Oneal,
Below is one I posted, I really like it, one of my favorite’s actually I tried to explain this process I came up with, one on one of the first posts I made coming to the forum, I could not type then and was not very good at computers or the English and grammar, running all the sentences together (I may have gotten a little better now but sure you guys still have a hard time with my skills in this matter), I was a newbie, and had been lurking for a while before deciding to post, so I had an admiration of Harold, GSP, (Chris), Irons, Lou, and others, well I made my this first post trying to share my process, Harold chimed in saying he could not read a word I said, (man that hurt, I almost said to heck with this forum and quit then, but Ragbone chimed in, and calmed down my hurt pride, and I stuck with the forum trying to make my posts where Harold could read them), (Harold has taught me much not only in gold refining but in other walks of life, funny how a man who you have never seen, but you look up to can make such a difference in your life, never met Him but will always consider Him a friend and mentor
I also make nitric the cold method Laser Steve’s recipe, it is the best I have found (I have studied nitric intensely), this solution, works well for everything but silver (but you can distill it and then it is good for silver. So this is the method I suggest you begin with, there is also much information of this process here on the forum.
I have also made fuming nitric, but there is no need to make that or use that.
So 68% is the strongest you need (used in aqua regia), and more dilute to remove base metals and silver.
Always distill homemade nitric for silver.
I have made many posts on the properties of nitric acid, how to concentrate it, and its azeotropic nature, I will not go into that again now,
There are other processes to make nitric, I will not mention now, as it would just clutter this page.
I can process gold plated pins and make nitric acid at the same time here is my favorite process “Kill two birds one rock”, the principles here have many uses not only with the process stated here, and can be adapted to other processes.
You can use lab glass, distilling rig, but I still use my old pickle jar.
Process for pins, nitric acid and copper sulfate
Kill two birds one stone
A few principles:
You need sulfuric acid with nitrate (salts) to create nitric acid,
Gold will not dissolve in nitric acid alone,
Copper will dissolve in nitric acid evolving NO2 gas.
NO2 gas bubbled into water can form nitric acid.
NO2 + H2O --> HNO3
NO gas also evolves; oxygen will convert this to NO2,
NO + O2 --> NO2
So: if we add a little H2O2 to this we have oxygen and water, we can convert NO gas to HNO3,
NO + H2O2 --> HNO3
Gold will not dissolve in copper nitrate or copper sulfate.
Nitric acid will evaporate from a solution at a much lower temperature than a sulfate will.
2 NaNO3 + H2SO4 --> Na2SO4 + 2HNO3
Nitrate fertilizer + sulfuric acid àsodium sulfate + nitric acid.
In our case we are using copper to help.
Copper dissolving in nitric acid evolves NO2 and NO fumes.
Cu + 2 HNO3 --> CuNO3 + 2NO2(g) + 2 H2O
When we distill this copper nitrate we remove the Nitrate and leave the copper sulfate behind, diluting this to retrieve our un-dissolved gold.
Cu(NO3)2 + H2SO4 --> CuSO4 + 2HNO3
Copper sulfate is water-soluble.
(Copper sulfate solution we make here is soluble while hot, but will crystallize out as bright blue crystals if allowed to cool, (copper sulfate crystals once formed are harder to dissolve) than if we keep them hot while diluting the solution not allowing them to crystallize).
This is my method for pins (which can be adapted to distill copper nitrate solution to make nitric acid) or adapted for use with other chemicals and processes.
(This process can be adapted to other recovery or refining methods to kill two birds with one stone, like recovering nitric or aqua regia while dissolving karate gold)
A distilling unit rig (I have a nice lab distilling unit), but I like my homemade kit, and use it for this process, my unit has survived many distillations, but as with any distilling glass precautions must be observed,
Some supplies I use:
(My Pickle jar distilling kit)
Large pot with handles
Sand
Canning gallon pickle jar
A lid for gallon jar --made from 1/2" thick Teflon,(or the plastic wood they make decks out of HDPE I think) turned on a lath beveled edge to tightly fit jar, small lip on top edge, a hole in center for tight fit of 1/4" hose.
8' 1/4" Teflon hose
Long neck bottle
(For this bottle either loose fitting Teflon cork with hole or just use tape)
Gallon bucket of ice water
Double burner electric hot plate
(Ground fault protected electrical outlet)
Fiberglass catch tray for burner to sit on to catch any spill
Pyrex coffee pot
Some wire, plumbers Teflon tape, cloth tape, electricians black tape
New battery sulfuric acid 10 cups, (we will boil down to 6 cups)
Cup of sodium or Potassium nitrate fertilizer
One pound of (copper) gold plated pins no solder (cut to expose copper to acid)
(Teflon will withstand temperature and fumes of these acids)
(A nearby box of baking soda and water for safety)
Required:
Understand the dangers of these acids, and precautions to take, understand the danger of the nitrous gases formed, and precautions to take, understand the principles of distilling and precautions needed, understand glass cannot withstand thermal shock (rapid temperature change).
Never cool or lower temperature to boiling reaction vessel without removing line to condenser,(which can cause suck back of cold solution into hot boiling flask breaking it through thermal shock),always remove tube before lowering heat on boiling flask,
Work outdoor using breeze or with fume hood, take safety precautions.
Double hotplate sits on fiberglass catch tray; ground fault electrical source is used outdoors
10 cups of sulfuric battery acid boiled down to 6 cups in the Pyrex coffee pot on one burner boil down to 6 cups and cool. To boil off some water in the acid, it will still contain some water (We will use this cool sulfuric acid later),
(We could also pour concentrated sulfuric acid drain cleaner into water to dilute it).
The large pot, pour a couple of inches of sand in bottom of it spread flat, the gallon canning pickle jar is sits on this sand centered in the large pot and sand poured in between pots metal and outside of pickle jar, to make a boiling reactor with a sand bath. This will help to protect our glass from thermal shock, (sand bath around pickle jar), allowing heat to change slowly, and can act as catch basin if we make a mistake. The 1/4" Teflon hose fits tightly into Teflon lid for our gallon pickle jar boiling reaction vessel, we will be collecting NOx gas from this vessel, so hose just in through the lid just a little ways, to capture gasses formed in reaction vessel.
(Later we will tape on this lid, and tie it down)
(Get tape and wire ready and handy within reach, we will need it as soon as acid is added later)
Get ice water in gallon bucket (plastic ok) this is for cooling our gases and condensing them, our collection bottle will sit in this bucket,
Put small amount of water in the long neck bottle (collection bottle for condensed nitric acid) for NOx gas to bubble through water, (I add a little H2O2 peroxide to help conversion, it is not necessary), put one end of the Teflon 1/4" hose into this collection bottle all the way down into bottom of bottle so gases bubble through water and hydrogen peroxide inside, (through a loose fitting Teflon cork or else just tape hose to top of bottle, air, and some gas will need to escape from this bottle, and we do not want to prevent this with a tight fitting lid), this long neck bottle needs to sit down in iced water of bucket to condense gas to liquid, and we need to hold it down in ice water (it wants to float till it fills), so we tie in down into ice water bucket, this is our condenser receiver for the NOx fume's which will bubble into water in this longneck bottle and convert to nitric acid, a few loops of this hose is under ice water to help condense fumes also.
Set large pot sand bath with our fancy pickle jar boiler reaction vessel on cold electric hotplate, put one pound solder free (copper) gold plated pins, (cut to expose copper to acid I cut mine small for more exposure), in reaction vessel, add one cup of sodium nitrate fertilizer, (with lid and tape handy ready we will need to put on lid to contain brown NOx fumes in next step), pour in cooled 6 cups sulfuric acid on these, quickly put on Teflon fitting on lid and taping on the with Teflon plumbers tape first, then bandage cloth tape, then black electrical tape sealing this lid well, the insulated solid copper tie wire is tied to one handle of the pot over top of lid on jar and tied to other pot handle, this will hold down the lid when pressure builds,
As soon as you pour the sulfuric acid on the nitrate fertilizer and copper, red brown nitrous gas NOx begins to form, so getting lid on quickly and taping to seal is needed, we will need no heat yet, as it creates its own heat from chemical reaction, turning burner on warm will start to heat pot and sand, with time, the heat will saturate sand and starts to warm the jar. When reaction slows (bubbling in receiver slows) and pot is warm raise heat a little, (little bit at a time) giving time for heat to reach and react chemicals as red fume slow, or gas bubble slow in receiver, we want a steady few bubbles, not too fast we only want the gas to go to the condenser and receiver. (There is a point to where nitric will concentrate to azeotrope in the boiling flask and reaction begins to get more vigorous with red fume’s of NOx gas), keeping a steady stream of bubble into our receiver is our goal, not liquid the blue liquids from our boiling flask).
Caution we do not want to change temperature on glass fast, this thermally shocks glass and will crack or break it, always keep this in mind.
Do not lower the temperature of the boiling vessel, with the hose in the condenser receiver, always remove this hose from the receiver first allowing it to suck air, (this higher temperature in the boiling vessel creates a pressure, and if we lower the temperature on this boiling vessel, it will go into a vacuum, this will suck the cooler condensed liquid back into this hot boiling flask, thus causing thermal shock and cracking our jar, by removing this hose first it just suck’s back air, and not liquid, as the pressure lowers in this boiler reaction vessel.
(I preheat a coffee pot of water, just below boil for procedure below, starting the water heating before hand)
We do not want to evaporate this now forming copper sulfate to a dry salt, we just want to drive out the formed nitric acid, so we evaporate to thick syrup, (I have noticed a color change from blue-green to blue-blue as the nitrates are driven out of the copper sulfate),
After we have evaporated down to syrup.
NOTE:
We want to remove hose from the condenser receiver, before lowering temperature.
(See caution on suck-back of these cooler liquids when lowering temperature of reaction vessel, thermal shock),
We can let cool before diluting this copper sulfate syrup, but this will form salts and it takes more water to dilute, (that may be best for you as this step if not done properly can thermally shock your boiling vessel), I use the water we heated above (on second burner in coffee pot, getting this water to about the same temperature of this syrup, and very slowly adding this boiling hot water to the syrup to dilute it, starting with just drops at a time, not pouring in all at once, this dissolves the blue copper sulfate syrup and leaves gold shells and powder from pins.
Allow this dilute copper sulfate liquid to settle the gold, and then decant liquid from gold and filter solution.
These gold foils will need further treatment to refine to pure gold.
This copper sulfate can be evaporated to nice blue crystals of copper sulfate for other chemical reactions, or for an electrolytic cell or other uses, wall mart sells them at a high price to keep roots from growing in sewer lines.
This nitric acid tested for strength, and evaporated to 68% concentration azeotrope if necessary, cool, stored in amber nitric bottle with proper lid put out of light (light breaks down nitric). Store in safe place for later use in recovery or refining
Distilling copper nitrate, (adding copper or gold plated copper can assist creating NOx fumes in boil, which also is a way I get gold plating from Pins. killing two birds one stone) would get nitric back from this copper chloride solution, bubble NOx gas into water, for dilute nitric, which can then evaporate water from dilute nitric until 68%HNO3 azeotrope, (many acids form azeotropes), so if just evaporating a dilute nitric solution, below the boiling point of the acid (for the concentration that the acid is at the time in solution), would boil off water (or other volatile components if in solution), making the acid more concentrated in solution, up to the azeotrope of the acid, which for nitric is about 68%, further boiling would only boil off the 68% solution till dry, meaning it cannot be further concentrated by this method, by using the boiling point information a person can have a good idea if they are boiling off acid or just water, the concentration can be tested with specific gravity, or judged by how it attacks metals.
(100% H2O) boils @100 degC density 1.00.
20% HNO3 density 1.115- boiling point 103 degC.
30% HNO3 density1.180 boiling point 107 degC.
50% HNO3 density 1.310 boiling point 116 degC.
70% HNO3 density 1.413 boiling point 121.5 degC.
(Pure HNO3 boiling point is about 83 degC, so you can see the boiling point goes up as the nitric is less concentrated, till about 68% azeptrope (nitric acid’s highest boiling point about 120 degC), then as we get more dilute towards just water the boiling point falls toward the boiling point of water 100 degC).
As you can see the boiling points change with how concentrated the acid is. Keeping below the boiling point most all of your acid stays in solution, and mostly water vapors off, above the boiling point acid leaves solution in vapors with the water.
Other acids and have reaction similar to this. For more information you can study the azeotrope of acid, boiling points, acid concentrating, I have also posted this information on forum in other posts.
{Basically we made nitric acid with nitrate fertilizer and sulfuric acid, nitric acid distilled off in condenser bottle, the copper helping to drive the reaction, dissolved copper from the gold making copper nitrate in solution in boiling vessel, and since we had a slight excess of sulfuric when we distilled out the nitric fumes (making nitric acid ) we left sulfuric acid in boiling flask which forms copper sulfate solution, and gold foils, which we will dilute the copper sulfate with boiling hot water before allowing to cool so we can seperate gold foils from copper sulfate solution}.
I have added some points to this post today; here was the one posted and some questions answered about it,
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=38&t=6199&hilit=kill+two+birds+one+rock
Read and understand dangers involved before attempting, this method it is safe I have done it many times, but precautions must be taken, and dangers must be taken into account.
My hope is this is readable and understandable, and someone will gain information or it will spark ideas in others.
Butcher
Below is one I posted, I really like it, one of my favorite’s actually I tried to explain this process I came up with, one on one of the first posts I made coming to the forum, I could not type then and was not very good at computers or the English and grammar, running all the sentences together (I may have gotten a little better now but sure you guys still have a hard time with my skills in this matter), I was a newbie, and had been lurking for a while before deciding to post, so I had an admiration of Harold, GSP, (Chris), Irons, Lou, and others, well I made my this first post trying to share my process, Harold chimed in saying he could not read a word I said, (man that hurt, I almost said to heck with this forum and quit then, but Ragbone chimed in, and calmed down my hurt pride, and I stuck with the forum trying to make my posts where Harold could read them), (Harold has taught me much not only in gold refining but in other walks of life, funny how a man who you have never seen, but you look up to can make such a difference in your life, never met Him but will always consider Him a friend and mentor
I also make nitric the cold method Laser Steve’s recipe, it is the best I have found (I have studied nitric intensely), this solution, works well for everything but silver (but you can distill it and then it is good for silver. So this is the method I suggest you begin with, there is also much information of this process here on the forum.
I have also made fuming nitric, but there is no need to make that or use that.
So 68% is the strongest you need (used in aqua regia), and more dilute to remove base metals and silver.
Always distill homemade nitric for silver.
I have made many posts on the properties of nitric acid, how to concentrate it, and its azeotropic nature, I will not go into that again now,
There are other processes to make nitric, I will not mention now, as it would just clutter this page.
I can process gold plated pins and make nitric acid at the same time here is my favorite process “Kill two birds one rock”, the principles here have many uses not only with the process stated here, and can be adapted to other processes.
You can use lab glass, distilling rig, but I still use my old pickle jar.
Process for pins, nitric acid and copper sulfate
Kill two birds one stone
A few principles:
You need sulfuric acid with nitrate (salts) to create nitric acid,
Gold will not dissolve in nitric acid alone,
Copper will dissolve in nitric acid evolving NO2 gas.
NO2 gas bubbled into water can form nitric acid.
NO2 + H2O --> HNO3
NO gas also evolves; oxygen will convert this to NO2,
NO + O2 --> NO2
So: if we add a little H2O2 to this we have oxygen and water, we can convert NO gas to HNO3,
NO + H2O2 --> HNO3
Gold will not dissolve in copper nitrate or copper sulfate.
Nitric acid will evaporate from a solution at a much lower temperature than a sulfate will.
2 NaNO3 + H2SO4 --> Na2SO4 + 2HNO3
Nitrate fertilizer + sulfuric acid àsodium sulfate + nitric acid.
In our case we are using copper to help.
Copper dissolving in nitric acid evolves NO2 and NO fumes.
Cu + 2 HNO3 --> CuNO3 + 2NO2(g) + 2 H2O
When we distill this copper nitrate we remove the Nitrate and leave the copper sulfate behind, diluting this to retrieve our un-dissolved gold.
Cu(NO3)2 + H2SO4 --> CuSO4 + 2HNO3
Copper sulfate is water-soluble.
(Copper sulfate solution we make here is soluble while hot, but will crystallize out as bright blue crystals if allowed to cool, (copper sulfate crystals once formed are harder to dissolve) than if we keep them hot while diluting the solution not allowing them to crystallize).
This is my method for pins (which can be adapted to distill copper nitrate solution to make nitric acid) or adapted for use with other chemicals and processes.
(This process can be adapted to other recovery or refining methods to kill two birds with one stone, like recovering nitric or aqua regia while dissolving karate gold)
A distilling unit rig (I have a nice lab distilling unit), but I like my homemade kit, and use it for this process, my unit has survived many distillations, but as with any distilling glass precautions must be observed,
Some supplies I use:
(My Pickle jar distilling kit)
Large pot with handles
Sand
Canning gallon pickle jar
A lid for gallon jar --made from 1/2" thick Teflon,(or the plastic wood they make decks out of HDPE I think) turned on a lath beveled edge to tightly fit jar, small lip on top edge, a hole in center for tight fit of 1/4" hose.
8' 1/4" Teflon hose
Long neck bottle
(For this bottle either loose fitting Teflon cork with hole or just use tape)
Gallon bucket of ice water
Double burner electric hot plate
(Ground fault protected electrical outlet)
Fiberglass catch tray for burner to sit on to catch any spill
Pyrex coffee pot
Some wire, plumbers Teflon tape, cloth tape, electricians black tape
New battery sulfuric acid 10 cups, (we will boil down to 6 cups)
Cup of sodium or Potassium nitrate fertilizer
One pound of (copper) gold plated pins no solder (cut to expose copper to acid)
(Teflon will withstand temperature and fumes of these acids)
(A nearby box of baking soda and water for safety)
Required:
Understand the dangers of these acids, and precautions to take, understand the danger of the nitrous gases formed, and precautions to take, understand the principles of distilling and precautions needed, understand glass cannot withstand thermal shock (rapid temperature change).
Never cool or lower temperature to boiling reaction vessel without removing line to condenser,(which can cause suck back of cold solution into hot boiling flask breaking it through thermal shock),always remove tube before lowering heat on boiling flask,
Work outdoor using breeze or with fume hood, take safety precautions.
Double hotplate sits on fiberglass catch tray; ground fault electrical source is used outdoors
10 cups of sulfuric battery acid boiled down to 6 cups in the Pyrex coffee pot on one burner boil down to 6 cups and cool. To boil off some water in the acid, it will still contain some water (We will use this cool sulfuric acid later),
(We could also pour concentrated sulfuric acid drain cleaner into water to dilute it).
The large pot, pour a couple of inches of sand in bottom of it spread flat, the gallon canning pickle jar is sits on this sand centered in the large pot and sand poured in between pots metal and outside of pickle jar, to make a boiling reactor with a sand bath. This will help to protect our glass from thermal shock, (sand bath around pickle jar), allowing heat to change slowly, and can act as catch basin if we make a mistake. The 1/4" Teflon hose fits tightly into Teflon lid for our gallon pickle jar boiling reaction vessel, we will be collecting NOx gas from this vessel, so hose just in through the lid just a little ways, to capture gasses formed in reaction vessel.
(Later we will tape on this lid, and tie it down)
(Get tape and wire ready and handy within reach, we will need it as soon as acid is added later)
Get ice water in gallon bucket (plastic ok) this is for cooling our gases and condensing them, our collection bottle will sit in this bucket,
Put small amount of water in the long neck bottle (collection bottle for condensed nitric acid) for NOx gas to bubble through water, (I add a little H2O2 peroxide to help conversion, it is not necessary), put one end of the Teflon 1/4" hose into this collection bottle all the way down into bottom of bottle so gases bubble through water and hydrogen peroxide inside, (through a loose fitting Teflon cork or else just tape hose to top of bottle, air, and some gas will need to escape from this bottle, and we do not want to prevent this with a tight fitting lid), this long neck bottle needs to sit down in iced water of bucket to condense gas to liquid, and we need to hold it down in ice water (it wants to float till it fills), so we tie in down into ice water bucket, this is our condenser receiver for the NOx fume's which will bubble into water in this longneck bottle and convert to nitric acid, a few loops of this hose is under ice water to help condense fumes also.
Set large pot sand bath with our fancy pickle jar boiler reaction vessel on cold electric hotplate, put one pound solder free (copper) gold plated pins, (cut to expose copper to acid I cut mine small for more exposure), in reaction vessel, add one cup of sodium nitrate fertilizer, (with lid and tape handy ready we will need to put on lid to contain brown NOx fumes in next step), pour in cooled 6 cups sulfuric acid on these, quickly put on Teflon fitting on lid and taping on the with Teflon plumbers tape first, then bandage cloth tape, then black electrical tape sealing this lid well, the insulated solid copper tie wire is tied to one handle of the pot over top of lid on jar and tied to other pot handle, this will hold down the lid when pressure builds,
As soon as you pour the sulfuric acid on the nitrate fertilizer and copper, red brown nitrous gas NOx begins to form, so getting lid on quickly and taping to seal is needed, we will need no heat yet, as it creates its own heat from chemical reaction, turning burner on warm will start to heat pot and sand, with time, the heat will saturate sand and starts to warm the jar. When reaction slows (bubbling in receiver slows) and pot is warm raise heat a little, (little bit at a time) giving time for heat to reach and react chemicals as red fume slow, or gas bubble slow in receiver, we want a steady few bubbles, not too fast we only want the gas to go to the condenser and receiver. (There is a point to where nitric will concentrate to azeotrope in the boiling flask and reaction begins to get more vigorous with red fume’s of NOx gas), keeping a steady stream of bubble into our receiver is our goal, not liquid the blue liquids from our boiling flask).
Caution we do not want to change temperature on glass fast, this thermally shocks glass and will crack or break it, always keep this in mind.
Do not lower the temperature of the boiling vessel, with the hose in the condenser receiver, always remove this hose from the receiver first allowing it to suck air, (this higher temperature in the boiling vessel creates a pressure, and if we lower the temperature on this boiling vessel, it will go into a vacuum, this will suck the cooler condensed liquid back into this hot boiling flask, thus causing thermal shock and cracking our jar, by removing this hose first it just suck’s back air, and not liquid, as the pressure lowers in this boiler reaction vessel.
(I preheat a coffee pot of water, just below boil for procedure below, starting the water heating before hand)
We do not want to evaporate this now forming copper sulfate to a dry salt, we just want to drive out the formed nitric acid, so we evaporate to thick syrup, (I have noticed a color change from blue-green to blue-blue as the nitrates are driven out of the copper sulfate),
After we have evaporated down to syrup.
NOTE:
We want to remove hose from the condenser receiver, before lowering temperature.
(See caution on suck-back of these cooler liquids when lowering temperature of reaction vessel, thermal shock),
We can let cool before diluting this copper sulfate syrup, but this will form salts and it takes more water to dilute, (that may be best for you as this step if not done properly can thermally shock your boiling vessel), I use the water we heated above (on second burner in coffee pot, getting this water to about the same temperature of this syrup, and very slowly adding this boiling hot water to the syrup to dilute it, starting with just drops at a time, not pouring in all at once, this dissolves the blue copper sulfate syrup and leaves gold shells and powder from pins.
Allow this dilute copper sulfate liquid to settle the gold, and then decant liquid from gold and filter solution.
These gold foils will need further treatment to refine to pure gold.
This copper sulfate can be evaporated to nice blue crystals of copper sulfate for other chemical reactions, or for an electrolytic cell or other uses, wall mart sells them at a high price to keep roots from growing in sewer lines.
This nitric acid tested for strength, and evaporated to 68% concentration azeotrope if necessary, cool, stored in amber nitric bottle with proper lid put out of light (light breaks down nitric). Store in safe place for later use in recovery or refining
Distilling copper nitrate, (adding copper or gold plated copper can assist creating NOx fumes in boil, which also is a way I get gold plating from Pins. killing two birds one stone) would get nitric back from this copper chloride solution, bubble NOx gas into water, for dilute nitric, which can then evaporate water from dilute nitric until 68%HNO3 azeotrope, (many acids form azeotropes), so if just evaporating a dilute nitric solution, below the boiling point of the acid (for the concentration that the acid is at the time in solution), would boil off water (or other volatile components if in solution), making the acid more concentrated in solution, up to the azeotrope of the acid, which for nitric is about 68%, further boiling would only boil off the 68% solution till dry, meaning it cannot be further concentrated by this method, by using the boiling point information a person can have a good idea if they are boiling off acid or just water, the concentration can be tested with specific gravity, or judged by how it attacks metals.
(100% H2O) boils @100 degC density 1.00.
20% HNO3 density 1.115- boiling point 103 degC.
30% HNO3 density1.180 boiling point 107 degC.
50% HNO3 density 1.310 boiling point 116 degC.
70% HNO3 density 1.413 boiling point 121.5 degC.
(Pure HNO3 boiling point is about 83 degC, so you can see the boiling point goes up as the nitric is less concentrated, till about 68% azeptrope (nitric acid’s highest boiling point about 120 degC), then as we get more dilute towards just water the boiling point falls toward the boiling point of water 100 degC).
As you can see the boiling points change with how concentrated the acid is. Keeping below the boiling point most all of your acid stays in solution, and mostly water vapors off, above the boiling point acid leaves solution in vapors with the water.
Other acids and have reaction similar to this. For more information you can study the azeotrope of acid, boiling points, acid concentrating, I have also posted this information on forum in other posts.
{Basically we made nitric acid with nitrate fertilizer and sulfuric acid, nitric acid distilled off in condenser bottle, the copper helping to drive the reaction, dissolved copper from the gold making copper nitrate in solution in boiling vessel, and since we had a slight excess of sulfuric when we distilled out the nitric fumes (making nitric acid ) we left sulfuric acid in boiling flask which forms copper sulfate solution, and gold foils, which we will dilute the copper sulfate with boiling hot water before allowing to cool so we can seperate gold foils from copper sulfate solution}.
I have added some points to this post today; here was the one posted and some questions answered about it,
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=38&t=6199&hilit=kill+two+birds+one+rock
Read and understand dangers involved before attempting, this method it is safe I have done it many times, but precautions must be taken, and dangers must be taken into account.
My hope is this is readable and understandable, and someone will gain information or it will spark ideas in others.
Butcher
