As for copper–zinc ores, some of the lead–zinc ores are treated using bulk flotation followed by lead–zinc separation. This method is basically used in cases where zinc is preactivated in situ or during grinding. It is also used for the treatment of ores containing soluble cations and ores with acidic natural pH.
As lead mining declined in Mineral Point, zinc mining and smelting became important new industries. Zinc ore was discovered with increasing frequency near the bottoms of old lead mines. The Mineral Point Zinc Company was founded in 1882, and by 1891 it was operating the largest zinc oxide works in the United States at Mineral Point.