Need Advice on Using Homemade Nitric...Please

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juxtaposedsoul

Active member
Joined
May 21, 2011
Messages
38
Location
Richmond, VA
Hey Guys,

My young refining career is about to come to an early end if I don't figure out how to get all of my silver to dissolve. Heck, at this point I would be thrilled to get 50% of my silver to dissolve. What am I doing wrong? I am using homemade nitric because chemical supply companies only sell to businesses. I use 500ml boiling distilled water, to which I gradually add 700 grams of sodium nitrate crystals. Once the solution is thoroughly saturated I let it cool. I then slowly add 280 ml of sulfuric acid, a little at a time. Next, I let the salts drop for 20-25 minutes. Then I transfer the liquid to a dense plastic container with lid and freeze for 3 hours. I do not pour the salt into the freezing container, but additional salts develop while freezing, so I transfer the finished acid to yet another bottle and leave the new salts in the container used for freezing. My understanding is that I should have about 50% strength nitric from this procedure.

Here are my questions, to which I would be extremely grateful for answers:

1. Does this process actually make 50% nitric acid?
2. What is the proper ratio of acid/distilled water to use per gram of sterling silver (I know it's 1:1 with 70% nitric)?
3. Why is this acid so ineffective, as I have tried every ratio from 1:0.5 to 1:2, with similarly disappointing results?
4. Do I need to add pure silver powder to my acid, and if so, how much?
5. If the homemade stuff doesn't really work (I've tried and tried, with heat, too) where can I buy some real acid?

I'm frustrated. I have about 1/2 pound of partially digested sterling from several batches that never fully dissolved. Please guide me, I need your help. Thank you.
 
You have a little bit too much water and a little bit too much sulfuric acid in your mix. You should be using 100ml distilled water, 170g sodium nitrate & 56ml sulfuric acid. Where are you buying your sulfuric acid at. You should also be allowing more time for your first salts to drop, and you should leave in your freezer overnight and then filter your solution. If you are adding distilled water to the finished acid and trying to process with that you have a very weak acid you are using.
 
Barren Realms 007,

Thank you for the advice. I will try the proportions you suggest on the next batch of acid I make, probably this weekend. I buy "Liquid Fire" drain cleaner at Ace for the sulfuric acid. Just to be clear, if I follow your recipe and proportions, I will achieve a usable grade of nitric? And, are you saying that I should not use any distilled water when digesting sterling silver, just the acid alone?
 
Thanks again. I will try to process a small batch of silver without adding distilled water. In fact, I will try it now, although it is getting late. I'll post the results tomorrow. Your help is very much appreciated. Thank you.
 
my advice would be to distill any homade nitric used for silver, the by product of homade nitric is sulfates, (or chlorides if using HCL as the acid),either of these will give you problems with dissolving silver,(seperating nitric and chlorides would be harder so stay away from making HNO3 with HCL if using it for silver).

how much sulfate left in solution even after freezing would be questionable, by distilling the nitric you leave these salts behind in the reaction flask, silver sulfate is insoluble so even if you dissolve the silver you could be making a portion of the silver precipitate out as sulfate's.
 
Butcher,

This is ringing a bell! Would this sulfate you mention take the form of a grayish powder at the bottom of my beaker after dissolving my silver. This grayish powder (see my other post) is always present after digestion. Always. It is a pain in my backside. A small portion of this powder, say one gram, will turn 5 gallons of water gray. Is this sulfate, and is it because of my home-brewed nitric?

I am a little intimidated by the idea of distilling. It seems quite complicated.
 
sounds like the culprit.
Actually distilling is really simple, heating a vessel and capturing the gasses or condensing the gasses, I do this in homade setups, but the chemical distilling equiptment is relatively inexpensive.

Most mountain men from where I was raised knew this art, they worked by the light of the MOON.
 
butcher said:
sounds like the culprit.
Actually distilling is really simple, heating a vessel and capturing the gasses or condensing the gasses, I do this in homade setups, but the chemical distilling equiptment is relatively inexpensive.

Most mountain men from where I was raised knew this art, they worked by the light of the MOON.
Click to expand...

Moonshine and nitric....HMMM which to choose. :mrgreen:
 
Hey Guys,

I just tried a small batch of 50 grams sterling with the 50% homemade nitric and no additional water. I used 1.3 ml of acid for each gram of silver. You were right Barren Realms 007- it worked like a charm!Wow...what a beautifully violent reaction. Much more of the nasty reddish brown fumes than ever before (they were outside while I was indoors watching) and all the silver gone! Success!!! I may pull an all-nighter just to get my powder drying. Thank you. I was using my original recipe that is light on the sodium nitrate, but I intend to make a batch with the recommended proportions this weekend, which I am sure will work even better.

As for distilling, I know it is my next step. I am not rushing into it. I intend to refine over 20 pounds of sterling so I will need a good acid to make my life easier. After I learn to distill I will go on to the next step and begin building a parting cell. Thanks for all the advice. You guys are great, all of you. Now, I think my solution is cool enough to filter and start dropping silver. Gotta go! See ya.
 
Update and new questions:

First of all...thank you for the corrected proportions BarrenRealms007, I made a trial batch and it does work better. I still cannot use DH20 when dissolving so my per gram increment of nitric-to-sterling is still somewhat suspect. I am trying 1.5ml of "undiluted" homemade nitric per gram today but I suspect the copper content of roughly 7.5% may necessitate using slightly more. I know experimenting is never a bright idea and one should stick to the time-proven methods and measures but I do not see any clearly defined formulas or amounts for dissolving sterling in the type of non-distilled nitric I am currently making. I will post my results next week after I hopefully find the ideal increment. Secondly, thank you Butcher and it is quite clear that since I am unable to just buy lab grade or even tech grade nitric I will indeed need to learn the process of distilling. I can see it is mandatory. I am not rushing myself but I have begun research on the forum and elsewhere. I will post my intentions and process before actually doing it to get some feedback beforehand. You know the saying-an ounce of prevention....

New questions and again I beg forgiveness for being a novice and asking the most basic of questions:

1. Can silver chloride precipitate as a grayish cottage cheese very similar to silver cement with the only noticeable difference being the presence of many tiny silver specks in it?

2. The silver sulfate issue- I am saving all of this insoluble dark gray powder in a jar with DH20 until I learn to deal with it. My best estimate is I now have about 30 grams of it. Is this what I should be doing?

3. What exactly are the "salts" produced when I make my homemade nitric and how to best deal/dispose of them. I now have roughly 100 grams of these pesky salts in a HDPE container and would like to see them gone if they are of no further use.

As always, thanks in advance for the help and for bearing with my ignorance. Also, I hope I am posting in the right topic as I continue this thread but think it might belong in "Chemical Processes".
 
Clarification: On question number 1 I should specify that this gray precipitate with lots of shiny silver specks or crystals is dropping with copper from a clear solution that I siphoned off the top of my "silver sulfate" storage jar. Thanks.
 
Your question on gray precipitate with shiny specks dropping from silver nitrate with copper sounds like elemental silver (resembles pepper to me).

Copper would also precipitate any silver from a sulfate solution as elemental silver forming a copper sulfate solution, but silver sulfate being so insoluble, I suspect that was residual silver nitrate solution before using the copper buss bar.


Silver chloride or any silver sulfate can be filtered from silver nitrate solution before precipitating the silver with a buss bar.

Save anything until you know what it is and how to deal with it to get any values or how to dispose of safely.

saving powders I would give few wash's with boiling water (keeping solution very hot till all powders settle, then neutralize powders with hydroxide solution, dry them, roast them red hot, store in sealed jar with label of where they came from and what you suspect they are, then search for Hokes book and do her experiments of getting acquainted with metals and acids, you will soon learn to deal with most anything you will encounter.

Edit to add: the salts (byproducts) from making nitric acid are very useful, to me it is just part of the chemicals I bought when I bought sulfuric acid and nitrate salts, why would I want to dispose of a chemical I may need to go and buy for some other process, or for some other chemical reaction I may want to do. these are sodium or potassium sulfates or bisulfates depending on your process for making your nitric acid. very useful in our field of recovery and refining of precious metals.

Hope I explained this proper to be understandable.
 
Hi Butcher,

Thanks for the insight! I suspected the salts were sodium sulfate and I guess I need to figure out how to recycle or reuse them. As for the precipitate with the tiny silver flecks it looks a little different than the regular silver cement that I get but I, too, think it looks like a silver powder. Tomorrow I will melt a small quantity of it to see if it becomes metallic silver. I suspect it will. I have been keeping my sulfates and other by-products as Hoke suggested. I keep everything including all my used filters, etc. I need to learn how to deal with that stuff before it piles up too much. As always, your advice is greatly appreciated.

On another note, I spent this past weekend running experiments on how to dissolve .925 silver in 50% homemade nitric. As you surely know that is completely different than just dissolving pure silver in 70% nitric and an equal amount of DH2O. I came up with some really interesting results and a "new" method. Do you think this forum would be a good place to post those results, and to describe the method I found to work best, or should I just keep the information under my hat and not risk confusing anyone?
 
silver salts when melted can burn off in smoke making you wonder where your silver went.

silver chloride will need conversion to elemental silver.
silver sulfate can be melted in flux with Iron to scavange the sulfates.
 
juxtaposedsoul said:
On another note, I spent this past weekend running experiments on how to dissolve .925 silver in 50% homemade nitric. As you surely know that is completely different than just dissolving pure silver in 70% nitric and an equal amount of DH2O. I came up with some really interesting results and a "new" method. Do you think this forum would be a good place to post those results, and to describe the method I found to work best, or should I just keep the information under my hat and not risk confusing anyone?
Click to expand...

I'm not sure the appropriateness, but I for one would love to hear more methods :) I want to remove the impurities from a silver-containing coin for practice, and have access only to nitrate salts and H2SO4&HCl as well. I expect that the information is valuable as long as it's not dangerous? And it would give others in the forum the opportunity to contribute improvements or point out hazards, or to point out if it's already covered here somewhere ;)
 

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