Process for the recovery of metals from polymetallic nodules
AssigneeUmicore AG & Co. KG
InventorsMichel Daniels, Jean Scoyer, Michael Baltes, Margot Neven, Jan Leyssen
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Abstract
The present disclosure concerns a process for the recovery of valuable metals from polymetallic nodules. A two-stage process using SO2 in an acidic aqueous media is disclosed. In a first step, performed in mildly acidic conditions, Mn, Ni, and Co are dissolved; in a second, more acidic step, Cu is dissolved. Under these conditions, the leachate of the first step contains most of the Mn, Ni, and Co, while being nearly Cu-free. The Ni and Co are precipitated as sulfides; the Mn can be recovered as sulfate by crystallization. Cu, which is leached in the second step, is selectively precipitated, also as sulfide.
Claims6
Process for the recovery of the metals Mn, Ni, Co, and Cu from polymetallic nodules, comprising the steps of leaching said metals using an SO2-bearing gas as leaching agent in acidic aqueous conditions, wherein the leaching is performed according to a two-stage process comprising the steps of:
- a first leaching (L1), wherein a major part of the Mn, Ni, and Co is dissolved by contacting the nodules with a first quantity of SO2-bearing gas in a first acidic aqueous solution of sulfuric acid at a pH of 2 to 4, thereby producing a first leach solution and a first leach residue, which are separated;
- and,
- a second leaching (L2), wherein a major part of the Cu is dissolved by contacting the first leach residue with a second quantity of SO2-bearing gas in a second acidic aqueous solution of sulfuric acid at a pH of less than 1.5, thereby producing a second leach solution and a second residue, which are separated,
- wherein the process further comprises:
- crystallization of the Mn from the Mn-bearing phase by heating and/or by evaporation of water, thereby obtaining a Mn-bearing solid, which is separated;
- pyrolysis of the Mn-bearing solid by heating at a temperature of more than 850° C. thereby forming Mn oxide and an SO2-bearing gas, which is separated;
- and
- recirculation of the SO2-bearing gas to either one or both leaching steps (L1, L2) for use as leaching agent,
- wherein an excess of SO2-bearing gas is fed as leaching agent to the second leaching step (L2), thereby obtaining a stream of unreacted SO2, for use as leaching agent in the first leaching (L1) step.
Dependencies are inferred from the claim text.