# AgCl converted



## Grassbur (Dec 4, 2011)

Hello all i have a few questions about silver chloride conversion. 
The conversion method i used was sodium hydroxide and then table sugar to give elemental silver.
I have Steve’s video and was attempting to simulate.
After the conversion the end result looked very similar to the cementing process of silver nitrate with copper, however it did still have some characteristics of the AgCl.
The product was still clumpy after i had washed and dry. I then used a small amount of the final product to make an anode for my silver cell.
During the melting process it did give off a white smoke, from which i have read that AgCl if incinerated will give the white smoke. It did become molten so i could pour an anode.

Here is the question that i have. if all of the silver chloride did not completely convert ( I’m afraid that i did not use enough lye before adding dextrose ) would i be able to put the product into a beaker add water and use more lye to complete the process then add table sugar? Have i completely botched the silver chloride and have to take the loss when melting anodes or will going back to the conversion process finish converting the remaining amount? Is there a step that i might have missed or is this normal? I have read that if too much lye is used this can be bad. This was my first attempt to convert AgCl to elemental Ag. So i do expect mistakes on my part.


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## 4metals (Dec 4, 2011)

If you have the proportions of sodium hydroxide and sugar correct the conversion should be complete, however mixing is critical and a lack of it usually causes the chlorides to clump and not react completely. 

I have 1 client who reacts the silver nitrate solution coming out of his silver cells daily with HCl to form silver chloride. This is filtered and rinsed well and water is added to slurry the chlorides. The copper concentration in the water is checked with copper test papers and if found to be below 10 PPM the process of adding caustic and and sugar begins. If the copper is below 10 PPM the silver dropped will assay in excess of .999 fine.

I know GSP will be reading this and be thinking why go to the chloride step when cementing with copper yields .99 and perfect feed-stock for your silver cell. In this clients case, we're talking about solution running 80 grams silver per liter and we're changing 1200 liters per day. That translates into 3000 ounces of silver which is either marketable as .999 directly after treatment, or finely divided enough to be easily digested and upgraded chemically to .9999 and sold at a premium.


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## Lino1406 (Dec 4, 2011)

If you add sodium carbonate during melting
that will resolve your problem


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## Juan Manuel Arcos Frank (Dec 7, 2011)

Grassbur:

Working with silver chloride???...mmmm...let me share with you some tricks about it:

-First of all,silver chloride(AgCl) must be completly white.You can acheive this by washing silver chloride with hot tap water,besides,hot water causes AgCl to agglomerate pretty good.

-When you add lye to silver chloride mix well the solution with a rod,to konw when all silver chloride(white) has reacted to silver oxide(black) you can use this rule of thumbip the rod into the black mud for a couple of seconds,pick up the rod and see if there is any white grains on the road...if it is means that you still have silver chloride and must mix the solution for more time or add more lye.

-Personally,I prefer iron cementation rather than Lye/karo syrup process...Starting with white silver chloride add some iron nails,add a little bit of hydrochloric acid and start mixing(hot will be released),white mud will change to gray/green mud,pour off,from time to time the liquid formed(FeCl3).Iron cementation process will lead you to 0.99 silver,by melting with oxidant fluxes(like saltpeter) you can get 0.997-0.999 silver. 

I hope this helps.

Kindest regards.

Manuel.


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## goldenchild (Dec 7, 2011)

Juan Manuel Arcos Frank said:


> When you add lye to silver chloride mix well the solution with a rod,to konw when all silver chloride(white) has reacted to silver oxide(black) you can use this rule of thumbip the rod into the black mud for a couple of seconds,pick up the rod and see if there is any white grains on the road...if it is means that you still have silver chloride and must mix the solution for more time or add more lye.



Do you see any downfalls in melting the silver oxide and skipping the kyro? I thought that melting the oxide would result in losses but I remember one of the moderators saying there would be no losses.


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## Grassbur (Dec 7, 2011)

Thank you guys for the info that has been given thus far.

to Lino: is there a ratio of sodium carbonate that i should use? and will it hurt a graphite crucible in an electric furnice or should i use my pottery kiln for this, luckly i have the option of both types of heating as well as a maap torch? Also is there a temp. that i should keep it at for a certian time? Another question that comes to mind is would i mix this in the powder b4 adding to a crucible or apply it like borax?

to Juan: thank you for the advice, at the time the sodium hydroxide was the only method i had learned of to convert AgCl, after more dilligent research it seems the sulfuric acid conversion with Fe, Zn, Al, as mentioned in other forums for conversions seems to be a much easier method to use and i will attempt these on future batches that i will need to deal with.

when i get back to my farm to finish this. i will take some pictures and post. the one picture i do have is my first sample of the conversion


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## Grassbur (Dec 7, 2011)

the beaker on the right was the small sample i converted while watching steve's video i was in the process of washing it at the time the pic was taken, i had since converted both beakers by the time i got back to my shop.


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## samuel-a (Dec 8, 2011)

Grassbur said:


> to Lino: is there a ratio of sodium carbonate that i should use? and will it hurt a graphite crucible in an electric furnice or should i use my pottery kiln for this, luckly i have the option of both types of heating as well as a maap torch? Also is there a temp. that i should keep it at for a certian time? Another question that comes to mind is would i mix this in the powder b4 adding to a crucible or apply it like borax?



AgCl should be very dry and finely divided (pulverised with mortar and pestle)
You should mix them intimately while both powders are dry.

Theoretically, the reaction goes in the following order:

Na2CO3 + 2 AgCl + (heat) = Ag2CO3 + 2 NaCl --->
Ag2CO3 + (heat) = Ag2O + CO2 --->
2 Ag2O + (heat) = 4 Ag + O2

Practically, it all happens quite fast and not necessarily in that order.

From the first equation, you can see that for every gram of dry AgCl you will need 0.37 grams Na2CO3.

From time to time, when i actually do this convestion, i like to use a little extra carbonate, just to be safe, i'm addind 0.45g carbonate for each gram AgCl.
I then mix thoroughly, put in crucible and hold it at 400-450 C for 10-15 minutes, then the temp' is ramped up to melt the silver and pour anode bar.
This may not be the best procedure, but works for me.

*Personally*, i've come to understand, that i really don't like spending so much time converting AgCl with wet methods...

The carbonate will chew up the crucible and internal lining of the furnace.
Graphite crucibles are very good for this procedure, since they do not get attacked by the carbonate.
Also, since most of the O2 is generated and gassed off way before the crucible temp' is sufficient to support CO2 generation.


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## HAuCl4 (Dec 8, 2011)

4metals said:


> If you have the proportions of sodium hydroxide and sugar correct the conversion should be complete, however mixing is critical and a lack of it usually causes the chlorides to clump and not react completely.
> 
> I have 1 client who reacts the silver nitrate solution coming out of his silver cells daily with HCl to form silver chloride. This is filtered and rinsed well and water is added to slurry the chlorides. The copper concentration in the water is checked with copper test papers and if found to be below 10 PPM the process of adding caustic and and sugar begins. If the copper is below 10 PPM the silver dropped will assay in excess of .999 fine.
> 
> I know GSP will be reading this and be thinking why go to the chloride step when cementing with copper yields .99 and perfect feed-stock for your silver cell. In this clients case, we're talking about solution running 80 grams silver per liter and we're changing 1200 liters per day. That translates into 3000 ounces of silver which is either marketable as .999 directly after treatment, or finely divided enough to be easily digested and upgraded chemically to .9999 and sold at a premium.


Interesting 4 metals. I'd have thought that electrowinning the silver from the solution with a graphite anode cell/cells would have been faster, cleaner, cheaper. It could also be incorporated as a parallel continuous process into the existing electrolytical setup. Opinions?.


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## 4metals (Dec 8, 2011)

There is a company called Electrometals http://www.electrometals.com.au/ that sells equipment to do just that. The equipment is not cheap. 

Generally this forum speaks to the small scale refiner and that is where the chloride to metal conversion really shines. My client who converts 1200 liters per day of solution might benefit from their technology, OH, did I mention that he is a tightwad?


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## HAuCl4 (Dec 8, 2011)

4metals said:


> OH, did I mention that he is a tightwad?


Aren't they all?. :lol: 

Thanks for the link. 8)


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## Westerngs (Dec 9, 2011)

For those that stick to the sodium hydroxide/sugar method: (I like it, if done properly it is a very fast way to get silver metal from silver nitrate solution)

Note that for proper conversion of silver chloride to silver oxide the solution needs to get pretty hot, around 160F at least. Further, the silver oxide reduction with sugar also needs to be done at around this temperature.

Both reactions are exothermic (they generate heat), but if you a large volume of solution the heat generated may not be enough so heat needs to be applied.

Also, monitor the pH. Sodium hydroxide needs to be added to pH >12 for proper conversion to silver oxide. And do not go below pH 8 when adding sugar to reduce silver as it redissolves silver.

Best of luck.


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## butcher (Dec 9, 2011)

Westerngs, thanks, for the information on processing silver chloride and the conversion to oxide's, the pH tip I do not remember hearing about it, I useally go by color change of the salts.

my only comment here, if we have silver nitrate, copper cementation would be my choice to cement silver metal this can be melted without conversion and you loose less silver.

avoid silver chloride when possible. but when I cannot I will use your pH instructions thanks.


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## Westerngs (Dec 9, 2011)

Copper cementation works great, but it takes too long for my taste. For a 250 gallon tank with say 100 g/l Ag it takes about 2-3 days to cement out all silver.

I prefer the conversion method because if properly done the entire process can be done in about 1/2 hour. The silver can be filter pressed quickly and is then generally dry enough to smelt/melt. I experience silver losses <0.1% and have been using this method for about 10 years and recovered many thousands of ounces of silver.


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## Grassbur (Dec 10, 2011)

for those that might have been wondering the method i used to attain AgCl was: dissolved silver in nitric acid and cemented with a copper buss bar when the reaction had almost stoped after 2 hrs. i filtered the cement out of solution. then made up some salter water with rock salt. added to the solution until no more silver precipitated filtered AgCl out of solution and stored until i had a 3000ml beaker 2/3 full before i started to work with AgCl. this was mainly done as a time saver on my part bc my shop is at my farm 100 miles away from the house and only have the weekend to do the work. so the silver chloride was saved untill i had a resonable amount to work with. i probly will not use the lye/sugar method again i didnt like the process too much, more then likely i will use sulfuric acid with Fe/Zn/Al on the next batch i end up with. i am thinking of a way to have a constant aggitator in the solution to make the AgCl become intimatly in contact with the lesser metal. i will make a decission when that time comes, for the method i will use. one of the reason's i am going to try a different proccess is mainly to learn the different ways that the conversion can take place and what might can go wrong.. i honestly wish i had split the amount of AgCl into different beakers and tried several of the methods. if for any reason other then haveing the experience of doing the same thing different ways so that i can find the method that will work best for me. the main reason i ended up with the problem in the beggining post was bc i hadnt done my due dilligence of reasearching all the methods.

i do want to thank everyone that has provided alternative methods of what i had not discoverd yet.


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## Lino1406 (Dec 11, 2011)

If the starting point is silver nitrate,
all you need is caustic soda, then rinsing
with distilled water, then - melting


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## goldsilverpro (Dec 11, 2011)

4metals said:


> If you have the proportions of sodium hydroxide and sugar correct the conversion should be complete, however mixing is critical and a lack of it usually causes the chlorides to clump and not react completely.
> 
> I have 1 client who reacts the silver nitrate solution coming out of his silver cells daily with HCl to form silver chloride. This is filtered and rinsed well and water is added to slurry the chlorides. The copper concentration in the water is checked with copper test papers and if found to be below 10 PPM the process of adding caustic and and sugar begins. If the copper is below 10 PPM the silver dropped will assay in excess of .999 fine.
> 
> I know GSP will be reading this and be thinking why go to the chloride step when cementing with copper yields .99 and perfect feed-stock for your silver cell. In this clients case, we're talking about solution running 80 grams silver per liter and we're changing 1200 liters per day. That translates into 3000 ounces of silver which is either marketable as .999 directly after treatment, or finely divided enough to be easily digested and upgraded chemically to .9999 and sold at a premium.



Actually, there are certain applications where I intentionally produce AgCl. In one case, I was processing about 50,000# of stainless scrap that contained about 1-2% Ag (500-1000#) as a braze. The brazed also contained about 10% copper. I put the parts in stainless mesh trays and lowered them into a stainless tank containing 50/50 room temperature nitric acid - I bobbed them up and down occasionally. A 2nd tank provided a rinse. After quite a few batches, when the dissolving rate slowed down, I pumped the solution into a plastic tank and harvested 90% of the Ag with HCl. I first analyzed the solution for Ag and then added enough HCl to precipitate ONLY 90%. By only dropping 90% of the Ag, I ended up with NO free HCl and, therefore, wouldn't form AR and attack the stainless tank. Also, the H+ ion from the HCl combined with the NO3- liberated from the silver nitrate somewhat rejuvenated the nitric acid. By doing this and by making occasional additions of nitric, I ran the solution until it was pretty well saturated with copper nitrate.

In general, the success you get with converting AgCl to Ag using chemical methods, as far as the purity and the percentage of Ag actually converted is concerned, depends on how you handle the AgCl. It must be keep wet, from the time you add the HCl until you are reducing it with iron or something like Karo syrup/NaOH. If the AgCl dries, it changes from a lot of separate particles to crystals. When chemically converting to Ag, the conversion occurs only on the surface of the crystal. This can coat the crystal and trap unconverted AgCl inside. When working with dried AgCl, you must first pulverize it - at least 100 mesh would be nice. 

Also, you must rinse all the copper solution out to get a good purity. With the above mentioned 50,000#, I rinsed (and stirred and settled and poured off) the AgCl quickly in buckets, about 10 times, or at least to the point where the rinse tested negative for copper. When I poured off the rinse, I didn't worry about losing a little AgCl (maybe 1% total). I knew I would get it later.

If filtering, AgCl, in bulk, is one of the most difficult things to filter and rinse on the planet. If 2 or 3" thick, it will likely shortly slow to a drip every 2 seconds, especially if aged at all. Aging seems to occur even if kept under water. I found that fresh AgCl makes an excellent filter aid for old AgCl. I dissolved enough silver in nitric to end up with about a 1/4"-1/2" thick layer in the vacuum filter. I dropped the silver with HCl and IMMEDIATELY filtered it. I then, immediately, poured in a slurry of the AgCl I wanted to filter. This arrangement allowed me to rinse quite quickly. Then, I got it reducing in the Karo/NaOH in short order.
Large qua


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## kadriver (Jan 2, 2012)

goldsilverpro said:


> Actually, there are certain applications where I intentionally produce AgCl. In one case, I was processing about 50,000# of stainless scrap that contained about 1-2% Ag (500-1000#) as a braze. The brazed also contained about 10% copper. I put the parts in stainless mesh trays and lowered them into a stainless tank containing 50/50 room temperature nitric acid



goldsilverpro:

I concluded from your description above that nitric acid will not dissolve stainless steel, but aqua regia will.

If this statement is true, then I would like to ask you two questions (for my own knowlege):

1) Will hydrochloric acid - by itself - dissolve stainless steel?

2) Will hydrochloric acid, mixed with bleach, dissolve stainless steel?

Thank you - kadriver


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## Geraldo (Jan 3, 2012)

kadriver said:


> goldsilverpro said:
> 
> 
> > Actually, there are certain applications where I intentionally produce AgCl. In one case, I was processing about 50,000# of stainless scrap that contained about 1-2% Ag (500-1000#) as a braze. The brazed also contained about 10% copper. I put the parts in stainless mesh trays and lowered them into a stainless tank containing 50/50 room temperature nitric acid
> ...



I am not goldsilverpro (obviously - I have a very long way to go to catch up to his level of expertise), but I would like to take a quick shot at this. I haven't tried to dissolve stainless steel - most of my efforts with stainless have been in preventing corrosion, not causing it.

The way normal stainless steels (304, 316, 17-4PH etc.) work is that they form a very adherent oxide layer on their surface (nominally Cr7O23) which prevents further oxidation (corrosion). When that layer is injured somehow, it "self heals" if it is in a sufficiently oxidizing environment, so overall it corrodes slowly under the right conditions. This layer is often called a "passive" layer and the formation process is called "passivation."

Commercially, new stainless steel is often passivated before being put into service - the user intentionally "corrodes" the stainless to form a strong Cr7O23 layer. The two most common ways of doing this are to use dilute nitric acid, and dilute sulfuric acid/hydrogen peroxide. The acidity cleans the surface, while the strong oxidizer oxidizes the chromium to form that chromium oxide passive layer. So - no, nitric actually SLOWS stainless corrosion, rather than corroding it.

Stainless steels (particularly the austenitic varieties - 304, 316, 321...) have an Achilles heal - chlorides. These cause pitting (tiny corrosion points all over the surface) by destabilizing the chromium oxide layer and preventing its complete formation. For stainless that hasn't been passivated, even tap water can cause pitting. So - hydrochloric acid is very bad for stainless, and I suppose enough of it would dissolve it away entirely.

In aqua regia, the HCL would corrode the stainless, however the nitric would actually slow the corrosion by helping the stainless form a protective oxide layer. I suggest that stainless will corrode faster in HCL alone than in aqua regia.

For hydrochloric acid + bleach (perchlorate) - the HCL would be doing the heavy lifting, and I doubt that the perchlorate would actually help the process much, as again it would provide a strong oxidizer to work against corrosion. I don't think the chlorine tied up in bleach would significantly enhance corrosion. Austenitic stainless steels are used in parts of the bleach production process (just not parts with lots of free chlorides present).

I would suggest that HCL alone is a good start if you are trying to dissolve stainless. Adding salt or magnesium chloride should speed up the corrosion. A strong REDUCER would really help, but unfortunately most hydrometallurgical reducers are horrible and wretched (like hydrazine and H2S). Magnesium chloride, BTW, is a good complexing agent that really helps dissolve a lot of stuff. There are hydromet processes (small, secret processes) that use strong MgCl2 solutions to selectively leach various nonferrous metals. It's cheap too.

The final thing I would add is that dissolving "stainless steel" isn't like dissolving "gold" or "silver" etc. You are trying to digest 3 different metals simultaneously - chromium, nickel and iron. They each have different solubilities in different solutions.

So:
1. HCL probably the best bet. Could bump up the activity with NaCl or MgCl.
2. HCL + bleach is probably worse than HCL alone. Save the bleach for something else.
3. HCL + MgCl + a strong reducing agent is probably the best for fast dissolution, but yucky in practice.

Best Regards, Gerald


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## goldsilverpro (Jan 3, 2012)

In my experience, AR will dissolve stainless rapidly when strong and hot - more rapidly than HCl. 

304 SS is the best to use for nitric (only) in any strength. The drums that nitric is shipped in are 304 SS. The difference in 316 and 304 is that 316 contains Molybedenum and 304 doesn't. The 316 is attacked very slowly by nitric. There is a simple spot test that reacts with the Moly to distinguish 316 from 304.



> According to ASTM STP 550, possibly available from the ASTM, the test for molybdenum in 300 series stainless is to:
> 
> a) Place equal drops of concentrated hydrochloric acid and concentrated nitric acid on the metal surface. Allow 3 to 4 minutes for reaction and transfer 2 drops to a spot plate.
> 
> ...



The passivation of stainless is explained pretty well in this article.
http://cartech.com/techarticles.aspx?id=1456

The opposite of passivation, which forms protective oxides, is acid pickling, which removes the oxides on the surface so it can be subsequently plated. Weak solutions of HCl, H2SO4, or H3PO4 are common pickling solutions for SS.

In any case, keep HCl, table salt + acid, or any other chloride, in any strength, away from any form of SS. At the least, you could experience etching.


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## kadriver (Jan 3, 2012)

Excellent - thank you both for your responses, this is exactly the kind of information I was looking for.

I am doing some research to try and gather information for a project; recovering platinum from metal foil type catalytic converters.

Not very much info or experience here on the forum concerning this topic (metal foil cats).

I know this is the Silver index, so I am moving to the PGM (Platinum Group Metals) index so as not to confuse the forum.

See you in the PGM index.

kadriver


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## richardbal (Jan 15, 2012)

Hi Guys
nice and verry important information around AGCL.
well i have a problem with Chrom?????
i have run a hot sulfuric acid cell with a bit nitric acid on plated silver scrap.
well it working verry nice i get the silver verry quick out of the scrap!!!
and diluate the solution 4 time more water and cemented with salt
Agcl is verry clear .till this stap is no problem but the big problem is when i metl the silver after wash and cimentation i have always chrom??
91 silver % and about 6% chrom and some cu and fe but verry verry litell%
so my question is how the people talk in this forum about 99 % purty i never get that??
what is the problem then
i made many many ways to have 99 % silver is no way
always i have not more then 91%pur silver
any help????
thanks for all.
richard


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## Geo (Jan 15, 2012)

set up a Thum cell to refine your silver.the subject has been discussed many times on the forum.im not sure if 91% is pure enough as it will foul the eletrolyte pretty quickly.try redissolving with clean nitric acid and cementing with clean copper.that should bring the purity up enough to use the thum cell.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=12019

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=8589

look at these two links for ideas.


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## richardbal (Jan 15, 2012)

thanks geo

well u r right to setup a electrolyses?? is fine and easy but isnt the goal??
my question is why i have this contamination of chrom??????
why when i fall the solution with tabel salt and after cementation with Al wire in a sulfuric acide ????? normaly all other metal will go into the solution and just the silver will be cemented right???
thanks you for your help
need some new idees


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## jimdoc (Jan 15, 2012)

richardbal said:


> thanks geo
> well u r right to setup a electrolyses??



Just to let you know, "you are" is not spelled "u r", that is texting lingo and isn't allowed on the forum.
Changing that habit while you are on the forum will keep you here to continue learning.

Thanks. Jim


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## richardbal (Jan 15, 2012)

Hello Jim
sorry i didnt read the rools of your forum .if that a problem for you my way !then i am sorry verry sorry.
from now i will writ you are as you are
thanks


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## jimdoc (Jan 15, 2012)

There is the no texting lingo rule,the no double posting rule, and the no spamming rule.
And always have respect for all members rule. 
Its not too much to ask to help keep the forum neater, safer, and avoid problems.
Texting lingo is hard on the eyes, and can be written and deciphered in too many variables.

Shortcuts like DMG is acceptable, because dimethylglyoxime would probably be misspelled more
than Hoke. I think I have seen that four letter word (Hoke) misspelled at least a dozen different ways.

Thanks Jim


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## richardbal (Jan 16, 2012)

Hello Jim
you are right and i agree.the forum must be clear for all.thank you for your advice,i will try always to kip my english always correct!
but let me tell you that i have never learn or studies english in my life .is just beach accademy
is mean i learn it from internet people travels and so on
so sometime i dont know the right wrod so i use what i have heard or read somewhere
richard


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## nickvc (Jan 17, 2012)

The forum is quite tolerant of those that don't use English as their first language.
As this seems to be true in your case don't over worry but you can now understand why it's imperative that we strive to post accurate information that can't be misconstrued by our non English speaking members, the chemicals and many of the processes we discuss have many dangers and none of us wants anyone hurt or worse.


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## richardbal (Jan 17, 2012)

hi Nickvc
yes is true every one must be carefull ??? what we are talking about on here is dangerous i agree to 100 %.
thanks for all advices and let me say that, this forum is verry important for all .so let we keep it as clear as possible
thanks guys
richard


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## goldsilverpro (Jan 17, 2012)

richardbal,

The presence of chromium in the cemented silver is a puzzle. I see only 2 possible sources for chromium.

(1) Some of the parts you are stripping are chrome plated and not silver plated. They could look very similar.

(2) The base metal is stainless steel, which contains chromium.

In either case, you could dissolve some chromium with the acids. I have no exact idea how it would end up with the silver but I do know that silver chromate is not soluble in acids.

As I understand it by your description, you are not running an electrolytic cell. It seems you are using the 95% H2SO4/5% HNO3 solution at 180F that is described in all plating books for stripping faulty silver plate from copper or copper alloy base metal, so the parts can be replated. The solution is not designed to be used on stainless steel or other non-copper alloys. There are better ways to do that but most involve cyanide.


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## adam_mizer (May 7, 2012)

Good thread, told me my answer on silver conversion.
Using chloride method ph >12 lye. PH 8 sugar.

I went wrong on the sugar and it didn't take much.
Adding sugar mixing and stirring until turns to silver metal.
There was a point that the silver metalized on the sides of the glass.
Is this the point of too much sugar, because I added another teaspoon and stirred and the silver metal on the sides came off.
But some silver converted back to oxide color or lighter brown.

My question is how to convert this back to silver metal?


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## goldenchild (May 8, 2012)

You simply add your sodium hydroxide in increments until all of your *clean* AgCl is totally converted. You have to be very thorough when doing this leaving as little non reduced chloride as possible. It is very easy to notice as the oxide should be dark gray to black and the chloride is of course white. Then you can add your kyro or sugar in increments until all of your oxide is totally converted. Also easy to see as metallic silver should be much lighter in color than the oxide. The mirror effect on the glass could simply have been from a dirty vessel. It’s not a big deal. You can sometimes observe the same thing when dropping gold with smb(gold mirror). I don't believe you can add too much kyro or sugar but you can add too much sodium hydroxide.

A little gem told to me by Oz. Everyone knows that silver can be put into solution by acidic dissolution but not many know it can be put into solution with base. If you suspect you've added too much sodium hydroxide you can check by simply adding some HCL which will convert back to AgCl. If you add everything in increments you shouldn't have any problems with this.

Here is a vid of the entire process if you haven't already seen it. 
Shameless plug in

3

2

[youtube]http://www.youtube.com/watch?v=xM-YsiFnJ1I&feature=plcp[/youtube]


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## adam_mizer (May 8, 2012)

Thanks Mario,
The video was very good.

Will have to figure out or purchase the flux complex.
Have mostly silver metal and was able to pour off the oxide with many washes.
I let this oxide settle several days. 
There is still some oxide in my silver metal, so I will have to use a flux I suppose.

Just dropped another round of chloride, I like using rock salt boiled in water. Works great per Steves video.
Like on my last round you can tell when all the chloride has changed to oxide. All the white is gone. I'm assuming this is the correct point to stop adding hydroxide.
Using pure cane sugar, everything was fine and color was changing but just at a point of 1 more teaspoon sugar all of a sudden from the gray color it quickly changed to brown.
Oxide is dark brown and black, I'm seeing mostly dark brown in my oxide.
This point of the 1 added teaspoon of sugar is where it went wrong. You are telling me that its not the sugar but the hydroxide.
So at the point the last white chloride converts is where I stopped adding NaoH, was that correct?

Personally there was a fine line on the sugar addition in my reaction. The PH balance was incorrect.


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## butcher (May 9, 2012)

Adding some carbon source to the oxide will help convert metal-oxides to elemental metal in the melt and make CO2 gas in the process, charcoal, or flour or some other carbon source would work, if it was not much oxides you could just add more fuel and less oxygen to the torch and convert some oxide using an reducing flame from your torch.


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## goldenchild (May 9, 2012)

For the purpose of my answer I want to make sure you understand exactly what I’m referring to so...
liquor = the liquid left after dissolving the silver in nitric

chloride = the white fluffy cottage cheese material produced when adding salt to the liquor

oxide = the black material left after reducing the chloride with sodium hydroxide



adam_mizer said:


> Will have to figure out or purchase the flux complex.
> Have mostly silver metal and was able to pour off the oxide with many washes.



There is no special flux per say. I used that term because some people like to put additives in with their borax when melting. You would probably be successful in simply melting silver oxide in a well seasoned crucible. However, there was really no need to pour off the oxide. You could have just continued reducing the oxide until it was all elemental silver.



adam_mizer said:


> Using pure cane sugar, everything was fine and color was changing but just at a point of 1 more teaspoon sugar all of a sudden from the gray color it quickly changed to brown.
> Oxide is dark brown and black, I'm seeing mostly dark brown in my oxide.
> This point of the 1 added teaspoon of sugar is where it went wrong. You are telling me that its not the sugar but the hydroxide.
> So at the point the last white chloride converts is where I stopped adding NaoH, was that correct?
> ...



Did you process your material exactly like in the video? I ask this because I'm wondering if you left things behind or added things that were supposed to be taken out when processing. Its paramount that after you drop the chloride out of the liquor you rinse the chloride extremely well. Leaving any blue liquor in the chloride can interfere with the reactions. Especially in the conversion to oxide stage. Remember. If any of the blue liquor is left behind you would be dropping copper out of solution along with the silver oxide making your purity suffer.

After you dropped the chloride out of solution and converted it to oxide with sodium hydroxide did you leave the hydroxide liquid behind? If you poured the hydroxide liquid off I don’t think you can then convert to elemental silver. Never tried it before so I could be wrong. If you washed your chloride well I wouldn't worry about the liquid turning brown while adding sugar. I think this has to do with the extreme heat of the reaction and the sugar in solution. Some type of caramelizing possibly? I suspect either your rinsing was not as good as it could have been or the processing was done incorrectly. Correct me if I'm wrong.


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## adam_mizer (May 9, 2012)

Thanks Mario,
Yes the chloride was rinsed many times until clear because this is the point of purity in the wash.
However as clean as I would like to think I got the chloride it's quite possible some small amount of copper may have been left, but when the chloride wash is clear a person would think they completed this rinse cycle.
Not just 1, 2, or 3 rinses but double that to 6 or more rinses easily.
When I added the sugar at the point of steam I allowed a 5 minute cool off before adding more. Maybe I just didn't allow the solution to heat enough?
(My very first solution last year, I had added the sugar too fast and got a boil over mess). I fear this again! 

I'm doing a smaller batch this time and will see the result.
Hopefully there's nothing else in the bag of sugar! It states pure cane sugar granulated fine.

So maybe just using sodium carbonate with the silver powder in my borax prepared melt dish hopefully should convert the final oxide.

Now the beaker used to catch the oxide brown color, now after 4 days has settled quite a bit. I will clean it out and dry it. Melt by itself.

Mario I did this per Steve's DVD video. Have a feeling I just goofed at the sugar part being scared of too much heat. Makes me wonder if I used enough sugar now. 
This next one I'll test with litmus and get it very close. Also I'll allow more heat and not allow it to cool off as I did.


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## adam_mizer (May 10, 2012)

You know I might be too critical of myself.
Several days have passed and the floating brown particulate settled and when I poured off the brown liquid I had very fine gray.
Funny how the liquid appears to change the color of the particulate, and when its poured off you see something completely different.
I worry too much about messing up and maybe take it very very slow.
This has happened to me before.
Will just have to be more patient waiting for the stuff to settle, and start getting used to the colors I see.

How important is it to rinse with hot water?
This might be something I'm missing.
Does it speed the cleaning and rinse up?


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## Harold_V (May 11, 2012)

adam_mizer said:


> How important is it to rinse with hot water?


Are you asking about washing precipitated gold? If so, and please understand that this is only my opinion. Not important at all. In fact, I'd avoid doing it entirely if the gold was slow to settle. There's not much gain, if any, and you add hours of time to the washing process (because you put the fine gold back in suspension and it doesn't settle quickly). You'd be far better served by simply starting off with a boiling wash with HCl. That often causes the gold to agglomerate, so it will settle quickly, assuming it does go in to suspension. Follow that wash with a boiling rinse, then do a boiling wash with ammonium hydroxide, a boiling water rinse, then another boiling HCl wash and rinse. If the gold is still of questionable quality, a second refining will do wonders. 

Harold


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## goldenchild (May 11, 2012)

We're talkin' silver here Harold :lol:


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## Harold_V (May 12, 2012)

goldenchild said:


> We're talkin' silver here Harold :lol:


Sigh!

Trust me to get it wrong.

Thanks, goldenchild. 8) 

Hot water can be useful in removing lead nitrate. 

Harold


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## adam_mizer (May 13, 2012)

Looks like its coming along.
Sometimes I just need to see some obvious colors and reactions.
Mario the video was excellent, between yours and Steve's all went well.
I just ended up with some silver in suspension, after filtered it was torched into a small button with sodium carbonate mixed in.

Here's a couple pictures.
Almost clean, had a few more rinses to go.
Cleaned and dryed silver. EDIT! forgot to add converted.
Next run 400g material to start.

Lessons are being learned.
Thanks for the help the video goes a long way with the visual.


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## goldenchild (May 13, 2012)

You have the same exact hotplate I use but in much better condition :lol: This hotplate should last you close to forever. Show us your bars when you're done :!: 8)


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## adam_mizer (May 29, 2012)

I'm not done but did make 12 bars.

Trying to learn from this I noticed if I added in the sodium carbonate, mixed a little, then heated the silver powder until melted and heated still for another minute it was better.
Then preparing mold, clean, preheat and pour. Its not easy!
I have some oxides on the surfaces.
Well I'm not super happy but can live with these bars.
Only way to get this better I think is to process in the silver cell.
Well here's the pics top and bottom.


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## amesametrita (Oct 21, 2012)

4metals said:


> If you have the proportions of sodium hydroxide and sugar correct the conversion should be complete, however mixing is critical and a lack of it usually causes the chlorides to clump and not react completely.
> 
> I have 1 client who reacts the silver nitrate solution coming out of his silver cells daily with HCl to form silver chloride. This is filtered and rinsed well and water is added to slurry the chlorides. The copper concentration in the water is checked with copper test papers and if found to be below 10 PPM the process of adding caustic and and sugar begins. If the copper is below 10 PPM the silver dropped will assay in excess of .999 fine.
> 
> I know GSP will be reading this and be thinking why go to the chloride step when cementing with copper yields .99 and perfect feed-stock for your silver cell. In this clients case, we're talking about solution running 80 grams silver per liter and we're changing 1200 liters per day. That translates into 3000 ounces of silver which is either marketable as .999 directly after treatment, or finely divided enough to be easily digested and upgraded chemically to .9999 and sold at a premium.



Dear 4metals,

What kind of reactor vessels do they use?


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