SilverNitrate said:
I'll post a pic a bit later of the finished and dried gold powder. And it looks to be of good quality.
The appearance means very little. It's the purity that matters, assuming you care. Many here do.
The real test is how it melts. If you can melt it without a flux cover, and have it remain shiny, with a broad crystal structure on the surface of the button, and a deep pipe where it last solidifies, you may have my attention. Right now, I still don't like what I'm being told.
Refining gold is no stranger to me, having done it for more than 20 years, many of them as my sole source of income. Not that I consider myself the sole authority, far from it. I simply know what it takes to get pure gold, and introducing contaminants to it isn't exactly the way to go. I do agree, copper is a great way to recover gold from solution if you aren't concerned with purity. It leaves behind many contaminants, but is NOT totally selective. If you have any of the platinum group in solution, they, too, are precipitated. That defeats the purpose of precipitation, with one exception. I have advised folks to use it when they've screwed up and have dissolved an abundance of base metal with the values, but otherwise I see little to recommend it.
Going a bit further, I'm NOT an advocate of washing precipitated gold with nitric. Once the gold has been precipitated, it's very easy to re-dissolve when nitric is re-introduced. One can do an admirable job of washing precipitated gold using HCl (having come from a chloride solution when it's precipitated, the introduction of more HCl isn't risky), but when precipitating with copper, that is no longer true. HCl has little effect on pure copper, certainly not enough to cleanse it properly.
Though I never used H2SO4 in a blender, only HNO3, the blender pitcher I have used more than a dozen time for 3 years and have seen no diminished performance not even any leaks from holding the acid or products.
That surprises me, I must say. I've used enough nitric acid to know that if it's presented to a copper alloy, the reaction is sure and swift. How you're avoiding damage I don't understand. One thing is sure, if it gets past the seal, it won't take long to destroy the bearing----otherwise it wouldn't have any effect on the gold, wouldn't you say? Personally, I wouldn't be willing to risk the loss, nor the danger of nitric acid entering the motor, which it can do if it leaks. None of this is sound chemistry, not in my book.
H2SO4 will along with heat dissolve copper, I have used to make CuSO4.5H2O all the time (blue crystals used for copper plating)
Absolutely. It dissolves the oxides----but you can boil copper for hours on end without dissolving the metal itself. Unless you are dealing with concentrated sulfuric, you are misinformed. Do you recall my telling you that sulfuric acid is used as a pickle for copper? Why do you suppose that is?
Next time you have the opportunity, place a solid piece of copper in some sulfuric and give it a prolonged boil. Inform all of us how much gets dissolved. As I said, I've boiled copper components to remove oxides. There's no way in hell they were dissolved. Physically, those that had been boiled were identical in every way aside from surface finish. Mind you, I'm looking at this from the perspective of a machinist, so I'm very capable of taking measurements to tenths of thousandths, and have the necessary instruments.
If sulfuric was the solution to dissolving copper, there would be almost no need for the work-arounds these guys have created, a result of the difficulty in obtaining nitric acid, at least here in the States. It doesn't work, so until you have done it successfully, it would be a kindness to quit telling folks it does.
My OP was not meant for purifying the gold, but just rather cleaning it up because bits of solid copper will be in the gold precipitate. I like to use the blender because it makes the gold precip denser, (I can fit 20oz of it in a 4oz bottle) where as if not it would be half that
Given the method of precipitation, I guess I can understand that. It still would be poor reason to use copper, however. There are precipitants that will yield quite dense gold -----one of which is SO2. It not only yields dense precipitate, it also yields gold without including a contamination, aside from drag-down of residual metals. The use of copper doesn't eliminate that problem either, so there is no advantage. I'm totally mystified by your insistence in its use. It makes no sense, not if you're trying to recover pure gold.
Also I usually gets 1/2 oz of undissolved copper out of my 10 oz gold precip batch.
Interesting.
Need I say more?
You can recover your gold without introducing metals. You'd be far ahead of the game. Can you explain it in terms that will have me understand your logic?
I'd like to see this Hoke book, is it avail electronically?
I know of no source aside from buying the book. It's not expensive-----not if you know of only your method of dealing with gold. You stand to learn so much, it would be a bargain at $300. You can purchase it for less----about $75. It's worth every dime----especially when you're using such bizarre procedures. You can be proud to have come so far without good guidance, but you really need to explore better procedures unless your intention is to fill those 4 ounce bottles with impure gold powder.
Here's a source for the book. Please do yourself a favor and invest in a copy. It will be very revealing.
http://www.gesswein.com/catalog/catalog.cfm?cat=12&sub=3&subsub=59&catalog=1&CFID=1471004&CFTOKEN=30985426
If you are not successful at Gesswein, there is another source. Let me know and I'll provide the information. A recent post indicates that Gesswein has a lower price. The title you are looking for is Refining Precious Metal Wastes, written by C.M. Hoke.
For the record----I have no personal interest in the book, or in Gesswein. I'm simply trying to give you some much needed guidance via Hoke's book. It's very good, especially for those that don't understand acceptable testing and refining procedures. You need not be a chemist to understand the book-----it's written in layman's terminology, and is a step by step instruction, unlike almost any other book I've seen on refining.
Harold