Characterization and Processing of Residues …
443
The testwork was performed in a standard Denver D12 flotation machine. As the
flotation cell is self-aerated, the rotational speed of the rotor was adjusted so that
the superficial gas velocity in the laboratory cell is comparable to industrial scale
flotation machines. The chemical grades of Pb, Zn, Cu, Fe, and Ag were analysed
by means of atomic absorption spectroscopy (AAS).
Flotation—Results
First tests on a jarosite, trying to separate the jarosite mineral itself from the rest,
failed. Lead seems to be evenly distributed over the different phases, and especially,
the jarosite mineral seems to host lead, e.g. in form of plumbojarosite. Figure 5
shows how the lead recovery follows the weight recovery to the concentrate, and
what finally makes a separation impossible.
Similar results were achieved for silver, while copper and zinc showed a certain
but still inefficient concentration. Materials from other dumps gave slightly better
results, maybe because they host less lead and other metals in the jarosite mineral.
However, concentration was low and needs to be greatly improved, if possible, before
the procedure can be considered as successful.
In case gangue material is present in higher extent, what might be caused by
a mixture with leaching residue, or if gypsum is high, the residue shows a good
potential to be concentrated by separating such compounds. Flotation tests with such
materials allowed especially the concentration of lead, silver, and copper. Zinc was
also concentrated but less successful compared to the other metals.
Figure 6 illustrates the results for one zinc smelter residue that contained around
4% zinc, 7.5% lead, 0.7% copper, and 250 ppm silver before flotation.
From Fig. 6 it can be seen that around 85% of lead, silver, and copper were collected in the concentrate, which amount was 58% of the overall mass. As mentioned,
Fig. 5 Summary of the lead recovery achieved with different reagent regimes and parameter settings
443
The testwork was performed in a standard Denver D12 flotation machine. As the
flotation cell is self-aerated, the rotational speed of the rotor was adjusted so that
the superficial gas velocity in the laboratory cell is comparable to industrial scale
flotation machines. The chemical grades of Pb, Zn, Cu, Fe, and Ag were analysed
by means of atomic absorption spectroscopy (AAS).
Flotation—Results
First tests on a jarosite, trying to separate the jarosite mineral itself from the rest,
failed. Lead seems to be evenly distributed over the different phases, and especially,
the jarosite mineral seems to host lead, e.g. in form of plumbojarosite. Figure 5
shows how the lead recovery follows the weight recovery to the concentrate, and
what finally makes a separation impossible.
Similar results were achieved for silver, while copper and zinc showed a certain
but still inefficient concentration. Materials from other dumps gave slightly better
results, maybe because they host less lead and other metals in the jarosite mineral.
However, concentration was low and needs to be greatly improved, if possible, before
the procedure can be considered as successful.
In case gangue material is present in higher extent, what might be caused by
a mixture with leaching residue, or if gypsum is high, the residue shows a good
potential to be concentrated by separating such compounds. Flotation tests with such
materials allowed especially the concentration of lead, silver, and copper. Zinc was
also concentrated but less successful compared to the other metals.
Figure 6 illustrates the results for one zinc smelter residue that contained around
4% zinc, 7.5% lead, 0.7% copper, and 250 ppm silver before flotation.
From Fig. 6 it can be seen that around 85% of lead, silver, and copper were collected in the concentrate, which amount was 58% of the overall mass. As mentioned,
Fig. 5 Summary of the lead recovery achieved with different reagent regimes and parameter settings