# white mud



## bbigpat (Jan 10, 2013)

in ar process , what would cause white mud, readung alot but havcent come across


----------



## butcher (Jan 10, 2013)

Much depends on what you processed and how you did it, many metals in acid can form white powders.

Flour is a white powder, talc from rock can be a white powder, and cocaine I hear is a white powder.

So giving an answer on what your white powder is would be hard to say, without knowing more about what you are working with, but even then the most we could do is guess with out being able to do tests to see what you have.

Below are some of the clues to test some of your white powders.

Do not sniff them up your nose :lol: 

The most common white powders you will probably run into are:

NaCl sodium chloride, table salt, HCl +NaOH --> NaCl + H2O, (the sodium metal salt we use to flavor food), which is soluble in cold water (more soluble in hot water but so is PbCl2 see below).

PbCl2 lead chloride, white powders often form needle like crystals, this lead metal salt is not very soluble in cold water (almost insoluble), but in boiling hot water becomes much more soluble (can be separated from AgCl with this method see below)

CuCl copper I chloride, a white powder, when dissolved in HCl will turn green or brown if very concentrated forming copper II chloride CuCl2 in solution (lead chloride or silver chloride would be insoluble in this solution).

AgCl silver chloride, a milky solution or white fluffy precipitant (that takes time to settle), insoluble in water hot or cold, insoluble in HCL or HNO3, can be dissolved in ammonia (but must be re-acidified for safety as dried powders can be dangerous), can also be dissolved in sodium thiosulfate, silver chloride when washed in water will darken in sunlight, used in photography bright light reduces it to silver metal over time.

jokeing around some here.


----------



## bbigpat (Jan 10, 2013)

LOL, I LOVE A GOOD SINCE OF HUMAR, READS LIKE YOU HAVE ONE. MAYBE I CAN TELL YOU WHAT I WAS WORKING WITH AND WHAT IUSED AND DID, AN DYOU COULD HELP ME PINPOINT, WHAT I NEED TO READ, TO EXTRACT THE GOLD. 
THANKS FOR BEING ENTERTAINING , REALLY :lol:


----------



## butcher (Jan 10, 2013)

Ok
I will try and help.

But drop the all capital letters, it is considered yelling, and is frowned upon, just like poor or lazy spelling or texting.

Explain what you did with what metals, as best as you can, and I will help you the best I can.
Be prepared if I see you did things wrong I will tell you, this way, maybe help you learn to do things right.
Maybe I can give some advice on how to test the white powders.


----------



## g_axelsson (Jan 14, 2013)

If this is from the pins you mentioned in another post, 5 troy ounces of melted computer pins, then I would guess that the white mud you are seeing is tin oxide.
Most gold plated contact pins from computers are plated on a base material of brass or bronze. In bronze you have tin and that becomes a white mud together with nitric acid.

Göran


----------



## bswartzwelder (Jan 14, 2013)

If you do like most beginners, you may have added way too much SMB to precipitate your gold. Once you have reached the saturation point, no more of a chemical will dissolve. When you reach that point, any chemical additions will settle to the bottom of whatever vessel you are using.


----------



## Mikemurphy (Mar 2, 2013)

If it is smb what is the best plan of attack to dissolve it.


----------



## butcher (Mar 3, 2013)

Well if it was too much sodium metabisulfite the white mud would not be SMB any longer.

Sodium metabisulfite itself is water soluble, but when you add SMB to the acidic chloride solution it changes it chemically, the SO2 gas forms, the SO2 gas would precipitate gold, base metals in solution with excess the sodium metabisulfite would make sulfate salts (like copper sulfate or some other salt) as well as sodium salts like sodium chloride, so if you used too much SMB you would have a variety of salts some soluble and others not so soluble, most of these salts would be soluble in water especially very hot water, some like silver sulfate, lead sulfate, and a few others would not be, so you could have some sulfates salts mixed your gold precipitate, as well as any silver chloride that made it this far, that will not easily wash out, here after washing out as much as you can with hot water, and a boil in HCl and hot water again, you may be able to clean the gold up enough for a second refining, but of coarse much depends on how clean the gold you dissolved in solution was (how much base metals were involved, and which ones), and how happy you got when pouring in that jar of SMB, into your solution, as to how to go from here, you may have to incinerate the gold powder to drive off sulfates, then give it a boil in HCl and hot water washes before moving on to the second refining.

I normally do a wash dilute sodium hydroxide to neutralize and convert chlorides to water soluble salts and wash again several times in hot water to remove as much chloride salts as possible before I incinerate the gold, as gold powder or silver for that matter are volatile when heated to red hot with chlorides involved, and I try to prevent my gold going up in smoke as much as possible.


----------



## NobleMetalWorks (Mar 3, 2013)

bbigpat said:


> in ar process , what would cause white mud, readung alot but havcent come across



You said:



> In AR Process



I assume you mean that the white mud developed while digesting metals in AR, it doesn't sound to me like you mean it appeared when you attempted to precipitate Au from AR.

If that is the case, and if you were digesting gold plated pins as someone else suggested you were asking about in another post, then I would take a wild guess and say that what you have is Metastannic Acid/Tin Oxide. I have run across a lot of military grade material lately that for whatever reason is gold plated over copper plated over a tin base. I haven't bothered to look up the reason for this, but I have seen a lot of it in connectors and pins as of late. 

You can test this by taking a small amount and attempting to dissolve it in AR. If it does not dissolve and is bright white in collar, and you have not attempted to precipitate, then it's probably Metastannic Acid/Tin Oxide.

If it is insoluble in AR, but has a grey color, it could possibly be Silver Chloride (AgCl). 

Regardless of which it is, you should filter it off and continue to precipitate your Au out of solution. A second Ar digestion, then decanting the Ar solution into a filter will ensure you remove all the insoluble material. You don't have to recover the Au first, this is only a suggestion, I always try to continue with the part that I am sure of before I start playing around with the mystery.

Scott


----------



## pslyde (Mar 25, 2013)

I think this thread just answered part of a question I had. I believe that I used too much SMB in one batch, and have a white-tan, sandy-looking powder that just won't go away. I have used cold, hot, and boiling water, ammonia, and hcl washes, but it is still there. I now believe this to be non-soluble salts.

I decided to use hcl and h202 to bring the gold back into solution. Now I have a beaker with a nice gold-colored solution, and the powder ramains in the bottom. I thought about just filtering it off and processing the gold as usual. Then later using lye and/or heat to process the powder separately. Or should I just keep washing, melt it all together, re-dissolve, and process again? Suggestions?


----------



## butcher (Mar 25, 2013)

If you have already put the gold back into solution, you should be able to let it sit until solution clears (not murky), then carefully decant and filter solution into another clean vessel (a suction tool and pipette are what I use to transfer liquids), leaving the salt behind.

I am not sure what those salts are but overuse of SMB, could have formed insoluble sulfates or sulfites.


----------

