Clear crystals in AR solution

[Mcnew32(Ag)]

Need a little advice please. I recently dissolved some gold foils from pins with AR then I neutralized the excess acid with urea, filtered the solution and it's been sitting a couple days in my garage. When I came home today there were clear crystals in the solution. My question is can I just filter the solution again remove the crystals then add SMB to drop out the gold or should I add water to dissolve the crystals again then drop out the gold?

Question number two, in the second picture you see how dark the solution is? This solution is from dissolving about 2,000 blood sugar test strips in AR. After being filtered I set the solution aside for later processing of more strips. I noticed today as well the solution has turned a lot lighter in color. I am just wondering what this is an indication of.

 

[butcher]

CH₅N₃O₄
If you had a lot of nitric acid in solution adding urea, these salts could possibly be urea nitrate , a high explosive, when mixing nitric acid and urea, this is one good reason not to use urea, that and the fact that urea does not destroy nitric acid, it will help to remove the gases from nitric acid, but not the acid itself which can make urea nitrate.

Using urea is not only dangerous in my opinion, but will not work if you get heavy handed with the nitric acid when making aqua regia, as you will not only have the NOx gasses for the urea to deal with but free nitric acid which the urea cannot deal with, except to convert to urea nitrate in the solution...
urea is also organic carbon based chemical, not something I want mixed in with my refined gold solution...


You should learn other methods which will work better, like not using more nitric than needed, evaporation to drive off nitric and its gases, using gold to consume excess nitric, and sulfamic acid to destroy the nitric acid...

I would not heat that solution to attempt evaporation, even in solution that could possibly become a very dangerous situation. adding water to dissolve the salt crystals would be much better and safer.
A stannous chloride test, or a test with a copperas crystal can be helpful to see if the gold can be reduced easy enough with your chosen reducing agent (to see if you have removed the oxidizer from solution enough to be able to reduce the gold).

 

[Grelko]

In question two, after the solution got lighter, was there any powder at the bottom? Were the test strips clean or previously used, because any blood left on them would contain iron.

 

[Barren Realms 007]

In question two, after the solution got lighter, was there any powder at the bottom? Were the test strips clean or previously used, because any blood left on them would contain iron.

I doubt the iron from the blood would have any effect.

 

[Mcnew32(Ag)]

No there isn't any precipitation of any sort in the bottom. Most of the blood was removed when the covering was removed to expose the gold underlay. I used AR to remove the gold and heated slightly. There is residual clue left on the strips tho. Most of the glue was removed with googone. After washing then I put into AR. But after gold was removed and I sorted through the strips I could see some residual glue left in the strip. Other than that nothing.

 

[Mcnew32(Ag)]

For the solution with the excess nitric, should I cut the solution in half, dilute the solution with water dissolving the crystals then heat solution to drive off nitric then test with stannous? Or should I filter off the solution catching the cystals in a filter then heat solution and drive off excess nitric?

 

[Geo]

Use sulfamic acid. Sold at The Home Depot http://www.homedepot.com/p/Custom-Building-Products-TileLab-1-lb-Sulfamic-Acid-Cleaner-TLSACRA1/100171510 It will remove the excess nitric acid without creating dangerous byproducts. Warm the solution and add the sulfamic in very small increments or it can cause a boil over. The nitric is driven off as NO2 and N2O. Do not breath these fumes. Stop adding when you get no more reaction.

 

[butcher]

Do not use heat to evaporate solution to decompose the excess nitric, with urea nitrate being a possibility of the source of crystals, doing so could become a dangerous situation, that and evaporation may just make more salt crystals of urea nitrate if that is what these crystals are.

Diluting solution will not hurt, and can dissolve water soluble crystals.

Testing for gold in solution with the stannous chloride test, or the copperas (ferrous sulfate crystal), can give you a clue if you have excess nitric acid in solution, to see if the gold is easily reduced by a reducing agent,, if you know for sure there is gold in solution and the test shows negative, or shows positive and then goes negative, nitric is oxidizing the reduced gold, or keeping the gold from being reduced in the test, this excess nitric will also give you similar problem if trying to reduce the gold with a reagent like sodium metabisulfite, copperas...

If there is still excess nitric acid Harold's method would be a good way to deal with excess nitric at this point, adding gold to consume excess nitric in solution, just keep enough free HCl in solution for the reaction to complete, gentle heat can help, and you can keep the salt crystals from forming with additions of HCl if needed during the process.

 

[MarcoP]

After you diluted the main liqueur to put back in solution eura salts you could use a solid copper bar to kill the free nitric and cement the gold out. After a good wash in HCl, I would dissolve the settled powder in HCl/Cl and use copperas to reduce gold free from copper. Dilute and boil to make powders cling together and settle faster.

Marco

 

[Mcnew32(Ag)]

Thank you for the help guys. I appreciate it. I will slit the solution into two different beakers dilute both then add sulfamic to get rid of excess nitric. The test for values.

 

[Mcnew32(Ag)]

Here's what it looks like after it has been diluted, crystals dissolved and heated to evaporate excess liquid and acid. Once I get it evaporated to a thick sludge I will add water and begin dropping the gold out of the solution.

 

[Mcnew32(Ag)]

This is a follow up question to my previous post. I have since neutralized the excess nitric with clean copper pipe. After I filtered the solution I tested the remaining solution for value as most of the gold was cemented out using the copper. I used a piece of paper towel to text with stannous. The solution is a deep blue color from dissolved copper so the papertowel piece was blue. When I used the stannous the drops turned yellow in color. I was wondering what yellow meant.

Also I was planning on putting the filter and cemented mud into AR and just re dissolving the mud. This would be the best way am I correct?

 

[Geo]

That stain could be a PGM but it would be a minute quantity seeing as you cemented everything of value out on copper. Why are you adding base metal to a gold bearing solution? Even though the nitric is consumed in the process, it is basically just a cementing values out of solution on copper. There are people I have talked to that use that as the final process. If done correctly, the cemented gold can still be pretty pure, up to 99% pure from what I've read as long as there's no PGM's involved.

I would use HCl and bleach to redissolve the cemented powder.

 

[FrugalRefiner]

Mcnew, first, get that nice chainsaw away from your chemicals or it won't last long.

I'm not sure which previous post this follows up. Let me know, and I'll merge them to help keep the information together.

Dave

 

[Mcnew32(Ag)]

This is following up in the white crystals in the AR solution post. I since then diluted the solution evaporated it down to a sludge then diluted again and used copper to use up the rest of the acid. I have quite a bit of brown mud in the filter.

 

[FrugalRefiner]

This will probably sound harsh, but this post is intended to help you and others.

Several posts above, butcher mentioned that he was concerned you may have urea nitrate crystals, and that it could be dangerous to use heat to evaporate the solution, but that diluting might help dissolve the crystals. A few posts later, you showed us the result of diluting the solution, then heating and evaporating it. I'm not sure what you were trying to accomplish by diluting the solution, only to heat it and evaporate it, and it seemed to ignore butcher's advice.

In your most recent pictures, you showed your solutions right next to your chainsaw. The fumes from these solutions will destroy anything made of metal. That's why you need a dedicated space to do this work. In the picture with the chainsaw, I see several liquid splashes on the floor, so it's now contaminated with toxic waste.

In your second picture, you have your wet filter paper sitting on what looks like a piece of raw OSB. It too, is now contaminated with toxic waste.

You need to "clean up your act", literally. Whether you're working out in your back yard, or an old shed, or a dedicated refining space, you have to think about lab hygiene. That starts with working on surfaces that will not absorb a toxic solution if you happen to drip on it. Keep everything not related to recovery and refining away from your chemicals. Maintain good ventilation. Think safety first.

Dave

 

[butcher]

As FrugalRefiner stated in an attempt to help you, safety needs to be on the top of your list of concerns.
From what I see so far, in the pictures, it make me suspect iron was involved in this solution, I am unsure where the iron came from, or if it is even involved, iron can resemble gold in several different ways, Hokes book page 100 gives some information on iron, and help with identification and testing for iron in solution.

The filter looks full of an iron hydroxide, did you have iron involved in any part of the processes?
The yellow stain in your test may also be from iron.
The color changes in your first post could also be a reaction of iron.

Up to this point I do not see anywhere you proved to us or yourself that you had gold in solution, so at this point your still just guessing you had gold in solution, which if so has been cemented out of solution in the brown iron looking mud or sludge.
I still suspect iron, cemented gold would have a more blackish look to the powder, if there was gold its cemented black powder may be mixed in that sludge in your filter.

If you were going to cement any values you may have had in solution by using copper as a displacement reaction, removing nitric would not be needed (unless of coarse you were trying to conserve on how much copper you were going to use), but being conservative on your nitric use in the beginning would have been a better choice.

Mcnew32(Ag),
What I see, is you have learned just a little about what you think may work, it also appears you are getting misinformation in what you have learned up to this point, now your trying what you think you have learned, but what I see is you are just trying things in the dark, without an understanding of anything your attempting, this will just lead you from one problem to the next, spending your time trying to solve problems you create through ignorance, this may help you learn to get out of a mess or a bad situation, but it will not help you learn how to recover or refine precious metals with the best use of your time energy and money, the first step should be to educate yourself, in the safety and to gain an understanding of these processes your are attempting. study of Hokes book and the forum is the help you need, to help yourself, asking questions of how to get out of one mess so you can get into the next mess is not going to help you get very far in this field of work.

I suggest the best thing you can do is put up your chemicals and get out Hokes book, and study the forum, when your ready to begin using the chemicals, I suggest using them in doing the getting acquainted experiments in Hokes. this in my opinion would be a wisest place to start, and put you the closer and faster towards getting that pure gold in your melting dish (and doing so safely).

 

[Mcnew32(Ag)]

I know that you guys are very concerned with health and safety of the member here on the forum. I do not do my processing in the area you seen in the picture. The solution and the filter was after the reaction was done and safe from any kind of fumes at all. This process started with a little over 3 lbs of various pins and gold plates pieces off of various boards. I did take a magnet to the pins and there were some iron bearing pins but not enough to worry. I got tired of boiling the pins in HCL and decided to just finish with nitric. I ended up adding a little to much nitric acid. There were plenty of gold foils and hollow pins. Also dissolved a 1 gram gold button in the solution to try and use excess acid. Still too much acid. So I just used copper to displace the gold. I normally just process foild from fingers and ceramic CPUs. Thought I'd try the gold plated material and pins. So far not going so well ha. Doesn't help that sometimes I have to leave my solution sit for a couple days before I can get to it again and that's when all the precipitation occurrs and crystals form.

 

[Vidya]

Have you recovered the gold, I am facing same issue please reply.