Processing of ceramic processors with cyanide

[scorpion1971]

Hi valuable forum members,


In a work I did the other day, I used ceramic cpu's with cyanide. I broke both the veneer and the pins and the crest, and took all the gold in it into the cyanide solution. Then I settled with zinc. I put 2 zinc rods in the solution and let them stand overnight. Then, the solution was filtrated and the precipitated solid was washed with hot water 3-4 times. I cleaned base metals with nitric acid. I then processed it with aqua regia and precipitated gold with SMB. I need help on a topic. As an example. 30 Gr NaCN = 15,93 Gr Free CN. (For Free CN = NaCN x 0.531). I used 2 zinc bars to prevent the gold from dissolving in the solution. To avoid doubt, 15.93 Gr. if I use zinc dust to correspond to the free cyanide, can I prevent the gold from being left undisturbed and the gold from being re-dissolved again? The help will be really appreciated.
Sorry for the bad english.

Best Regards,
Mehmet

 

[anachronism]

Mehmet

What pH were you running the cyanide solution at and what were you using as your pH regulator?

 

[scorpion1971]

Anachronism,

I work at pH 12. I use NaOH if necessary, but I do not need it.

Best Regards,

Mehmet

 

[anachronism]

Thanks - what amount of NaCN did you use per litre?

 

[scorpion1971]

I used 30 Gr NaCN per litre.

 

[anachronism]

Thanks for the info - final question are you using an oxidant?

 

[scorpion1971]

Of course. m-NBSS.

 

[anachronism]

Of course. m-NBSS.

OK thanks for the info. Can I ask why you used that as opposed to peroxide and how well do you understand the differences between the two?

 

[scorpion1971]

Of course. If I use peroxide, I need to finish it in a short time. Because he's starting to crack cyanide. But there is no such problem for m-NBSS.

 

[silversaddle1]

I have a question. I thought the cyanide would only strip gold off the exposed surfaces. How can it be effective to strip the gold that in contained inside the CPU? Maybe a stupid question, but you know, the more you know!

 

[scorpion1971]

You are absolutely right. I broke the processors to get the gold in the ceramic. But I forgot to take photos.

Mehmet

 

[nickvc]

You may want to run the cpus again because if they have solid bonding wires or gold soldered lids the cyanide will not remove it all easily, using m-NBSS will make full recovery difficult to say the least whereas peroxide makes for a simple and easier recovery of the gold.
With the cpus I’d suggest a very good rinse and then into AR to check you have recovered all the gold, you can do a small sample to test and check for gold using stannous.

 

[silversaddle1]

You are absolutely right. I broke the processors to get the gold in the ceramic. But I forgot to take photos.

Mehmet

Thanks for the answer. I don't refine but it doesn't mean I don't read up on the processes! :G :G

 

[anachronism]

The free cyanide isn't your issue it's the oxidant. As Nick alluded to it's simpler to use Peroxide as it degrades thereby losing it's oxidant properties. I'm not au fait with destroying m-NBSS because having tried it a couple of times I steer clear of it like the plague.

 

[nickvc]

I think Jon will agree that just leaving the cpus in cyanide will not dissolve any solid materials even plated materials need to be agitated to strip effectively, if you had a constant flow of fresh solution going over the solids it will ecentually strip the gold but just dipping will not remove any decent percentage.

 

[goldsilverpro]

The cyanide will strip the plating. It won't touch the gold/tin or gold/silicon brazes, if those were used to attach the lid and/or the chip. Also, it would take a long time to dissolve the gold wires, which are at least 14 times thicker than the gold plating.

 

[scorpion1971]

I have previously read on the forum that the cyanide process is not suitable for CPUs. But when I tried, I uncovered both the cover and the pin covers, and the whole of the broken wires. I checked it thoroughly with a magnifying glass. The result is great. What I wonder is to settle all the solved gold. At the same time, gold does not dissolve. I used 2 thick zinc bars for this. But I do not want to leave the job to chance. Would it be right to use too much zinc dust for this?
Mehmet

 

[Topher_osAUrus]

Ill buy your cyanide ran cpu's!
50 cents a lb!

 

[scorpion1971]

Ill buy your cyanide ran cpu's!
50 cents a lb!

It's not funny ! You first learn this process, then you comment.

Mehmet

 

[nickvc]

Ill buy your cyanide ran cpu's!
50 cents a lb!

It's not funny ! You first learn this process, then you comment.

Mehmet

Mehmet I and think everyone else is trying to tell you that you may well still have gold left on your treated cpus, somrun a small sample in AR after rinsing all the cyanide off and test the solution with stannous.
The one big problem with using cyanide is that there is no simple way to test you have all the gold out of solution apart from an assay of some sort.