ABSTRACT Process mineralogy was applied to design the process circuit of magnetite tailings containing copper, lead and zinc from Marcona Iron Ore Mine. Mineralogy parameters, such as mineral composition, occurrence, and grain size distribution of the main minerals, were investigated in detail. The results showed that the main valuable elements including 41.40 wt.% iron, 0.064 wt.% copper, 0.38 wt.% lead, and 0.96 wt.% zinc, were primarily in the occurrence of magnetite, chalcopyrite, galena, and sphalerite, respectively. In addition, complex interlocking relationships were observed among the copper-zinc-lead minerals. Therefore, a fine grinding process was required for mineral liberation, followed by magnetic separation for magnetite collection. Iso-floatability flotation process was further applied to the magnetic tailings, achieving a copper grade of 28.37 wt.% and a recovery of 25.11% in the copper concentrates. Subsequently, zinc and lead grades of 49.04% wt.% and 8.06% wt.% were obtained in the zinc-lead concentrates, with a recovery of 51.72% and 25.21%, respectively. Therefore, this study provides an available separation of copper-zinc-lead minerals from iron tailings at Marcona Iron Ore Mine based on process mineralogy, thereby giving a prior diagnosis strategy to increase the utilization efficiency of iron tailings.