Method for recovering metals from electronic waste containing plastics materials

1. A method for treating materials containing a mixture of plastic and metal materials, said method comprising:

shredding the materials to be processed;

performing pyrolysis of the shredded material;

a first magnetic separation performed on the pyrolyzed materials, providing a ferrous metal fraction and, secondly, non-ferrous residues;

a second magnetic separation performed on the non-ferrous residues, providing, on the one hand, a non-ferrous metal fraction and, on the other hand, non-magnetic residues containing precious metals, and

a step of combustion of the gasses from pyrolysis,

wherein the step of combustion of the gases from pyrolysis is followed by a step of neutralizing the gas with sodium bicarbonate.

2. The method according to claim 1 , wherein the material is electronic waste, preferably used electronic circuit boards.

3. The method according to one of claim 1 or 2 , wherein the shredding is performed down to a screen passage size D max not exceeding 50 mm, preferably between 20 and 30 mm.

4. The method according to one of claims 1 - 3 , wherein the pyrolysis is performed at a temperature between 300 and 600° C. and/or with an air factor between 0.7 and 0.98.

5. The method according to one of claims 1 - 4 , wherein the first magnetic separation is effected by a magnet or electromagnet.

6. The method according to one of claims 1 - 5 , wherein the second magnetic separation is performed using an eddy current separator.

7. The method according to one of claims 1 - 6 , wherein the precious metals contained in the non-magnetic residues include gold, silver, platinum, palladium, rhodium, ruthenium, iridium and/or osmium.

8. The method according to one of claim 1 - 6 or 7 , wherein:

the ferrous metal fraction comprises iron and/or derivatives of iron, and possibly gold and/or

the non-ferrous metal fraction comprises aluminum and/or zinc.

9. The method according to one of claim 1 - 6 or 7 - 8 , wherein the non-magnetic residues include copper, lead, tin, glass fibers, carbon.

10. The method according to one of claim 1 - 6 or 7 - 9 , wherein the ferrous metal fraction is combined with non-magnetic residues after the second magnetic separation.

11. The method according to one of claim 1 - 6 or 7 - 10 , comprising a further stage of processing the non-magnetic residues to recover the copper content in the non-magnetic residue and/or recover precious metals contained in the non-magnetic residue in particular selected from gold, silver, lead, tin, platinum, palladium, rhodium, ruthenium, iridium and/or osmium.

12. A plant for treating a material containing a mixture of plastic and metal materials, comprising successively:

shredding means;

a pyrolysis facility;

a flow line for collecting pyrolysis gasses supplying a combustion chamber;

at the exit from the combustion chamber, a contact chamber fed by a supply of activated carbon and a supply of sodium bicarbonate;

a primary magnetic separator; and

a secondary magnetic separator.

13. The plant according to claim 12 , wherein the shredding means are adapted to perform shredding down to a screen passage size D max not exceeding 50 mm, preferably between 20 and 30 mm.

14. The plant according to one of claim 12 or 13 , wherein the primary magnetic separator comprises a magnet or electromagnet placed above a conveyor belt.

15. The plant according to one of claims 12 to 14 , wherein the secondary magnetic separator comprises a separator using eddy currents.