18k White gold

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jeweler1

jeweler1

Well-known member
Joined
Sep 12, 2011
Messages
51
Location
Ohio
My question is based on this quote (from this forum)
“AR Recipe 2= Poor Man’s AR = 8 oz Sodium Nitrate (added in small increments), (aka Subzero), 480 ml water, 960 ml Muriatic Acid plus heat. Used to dissolve high karat gold, dissolves Platinum when hot, Excess nitric must be evaporated off neutralized with Urea to pH 1 +/- 0.4, than drop gold with SMB. The above mentioned recipe makes enough AR to dissolve 160 gm Pins of 32 oz of ceramic cups.”
My first refining will be of 29 gm of powdered 18k white gold (all nickel no pt or pl.) is there a formula that can tell me how much Poor Mans AR will be needed to dissolve this will the above formula work? (Without creating an excess of Nitric acid) and how hot should it be? Boiling? I want to use enough to dissolve it all.
Ph 1 is very acidic? 7 being water.?
 
the best way to use AR, whatever nitrate you use will work the same way. add enough hcl (muriatic acid) to cover your material and then double the volume with water. bring this to a slow boil. start adding your nitrate slowly (if you are using nitric acid, 10 ml's at a time) dry nitrate (sodium or potassium) should be add in 1-2 gram increments. nitric acid will react immediately, dry nitrate will react as soon as it dissolves. be sure to cover your beaker with a watch glass. red NO2 gas will evolve, use this as an indicator when to add more nitrate. as long as NO2 gas is being evolved, metal is being dissolved. when the NO2 can no longer be seen,add another increment. keep an eye on the material. stop additions when there is very little metal left undissolved. continue to boil until no NO2 gas is observed. turn off the heat and allow the solution to cool completely and observe, you are looking for the formation of silver chloride. it will precipitate as the solution cools if silver was present in the material.

if you follow this process, there should be no excess free nitric to rid in your solution. filter well after it cools completely. i dilute my solution by adding ice. this serves two purposes, it chills the solution and precipitates any additional silver chloride that may be present. wait another hour to see if any precipitates and filter well. proceed to precipitating the gold.

do any processes in a fume hood or outside with a good breeze. do not breathe the fumes. respirators will not work on NO2 fumes.
 
Geo, look at your post again. You are breaking on of the cardinal rules when using acid, NEVER ADD WATER TO ACID. You should always add acid to water.
 
yep. typing a long response like that throws me off. i should have worded it different.what it should have said was.

measure out the hcl needed to cover the material and double the volume with water while adding a warning of adding acid to water and never water to acid.

good catch Westerngs. thank you for pointing that out and getting me straight.
 
Geo,

I knew you would not do what you wrote you did. I have read many of your posts and can tell you know what you are doing.
 
Sounds like very good advice I did know about the acid to water but thanks anyway and I do have a fume hood
"you can be careful as many times as you like but only stupid once"
This will be my 1st refinement and I want to get it right . Your advice was just what I needed
I'll let you know the results
 
So far so good your advice about adding Sodium Nitrate 1-2 grams at a time was very useful I boiled the mix and added it until the foaming stopped and no more red gas. My next question is how do I tell if Nitric acid is present? Or should I just use Urea until it stops foaming to be sure? Before I use SMB to precipitate it?
 
if you did it correctly, there should be none to very little free nitric in solution. what little free nitric is there can be overcome by diluting with double the volume of water and adding SMB. you will know for sure when you add the SMB (i add mine dry for this purpose) if there is free nitric acid, the SMB will fizz when added and NO2 fumes will be emitted. if there is little to no fizz, then you did the process correctly and theres nothing left to do but precipitate the gold.

as a side note. there can be a couple of reasons the reaction stopped. one being the reaction ran out of nitrate and the other is it ran out of hcl. its always a good idea to add a small volume of hcl to the solution before the reaction is complete. its better to err on the hcl than the nitrate.
 
Today I filtered it through a coffee filter .The solution was army green in color I tested it with a ph test strip and it tested 0 than I tested it with stanius chloride and it was strongly purple . I followed your instructions precisly should I now add some hcl to be sure?
I will try some SMB later and observe the results. if it does fiss should I add urea than?
"Knowledge might be King and knowing how to use it is surly Queen"
 
no need to add hcl at this stage. additional hcl can and should be added near the end of the dissolution. Harold recommends you add a button of gold and heat the solution. if free nitric is in the solution, it will react to the gold and start dissolving it. this reaction will use up any small amount of nitric available.

if you are ready to precipitate the gold, add a small amount of SMB and observe any reaction.even a slightly energetic reaction can be overcome by adding SMB in small increments of a gram or more. add a gram and watch, if it reacts, stir it in well and wait an hour. add another gram and watch for the reaction. repeat this until there is no reaction and proceed with the gold drop.

when you add a small amount of SMB and you get a reaction, it means there is free nitric. still a small amount of gold will precipitate. as this gold precipitates, it will be dissolved back into the solution using up the free nitric as it does until all the free nitric is used up.
 
Success! Sucess1 after I filtered it (black powder filtered out I think this was Nickel). I added 1 gram of SMB with no reaction accept a fine brown streak in the solution. I waited an hour and saw a fine residue (brown) on the bottom seeing that none had redissolved I added more SMB until there was no more brown precipitant. It now began to foam a little and gave off strong Ammonia smell (Glad I built a fume hood) I could spoon the dark brown powder out (Gold) It was heavy and looked like instant coffee. Next step washing, drying, and melting
Thanks again for all your detailed help.
“Happy, Happy, Joy, Joy”

:lol:
 
i doubt that any undissolved powder is nickel. Rh perhaps, Pt dissolves in AR at a hard boil. more than likely, it is undissolved gold from an incomplete dissolution. do not toss the filters. keep all filters. i keep my filters in a ziplok bag slightly moist. nitric soaked dry paper can spontaneously combust.

i dont think you smelled ammonia. it was more than likely SO2 gas emitted from the solution due to the SMB dissolving.

congratulations on your success.
 
Geo said:
the best way to use AR, whatever nitrate you use will work the same way. add enough hcl (muriatic acid) to cover your material and then double the volume with water. bring this to a slow boil. start adding your nitrate slowly (if you are using nitric acid, 10 ml's at a time) dry nitrate (sodium or potassium) should be add in 1-2 gram increments. nitric acid will react immediately, dry nitrate will react as soon as it dissolves. be sure to cover your beaker with a watch glass. red NO2 gas will evolve, use this as an indicator when to add more nitrate. as long as NO2 gas is being evolved, metal is being dissolved. when the NO2 can no longer be seen,add another increment. keep an eye on the material. stop additions when there is very little metal left undissolved. continue to boil until no NO2 gas is observed. turn off the heat and allow the solution to cool completely and observe, you are looking for the formation of silver chloride. it will precipitate as the solution cools if silver was present in the material.

if you follow this process, there should be no excess free nitric to rid in your solution. filter well after it cools completely. i dilute my solution by adding ice. this serves two purposes, it chills the solution and precipitates any additional silver chloride that may be present. wait another hour to see if any precipitates and filter well. proceed to precipitating the gold.

do any processes in a fume hood or outside with a good breeze. do not breathe the fumes. respirators will not work on NO2 fumes.
Click to expand...

Are you using 31% HCL and 67% HNO3 here?
 
when using nitric acid to make AR, you should use concentrated acid. the water is added to help diminish and retain the SO2 from being emitted.add the acids concentrated. add the water first and add the hcl needed for the reaction and add nitric in small increments until the reaction is complete. stop additions of nitric when ALL metal is dissolved.
 

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