In the flotation of complex sulfide ores, the separation of copper and zinc is relatively difficult, mainly due to two reasons:
(1) Copper and zinc minerals are often densely coexisting. In some deposits (such as high-temperature deposits), chalcopyrite often exists as fine-grained (sometimes below 5 μm) disseminated sphalerite, making it difficult to liberate individual minerals. There is currently no good solution to this problem of separation caused by the genesis of the deposit.
(2) If the surface of sphalerite is activated by copper ions, its floatability becomes similar to that of copper minerals, making separation difficult. To improve the separation of copper and zinc, the following measures can be taken:
(1) Precipitate copper ions in the slurry to prevent their activation of sphalerite. Sodium sulfide and cation exchange resin can be used for treatment. The former can precipitate copper ions in the slurry, preventing copper ions from activating sphalerite. The latter, added to a ball mill, can adsorb copper ions in the slurry, achieving the purpose of preventing copper ions from activating sphalerite. (2) Sodium cyanide or sulfuric acid can be used as deactivating agents to remove copper ions adsorbed on the surface of sphalerite.
(3) De-refining of the mixed concentrate. De-refining is performed on the copper-zinc mixed concentrate before separation to remove the collector from the surface of the mineral particles, thus facilitating separation. Activated carbon or sodium sulfide can be used as de-refining agents.