As I promised in my original post here are my final yield results from these ceramic cpu's.
Total yield = 22.2 grams 8) The scale shows 21.4 gr then I cleaned out my beakers of some residual brown powder and recovered another .8 gr. I started off with 345.5 ounces (21.6 lbs) in total of all cpu's combined (this includes all heat sinks). So some quick math: 22.2g x $53.60/gr= $1189.92 x .958 (23 karat) = $1139.94 x 95% spot = $1082.94. I sold it to a friend at 23k and 95% spot. I paid $825.00 so total gain (without considering operating costs) = $257.94.
Here are some yields as per make, model, etc....
AMD K6- some with heat sink and some without heatsink (I removed heat sink before weighing)- 1068 gr of cpu's = 2.1gr AU = .90gr/lb
Sun Ultra Sparc IIe- 100.1 oz (includes 69 oz of heat sinks)= .75gr AU = .12gr/lb if you include heat sinks in weight. These yield about the same as some green fiber cpu's so I guess that is why the big boys pay so little for them. A waste of time in my opinion for the average small time hobbyist refiner.
Intel Pentium 1 (no gold top)- 2174gr= 5.1gr AU= 1.07gr/lb
Intel 486- 995gr= 6.4gr AU = 2.95gr/lb Sorry- forgot to take picture, but these cpu's do yield much more than many others per lb.
The balance of the rest of the cpu's seen in my original post were all too few in number for me to do yield tests on- didn't have the time unfortunately.
As far as the gold plated heat sinks/cover plates go I have this to say. There are basically two types involved here. The thick kovar ones like on the top of the Pentium Pro, and the much thinner, and smaller cover plates seen on the bottoms of some chips as well as on the tops of rectangular 'centipede' ic's. The thick kovar heat sinks yielded 1.0 gram, while the thinner cover plates yielded 3.9 grams. I forgot to weigh these so all I can say is that I was very surprised at the yield for the smaller thinner cover plates. I processed all of these in nitric acid. Perhaps in the future I will process the kovar heat sinks in a cell instead, but I had too few of them to use a cell this time. Indeed the smaller plates were very worthwhile to process.
This was a fun experiment albeit very labor intensive. Next time I will process them in much larger batches as I will not be doing a test for yields. All of the dissolution was performed by poorman's AR (HCL with small incremental additions of sodium nitrate) on a hot plate. I am not experienced with the use of acid/peroxide on ceramic cpu's but I would like to investigate that. If I could put all of them in one bucket with acid/peroxide to dissolve the base metals then proceed with hcl/cl to dissolve the foils that would save a tremendous amount of time. Anyone care to chime in here? Thanks in advance!
I read on some previous post (I believe it was one by Harold) that if you drop a button of 24k AU in your dissolved chloride solution then you don't have to evaporate it down nearly as far(to a syrup) to get rid of the excess nitric acid. I was having trouble with the smb drops taking a long time to react so I started using this button in the chloride trick and it really made a difference. The subsequent drops with smb went very quickly (maybe one hour to drop 99%). I can only guess that before the button addition I was not ridding my solution of the excess nitric acid.
I started this with the intent to do a much more scientific test a far as yields go but it got out of control time wise. I do actually have a day job, thankfully. I was going to attempt using oxalic acid for my second refining (as per Sam @ Gold-n-Scrap) but time got away from me. I had to sell the button to pay mortgage. There is always a next time- until then- it's been real!!
