Salt in Acid

[chawimac]

Update.

I inquarted the metal once again with some .900 Ag and made sure it was 25% Au on the XRF. I made the popcorn and tossed it in with a potion of half distilled water and half of the Nitric I have.

Curiously all went well. Much more complicated than simple AR but all in all well. Looks like I have some copper or nickel now as the liquid changed color after boiling. The original sample had no color as it was pure gold and silver.

All the popcorn dissolved after adding a bit more nitric. I then proceeded to the AR process.

It was horrible to filter this! Much more difficult. The gold just did not want to settle down! Any tips???

The problem, it turns out was the language barrier, as I failed to read the water bottle correctly. The water used in the first test was an electrolyte solution!!! Hence the salts. Once that ran out the problems stopped. Go figure.

 

[eeTHr]

It was horrible to filter this! Much more difficult. The gold just did not want to settle down! Any tips???

Are you referring to the gold remaining in the nitric, or to the gold powder precipitated from the AR solution?

 

[butcher]

Sounds like tin, in solution making filtering a problem.

 

[eeTHr]

Sounds like tin, in solution making filtering a problem.

I took it to mean that his gold wouldn't settle to the bottom.

 

[Harold_V]

Heh! From my understanding, the solution wasn't separated from the honeycombed gold, but was, instead, allowed to remain while the gold was dissolved. Sounds to me like there's a lot of silver chloride present, with dissovled gold well mixed within.

Please tell me I'm wrong.

Harold

 

[eeTHr]

chawimac---

All the popcorn dissolved after adding a bit more nitric. I then proceeded to the AR process.

Strictly speaking, the above sequence doesn't make any sense, either.

Overall, a very confusing post.

I would recommend that when posting, you slow down and explain everything in exact sequence, and don't leave out any steps by assuming that people understand that they were done. If you want help in catching any possible errors---how is anyone supposed to know what's a possible error, and what you're just assuming that we somehow know that you actually did?

It might be difficult to get help from people that you have just confused. 8)

 

[chawimac]

Hehe, here I'll slow down a bit. Sorry.

It helps if you read the whole thread as there were a lot of issues involved.

Where I am having problems, or rather inconveniences is in filtering gold that I dropped with SMB at the end of the AR process. I had a pretty good handle on the AR process of refining, where I am expecting a clay colored gold mud/sludge. In the in-quart process, when it comes time to drop the gold with SMB, the reaction is different as the gold is different. The color is much darker and it is not a slime/sludge. It is rather a very fine powder that does not want to gravitate to the bottom of the container. I know I am getting most of the gold I am supposed to because the numbers add up, but the filtering process is much more difficult that a basic AR process that does not involve previous Nitric/In-quart process.

As far as tin being present, perhaps but none was indicated in my XRF analysis. Maybe a trace amount. I have read people complain about this (filtering) in the forum before, but first hand experience really puts it in perspective.

Harold, I am confused with what you propose. I inquarted, made popcorn, processed the material with nitric/water, the result was mostly dissolved gold. I drained the silver containing solution and dropped a bunch of silver with some PC copper from that solution. Kept adding copper until it would no longer dissolve. Got out the right amount of silver I was expecting.

The brown material that was left in the reactor was washed with distilled water a couple of times. (Yes I dumped that water with the silver as I know it contains silver.) What I said before was that the original popcorn did not fully dissolve with the 50/50 Nitric solution. I had to add a few drops of nitric here and there until all the popcorn dissolved. I used my technical grade Nitric with distilled water I bought in my chemical supply place, on a 50/50 ratio as described throughout the forum.

The material in the reactor was then processed with AR as I would normally do with material containing 12% Ag or less, as I am assuming this material qualifies. So what I did was process the material with AR in several additions, boiled a bit at the end of the reaction. Once reaction was done, I added Urea dissolved in water until my solution stopped fizzing. I added Ice, filtered this solution to remove any silver traces. I added SMB dissolved in water to drop the gold. Filtered, for about a day. haha The last part was the issue.

Am I being concise enough or is there anything anyone would want me to elaborate? Pretty standard process I think... Or am I wrong? As I stated before the salts in the first post came from the water I was using.

Comments?

 

[lazersteve]

After filtering out the ice solution the liquid is where the gold should be (a simple stannous test to confirm).

You then add SMB and let the gold settle over night. Test the solution again for dissolved gold, if present add more SMB and repeat the settling process.

After the gold sponge has fully settled carefully siphon or decant off the barren liquid leaving the gold in the flask in which it was precipitated.

The next few steps are a variation of Harold's wash process for gold sponge:

Now rinse once or twice with water, letting all the powder settle between decanting and the second wash.

Now cover the gold powder with HCl and place a watch glass over the beaker top. Heat to a gentle boil on continue heating until the HCl no longer darkens.

Let cool, settle, and siphon off the acid testing for Au before properly disposing of the barren liquid.

I prefer a few final water rinses to flush out the last of the barren solution from the gold sponge.

If I suspect silver is still present (dark colored gold sponge) I also do a wash with warm ammonium hydroxide 10% and follow up with a few more water rinse/settle/decant cycles. Always swing the pH of ammonia solutions below 7 with HCl before properly disposing/storing to prevent exposive comppounds from forming if the liquid drys out.

At this point I begin drying the gold in the same flask it was precipitated in.

Once the gold no longer sticks to the flask when it is swirlled you are ready for either a second refining or melting. Melt a small sample and check for discoloration in the flux and/or on the surface of the button. If the button turns out shiny melt all of the gold sponge in a properly prepared dish. If the gold button looks discolored or crusty redissolve all of the powder and the button again in AR repeating the entire process for the highest purity gold.

Steve

 

[eeTHr]

chawimac---

If you want to know exactly how to solve your problems, then you should use exact terminology when describing what you have done. When something "dissolves," it goes into solution. Nitric doesn't dissolve gold. This can make people wonder what you actually did.

Avoid the use of urea, if possible. Instead, if you suspect left over nitric in your AR, after all your gold is dissolved, weigh a small bead of gold, and put it in the (heated) AR. If it dissolves, do another bead, and so on. When a bead won't dissolve any more, dilute the solution, chill if you want to, and filter the solution into another container (pick what's left of the bead out of the filter). Then precipitate.

When you are dissolving gold from inquartation, you can estimate the amount of SMB required pretty accurately, and use just a little bit more. Test the solution with stannous after the drop, to be sure none remains in solution.

If you don't want to wait for all the gold to settle, after the majority of it is on the bottom, siphon off the solution into another container and let it settle for a week. And process the gold that has already dropped. There shouldn't be very much gold in suspension, as it must be very tiny particles to suspend. The dirtier the AR, the more dark, tiny particles there will be.

When you rinse the dropped gold, bring it to a boil until until the rinse solution doesn't gain color. This boiling will also agglomorate the gold powder better, and you shouldn't have any problems with powders suspended in the rinse solutions, thereafter.

 

[chawimac]

eeThr

Thnx for the advice. Will try to be more clear.

Steve, great advice. I do appreciate.

To followup on the comments:
Why avoid urea? Some people suggest it. As far as a button here or there, it doesn't seem very practical. I am no refiner but I do 2 kilo lots in my little reactor. Some of this stuff may seem simple when doing 50 grams, but at a larger scale its very laborious. I know refiners are set up to process this easier, but I am stuck in the middle. Also, is ice optional? Is water to dilute enough to drop out the silver? I just feel I am not getting all the silver sometimes.

I XRF everything before I process, that way I know how much gold or silver to expect and how much chemicals to use throughout the whole process. I do not use SnCl, as I get all kind of weird colors. Haven't quite gotten the handle of it yet. I use a Hanna Redox meter. Pretty cut and dry. My SnCl gets greenish after a week or so.

Back to filtering the gold, it isn't practical to wait a week for this stuff to settle. Hehe I am poor, and I can loose my shirt speculating so long on gold! Process gold and wait a day to settle, then wash a couple of times, waiting for it to settle every time. Doesn't that take forever? There must be an easier way??? I will try the boiling of the gold to get it to agglomerate. Hope that speeds things up. I do appreciate the interest and help of all.

Thnx

 

[lazersteve]

Heating the gold after adding SMB will speed the settling process, boiling will not as the motion of the boiling liquid will keep things stirred up to a slight degree.

Settling for a full 24 hours can be avoided at the expense of some of the yields. You can allow the bulk of the gold to settle for 30 minutes to one hour, then pour off the suspension of fine gold particles that remains along with the gold that may still be reducing in the solution. The liquid that is poured off will contain a small percentage of the gold if you precipitate from pure solutions without base metal contamination. The more contamination in the liquid, the slower the gold settles and the more you will pour off with the solution when 'speed refining'.

Filtering with a buchner funnel and vaccum flask will eliminate the need for settling, but you will temporarily lose some gold to the filter paper. The paper can be burnt later to recover the 'lost' gold. Occassionally some of the finer particles of gold make it past the filter paper and you will need to filter more than once. A buchner setup is not in some peoples budget and has the added cost of electricity, filter papers, and labor. All to often you will find the vacuum process slows to a crawl and you'll be right back to waiting. There are some ways to speed the process, but you must weigh the cost in time and equipment verse the change in the price of gold.

If you are not in a race against time to turn the gold into money, patience can sometimes pay off with slightly higher yields and less equipment and labor costs.

Steve

 

[eeTHr]

eeThr

Thnx for the advice. Will try to be more clear.

Steve, great advice. I do appreciate.

To followup on the comments:
Why avoid urea? Some people suggest it. As far as a button here or there, it doesn't seem very practical. I am no refiner but I do 2 kilo lots in my little reactor. Some of this stuff may seem simple when doing 50 grams, but at a larger scale its very laborious. I know refiners are set up to process this easier, but I am stuck in the middle. Also, is ice optional? Is water to dilute enough to drop out the silver? I just feel I am not getting all the silver sometimes.

I XRF everything before I process, that way I know how much gold or silver to expect and how much chemicals to use throughout the whole process. I do not use SnCl, as I get all kind of weird colors. Haven't quite gotten the handle of it yet. I use a Hanna Redox meter. Pretty cut and dry. My SnCl gets greenish after a week or so.

Back to filtering the gold, it isn't practical to wait a week for this stuff to settle. Hehe I am poor, and I can loose my shirt speculating so long on gold! Process gold and wait a day to settle, then wash a couple of times, waiting for it to settle every time. Doesn't that take forever? There must be an easier way??? I will try the boiling of the gold to get it to agglomerate. Hope that speeds things up. I do appreciate the interest and help of all.

Thnx

Chawimac---

If you are doing large quantities in one batch, you should read this post by Harold_V. It addresses a few things which would be important to you, including a couple which you asked about.


P.S. People avoid using urea because of the reasoning that it's just an additional substance in solution, which might cause problems later, and it is unnecessary. For large quantities of Au in solution, use a larger button of Au. Just weight it before putting it in, and again after removing it, and you will know how much was dissolved into your solution, for subtraction of that much powder later if tracking the yeild is important. And it totally eliminates guesswork about the nitric content, eliminating unforseen extra steps. It's just a neater, more certain way of doing things, when you are concerned about time.