PLEASE FOR THE OPINION!

[kole55]

Using too much acid and precipitant is a very common mistake. Hoke teaches us that a troy ounce of gold can be dissolved in four fluid ounces of hydrochloric acid, and one fluid ounce of nitric acid. The forum teaches that to precipitate gold, use a bit more than one ounce of SMB for each ounce of gold expected.

It sounds like you're using hydrochloric acid and bleach (commonly referred to as HCl/Cl) to dissolve your gold. I'm not sure what you mean by "hcl-art", but it may be a translation problem or perhaps a different brand of bleach where you live. The HCl/Cl process just substitutes the bleach as the oxidizer instead of the nitric acid. It will require more HCl than Hoke's recommendation because the bleach is stabilized with a base, which will neutralize some of the HCl. You'll also use more bleach than you would nitric acid because it is not as strong an oxidizer.

The best method, regardless of the process you use, is to calculate how much HCl you think you'll need and add that to the metal. A little extra won't hurt. Then add your oxidizer a little at a time untill all the metal is dissolved. If an addition of the oxidizer doesn't cause a reaction, then try adding a little more HCl. The same applies to your precipitant. Calculate what you think you'll need. Add about 3/4 of that amount and let it react. Once the gold has settled a bit, take a sample of the solution and test for gold with stannous chloride. If gold is still in solution, add more precipitant. If not, you've used enough.

Using just the right amount of chemicals saves money and avoids a lot of problems.

Dave

Thanks Dave! Very useful information, and like I said I did it at the beginning (too much acid and too SMB), and I realized that it is wrong (yes, I read HOKE I took all the books, and I read on the amount and ratios) but as always, the book is one thing and practice something else. I could not be sure because the ratio of the book say 32% HCl and I use it, sometimes 16%, sometimes 20%, but never use 32% HCl. But, no matter what the intensity of use, now I practice very little acid and bleach and the last two processes I used only 20 ml of HCl and 8 ml of bleach and all the flakes dissolve and very nice gold chloride (very thick and beautiful colors. And I thought HCl/Cl not hcl-art and make it up. Now I have one question: after I cut off the fingers of RAM card (fingers processed in AP), whether it is okay to rest with IC chips put in hcl with the intention of chips separated from the boards. With a scalpel is slow and difficult, and I do not want to use the burner. I think the acid should dissolve the solder, after that pick up chips, washed, and go on processing (patnor method) Will it work?

 

[FrugalRefiner]

Yes, HCl will dissolve the solder and the ICs will separate from the boards.

Be careful when writing out formulas like HCl. Proper capitalization is important. Although most readers will understand that when you type hcl, you mean HCl, but that may not be true with other chemicals. Take a look at the examples in my Chemical Formulas post. I provide some examples where the wrong capitalization with the exact same letters would be very different chemicals.

Dave

 

[kole55]

Yes, HCl will dissolve the solder and the ICs will separate from the boards.

Be careful when writing out formulas like HCl. Proper capitalization is important. Although most readers will understand that when you type hcl, you mean HCl, but that may not be true with other chemicals. Take a look at the examples in my Chemical Formulas post. I provide some examples where the wrong capitalization with the exact same letters would be very different chemicals.

Dave

Thank you Dave and you're right formula should be written completely correct!