Trouble with 3-1 ratio making AR using nitric substitutes

[butcher]

The sodium sulfate should not interfere with the gold, (note: it is not sodium sulfite which would precipitate gold), now if silver was in this solution I can see where the silver could form silver chloride as well as silver sulfates, also as stated above the solution would need water to keep the salts from forming.

Note this is a poor mans solution that cannot get HCL or HNO3.


Also note, HCL and HNO3 could be made separately and the majority of the salts removed (or they can be distilled separately for a very pure product), and mixed when you needed aqua regia.

I have not tried this to verify anything yet, at this point it is just the formula and the calculations.

 

[dangerousdane]

Hi every one. I am not exactly a newbie having been reading and absorbing this massive gold mine of information since last august. I have also done some refining and have a 12 gram button of double refined gold to show for alot of time and effort and expense. Butcher PMed me and asked for help regarding the discussion mentioned above due to the fact that I taught HS science for a few years. Butcher , however it has been 12 years since I taught. I can follow it well enough but to generate the discussion you led there let alone critique it is asking for real trouble and confusion from me. I have kept my mouth shut and read and learned for a reason. This forum has so much to give it is like mining itself. it does not come without work and effort and you don't know when or where you will find something valuable. I have not posted up to now because I feel that I need to give something back before really belonging and I haven't been able to do that yet but I will soon.
D'dane

 

[butcher]

That pretty gold button, speaks for itself, it shows you have been doing your home work, I was hoping you could help me with my homework, which I am sure you still can with your experience, we all have different experience in life we can share, I just cannot wait until you feel like you can share yours with us.

Welcome to the forum, I will wait patiently while trying to struggle through these math problems.

 

[cableman]

You guys are awesome. I really want to use the sodium nitrate instead of straight nitric acid due to the cost. And Butcher, I had found one of those molecular weight charts (think that's what you call them) and came up with about 1.34 grams of sodium nitrate to one ml of hydrochloric acid. But now that is a one to one mix so I would only use 1.34 grams to 3ml hydrochloric for aqua regia. Thank you all for your input and even thought I am a newbie I still know enough not to mix all at once.LOL

I probably should have started another topic for this but since it was brought up should I have a problem with silver chloride using this method. It was my understanding that I would just stir and finally let the silver chloride mud settle to the bottom and pour my solution off leaving the silver chloride behind for other uses. I then thought I used urea to lower the ph and get rid of excess nitric acid before precipitating my gold with SMB and of course rinse and rinse before melting.

I wanted to try this method on some gold plated pins I have collected before trying on my CPU's so if I have something wrong please correct me and thanks so much for all you guys helping.

 

[butcher]

You guys are awesome. I really want to use the sodium nitrate instead of straight nitric acid due to the cost. And Butcher, I had found one of those molecular weight charts (think that's what you call them) and came up with about 1.34 grams of sodium nitrate to one ml of hydrochloric acid. But now that is a one to one mix so I would only use 1.34 grams to 3ml hydrochloric for aqua regia. Thank you all for your input and even thought I am a newbie I still know enough not to mix all at once.LOL

With that ratio, you have too much unconverted sodium nitrate. You will not be converting all of the sodium nitrate salt to acid, you not only will have excess sodium nitrate but also excess sodium chloride later to deal with, as NaNO3 would be in excess, which could give you trouble later, with trying to get your gold back after you dissolve it, as you will have excess nitric in solution forming during your evaporation process to remove excess nitric acid, before you could precipitate your gold. (From the excess sodium nitrates forming nitric in the acid during the evaporation process later as the solution concentrates), and with added salts NaNO3 and NaCl, you will have to use the HCl in the end any way, if you use too much sodium nitrate, to remove the nitric (adding HCl during the evaporation process, the HCl will need to be added to convert the excess sodium nitrate in solution, then HCl will be needed to keep the solution from forming crystals, salts of NaCl and salts of NaNO3, when evaporating [excess sodium nitrate and sodium chloride]), it would be better to add that HCl in the beginning where it would do more good. Forming aqua regia to dissolve the gold, than at the end where it is just wasted trying to remove excess nitric acid (to evaporate NOx gas from solution), the added sodium will also cause some trouble normally with the evaporation process (wanting to form NaCl with evaporation easier than when we use acids to make aqua regia with the normal method).

If anything I would want excess HCl and limit the NaNO3 salts.

I probably should have started another topic for this but since it was brought up should I have a problem with silver chloride using this method. It was my understanding that I would just stir and finally let the silver chloride mud settle to the bottom and pour my solution off leaving the silver chloride behind for other uses. I then thought I used urea to lower the ph and get rid of excess nitric acid before precipitating my gold with SMB and of course rinse and rinse before melting.

You would have some excess chloride, so more silver could stay in solution in the concentrate chloride solution, but after free nitric is used up, and solution is diluted the silver would precipitate as silver chloride.

My suggestion is, do not use excess sodium nitrate in your recipe as you suggest above.
Use gold to use up the nitric in solution, which can be done with using the ratios I stated, adding a little excess water and HCl to account for evaporation, heat your solution while dissolving your gold, leave a little gold undissolved (using up all of the nitric in solution), this way you use up the nitric in solution in the beginning.

Or you could use the gold later, as Harold suggests adding a pure gold button during the evaporation process to remove unused HNO3 from solution.

With pins you have mostly copper and very little gold, this would make recovering the gold hard to do, almost impossible especially if you are new to this, it is never a good idea to dissolve base metals with gold when you can keep from doing so. (This can be done if you know how, but it is asking for trouble, even when you know how, you are going to get higher lose of values, recovery is more difficult, and you are just asking for trouble or looking for ways to lose your gold, here you have to use acids to dissolve the copper any way, so why make taking a chance of losing your values, and giving your self more trouble to dissolve the copper, why not make and use nitric acid, (or use another method to dissolve copper without dissolving your gold).

With CPU's the base metal to gold content ratio is more suited to doing this with just minor problems.

Urea in my opinion is just a bad idea, especially here where your solution is already loaded with salts, why add another salt and contaminate the solution further, and take the chance of forming something dangerous.

Note:
UREA CAN BE DANGEROUS TO USE :!:
Why would anyone use it where they do not need to I have no clue, and people who suggests its use should also quote the side products that can form, so the new guy will understand how he could possibly make ammonium nitrate, which could become dangerous in these metals or solutions.
My opinion Urea is just not needed or a bad idea.
Why take the chance of making an explosive substance or compound, when there is no need?
We have been taught much better methods to deal with nitric here on the forum.

Urea will not destroy HNO3 nitric acid; it can destroy nitrous acid HNO2 or NO2 in solution.

 

[lazersteve]

Urea is not needed for refining, it's best used on the yard as a fertilizer.

If you are too heavy handed with nitric and want to chemically destroy the excess nitric, them use sulfamic acid as described in the Guided Tour--> Reaction List.

Steve

 

[cableman]

I tell you what Butcher, you are one smart guy. I have seemed to get a lot of interest in this subject but let me tell you something about using this sodium nitrate instead of nitric acid (I guess we all want to due to the cost). I have read several posts with all different mixture levels and I have of yet found one that they were really satisfied with.

I am getting some nitric acid!! This was my first attempt at gold recovery so I am not too upset since I got some experience and got most of my equipment together and even have a little system started. The main problem with this method is the salts left behind. I broke up 4 or 5 ceramic cpu's (5.5oz) and I think I started with about 200-250ml muriatic and about 5 grams of sodium nitrate and 30 or so ml water. I got this ratio from a post somewhere. Thing is we are using weaker materials than intended for AR so I ended up adding a little nitrate even with the heat and kept it near boil for at least an hour. I ended up with some really black solution. let it cool and sit overnight, just now heating back up to add urea so I can try to precipitate with SMB. I got some real golden clear liquid with my washes and put that separate. I added urea and smb and got very little gold, which was to be expected since it was the wash. I still have the broken cpu's in original container with a lot of unknown salt. I didn't think there would be enough silver to worry about so I speculate it could be undissolved sodium nitrate. Until I figure it out it is going into slop bucket and I will crush cpu's evem more for another run.

I wonder what the main solution is so black for? I am going to add urea and smb to see what happens. I know there has to be a couple of grams or so of gold in it so I am trying to work it out without junking it up. Any ideas would be appreciated but the main thing I think about this method is the salt to deal with. It could be some kind of silver chloride but I don't know how to tell. I will update what happens with my main solution unless I get some advice first. I may let it sit overnight to do some research on it. I have already added urea but it needs a little more and I need to make two containers of it for fear of splash over. Didn't intend to make that much AR just happened in order to get it strong enough. All comments and advice welcome. You guys are the greatest. This is the best forum I have ever run across on any subject. Please give me best advice on making my waste solution safe for when I am through. Thanks to all you guys. I will add some pics. I am outside on my laptop and I don't have the camera program on this one. Will add pics when I go inside.

 

[cableman]

Sorry Steve, didn't see your post until I started. Got that formula from reading posts where they were trying to keep costs down by using an alternative to nitric acid. I see now what you mean about the salts. I did however decide to begin with some ceramic cpu's. I thought they would be a better first try without other metals to deal with. I did make my AR a little strong just like you said I would and I now see the disadvantages of using urea. A lot of people put that in their procedure in their post without explaining alternatives. Maybe they don't know that much to begin with either. Anyway I guess you read my post above and see I made it through my first experience although I haven't precipitated the gold yet. The two yellow washes are just that. I think I got all the gold the first run. I just didn't understand the black color but I think maybe it came from the black off of the ceramic cpu's. I included the pictures of my results so far and my stannous chloride test turned out showing from left to right the two washes and on the far right my main solution which if I read it right has a good bit of gold in it. Going to do a lot more reading and do some fingers before I try the pins (they can wait). The black color in the main solution was not so dark once I poured it into another container, it just looked darker than it was.

 

[butcher]

Poor mans aqua regia is of coarse not as good as true aqua regia made with pure acids, but it will dissolve gold, and gold can be precipitated from it. If you were just dissolving gold the sodium sulfate would not interfere to much of any degree, the gold would dissolve, gold will not form a sulfate in this solution, after the gold was dissolved the solution can be filtered, if you wanted to you could even chill the solution before filtering to help remove some of the sulfate salts, the gold could then be precipitated from solution.

The poor man types of aqua regia I would normally use in a recovery process more than a final refining process,
Although you could use it in the first refining, but I would still want to do the last refining in good clean acids.

You cannot make aqua regia and store it for later use, or you cannot distill aqua regia to purify it, because it would destroy it, but you can make nitric acid and distill it, you can also make HCl and then make your aqua regia from these two acids, to get a more pure aqua regia, HCl for most all of use is cheap and easy to get, so it is just better to buy it, unless you cannot, nitric for most of us is harder to get, and can be made and distilled at home, if you use homemade nitric on silver it would need to be distilled to remove the sulfate salts from the nitric acid, just freezing the nitric will not remove all of the sulfate salts, silver will form for the most part insoluble silver sulfate salts.

Poor mans aqua regia made with HCl and NaNO3 would be better because it would not contain the sodium sulfate salts, as compared to the Poor mans aqua regia made with the NaCl + NaNO3 + H2SO4 method. Better than both of these would be aqua regia made from distilled homemade nitric acid HNO3and HCL, and of coarse best of all would be store bought nitric acid and store bought HCl acid to make your aqua regia.

Sometimes HCl and NaClO (bleach), may be preferred for it ease of dealing with when dissolving fine gold, or even the HCl + 32% H2O2.

Sometimes it may depend what acids you can get or cannot get, what type of materials your trying to recover gold from, which chemical or process you may choose, it is nice to have alternatives at times even if they would not be our first choice.

 

[cableman]

I see the error of my ways now. I have learned a lot by the mistakes I have made in my first attempt. First off let me correct the formula I used. I don't know how I accidentally put the wrong amounts of chemicals I was going to use down in the earlier post but now I see why you were so worried about me using too much sodium nitrate. The wrong number on my amount made it an incredible ridiculous amount of sodium nitrate. It was really 1.34 grams of sodium nitrate to 250 ml of hydrochloric. I still ended up using too much just like everyone said I would it being my first time. I really messed up by using urea. I don't remember where I got that information for using urea in this process but you are right. After running a batch and reading some more and seeing what happened I realize that urea is not needed at all. I might as well throw it in the yard.

I have managed to straighten up half of my mix but I still have a problem I don't know how to deal with. I am ordering nitric acid immediately and will properly dissolve off the unwanted metals with nitric before making AR and dissolving my gold. Right now I have managed to get a great deal of PbCl2 (lead Chloride) in the half of my solution that I have not finished. I have gold flakes mixed all in it. I am unsure of which method is best to remove this. If you have any advice please tell me my options for fixing this mess. I may not be able to recover the gold but I need to at least get this solution to a safe state to dispose of if gold recovery is no longer an option. I can also make a little homemade nitric to use for now until I can get my chemically pure nitric. I don't know how long it will take to ship and I am looking for best price before I put in my order today.

I have done a lot more reading and realize where I made a lot of mistakes. I am continuing my research and feel a lot better about how I will approach my next attempt. I see the need for nitric and the trouble that using urea brings. Now that I know what I do, I can't believe that some person actually posted a formula for gold recovery the way I was told to do it and using urea. I double check my information now. If you could give me some advice on how to proceed with the removal of this lead chloride I would be most grateful. The only chemicals ever present were muriatic acid, sodium nitrate, urea, and the broken up pieces of 4 or 5 ceramic CPU's. Thanks in advance for any advice. I will not make these mistakes again. Learning the hard way like this has hammered in a couple of important things. I need nitric acid to do this with and never use urea again. Also I got straight on the correct steps in the procedure of removing the unwanted metals first before dissolving my gold.

 

[butcher]

You can have several salts mixed with your gold at this point, luckily they are fairly easy to separate from the gold.

Most salts are water soluble (excess sodium nitrate, urea sodium chloride and so on) these would dissolve in cold water, better if hot.

Hot water not only dissolve more of the water soluble salts but can also dissolve lead chloride salts, lead chloride is not very soluble at all in cold water but in boiling hot water becomes very soluble.

silver chloride is not soluble in cold water or hot water, but it is very fluffy and will float around easily, so if we are separating lead and silver chloride salts we want the water boiling hot, and keep it that way (but not so that it circulates or stirs the salts), but very hot, and giving time for the silver chloride to settle, depending on how much of each salt we may have to use more than one wash cycle.

copper I chloride can also be an insoluble white salt in water, it will dissolve in a solution of HCl, if we have a lot of copper salts the solution will turn dark green to brown, if only a small amount it will turn green or blueish.

Lead sulfate is not soluble in water hot or cold, or silver sulfate is fairly insoluble, for these if they were with your gold I would incinerate the powders and wash with HCl and hot water to form soluble chlorides.

A good study is the solubility rules, and then looking at charts of the solubility of these metal salts, noting solubility in water or acid, and pay attention to temperatures they may be soluble in, this will help you get a better understanding how to deal with solutions or problems when you run into them, also small experiments like Hokes book teaches can help you understand how to deal with metals how they react, what they look like and how to separate them...