# Problem dropping gold



## Charles Connor (May 2, 2014)

Good afternoon, i`ve come up with this problem: i was recovering some gold from floor sweeps (did all the magnet and burning) and the SnCl2 test marks positive for gold, so (with AR) by the time i added the SMD, an orange foam forms and floats in the beaker, i`ve had this problem too with vacuum sweeps but the gold test was negative. So i wonder if some of you have also been in this situation and if could solve it. Thanks


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## FrugalRefiner (May 2, 2014)

An orange (or brown) foam sounds like you had too much nitric and didn't get it deNOxed. Did you premix your AR based on a ratio, or add nitric in increments? Did you use heat to drive the digestion to completion? After you dissolved everything, did you evaporate to deNOx or add a gold button or any sulfamic acid?

Dave


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## Charles Connor (May 2, 2014)

Here`s the thing, i used the same method as i do with the sweeps from a vaccum of jewerly polishing machines, i do not know the ammount of gold in it so i add the nitric until i see no reaction, i dont have a heating plate, also it was 1kilo of dust after burned. Also im like one of the few who uses urea to deNOx, it work every time for me, even the sweeps, its just this thime that the scrap came from the furnace and melting area... what i think is that it may have way too much contaminants and the ammount of gold could be like 2 grams per litre of solution, assuming thats the average from the color with the SnCl2


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## Pantherlikher (May 2, 2014)

Charles Connor said:


> Here`s the thing, i do not know the ammount of gold in it so i add the nitric until i see no reaction, i dont have a heating plate, also it was 1kilo of dust after burned. Also im like one of the few who uses urea to deNOx, it work every time for me, even the sweeps, ...what i think is that it may have way too much contaminants and the ammount of gold could be like 2 grams per litre of solution, assuming thats the average from the color with the SnCl2




So...what you are saying is you are special... unlike the rest of us in that Urea works for you... but does not in the real world.
You added nitric untill it stopped reacting, without heating. Why do you not need a heating plate but the rest of us do?
You also said based on the color of the test, you have like 2grams/ liter...
Show us where color indicates amounts? please, we could really use this information...

Ok...done insulting you and sorry for that but... 

Stop doing things half assed.... learn the whole procedure and follow it completely to insure you do not have problems and if so, you know why and how to fix it without adding to the vastness of the forum.

B.S.
...Again sorry for being harsh...


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## Charles Connor (May 2, 2014)

Dont worry gentelman, problem fixed, mjust let it settle for a couple hours... as i have not had any problems refining for a really long time i did not know what happened, in fact this was a new kind of scrap. im not that newbie in this field, im 18 and i already refine Au and Ag 8) and dont worry panther i know how we act when we know how things are done around here... Thanks for your time


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## FrugalRefiner (May 2, 2014)

The mix was probably different between the floor sweeps and vacuum sweeps, so your usual procedure was probably off a bit and you overshot the nitric a bit. If it's not too much over, the SMB will just deplete the small excess and the gold will drop. Be sure to test the remaining solution to be sure the reduction is complete. If there was too much excess nitric, you'll end up with some salts mixed with the gold.

Dave


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## g_axelsson (May 3, 2014)

Pantherlikher said:


> You also said based on the color of the test, you have like 2grams/ liter...
> Show us where color indicates amounts? please, we could really use this information...


Here it is...
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=18342#p184831

But I'm pretty sure Hoke mentions it in at least one of her books.

Göran


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## necromancer (May 3, 2014)

he fixed it, bet he will not post again until his next problem :!:


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## nickvc (May 3, 2014)

When doing sweeps you need heat and agitation to make sure all the values are exposed to the acids, if you haven't used nth I'd bet your material will still have values in them.


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## Pantherlikher (May 3, 2014)

I know Göran it is possible to scientifically get a close measure of how much gold is in solution. But based on the question and explanation of what has been done so far, how could it possibly be close to an accuate measurement?

I am assuming his results are based on color of past soutions. Not a measure of the solution in question.

Everything I have read so far about Urea.... leads me to believe that it will not "denox" very well. And adding nitric untill the reaction stops without heat tells me there would be too much free nitric for it to do anything. Except the addition of way to much urea which causes problems. Right? I am asking...

B.S.
...Trying to keep things straight in a foggy mind is very challenging...


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## g_axelsson (May 3, 2014)

This is a purely theoretically discussion on urea for denoxing a solution. I have no experience in urea for denoxing since I have never used it and doesn't plan to do it, so don't take my word on it, I wouldn't. This is just my mental picture of what is happening.

As far as I understand, adding urea to nitric acid should work, but not to nitric salts unless you have an acid present.

for example, if I dissolve copper and gold in poor mans AR (nitrate salt + HCl) I would end up with copper nitrate, copper chloride and gold chloride plus the original nitrate salt and HCl. If I would add urea to this I would turn the HCl and nitrate salts into gases and chloride salts, but the reaction would stop when I run out of HCl and people would mistake it for a complete denoxed solution.
What we have now is a micture of more or less of copper nitrate, copper chloride, gold chloride, nitrate and chloride salt from the nitrate we added and small amounts of urea but no HCl or other acid.
Adding SMB to this soup would turn gold chloride into sodium bisulfate and metallic gold.
Sodium bisulfate is acidic and with the chloride and nitrate ions in the solution it will turn the soup into aqua regia again and redissolve the gold.
Even if the left over urea can neutralize the nitric acid that is formed, when the gold powder is washed in HCl some will be redissolved when the dragged down nitric ions reacts with the HCl and forms poor mans AR again.

... and there is also the risk of forming explosive compounds with urea in certain situations.

Let me know if I my theory is just wrong or if there is some truth behind it. 

Personally I try to keep the nitric acid usage at a low level so mostly I don't need to denox or I can do it with one evaporation.

Göran


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## Charles Connor (May 3, 2014)

these are some formulas that come in the books i learned about the excess of nitric and deNOxing with SMB


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## butcher (May 3, 2014)

Urea with nitric acid will convert nitric acid to urea nitrate, a salt of the acid and urea.

Urea can decompose to form ammonia or ammonium compounds in certain reactions.

Both of these can cause problems, or even dangerous solutions with the reactions in recovery or refining of precious metals.

Impurities in a solution of gold chloride, gold dissolved in aqua regia,, like copper, even an almost pure gold chloride solution will have some degree of other metals involved, the amount of these other metals can be a small amount to heavily contaminated with base metals and very little gold, depending on what is in solution.

Urea will not destroy nitric acid.
Urea can destroy the NOx gases in a solution of nitric acid.
Urea can form salts of nitrates with nitric acid.

Metals like copper, or other base metals can form nitrate salts in solution.
Urea will not destroy nitrate salts in solution.

Urea can decompose the NOx gases in nitric acid, or a solution of gold chloride, but it will not destroy free nitric acid or nitrate salts.

If the solution was only gold chloride, with only gold in solution, and no other base metal (almost impossible most of the time), and there was not free nitric acid in solution, then urea would work to decompose the NOx gases.

But if there are other base metals involved, which is always the case and depending on the solution, that is just a matter of how much.

And if there is free nitric acid in solution, depending on solution and how you performed the work, another question of how much.

The Urea may or may not work to De-NOx the solution, it may or may not form ammonium compounds, which could interfere with the PGM metals if they are in solution forming compounds making recovery difficult of the PGM's later, or form urea nitrate or ammonium compounds that can possibly make a dangerous situation in recovery refining or waste treatment...

Much depends on the solution, the free nitric acid involved, the base metals involved and other conditions of the reaction.

Metals in solution can form nitrates, like copper nitrate, with acid like HCl these nitrate salts can again form (a form of) aqua regia which will re-dissolve the gold in solution, even urea nitrate and HCl will dissolve gold.

Basically, I a have a hard time explaining this, and the complications involved in the use of urea in a solution of aqua regia, except to say if conditions of the solution are right it will work, but most of the time you will have too much nitric or base metals that will cause problems, or platinum group metals where urea will cause problems with recovery, and you or are taking a chance of creating an explosive compound when using urea.

Urea is not needed in recovery or refining.

If you need a chemical to de-NOx use sulfamic acid, (which can be found as a grout cleaner to clean grout from ceramic tile, at stores like Home depot), using sulfamic acid which actually has benefits, like making H2SO4 in solution that can help if you are going to evaporate the solution, or to help remove lead from the solution as lead sulfate.

Learn how much nitric to use, and add only the amount needed.

Use Heat to evaporate the solution, to decompose NOx gases and free nitric acid.

Use heat and more gold to de-NOx the solution, consuming the free nitric acid in solution.

Use urea you have as fertilizer, and learn to recover and refine without it, it will be safer, easier and you will have less problems.


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## joubjonn (May 3, 2014)

I usually denox with sulfamic. Sometimes I'll use the gold button to eat up very small amounts of extra nitric. Trick is to use as little as possible. Forget about the ratio 1:3 HCl/Nitric. That's not the way we do it here. Sometimes it is difficult to know the exact amount for processes like ceramic cpu's. In that case I won't use a gold button, just a few pinches of sulfamic. And yes SMB is good for denoxing a very small amount of excess nitric.


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## Charles Connor (May 3, 2014)

Absolutly i agree with you Butcher, i want to do it as pure as possible the fact is that where i work, they left me a 50 kilo sack of urea and here in costa rica getting chemicals is a matter of a lot of permissions and buying laboratory equipment is really expensive, for example: because of the taxes a heating plate that is $900 in Corning USA, here they sell it for like $1600, so, its like working with what you get, i can get the HNO3, the HCl and the SMB, wich is what i mainly need. In fact where i sell the gold they have it tested every time and it does not goes under .9995, so i wonder if making it without urea would get me those .99999


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## butcher (May 3, 2014)

The heating plate can be made from 0r of many different things (if you have a way to cook food) you can get or make a heating plate to give heat to a solution, control of the heat is needed.

Personally I would use the urea for fertilizer.
Even if you cannot get sulfamic acid, you can still work with out it.
There are several methods to choose from, you can also use combinations of these, to get the desired results.

Learn to use acids wisely.
Use heat.
Use gold.


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## g_axelsson (May 3, 2014)

I see, the urea doesn't touch nitric acid or nitrates unless there is quite a lot of HCl in the solution.

According to http://en.wikipedia.org/wiki/Aqua_regia#Decomposition_of_aqua_regia
In a first step aqua regia decomposes into nitrosyl chloride and chlorine, then in step 2 the nitrosyl chloride breaks down to nitric oxide and chlorine.
The second step is in equilibrium with nitric oxide and chlorine dissolved in the solution. Urea attacks this equilibrium by removing the nitric oxide and then step 2 transforms more nitrosyl chloride into nitric oxide until the nitrosyl chloride is gone.
This will also consume HCl which is turned into Cl2(g).

This brings some light to the process of denoxing with evaporation and HCl additions.

When evaporating both HCl and HNO3 goes off as gases, but when we add HCl to the concentrated hot solution it reacts with the nitric acid, turning it into nitrosyl chloride and then into gases. Since we have heated the solution the resulting gases is quickly expelled and the breakdown of the nitric acid continues.

Basically the heated evaporation - dilution with HCl and urea works based on the same principle, drive the breakdown of aqua regia to the gas state and expel the gases from the solution.

Am I getting close?

Göran


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## butcher (May 3, 2014)

Very close, indeed almost spot on.

Actually much of these reactions are over simplified to try to understand what is going on.

In these reaction with metals and the acids many things are going on at once, these equations can help us to understand some of it, but it would be very hard to write an equation or describe all of the reactions happening, and each batch of gold and aqua regia and base metal can be somewhat different, base metals in solution can add to the complexity, base metal can also react with these acids and gases formed in solution, forming base metal chloride salts and base metal nitrate salts, on evaporation we can have nitrate salts, adding a little free HCl to the concentrated solution can again form aqua regia, by reaction of the nitrate salts and HCl, giving us another red cloud of NOx gas as these nitrates decompose, the second evaporation, can help to decompose more of the nitric and NOx gases in solution, and a third evaporation is recommended to completely remove the last possible trace of the free nitric acid.

We have several approaches for this problem. 
Evaporation to syrup three times with a small addition of HCl to the concentrated solution between the process.
Leaving undissolved gold, or adding some gold to consume the nitric.
Sulfamic acid to destroy the nitric acid.
Heat can be a very important tool, that should not be overlooked.

We can use one or a combination of these methods to overcome the problem of nitric or nitrates in solution.

I like to use one or many times a combination of these methods, and depending on what I am working on I may use a bit slightly different approach on different batches, first limiting excess HNO3 where you can, I try to calculate how much that may be needed (when I can), measure it out and add it in small increments with heat, giving time for the reaction to complete before adding more nitric acid, and sometimes even leaving a bit of undissolved gold which I will get on the next batch, I can use sulfamic acid to help rid nitric, which also has the benefits mentioned above, then there is adding the button of gold and heat to consume free nitric, and the evaporation process, I like to use combinations of these methods, sometime one or more during the process,I had so much trouble with nitric acid, that I want to be sure I do not have that problem again, and since getting a better understanding, and using combination of these methods to eliminate free nitric from solution, I have not had the problem since.

Free HCl does not cause any problems as long as the nitrates or nitric or NOx gases are not involved to re-dissolve the gold, or to prevent the gold from forming a precipitate.

Not using heat in recovery and refining, to me would be like eating all of your meat raw (it is better cooked), Heat in recovery and refining has many benefits, also well as cold or cooling can have benefits with many things we do, these both can be very important tools to many reactions.


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## g_axelsson (May 4, 2014)

Thanks Butcher, you have raised my understanding of the denoxing process another step. 8) 

Göran


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## Pantherlikher (May 4, 2014)

Thanks to ya'll for a better understanding...

Now to apply everything to costa rica and it's problems getting stuff needed. This can pose a problem which can be solved with alittle research.

Who's sending me plane tickets to costa rica so I can do the on the ground research? Just kidding...

Ok, a heat source. Are you allowed to goto the dump/trash storage area? Do you have coffee there? A coffee maker is great for a heat sorce.

As far as adding nitric acid, do not use the 3:1 ratio. Explained her numerous times as it is too much nitric for the batches we do. I would think it safe to add half of the calculated. Let the reaction stop and then add some heat. Not to boil but to heat. At this point, I would look to determin if all the metals are close to being dissolved. If not, add alittle more and wait with heat. When there is very little but some metal still undissolved, I would stop and process the liquid from here saving what is left for the next reaction. This would eliminate any excess nitric to worry about.

Let us know what you think. And good luck.

B.S.


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## Charles Connor (May 4, 2014)

I have already seen the coffee maker being used as a heat source and some people use to put some sand on the plate, will give it a try, because once I used an electric stove with an aluminum piece so the heat weren't that direct and my 2L beaker broke, so I don't want that to happen. 
Göran and Butcher that's a new level on de-NOx-ing gentleman!


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## AtoMIKu235 (May 19, 2014)

After boiling and using Urea and then trying to drop with SMB, precipitate dissolved, , , Doooooooh I think i have Problems with to much SMB and need a little more De-NOX , , , Managed to drop gold by adding very small amounts of sodium Hydroxide, gold likes to drop first, but if you add to much the other metals will follow , , , , test with SnCl untill no gold, preciptate is unusually fine, it will settle in 3 hours, check for tiny metalic gold particles on the surface, spray them down , , ,Mix powder with HCL to remove base metal contaminants , , , have a small problem of NaOH reducing AuCL to metalic gold which forms on side of beaker , , , , , I think this is a good new method to recover failed refining , , , have anyone got any idea,s on this subject , , ,

Micky B


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## butcher (May 19, 2014)

My idea is not to use the hydroxide to lower the pH, gold will precipitate just fine from acidic solutions.
Why add something that will contaminate the gold you are trying to refine?
Our purpose is to leave base metals behind not drag them along with the gold.

Spending a little time reading the forum and you will find a lot of information on this topic.


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## AtoMIKu235 (May 19, 2014)

The fact is my NaOH method works, there is no contaminants as far as i can see, and after using Borax and sodium carbonate flux my gold is relativly pure, and tests ok with NHO3 , , , Better than throwing it in the waste tank

Mickey B


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## butcher (May 19, 2014)

Mickey,
No offense but I do not believe your methods are working (or at least as well as you believe them to be working).
yes you may be able to recover some of your gold, but my guess is you are losing gold and making it more difficult than it has to be, I believe from reading your posts (Boiling, use of urea, NaOH, and using NHO3 for nitric acid...) you can benefit from more study to learn better methods of recovery and refining these precious metals.

If you do not see where things are broken it would be hard to fix them.


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## joubjonn (May 19, 2014)

Sulfamic, buy some. It works every time. Or just don't use too much nitric in the first place which was not my method In the beginning but now that I'm getting better at this and seeing an actual "pipe" when my buttons cool I know I'm doing it right. Which would not be possible without the wisdoms of this forum, from folks like Butcher!


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## Anonymous (May 19, 2014)

Mickey what do you define as "relatively pure?" Can you give me and idea of where you mean with regards to this purity? 

Jon


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## Anonymous (May 19, 2014)

joubjonn said:


> Sulfamic, buy some. It works every time. Or just don't use too much nitric in the first place which was not my method In the beginning but now that I'm getting better at this and seeing an actual "pipe" when my buttons cool I know I'm doing it right. Which would not be possible without the wisdoms of this forum, from folks like Butcher!



If you clean your gold properly mate you'll always get a pipe regardless of the accuracy of your drop.


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## Chirou (Oct 14, 2018)

Hi guys i heard that's if i run out of other chemicsls i can denox with smb. But how to calculate IT than? Add untill no morę fizzing or what? Smb od really chrap here and well i got urea but i decided i dont want to use IT after reading this toppic. And i'm on middle of process. Into one batch i already added urea  And its shame to admit but due to some spends i cant afford sulfamic acid this Monty  Its not that's expencive but the cost is half what i got left lets sat Igor 42 euro to end of month and it will cost 25 plus delivery ... But currency here od different xd. And Igor to struggle roll end of month im doing all recovery outside and its getting colder. Please advice me and help guys^^


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## butcher (Oct 14, 2018)

I would add a gold button and heat solution.


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## FrugalRefiner (Oct 14, 2018)

As butcher said, you can add more gold to use the excess nitric.

Or you can heat your solution gently and evaporate it down till it's like syrup, then add a bit of HCl. You may need to do it a few times.

Or you can add a bar of clean copper to the solution to use the excess nitric and cement the gold out of solution.

When you add too much urea or SMB, it starts to create other problems. In the future, the best procedure is to add as much HCl as you expect to need, then add the nitric in small amounts at a time so you use just enough to dissolve the gold. Then you don't have to deNOx.

Dave


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## Chirou (Oct 14, 2018)

Don't have any gold yet. These are my first batches. Into one i added urea and well i think it's bad cause all truned brownish-black and i noticed some clear/white crystals and as far i read this is also urea's doing and in second one it looks like theres a little bit of gold residue but the color of solution is still greenish brown. And i'm not sure if i messed up here adding urea earlier or in some other way 
first batch are PCBS in big bucket and it's rather hard to heat it now it is around 6liters af solution in total. (processed like 3 full PCBS[clear without any components or tin, maybe on one or two a little bit of tin] buckets in it). And well now i'm broke at this moment and a bit confused. I'm searching for some cheap sulfamic acid but well its still almost 3/4 of what i got till the next paycheck. 
And i would like to procees these gold solutions as soon as possible cause cold weather is coming. And i;m doing everything outside 8km from home with no electricity there.


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## butcher (Oct 14, 2018)

Chirou,
I would like to hear more details of how the gold was put into solution, more about the source materials, the more details you explain will give a better picture of what you are dealing with.

Were there metals left undissolved, or were whole circuit boards involved...

Take FrugalRefiner's third advice and add a clean bar of copper to cement values from the acidic solution. from your short description of your solution, you have base metals in solution, any gold will convert to metal.


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## Chirou (Oct 14, 2018)

Well first batch is from gold plated pins i put them into nitric acid, let them sit in 3 jars (i got a lot of pins).
2 of 3 went great o got all copper disolved and was left with only gold foils(of course with some little leftover copper). Third one went bad there was some iron containing pins i didn't notticed and i got Fe2O3 inside with foils. I dissolved all collected foils and one batch with a little bit of Fe2O3 in AR. And got pretty umm dark yellow solution a littlebit green i can say. I used urea well my bad. And added SMB. It looks liek gold has precipitated cause i saw brown residue on bottom, but still solution remained almost the same color, got lik greenish brown now and it sits 2nd day. I didn't had enought time to filter it today. 

Second batch is clear PCBS in plastic bucket i put them whole inside (i got a lot of goldplated pcbs and connectors etc from place where i work for free). I put whole bucket and added a bit of water than 35% HCl and 65% HNO3 and i think i added too much cause i was able to process almost 3 buckets of pcbs in this batch. Everything was going great beauty green colour. And well i added urea untill no more fizzing, waited some time. And than added SMB diluted in water pretty much nothing happened i waited some time and added one little spoon of powdered SMB thinking (if i drop some copper i will rinse it multiple times with water and than rinse with HNO3 to get ridof copper). Solution turned brown so i left it be thinking that its going well but when i checked it after around i'm not sure 1 hour i saw it became more black than brown, and after moving a bucket a little i noticed a little crystals stuck to side of bucket clear maybe a little white (hard to say cause bucket is white). I did some research on out forum and found that i messed up by using urea.... and that these crystals are probably urea nitrate (i hope not) or Copper Chloride. (both are soluble in water) but now i'm not sure if my gold powder stayed in solution or is trapped under the cristals. I got one of my very first batches like test batch and there i got the same cristals in jar with black-brown powder trapped under but here i can't see it. And i got confused and i don't want to lose any gold. I got a little copper slab from radiator maybe it will be od use. But still please advice me on how to not mess up anything more ^^ i'm not expecting huge ammounts of gold but still it's waste to pour it out. 

Now i know not to use urea.... I need to buy sulphamic acid but well i probably need to wait till next month. Or find a way to earn something on side. I'm neewbie lets call me refiner. And i just want to make little gold ingot from all that i can get where i work during my life and later pass it to my children (when i get some XD ).

Thank yoy for your time ^^.


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## Chirou (Oct 14, 2018)

Oh sorry i forgot to mention that in PCB's batch when all metals were dissolver i removed pcb's and filtered solution from leftover little pieces of pcb's etc. Than placed it in cleat bucket and started with urea and SMB.

Update.
As i think about it now i can heat up solution but in portions. I mean i can't heat whole bucket now but i can take my old grill fill it with with sand i will get from near lets call it excavation. place it under a little fire and put small jar onto it it should work like crock pot (i think i wrote it wrong) like one Cody from Cody's lab uses.

Of course i'm no specialist. I kinda want to stay and try gold recovery and never give up cause this all gold recovery idea, forum, movies on yt etc got me out of depression and gave me a little goal little something what i can do. ^^ ill strach picture od Cooper slab i got but i Think i will use something a little smaller easier hang inside.


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## butcher (Oct 16, 2018)

As long as you have saved everything you still have your gold, adding the copper will cement any valuable metals from solution, the Oxidation of the copper metal atoms will give up their electrons to any gold ions in solution, as the gold ions gain electrons (reduction) they become metal atoms which join to become a powder heavy enough to precipitate from solution.

The cemented gold will be black (still impure gold), which may be mixed with other insoluble salts.
The solution should be acidic (yours probably has quite a bit of free acid), stirring will help, as each gold ion in solution must come into contact with the pure copper atom for the electrons transfer, some gold may stick to the copper which can be brushed off with a toothbrush if needed.

Store your gold after decanting, we can discuss washing and further steps in more detail later, for now, study up on proper and safe disposal of the toxic waste you have created thus far, ask any questions you do not understand after reading more on the process.

If you are truly ready to learn to recover valuable metals and learn to refine them you have found the place.

I suggest forgetting what you think you know about it, and let us get you back on the right track of learning how to...


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## Chirou (Oct 16, 2018)

Ok thank you very much. 
Problem with waste is noone here really takes care of it but as far as i read if i cement out copper with iron and than make the solution basic i can bassicaly pour it down a toilet. I Have to cement out copper cause it's toxic in solution. Of course correct me if i'm wrong cause it's very possible.

I'm working 14-22 now so i don't have time to go and check on my gold  but i got few nice pieces of copper from work and i can use it i think i will even get more tomorrow. I'll get friday off and go to donate blood, and than go to place where my gold solutions are and start cementing it out. I got really a lot of gold containing scraps PCBS etc from work so gold recovery its a great way for me to kill free timem have fun and create some small button or maybe some ingot over years. 

Thank you very much for your help. I will post any progress in this toppic ^^.

If my solution would be not acidic enought i understand i will need to add some acid. And as i deduct from copper solution should turn more blue when gold will be cemented. XD


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## butcher (Oct 16, 2018)

After cementing out the copper with iron, Iron will not replace all metals from solution.
https://en.wikipedia.org/wiki/Reactivity_series

we need to bring the pH up above a neutral solution, into the basic side, as you can see from the chart below not all metals will precipitate, or have a lower solubility at the same pH, some metals as you can see from the chart are amphoteric, and can be soluble in acidic condition, then lower in solubility as you raise the pH, and as the solution gets further basic will dissolve back into solution, some of the major amphoteric metals like chromium, zinc, and lead you can see from the charts graph below.





As I said earlier forget what you think you know and study the material available to truly gain an understanding, I would not dump anything down a toilet, hopefully, the men living upriver from you are not dumping their waste down their toilets, what people flush up the river, is the water down river people drink from.

Study this:
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=47&t=1300
There is much more in our safety section.
Understanding how to deal with waste has many of the principle basics needed to understand recovery and refining of precious metals, without these principles you would not only struggle in your understanding but will put yourself and everyone around you in danger.


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## Chirou (Oct 18, 2018)

Ok i've been to place where i keep all my gold etc. I put some copper pieces (i think i can call it rods) into solution Well i didn't noticed to much of change after 4h only that cooper got lighter so i guess that it started to get into solution. I stirred it few times. Saturday i will go and check on it and continue process. And i filtered one jar got a little bit of gold dust on the bottom. But solution remained green so i put copper into it as well. 

I'll report Saturday or Sunday. And now i'm starting to study how to deal with wastes as you said ^^. 
Thank you very much.


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## butcher (Oct 18, 2018)

The copper is being oxidized giving up its electrons, the copper atoms will go into solution as ions (atoms missing electrons), as copper atom gives up its electrons to the acid the acid is reduced (gain of electrons), copper ions color the solution, the ions metals which are less reactive than copper in the electromotive series of metals will gain electrons from the copper atoms (the copper being oxidized, will reduce these precious metal ions to precious metal atoms with a full shell of electrons, leaving copper and the metals above copper (see the electromotive series) in solutions as ions, or ionic salts of the metals (cations), and the ionic salt of the acids used (anions), leaving you with your values, a toxic solution of many of the very dangerous heavy metals in solution.

Note, Tin in solution complicates matters, the tin will form gold colloids, these colloids are already reduced to metals in solution, so copper cannot reduce them as they already have all of their electrons in the metals atom, we cannot test for them with stannous chloride or ferrous sulfate as neither reducing agent can reduce the already reduced gold, we cannot precipitate them from solution as they gain charges that repel each other the clusters of reduced gold cannot gain a large enough size or mass of gold atoms in the cluster to be seen or to overcome gravity in this solution of repelling clusters of gold colloids.
It is difficult to break the colloidal bonds to recover this gold, which can be a good way to lose your gold and not even know it.
Tin should not be dissolved with tin or solder from circuit boards.


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## Shark (Oct 18, 2018)

Butcher,

You can make some of the science behind refining sound like grade school home work. Thanks for your easy to read and understand explanations. I have learned a lot just by reading your posts, even when they didn't pertain to my situation at the time, so many became helpful later on.


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## Chirou (Oct 18, 2018)

Yea, your explanations help a lot they remind me of school times XD. I'll check everything again in weekend and report everything.


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## Chirou (Oct 22, 2018)

It's me again ^^. From conector batch i got nie brownosh black gold powder. But from PCBS batch i got some crystals (like on attached photo) i did some research on our forum and i found that it is most probably urea nitrate and it dissolves in water. I read that gold powter is trapped under it. But maybe i'm wrong and you guys got some ideas ?


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## butcher (Oct 22, 2018)

Test the solution for values with ferrous sulfate crystal in spot plate for gold, or with stannous or with both.

I am assuming you used copper to replace values from the solution.

You can have several different salts and metals, some will be soluble in cold water. 
Lead is much more soluble in hot water than it is in cold.
HCl will dissolve salts like copper I chloride.

Leaving you with your recovered values that will need refining.

And your waste solution's of toxic metals to deal with.

Whole Printed circuit boards the tin involved can lock up your gold in solution, one good way to lose your gold.


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## Chirou (Oct 24, 2018)

I'm using only clear circut boards from work ^^ so colled scrap XD this and i don't take that containing tin ^^. Well i noticed this crystals before using copper to precipitate gold and my guess after reading a bit on out forum is that it's one of ureas unwanted side efects most probably urea nitrate but copper salt is possible too. I will just rinse it multiple times with hot water if it will still be there i will use HCL (i run low on it unfortunately). And today i got my sulfamic acid after selling some computer parts so won't use urea anymore ^^ a little progress .

But thanks to your help i'm starting to wonder how can we break down colloidal gold+tin if something like that happens to us.


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## butcher (Oct 24, 2018)

While with electrolysis or boiling in acid, it is possible to break the colloidal bond, evaporation, and incineration is the best method.

You cannot test for gold when the gold is in a colloidal state, you cannot precipitate it from solution...



The forum Search found 762 matches for the words colloidal gold:

http://goldrefiningforum.com/phpBB3/search.php?keywords=colloidal+gold


Try using other keywords in your search for more results on your quest to learn how to deal with colloidal gold.


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## Chirou (Oct 28, 2018)

Ok well rincing wbite crystals with Water a d HCl did nothing  it only got more clear i decided to make a little bit of ar and let it sit while mixing it. This should get the little bit od Gold dust from three into solution. And i will precipitate it again but white crystals hadn't dissolved even in ar i don't understand what they are. The rest i got ready for smelting and the batch dropped down with Cooper is waiting to purify it, well it takes time cause i couldn't find another dish as big as bucket and i didn't wanted to drop it inot these crystals so i separated it into few pots.




update guys my little success ^^ its only from connectors batch maybe it's not the best and cleanest but at least its mine first ^^ i got few little beads after smelting i hoped to get one buton but well it is here


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## Shark (Oct 30, 2018)

I don't think everyone makes a three nines button the first time, and it isn't really expected first time around. It will be easier the next time. Study up on various ways to filter your solutions as well. Good filtering can make a button much better over poor filtering. 

Here is link to my first button and how it looked after I refined it a second time. Read my last comment and pay attention to how long it took me.

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=20981


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## Chirou (Nov 4, 2018)

Guys what is the best way to clear pcbs or pins from tin solder ? I heard HCl but oneguy on forum explained me that then gold that was eaten away by tin ends as colloid anyway. Eventually it can drop down as fne powder but it will be that small amount that we can't even see it. Any better ideas ? Or some wisdom? I will surely get a bit of scrap with tin and i'd like to proccess it corretly


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