Hi all,
i am interested in learning about your opinion regarding different approaches to reclaim metal from chemical deposition bathes. Those bathes are intended for "electroless" plating. Instead of putting amps to work, the bath composition is slightly instable on purpose and will decompose just on the work piece surface in order to deposit (selectivly) metal. Either by difference in nobility (immersion plating) or when the work piece surface is catalytic active to support decomposition for a reductor specimen, which puts (locallly) charge on the surface that can reduce solubal metal down. Most prominent example would probably be electroless Nickel which is often based on hypophosphite as reductor.
Currently i am looking at a Pd deposition bath with app 2 g/L PGM complexed in solution, some hypophosphite and lead salt as stabilizer. pH about neutral and no other metal present in significant amounts. Processing would need to handle app. 100 L per month.
Possible ways to get the metal out:
1) Plating chemical "out of spec" further on some dummy material. Need heating, agitation, maybe even reductor replenishment... that does not sound smart.
2) Cementing Pd chemically out. Just dumping Cu or Zn powder in and filtrate anything out. Maybe a bit messy, but if the hypophosphite does not bother, a viable solution.
3) Galvanic plating with a simple setup. I just saw at an chinese marketplace a company advertising "reclaim" systems and they named one even for Pd. Pictures showed rotating steel cathode and graphite anodes. Voltage was (in a picture) adjusted to 2.3V. Metal could be scrubbed of the drum-cathode after some runs. Some papers i found talked about very high reclaim rates for Pd from wastewater, but i am not sure what unwanted specimen could form on the anode in this process.
Did i miss any other option? Do you see a flaw in either of those approaches?
Thanks for reading.
i am interested in learning about your opinion regarding different approaches to reclaim metal from chemical deposition bathes. Those bathes are intended for "electroless" plating. Instead of putting amps to work, the bath composition is slightly instable on purpose and will decompose just on the work piece surface in order to deposit (selectivly) metal. Either by difference in nobility (immersion plating) or when the work piece surface is catalytic active to support decomposition for a reductor specimen, which puts (locallly) charge on the surface that can reduce solubal metal down. Most prominent example would probably be electroless Nickel which is often based on hypophosphite as reductor.
Currently i am looking at a Pd deposition bath with app 2 g/L PGM complexed in solution, some hypophosphite and lead salt as stabilizer. pH about neutral and no other metal present in significant amounts. Processing would need to handle app. 100 L per month.
Possible ways to get the metal out:
1) Plating chemical "out of spec" further on some dummy material. Need heating, agitation, maybe even reductor replenishment... that does not sound smart.
2) Cementing Pd chemically out. Just dumping Cu or Zn powder in and filtrate anything out. Maybe a bit messy, but if the hypophosphite does not bother, a viable solution.
3) Galvanic plating with a simple setup. I just saw at an chinese marketplace a company advertising "reclaim" systems and they named one even for Pd. Pictures showed rotating steel cathode and graphite anodes. Voltage was (in a picture) adjusted to 2.3V. Metal could be scrubbed of the drum-cathode after some runs. Some papers i found talked about very high reclaim rates for Pd from wastewater, but i am not sure what unwanted specimen could form on the anode in this process.
Did i miss any other option? Do you see a flaw in either of those approaches?
Thanks for reading.