Where did my gold go?

[Oz]

It took 12 hours to get a milky brownish tan mud and his was a noticable black in a matter of seconds.My acid stayed yellow and his cleared instantly... :?: Thoughts anyone? :?:

Your brownish tan is dirty gold, your milky white is silver in solution reacting with chlorides to form silver chloride.

 

[2002valkyrie]

What should I do with it? :?: Dump it in with the rest of the mess?

 

[Oz]

This will get very convoluted receiving advice from multiple people at this point given what you have already done. I would suggest that you pick one person to guide you through this in private messages without distractions as too many cooks spoil the brew. The problem is that there is more than one way to solve this but trying more than one method at a time will not work.

I believe in the KISS system, keep it simple stupid.

As for you question on what to do with your current precipitate, the silver chloride you have made will not be affected by nitric, HCl, or AR, but will ride through the process and be saved so you can convert it to silver metal once again later. For now your focus should be on the gold you have invested in this process in my humble opinion. This is another reason I asked you not to throw out solutions or solids from this even if you “thought” they were worthless.

 

[eeTHr]

valkyrie;

After thinking more about your solutions situation, I would have to say that I think the copper cementing method has got to be the best place to start. The reason is that it will leave the copper (from the sterling) in solution, and thus keep it out of your way for the remaining steps. This follows the "eliminate the base metals first" rule, which makes everything else much easier and more efficient.

And doing it all in one big batch would take fewer steps. Your existing precipitate will go through the process OK.

When you decant the solution into another container (rinsing as mentioned before) after letting the copper metal work a few days (copper takes awhile), you will have only PMs precipitates (including the silver chloride riding along) left in that container.

Transfer the copper metal to the new solution container to see if any more comes down. It can still produce a little powder up to about a week later. When you're done with this solution, put some nails in it to drop the copper out. To further neutralize the solution for safe disposal, see 4metals' post at http://goldrefiningforum.com/phpBB3...40831&hilit=safe+disposal+of+chemicals#p40831

Then dissolve your precipitates in your manner of choice, evaporate accordingly, dilute, decant your PMs-bearing solution from the silver chloride (store the silver chloride covered with water), drop the Au out of the solution with SMB, and save the rest of the solution if it tests good for any PGMs.

Suggestions by others are always welcome.

Don

 

[2002valkyrie]

How do I know when I have evaporated the Nitric Acid off? Is there a good method? I figured Harold would have posted a method but I have not found it as of yet.

 

[eeTHr]

When you evaporate it down to the point that it starts to get syrupy, add a little HCl. If there is still nitric in it, that will make the nitric fume. If there is still nitric in it, add more HCl and evaporate it down until it starts to get syrupy again, and test it again with a little HCl.

If you only add a little nitric at a time until all the metals are dissolved, especially with a little heat, it usually only takes one evaporation. Some people don't evaporate at all when they do it this way, because all the nitric is consumed by the PMs.

Also, if you add a little sulfuric acid, about 1% of the volume of your solution only, it will drop any lead chloride (which you probably don't have in this batch, as it came from karat Au) and it will help to get rid of the nitric. You only add it once, at the beginning, because in won't evaporate except at much higher temperatures.

I evaporate mine at 190 degrees surface temperature, and turn it down to 140 or 150 toward the end, because once it gets down to a certain level it will spatter when it passes through a certain ratio of nitric to HCl.

Edits for errors: Adding the sulfuric drops the lead as lead sulphate, not chloride.

The spatter is due to the ratio of nitric, HCl and/or water. Apparently, at a certain ratio of these, the boiling point of the combination drops suddenly, and instant boiling causes the spattering. See link---
http://en.wikipedia.org/wiki/Aziotrope

 

[Harold_V]

How do I know when I have evaporated the Nitric Acid off? Is there a good method? I figured Harold would have posted a method but I have not found it as of yet.

Harold isn't willing to get involved in a fray such as this. Resolution for the problem is simple, but as long as opinions are posted freely, all my suggestions would do is continue to muddy the water.

Oz gave you excellent advice. That is to resolve this issue privately. While there are several routes that can be pursued, following the advice of one person, staying the course exactly as advised, is the wisest thing you can do. All too many readers have less than enough experience to understand the ramifications of some of the suggested procedures. There is an optimum method that can bail you out.

When you tested your supposedly nitrate solution and got a black reaction, that should have sent up a red flag for you. You have dissolved values in the first digest. That is where your missing gold will be found. Do NOT discard anything at this point in time. You can achieve what is, for all practical purposes, a 100% recovery, as long as you still have all of the material that has evolved from your various processes.

Harold

 

[eeTHr]

Harold;

While I took a cautious stab at it, I would certainly value your opinion over my own.

I think most people on the board would like to see how it should optimally be done.

Could you pleeeeeease give (most of) us a learning experience?

Sincerely,

Don

 

[qst42know]

Harold isn't willing to get involved in a fray such as this. Resolution for the problem is simple, but as long as opinions are posted freely, all my suggestions would do is continue to muddy the water.

I fold. Please lead on.

 

[2002valkyrie]

Once again, I seem to have embarrassed myself through this forum...
I halted all my procedures and realized I had problems when my 1st batch dropped too slow, too little and off colored. Then proceeded to start investigating with measurements including a stainus test in order to give the most information to the forum and try to turn a bad experience into a learning one, so that I might learn from my first blunder. As of from the time that I put the brakes on my processes I have only asked questions, gathered information and tried to process through it with as much common sense as possible. I have froze all my activity and will wait until I have found some confidence as I lost all of what little I had.
(Please understand the title of this thread was to get the attention of wiser minds than mine, I know the gold is still in a vessel in my work area and is recoverable) The questions are:
1) What can be learned from my ignorance?
2) What is the best way to come away with gold and silver without adding to my waste any more than is necessary?

This will get very convoluted receiving advice from multiple people at this point given what you have already done. I would suggest that you pick one person to guide you through this in private messages without distractions as too many cooks spoil the brew. The problem is that there is more than one way to solve this but trying more than one method at a time will not work

I would like to say; "As part of my quest to gain some confidence I have sent private emails from the beginning to a few intellectuals asking various questions and opinions."This public forum is just one way to get more attention to my embarrassment and answers to questions that are not answered in private as well as share my mishap so maybe others might benefit.

Harold isn't willing to get involved in a fray such as this.

I have only the upmost respect for Harold and only mentioned him as I know he has mentioned "evaporation of Nitric was his preferred method" but I have not read any specific procedures of his on the forum . And as much as I value his input, I also understand and respect his not wanting to be involved in this "fray" of mine. He is right to call it such. I have messed up and even though it's my embarrassment and frustrations that teach me the most, it is the harsh words of wiser men that cement my learning experience. And if he were to make suggestions as to what should be done. I would certainly take notes along with the educational criticism he sends my way. I know from reading the forum that there is no candy coating that goes with him, I respect that the most.
"I hope this offends no one and we can continue this thread with the best intrest of all Noobs in mind as I am the noobest Noob and value all of the brain power on this forum."

 

[Oz]

I doubt that you offended anyone, certainly not me. I understand that you were just trying to get all the information you could. My suggestion was because I was reasonably sure that this was your first precipitation attempt and the multiple processes being suggested differed significantly enough to cause you confusion instead of help.

It is good that you wish this to benefit others. Perhaps after you have worked through this with one of those you have been PMing with, you could report back the steps you took to resolve it.

 

[Palladium]

How do I know when I have evaporated the Nitric Acid off? Is there a good method? I figured Harold would have posted a method but I have not found it as of yet.

I'm glad i don't answer questions, I just post links for reading.

Harold has stated several times that he always added a button or small piece of gold so the excess nitric would be use up.

Here's a good conservation in the middle of another topic. :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=4674&hilit=evaporating+nitric+excess&start=20

And here's a different type process, but same principle.

http://goldrefiningforum.com/phpBB3/download/file.php?id=2899

Dissolving the Filings and Gold Mud With Aqua Regia

Place the filings in the same beaker as the brown gold mud, and add one (1) ounce nitric acid and four (4) ounces HCL for
each ounce of gold that you estimate is to be recovered. Filings will actually use more acid than the brown mud as they still
contain traces of base metals. Add the acid slowly to avoid the beaker boiling over. The idea is to add a small amount of the
acid mixture (aqua regia) and let it work, then add more. If all is added at once, the filings and fine gold powder go into
solution immediately, with a sure boil over. The beaker should be placed on the burner and allowed to boil at a low heat until
all the acid is used up or all the metal is dissolved. Don't use any more nitric acid than you need, as it must all be used up
before the gold can be recovered by precipitation. An excess of HCL does no harm, and insures all the nitric that is able to be
used up is used up as it reacts with the gold.

Evaporating the Gold Solution

Once all the acid is used up, or the gold is totally dissolved, take off the watch glass, pour in a little HCL to cool the solution,
then pour in a few drops of sulfuric acid. Be sure to stir with the glass rod all the time the sulfuric acid is being dribbled into
the beaker as it will want to flash to steam. Sulfuric acid is the method one uses to expel lead in solution. It converts it to
lead sulphate, which will be filtered off when the solution is filtered after evaporation. Lower the heat and allow the solution
to slowly evaporate. Do not evaporate too fast. Gold will be lost. After the solution gets concentrated, weigh a gold button
and record its weight on your tracking sheet. Slowly introduce the gold button to the beaker (DON'T DROP IT IN) using
tweezers. One should add some HCL at this point. The beaker should still be on the burner. If the button doesn't begin
bubbling shortly after it is introduced, all the nitric acid has probably been used up or expelled by evaporation. That is
unlikely. If no bubbling is noticed, evaporate the solution until it starts to thicken and leans towards a red color, then remove
it from the burner and add about four (4) times its volume of water to it to cool it. Stir it as the water is added as the gold
chloride will readily cool to a hard lump if it isn't diluted. You will need space in the beaker for wash water from washing
down the funnel and ice when you precipitate the gold, so don't use excessive water at his point.

You will more likely find that the button bubbles, as it is being dissolved, using up the free nitric acid. Keep it on the low
heat and add more HCL when the solution thickens and darkens. You will notice that each time HCL is introduced the button
starts the bubbling all over again. When HCL is added and it doesn't bubble, there is no longer any free nitric acid. Treat the
solution from this point just as above, removing it when it thickens and leans towards red in color. A cautionary note. When
the solution has gone too far in evaporation, gold will precipitate. As water is added, the solution will look something
like brass paint, in that small particles of gold will be noticed, suspended in the solution. Should that happen to the lot, put it
back on the burner and drop in a little nitric and HCL. Try to use a one (1) to four (4) ratio, as you are now building a small
amount of aqua regia to re-dissolve the gold that has precipitated. Repeat the evaporation as above, using excessive HCL to
insure total expulsion of nitric. One must evaporate the solution until it thickens somewhat, otherwise the free HCL makes it
difficult to filter. The filter paper wants to break through when the acid level is too high. About all that can be done when
that happens to you is to either dilute the solution with water or get it back on the burner and evaporate it all over again.

Harold

 

[2002valkyrie]

I'm glad i don't answer questions, I just post links for reading.

This sounds like good sound directions to follow once I get out of this pickle I'm in and start over. Thanks alot for the links, I like step by step proceedures and wish I had read this before, I would have noticed my problems a little earlier.

 

[Harold_V]

I didn't mean to come across as an old crotchety dude (although I am one) with my comments. The problems I mentioned are all too real, especially when coupled with an individual that deems it appropriate to tell those of whom he is asking advice only that which he cares to disclose. I've been through that on more than one occasion. I have no intentions of doing so again.

Clearly, that is not the case here, and I am not making any accusations.

GSP and I have, combined, probably 70 years of refining experience. He and I do not agree on many subjects----although I hesitate to say that either of us is wrong. I have my reasons for the position I hold, and I'm sure he has his as well. Both of us have refined more gold that most folks can hope to see in a life-time, each with acceptable quality.

The problems start when one asks advice and two (or more) methods are recommended, then the individual making the inquiry decides to pick from each, that which appeals to him/her for what ever reason. When things go south, it borders on the impossible to understand why, especially when the method suggested has worked flawlessly previously.

Yes, there are various processes one can pursue in recovering from an incident such as this. My procedure may be better, or worse, depending on many variables.

Here's what I'd do if this mess was mine. Lets start by determining that the material, inadvertently, was processed with AR, regardless of the best of intentions. That means that everything in the alloy except silver has been dissolved. The silver would have been converted to silver chloride, which should be expected.

My logic in this case is simple. I'd recover all of the dissolved values without attempting to recover any of the base metals. Therefore, zinc is out. As has been suggested by more than one individual, I would recover the dissolved values on copper. I would use pieces of copper that present a large surface area to the solution, and I would leave the copper in the solution until the solution checks barren with stannous chloride. I would then remove the copper and wash each piece carefully, recovering all traces of the black cemented particles, which are the values.

To address the silver chloride, I would have washed it well with water (tap water is fine--it is already a chloride---what possible benefit one would gain by using distilled water?), combining the wash water with the solution that was cemented with copper, above. The remaining solids I would then reduce to elemental silver, using scrap iron or aluminum. It's important that the conversion be accomplished with metal, so traces of values, which are sure to remain in the silver chloride, will be recovered as well.

When the cemented values have been well washed, I would incinerate them, to insure that there are no chlorides present. I would then process in nitric, to eliminate any traces of base metals that have hitched a ride. The results should be relatively pure gold.

I would incinerate the silver, which would have been recovered with metal, then I would process it with nitric, which would yield the traces of values that likely got included with the silver chloride. I would recover the resulting silver nitrate with copper. I would add the traces of vales to the gold from the previous digest, at which time I would dissolve the solids, evaporate, filter, then precipitate.

In this particular instance, while evaporation has been discussed as a method of eliminating nitric from the original digestion, that is not a good idea, nor is it required. Evaporating solutions that are heavily contaminated with base metals can be troublesome, especially when a serious amount of silver chloride is included. When it has been determined that a process has gone awry, it is usually far better to get back to square one and start over than to attempt to live with the problems. A total recovery would be using scrap iron or zinc, cementing down all values, along with copper. In this case, it's clear that recovering the copper will serve no useful purpose-----therefore using copper (for cementation) is the wisest choice.

2002valkyrie , you asked about starting over, using aluminum. Unless you have more experience in refining, I suggest you avoid using aluminum. It presents more than a lion's share of problems once introduced to your solutions. They can be handled, but it may not be apparent how, or why. If you find yourself in trouble and must start over, consider copper first, then iron (steel, not cast iron) or zinc.

Harold

 

[eeTHr]

Harold;

Whew, thanks very much for posting. Your wisdom, time, and effort is a great help, and much appreciated!

The remaining solids I would then reduce to elemental silver, using scrap iron or aluminum.

What type of solution should the silver chloride be in to do this?

I'm getting that in this particular case, with mainly just silver chloride present, the use of aluminum would not present the problems which you mentioned in your last paragraph, as one would be "done" with the solution afterwards anyway?

Don

 

[goldsilverpro]

Good post, Harold. Pretty much the way I would do it, also.

 

[2002valkyrie]

To everyone reading this post,
I have researched all my options and though many of you have offered good advise, I have decided to take some and handle this blunder through the private messaging route in hopes that I will not only resolve my problems but also learn a little more in depth as well as hopefully gain a friend. I will hold back my posting until I can post in full my route to recovering my pm and also refined it as I intended to. As for the intellectual that is helping me, they must authorize me to disclose their identity.
Until I post again, Thank you all for your concern and advise.

 

[2002valkyrie]

I have decided to take some and handle this blunder through the private messaging route in hopes that I will not only resolve my problems but also learn a little more in depth as well as hopefully gain a friend

Well maybe not I have tried to use the P.M. feature so many times. I'm tired of typing the same thing over and over. There is an issue with the P.M. feature.

 

[Harold_V]

The remaining solids I would then reduce to elemental silver, using scrap iron or aluminum.

What type of solution should the silver chloride be in to do this?

All of my experiences with silver chloride were handled with a water and HCl solution, the sole exception being the silver chloride that was recovered in the furnace.

In the case in question, I would have rinsed (with tap water) the silver chloride a couple time, to remove the majority of contained values, then I would put the material in a vessel that can withstand heat (from the reaction), covering the material with water, then adding about 10% more in HCl. I would then introduce scrap aluminum (or scrap steel). I used aluminum because I had an abundance, and was willing to deal with the problems (inability to filter until well rinsed).

I'm getting that in this particular case, with mainly just silver chloride present, the use of aluminum would not present the problems which you mentioned in your last paragraph, as one would be "done" with the solution afterwards anyway?

The problems are real, and they persist when reducing silver chloride. The one advantage is that you can rinse the resulting material endlessly, allowing the solids to settle well, then decant by siphoning. That leads to considerable confusion, because the solution now appears much the same as the resulting silver, so you have the never ending question of losing silver, or not. My experience indicated to my satisfaction that none was lost, that it was the aluminum that created the appearance.

Once well rinsed, the resulting converted silver will filter perfectly well, but it's very important that you rinse several times before attempting to filter.

If you have any doubts, use scrap steel. Nails cost too much, and they aren't really the best choice because in the end it's required that you remove any unused metal. Starting with sheet material, presenting a large surface area, is best. If one scraps computers, many of the covers are made of steel that is not painted. It's perfect for the job. Any traces can be dissolved with HCl after the converson has taken place. That is one of the reasons I chose to use HCl in lieu of H2SO4. There is no risk of dissolving any of the converted silver.

Be cautious of using pieces of scrap steel that are quite thick and heavy, for you will be inclined to break the vessel in which you are making the conversion. The silver chloride should be stirred on a regular basis, so all of it comes in contact with the scrap material being used to make the conversion.

Harold

 

[eeTHr]

Harold;

Thanks for the very detailed explanation. There are so many things that can happen when trying a new process, that it really helps to know ahead of time what to expect, and what to avoid. 8)

Don