Gold will not fall out of HCL/CL

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Bobby835

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Joined
Oct 5, 2014
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1
Gold will not precipitate.

Over the past few weeks I have successfully precipitated gold out of my HLC CL solution 3 times with SMB I processed small amounts of fingers these three times. I was confident that I had the process down, so went all in, and put in 150 finger sticks.

I soak them in HCL peroxide and filter out the gold foils, on this final attempt I had so many gold foils. 4-5x what I had in the previous three attempts, so is there gold in there? I have very little doubt. (I know I need to test the solution, but my test chemical will not be here for a few days)

Then I take those foils and resolve in the HCL/CL wait 24 hours and then precipitate...the past three times were text book, all reactions perfect, however with this third time I did things slightly different on this step....I started to heat the solution, because I thought I would just boil off the CL instead of wait 24hrs. After heating I noticed a foil that had not dissolved so I decided to add a little more CL to finish what I might have missed...and I thought I would just wait the 24hrs this time. So I waited 20 hours and decided to heat it for 10 min to make up for the four hours.

That is what I did different. When I went to precipitate, the solution went from the yellow/green color, to clear. It never turned brown. There is a very light dusting at the bottom of my beaker, but far far less than my practice rounds.

Has anyone ever had a solution lock up like that, and not drop your gold. What can be done to correct this?
 
When your yellow solution is clear after the precipitation, your gold is elemental now. To be sure, you've got it all, test! If you do not have stannous yet, wait until you have some.

It is completely impossible to know how much gold it is, before you have weighed it. Sometimes it looks like 3g and in the end you only got 1g or (seldom) the opposite and you have double as much as you believed.

Gold precipitate from very diluted gold salt solutions can be that fine, you first will see it the next day. What was your starting material and how many gram? How much solution did you precipitate from?
 
Making small changes, such as using heat, can change things, sometimes drastically. Being pretty new myself I try to follow guidelines that have proven successful for me especially anytime I try it on a larger scale. Solar Plasma has give good advice, test your solution before disposing of it. And usually when a solution goes clear, your gold has dropped. I would add, let it sit for a few days, undisturbed, and see if it settles a bit more out. Use the time to study some more, it will be helpful in the long run. Get your testing materials together, take this time to understand how they work as well. I like the testing steps, it not only confirms things are going right, I just enjoy watching the color change during the testing. Having all the needed materials up front, before starting anything, is very useful and will help you avoid many mistakes.
 
Without stannous chloride test solution and gold chloride test solution, you just don't know for sure if you have left values behind or not.
 
Bobby, put some tin solder in a small vial of HCl. This will make Stannous Chloride and allow you to test your solution for gold.

Jon
 
Hi !
Was this batch of fingers from a different load of equipment? If so, could be that the gold plating was very thin compared to the last ones.
You mensioned the color was yellow/GREEN. Grean can indicate that you failed to remove all of the base metals from the foils. That would mean that you're dropping gold from a dirty solution which can have a great effect on the process.
Don't start getting in a hurry! Hurrying and trying to do things before you should is good when you're sitting waiting for a freight train to finish crossing the road, not good when processing precious metals.
You can search "how to make stannous chloride." sporting goods stores have bags of fishing wieghts that are 100% tin.
Finally! If the solution has set for a while, mix just a little SMB with a very small amount of hot water and add it now. see if you get a drop. Test your solution after the drop.
Good luck! artart47
 
I always make a practice of testing the turbidity of the solution after a drop that didn't seem right. The solution can look pretty clear and still have your gold floating around in it. Use a bight flash light and shine the beam through the solution. It will show you the clarity of the solution. Any cloudiness could be (operational word being "could") fine gold powder that has not settled. A gram of ultra fine gold powder will stay suspended in concentrated acid for quite some time.
 
As long as when you heated the solution you did not actually boil it, you should not have lost any values. Does not take a very high heat to vapor off the CL. Sunlight for a few hours will also do the job as well as just letting it sit for a day or 2.

Like Geo said, real fine gold powder can stay suspended for a long time. Wait a day or 2 for the solution to settle. I've had it go completely clear looking with little to no precipitate on the bottom, and 2 days later a very fine black dust covered the bottom of the beaker.

And as someone said make your own test solution by putting in small bits of some 95/5 tin/antimony or tin/silver solder in HCL and when it dissolves you have a good test solution to use. It will go bad over time so adding some more solder every so often will keep it fresh. (Note the antimony or silver will not dissolve and leave a few bits of gray bits in the bottom, perfectly normal.)
 
Stannous chloride is a great reagent to test for gold in solution, it is not the only tool out there.

Pretty green crystals of ferrous sulfate are easy to make, as long as you have some dilute sulfuric acid and a source of fairly pure soft Iron (like from your electronic scrap transformers), you can use the copperas crystals in a multi well spot plate or even with a white plastic spoon, or two, to test for gold in solution, or use the copperas to precipitate gold from solution...

Ferrous sulfate crystals in the spot plate are also very useful for testing gold where you may have other precious metals in solution with your gold (like when working with dental gold), and you wish to remove gold in one test (for gold), that may mask the color of another precious metal in the test), of the spot plate well, and move the now gold barren solution to another well to test with another reagent (like SMB) for another precious metal in solution...


The spot plate is a handy tool, and using it with a combination of reagents can be a tool that can help you in knowing where the precious metals are at, or where they are not, (in solutions).

A black spot plate is handy also, (I haven't found a porcelain multi well spot plate yet), but black plastic spoons come in handy for me, with testing for silver in solution with a chloride salt or a drop of HCl, the white cloud of the silver chloride in the test shows up easily against the black background of the spoon.

Harold has made many posts related to using this valuable tool for testing for more than one metal in solution, Reading and studying his posts, can put precious metals back into your pocket instead of your waste bucket.
 
Something I still don't understand is why we use copperas crystals in a spot plate but we mix copperas with water and hydrochloric acid to drop gold from the main liquor. This thought also come with a doubt, if we have enough free HCl and the main liquor is already diluted, could I just use straight crystals?
 
From what I have read, and this is because I've never used the crystals, is the crystals are better for testing in a spot plate. Again from what I have read, it makes a ring of yellow, elemental gold around the edge of the test sample.
 
Thank you Geo, on my readings I've also noticed that we should use enough crystals to drop all gold in the spot plate if we want to be able to test for remaining PGMs in solution and this is what confuses me the most. In a spot plate straight crystals are able to push all gold out of solution but why can't this be done in the main liquor? That's what really puzzles me. Moreover after days of searches I still couldn't come up with an answer on my own and even Mrs Hoke does the same think (crystals in spot plate but mixed prior addition in the main liquor) but doesn't gives any clue on why.

I mean, I understood that's the way it works, probably a better visual effect in a spot plate but would be a plus understanding why straight crystals shouldn't/can't be used in the main liquor, or the other way around, what's the cons in mixing with water and HCl.

This became the most hunted answer of mine. I never took so long to find the correct answer when having a specific question in my head.

P.S.: probably off topic, apologises.
 
Bobby835 said:
Gold will not precipitate.

Over the past few weeks I have successfully precipitated gold out of my HLC CL solution 3 times with SMB I processed small amounts of fingers these three times. I was confident that I had the process down, so went all in, and put in 150 finger sticks.

I soak them in HCL peroxide and filter out the gold foils, on this final attempt I had so many gold foils. 4-5x what I had in the previous three attempts, so is there gold in there? I have very little doubt. (I know I need to test the solution, but my test chemical will not be here for a few days)

Then I take those foils and resolve in the HCL/CL wait 24 hours and then precipitate...the past three times were text book, all reactions perfect, however with this third time I did things slightly different on this step....I started to heat the solution, because I thought I would just boil off the CL instead of wait 24hrs. After heating I noticed a foil that had not dissolved so I decided to add a little more CL to finish what I might have missed...and I thought I would just wait the 24hrs this time. So I waited 20 hours and decided to heat it for 10 min to make up for the four hours.

That is what I did different. When I went to precipitate, the solution went from the yellow/green color, to clear. It never turned brown. There is a very light dusting at the bottom of my beaker, but far far less than my practice rounds.

Has anyone ever had a solution lock up like that, and not drop your gold. What can be done to correct this?
Click to expand...


Sounds like you still have chlorine in soulution as you said you added bleach then only heated for 10minutes. Do this test: Hold a 1/2 capful of ammonia over your beaker, IF the beaker starts releasing a vapor you obviously have free chlorine in solution. If so that is the issue its re-dissolving the Gold, so run a fan over the solution to blow away the chlorine takes about an hr. Then re-test with the ammonia again, when it stops producing any vapors it should begin to start dropping on its own since you already added SMB.
Been there done that, hcl/cl takes patience & a lot of stirring & muct stay covered at all times with cling wrap.
If no vapor then add a bit of hcl as your ph may be too low etc...
Dave
 
Haven't used copperas myself yet but when you think of it...

It's easier to spot a ring of gold around the crystal in the spot plate than a thin precipitate.
It's easier to dissolve copperas in water without being covered in precipitated gold and you can filter off garbage from the copperas solution before mixing it with your gold chloride.

Göran
 
HI,
Maybe, because the "liquid copperas" will get in contact with all the "liquid" AuCl much easier with stirring, then to get the crystals to "touch" all the liquid AuCL.
Just my thought, I am a bit tired , so maybe I didn't use the right words, but I hope you understand what I tried to say.
Also like g_axelsson said, " you can filter off garbage from the copperas solution before mixing it with your gold chloride "

greetings

Pattt
 
Yep, I see it now. Something I've probably missed was the needs of filtering copperas before mixing it with the main liquor. I believe I've got the whole picture now.

Thank you guys.
 
I use copperas exclusively. I don't see an advantage from dilution or crystals, at least not relating to effectiveness.
I currently use the hi yield product. It has inpurities but works as well as self made. When i make it myself, it is filtered and also works great.
The only percieved benefit with dulution or crystals that i have noticed is that if you have pms stuck to base of vessil, a small crystal thrown in will lubricate things and movement returns.
I've tried smb, find it costs more and don't see the benefit. please, by all means, if i am missing values with copperas let me know.
 

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