Anywhere to buy nitric reasonably cheap?

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Elemental said:
I use a silver cell for after chemical refinement to get the silver from ~98-99% pure to four 9's fine silver. Putting sterling silver into a silver cell will quickly foul the electrolyte with copper nitrate.
Click to expand...
Ah ok so then it is only used for getting to 9999 silver really. So the most economical way to refine sterling to 999 is dissolving with nitric acid.
 
Here is the basic recipe that I follow. Although I have a spreadsheet now to calculate distilled water/acid/sterling ratios.

Elemental's Steps for Refining Silver
  1. Melt sterling silver and slowly pour into water basin to make silver corn-flakes. (This step can be skipped, but dissolving the silver takes longer)
  2. Measure out 110 grams of silver corn-flakes and place in a clean 500mL beaker.
  3. Add 150mL of distilled water to beaker.
  4. Heat the beaker on a hot-plate to 80 degrees Celsius
  5. Add 50mL of 70% concentrated nitric acid
  6. Cover with a watch glass allow reaction to proceed until no more brown fumes are generated.
  7. Add 50mL of 70% concentrated nitric acid
  8. Cover with a watch glass allow reaction to proceed until no more brown fumes are generated.
  9. Add 50mL of 70% concentrated nitric acid
  10. Cover with a watch glass allow reaction to proceed until no more brown fumes are generated or all the silver is consumed.
  11. If all the silver has been consumed, add more silver in 5-gram increments until no more fumes are generated and there is silver in the bottom of the beaker. (This will ensure all the nitric is used up)
  12. Decant solution into a clean 1,000 mL beaker.
  13. Add 150mL of distilled water to beaker. (Don't be afraid to use extra water here, if your silver nitrate is too concentrated, it forms a shell on the copper wire and stalls the reaction)
  14. Add a coil of copper grounding wire to the beaker by hanging it above the bottom using nylon string, agitate or stir with magnetic stir-bar.
  15. Add 5 drops of concentrated nitric acid to the beaker. (This helps with starting the cementation process)
  16. Allow reaction to proceed until no more silver cements out of solution on a clean piece of copper wire. (Or take a few milliliters of solution in a test tube and add a drop of hydrochloric acid or sodium chloride, a white cloud indicates silver still in solution, note: this test is very sensitive)
  17. Decant copper nitrate solution into a silver stock pot. Place used coil in stock pot
  18. Wash silver cement multiple times with hot water until solution is clear. Add washing water to stock pot.
  19. Dry silver cement in small crock pot
  20. Transfer silver “cement” dust to a melting crucible and melt at 2,000 degrees Fahrenheit
  21. Pour purified silver into graphite bar mold and drop into water basin to make silver anode bars.
  22. Setup a silver cell and generate purified silver crystal. Need to mix electrolyte while crystals form.
  23. Electrolyte: 150 grams of silver dissolved in nitric and diluted to one liter for electrolytic solution
  24. Place anode bars in anode bag/basket, push 3.5v across anode bar and stainless steel cathode (this will be >3.5v on the power supply
  25. Monitor daily for any long crystals(knock these down) and how blue solution gets from dissolved copper.
  26. A drop or two of nitric acid daily assists with keeping silver in solution
  27. Run all anode bars until stainless steel bowl is full of crystal or you run out of anode bars.
  28. Decant used electrolyte, dilute with distilled water and add copper wire coil to cement out remaining silver, re-use cement for next electrolyte solution or add to next batch of sterling processing.
  29. Rinse crystals well in plenty of hot water
  30. Dry, melt and pour bars of four 9's silver using tabletop furnace and graphite mold
  31. Weigh, stamp, and stash away for daughter's college fund.
  32. Clean all the glassware, silver cell, and do waste processing!
You can dissolve some crystals in nitric acid. It should be crystal clear. You can then add a drop of ammonium hydroxide to a test sample and if it turns blue it has copper in it.

Elemental
 
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Elemental said:
I use a silver cell for after chemical refinement to get the silver from ~98-99% pure to four 9's fine silver. Putting sterling silver into a silver cell will quickly foul the electrolyte with copper nitrate.
Click to expand...
But it is still more cost effective than dissolving the feed stock in nitric, cementing, melting to cast anodes, then running in the cell. Sure, sterling will build up the copper level faster than 3N feedstock, but what is the cost for nitric and copper to get the feedstock to 3N?

For lesser material, you can run it as a two step operation. The first cell is a break down cell. Monitor it as it runs. As copper builds up, replace part of the electrolyte to keep it running. Where I live, electricity is cheaper than nitric. Then you can melt the crystal for anodes and run it through a second cell if needed.

Dave
 
Dave,

You're right about it being cheaper to just run a couple of parallel silver cells to get from sterling to fine silver. For me it was more about a hobby that let me do wet chemistry than it is as a side business (all my refined metal is being stashed away for my daughter's college/wedding fund). As a hobby I don't really expect to make money on it, nor invest the time to as efficient as possible (although I certainly do try my best). I'll give the dual-silver cell process a try next spring when I open the lab back up. It'll be something new to try and document. Thanks for pointing it out. I'll also be starting my first attempt at gold refining next spring as well. I'm really looking forward to getting to refine the "real" metals!

As for a bit of math on costs, I spent $230.64 on 10L of conc. nitric acid. To refine 3kg to four 9's fine silver, I've used half of it (5L), so about a $100. (Some of that was used in simple experimentation as well.) Below is my invoice for nitric acid:

Product Name: Nitric Acid, 4 x 2.5L, 67.2% Concentration by Weight,
4 x 2.5L PVC-Coated Bottles
Item#: na10l
Unit Price: $208.02
Quantity: 1
Shipping Method: Fedex Home Delivery S&H

Fedex Home Delivery S&H: $22.62
Grand Total: $230.64

Elemental
 
Elemental said:
Here is the basic recipe that I follow. Although I have a spreadsheet now to calculate distilled water/acid/sterling ratios.

Elemental's Steps for Refining Silver
  1. Melt sterling silver and slowly pour into water basin to make silver corn-flakes. (This step can be skipped, but dissolving the silver takes longer)
  2. Measure out 110 grams of silver corn-flakes and place in a clean 500mL beaker.
  3. Add 150mL of distilled water to beaker.
  4. Heat the beaker on a hot-plate to 80 degrees Celsius
  5. Add 50mL of 70% concentrated nitric acid
  6. Cover with a watch glass allow reaction to proceed until no more brown fumes are generated.
  7. Add 50mL of 70% concentrated nitric acid
  8. Cover with a watch glass allow reaction to proceed until no more brown fumes are generated.
  9. Add 50mL of 70% concentrated nitric acid
  10. Cover with a watch glass allow reaction to proceed until no more brown fumes are generated or all the silver is consumed.
  11. If all the silver has been consumed, add more silver in 5-gram increments until no more fumes are generated and there is silver in the bottom of the beaker. (This will ensure all the nitric is used up)
  12. Decant solution into a clean 1,000 mL beaker.
  13. Add 150mL of distilled water to beaker. (Don't be afraid to use extra water here, if your silver nitrate is too concentrated, it forms a shell on the copper wire and stalls the reaction)
  14. Add a coil of copper grounding wire to the beaker by hanging it above the bottom using nylon string, agitate or stir with magnetic stir-bar.
  15. Add 5 drops of concentrated nitric acid to the beaker. (This helps with starting the cementation process)
  16. Allow reaction to proceed until no more silver cements out of solution on a clean piece of copper wire. (Or take a few milliliters of solution in a test tube and add a drop of hydrochloric acid or sodium chloride, a white cloud indicates silver still in solution, note: this test is very sensitive)
  17. Decant copper nitrate solution into a silver stock pot. Place used coil in stock pot
  18. Wash silver cement multiple times with hot water until solution is clear. Add washing water to stock pot.
  19. Dry silver cement in small crock pot
  20. Transfer silver “cement” dust to a melting crucible and melt at 2,000 degrees Fahrenheit
  21. Pour purified silver into graphite bar mold and drop into water basin to make silver anode bars.
  22. Setup a silver cell and generate purified silver crystal. Need to mix electrolyte while crystals form.
  23. Electrolyte: 150 grams of silver dissolved in nitric and diluted to one liter for electrolytic solution
  24. Place anode bars in anode bag/basket, push 3.5v across anode bar and stainless steel cathode (this will be >3.5v on the power supply
  25. Monitor daily for any long crystals(knock these down) and how blue solution gets from dissolved copper.
  26. A drop or two of nitric acid daily assists with keeping silver in solution
  27. Run all anode bars until stainless steel bowl is full of crystal or you run out of anode bars.
  28. Decant used electrolyte, dilute with distilled water and add copper wire coil to cement out remaining silver, re-use cement for next electrolyte solution or add to next batch of sterling processing.
  29. Rinse crystals well in plenty of hot water
  30. Dry, melt and pour bars of four 9's silver using tabletop furnace and graphite mold
  31. Weigh, stamp, and stash away for daughter's college fund.
  32. Clean all the glassware, silver cell, and do waste processing!
You can dissolve some crystals in nitric acid. It should be crystal clear. You can then add a drop of ammonium hydroxide to a test sample and if it turns blue it has copper in it.

Elemental
Click to expand...
Very nicely written. Good lead for anyone attempting this sequence

In terms of evaluating cost effectiveness... If I purchase nitric here for registered company, it would cost somewhere around 2,5 euro per liter (65%), so i will definitely go for nitric path in the start.
But the idea with two cells in series is appealing :) as long, that i could only dream about steady supply of this cheap nitric :D or better said, any nitric :)
 
I get my nitric from Legend Mining in Reno, there are no shipping/hazard fees if you choose in-store pickup. $167 for a case of 6 2.5L bottles. I just place an order about a month ahead of when I make a trip up there and pick it up while I'm already in the area for other things. I would look into similar mining supply companies in your area.
 
FrugalRefiner said:
But it is still more cost effective than dissolving the feed stock in nitric, cementing, melting to cast anodes, then running in the cell. Sure, sterling will build up the copper level faster than 3N feedstock, but what is the cost for nitric and copper to get the feedstock to 3N?

For lesser material, you can run it as a two step operation. The first cell is a break down cell. Monitor it as it runs. As copper builds up, replace part of the electrolyte to keep it running. Where I live, electricity is cheaper than nitric. Then you can melt the crystal for anodes and run it through a second cell if needed.

Dave
Click to expand...
Great point this really sounds more realistic. Especially considering nitric prices could even soar higher along with shipping and taxes... Nitric adds up fast if you are going through a lot of sterling.
 
voidforged said:
I get my nitric from Legend Mining in Reno, there are no shipping/hazard fees if you choose in-store pickup. $167 for a case of 6 2.5L bottles. I just place an order about a month ahead of when I make a trip up there and pick it up while I'm already in the area for other things. I would look into similar mining supply companies in your area.
Click to expand...
That sounds a lot more reasonable. Local pickup would definitely be the way to go.
 
orvi said:
I think it should be far less. If we talk about dissolving pure silver, idealized reaction would be:

Ag + 2 HNO3 ---> AgNO3 + NO2 + H2O

So 2 moles of nitric required for one mol Ag. One mol Ag is 107,9 g. Two moles of nitric required (68% w/w) are 185,3 g = 123 ml.
Click to expand...

Concerning - "how much acid (nitric) it takes to dissolve a given amount of metal (silver)" - there needs to be some clarification made here

When dissolving metal with acid (nitric in particular) there is NO SUCH THING as "it takes" or "you need" or "required"

Whether trying to calculate it by moles of acid to moles (of a given) metal --- or trying to calculate it by X ml acid per X grams metal (when referenced as - required, it takes or you need) you will almost always if not always be wrong

Why ? --- because those are "rules of thumb" not "absolute laws"

The "actual" amount of acid it takes to dissolve a given amount of metal will depend A LOT on the conditions involved in dissolving the metal

Depending on the conditions it can & will "more likely" ether take more acid or less acid to dissolve your given amount of metal & that can very - more or less - by a lot

Therefore - the advice of how much acid it takes to dissolve a given amount of metal should NEVER be given in terms of - it takes or you need or required --- that will only lead to people "wasting" acid

Therefore - using "rule of thumb" numbers the advice should ALWAYS be that it takes or you need or it requires ABOUT - X amount acid to X amount metal

Example; - the advice - often given - is that "IT TAKES" 1.17 mil 70% nitric plus 1.17 ml distilled water to dissolve 1 gram of silver --- & that just is not true because depending on the conditions in dissolving the metal you will MOST LIKELY end up dissolving all of the metal with left over "free acid" - or not dissolving all the metal & needing to add more acid --- both of which means you are WASTING acid --- so those numbers are a rule of thumb of "about" how much acid it takes - not an absolute law of the acid required

As a rule of thumb it takes ABOUT 1 gallon of 67 - 70% nitric to dissolve ABOUT 8 pounds of silver - BUT - 1 gallon of nitric will only dissolve ABOUT 2 pounds of copper --- so it takes ABOUT 4 times more nitric to dissolve copper then to dissolve silver

Or ABOUT 1 ml 67 - 70% nitric per gram silver - or ABOUT 4 ml nitric per gram copper

If you control the conditions that you dissolve your metal under you can almost always - if not always use "less" (even much less) acid then the numbers I just gave you

So that you do not go wasting acid you will be best served by using about 70% of the above numbers when you first add your acid to the metal you want to dissolve (in other words - with silver - start out with about .7 ml nitric per gram silver) you can always add more nitric - if need be)

I have posted about this "many" times before

here are "some" links that will better explain the "conditions" & if you follow what I have posted about "conditions" you will ultimately end up saving yourself a lot of acid thereby cutting your cost & making more money - read everything I have posted in these threads & as will read any link provided in those post

https://goldrefiningforum.com/threads/dissolving-the-copper-in-sterling-nitric-qty.29286/
https://goldrefiningforum.com/threads/first-attempt-at-silver-refining.29559/page-2#post-310968
Kurt
 
kurtak said:
Concerning - "how much acid (nitric) it takes to dissolve a given amount of metal (silver)" - there needs to be some clarification made here

When dissolving metal with acid (nitric in particular) there is NO SUCH THING as "it takes" or "you need" or "required"

Whether trying to calculate it by moles of acid to moles (of a given) metal --- or trying to calculate it by X ml acid per X grams metal (when referenced as - required, it takes or you need) you will almost always if not always be wrong

Why ? --- because those are "rules of thumb" not "absolute laws"

The "actual" amount of acid it takes to dissolve a given amount of metal will depend A LOT on the conditions involved in dissolving the metal

Depending on the conditions it can & will "more likely" ether take more acid or less acid to dissolve your given amount of metal & that can very - more or less - by a lot

Therefore - the advice of how much acid it takes to dissolve a given amount of metal should NEVER be given in terms of - it takes or you need or required --- that will only lead to people "wasting" acid

Therefore - using "rule of thumb" numbers the advice should ALWAYS be that it takes or you need or it requires ABOUT - X amount acid to X amount metal

Example; - the advice - often given - is that "IT TAKES" 1.17 mil 70% nitric plus 1.17 ml distilled water to dissolve 1 gram of silver --- & that just is not true because depending on the conditions in dissolving the metal you will MOST LIKELY end up dissolving all of the metal with left over "free acid" - or not dissolving all the metal & needing to add more acid --- both of which means you are WASTING acid --- so those numbers are a rule of thumb of "about" how much acid it takes - not an absolute law of the acid required

As a rule of thumb it takes ABOUT 1 gallon of 67 - 70% nitric to dissolve ABOUT 8 pounds of silver - BUT - 1 gallon of nitric will only dissolve ABOUT 2 pounds of copper --- so it takes ABOUT 4 times more nitric to dissolve copper then to dissolve silver

Or ABOUT 1 ml 67 - 70% nitric per gram silver - or ABOUT 4 ml nitric per gram copper

If you control the conditions that you dissolve your metal under you can almost always - if not always use "less" (even much less) acid then the numbers I just gave you

So that you do not go wasting acid you will be best served by using about 70% of the above numbers when you first add your acid to the metal you want to dissolve (in other words - with silver - start out with about .7 ml nitric per gram silver) you can always add more nitric - if need be)

I have posted about this "many" times before

here are "some" links that will better explain the "conditions" & if you follow what I have posted about "conditions" you will ultimately end up saving yourself a lot of acid thereby cutting your cost & making more money - read everything I have posted in these threads & as will read any link provided in those post

https://goldrefiningforum.com/threads/dissolving-the-copper-in-sterling-nitric-qty.29286/
https://goldrefiningforum.com/threads/first-attempt-at-silver-refining.29559/page-2#post-310968
Kurt
Click to expand...
Yes I agree it would never be exact. I guess for this question though I am attempting to come up with a good average for cost analysis. So far, with the cheapest nitric acid I have found being about $200 for 10L, I am looking at about $1 per ounce to refine sterling assuming about 50ml per ozt of sterling. Thats nearly a 5% cut off the margin plus time required so its not that great and then finding a buyer will also be another issue.
 
kurtak said:
Concerning - "how much acid (nitric) it takes to dissolve a given amount of metal (silver)" - there needs to be some clarification made here

When dissolving metal with acid (nitric in particular) there is NO SUCH THING as "it takes" or "you need" or "required"

Whether trying to calculate it by moles of acid to moles (of a given) metal --- or trying to calculate it by X ml acid per X grams metal (when referenced as - required, it takes or you need) you will almost always if not always be wrong

Why ? --- because those are "rules of thumb" not "absolute laws"

The "actual" amount of acid it takes to dissolve a given amount of metal will depend A LOT on the conditions involved in dissolving the metal
Click to expand...
I didn´t meant to post a universal number, maybe it was misunderstood. I wanted to correct the first assumption:
ssharktu17 said:
Ok maybe I am missing something but most searches are saying 150ml nitric to dissolve one ounce of sterling? Even 10liters at $150 ($200 after taxes +shipping) is almost $3 per ounce to dissolve??
Click to expand...
The issue from start was financial analysis, if that expensive nitric (50 USD/liter) could be used to make some profit with refining silver. I was pointing out many times, that the reaction and numbers are idealized to the corresponding equation to give estimated consumption of nitric per ozt. sterling, as there are other options of refining if the nitric cost will be to high. I just wanted to show that it is easy to estimate your consumption of acid, to know roughly how much you will need for your batch.
 
orvi said:
I didn´t meant to post a universal number, maybe it was misunderstood. I wanted to correct the first assumption:

The issue from start was financial analysis, if that expensive nitric (50 USD/liter) could be used to make some profit with refining silver. I was pointing out many times, that the reaction and numbers are idealized to the corresponding equation to give estimated consumption of nitric per ozt. sterling, as there are other options of refining if the nitric cost will be to high. I just wanted to show that it is easy to estimate your consumption of acid, to know roughly how much you will need for your batch.
Click to expand...
I still have trouble justifying refining sterling. It seems like the only reason to do it would be if you are actually starting a full retail business to sell bars at a premium to customers. Even still I don't know how these guys make a profit. Bars usually only go about 10% over spot at best. So if you can get 90% melt value from a refiner then that is going to be a lot of work for just an extra 10% or less of profit after expenses. Especially considering some sterling may even get melt value. Seems like the only reason to refine it would be to make small high premium rounds. Maybe I am missing something.
 
orvi said:
lucky you :) 10 liters for 150... very good price. i once thought about getting license, but this would be dive into the pile of s*it here.
for liter, it is like 2,50+-, but tech grade 50% stuff in bulk (1000 L) is going below 60 cents.
my whole refining is impaired by this restriction. practically speaking, only HCl is sold restriction-free for public here. luckily, i have access to some more "exotic" chemicals, mostly old stuff... to substitute the nitric. hence my experience with making it :D that was like 5 years ago, i have done it the last time.

Edit: bad maths, i missed one zero :/ anyway, if i could get it for 15/liter, i would go all in
Click to expand...

ssharktu17 said:
I still have trouble justifying refining sterling. It seems like the only reason to do it would be if you are actually starting a full retail business to sell bars at a premium to customers. Even still I don't know how these guys make a profit. Bars usually only go about 10% over spot at best. So if you can get 90% melt value from a refiner then that is going to be a lot of work for just an extra 10% or less of profit after expenses. Especially considering some sterling may even get melt value. Seems like the only reason to refine it would be to make small high premium rounds. Maybe I am missing something.
Click to expand...
For me sterling silver refining is a primer for gold refining. Gold refining is a big investment. The small amount of gold jewelry scrap I’ve been able to find is expensive for someone looking to make this a hobby. Silver also allows me to practice my wet chemistry skills which were pretty rusty.
 
Elemental said:
For me sterling silver refining is a primer for gold refining. Gold refining is a big investment. The small amount of gold jewelry scrap I’ve been able to find is expensive for someone looking to make this a hobby. Silver also allows me to practice my wet chemistry skills which were pretty rusty.
Click to expand...
that makes sense good practice. I don’t deal with gold at all just sterling. If I find some gold I usually just sell it for melt pretty quickly on marketplace. I find a lot more sterling though.
 

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