Hexavalent chromium free etch manganese recovery system
Methods for recovering manganese etchant solutions are provided wherein a process solution used to rinse or neutralize a nonconductive substrate after etching the substrate is collected and evaporated to provide a concentrated process solution that is fed back into the manganese etchant solution or acid rinse.
1. A method for recovering manganese etchant solution, the method comprising:
etching a nonconductive substrate with a manganese etchant solution;
neutralizing with a neutralizer the nonconductive substrate after etching the substrate with the manganese etchant solution, wherein the neutralizer comprises a process solution comprising an acid and an oxidizer;
removing from the neutralizer at least a portion of the process solution to an evaporator assembly;
evaporating the process solution in the evaporator assembly to remove water from the process solution to form a concentrated process solution; and
adding the concentrated process solution to the manganese etchant solution or an acid rinse.
2. The method according to claim 1 , wherein the concentrated process solution is concentrated to greater than or equal to about 2 g/L Mn.
3. The method according to claim 1 , wherein the evaporator assembly further comprises an atmospheric evaporator or vacuum evaporator.
4. The method according to claim 1 , wherein the process solution comprises a source of manganese ions.
5. The method of claim 1 , wherein manganese etchant solution comprises Mn(VII) ions.
6. The method of claim 1 , wherein the nonconductive substrate comprises at least one of a plastic or a resin.
7. The method of claim 1 , further comprising pre-etching the nonconductive substrate before etching the nonconductive substrate.
8. The method of claim 1 , further comprising, after neutralizing the nonconductive substrate, exposing the nonconductive substrate to an activator that comprises palladium, platinum, iridium, rhodium, or mixtures thereof.
9. The method of claim 1 , further comprising rinsing the nonconductive substrate in an acid based rinsate.
10. The method according to claim 1 , wherein the evaporator assembly further comprises an evaporating processing tank.
11. The method according to claim 10 , wherein the evaporating processing tank is operated under temperature control and with controlled air treatment.
12. The method according to claim 11 , wherein the controlled air treatment is at a flowrate from about 1880 lb/hr to about 2090 lb/hr.
13. The method according to claim 11 , wherein the temperature is from about 155° F. to about 180° F.
14. The method according to claim 13 , wherein the controlled air treatment is at a flowrate from about 1880 lb/hr to about 2090 lb/hr.
15. A method for recovering manganese etchant solution, the method comprising:
etching a nonconductive substrate with a manganese etchant solution;
rinsing the nonconductive substrate in an acid based rinsate;
neutralizing with a neutralizer the nonconductive substrate after etching the substrate with the manganese etchant solution, wherein the neutralizer comprises a process solution comprising an acid and an oxidizer, wherein the neutralizing results in a used process solution comprising manganese ions;
concentrating at least a portion of the used process solution to a manganese ion concentration similar to the manganese etchant solution; and
feeding the concentrated used process solution into the manganese etchant solution or an acid rinse.
16. The method according to claim 15 , wherein the concentrated used process solution is concentrated to greater than or equal to about 2 g/L Mn.
17. The method according to claim 15 , wherein the process solution comprises manganese ions.
18. The method according to claim 15 , wherein the process solution comprises a source of manganese ions.
19. The method according to claim 15 , wherein at least a portion of the used process solution is transferred into an evaporating processing tank for concentrating the process solution.
20. The method according to claim 19 , wherein the evaporating processing tank is part of an evaporator assembly that further comprises an atmospheric evaporator or vacuum evaporator.
21. The method according to claim 19 , wherein the evaporating processing tank is operated under temperature control at a constant temperature and with controlled air treatment.
22. The method according to claim 21 , wherein the controlled air treatment is at a flowrate from about 1880 lb/hr to about 2090 lb/hr.
23. The method according to claim 21 , wherein the constant temperature is from about 155° F. to about 180° F.
24. The method according to claim 23 , wherein the controlled air treatment is at a flowrate from about 1880 lb/hr to about 2090 lb/hr.