palladium from nitrate solution

[Research135]

sssshhhh!

 

[kjavanb123]

Hi,

I am dealing with 15 liter of silver (300grams), and palladium (6grams) nitrate solution. I add salt to precipitate silver chloride, filter it, and now for the palladium nitrate solution, based on the information exchanged here, I need to bring the pH to 6, then add SMB to drop Pd as yellow salt? Or does raising pH to that level make the Pd to drop as its hydroxide?

Best regards
Kj

 

[Rougemillenial]

The best suggestion I have for getting the palladium out would be dimethylglyoxime. Unfortunately the chloride drop will only work if the pH is higher than 5. If it's lower than that an equalibrium will form between h3o+, XCl and HCl, X+ spectator ions. The HCL will react with the nitrate to form crude aqua regia and form NOCl which will waste extremely expensive nitrate and possibly inhibit the dropping of the silver instead pushing the reaction towards nitrate and nitrosyl chloride. So the solution would have a significant amount of silver. Not to mention that silver chloride like gold won't drop out of solution at a low pH. The way to go if you can't make or buy DMG would be to raise the pH with a small amount of base, then use a bit of sodium sulfate to drop the lead out. Then you will have a solution that contains palladium, silver nitrate/sulfate, and copper primarily. The silver can then be dropped out with
Sodium chloride to form sodium nitrate and silver chloride. Once that's done, the palladium chloride remaining can be dropped out with copper metal. This leaves sodium nitrate and copper chloride in solution. You can save this to make nitric acid when it's needed thus saving costs. The reason why I would recommend this over a simple chloride drop besides the obvious selectiveness of the precipitation is the higher efficiency of the drop. Raising the pH allows the reaction to go to completion. However it does take longer than adding DMG and then dropping the silver out with copper metal. If you have access to say hydroxylamine monosulfonate sodium salt, MEK, and sodium nitrite I highly suggest you just make DMG. This process just applies to those who cannot easily get or make DMG. I hope this helps. Being an ametuer chemist, I usually have to use stuff at my immediate disposal. Hydrochloric acid from pool supply stores charcoal briquettes as gas scrubbing compound, Home Depot 5 gallon pails to do my reactions in, and enormous camounts of time designing reaction pathways and researching the millions of reactions transition metals and metaloids can do. I have to read the ingredients of common items and find ways to purify it to a point of being useful. However I do this sort of thing on a far larger scale than most refiners would do e-waste recovery on. I processed a few metric tons of material over 3 years. I am left with about 200 or so kilos of concentrates consisting of the PMS, copper, organics and ceramics. I did an assay and figured out that I had around 40oz a ton of precious metals. Though I could be way off due to my furnace breaking halfway through the melt. I managed to get a refund and my new furnace should arrive by Christmas.

 

[Lou]

The best suggestion I have for getting the palladium out would be dimethylglyoxime. Unfortunately the chloride drop will only work if the pH is higher than 5. If it's lower than that an equalibrium will form between h3o+, XCl and HCl, X+ spectator ions. The HCL will react with the nitrate to form crude aqua regia and form NOCl which will waste extremely expensive nitrate and possibly inhibit the dropping of the silver instead pushing the reaction towards nitrate and nitrosyl chloride. So the solution would have a significant amount of silver. Not to mention that silver chloride like gold won't drop out of solution at a low pH. The way to go if you can't make or buy DMG would be to raise the pH with a small amount of base, then use a bit of sodium sulfate to drop the lead out. Then you will have a solution that contains palladium, silver nitrate/sulfate, and copper primarily. The silver can then be dropped out with
Sodium chloride to form sodium nitrate and silver chloride. Once that's done, the palladium chloride remaining can be dropped out with copper metal. This leaves sodium nitrate and copper chloride in solution. You can save this to make nitric acid when it's needed thus saving costs. The reason why I would recommend this over a simple chloride drop besides the obvious selectiveness of the precipitation is the higher efficiency of the drop. Raising the pH allows the reaction to go to completion. However it does take longer than adding DMG and then dropping the silver out with copper metal. If you have access to say hydroxylamine monosulfonate sodium salt, MEK, and sodium nitrite I highly suggest you just make DMG. This process just applies to those who cannot easily get or make DMG. I hope this helps. Being an ametuer chemist, I usually have to use stuff at my immediate disposal. Hydrochloric acid from pool supply stores charcoal briquettes as gas scrubbing compound, Home Depot 5 gallon pails to do my reactions in, and enormous camounts of time designing reaction pathways and researching the millions of reactions transition metals and metaloids can do. I have to read the ingredients of common items and find ways to purify it to a point of being useful. However I do this sort of thing on a far larger scale than most refiners would do e-waste recovery on. I processed a few metric tons of material over 3 years. I am left with about 200 or so kilos of concentrates consisting of the PMS, copper, organics and ceramics. I did an assay and figured out that I had around 40oz a ton of precious metals. Though I could be way off due to my furnace breaking halfway through the melt. I managed to get a refund and my new furnace should arrive by Christmas.

Hey, welcome to the forum!

I really can't say I agree on making DMG unless it's a lot of it. The reaction isn't that straightforward, isn't that high yielding, and there's a lot of organic waste associated. Furthermore, DMG really is way too expensive to use for anything other than analytical purposes in my opinion. Also, DMG should not be used in the presence of gold!

For cheapness on high silver, low Pd, low base metal contaminated nitrate solutions, I stand by removing Ag as AgCl (and probably some PbCl2), rinsing the Pd assay off the filter cake w/ dilute HCl and alkalizing to concentrate the Pd as its hydroxide. Unfortunately, the hydroxide is difficult to wash and the complex sulfite really only works well with chloride free streams.

On high silver, high Pd nitric acid streams w/ a lot of base metals, it's best to again remove the silver as its chloride with excess HCl and filter that off. After that, an aqua regia solution is left behind. Adding saturated KCl solution and cooling will get K2PdCl6 which can be worked up in the usual way.

Hope that helps!

 

[Rougemillenial]

The best suggestion I have for getting the palladium out would be dimethylglyoxime. Unfortunately the chloride drop will only work if the pH is higher than 5. If it's lower than that an equalibrium will form between h3o+, XCl and HCl, X+ spectator ions. The HCL will react with the nitrate to form crude aqua regia and form NOCl which will waste extremely expensive nitrate and possibly inhibit the dropping of the silver instead pushing the reaction towards nitrate and nitrosyl chloride. So the solution would have a significant amount of silver. Not to mention that silver chloride like gold won't drop out of solution at a low pH. The way to go if you can't make or buy DMG would be to raise the pH with a small amount of base, then use a bit of sodium sulfate to drop the lead out. Then you will have a solution that contains palladium, silver nitrate/sulfate, and copper primarily. The silver can then be dropped out with
Sodium chloride to form sodium nitrate and silver chloride. Once that's done, the palladium chloride remaining can be dropped out with copper metal. This leaves sodium nitrate and copper chloride in solution. You can save this to make nitric acid when it's needed thus saving costs. The reason why I would recommend this over a simple chloride drop besides the obvious selectiveness of the precipitation is the higher efficiency of the drop. Raising the pH allows the reaction to go to completion. However it does take longer than adding DMG and then dropping the silver out with copper metal. If you have access to say hydroxylamine monosulfonate sodium salt, MEK, and sodium nitrite I highly suggest you just make DMG. This process just applies to those who cannot easily get or make DMG. I hope this helps. Being an ametuer chemist, I usually have to use stuff at my immediate disposal. Hydrochloric acid from pool supply stores charcoal briquettes as gas scrubbing compound, Home Depot 5 gallon pails to do my reactions in, and enormous camounts of time designing reaction pathways and researching the millions of reactions transition metals and metaloids can do. I have to read the ingredients of common items and find ways to purify it to a point of being useful. However I do this sort of thing on a far larger scale than most refiners would do e-waste recovery on. I processed a few metric tons of material over 3 years. I am left with about 200 or so kilos of concentrates consisting of the PMS, copper, organics and ceramics. I did an assay and figured out that I had around 40oz a ton of precious metals. Though I could be way off due to my furnace breaking halfway through the melt. I managed to get a refund and my new furnace should arrive by Christmas.

Hey, welcome to the forum!

I really can't say I agree on making DMG unless it's a lot of it. The reaction isn't that straightforward, isn't that high yielding, and there's a lot of organic waste associated. Furthermore, DMG really is way too expensive to use for anything other than analytical purposes in my opinion. Also, DMG should not be used in the presence of gold!

For cheapness on high silver, low Pd, low base metal contaminated nitrate solutions, I stand by removing Ag as AgCl (and probably some PbCl2), rinsing the Pd assay off the filter cake w/ dilute HCl and alkalizing to concentrate the Pd as its hydroxide. Unfortunately, the hydroxide is difficult to wash and the complex sulfite really only works well with chloride free streams.

On high silver, high Pd nitric acid streams w/ a lot of base metals, it's best to again remove the silver as its chloride with excess HCl and filter that off. After that, an aqua regia solution is left behind. Adding saturated KCl solution and cooling will get K2PdCl6 which can be worked up in the usual way.

Hope that helps!

good to know. hexchloropaladate is likely the way to go. I mentioned DMG due to selectivness. the problem with DMG is the price, how dangerous the production is, and how volumous the precipitate is. the issues surrounding the separation of palladium and silver is entirely solved by thinking outside the box. if you can't separate the palladium from the silver then separate the silver from the palladium. then the palladium can be cemented out with copper

 

[patnor1011]

Pd pretty much same price than rhodium. Who would have know that...

 

[Lino1406]

Palladium from nitrate solution can be precipitated safely by caustic helped with formalin (mostly as Pd oxide). In my experiments I found no evidence to explosive compound (unlike silver, so don't do that in the presence of it). "30 and more recovery procedures"