Energy-efficient pyrometallurgical process for treating Li-ion batteries
The present disclosure concerns a 2-step smelting process, for recovering of Ni and Co from batteries and other sources. The process comprises the steps of: defining an oxidizing level Ox, and a battery-bearing metallurgical charge; oxidizing smelting of the metallurgical charge by injecting an O 2 -bearing gas into the melt to reach the defined oxidizing level Ox; and, reducing smelting of the obtained slag using a heat source and a reducing agent. The process is more energy-efficient than a single-step reducing smelting process and provides for a higher purity alloy and for a cleaner final slag.
1. Process for the recovery of valuable metals from a metallurgical charge comprising slag formers, and Li-ion batteries or their derived products containing Co, Ni, metallic Al, and C, wherein the slag formers comprise one or more of CaO, Al 2 O 3 , and SiO 2 , comprising the steps of:
providing a metallurgical smelting furnace equipped with means for the submerged injection of an O 2 -bearing gas;
defining an oxidizing level Ox characterizing oxidizing smelting conditions according to the formula:
Ox
=
p
CO
2
/
(
p
CO
+
p
CO
2
)
,
wherein 0.1<Ox<1, pCO and pCO 2 are the partial pressures of CO and CO 2 in contact with the melt;
preparing the metallurgical charge comprising a weight fraction Bf of Li-ion batteries or their derived products, according to the formula:
1
>
Bf
>
0.3
/
(
(
1
+
3.5
*
Ox
)
*
C
)
+
2.5
*
Al
)
,
wherein Ox is the oxidizing level, and Al and C are the weight fractions of respectively metallic Al and C in said batteries or their derived products;
oxidizing smelting the metallurgical charge by injecting an O 2 -bearing gas into the melt to reach the defined oxidizing level Ox, thereby obtaining a first alloy with a major part of Ni, and a first slag containing residual Ni and Co;
liquid/liquid separation of the first alloy from the first slag; and
reducing smelting of the first slag using a heat source and a reducing agent, maintaining a reduction potential ensuring the reduction of Co and Ni, thereby producing a second alloy, and a second slag containing less than 1% by weight of Ni.
2. Process for the recovery of valuable metals from a metallurgical charge comprising slag formers, wherein the slag formers comprise one or more of CaO, Al 2 O 3 and SiO 2 , and Li-ion batteries or their derived products containing Co, Ni, metallic Al, and C, comprising the steps of:
providing a metallurgical smelting furnace equipped with means for the submerged injection of an O 2 -bearing gas;
preparing the metallurgical charge using a weight fraction Bf of Li-ion batteries or their derived products in the metallurgical charge;
defining an oxidizing level Ox characterizing oxidizing smelting conditions according to the formula:
Ox
=
p
CO
2
/
(
p
CO
+
p
CO
2
)
>
(
(
(
0.3
/
Bf
-
2.5
*
Al
)
/
C
)
-
1
)
/
3
.
5
,
wherein 0.1<Ox<1, pCO and pCO 2 are the partial pressures of CO and CO 2 in contact with the melt, and Al and C are the weight fractions of respectively metallic Al and C in said batteries or their derived products;
oxidizing smelting the metallurgical charge by injecting an O 2 -bearing gas into the melt to reach the defined oxidizing level Ox, thereby obtaining a first alloy with a major part of Ni, and a first slag containing residual Ni and Co;
liquid/liquid separation of the first alloy from the first slag; and,
reducing smelting of the first slag using a heat source and a reducing agent, maintaining a reduction potential ensuring the reduction of Co and Ni, thereby producing a second alloy, and a second slag containing less than 1% by weight of Ni.
3. Process according to claim 1 , wherein the step of oxidizing smelting is autogenous.
4. Process according to claim 1 , wherein the first slag is maintained in the liquid state between the steps of liquid/liquid separation and the step of reducing smelting.
5. Process according to claim 1 , wherein the O 2 -bearing gas is enriched air or pure O 2.
6. Process according to claim 1 , wherein Ox<0.98.
7. Process according to claim 1 , wherein said slag formers comprise, by weight, up to 50% CaO, up to 55% Al 2 O 3 , and up to 65% SiO 2 .
8. Process according to claim 1 , further comprising a step of transferring the separated first slag to a second furnace suitable for performing a step of reducing smelting, thereby obtaining a second Ni and Co-bearing alloy, and a depleted second slag.
9. Process according to claim 8 , wherein said second furnace is an electric furnace.
10. Process according to claim 3 , further comprising a step of liquid/liquid separation of the second alloy from the second slag.
11. Process according to claim 10 , further comprising a step of recirculating the separated second alloy to the step of autogenous smelting.
12. Process according to claim 1 , further comprising the steps of:
atomizing the first alloy; and,
dissolving the atomized alloy in acidic conditions, thereby obtaining a metal-bearing solution suitable for further hydrometallurgical refining.