Thanks a ton!
Silver chloride conversion issues
- Thread starter icejj
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Thank you for your help. I'm not sure if I'm understanding everything correctly though, did you mean nitric when you mentioned nitrogen?? What is the "vinaigrette"?
No, this is the metallic silver that was poured out of the crucible into cold water, this is the melted silver that was in the crucible that contained both melted silver and the unmelted crumbled pieces. The crumbled pieces (which contain small pieces of melted silver buttons) was taken out of the crucible and placed on the left of the graphite mold in the corningware, while the melted silver was poured into cold water. To add clarity, the pictures do not contain any silver chloride prior to the lye/sugar conversion, everything in the pics is after the lye/sugar conversion. I probably should have stated this beforehand.
I think the Nitrogen is a typo.
Vinaigrette is Vinegar in French and since it is within hyphens I assume it is used in a transfered meaning.
Just as I thought.
And this seems to give a stronger indication that the conversion was incomplete.
I guess you cleaned the AgCl thorughly before adding the Lye?
Can you share how you did it?
Approximately amounts and so on?
in this case, the vinaigrette is in a figurative sense
original name means :
Vinegret (Russian: винегрет[1]) or Russian vinaigrette is a salad in Russian cuisine which is also popular in other post-Soviet states. This type of food includes diced cooked vegetables (red beets, potatoes, carrots), chopped onions, as well as sauerkraut and/or brined pickles.[2][3][4][5] Other ingredients, such as green peas or beans, are sometimes also added
You also have a salad of chlorides, oxides, metallic silver..
nitrogen - nitric acid
I performed several water rinses on the silver chloride until the rinse water was clear.
Then it would be safe to assume that it is mostly AgCl.
What was the origin of the AgCl?
Also worth noting. If you think you have contaminated chloride. AgCI2 is sensitivetp UV light. You can test it to visually see if it turns to an oxide.
Once’s the silver is converted to elemental silver (Ag+).
This will be light grey/light brownish in color depending on how much sugar you add.
Light Grey = 99.9%
Dark Grey = Other base metals 95%+
Less sugar = light grey in color and easier to wash. I usually just add handfuls at a time in large batches.
If you see the photo below. I created molasses with the silver oxide. That’s why it’s brown.
The lye/sugar solution can be neutralized with baking soda. Then simply discarded safely. If you don’t wash the additional sugar and lye it will also cause slag. Just wash the oxide powder and test with ph strip till it’s neutral. Then smelt away!
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kurtak
Well-known member
He answered that here ------
Note; - the following is being post to help icejj figure out his problem - as well as help other members - & is not directed to anyone in particular
Gold filled can be over almost any metal including over sterling silver & in fact gold filled over sterling is quite common
So after the nitric digestion (leach) the nitric should always be checked/tested for silver - which icejj did by adding salt to the nitrate solution to see if a chloride formed
However I would have tested the nitrate solution for silver different then testing with salt (or HCl) and here is why
As I said - gold filled can be over almost any other metal - & that includes lead - though it (gold filled) is rarely if ever put "directly" over lead
Rather - the lead will be used to give weight to a gold filled object - such as a pendent hung on a chain (necklace) & the lead will be used as a core/filler of the object with the shell of the object being made of a "thin" base metal (SS or copper/brass) which then has the gold filled over that thin base metal shell - &/or gold filled object are often made with tin/lead solders - this (lead) is not uncommon with gold filled
Lead dissolves in nitric - therefore it is entirely possible to end up with lead dissolved in your nitric when doing a batch of gold filled & salt or HCl will precipitate lead chloride - which looks just like silver chloride
But - lead chloride does not convert to actual lead with lye/sugar - like silver (chloride) does - so if you have both lead & silver in solution - the salt/HCl will precipitate both as chlorides - but only the silver will convert with the lye/sugar
Therefore - when processing gold filled - you are better served to test (& recover) any dissolved silver in the nitrate with copper which will cement out the silver & will leave the dissolved lead in the nitrate solution
Though (at this time) I don't know for sure - I "suspect" that icejj is likely dealing with both lead & silver chloride
Ways of testing for lead (which should always be done when processing gold filled) -----------
1) you can first test the solution to see if lead is dissolved by taking a small sample of the solution (a few ml) put it in a 50 ml beaker & add "a bit" of sulfuric acid - the sulfuric acid will precipitate lead sulfate - give it a bit of time for the lead sulfate to settle as if it is a small amount of lead you may not see the sulfate if you don't give it some time to settle
2) if you don't do the above test (to first test for lead) but instead go direct to precipitate with salt/HCl you can then test to see if what precipitated is - lead chloride - or silver chloride - or a combination of the two - by exposing the precipitated chloride to light (exposure to direct sun light is best)
Silver chloride - when exposed to light does what it called "photo greying" which causes the white silver chloride to darken (or grey)
How much &/or how fast it "greys" depends on the light it is exposed to - under artificial lighting (normal lighting in a room) it will take a fair amount of time before it starts to "grey" whereas with direct sun light it will happen "almost" instantly --- which is why I recommend exposing the chloride to direct sun light
How it greys - at first it will shift from white to brown or brownish grey - then to a more bluish grey - then a darker purple grey & finally to a black/grey & or even black
ALL silver compounds photo grey which is why it works for developing black & white photos (usually as silver sulfates) but even silver nitrate will photo grey - if you put a drop of silver nitrate on a paper towel & set it out in the sun it will go though the above color changes of the above photo greying process --- in direct sun light it will go from brown to black fairly quick under artificial light it may not go past brown &/or bluish grey
All that said - on the other hand - lead chloride does NOT photo grey - it remains white even if exposed to direct sun light
So exposure to sun light is the test to determine if salt/HCl has precipitated silver chloride - or lead chloride - or combination of silver/lead chloride
If you precipitated both silver & lead chloride the silver chloride will photo grey but the lead chloride will not - so you will end up with "white spots" mixed in the silver chloride that has photo greys - the white lead chloride spots will not go away no matter how long you leave it exposed to the sun
How to get rid of the lead chloride if you precipitated both silver & lead chloride with salt/HCl
Silver chloride does not dissolve in water - not even HOT water
Lead chloride does NOT dissolve well in cold water - BUT - it dissolves very well in HOT water - so if you dissolve the lead chloride with HOT water & then let that water cool back down - the lead chloride will precipitate back out of the water
So - if the photo grey test shows white spots of lead chloride mixed in with silver chloride you need to wash it (the chlorides) with HOT water (boiling hot preferred - you don't need to boil the chloride - just boil the water & then us it for washing)
You can test for when all of the lead chloride is washed out by simply letting the wash water cool back down - you know the lead chloride is washed out when no white cloud of lead chloride forms after cooling down
You can speed up the cooling down test by taking a small sample of the wash water (50 ml beaker or test tube) & putting it in a bowel of ice water - rather then waiting for a large volume of wash water to cool down
For what it is worth
Kurt
kurtak
Well-known member
First of all I want to say thank you for your contributions to this thread - good advice & well worded
However - per the bold print (above quote) in as much as that certainly works (adding the sugar to the lye water without first washing the lye out of silver oxide) I prefer to wash the lye out of the silver oxide before doing the sugar & here is why
When refining we create other acidic "waste" solutions - those acidic waste solutions need to be made safe for disposal - which is done by adjusting Ph - which can be done with ether a hydroxide or a carbonate
So - the hydroxide (lye) used to convert the silver chloride to silver oxide can be used to treat other acidic waste to make it safe for disposal
BUT - if you add sugar to that lye (water) & then try to use the lye/sugar water to treat other acidic waste to make it safe for disposal it will create a HUGE mess
Here is what happens - your lye/sugar/water should be around Ph12 (maybe if dilute enough Ph 11)
So - as soon as you start to add the lye/sugar water to your acidic waste it starts to create a "thick" sugar foam
This is the sugar precipitating out as the Ph starts to go down & the more lye/sugar water you add to acidic waste the more of this sugar foam you create - AND - it does not go away - it just keeps building up --- unlike the foam that settles after the reaction of adding just lye to acid
By the time you add enough lye/sugar water to acidic waste to get to a Ph of around 9.5 - 9 (which is not yet close to Ph 7 or neutral) you will have such a mass of sugar foam that you can't stir it to add more lye/sugar water to get the Ph down more - & that Ph 9 sugar foam will nether float or settle or filter (at around Ph 9) - even if you let it sit for a couple weeks - it just stays a mass of sugar foam
So you can't use the lye/sugar water to treat other acidic waste - whereas if you at least decant the first lye treatment &/or one or two washes before going to sugar treatment you can use that lye water for adjust Ph on other acidic waste
It is a bit of an extra step but it allows you to use your lye waste to treat acidic waste
& for what it is worth - in as much as regular sugar can/will work to reduce silver oxide to silver - Kero syrup is a better choice
Kero syrup is an actual "reducing" sugar whereas regular sugar is not considered an actual reducing sugar so Kero is more effective at taking away the oxygen atoms from the silver oxide
Kurt
The last 3 posts have quite a bit of great information in them.
I would like to add to.
What I see when chloride exposed to either sunlight or common light that has UV ultra violet wave length in it.
Guy reported the UV. I see a purple color or tinge depends on how much time is given in the light.
When the silver chloride is exposed to ultraviolet light in the UV-A spectral region, it forms tiny silver particles which absorb light.
Also noted the use of PH strips, even though the rinse is clear does not mean it is neutral. Keep that in mind.
There will be many times you need to be free of bases or acids chlorides and cannot know unless you use something to measure PH.
Kurtak has very good points on the Lead very hot water washes.
The wash between adding sugar to extend the use of Lye to use for neutralization of waste acid.
Also the exposure of UV light.
Karo syrup reducing sugar more effective.
Lots of super good info.
@GuyGuyGuythe1st I have had this brown a couple times and would like to know how to fix the issue.
What I have done is started all over again.
I would like to add to.
What I see when chloride exposed to either sunlight or common light that has UV ultra violet wave length in it.
Guy reported the UV. I see a purple color or tinge depends on how much time is given in the light.
When the silver chloride is exposed to ultraviolet light in the UV-A spectral region, it forms tiny silver particles which absorb light.
Also noted the use of PH strips, even though the rinse is clear does not mean it is neutral. Keep that in mind.
There will be many times you need to be free of bases or acids chlorides and cannot know unless you use something to measure PH.
Kurtak has very good points on the Lead very hot water washes.
The wash between adding sugar to extend the use of Lye to use for neutralization of waste acid.
Also the exposure of UV light.
Karo syrup reducing sugar more effective.
Lots of super good info.
@GuyGuyGuythe1st I have had this brown a couple times and would like to know how to fix the issue.
What I have done is started all over again.
This is how I take care of it.
Charge a crucible with the contaminated Chloride or oxide. It cannot be a melt dish. It has to be a furnace that gets hot enought and in a vessel that can be stirred at minimum 900C.
Add below while charging and melting the silver in the furnace.
25% Borax / 37.5% Lye / 37.5% Granulated Sugar.
Note: This is acidic flux. It will eat graphite crucibles for lunch.
I have a 3kg melting furnace. I charge about 1KG of material with less than 25-50 grams of the above mixture.
This will convert any stubborn compounds left not converted. The flux will also absorb any impurities and create a slag. When you go to pour it. It’s almost the same process as above but instead of hydrometallugry. It’s pyrometallurgy.
Once molten. Stir a few times with a graphite rod then cast. The flux will create slag resembling black glass. It will take all the impurities out. Once the silver and slag solidify but are still hot. Extract the silver bar out of the mold. Smack it with a hammer. It should remove all the flux. I have a wire wheel machine for any stubborn leftovers.
Save the slag for a later melt incase some of the silver doesn’t convert still. When your crucible is at the end of its life. Rinse and repeat the process.
This avoid hot water rinses. That may or may not work depending on a ton a variables. It’s the fastest method. Again in my opinion avoids having to repeat the dissolving process again.
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Nice.
But is it really acidic when it contains
Edit to correct number.
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More on lead chloride:
Lead chloride is a white precipitate. It can be prepared easily by mixing lead nitrate with dilute HCl acid or NaCl. But, as products HNO3 or NaNO3 can be formed in the aqueous phase while forming PbCl2 precipitate.
PbNO3 + HCl → PbCl2 + HNO3
This last point (3) when we add the Lye to convert to silver oxide and Kurtak mentions to wash (very hot water) rinse after this Lye addition is a point when the remainder of any lead chloride should be removed.
Lead chloride (PbCl2)
At times with our silver nitrate we have lead in it.Lead chloride is a white precipitate. It can be prepared easily by mixing lead nitrate with dilute HCl acid or NaCl. But, as products HNO3 or NaNO3 can be formed in the aqueous phase while forming PbCl2 precipitate.
PbNO3 + HCl → PbCl2 + HNO3
- Lead chloride is not soluble in ammonia solution as silver chloride. One option.
- But PbCl2 is soluble in concentrated HCl solution and give a coordination complex, [PbCl4]2-.
- As well, lead chloride is soluble in alkali hydroxide and hot water.
This last point (3) when we add the Lye to convert to silver oxide and Kurtak mentions to wash (very hot water) rinse after this Lye addition is a point when the remainder of any lead chloride should be removed.
Excellent, thank you Guy, I will write this down and try it out in the future.
Is that 900c degree's?
So the graphite crucible will be wasted, are they good for more than once? Before they are completely wasted.
The pour, this has to be done in a iron or steel Ladel vessel?
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My warning is overstated. Its acidic but not like melt your skin off in a mushroom cloud effect type of acid.
3-10 casting with this type of flux. Anymore than that. Your gambling with your own safety. I have had crucible fails before. Its scary as F***.
Yes 900C. Tin/Mercury/Lead chlorides all boil below this and start to carbonize or form other complexes. All lighter than the molten silver. The above flux absorbs that carbon and impurities as a "collector".
It's basically like oil and water. Oil will sit on top of the water because it lighter than the water. Same principle applies with molten metal because of their densities.
Graphite you can cast multiple times depending on type of metal and temperature used.
Higher temperature = More wear and tear less casting opportunism. Aggressive fluxes will also wear them.
Thank you ALL for your responses and insight. I certainly learned a lot that would help me in the future. As for my current problem, I'll try the solutions that were given and try to post an update sometime. If there are more potential solutions or anymore helpful info about silver chloride conversion then please keep them coming. I've concluded that there's a good chance that there is lead chloride contamination as well as the silver chloride conversion not being completed properly.
Martijn
Well-known member
There is the sulfuric acid and iron conversion method.
The secret for both methods working good, is well washed silver chloride.
