Glencore Zinc Projects

​An Albion Process™ plant was constructed at the San Juan de Neiva zinc refinery in July 2010. The San Juan de Neiva zinc refinery is the world's largest zinc refinery, with an annual production of over 550,000 tonnes of zinc. 

The San Juan de Neiva Albion Process™ plant has a throughput of 8000 tpa of concentrate, ground to a size of 80% passing 7 microns. The plant produces 4000 tonnes per annum of cathode zinc from the concentrate, at a recovery of 98.6% w/w. The leach is an oxygenated sulphuric acid leach, using spent electrolyte from the electrowinning plant. 

​The finely ground McArthur River Lead-zinc concentrate is first re-slurried in spent electrolyte from the electrowinning cellhouse, and the slurry pumped to the oxidative leaching circuit. The oxidative leach consists of 280 m3 Albion Leach Reactors, with a live height of 9.5 m and a diameter of 6 m. 

Concentrate slurry and spent electrolyte are transferred to the Albion Leach Reactors along with residue slurry from the Neutral Leach circuit, which introduces ferrite residues from the Neutral Leach into the Albion Leach circuit for oxidation. The oxidative leach circuit is also used to recover zinc from ferrite phases that do not leach in the Neutral Leach circuit. The high operating temperature of the leach circuit results in rapid breakdown of the ferrites. This allows the Albion Process™ leach circuit to act as a traditional Hot Acid Leach for the recovery of zinc from ferrite residues. 

Oxygen is injected into the base of the reactors using 8 HyperSparge™ supersonic oxygen injection lances, and the slurry is agitated by a centrally mounted dual hydrofoil impeller. Residence time in the oxidative leach circuit is approximately 28 hours. 

The oxidised slurry from the oxidative leach plant is then processed to recover both the elemental sulphur and the lead as separate products. The slurry is first thickened, and the thickener underflow then treated to recover elemental sulphur in a series of 10 m3 flotation cells. The flotation concentrate, containing up to 70% w/w elemental sulphur is filtered in a plate and frame filter assembly, and the filtrate returned to the thickener circuit. The sulphur concentrate is transferred to the roasting plant and burnt to produce sulphuric acid. 

The flotation circuit tailings are filtered in a horizontal belt filter, with the high grade residue then sold to secondary lead recyclers. The filtrate and wash from the horizontal belt filter is returned to the thickener. Thickener overflow reports to the existing jarosite precipitation circuit for iron removal ahead of the zinc dust precipitation circuit and the cellhouse.