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D. Dreisinger et al.
• Lead melting, casting and load-out
• Utilities and reagents
• Power station, heat recovery, and steam generation.
A brief description of these areas follows.
Feed Preparation, Leaching, and Solid/Liquid Separation
Concentrate from the existing concentrator is filtered and washed on the existing VPA
filter press using demineralized water. The filter cake is then dried in a Holoflite
®
dryer (to drive off flotation reagents), repulped utilizing MSA leach liquor and stored
in the hydrometallurgical facility feed storage tank (18 h capacity) from where it fed
to the MSA leach facility.
• MSA leach;
• DeS leach; and
• MSA re-leach.
In the MSA leach, the slurry is mixed with recycled spent electrolyte. The process
evolves carbon dioxide, which is extracted through a wet scrubber and vented to
atmosphere. Hydrogen peroxide is also added to facilitate the generation of ferric
methane sulphonate to leach any galena present in the feed. The leach slurry (pH
<0.5) passes through a vacuum degasser for removal of dissolved carbon dioxide
generated during the leaching process. The degassed slurry is then flocculated and
thickened. Thickener U/F (leach Residue) is settled and washed in a six-stage CCD
circuit. The final CCD thickener underflow is pumped to the DeS leach tanks. Solution
overflow (electrolyte) from the first thickener is pumped to the impurity removal and
electrolyte preparation circuit.
In the DES leach, the MSA leach residue is leached with the addition of soda
ash which converts the anglesite to cerussite. Slurry from the DeS leach is pumped
to the existing flotation plant where the lead minerals are recovered by flotation.
The concentrate is washed with demineralized water in a small flotation column and
returned to the MSA releach circuit. The releach operates at 65 °C with ferric iron
regenerated by hydrogen peroxide addition. The MSA leach extracts nearly 90%
of the remaining lead and targets the Galena. The MSA releach discharges into the
MSA leach circuit (Fig. 8).
Impurity Removal and Electrolyte Preparation
The impurity removal process ensures the iron and aluminum levels in the MSA
leach liquor are acceptable in the electrowinning circuit. MSA leach liquor is mixed
with a lime slurry in agitated reactors to precipitate the aluminum and iron. The
discharge from the reactors is thickened and a portion of the underflow is recycled
to assist in seeding the precipitate. Impurity thickener U/F is recycled in part to the
D. Dreisinger et al.
• Lead melting, casting and load-out
• Utilities and reagents
• Power station, heat recovery, and steam generation.
A brief description of these areas follows.
Feed Preparation, Leaching, and Solid/Liquid Separation
Concentrate from the existing concentrator is filtered and washed on the existing VPA
filter press using demineralized water. The filter cake is then dried in a Holoflite
®
dryer (to drive off flotation reagents), repulped utilizing MSA leach liquor and stored
in the hydrometallurgical facility feed storage tank (18 h capacity) from where it fed
to the MSA leach facility.
• MSA leach;
• DeS leach; and
• MSA re-leach.
In the MSA leach, the slurry is mixed with recycled spent electrolyte. The process
evolves carbon dioxide, which is extracted through a wet scrubber and vented to
atmosphere. Hydrogen peroxide is also added to facilitate the generation of ferric
methane sulphonate to leach any galena present in the feed. The leach slurry (pH
<0.5) passes through a vacuum degasser for removal of dissolved carbon dioxide
generated during the leaching process. The degassed slurry is then flocculated and
thickened. Thickener U/F (leach Residue) is settled and washed in a six-stage CCD
circuit. The final CCD thickener underflow is pumped to the DeS leach tanks. Solution
overflow (electrolyte) from the first thickener is pumped to the impurity removal and
electrolyte preparation circuit.
In the DES leach, the MSA leach residue is leached with the addition of soda
ash which converts the anglesite to cerussite. Slurry from the DeS leach is pumped
to the existing flotation plant where the lead minerals are recovered by flotation.
The concentrate is washed with demineralized water in a small flotation column and
returned to the MSA releach circuit. The releach operates at 65 °C with ferric iron
regenerated by hydrogen peroxide addition. The MSA leach extracts nearly 90%
of the remaining lead and targets the Galena. The MSA releach discharges into the
MSA leach circuit (Fig. 8).
Impurity Removal and Electrolyte Preparation
The impurity removal process ensures the iron and aluminum levels in the MSA
leach liquor are acceptable in the electrowinning circuit. MSA leach liquor is mixed
with a lime slurry in agitated reactors to precipitate the aluminum and iron. The
discharge from the reactors is thickened and a portion of the underflow is recycled
to assist in seeding the precipitate. Impurity thickener U/F is recycled in part to the