Abstract: Biological leaching solution of lowgrade carrollite often contains a high concentrations of iron， a low concentrations of cobalt and a amount of copper when using the biological oxidation method. So the selective separation of copper was carried out before the recovery of cobalt to avoid the loss of cobalt.LIX984N as an extractant was used to selectively separated and extracted copper from the lowgrade carrollite biological leaching solution. The results showed that，when the volume fraction of LIX984N is 25%， ambient temperature 35℃， O/A 1∶1， mixing time 5 min and equilibrium pH 125， the extraction rate of copper is 994%.Under the same condition， the extraction rates of the iron of entrainment and the cobalt was only 403% and 0849% respectively. Loaded organic phase was washed by pure water under O/A 1∶1， the extraction rates of the cobalt and iron of entrainment decreased to 0008% and 0766% respectively. After washing， loaded organic phase was stripped using sulfuric acid solution with concentration of 200g/L.When O/A was 1∶1， after two countercurrent stripping，the copper stripping rate was 9813%.

Key words: lowgrade carrollite, bioleaching, extraction, cooper and cobalt, iron