HEMATITE PRECIPITATION

摘要

A hydrometallurgical method for precipitating iron in the form of hematite from leach solutions containing nickel, cobalt and iron, characterised by the steps of: i) pre-neutralising (12) the leach solution by the addition of a neutralising agent (14); ii) oxidising ferrous sulphate to ferric sulphate (16) by sparging air or oxygen into the solution resulting from step (i) at an elevated temperature; iii) adjusting the free acid and pH of the solution resulting from step (ii) to levels suitable for hematite precipitation; iv) adding hematite seed (22) to the solution resulting from step (iii) and maintaining the solution in these conditions for a residence time such that substantially complete conversion of ferric sulphate to hematite precipitate is achieved; v) filtering or thickening (24) the solution from step (iv) to remove the hematite precipitate; vi) recycling a portion of the hematite precipitate of step (v) to step (iv) as the hematite seed; and vii) recovering nickel and cobalt (26) from the filtrate solution.