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Borax, Boric Acid Procedure ?

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Nitric

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Post March 22nd, 2010, 5:58 am

Borax, Boric Acid Procedure ?

Hi again, I would like to thank the people that gave me advice on previous subjects. Always appreciated.

I have now processed my first batch of scrap material using the basic 'AR' method. Everything went extreemly well thanks to the handbook. However I have come to melting the gold into 3 bullion coins. When I melt the gold I cant seem to get a good colouration. I am using a graphite crucible that I am heating via gas furnace. I have boric acid and normall borax and have tried both. However the product seems to oxidise and turn a pink / bronze colour, and although this is very pretty I dont want to loose any product through extensive polishing. The discolouration is only a thin layer but I have seen this done and the foundries pour gold and it looks ready, besides a little polishing.

Has anybody got some advice on how to use the powders correctly, ie amounts, time of application etc. I may be putting the powder in to early or to late. I know im on the right tracks, I just have no experiance with melting gold.

As always advice would be greatly appreciated.
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leavemealone

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Post March 22nd, 2010, 7:53 am

Re: Borax, Boric Acid Procedure ?

However the product seems to oxidise and turn a pink / bronze colour,

Your powder was not washed well enough.The discoloration is other metals that dropped out with your gold when you precipitated from the AR.I almost always use AR(poormans),and although its incedibly fasy and absorbs more metal in less liquid,you can very easily run into problem if not done correctly.
You must always add small amounts of nitric(NaNo3 in my case) until almost all of the base metals are dissolved,then boil,boil,boil.You have to make sure that any gold the has dissolved into the AR is precipitated,and by saturating the solution with copper you will force any gold out of solution.So boil until you are sure that no more base metals are dissolving,decant the spent AR,and start a fresh batch,only this time the percentage of base metal to gold will be significantly lower.Even using this method,you still must wash your gold very well.Using this method,your powder will ALWAYS be dirtier than the dirtiest auric chloride(steves method).The reason for this is,using steves method you almost completely eliminating the base metals first,before dissolving the foils.
My advice is to flatten the button with a hammer on a clean hard surface,as flat as you can get it,redissolve with AR,precipitate,and wash well before melting.Good luck
Johnny
Everything that is gold,doesn't always glitter.
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Nitric

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Post March 22nd, 2010, 8:26 am

Re: Borax, Boric Acid Procedure ?

leavemealone, thanks for reply. excellent advice.

Could the base metals contaminating the gold be due to SMB ? I have never been to keen on the idea of precipitating this way. I did use heat aggitaion and regular stirring. Once the reation had completely finshed I added 3 small measures of HN03 to check for any further reaction. Seeing no further reation I assumed enough AR was present and continued to the first filter. I then added small spatulars of urea untill I was confident it was netrilized. Transfering the solution back to a large beaker I tested positive with stannous chloride solution and precipitaed with SMB.

I will definately refine it again like you have suggested, but is the SMB an issue using this method ?
Aaron.
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leavemealone

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Post March 22nd, 2010, 9:12 am

Re: Borax, Boric Acid Procedure ?

Could the base metals contaminating the gold be due to SMB ?

It's highly unlikely.I haven't used SMB in some time,but I never had a problem with it dropping too many base metals when I did use it.When using AR gold and copper tend to bond together molecularly.Unfortunately that is a drawback to using AR this way.When you try to precipitate,one of threes things happen,and they are usually based on how high the percentage is,of base metals in solution.
1: Gold drops,most likely with a little contamination.
This is the most likely result if you use AR the way I do.
2:Gold drops and is heavily contaminated.
This is the result of either not decanting the spent AR before your final dissolution,or decanting too early,hence leaving a high percentage of base metals behind to still be dissolved.
3:No precipitation at all.
This can be caused by multiple things.(A) the most predominant problem,neutralizing the nitrates.(B)too high of contamination of base metals.I have seen this a thousand times.
In your case number 1,or 2 was the result.Simply washing the powder will not be enough if it is too highly contaminated.You will need to redisolve in a small AR or AC bath and reprecipitate.Then your powder will be much cleaner,you will still need to do the 3,3,3 washes(water,acid,water)to get it as pure as you can.
Johnny
Everything that is gold,doesn't always glitter.
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shadybear

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Post March 22nd, 2010, 9:32 am

Re: Borax, Boric Acid Procedure ?

What color was the AR before you dropped?
You probably had drag down from your AR solution, was this your 1st drop or more on point was this the 1st drop of this material.
I agree the SMB doesnt dirty the gold but I have noticed that when using AR with a urea
neutralization of nitric the drop seems like it has a larger drag down.
re-run in AR you are not going to get the best results from just one drop unless it was extremely clean AR solution.
Dont forget the wash procedures after drop as well
Put the drop into hot HCL 1st I leave it for an hour or so, then decant rinse well with hot water, dry till it stops smoking, boil in Ammonia(I think this is a very important step)
then rinse well with hot water and decant four or five times then dry till no smoke, now here is where i differ a little, at this point I remove my dry powder and incinerate or more to the point heat with a torch to red but dont melt. then back into hot HCL. Rinse 4 or 5 times, you will notice how cleaner your powder is at this point and how quickly it settles.
Dry till no smoke and melt.
Just remember you cant expect to have great quality from a one time SMB drop from dirty AR.
And I would ask more about using the Graphite crucible most people dont use those for gold.
Last edited by shadybear on March 22nd, 2010, 9:38 am, edited 1 time in total.
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Nitric

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Post March 22nd, 2010, 9:37 am

Re: Borax, Boric Acid Procedure ?

leavemealone,
That makes perfect sense. I divided my scrap into 2 beakers. The first was 24kt plate material, the second was all 9ct jewlery containg high percentages of cu. I was expeting better results from the jewlery purely due to its mass, but the 24kt plate batch resulted in a much better couloration. And the SMB reacted in the plate solution correctly, the jewllery batch reaction appeared thinner and less consistant.
You were right about the cu, I just checked the coin I molded, the inner material has an obvious copper contamination. You can see just by its colour.

Thanks again for your advice, I will run it through the process again. Hopefully like you said I will now begin with alot less base metals and get better results.
Nice One. Aaron.
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Nitric

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Post March 22nd, 2010, 9:41 am

Re: Borax, Boric Acid Procedure ?

shadybear,

Thanks for the tip, I was aware of the ammonia step. I rinsed very well with HCI, left at 80 degrees. Rinsed with hot water. But I never used ammonia. I will give it a try. I did read the info on it but I went with just HCI as ammonia is not somthing we regualry use at the plant I work at. I will buy some and definateley give it a shot. Much appreciated.
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leavemealone

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Post March 22nd, 2010, 9:47 am

Re: Borax, Boric Acid Procedure ?

Shadybear wrote:
Dry till no smoke and melt.

Clean gold powder does not smoke.
dry till it stops smoking, boil in Ammonia(I think this is a very important step)

I have never used ammonia.I am sure it is a vital step for some members,I however have not used it as part of my recovery methods.I learned almost everything I know from steve and harold,and they never suggested that I use ammonia with any of my processes so I never have.Again that doesn't mean that it does not work for other members.
Aaron wrote:
Thanks again for your advice, I will run it through the process again. Hopefully like you said I will now begin with alot less base metals and get better results.

You are more than welcome bud.
Johnny
Everything that is gold,doesn't always glitter.
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Harold_V

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Post March 22nd, 2010, 1:25 pm

Re: Borax, Boric Acid Procedure ?

I used an ammonia process in washing fine gold. It removes traces of silver chloride that may have hitched a ride, plus it often removes traces of copper that have managed to get carried through the operations. My washing procedure included a prolonged boil in HCl, a rinse, a heated wash in ammonium hydroxide, followed by a rinse, then another HCl session. I stopped only when the fluid was colorless.

I attribute a great deal of my success to my washing procedures. The results speak for themselves.

Harold
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leavemealone

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Post March 22nd, 2010, 1:27 pm

Re: Borax, Boric Acid Procedure ?

Harold can you repost a pic of the entire bowl?I had it on here before I had to format,then lost it.
Thanks,
Johnny
Everything that is gold,doesn't always glitter.
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Harold_V

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Post March 22nd, 2010, 1:35 pm

Re: Borax, Boric Acid Procedure ?

leavemealone wrote:Harold can you repost a pic of the entire bowl?I had it on here before I had to format,then lost it.
Thanks,
Johnny

Johnny,

I checked my files and found the few pictures I have are all similar. None show the entire bowl. Sorry.

Harold
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Wise people talk because they have something to say. Fools talk because they have to say something.
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leavemealone

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Post March 22nd, 2010, 1:52 pm

Re: Borax, Boric Acid Procedure ?

OMG Im sorry,I just realized I can "scroll" down inside the pic.Yes that is the same pic I was looking for last week.Thanks harold.
Johnny
Everything that is gold,doesn't always glitter.
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Nitric

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Post March 24th, 2010, 8:20 am

Re: Borax, Boric Acid Procedure ?

Harold-V
Thanks for advice, im looking into ammonium hydroxide at the moment, I hadn't really seen the use for it before I saw my results. ' live n learn '. I am going to re-wash my product and im setting up a washing procedure with Hot HCI followed by ammonium hydroxide bath untill im confident its ready for a final dip in warm HCI then a rinse.

Following leavemealone's advice combined with a good wash procedure hopefully that should do it. See how it goes !
Thanks again !!

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