Light blue color in pregnant nitric acid wash?

[cad]

Hello,

Does anyone know why i would have a light blue color in my nitric wash. This is also after i have droped silver with hcl. :?:

Also what is the best (quickest) gold percipitant from cold a/r?

Carl

 

[lazersteve]

Copper nitrate is blue, but can be light blue when diluted.

Most of the gold precipitants work equally as fast as long as the solution is free of base metals and oxidizers (ie: chlorine, peroxides, or nitrates).

In my opinion the 'fastest' way is with SO2 or one of it's related compounds (SMB or Sodium Sulfite).

Oxalic acid is slow to react and requires heating.

Dibutyl Carbitol, aka:BDG or DBC, is fast to extract the gold, but requires time for the layers to separate and then more time is spent in the clean up and precipitation stages.

Ferrous sulfate is as quick as SO2 and those related to it.

There are others like hydrazine, but they are carcinogens and not recommended for this reason.

Steve

 

[cad]

Hello,

Would copper nitrate likely come from copper in the ore? or contamination from some other source.


Is so2 gas still easily available? and does it get put in place before or after nitric acid is killed?

Carl

 

[butcher]

blue most likely copper or nickel,
from aqua regia you have a choice of using several chemical or replacement option to precipitate your gold, one of the main things is to get that nitric out first, evaporation is in my opinion best, heat (i dont boil hard it takes time) so be patient, Special caution here: your nitric in solution will concentrate untill it gets to a point of Azeotrope with solution and then it will start foaming and most of it will try to come out of solution all at once, foaming over and spilling your gold and hard work putting a frown on yer face, so giving your solution head room and slowww evaporation and watching the pot can be in your interest, till it gets real thick, almost to like syrup but not till it salts out, if you use Harolds advise of adding some gold it helps alot, the gold will dissolve and use up some of that nitric, or if you used GSP advice you wouldn't have ever used that much nitric anyways. ok now we have a syrup add some hydrochloric acid HCL, to rewet it you may see some fumes of NOx now do a second evaporation and a third last one add couple of drops of sulfuric acid for any lead, now you can dilute your solution I use at least 3 time the water some use up to 10X, this will help any silver precipitate decant and filter your gold solution.
now you can use the precipitant of your choice.
sodium metabisufite (SMB)
sodium sulfite
ferrous sulfate (easy to make)
are some of the easy ones to find, of coarse there are many more.
they all are fast and simple. most of your trouble will most likely come from nitric in solution.

 

[cad]

Thanks,

Evaporation ill try that. I have tried hot disolved urea that doesnt seem to work at this stage of the game but it could be someother error on my part.


It there a formula for dmg mixing other than navy bean? Do you mix with acetone or?

Your answers where great and informative. thanks for the time.

Carl

 

[butcher]

maybe I can learn somthing here, what is reference to DMG and navy beans? i dont understand?

 

[cad]

Some of the manuals Dukes and others refer to the measurement of things using common items for the quantities. (Navy Bean) But how much is a navy bean really . I am using powder dmg and need to mix it correctly. So i am a little stuck.

Have you ever heard of siver fluf percip. in nitric wash alone or does hcl or salt have to be present? i am having this occur and it mystifies me a little. :roll:

 

[jimdoc]

Search the forum for both of Hoke's books.
The smaller book on testing precious metals
explains all you need to know about DMG and
testing solutions. Sorry I can't point you to a link,
but I know it is on the forum.
Jim

 

[lazersteve]

The general reactions list in my Guided Tour Link below gives specifics for making 1% DMG test solution.

Silver 'fluff' from salt or HCl is silver chloride. It's white and darkens to purple when exposed to light.

Silver 'fluff' from the Copper cementation reaction is metallic silver.

Steve

 

[Harold_V]

Some of the manuals Dukes and others refer to the measurement of things using common items for the quantities. (Navy Bean) But how much is a navy bean really . I am using powder dmg and need to mix it correctly. So i am a little stuck.

Read Hoke.

A little tip. DMG is difficult to dissolve, but will dissolve readily in alcohol. You can use a little 190 proof to dissolve the amount needed, then dilute it with distilled water.

Have you ever heard of siver fluf percip. in nitric wash alone or does hcl or salt have to be present? i am having this occur and it mystifies me a little. :roll:

If you are using tap water, you can expect traces of silver to precipitate. If you are NOT using tap water, but distilled water instead, and you see some flocculence as the solution cools, it is likely lead nitrate, not silver.

Harold

 

[cad]

This forum is great.

Sometimes you just get stuck on the journey! I downloaded hoak's book on precious metals and got the recipe for dmg. thanks for the tip.

It is when something different happens that this pool of people really are helpful.

Carl

 

[donnybrook]

Carl,
Previously tried to respond. New to the Forum. Blue is usually copper (unless you have something like Cobalt in it ??). Copper can be blue or light green depending upon its valance pH 5 or say pH 8 can give two different colors. Potassium Ferrocyanide is used to determine what metal copper or cobalt?? One blue is very dark (azure blue). However don't go that way unless you have a lab. Bad stuff from my my point of view. But then some people are set up to do such things.

I have a very old book (110 years old) on assaying for the prospector.

Also the reference to DMG. I think you are referring to Dimethylgloxime used for Palladium which will produce an orange or red precipitate (memory failure). Ammonium Chloride will then recover the Platinum and then your gold with SMB. Or in the alternative sulphate of iron sometimes called Cupperas which is easily made by boiling this in water (purchased from a garden supply centre) or by boiling some iron in weak sulphuric.

You can take your Palladium with SMB in Nitric but I think you take any silver first, using hydrochloric or just salt in water then boil and add SMB to the heating Nitric.

Either way in just Nitric first to recover silver and Palladium or direct from AR (1) Palladium and DMG (orange), (2) Platinum and Ammonium Chloride (yellow), then Au and SMB (brown powder). You should roast your Palladium and Platinum powders to remove the salts of DMG and Ammonium Chloride and convert to Palladium and then Platinum Black. Weigh then assay or sell.

Donnybrook
Australia

 

[Harold_V]

Also the reference to DMG. I think you are referring to Dimethylgloxime used for Palladium which will produce an orange or red precipitate (memory failure).

DMG yields a very dark yellow precipitate from palladium. It is not recommended as a recovery procedure due to the huge volume of material produced, which is quite sticky and difficult to handle. Palladium is generally precipitated from solution with ammonium chloride and sodium chlorate. Hoke discusses the procedure in her book.

This picture shows the various salts of palladium.

The center sample was precipitated with DMG.
The red sample was precipitated with ammonium chloride and sodium chlorate.
The sample on the left is the result of dissolving the red powder in ammonium hydroxide, then precipitating with HCl.

Harold

 

[donnybrook]

Thanks Harold. Some very interesting information on recovering Palladium. Also great photos. I used DMG years ago and it did produce a lot of colored powder and little in the way of metals. It is not (or wasn't) worth a great deal recently. The price has been going up and down like a brides nightie. Apart from jewellers scrap;slags etc the only platinum and palladium I know of in Australia is up in north Queensland usually associated with the rock Serpentine. As I said it was a long time ago.

The old book I have is an "Everymans Edition" and platinum and palladium were of no interest or probably not regarded as something of value then. A bit like the black opal which they would discard but it is now worth a fortune.

Again thanks,
donnybrook