Pyrometallurgical process for recovering nickel, manganese, and cobalt
A 2-step high temperature process for recovering Ni, Co, and Mn from various sources comprises preparing a metallurgical charge comprising materials containing Ni, Co, and Mn, and Si, Al, Ca and Mg as slag formers; smelting the charge with slag formers in first reducing conditions, thereby obtaining a Ni—Co alloy comprising a major part of at least one of Co and Ni, with Si<0.1%, and a first slag comprising the major part of the Mn; separation of the first slag from the alloy; and, smelting the first slag in second reducing conditions, more reducing than said first reducing conditions, thereby obtaining a Si—Mn alloy comprising the major part of the Mn, with Si>10%, and a second slag. A Ni—Co alloy is produced, and a Si—Mn alloy is produced. The second slag is essentially free of heavy metals and therefore suitable for reuse.
1. Process for the production of Si—Mn alloy from materials containing Ni, Mn and Co, comprising the steps:
a) preparing a metallurgical charge comprising said materials, and Si, Al, Ca, and Mg as slag formers;
b) smelting the charge in first reducing conditions, thereby obtaining a Ni-Co alloy and a first slag, wherein the Ni-Co alloy comprises a major part of at least one of Co and Ni and has a Si content <0.1 wt %, and wherein the first slag comprises a major part of the Mn;
c) separation of the first slag from the Ni-Co alloy; and
d) smelting the first slag in second reducing conditions, more reducing than said first reducing conditions, thereby obtaining a Si-Mn alloy and a second slag, wherein the Si-Mn alloy comprises a major part of the Mn and has a Si content >10 wt %.
2. Process according to claim 1 , wherein the first slag has a composition according to:
0.25<SiO 2 /Al 2 O 3 <2.5;
0.5<SiO 2 /CaO<2.5;
MnO>2.5 wt %;
MgO>5 wt %; and,
Co+Ni>0.1 wt %.
3. Process according to claim 1 , further comprising the step of adding the Si—Mn alloy to an Fe-based molten phase, thereby obtaining Si—Mn steel.