I just recently did a small batch of these using Poormans AR, all were missing their legs though, I would cut them off and throw them in with batches of pins and connectors, putting the hat part aside for later.
I had been accumulating these because I didn't know how I wanted to process them, in particular how to get rid of the hat, which I never did figure out an efficient and effective way of doing that, so I had to settle for merely compromising the integrity of the hat as opposed to eliminating it.
What I did was to use a belt sander to grind off the top of the hat, just a real quick 2 second grind worked fine, thus exposing the insides. I did this mainly so that both walls of the hat would be subjected to my solution instead of just the outside, so in other words I did this solely to speed up the dissolution process of the actual hat itself.
So I think the step of grinding the hats was not necessary, the hat would dissolve whether compromised or not, but another aspect of them pushed me to do this, that they might float, especially when heated. Maybe if they floated it wouldn't have mattered, but instinct told me I wanted to avoid that, so again the grinding solved that potential issue.
The hats I processed were of all sizes, from the smaller ones which are about 3/16" to the larger ones of about 1/2". They were of all different types too, some with green or brown glass insulation, some with white ceramic.
What I relied on to do these was the reactivity series, I wanted to let the solution dissolve as much base metals as possible before it started attacking the gold, so I did this in a few increments, pouring off the solution containing only base metals. I would check with stannous before starting over with fresh solution, when the test became positive is when I went ahead and dissolved everything.
So it should go without saying that by the time I got the positive stannous test, there was hardly any base metals left to dissolve and pollute my solution, not only was the actual steel hat material long gone but also most of the base material as well, the bases reduced to shells of their former selves.
By the way, I should mention that I incinerated the hats before subjecting them to the Poormans AR, I did so after compromising them with the belt sander.
All in all this was a pretty easy process, but besides that, I can't complain about the yield either, considering that I had written these off as not worth the hassle to deal with, thus why I had been putting them aside and avoiding doing anything with them.
Problem is, I didn't care what, if anything, I got out of processing these, so I didn't take any notes or document any aspect of this refining job, sure wish I had weighed the batch after doing the incineration step.
As best I can remember, the hats filled a 500ml beaker somewhere from the 50ml to 75ml amount, so I didn't process a whole hell of a lot of them, but keep in mind that 50% of them were of the small type, also that they didn't have their legs or tops, so in other words it was pretty densely packed down there in the bottom of the beaker.
After dropping the gold from the initial filthy solution and doing a second refine, this small batch of hats yielded a .63g button, not bad if you ask me. If they had still had their legs, maybe I would have gotten a gram out of it.
What I like best about what I did, besides the part about narrowing down the process to the point that the hardest part was using the belt sander, which wasn't a big deal at all and maybe not even needed in the first place, is that I didn't have to resort to using expensive nitric, that .63g button was incredibly cheap to produce.
