problem after being sold pure zinc that was not

[Slaughlin79]

I have 3 gallons of pgm solution that are extremely contaminated with I’m almost tin. I bought pure zinc bars, or at least I was told they were, and put them in my solution of cats and when there wasn’t much of a reaction at all I knew something was up. But being my first attempt at processing cats I kept the bars in the solution just in case. I would’ve suspected that adding a bar with tin in it would create a bunch of nano particles like if I had dropped stannous chloride in it, I was wrong. A very small amount of black precipitate formed but still tested very strongly for pgms.

I removed the bars and not knowing yet that the bars that I had removed contained tin and god knows what, I decided to drop everything with copper. Well as soon as the copper hits the solution an almost black, really a orange black puddle forms and continues to bleed off of it
and it did this for a week before a decided to remove copper and do some reading. That was 2-1/2 to 3 years ago and now that I’ve just about got every other solution done and cleaned up I want to fix these last 3 gallons but there is nothing that I have read or searched that taught me how to correct the problem.

Before storing these solutions which are concentrated, I added 30 percent hydrogen peroxide to re dissolve the pgm nanos. I’m calling them pgm nanos bc I cant find the correct term like if I were talking gold I would call it purple of cassius.

Where do I need to start? Unless I completely missed it I didn’t find anything that dealt with my situation in Hokes book. I really want to finish this stuff up and be done with it for good because I don’t like working with pgms at all because of the toxicity.

 

[FrugalRefiner]

When in doubt, cement it out.

I don't know the origin of your solutions, and you may not either. But when you have a big mix of materials, the first step is to test the solution for values. If the test is positive, you can cement them out on copper to recover any values before treating the remaining solution for waste. I know you said you used copper before, but it sounds like you had a lot of unused acid.

Dave

 

[Lino1406]

Sometimes people consider tin to be zinc because in German tin = zinn

 

[Slaughlin79]

I know exactly where the solution came from. It came from cats that were soaked in HCl and with additions of dry chlorine. The thing is I introduce quite a bit of tin bc I was sold something that was suppose to be pure zinc but it was actually zinc welding stick. They use them for touch up when a pice that had been hot dipped galvanized gets scratched deep enough to expose ste they heat up the area and spread it on like a crayon. I didn’t know that’s what it was until I researched a lot more into it. But it was too late by then. Now I have a solution that is so dark a brown it’s almost black and stannous test still shows positive but nothing is cementing out. This is the only batch I’ve had problems with.

See I didn’t have problems with this small batch. There was a little contamination you can tell by the clear on bottom and orange on top,I’m guessing a small amount of tin got introduced that you couldn’t do anything about. Now imagine that but 100 times darker and from top to bottom with noting solid falling to the bottom. I’ve been using my stirrer to keep the solution churning but have stopped it for a while and there is nothing collecting on the bottom. I don’t know what to do. If I can’t find a solution ima flush it

 

[butcher]

is that a galvanized pipe nipple?

 

[Lino1406]

The tube shown in pic, looks as having PM's coating

 

[nickvc]

My only thought would be to re dissolve everything filter and then cement using copper bars plus an addition of an air bubbler, it can be a slow process but at least you should just have PGM blacks left to work with.

 

[AshesoftheUniverse]

My only thought would be to re dissolve everything filter and then cement using copper bars plus an addition of an air bubbler, it can be a slow process but at least you should just have PGM blacks left to work with.

Copper works well and results in a coating that is quite colorful and a good qualitative indicator of what is there. Once the values are precipitated they can be scrubbed-off the Copper and treated accordingly.
It's a bit messy, but worth the effort.