Effect of temperature variation on the copper slag flotation at Aurubis-Bulgaria

A laboratory-scale study investigating the effect of pulp temperature on copper recovery during slag reprocessing by flotation operated at the Aurubis-Pirdop copper smelter in Bulgaria was conducted.

Temperature variations in the range of 15 to 35 °C have been investigated to follow up grade and recovery of copper and iron during rougher and scavenger stages without modifying the reagent suite as used at the plant. In parallel to the laboratory tests, plant survey has been realized to trace pulp physicochemical parameters (DOD, Eh, pH, conductivity). The data collected during the plant survey have been compared to the one registered during the laboratory tests.

Kinetics and grade-recovery curves for the Cu-bearing phases (metallic and sulphide Cu) and iron have been drawn as function of the various temperatures. Automated mineralogy analysis has been realized on copper, iron, and gangue minerals (fayalite, quartz) to find out the liberation degree of the copper bearing phases, their morphology and composition.

Ultimately, it has been established that elevated temperatures (35 °C) favor both higher grade and recovery of Cu-phases when compared to the rest temperature conditions being tested (15, 20, 25 °C). The reasons for occasional copper losses in the tailings during the winter periods are discussed on that basis.