There are three types of staged flotation processes: first-stage tailings regrinding, first-stage low-grade concentrate regrinding (rough concentrate), and first-stage middlings regrinding.
Figure 6-5 shows a first-stage tailings regrinding and re-flotation staged flotation process, suitable for ores with heterogeneous disseminated valuable minerals. After the first-stage grinding (rough grinding), some of the coarsely disseminated valuable minerals can be liberated and float to the surface in the first stage as qualified concentrate. After regrinding, the finely disseminated portions of the tailings are separated, and then the concentrate and waste tailings are obtained through a second-stage flotation process.
Figure 6-6 shows a staged flotation process where the first stage yields low-grade concentrate and waste tailings, which are then regrinded before the second-stage flotation. This is suitable for ores with aggregated disseminated valuable minerals.
Figure 6-7 shows the qualified concentrate and waste tailings obtained from the first stage. The middlings containing more intergrowths are regrinded and then subjected to the second stage of flotation. This method is suitable for processing ores with fine-grained disseminated useful minerals.