# What does cemented gold look like?



## cejohnsonsr (Mar 14, 2013)

I've only seen 1 example of cementing in a video by lazersteve. He cemented silver with copper. I put a copper split bolt in some HCl/Cl that I had already dropped with SMB, but that I didn't think yielded enough. The bolt turned black after a few minutes. It shed a lot of black flakes after a few hours. I brushed it until it was pretty much looking like copper again & put it back in the solution. It began to turn black again right away. Is that black flaky stuff the gold I was missing after the 1st drop?

Thanks

Ed


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## butcher (Mar 14, 2013)

cejohnsonsr,

What ever it is it is lower in the reactivity series of metals than copper, otherwise it would have not have cemented out of solution onto copper, below copper in the reactivity series of metals is:
silver, palladium, mercury, platinum, and gold.

We can rule out mercury and and silver as these are not soluble as chlorides, so this leaves us with possibility's of palladium, platinum, and gold.

So my guess here it is gold that was still left in solution.

Now Google these and study them, (reactivity series of metals), and (the solubility tables), studying these they will be very helpful to you in the future.


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## goldinsulator (Mar 14, 2013)

SO would it be better to drop gold from hcl/cl using copper then smb ,
"IF" pins fingers or other items that contain copper and other metals and the color of the solution is green instead of a pretty yellow?????
I also have a green hcl/cl solution, just been waiting for s.c. for testing and my crucible to arrive.

before I process..

John


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## cejohnsonsr (Mar 14, 2013)

Thank you again, butcher, for an answer I can understand. I thought it should be gold since the material was foils from unpopulated boards. I had just never actually seen any metal being "cemented" except for silver in one of lazersteve's videos. I didn't think I had gotten all the gold I should have. I have another container of "spent" AuCl to try when this one finishes. Glad I haven't thrown anything away. I've seen a couple of tables showing the reactivity series, but I'll study the one you suggested as well as solubility.

I'm also wondering the same thing as John. Why didn't all the gold drop with SMB? 

John, you can make your own stannous chloride way cheaper than buying it. On lazersteve's site you can buy tin powder for $1/gr which you mix with HCl 1gr/30ml. Heat it up a little while it's reacting (until all the tin dissolves). I keep mine in a bottle with a stopper/dropper. Steve says you need to freshen it up a bit every now & then by adding a little more tin to the solution. 

Thanks again, butcher.

Ed


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## butcher (Mar 14, 2013)

I use lead free solder to make stannous chloride, it can be bought where you buy solder look for 95% tin 5% antimony, hammer it flat as possible, cut it into small pieces, I dissolve it in HCl with heat, I leave a small piece of tin in solution and store in a small amber bottle, it keeps a little longer if slightly acidic and with some elemental tin, Laser Steve has made some very detailed instruction on how to make it.

Several reasons you may not get all of the gold to precipitate from you solutions, oxidizers such as nitric or chlorine re-dissolving gold, or keeping gold from forming, dirty solutions holding gold in solutions, oils even from your finger prints, or organic materials, or other base metals like high copper solutions, metals in solution if in high content the gold can kind of join to or plate to the other metals and will not precipitate as easily, and tin which can actually reduce the gold to metal, but it cannot be tested for with stannous chloride as it is already reduced to metal colloids, these gold colloids repel each other in solution keeping themselves suspended (these will also not cement out of solution onto copper because they are already reduced (tin in solution with your gold will steal your gold from you).
Here is were pretreatment to remove the oils and carbonaceous materials with incineration, mechanical or chemical treatment to remove tin, mechanical and chemical treatment to remove base metals from our gold is needed, and removal of oxidizer before we try and precipitate our gold gives us much better results, the pretreatment are actually some of the most important steps to recovery of gold, but can also be the most easily overlooked or skipped in the process.


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## cejohnsonsr (Mar 15, 2013)

Thanks again, butcher. I think I'm going to make a fresh batch of stannous today. This one might be getting old/weak. 

I don't think the material I've processed so far should have any tin in it. It was just fingers & unpopulated boards. I looked last night & was surprised at how much more had dropped (cemented) from my "spent" solution. I'll be working with that for a while this afternoon & then trying to straighten out a batch of CPUs that didn't go right either. I'm just thankful that there are people here who are willing to help me learn. I read & search a lot, but it always comes down to "hands on" & a little help from someone with experience. 

Thanks again,

Ed


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## Marcel (Mar 15, 2013)

Gold cements as a milkchocolate brown layer on copper. Palladium dark grey, almost black.
It´s a poor man´s PM tester btw.
But be careful, you could have both in solution. First the gold will show up with its color, then when it all has been precipitated the color will change to dark grey for palladium.
I have never seen platinum or those other PMs of the PMG cement, so therefore you gotta ask Steve, or somone else who is familiar with these metals.
I have two bottles filled with AUCl and PdCl, so I can always test things or check how the reaction should be like with known substances.


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## FrugalRefiner (Mar 15, 2013)

cejohnsonsr said:


> Thanks again, butcher. I think I'm going to make a fresh batch of stannous today. This one might be getting old/weak.


Ed,

This is why you should have some standard gold solution on hand. If you feel your stannous chloride might not be effective any more, you can test it on a drop of standard gold solution that you know contains gold in solution. That way you know if your stannous is still active instead of having to guess.

Dave


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## cejohnsonsr (Mar 15, 2013)

Thanks, Dave. Yeah I have slowly been coming to that conclusion. So far I haven't recovered enough gold to be able to have a known gold bearing solution on hand, but I think what dust I've recovered so far, combined with what I'm about to recover, should allow me to set a little aside just for that purpose. I was thinking I'd take some foils & clean them very well, then dissolve in HCl/Cl, then drive off any excess Cl with heat & keep a few ml for stannous testing. To be extra sure of my test solution, I'll make a fresh batch of stannous.

Ed


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## FrugalRefiner (Mar 15, 2013)

cejohnsonsr said:


> I was thinking I'd take some foils & clean them very well, then dissolve in HCl/Cl, then drive off any excess Cl with heat & keep a few ml for stannous testing.


That is exactly how I made my first gold solution to check my stannous. For a first solution, used just to verify the activity of your stannous, the _amount_ of gold isn't important. It is sufficient just to know that gold is in solution. A few foils in a couple of milliliters of solution is all you need.

Once you have a little more gold to work with, you can make up an more "standard" solution with a weighed amount of gold in a measured volume of solution, e.g., 1 gram of gold per liter. 

Dave


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## kkmonte (Mar 15, 2013)

Another question for cementing out metals. My question is do you need to saturate the acid with the higher reactive metal in order to drop out the lower (or is it lower metal to drop out the higher?) ?

For instance, If you had an acid solution capable of dissolving 100 grams of copper. Say you had 75 grams of copper dissolved and 5 grams of gold dissolved in this solution. If you throw in the copper bus bar, Will the 21st gram of copper dissolved start knocking out the gold? (the 95th through 100th gram of dissolved copper) ? Or will the first 5 grams of copper cement out the gold?

Thanks
Ken


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## butcher (Mar 15, 2013)

kkmonte,

Acids and oxidizers will take electrons from the atoms of metals, when the metals lose their electrons we call it oxidation (lose of electron), the acid or oxidizer (we will use chlorine and HCl for example) are already is missing electrons (so it is called the oxidizer) the chlorine is reduced (gains an electron, the one it stole from the metal), the metal (lets use gold and copper here) gold joins with three chlorides and forms gold chloride AuCl3 (this is a salt of gold), (acid + metal = salt of acid and metal), the copper can join with two chlorides and make a dissolved copper salt we call copper II chloride CuCl2, both of these salts are dissolved in solution.

Now say we want to use copper to get our gold back out of solution.
first if we do not have free acid (which can dissolve more copper into solution, the copper would not dissolve into solution, because all of the acid was reduced and is no longer an acid but a salt in solution, but in reality we may have a little free acid to consume a tiny bit of copper but we will overlook that here.

What we are doing is a replacement chemical reaction, we will replace the gold in solution with copper, this is electrochemically going to move electrons, the copper has all of its electrons, the gold is missing electrons (but now shares them with 3 chlorides), the copper is more reactive than gold, it is higher on the reactivity series of metals than gold, meaning it will give away its electrons easier than gold, or it can reduce (gain of electrons) gold back to an elemental metal (having all of its electrons in its atoms), so when we put a clean bar of copper in solution the gold chloride salt comes in contact (this is also a contact reaction) with the copper, the copper gives electrons to the gold (copper is oxidized loss of electron) and (the gold is reduced gain of electron), the other copper in solution as a dissolved salt (when we first use the acid) would not do anything but remains CuCL2, also note the gold had 3 chlorides, the copper only joins with two, this mean we will end up with a few free chloride to take another copper that it gave us gold, and in the end we only dissolved the amount of copper from our buss bar that we had gold and the little free acid, after that no more copper would go into solution, the gold being reduced (has all of its electrons back) so now it is a metal of gold, only it is a brown powder, well here it will probably be an impure gold (some copper contamination) making it black powered gold metal...

I do not know if I explained this to make it understandabel.


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## kkmonte (Mar 15, 2013)

Hi Butcher, thanks for explanation, I think I understand. So the answer to my question is it will only consume the amount of copper required to give the gold back its electrons.

On a side note, why do they call it reduced when it actually gains something?  To me when something is reduced, it loses something.

So I think in a crazy way I understand what you typed. Now from reading the forums and processing fingers, etc. I know you call it Copper II Chloride (the green solution that people use to dissolve copper off of gold fingers). I'm guessing this is because copper joins with two chlorides. So you add the oxidizer to steal electrons from the metals to form salts. H202 is the normal oxidizer for making copper II chloride. So when dropping copper into copper II chloride, the thing that will determine how much copper gets dissolved is the amount of "holes" that are available in the oxidizer. More Oxidizer equals more room to steal electrons from copper. Which is why you need to add more H2O2 or bubbler. 

So a bubbler isn't actually getting rid of electrons in the solution, it's adding more Oxygen (this is the oxidizer in that case) that can steal more electrons from the copper.

Another question then, if people call it Copper 2 Chloride (because when you run out of oxidizers, you are left with Copper I Chloride, correct?), then shouldn't people call it Auric 3 Chloride? I've only heard people call it Auric Chloride ? And then in that case, once you heat the solution to drive off excess Chlorine, are you left with Auric 2 Chloride?


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## butcher (Mar 16, 2013)

I did not name this stuff, if I did you surely would not like the names I chose either :lol: 

I will try to answer some of the questions.

Hi Butcher, Thanks for explanation, I think I understand. So the answer to my question is it will only consume the amount of copper required to give the gold back its electrons.

*Correct you got it.

On a side note, why do they call it reduced when it actually gains something? To me when something is reduced, it loses something.

*These terms are used more in explaining how an electro-chemical reaction works, like in batteries or your silver cell, where you are either generating current through a chemical reaction, or are using current to force an electrochemical reaction, but the principle applies to a lot of the types of chemical reactions we do with metals and acids, and in the reaction of cementing one metal with another metal. 

*In the cell we use current from an external power source (a battery or direct current power supply, some call a rectifier) to drive the electro-chemical reaction, the anode (+), (we will use impure silver here for our anode) (Because our power supply removes electrons from the anode), the silver anode dissolves, (or is oxidized) into solution (in the nitrate solution becoming silver nitrate, AgNO3), (you see here one silver CATION Ag+ joins with three free nitrate ANION’s NO3- to form AgNO3 salt dissolved in solution), then on the other side of our silver cell we have the cathode (-), this negative electrode (lets use a pure silver cathode here), this pure silver cathode is surrounded by the silver nitrate solution, (our power supply has supplied the cathode with excess electrons), So here when the silver nitrate is in contact with the cathode the cathode supplies the silver with the electron (that was taken at the anode), so the silver is REDUCED back to metal, freeing the three nitrate Anions (which can migrate over to anode to get another silver losing its electron there), the reduced silver plates out onto the pure silver cathode or builds a silver crystal of metal having all of its electrons back.

So I think in a crazy way I understand what you typed. Now from reading the forums and processing fingers, etc. I know you call it Copper II Chloride (the green solution that people use to dissolve copper off of gold fingers). I'm guessing this is because copper joins with two chlorides. So you add the oxidizer to steal electrons from the metals to form salts. H202 is the normal oxidizer for making copper II chloride. So when dropping copper into copper II chloride, the thing that will determine how much copper gets dissolved is the amount of "holes" that are available in the oxidizer. More Oxidizer equals more room to steal electrons from copper. Which is why you need to add more H2O2 or bubbler. 

*Copper cannot be oxidized, or dissolved by HCl alone, (so HCl will not attack copper), (note in the reactivity series of metals copper is below hydrogen, this means it will not react with hydrogen, or is less reactive than hydrogen, hydrogen is what makes HCl an acid, without the hydrogen Hydrochloric acid would just be a chloride (Cl-) no longer an acid).

*But HCl will attack or oxidize copper oxide to a higher oxidation state, so before we can make copper (II) chloride CuCL2 we first need to oxidize the copper, we can do this with oxygen, in air this is a slow process to oxidize the copper metal, and copper forms copper carbonates, the green corrosion you see on copper, but in acid like HCl, with oxygen Either from air or H2O2, the copper is oxidized by the oxygen easier, this gives us copper oxide in solution CuO, (here oxygen took an electron from the copper) now our HCl can further oxidize the Copper-Oxide or take another electron from the copper then the copper Cation joins with two chloride (Cl-) Anions to make a salt of copper CuCL2 or copper II chloride.



So a bubbler isn't actually getting rid of electrons in the solution, it's adding more Oxygen (this is the oxidizer in that case) that can steal more electrons from the copper.

*It is taking electrons, and the oxygen is what is doing it so yes here oxygen is the oxidizer in solution to form copper oxide, but also HCl is also an oxidizer here also taking electrons forming copper chloride salts dissolved in solution, both oxygen and HCl are reduced in the reaction, remember for anything to be oxidized something else has to be reduced.

*Now if I have not completely confused you I will keep trying

*So now we have copper II chloride in solution, if we have free copper metal in solution also then the CuCl2 becomes an oxidizer itself, being able to take an electron from the copper metal, the copper atom is oxidized into solution (lose of electron) forming Copper (I) Chloride,
And the Copper (II) chloride solution is reduced (gain of electron) to copper (I) Chloride CuCl, also so both of these change our red copper metal and our bright green solution of copper II chloride CuCL2 into CuCl the dark brown solution and white powders we see.

*Now to convert the copper I chloride back to copper II chloride we need to add some more HCl to rejuvenate the solution (again here the HCl is reduced, and the CuCl is oxidized to a higher state of oxidation to become CuCl2 again.
So here is the formula for what we discussed above:
2Cu + O2 --> 2CuO
CuO + 2HCl --> CuCl2 + H2O
CuCL2 + Cu --> 2CuCl
CuCl + HCl --> CuCl2 


Another question then, if people call it Copper 2 Chloride (because when you run out of oxidizers, you are left with Copper I Chloride, correct?), then shouldn't people call it Auric 3 Chloride? I've only heard people call it Auric Chloride ? And then in that case, once you heat the solution to drive off excess Chlorine, are you left with Auric 2 Chloride?

*Gold (III) chloride AuCl3 (Auric chloride) works very much like the copper above although it needs stronger oxidizers like chlorine, Nitric acid, Concentrated H2O2, or other very strong oxidizers, to oxidize the gold to gold oxide and gold is so very un-reactive of a metal, it is believe the electron is so hard to pull away it tries to go back, but once it is pulled away in the strong HCl solution (like aqua regia) the electron is held away long enough for the atom to attach to three free chloride ions (from the reduced HCl acid), so the gold is oxidized and dissolved into solution, which begins a chain reaction of more gold atoms giving up electrons.

*If we heated the AuCl3 in solution it stays AuCL3 until dry crystals (unless we heat it above something like 180 degrees), so we can evaporate it to crystals of AuCl3, if we kept heating to decompose these crystals driving off the (Cl-) we would form Au gold metal, We would not be able to drive off only one chloride from each atom of salt as far as I know to form something like Gold (II) Chloride AuCl2, I am not sure that even exists, I would have to look up to see if gold can be in the (+2) oxidation state, and if it can how it is formed… 

Now are you getting as confused as I am?


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## kkmonte (Mar 16, 2013)

LOL thanks butcher, i'll read this a few dozen times and let you know.


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## cejohnsonsr (Mar 22, 2013)

Thought it was about time I updated my progress. I wound up with quite a bit of "cemented" sediment from the copper. It was very black & had some flakes & clumps. I could see a hint of brown, but just barely. After a prolonged boil in HCl (per Harold) & a very thorough rinse it still didn't look like gold to me. My hard drive died so I haven't had access to this site or Hoke's book. (I'm using a borrowed computer now. It's not always available.) 

After thinking it over for quite a while, I decided that a 50/50 solution of Nitric Acid & water should dissolve any base metal (like copper) from the sediment in my beaker. The sediment was wet. I estimated about 5 ml of rinse water keeping it wet. I added 15 ml water & then 20 ml Nitric Acid. It reacted, which I take to mean that there was something other than gold in the sediment. When the reaction stopped the solution was blue & there was a little greyish "scum" floating on top. I added another 15 ml each of water & Nitric Acid. I didn't get any further reaction, but the greyish "scum" seems to be being slowly digested after about an hour. I'm still very cautious about Nitric Acid so I didn't get too close, but what's left of the scum appears to have a crystalline structure & also has a copperish color to it. Could this be some sort of copper "salt"? I've given the beaker a couple of swishes to make sure the remaining sediment is well exposed to the Nitric/water solution. Now I'm just letting it sit for a while in case it's still digesting non-gold metals. It's hard to tell because of the blue color of the solution, but the sediment in the bottom of the beaker now appears to be more brown like a normal SMB drop from AP --> HCl/Cl process. 

I know I have to filter, wash & rinse VERY thoroughly. I'm curious about how to wash. If I use HCl & all the Nitric isn't gone some of the gold will dissolve as it would in AR. Would I maybe be better off to just rinse it as thoroughly as possible with water, then cover the sediment with HCl & add Nitric a few drops at a time until all the gold is dissolved, then drop with SMB again? 

The starting AP material was unpopulated boards. There was no solder of any kind involved. Also, except for the prolonged boil in HCl when I washed & rinsed the cemented sediment, this was all done cold.

Any & all input & suggestions are appreciated. I'll check back as soon as I'm able. I'm assuming that if I leave it sit as is until I'm able to check messages again there should be no problem. If I'm correct, the Nitric/Water solution will only digest base metals & the gold sediment should be ok.

Thanks,

Ed


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## butcher (Mar 22, 2013)

Ed,

Did you incinerate the powders, after the boil in HCl, before going to nitric acid, if not your used nitric solution could have some gold now dissolved in it, you can check a few drops in a test tube, add HCl to the test tube treat it like aqua regia that needs the free nitric evaporated, (you can also use sulfamic acid), after deNOxing solution test it for gold with stannous chloride.

You can wash the powders in a little more dilute nitric this time using heat, if you still get color you are still removing metals, after that then you can dissolve the powders in aqua regia, using minimum nitric acid.

Heat can almost be a necessity as far as I am concerned, many reactions work so slow, or may not come to completion without it, it is not needed for every process, but I use it in almost all of my processes.


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## cejohnsonsr (Mar 23, 2013)

Thank you, butcher. I haven't incinerated anything yet. I'm pretty sure I had all the HCl out. I rinsed with boiling water 3 times. I've read tons but only actually used Nitric twice (counting this time). If I understand correctly, adding HCl to the Nitric/water solution will use up the excess Nitric? Right now I have a little less than 100 ml of the 50/50 Nitric/water solution. The blue color hasn't darkened any further & no more of the "scum" has digested after sitting over night. After I decant, will another 100 ml of HCl be enough to denox? I wish I had my own computer, docs, etc... I had this pretty much all figured out. Or so I thought. 

I'm finding that heat is almost always necessary (or at least beneficial) as well. When I heat up the next dilute Nitric wash, how much heat should I use? Enough to boil or just below boiling?

If there is gold in the current solution, it won't be much. The reaction didn't last long & very little of the original sediment was consumed/digested. I think for now I'll decant the Nitric solution(s) & subsequent rinses into a separate container & deal with them after I've restored my own computer so I'll have access to all the info I've accumulated & organized for this purpose. That way I'll only have to deal with 1 process at a time. (That seems to be about all I can manage at this point in my education.)

Thanks again. I'll check back & post updates as I'm able.

Ed


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## butcher (Mar 24, 2013)

Ed, 

I haven't incinerated anything yet. I'm pretty sure I had all the HCl out. I rinsed with boiling water 3 times. 

Say I wanted to remove tin with HCl, and then I think I could "wash out the HCl out" with boiling hot water, then I decided to remove some copper from my gold, but I was not ready to dissolve my gold yet, what would happen if I went straight to nitric acid now?

You cannot just wash the effects of HCl out, not only would their be traces of HCl (especially if powders), but there will be metal salts of the HCl, these metal chlorides, when come into contact with hydrogen from an acid (like hydrogen in HNO3) would convert back to HCl, now I will have some HCl mixed with my HNO3, so I will dissolve some gold.

This is one reason we incinerate, when changing from HCl to nitric (to dissolve base metals), to remove the HCl or convert the base metal chloride salts to metal oxides.

silver chloride is volatile, if heated strongly like when incinerating or roasting the powder to red hot (or melting), and much of the silver will burn off going up in the white smoke, gold when incinerated with chloride salts, some of the gold can also become volatile as in these temperature gold chlorides can form from the chlorides burning off chlorine gas, some gold can be lost with this gas, usually leaving yellow stains where it condensates to cooler surfaces, sometimes purple stains can be notices where tin condensates also, to try and convert the chloride salts to hydroxides then oxides, and to remove some acidity I will usually give my powders a wash in a solution of sodium hydroxide and rinse the sodium chloride salts well with water, drying and crushing, before incinerating.

If I understand correctly, adding HCl to the Nitric/water solution will use up the excess Nitric? Right now I have a little less than 100 ml of the 50/50 Nitric/water solution. The blue color hasn't darkened any further & no more of the "scum" has digested after sitting over night. After I decant, will another 100 ml of HCl be enough to DeNox? I wish I had my own computer, docs, etc... I had this pretty much all figured out. Or so I thought. 


Adding HCl to nitric/water solution will not use up the nitric or it will not use up the HCl, but it does form some gases nitrosyl chloride NOCl , nitrogen dioxide NO2, nitrogen oxide NO, chlorine Cl2, these gases will react with metals in solutions some will leave the acid solution and some will mix with the acid, if water is involved some of these gases will stay in solution but can convert back to acid, if dilute and cold these cases stay in solution much longer, these gases are also important in solution when we make aqua regia to dissolve gold, this is why we do not premix aqua regia before we are ready to use it.

So mixing HCl into nitric does not DeNOx, it just makes aqua regia, so it will not use up nitric acid.
What can use up nitric is its action on oxidizing metals, in Aqua regia the nitric oxidizes gold along with the strong gases mentioned above, so we can use up HNO3 by dissolving gold (and actually we could use up our HCl, if we did not add an excess like we do), (Note if we had more nitric in solution and had a limited amount of HCl, we could actually use up all of the HCl and then we could not dissolve more gold, what gold we did have would be dissolved in the solution of excess nitric acid), heat can also assist in using up the acid the acids reaction can slow or seem to stop in cool or cold solutions, when heated these same solutions can still dissolve a lot more metals, and concentrating the solution the solution will dissolve more, also a hot solution can hold more metals in it that the same solution if it is cold…

Heat can be not only extremely useful, but many time just downright a necessity.
How much heat I say really usually depends on the process, what stage of that process, and the reason for the heat, or the reason to lower the heat.
Hardly ever do you boil a solution.

You never want to boil a solution of aqua regia with dissolved gold.
Sometime I may bring a solution up to almost boiling and hold it there, then lower the heat to let powders settle well which may take some time, with the goal of keeping the solution as hot as possible, but also not so hot that it stirs the powders, I may do this when I am using boiling hot water to dissolve the lead chloride salts from silver chloride salts, when the very fluffy insoluble silver chloride settles, I will decant the soluble (in very hot water only) lead chloride.

Sometimes I may to measure how hot a solution is and I may need to control the temperature within a certain range for best results, or the temperature can be indications as to what I have or what is happening, like when distilling solutions.

Sometimes I cannot heat a solution as much as I would like to and I have to settle for using a very slow low heat, making the process seem to take forever, like when drying meal powders before being able to incinerate, where if I raise the heat too high gas bubble rising to the surface of the metal mud will sputter and spit my mud all over the place.

Sometimes I may be able to evaporate my aqua regia below boiling, but have to watch it closely as it concentrates, as there is a point in concentration where nitric gasses wanting to come out of solution in mass or all at once, if you kept the temperature this high the pot will boil over foaming all of your gold out of your pot, you can see tiny bubbles form around the edge of the solution just before this happens and you can lower the heat until you are past this point, then you can raise the heat again, (after you lose your gold and have to process 5 gallon pail of dirt and leaves, to get some of that gold back, you will have learned a couple of lessons, like to keep an eye on your aqua regia when evaporating watch for the bubbles in concentrated solution and or lower heat, catch basins are easier to clean up than the dirt, and trying to get your gold back out of the dirt is no fun at all.
I guess what temperature to use is one of those things you will learn not only with study but also by doing.

I do not know how much gold you may have in the solution, you do not either unless you test it, gold is rare, so you really want to keep all of it you can, stock pots are a great precious metal trap, for traces, a great piggy bank, every refiner needs a good penny bank, as sometimes those penny's can mean whether you make a profit or go broke. 

We all learn from our mistakes, but it is better to learn as much as we can through study, so that we are not just learning to make more or better mistakes, mistakes yes we can learn from them, but if this is all we learn from, that can very well be all we get good at, is making mistakes, and believe me when I say mistakes are very costly, so studying and getting a better understanding can help us learn to make less mistakes, study and practice can help us to understand better not only how not to make mistakes, or prevent them, but also how to fix them when we do.

Ed, I hope this helps and you get that computer going.


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## g_axelsson (Mar 25, 2013)

I accidentally got some gold to cement out on my scrap  , there is two pictures in this thread.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=60&t=17697

Göran


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## cejohnsonsr (Mar 25, 2013)

Hi butcher. Thanks again for a lot of good info. I couldn't believe what I had written when I read it again as quoted in your reply. I don't know what I was thinking, but I'm pretty sure I got my thoughts & writing mixed with 2 subjects. The good news is I didn't add HCl to the solution. I did settle & decant the blue solution & "scum" from the Nitric bath. I replaced it with a fresh 50/50 Nitric/water solution. Haven't had a chance to apply heat yet. We had a snow storm & I have to be able to move outside for positive ventilation. There was no reaction to the fresh solution & after more than a day there has been no color change. The solution is still perfectly clear. I can see the sediment more clearly now. There is fine powder & some clumps. It's still quite a bit darker than I've seen from other examples, but whereas it was black, it is now definitely brown. Just very dark brown. As soon as the weather permits I intend to heat the solution to see if any more base metals will dissolve. I guess after that, provided no more reaction occurs, I can rinse & move on to AR. 

If I have my head on straight this time, the hot Nitric bath & subsequent water rinses, will finish removing anything that's NOT gold. Then I'll cover the remaining sediment with HCl, heat gently & add Nitric a few drops at a time to dissolve the gold. I should be able to watch the gold dissolve & see when the reaction stops. If I do this right this time, the Nitric acid should be completely consumed in the process of dissolving the gold. I don't know precisely how much gold I have here. Maybe 1 gr. I think it should take 1 ml of Nitric (max) to dissolve 1 gr of gold (Hoke, lazersteve). So if the reaction stops & I still have undissolved sediment, I should probably add HCl to see if that finishes it up before I add another drop of Nitric.

All the solutions & filters from this have been segregated so I can treat them separately later. In fact I've kept everything so far. I have AP still working, spent HCl/Cl that was dropped with SMB, the solutions & rinse from this attempt & some rinse water. All segregated by process used. The one exception is the solution this gold was cemented from. After I cemented with copper I then cemented with steel & neutralized with baking soda until the PH was about 8 or 8.5. No problem with disposal. The local recycling/disposal center would have taken it even if I hadn't neutralized it as long as it was labeled to their specs. Everything I'm doing so far is more for learning than for actual production so I'm working with very small amounts of everything. 

Wish me luck.

Ed


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## butcher (Mar 26, 2013)

Ed, from reading your last post it sounds like your education will be better than luck, but I wish you luck anyway

One point, when you dissolve the gold, after about half of the calculated nitric acid reacts, and the initial reaction slows, I would add heat heat this will help the acids involved become more reactive, slowly concentrating these acids more metal will dissolve, add the nitric in small increments, as the solution concentrates, by the time your gold is almost all dissolved, you will have used most of the nitric acid you calculated and the solution will almost be concentrated, just a little more and it will be concentrated (for the first evaporation), at this point add a few drops of sulfuric acid, (you could add a little sulfamic acid solution, instead of sulfuric acid if you have it, it can help De-nox and will make some sulfuric in solution from the reaction), finish concentration, then you should have an orange gold chloride concentrate, at this point a little HCl to wet, heat until the water you had in this added HCl evaporates (HCl is 32% acid, 68% H2O), this will also help to remove any free HNO3 (you may see some red NO2 fumes if any),the added HCl also insures plenty of chloride for the gold, this second concentration will not take long, do this HCl and evaporation one more time, after this you should have pretty well used up all of the nitric in solution, or vaporized of any excess, now you can lower heat and dilute, and let it sit overnight, for any silver chloride or lead to settle out, before decanting and filtering solution into a clean vessel for precipitation of your gold...


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## cejohnsonsr (Mar 26, 2013)

Thanks, butcher. I don't trust to luck very much either, but I'll take what I can get! 

I printed out your last reply so I can have it on hand as I'm working. I do have some sulfuric on hand. Rooto. Now I have one more question. 



> after about half of the calculated nitric acid reacts, and the initial reaction slows, I would add heat



When you say, "add heat", do you mean, "increase heat"? When I get to this point, it had been my intention to heat the HCl until I get a little steam & some condensation on the watch glass. Only then was I going to add any Nitric Acid & only a few drops so I could watch it react. And just to be very complete, I intend to do this for approximately 1 gr of gold in a 1000 ml beaker using 100 ml HCl & Nitric Acid added 3 or 4 drops at a time up to a maximum of 1 ml. No water. I don't think I need to dilute the HCl for this reaction. 

Looks like the weather might be clear enough for me to do the Nitric bath today. No hurry for the rest.

Ed


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## butcher (Mar 26, 2013)

Ed, 
when I begin heating will usually depend on the materials I am working with, at first the reaction can create a lot of gas and NOx fumes having water in solution and not a strong heat can help to keep these fumes in solution doing more work (NO2 dissolving in the water to re-form more HNO3 in solution), also powders if treated with acids can be quite reactive, solid metal pieces will be less reactive, and you also generate some heat by the chemical reaction alone, basically you can use your own judgement when to begin adding heat, but starting without heating the beginning, can make the acid go a little further, and can help to keep fumes down somewhat, and depending on material can be less reactive, and it does not hurt to raise the heat as needed after you see how the initial reaction reacts, also consider sometimes when acids are added there may be a delayed reaction, taking a few minutes for the acids to get busy as the begin building their own heat in the reaction, and act on the metals.


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## cejohnsonsr (Mar 26, 2013)

Surprising/disappointing update:

Heating the Nitric/water solution caused most of the sediment to be consumed quickly. The solution turned a very light, clear blue/green. What is left floats & is being very slowly consumed. I know there's gold in here, but it can't be very much. No where near the 1 gr I had predicted. The remaining material looks almost organic. Like fine grass clippings. I don't know how that could be. Is it possible that the copper split bolt I used to cement with could have contained tin? If so, will it be consumed by the Nitric? The reaction is in progress now & I need to return to monitor it. I'll post more later when I have a chance.

Update:

I wrote the previous update at 2:03 PM. It's now 4:20 PM. About 5% of the original material remains. The reaction continues. Digestion seems to be continuing slowly. I'll let it go as long as I can. I'm curious to see what will be left & if there will be any gold at all. If it's not gold, what was cemented? I admit to being a bit befuddled here.

Ed


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## cejohnsonsr (Mar 28, 2013)

Well I let this run as long as I could. After a couple more hours nothing more had been digested. I let it sit to cool over night & took these pics. One shows the color of the solution (pale blu/green) & the other shows what was left of the cemented metal. I'm guessing it must be tin. Apparently my copper split bolt was alloyed. I decanted the solution through a charmin plug & saved both the liquid & the filter in case I might want or need to try anything else or find some way to get any more use out of it. I may not have any gold from this exercise, but I did learn. One thing I learned for certain is to make sure I have pure, clean copper. 

Thanks to all who helped. (butcher) Now on to my next project.

Ed


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