# Cats and induction?



## elfixx (Mar 1, 2011)

Perhaps that's the worst question I have ever asked but I am currious and I have absolutly no knowledge on catalytic converter refining and PGM recovery from them, what would happen if one tryed to melt honeycomb in an induction furnace? From what I know the honeycomb is made of ceramic and the inside is coated with PGM, wouldn't the value melt using a high frequency induction furnace and prety much leave the structure pretty much intact? or would the whole thing kind of melt in some slag mix containing only small amount of metal which would be almost impossible to recover in that state? or even melt into a fluid enough mix that could allow seperation by simple gravity using a cone mold? I am kind of trying to figure out how major cat refiner do it. I'm not convinced they're processing tons and tons of this stuff in ar....


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## lazersteve (Mar 1, 2011)

I've read that they are most likely using a base metal to collect the PGMS from the molten comb material. 

I've also read that they use plasma furnaces to melt the raw, clean, cats.


Steve


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## nickvc (Mar 2, 2011)

I think if I remember correctly GSP posted a link to Techemet who do convertors by the ton and I think Steves right they use a huge plasma furnace and recover everything steel, PGMS and even the carbon.


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## elfixx (Mar 2, 2011)

Basicaly something impossible for someone who would want to start a descent size cat refining operation at resonable cost...


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## 4metals (Mar 2, 2011)

Don't know if this would work on cats but a flux containing cryolite will help liquefy the ceramic so copper could be used as a collector to scavenge the pgm's in the ceramic. Pour it into a cone mold and assay the metal. Then crush up the slag and assay it as well. Then you'll know.


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## rusty (Mar 2, 2011)

4metals said:


> Don't know if this would work on cats but a flux containing cryolite will help liquefy the ceramic so copper could be used as a collector to scavenge the pgm's in the ceramic. Pour it into a cone mold and assay the metal. Then crush up the slag and assay it as well. Then you'll know.



As always great information 4metals hope you do not mind my adding the wikipedia link below.

http://en.wikipedia.org/wiki/Cryolite


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## 4metals (Mar 2, 2011)

and you can buy it here http://www.washingtonmills.com/products/cryolite/


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## qst42know (Mar 3, 2011)

What type of crucible would be required?


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## 4metals (Mar 3, 2011)

Clay graphite, it is hard on crucibles. Back in the '70's I melted ceramic substrates with cryolite in the flux. It was effective. So it's worth a shot.


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## elfixx (Mar 3, 2011)

Sound like something I'm going to try as soon as I get my hand on a induction furnace. Extracting value in metalic form alloyed with copper quickly with the use of heat and some flux would shure be the best option to process medium to large quantity. That shure going to take a few month before I get myself a induction furnace but I'll be posting result as soon as I try it out.


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## 4metals (Mar 3, 2011)

I've done this with a gas melter, you can add sodium nitrate to get the temperature of the flux mixture up.


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## elfixx (Mar 3, 2011)

A propane furnace won't reach over 1100 C that wont be able to melt Pt, and both of my gas furnace are too small to hold a big enough crucible to handle resonable quantity of honeycomb.


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## 4metals (Mar 3, 2011)

A gas furnace gets hot enough if the oxygen is present. Forced air plus propane plus an oxygen source in the flux will melt the copper which will take in the other metals. That's the job of a collector.


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## Platdigger (Mar 3, 2011)

Not saying it would be the way to go, but just to illistrate the concept, you could put platinum into an alloy with aluminum at an even lower temperature.


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## elfixx (Mar 3, 2011)

That's absolutly logic  
But I have a concern about this process, I've read somewhere else on the forum that Rh will not be fully absorbed in a metal that can be oxydised. Would that mean copper would probably not be able to catch all the Rh?


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## 4metals (Mar 3, 2011)

> I've read somewhere else on the forum that Rh will not be fully absorbed in a metal that can be oxydised.



I've not heard that before but it is possible. Silver could also act as a collector if that is an issue. I would think you would only use a few ounces per cat anyway.


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## Lou (Mar 3, 2011)

Silver is far better at collecting PGMs than copper. Nickel and nickel sulfide are also popular collectors. 

Cryolite and fluorospar are both extremely aggressive flux agents. Copper is usually used because it can be percolated through the flux mixture and then electrorefined. 


A naturally aspirated propane burner can easily get to 1550*C. I've melted cast iron with one such burner (called a Monster burner, Rupert Wenig's design).

Lou


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## elfixx (Mar 3, 2011)

What kind of electrolyte is used in copper electrorefining? I am wondering because if the copper containing PGM is electrorefined, the electrolyte must not have the capacity to disolve any of the PGM. Wouldn't a electrolyte made copper disolved in nitric acid also disolve Pd? And I guess it has to be done this way since disolving the massive amount of copper in nitric would be way too expensive and there would be massive quantity of fume and residual copper nitrate solution to deal with.


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## Barren Realms 007 (Mar 3, 2011)

elfixx said:


> What kind of electrolyte is used in copper electrorefining? I am wondering because if the copper containing PGM is electrorefined, the electrolyte must not have the capacity to disolve any of the PGM. Wouldn't a electrolyte made copper disolved in nitric acid also disolve Pd? And I guess it has to be done this way since disolving the massive amount of copper in nitric would be way too expensive and there would be massive quantity of fume and residual copper nitrate solution to deal with.



I have seen reference to sulfuric used.


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## elfixx (Mar 3, 2011)

And sulfuric wouldn't disolve Rh? It look a bit tricky


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## Barren Realms 007 (Mar 3, 2011)

elfixx said:


> And sulfuric wouldn't disolve Rh? It look a bit tricky



He was asking about copper was my understanding.


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## elfixx (Mar 3, 2011)

What I wanted to say is that the electrolite used must only disolve and plate out copper. Think of gold and silver refining, a silver cell electrolyte is made of silver nitrate disolved in nitric, silver AND copper is being disolved at the anode but by controling the voltage it plate only silver out, plus gold is not solube in a nitric electrolyte. Same thing with a gold cell, it will disolve both gold and copper and plate gold only as long as you keep the voltage low, and silver is turned into silver chloride which is insolube. In a copper refining cell you cannot control voltage to choose what you are plating out, if the electrolyte allow dissolution of PGM it will plate allong with copper since it deposit at a lower voltage than copper. The electrolyse must not allow any PGM to dissolve for the value to be deposited as slime in the anode bag. As far as I know AR will disolve Pt, nitric acid Pd and sulfuric Rh. Therfore I would guess the electrolyte cannot not be made from these.


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## 4metals (Mar 4, 2011)

If you use silver as a collector you can refine in a cell, the Pd will go into solution and eventually foul the cell and the platinum and rhodium will be in the slimes. I do not know what concentration of Palladium a silver cell can hold before it begins to co-deposit.


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## Harold_V (Mar 4, 2011)

4metals said:


> If you use silver as a collector you can refine in a cell, the Pd will go into solution and eventually foul the cell and the platinum and rhodium will be in the slimes. I do not know what concentration of Palladium a silver cell can hold before it begins to co-deposit.


I can't address that in the way of percentages, but when the electrolyte starts turning green, you're on the edge of co-deposition. I parted a lot of palladium contaminated silver and often had to part the crystals a second time to remove traces of palladium. They can be placed directly in the basket without melting, and parted with perfect results. I'd use a portion of each harvest to make electrolyte for the succeeding batch, so I'd know if there was contamination of any consequence contained in the harvest. 

Harold


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## Oz (Mar 4, 2011)

I do not personally see using a silver cell as the best option in this case, and I use silver to remove PGMs from karat gold by inquartation then part in a silver cell on a regular basis. I think in this situation if you are going to use a silver cell one should quit thinking of it as a means to produce fine silver. Instead think of it as a way to effect a limited separation of your Pt and Rh. No matter what, you will still be left with some silver and palladium in your slimes along with your Rh and Pt that will still need to be separated from each other. Even if you do not get palladium co-depositing with your silver at the cathode, you will still have both in your electrolyte and need to separate them as well. 

For that reason if I was using silver to collect PGM in a melt I would focus on how much platinum can I have in my silver and still have it near completely removed with a nitric digestion after the fact. This would leave you with reasonably clean Rh as a solid residue and a nitrate solution of Pt, Pd, and Ag. If you are careful not to use an excess of nitric, you can then precipitate your silver quantitatively as the chloride with HCl. The remaining solution would be Pt and Pd with little nitric. At that point you could do the classic triple evaporation with HCl additions, and then proceed with precipitating the Pt and Pd salts. 

However I think a better alternative if you wish your Pt and Pd separate would be to avoid the triple evaporation and to cement the Pt and Pd with zinc, then use nitric to remove the Pd from your Pt. 

To be clear, only some of this is based on the processes that I currently use. But at this late hour it is what seemed the most effective way that I would handle it if I needed to. None of what I am suggesting will give you better than .99% purity on anything, but it will get you close enough to know if you are being treated fairly when you sell, or give you a reasonably clean product to refine further to industry standards. I look forward to corrections and other alternatives from those with more hands on experience than I possess.


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## elfixx (Mar 4, 2011)

Problem is, to process large quantity (100's of kilos) of cat that would require large amount of silver and therefore large quantity of silver chloride to deal with after separation of silver/Pd. I was thinking copper as a collector because another forum member claimed to have done it with 150kg of cat honeycomb in a large furnace. Copper would be cheap and if there is a way to get rid of the copper in a refining cell leaving all PGM beheind as anode slime that would be a seriously effective way of recovering these metal.


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## elfixx (Mar 5, 2011)

I'm wondering if chlorination process could be used to seperate PGM from copper? If I am right chlorine gas at high temperature will disolve any base metal but won't affect Pd Pt and Rh. That could be a effective way get rid of all the copper and be left with mixed metalic pgm.


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## Lou (Mar 5, 2011)

That depends on the temperature.

Chlorine and all the halogens are highly effective at attacking gold and other platinum group metals at room temperature and above. What matters is how stable their respective chlorides are to disproportionation.

Louis


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## 4metals (Mar 5, 2011)

Getting ahead of ourselves here, we don't even know if the car runs and we're worrying about changing the tires. 

First mix up the appropriate flux and then try the melt once with copper as a collector and once with silver as a collector. See which mix works best and see how much metal was left behind in the slags. (by running a sweeps assay) 

Then we can discuss separation from the most effective collector.


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## elfixx (Mar 5, 2011)

All right  as you said that might be a little too soon to discuss separation. But for some reason my brain can't stop thinking about it, I've wanted to work with PGM for a long time but never had my hand on any of these fascinating metal. Even if I never had any demand for PGM or refining of these I feel the service offered to my client is incompete. Not to mention the potential in cats refining that could turn my small business in a much more profitable organisation.


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## 4metals (Mar 5, 2011)

Well if you have a small gas melter and an assay lab you can do some basic testing and be ready for the day when you have that induction furnace.


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## skippy (Mar 6, 2011)

My first thought would be is how much money is the cryolite and fluorspar, and is it something that you'll be able to reuse or sell , or will you have to pay to dispose of as a hazardous waste?


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## jeff216410 (Mar 9, 2011)

If trying to melt the catalyst substrate in a furnace, what temperature would need to be reached? I too have been curious what temperatures the big cat refiners acheive in their arc furnaces that melt the substrate.


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## kjavanb123 (Sep 22, 2013)

What an interesting post here, and sadly it never continued so we can see the result. I have access to varites of sizes induction furnaces here right now, and what I gathered from this post, first honeycomb is shdredd then crushed or should we just hammer the cat into small pieces?
Then preparing the flux, silver, copper or nickel as collectors, then sodium nitrate as a temprature controller. Is collector added at stage of when everything is molten inside the crusible? Or pre mixed with the cats?
I will be visting the guy who build the furnaces in few days for a project related to escrap I thought to give it a try with converters.

Regards,
Kevin


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## 9kuuby9 (Nov 6, 2013)

A very interesting post I must say, Just what I needed for another similar project!

I've started a similar Topic on processing MLLC's by physical means of melting.

Feel free to chime in and advice correct fluxes, improvements and or gear on this Topic; http://goldrefiningforum.com/phpBB3/viewtopic.php?f=39&t=19537&p=198228#p198146

Hopefully I can test this process soon enough and give an detailed post on the subject after the experiment.

I was planning to use Borax and silver as collectors and to ease the melting of the Pgm's.

Again I'm not very experienced in fluxes, but would be adding Cryolite and or more silver ease the process in it's task?

Kind regards

Ben


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