flotation process, the mixture is aggressively agi-
tated both mechanically as well as by aeration to create suit-
able froth production, and the valuable fluorite recovered
in the tradition froth sweeping process.
This fluorite-bearing liquid is run over a vacuum belt
filter to dewater, and the recovered fluorite at 97% pure is
then bagged for sale. The recovered depleted liquid is sent
to the centralized wastewater collection point (Figure 5).
All other waste from the flotation process (included
silica &carbonates) is also directed to the smallish collector
tank on the western side of the plant, from which it usually
pumped to the tailings dam.
For the period of the pilot trial, the product from this
collector tank is the feed material for the decanter centri-
fuge. Some tramp stones (mostly sized +3–10mm) in this
main collector tank still found their way into the feed
pump and the centrifuge. Normally, a mesh screen would
be installed to remove anything over 3mm, but as it was
not possible to stop the process plant to weld in this screen
in place during the trial period, these stones were accepted
as a hazard.
Undesirable feed size or not, the test results did not
show any significant negative impact from these tramp
stones, nor was any vibration detected in the centrifuge as
it processed this oversize feed.
Solids in this feed slurry typically range around 11%–
16%, but during the trials it was apparent that this could
regularly be on the lower limit – partly due to the recir-
culation of the centrifuge’s centrate output back to the
waste collector tank. Visually, the silica in this feedstock
Figure 4.
Figure 5.
In the conditioning tanks, carboxylic acid is added to
help flotation of the fluorite. To neutralize the acid, soda
ash is added to bring the slurry pH back to the 7.7 pH
range. Starch is also added to help separate out the silica.
Finally, the tannin Quebracho (from the South American
“axe-breaker” hardwood tree) is added to help separate the
carbonates and allow ease of flotation recovery of the flu-
orite. This mineral mix is then allowed to condition for
approximately one hour before being pumped to the 3-tier
flotation process.
In the flotation process, the mixture is aggressively agi-
tated both mechanically as well as by aeration to create suit-
able froth production, and the valuable fluorite recovered
in the tradition froth sweeping process.
This fluorite-bearing liquid is run over a vacuum belt
filter to dewater, and the recovered fluorite at 97% pure is
then bagged for sale. The recovered depleted liquid is sent
to the centralized wastewater collection point (Figure 5).
All other waste from the flotation process (included
silica &carbonates) is also directed to the smallish collector
tank on the western side of the plant, from which it usually
pumped to the tailings dam.
For the period of the pilot trial, the product from this
collector tank is the feed material for the decanter centri-
fuge. Some tramp stones (mostly sized +3–10mm) in this
main collector tank still found their way into the feed
pump and the centrifuge. Normally, a mesh screen would
be installed to remove anything over 3mm, but as it was
not possible to stop the process plant to weld in this screen
in place during the trial period, these stones were accepted
as a hazard.
Undesirable feed size or not, the test results did not
show any significant negative impact from these tramp
stones, nor was any vibration detected in the centrifuge as
it processed this oversize feed.
Solids in this feed slurry typically range around 11%–
16%, but during the trials it was apparent that this could
regularly be on the lower limit – partly due to the recir-
culation of the centrifuge’s centrate output back to the
waste collector tank. Visually, the silica in this feedstock
Figure 4.
Figure 5.