| 摘要 |
1. A method of purifying an acid leaching solution obtained when working-up liydrometallurgically material that contains valuable metals, said solution also containing Fe<3+> and Fe<2+> and possibly also arsenic in solution in addition to said valuable metals, characterised by adding a pH-elevating agent to the leaching solution such as to precipitate the major part of its Fe<3+>-content and the arsenic present in a first stage; separating the precipitate formed in the first stage from the solution and removing said precipitate from the process; adding a further pH-elevating agent to the solution in a second stage such as to oxidise Fe<2+> and precipitate the resulting Fe<3+> and possibly any remaining arsenic; separating the resultant precipitate and any residual solid pH-elevating agent from the solution and returning the same in the process to more acid conditions; and thereafter winning the valuable metal content of the thus purified solution in a manner known per se. 2. A method according to Claim 1, characterised by raising the pH to a value within the range of 2.2-2.8 in the first precipitation stage. 3. A method according to Claim 1, characterised by raising the pH to a value in the range of 3.0-4.5 in the second precipitation stage. 4. A method according to any one of Claims 1-3, characterised in that oxidation is achieved in the second precipitation stage by injecting air into the solution. 5. A method according to any one of Claims 1-4, characterised by using lime or limestone as the pH-elevating agent. 6. A method according to any one of Claims 1-5, characterised by returning solid material separated from the second precipitation stage to the first precipitation stage. 7. A method according to any one of Claims 1-6, characterised by returning some of the solid material separated from each precipitation stage within respective stages as a nucleating agent. |
