cleaning the white mud

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necromancer

necromancer

Well-known member
Joined
May 23, 2011
Messages
1,948
Location
Canada
just ran my very first ceramic cpu batch, it netted (26.1g gold)
cleaned off all heat sink grease tossed straight in to AR & am left with this white mud.

i am thinking its mostly silver:

how-to-clean-this.jpg

i need a little help cleaning this up, the gold turned out looking very good (needs to be melted) any suggestions on cleaning up this mud ??


thanks in advance

Dave C.
 
The simple solution? I would say take it all (including filters) and put it in a crucible with a sodium carbonate flux.
 
it was just over 18 pounds.
gold recovered was (after melt) 25.8g

thank you goldenchild !!, will need to buy a bigger crucible 8)
 
Digi, it's not about how many but what type.

I could sell you ceramic CPU at £6 per Kg but that's all you would ever get from the types I would sell you at that price.

Jon
 
2822.jpg

a great source of sodium carbonate, should this me mixed with borax ? or just sodium carbonate ?

never used it much, only just a little sprinkle to absorb impurities while melting
 
The sodium carbonate alone should suffice. Just be sure to use plenty of it. I would even incinerate the papers before putting them in the crucible. Not a heavy incineration but just enough to turn the paper into ash. Possibly with just a normal cigarette lighter. This will make the melt easier. Then put all the material in the crucible and cover it with sodium carbonate, WELL. If you don't there will most likely be losses. If using a furnace just insert the crucible and go. If using a melting dish start off very slow so that you get a nice liquid layer on top before turning up the torch. Melting dishes will be a bit trickier to avoid losses though. If you see blue flames and or white smoke you are losing silver.

P.S. You don't necessarily have to get a bigger crucible/melting dish as you could do it all in small increments. It would also probably be easier this way.
 
I don't think cpu's have a lot of silver. But I might be wrong. What did you do to the AR to
Get that back out? When I have done ceramic cpu's I break into a few pieces and dissolve then toss the ceramic. Is that powder coarse ceramic?
 
joubjonn said:
I don't think cpu's have a lot of silver. But I might be wrong. What did you do to the AR to
Get that back out? When I have done ceramic cpu's I break into a few pieces and dissolve then toss the ceramic. Is that powder coarse ceramic?
Click to expand...

that would depend, some have more silver then gold, this all comes down to the many factors, type, age, maker, design.........

my AR & 386/486 ceramic cpu process..... (off the top of my head) (thank you GRF !!!)

smash up ceramic cpu (8 or 10 parts), some were finely crushed (by someone else that "was" going to recover for me)
removed all kovar or Tungsten parts
(kovar metal plated in gold almost always on the bottom of the cpu)
(Tungsten, Pentium pro cpu have Tungsten tops under the top gold layer) (i did not process my Pentium pro cpus or gold top Pentium cpu's)

added smashed cpu to my beaker (or your choice of AR & heat poof container), i used a 4000ml beaker, it was 80% full with smashed cpu

estimate gold content to get an amount of acid to use (i guessed 1 troy ounce 31.1g) (cpu gold yields found on this great forum)

added tap water 75% of the way to the top of the smashed cpus

add acid,
Hoke states, 4 fluid ounces HCl / Muriatic + 1 fluid ounce 70% Nitric Acid (HNO3) dissolves 1 troy ounce gold.
This is equivalent to 3.8 mL HCl + 0.95 mL HNO3 per gram of gold.(thanks to Harold_V for the math)

I placed beaker in a vintage pyroceramic corningware dish with a 1/4" sand bed & placed on personally modified portable propane BBQ, it gets very hot on low heat

I let it get hot & let acids react & reaction complete left on heat for about 2 hours (now a beautiful yellow/orange colour,) (always do the math before starting your process for best results, never "wing it")

took two 2000ml beakers & filled 50% with ice & left to get glass nice and frosty (cold makes the silver / lead sink, no ice = very fine hard to filter white mud) (don't spend 10 hours filtering drip by drip by drip by drip... ok you get the point)

after 2000ml beakers are nice and cold i pour off excess water and then pour the 4000ml beaker with AR into the two 2000ml beakers

when 4000ml beaker has no more AR i added water to wash off leftover AuCl, swirl water around, pour wash water into the two 2000ml beakers

when 4000ml beaker has no more wash water i added more water to wash off all leftover AuCl, swirl water around, poured wash water into 2000ml beakers

added more water to 4000ml beaker (75% to top of smashed cpu) placed back on heat added 40ml muriatic acid & 10ml nitric acid, heated to very hot for 30 minutes, removed from heat and set to the side

took each 2000ml beaker with melted ice & AuCl, filtered into a brand new 20 litre bucket. (silver is at bottom of 2000ml beaker & gets filtered last)

rinced each 2000ml beaker with tap water in a spray bottle into filter & the 20 L bucket

took the wash water in the 4000ml beaker and poured into the two 2000ml beakers (ice was also added to both 2000ml beakers, just like before)
dumped processed cpu from 4000ml beaker into large strainer with filter on top of 20 L bucket and sprayed it down very well with tap water, done a visual check & the rub test on cpu parts (rubbing 2 cpu parts pinned sides together was very smooth)

removed all larger cpu parts after the second aqua regia digestion and filtered very well.

filtered each 2000ml beakers into the 20 L bucket

spray washing the filters well & changing to new filters between each 2000ml beaker that i poured into the 20 L bucket (white mud was collected in each filter & filter paper was opened & left aside)

added about 30 drops (2ml) of 93% sulfuric acid to the 20 L bucket of AuCl, stired. left for a few minutes to drop any lead

took the AuCl in the 20 L bucket filtered again before I filled up the 4000ml beaker & the two 2000ml beakers & sprayed down 20 L bucket with tap water

mixed 50 grams of SMB in 100ml of boiling hot water till no more powder present

added 1ml liquid SMB to 4000ml beaker (no reaction from addition of smb = no free nitric acid) (reaction to free nitric = brown off gassing, bubbling or other)

added 50% of the liquid SMB to the 4000ml beaker of AuCl
added 25% of the liquid SMB to each of the 2000ml beakers of AuCl

let beakers settle tested with Q-Tip and SnCl2 (negative) & then decanted into the 20 L bucket filtering first

tested liquid in 20 L bucket with Q-Tip and SnCl2 (negative)

added negitive tested liquids to waste bottle (30 L wine making bottle)

took dropped gold mud and put into a 250ml beaker, added 50ml muriatic acid, boiled & poured off discoloured liquid & repeated 2 other times.
all excess muriatic wash poured off into another 250ml beaker, tested wash liquid with Q-Tip and SnCl2 (positive)
took 100ml negitive tested liquids from waste bottle and dropped gold left in wash muriatic acid, tested wash liquid with Q-Tip and SnCl2 (negitive) (using excess SMB let me recycle my waste liquids for the the SMB left over in its solution) (i recycle everything i can)

took all gold mud heated with torch till red hot (i use 1/2 the metal case from a floppy drive to dry my powders)

took dropped, incenorated gold powder and put into a 250ml beaker, added 50ml tap water, boiled & poured off clear liquid & repeted 2 other times.
tested wash water with Q-Tip and SnCl2 (negative)

took all of the white mud filters & hand washed in tap water inside a 5 L bucket, filtered and was left with what you see in the photo.

took dried gold powder & weighed, then prepared melting dish (thanks laser_steve)
put propane torch on bottom of melting dish (to keep dish bottom extra hot) used mapp gas & burnz "O" matic TS4000 to melt gold (was done melting in a few short minutes)

whole recovery / refining process took about 12 hours
i am not including time it took to originally gather ceramic CPU or to clean off the heatsink grease.
thats about the same amount of time it took me to type this out LOL

sorry for spelling errors, no spell check on this laptop, will fix after

comments, questions or if you think i missed something

this took me almost 3 hours to type out (2 finger typer) :oops:

Dave Clarke

EDIT spelling errors fixed
EDIT added "removed all larger cpu parts after the second aqua regia digestion and filtered very well."
 
If I am following your description of the process correctly, the finely ground ceramics were obviously part of the undissolved material which you filtered from the aqua regia after the digestion. Is that what is in the picture?

The silver will form silver chloride and the majority of it will be in the insolubles from the aqua regia digestion. That would mean they are in with the ceramics. Have you tried digesting your suspected silver chloride in ammonia to be sure it is soluble. I think most of that pile is ground up alumina ceramic from the ground up material you added.

The silver and lead chlorides that come out of the acid when you ice it are only what was dissolved in the acid when the acid was filtered, if you check out the solubility curves for silver chloride you will see it is never a lot and it drops off exponentially on cooling (which is why it is iced). Is the pile in the picture what was filtered after icing?

I would guess, pending answers about when in the process that pile was filtered out, that the pile is mostly ceramic substrate and silver chloride.
 
With all that dilution it could be white copper chloride like in the ap process. I doubt there is much silver in there.
 
4metals said:
If I am following your description of the process correctly, the finely ground ceramics were obviously part of the undissolved material which you filtered from the aqua regia after the digestion. Is that what is in the picture?
Click to expand...

yes it is, i did not include above that i removed all larger cpu parts after the second aqua regia digestion and filtered very well. (will add this part today)

4metals said:
The silver will form silver chloride and the majority of it will be in the insolubles from the aqua regia digestion. That would mean they are in with the ceramics. Have you tried digesting your suspected silver chloride in ammonia to be sure it is soluble. I think most of that pile is ground up alumina ceramic from the ground up material you added.
Click to expand...

no, i have not tried ammonia (it's on my "to buy list") will buy today by "alumina ceramic" you mean (type of crushed glass ?)

4metals said:
The silver and lead chlorides that come out of the acid when you ice it are only what was dissolved in the acid when the acid was filtered, if you check out the solubility curves for silver chloride you will see it is never a lot and it drops off exponentially on cooling (which is why it is iced). Is the pile in the picture what was filtered after icing?
Click to expand...

white mud is everything that was in the aqua regia digestion or in the wash process, i always swirled the liquids to pick up the lighter insolubles left in the bottom.

4metals said:
I would guess, pending answers about when in the process that pile was filtered out, that the pile is mostly ceramic substrate and silver chloride.
Click to expand...

i had at least 15 total filterings (or more) i didnt want to miss one single drop 8)
 
Palladium said:
With all that dilution it could be white copper chloride like in the ap process. I doubt there is much silver in there.
Click to expand...

thank you for that !!

on my todo list

ammonia test
melting
sun light test

thank you
 
4metals said:
The silver will form silver chloride and the majority of it will be in the insolubles from the aqua regia digestion. That would mean they are in with the ceramics. Have you tried digesting your suspected silver chloride in ammonia to be sure it is soluble. I think most of that pile is ground up alumina ceramic from the ground up material you added.
Click to expand...

This ^^^^ exactly.

I find that the vast majority immediately precipitates out as Silver Chloride in the AR and is caught in the filtering process. It's pretty logical since the HCl in the AR will react with the Ag. As such I get very little (if any) silver contamination when dropping the gold from the filtered AR.

I still don't know what material those tiny little rings are, that always appear in the bottom of a processed set of ceramics though 8)
 
spaceships said:
I still don't know what material those tiny little rings are, that always appear in the bottom of a processed set of ceramics though 8)
Click to expand...

they are foam bumpers off AMD ceramic cpu, they keep the heatsink level with the centre of the chip
look at your AMD cpu, the ones made just after the Alu top AMD cpu.
you will see one in each corner of the cpu
 
No Dave, thanks for the answer but I don't refine those rubbish chips I trade them for $80 per KG 8)

I mean the tiny tiny little metal rings that end up at the bottom of your AR. They are about a mm across.
 

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