Oxide Leaching Plant

Since the Zinc Plant and the Lead Smelter are on the same site there are processing opportunities to optimize the recovery of lead and zinc and other minor elements contained in the concentrates. As a result, the Oxide Leaching Plant has developed into a treatment plant for recycled and secondary materials which contribute about 10% of the produced zinc.

Zinc oxide fume from the Lead Smelter is the primary feed to this plant. Fume from the slag fuming furnace is treated with sodium carbonate to remove chlorine and fluorine before being used in the zinc circuit. A combined feed of dehalogenated fume and secondary residues is leached with return acid in air agitated pachuca tanks. After this first leach, the slurry is settled to remove a lead oxide residue which is pumped to the Lead Smelter and the clear solution is passed on to the second leach. In the second leach, the slurry is partially neutralized with direct fume addition and ferric iron to precipitate germanium, indium, arsenic and antimony. This precipitate is the feed for the Germanium Recovery Plant.

In the Oxide Leaching Plant's thickener tanks, residues are separated from zinc electrolyte solution.