SSN leaching. I need help for the neutralization and precipi

[Stowmaster]

To test, I used the one piece 486 processor. It was dissolved in a mixture of 7 volume parts 25% rock salt and 1 volume part 65% nitric acid. I need help with the choice of the means to neutralize the excess of nitric acid and precipitation of gold.
I have in stock:
1 Sodium hydroxide
2 Sodium bicarbonate
3 Sugar (theoretically with nitric acid forms oxalic acid, which precipitates the gold).
4 Carbamide peroxide
5 Magnesium Chloride
6 Sodium metabisulfite
7 Sodium thiosulfate
8 Iron (II) sulfate
9 Oxalic acid.
10. Аmmonium hydroxide

I have no urea, but I can buy it. But I need to buy to go to another city. Or by mail order 25 kg bag.

Please help with the choice of reagents.

 

[butcher]

Nitric acid and its compounds can be driven off with heat, evaporation, you will read of the process in Hokes book (of 3 evaporations with additions of acid, normally a few drops of sulfuric and HCl to wet when using Aqua regia), evaporating to syrup, but not so far as to form salts in solution (even though Hokes book used the word boil to describe the process, the solution is not ever brought to an actual boil, which would cause lose of values, Note that in C.M.Hoke’s book She was using a steam bath to do evaporations on which would not actually bring solution to a boiling temperature, but would be below a boil to evaporate solution.

If you have not read Hokes book you need to do so, if you expect to get a good understanding of refining gold.

Since you have a high salt content (brine) already, with high sodium content, it will be a little more challenging to get the job done without forming salts or evaporating them to crystals, but it can be done, this will be a little different from the normal aqua regia, because of the higher NaCl content, you may also have to evaporate, to syrup more times re-wetting with a little acid a few more times than normal, because of the higher salt content (tending to try form crystals before all of the nitric compounds are removed).


(I will speak of just using sulfuric acid here, but If you Have HCl it can also be used here, as described in Hokes book, with a little H2SO4 as described).

Because of the SSN and Nitric Brine leach solution used here, I will look at doing this process with just using sulfuric acid (where HCl can be used also), I would add a little more sulfuric acid than I normally would, this will help to keep salts from forming, upon evaporation, the sulfuric will help to form HCl from the salts in the brine solution, when evaporating off nitric oxide gases, if base metals are involve they will form sulfates dissolved in solution, lead or silver would form insoluble sulfate salts, some very little silver may stay slightly soluble in the concentrated chloride solution, until it is diluted later, you could drive off some of the HCl formed when evaporating, HCl would pretty much begin to leave solution after most of the HNO3 and its compounds, Here the sulfuric would form more HCl from the brine solution (this HCl formed will keep gold dissolved in solution), sulfuric acid does not evaporate at the temperatures involved (unless evaporated dry and the salts were roasted at high temperatures, unless you drove off all of the HCl (that is formed from NaCl and H2SO4), from this solution gold will stay dissolved in the HCl.

Ideally I would not want the sulfuric acid used to be too dilute as this added water which would need to be remove with the evaporation process, where water evaporates before HNO3 from solutions, although you could use 32% sulfuric acid (car battery acid) as it would just take a little more time in the process to remove added H2O after each addition of acid.

After removing nitric acid and its compounds with the evaporation process, you will want to dilute the solution with 3 to 4 parts water, let it sit (overnight), the insoluble salts, silver lead and other trash will precipitate, and solution will clear, decant and filter solution which contains the dissolved gold to clean jar, do not disturb insoluble powders, Now you can precipitate gold with reagent of choice, Sodium metabisulfite would be my choice from your list above.

 

[golddigger2]

To help drop the lead and other trash you can add some reagent grade sulphuric acid 10 to 20 mls is enough. Put in a handful of ice cubes and let sit overnight this will drop any lead out of solution and allow it to be filtered off

 

[rickbb]

Sulfamic acid will remove excess nitric and create a small amount of sulfuric to drop the lead at the same time.

 

[bmgold2]

Nitric acid and its compounds can be driven off with heat....(even though Hokes book used the word boil to describe the process, the solution is not ever brought to an actual boil, which would cause lose of values, Note that in C.M.Hoke’s book She was using a steam bath to do evaporations on which would not actually bring solution to a boiling temperature, but would be below a boil to evaporate solution.

How does boiling cause lose of values? Would heating the SSN leach itself until it is bubbling/boiling be my problem with my tiny testing with the Gold Hunter's Test Kit? Could that be causing the leach to lose the nitric and then make the leach NOT WORK?

I have just about given up on leaching gold and went back to normal gold prospecting. In fact, I just yesterday found one small speck of gold from a shovel full of normal masonry sand in an attempt to calm my fever. It surprised me that there was any gold at all considering I'm in Pennsylvania in an area with no KNOWN gold. Anyway, I still want to figure out what I am doing wrong with the test kit since it would be a nice kit to use when testing rocks if I ever figure it out.

bmgold2

 

[butcher]

vaporization:
http://en.wikipedia.org/wiki/Vaporization

Evaporation:
Evaporation gases of fluids slowly leave the surface of a liquid, this will happen below the boiling point of that fluid.
http://en.wikipedia.org/wiki/Evaporation

Boiling
Boiling is where gases decompose at the bottom (from a higher heat than that used in evaporation), the gases decomposing at the bottom of the vessel rise to the surface where they reach the surface, the bubble can pop violently and splash liquids (containing ionic salts of metals) this can splash the metals out of solution, or carry them over when distilling.
http://en.wikipedia.org/wiki/Boiling



I doubt this was the problem with the gold leach test, I would be more likely to think the leach was just struggling to get any gold ion into solution or keep them there.

I live in a very rich mining area, with many gold mines within walking distance, lots of abandoned hard rock gold mines, that were not mined out, most of the mining stopped not because the mines ran out of gold, but because the price of gold could not pay for the labor or cost to mine the gold, or because during the world war, all miners by law were forced to mine more important metals for the war, even today these mines would cost a fortune to mine, and with all of the government regulations or opposition to mining by environmentalist groups these mines will not be opened to mining any time soon.
you can still get a little free gold at most any of the rivers or creeks around here, a few speck of gold in most every pan, but even then that rarely pays for your time, or equipment (to move enough material),to do any real mining, you have to move and process a lot of rock, anymore it is only done on a very small scale more as a hobby, or recreationally mining, again because of government regulation, the days of mining on large scale, large groups of men or equiptment or large companys mining gold, and pulling millions of dollars worth of gold out of the ground, are just about gone, there are a couple of small mining company's here that are struggling to survive, but even those are being phased out, or shut down, being limited to what they can do.

When the government says you are polluting a river if you pick up gravel from the bottom of the river, and drop that same gravel back down into the river, it makes it hard to mine any gold, with them limiting how much material you can move to get that gold, or what type of equipment, or operation you can use, it puts mining out of business, or makes it impossible to mine on the scale that is needed to make it profitable, it cost a lot of money to process a lot of rock or gravels to get that gold, tons of material need to be moved and processed, to make it worth while.

If we mined like they did in the past young kids would make more money breaking rock for 16 hours a day, but we do not, and these young kids make money working at burger king cooking Hamburgers (probably for more money than they would get for mining gold, and probably doing easier work than they would at breaking rock all day).

Gold is still in them there hills (they may have got most of the easy stuff out of the rivers and creeks), but it takes a lot of equipment or manpower to move enough rock to make it profitable, real mining is large scale operations, and with the government and special interest groups blocking the ability to mine, you are better off working at McDonald's flipping burgers than trying to mine gold for a living.

bmgold2,
Forget about testing Ore, you are just wasting your time.
Spend your time on learning to test metals, learning the value of the metals.
Spend your time mining where the gold or precious metals are around you, learn to test for buy, to determine the value of scrap,learn to buy and sell jewelry and other scrap learn to mine your area (urban mining).
Fix you yourself up a test kit, learn to prepare your own test solutions, and how to use your kit.
Then you can go to town mining for gold.

 

[bmgold2]

Although I would love to make money at finding (buying or mining) gold, right now this is more just a hobby and I'm trying to prove to myself that this test kit that I bought actually works. So far I am not having much luck. Maybe I did waste my money and time on this test kit. Maybe I'm doing something wrong. I really want to know which is right.

Since the kit did not come with any test ore to prove it works and to show what I am supposed to expect, I can't say if it actually works or not. It will dissolve gold if there isn't anything else mixed with it (except the small amount of copper in the karat gold I used as a test). When other things are included with the material, it hasn't been able to dissolve the gold. That must mean that the kit is not useful for testing ore.

I still want to get a good test of the ore I bought. It's not about making money...It's about proving I can do it. I don't even expect to recover gold from it but a nice purple stain on a paper towel would do (for now).

When it warms back up, I want to go out prospecting for gold again. I don't expect to make any money at it but I enjoy finding it even if it is only a few flakes in a bottle. There's always a chance of hitting it big but REALLY it's more about just finding it. I'd have to have a lot to think about selling any. It's just too much work to part with the little bit I might find.

I do have some E-wastes that I could try to separate the gold from (and I will someday) but right now I know I don't have enough to be worth setting up and processing. In the meantime, I'll continue reading the books and the forum trying to learn the right ways to do it and maybe collect some more parts to scrap. If it was about making money, I think separating the gold plated parts and then selling them to other dreamers on E-bay is probably the way to go.

Anyway, I'll figure it out eventually unless it's just not possible.

bmgold2

 

[bmgold2]

O.K. I'll quit bothering everyone about my ore now. I got the purple color I was looking for. Without saying exactly what the problem was, I'll just say it wasn't the ore.

Thanks for humoring me as I worked at getting this figured out. I'm sure it still isn't a money making idea but at least I got what I was after.

bmgold2

 

[butcher]

The real test for ore is a fire assay, in a fire assay the high heat and chemical reactions help to release gold from the ore, this is something very hard to do with wet chemical methods as you are seeing from your results.
But even then not all ore will react the same, so the assayer will have to do some tests to see what may work with different ore and adjust his flux to be able to work with that ore,
Basically he has to change the chemistry of his flux to work chemically with the ores chemistry to be able to extract the valuable metals.

Many times the metals are extracted from the ore in a smelt, or assay, so that they can be tested for chemically.

That statement above "There's always a chance of hitting it big" that sounds like most miners and gamblers, and dreamers, yes there may be a chance, but in mining or gambling I always felt I had a better chance of getting struck by lightning, I do not gamble so I guess I have less of a chance of striking it big with only my mining, I guess I better be thinking twice about standing out in those lightning storms with my luck.

You really have not bothered anyone by this discussion, it is interesting, and it helps us all to learn, that is what we are here for.

I think you would have more fun fixing up a test kit to test metals, and working on learning that, I also feel you will gain more experience you can use practically, for both fun and profit.

With ore and its complications not every leach will work, even to test the ore, you are having to deal with the ores chemistry, and the state the gold or other metals are tied up in that ore.

With testing of metals you are also dealing with chemical reactions, but the metals are not locked up chemically in the jewelry or scrap. Although it will take study and practice it will not be as hard as trying to crack the combination of ore locked up chemically in some unknown rock.

 

[Geo]

the easiest way i can think of to remove excess nitric would be to dissolve gold until the nitric is depleted. why make a batch or try to use a batch that is too large for the amount you are working with. keep adding gold plate until it wont strip any more.

 

[moose7802]

the easiest way i can think of to remove excess nitric would be to dissolve gold until the nitric is depleted. why make a batch or try to use a batch that is too large for the amount you are working with. keep adding gold plate until it wont strip any more.

What about sulfamic?
Tyler

 

[butcher]

Actually I like using a combination of several methods to insure I do not have excess nitric acid when I go to test or precipitate gold.
Use minimum HNO3.
Use more gold to use up HNO3.
Use heat to drive off HNO3 as NOx gas.
Use Sulfamic acid.
I often use a little bit of all of these in a process.

Here he already has a high salt brine solution so evaporation may not be the best method to deNOx the solution, but Heat and added gold and or an keeping it acidic can help H2SO4, or sulfamic (which form some H2SO4) can help also to drive off HNO3 as NOx, the sulfamic itself will help to deNOx.

Basically he can use one method or a combination of several methods to DeNox the solution.





Lets look at another solution to dissolve gold. One that comes to mind since we are discussing a lot of dissolved salts in solution or a highly brine solution of gold chloride.

With HCl and bleach NaClO to dissolve gold we have a lot of water and salts in solution.
The bleach is mostly water (over 90% H2O) and is also basic and contains NaOH to keep the sodium hypochlorite in solution (when acidic it forms chlorine gas).

So when we use hydrochloric acid HCl (32% acid + 68% H2O) and bleach (sodium hypochlorite) (6% NaClO + 94% H2O), we see when we dissolve gold it is in a very dilute solution of water, the solution is a lot less acid than if we used aqua regia , because the bleach was basic, and the sodium hydroxide involved also neutralizes some of our HCl as we generated chlorine in solution.


The weaker solution works OK for thin gold foils or gold powders, but has a hard time attacking thicker pieces of gold, partly because of the more dilute and less acidic solution, where Aqua regia is highly acidic and can more vigorously attack the thicker gold.
we also have a much more volume of solution of with less gold in solution than we have when we dissolve our gold in aqua regia.

luckily we can easily drive off excess chlorine with heat.
But we really cannot concentrate this solution easily or evaporate the volume down easily, because when we drive off that excess water we end up concentrating the solution to salts of NaCl and tiny bits of NaCLO3 salts.

So with this solution if we have too much chlorine (oxidizer) in solution we can heat it to drive off chlorine, and add back water if we begin to cook out too much salts, or we could let it sit as long as needed in the hot sun (not an option here in the winter).

Here also a tiny bit of H2SO4 or sulfamic can help to precipitate lead from solution, and if you actually do wish to concentrate the solution somewhat, the H2SO4 here will help several ways, it helps when salts form from cooking them, helping to keep them more soluble, also when H2SO4 react with salts it forms HCl gas which dissolves back into the solution of excess water as we evaporate to form HCl acid in solution. it also helps to make the solution more acidic, which also helps to drive off chlorine and keep the gold in solution.
2NaCl + H2SO4 --> 2HCl + Na2SO4

 

[The Refiner49er]

Hello All-

I have not posted to the GRF for a long time, but wanted to add input on depletion of residual nitric. I believe using copper is very effective and in worst case some of the gold may end up cementing out if this process is taken too far. I see zinc is also commonly used as a precipitant with SSN and other leaches, it is certainly simple and may avert the use of alternative chems that may add to issues in waste streams.

I would like to ask if anyone has had success in reuse of SSN solutions rather than discarding, perhaps by dropping all possible metals, charging with additional salt and???

Thanks in advance for any comments!

 

[Lou]

Run it through an ion exchange resin.

Freechemist recommended several of the Dowex resins.

There are specific resins that are functionalized for specific metals.

 

[butcher]

Basically the SSN leach is a type of poor mans aqua regia, you are using salt and acid to make an HCl solution.
The H(+) here comes from the Nitric acid forming H3O in solution, the Chloride Cl(-) comes from the NaCl salt brine solution:
H(+) + Cl(-) --> HCl
The HCl in the salt water brine solution with HNO3 gives aqua regia type solution.

The active ingredients such as the gases needed to oxidize gold, and the active ingredients to put gold in solution are use up during leaching metals and other things in the solution are using up the oxidizers and acids, and before precipitating gold, we have to eliminate any free nitric acid, which basically leaves us with a slightly acidic salt water solution full of base metals, gold, or anything else in the ore that could be put into solution by the highly oxidizing chloride solution.

By the time you have leached and recovered gold, you do not have much in the solution that you would want to reuse again (salt is cheap) and what little acidic salt you had left from the acidic saltwater loaded with base metals, and whatever you used to precipitate gold sulfites, sulfates, or other chemical or metal precipitates just contaminate the acidic salt water further, with another chemical or metal.

Not much to reuse left, not worth the trouble to get salt out of the mix to reuse, clean salt is just too common and cheap (HCl itself is also cheap, not as cheap as salt). I can see no gain in reusing an slightly acid salt solution contaminated with metals and everything else, and if treated the salt water you could get from it still would not save you any money for the trouble, salt is just too plentiful and cheap.

Unless you can get nitric acid cheaper than HCl, I wonder why someone would anyone use the SSN leach. The nitric acid which is needed to make HCl in solution with the salt, price of nitric acid and HCl would need to be considered, if it cost HNO3 was High, or nitric was not easily available, or was more than the cost of HCl, then adding HCl to the leach could be cheaper than making it in solution using nitric acid and salt.