Platinized titanium anodes

[4metals]

I remember from years ago in my electroplating days, the standard way to "test" if a platinized titanium anode still had a Platinum coating was to heat a section with a torch and when it cooled if there was a circle of discoloration the platinum has worn off. This is what would indicate a "no platinum remaining" result.



This is what a platers forum says about how to test the anodes for Platinum. http://www.finishing.com/108/70.shtml

I was at a client's shop recently and he had received in a box full of these anodes, and every one had the discolored ring indicating they had been tested. I told him what the discolored ring meant and he called the customer to tell him. Well the customer insisted there was platinum. OK, the customer is always right so I set up to see if we could get some Platinum off of them.

We used a shear and cut the anode into strips so it would fit into a heated reactor and diluted some Hydrochloric to 20% to cut down on the fuming. Then the nitric was added and the reactor heated up. Well after about 1 hour I tested the acid and to my surprise the acid had a healthy Platinum stain.

So needless to say all these years I've thought the ring meant replace the anodes with new platinized anodes or get the old worn ones replated. Apparently, what is no longer the best for electroplating still has some value to refiners.

 

[upcyclist]

I'm wondering if the discoloration doesn't meant the platinum is gone, but rather it's thin enough for the Ti to come up and show through it? Just like with gold plated jewelry, if you heat it, you can bring the copper to the surface--at least that's what we call it in the shop. It's possibly also the gold migrating/alloying with the basemetal.

So, the heat test may indicate that the anode is past it's useful life, but that doesn't mean ALL the plat is gone.

 

[Topher_osAUrus]

...how much platinum do you think has been discarded as nill from that test?
:shock:

 

[anachronism]

So needless to say all these years I've thought the ring meant replace the anodes with new platinized anodes or get the old worn ones replated. Apparently, what is no longer the best for electroplating still has some value to refiners.

Which just goes to prove that we never actually know it all. I don't know about you 4metals but even though I'm years behind you regarding experience I am still astounded every day at something new that I learn.

It does make you kick yourself occasionally doesn't it?

 

[4metals]

The acid left a nice stain but clean acid will stain a vivid red with a few grams of Platinum. Each anode is 6" by 9" and there were about 25 of them which when cut filled a 20 liter reactor nicely. It had about 12 liters of aqua regia in it to dissolve the Platinum. I will give them about a week and see what the yield was. I am curious as well.

I am still astounded every day at something new that I learn.

Learning is a good thing and I'm never embarrassed by it, it's witnessing something and ignoring what you've seen and not applying it that is bad. I always make notes when I see something new. And thanks to a forum like this, it is easily shared.

 

[anachronism]

Learning is a good thing and I'm never embarrassed by it, it's witnessing something and ignoring what you've seen and not applying it that is bad. I always make notes when I see something new. And thanks to a forum like this, it is easily shared.

And your highlighted comment is the mantra that I live by. Thank you for expressing it so clearly.

 

[Lou]

Fast way to do those is AC electrolysis in HCl, in, you guessed it, a titanium tank. Bale them up and get ready for the chlorine! All done when Pt plateaus on ICP. Spend more time setting up and analyzing than stripping.

We have done a lot of Pt/Ti, Ta, Nb. More than a few tens of tons. Yields can be very good to almost not worth doing.

 

[anachronism]

Lou

Is there any way to assess in advance or is it literally pot luck?

 

[Lou]

No expedient way to be sure. Even heat tinting them with w big rosebud is too slow when they are in quantity and even then, it just shows grade not yield--they'll still have Pt. Now if the whole lot comes in and they're all different colors...don't expect much. Also, there's frequently some sort of grease on the solid parts (not the expanded mesh).
The titanium ones don't weigh much so usually most valuable on a mass basis.

Often there are Mixed Metal Oxide anodes with Ru present.

 

[4metals]

I spoke to the refiner who processed these anodes today. There were actually 32 pieces and each anode was 6" x 9" and every one had the circular discoloration from being tested with a torch.

The total recovery of ammonium chloroplatinate, dried and weighed, was " just a hair over 1 troy ounce." Considering it takes 2.3 grams of ammonium chloroplatinate to produce 1 gram of the metal, he recovered about 13.5 grams of platinum.

.43 oz of Platinum at $1050 = $456. So each one was worth about 14 bucks.

There won't be a lot left over after charges for sure!

 

[Lou]

Most of what we saw were either 4-5' long strips, 3-6" wide (those were columbium) or 4'x8' sheets of expanded Ti

 

[4metals]

I can understand a manufacturer using anodes that size looking to a specialty refiner to process those anodes but the size the ones my client processed were the kind a small job shop plater would use and possibly some of our members would come across them. At less than 1/2 gram of Platinum each they are a low profit proposition for an sizeable refinery. For a small operator, as a toll refine it is different.

It would be interesting to know the plating thickness applied to these when they are new.

 

[Lou]

5 um.

At least the ones I have experience with.


I think the reason I saw the big sheets is that they were defective from the manufacturer...