My New Silver Refinery - Thum Cell

[Glen Billeter]

Well I followed the process with fresh ore. Add Sulfuric and let work for
24 hrs. It was still showing bubbles and signs of working so I let it go another day. Cleaned and washed cons 6-7 times. Add water and then Nitric.
Nitric was working, lots of bubbles, but no red fumes. Let it sit and work for 24 hrs. Poured off in to bucket. Let settle and decanted washed 3-4 times. Had about 4 gals of solutions. Added new copper pipe. Pipe cleaned a little, but other than that,..... nothing. No bubbles. No fizzing. No activity at
all. Can anyone tell me what I've done wrong. I have 5 more buckets with
nitric working but I don't know if I should do the same thing. Any Ideas.

Thanks
Glen Billeter

 

[solar_plasma]

You want to know, how much silver there is in the ore, right? If so, then take one litre of the solution, add small amounts of HCl, stir, wait till the surface clears a bit, add a bit HCl again...do this until no more white silver chloride forms when adding HCl. Instead of HCl you can use NaCl, like Butcher already said.I just like to do it with HCl since I believe the reaction is faster and more precise, but it doesn't matter, what you take. You can even add an excess of chloride. Then let it sit some hours or a night and decant. Wash, dry, weigh and multiply the weight in gramm with 0,7526251526251526 and you know how much silver there is in one litre of your solution.

That IS the proper way of quantitive analysis of silver, - ask any chemist. It IS. This way you will find every single milligram of silver. Only 1,88 mg/l will stay dissolved in water. In acidic condition it may differ a bit, but also that could be calculated. I remember those lessons from highschool/college, I just hated it, when I was a pupil/student. If there is only a little silver compared to your gallons of solution, cementing will take maybe weeks, the silver will be unpure and you will not recover every milligram unless you brush your copper, then you will probably not only have cemented all non silver precious metals but also have some copper in it.

Cementing is for revovery. Precipitating Ag+ as its chloride is quantitive analysis.

 

[butcher]

Glen Billeter,
As you know the compounds of ore can be very complicated as to the chemical makeup of the ore and the metals involved, many of these ore's were formed from acids although there are some formed from an alkaline, since sulfide are probably the most common lets focus on them for a minute, if we tried to use this directly in acids we could have problems, not to mention some of the possible danger from the fumes (hydrogen sulfide gas or arsenic...), after concentration we need to take the finely crush the ore, and roast it to red hot in an oxygen rich environment, with good stirring this will improve our ore, convert metal sulfides to metal oxides, helping our later leaches to react with the metals in the ore.

The roasting can also help to remove chemicals in the ore that can act negatively with our leaching process.

The sulfuric acid would be good to get copper, and would not dissolve the gold, but if you are trying to leach silver I do not think I would use sulfuric acid, as it can make silver sulfates which are not very soluble, then if going to a nitric acid leach after wards you may have trouble converting the silver sulfate to a silver nitrate solution, without roasting the material again before using your nitric acid.

 

[Glen Billeter]

Thanks Butcher,

I think sometimes I get in to much of a hurry to get done.
After washing out the sulfuric, I didn't take the time to heat the material.
I will test a small amount tomorrow with hcl. If that works, can I add that
to my larger quantities of silver nitrates that I have. Just to make sure I
understand, by adding the hcl to the silver nitrate, the silver will drop out
and I can wash it and then melt to a button. Is this correct? I have some
liquid that is very dark,[almost black], dark blue to and very lite blue-green color. Will it work the same for all solution strength. Will there just be a
larger or smaller amout of silver.

Thank you

Glen Billeter

 

[solar_plasma]

No, the silver will drop as AgCl, white unsoluable powder. This has to be reduced first before melting. There are several ways, but as Alentia said, it's more work than cementing from silver nitrate. So, it's optimal for analysis. Cementing may be better for large quantities.

I would treat AgCl with NaOH to AgOH and NaCl, wash well and dissolve it in HNO3 to AgNO3, which I would add to the AgNO3 stock for cementing. Edit: But this I only would choose, because it is easiest to me. There are better methods.

 

[butcher]

Silver chloride will precipitate form a dirty solution of nitric acid and other metals, the silver chloride (most chlorides are soluble, silver being one of the exceptions), the silver chloride may drag down some other metals from the solution as if forms the curds, you may have to give the silver chloride a little more time to settle.

The silver chloride cannot be melted back to metal, as much of the silver chloride would be volatile, and just go up in the white smoke, the silver chloride needs to be converted back to metal before melting, there are several methods of converting the silver chloride, NaOH & Karo syrup, dilute sulfuric acid and iron, or aluminum and HCl, you can learn about these methods on the forum.

With a flux heavy in sodium carbonate it is possible to convert the silver chloride in the a melt, as you heat and then melt the silver, but I suggest you convert it to silver before melting.

Silver cemented from solution by using elemental copper metal, can be washed well, and then dried and directly melted, because the silver is cemented out of solution as elemental silver metal powder.

 

[solar_plasma]

One method from internet, I used my first time, I absolutely NOT advise: silverchloride, water, acid and pieces of zink in a bucket. I had that much AgCl left in my partly cementet silver, that when I tried to melt it, nearly 50% was blown off as smoke.

 

[Alentia]

Well I followed the process with fresh ore. Add Sulfuric and let work for
24 hrs. It was still showing bubbles and signs of working so I let it go another day. Cleaned and washed cons 6-7 times. Add water and then Nitric.
Nitric was working, lots of bubbles, but no red fumes. Let it sit and work for 24 hrs. Poured off in to bucket. Let settle and decanted washed 3-4 times. Had about 4 gals of solutions. Added new copper pipe. Pipe cleaned a little, but other than that,..... nothing. No bubbles. No fizzing. No activity at
all. Can anyone tell me what I've done wrong. I have 5 more buckets with
nitric working but I don't know if I should do the same thing. Any Ideas.

Thanks
Glen Billeter

Glen,

If nothing had cemented on copper, that would mean, no silver in the solution. Unless, there was not enough nitric and silver got cemented by other metals, right in the digestion bucket.

I had observed with ore, due to mutliple metals present (as butcher mentioned), brown gas is not always generated to digest silver, as it probably getting absorbed by something else in the ore.

 

[solar_plasma]

We talk about 1,5-6 g silver per kg ore dissolved in some gallons of acid. That ist not much for cementing, but much for chloride precipitation. As an example I remember my silver solder with 1% silver, rest Cu and Zn. I only dissolved some 100 mg in 20ml HNO3 and I got a visible chloride reaction with some drops HCl. I leave it to the reader's math to calculate how many mg of silver that was.

It could be that all the silver was bound as sulfides as butcher pointed to and I really don't know, if those would react fast enough with diluted acids, so it could very well be, like altentia said, that there is no silver in the solution, but still in the ore. If there is any, would one drop of HCl show.

 

[Glen Billeter]

Well, I took 1 liter of solution from 2 different samples. Both had almost
no action with the copper. I added hcl to each one , got nothing, I added more and got nothing. I added a total of 20 ml to each 1 liter test. no action at all. It looks like there is zero amount of silver in the solution. I believe you are correct that maybe the solution of nitric added was to diluted in material and the silver got cemented to other metals. I had the solution from my very first test so I decided to do the same test. I poured all the different bottles of solutions from my first test, into 1 large glass jar, about 4 liters. I started adding hcl and stiring. With in 1 min, a gray cloud of material started to drop to the bottom. I added more hcl and keep stiring. With in 5 mins I had 2 inches on the bottom and much more dropping. After about 1 hr I now have about 4 inches of heavy gray on the bottom. I'm going to assume that this is my silver. I will let it sit over night.
Question: Do I pour this through a filter or slowly pour off top liquid, leaving sludge on the bottom, let it dry and weight.

Thanks to everyone for your comments and directions.

Glen Billeter

 

[solar_plasma]

Let it clear, decant the top liquid off, fill up with destilled water, stir, let it clear - at least 3 times. Then again decant off the clear liquid and wash the powder down in a filter - coffee filter will do it. Then dry and weigh. If there is lead in the ore the washings should be done with hot water.

I guess this procedure works with some kg or maybe some hundred, but :lol: I am sure, that way you don't want to extract the silver from your whole mountain of ore - you need to hire an expert to find and set up the best process for it. I don't know anything about ores, but I guess it will be some kind of leaching to do it big style.

... or you send one ton ore to each one of us and you get half of the silver back :lol: *just joking*

 

[g_axelsson]

If you want to process your silver chloride with NaOH and caros syrup then you should NOT let your silver chloride dry up.

The method of converting silver chloride into metallic silver with NaOH and caros syrup is discussed in many places on the forum. I guess there is also a link to the topic in the forum guided tour.

Göran

 

[skippy]

Nitric acid dissolves lead, but adding sulfuric acid will precipitate it as lead (ii) sulfate and adding hydrochloric will precipitate it as lead (ii) chloride. So if you dissolved your ore with nitric and then added HCl you would get lead (ii) chloride as well as silver. Silver sulfate is slightly soluble, so carefully adding small doses of sulfuric acid with *lots* of stirring may allow you to precipitate lead first. The volume of chlorides precipitated makes me think you have a lot of lead in there.

 

[Alentia]

Glen,

Do not dry (seems)grey/white powder. Lead chloride and sulfate should be easily soluble in hot/boiling water, while silver chloride will not.

Since you get to the chloride, you have to wash it (preferably in hot water) until solution is clear (no blue color), do not filter, decant only.

When wash is done, add water about the same amount of chloride and drop piece of iron in it, add H2SO4 about 1/10 of water and let it sit there for a day stirring occasionally. White precipitate should be converted into grey cement/big flakes/crumbs. If white small flakes still left around add about 1/10 of H2SO4 and stir. You can repeat the above until no white flakes left at the bottom or floating around. Discard solution and wash cement with hot water.

For the bucket where you get no silver in the solution, wash sediment by decanting 3-4 times, when finished washing, add a bit of water (around 100ml or to cover) and bit (25ml) HNO3, stir and observe if there is a reaction after about 10-15 min.

 

[solar_plasma]

Yeah sure, if your main goal is to reduce and melt it, don't dry. Dry only, if you only , precise and fast as possible, want to know, how much silver it is. But in the last step - melting and casting - you will probably have losses again. So that isn't quantitive anymore. You want to measure, how much silver there is, you don't want to measure how much silver YOU with your set and setting, your skills and this method get out of it. Makes no sense to me. I guess you want to get comparable, validated measured values. You have to know, if you are measuring exactly what you want to measure and not some correlating phenomenons, side effects, artifacts and inaccuracies.

Sorry, but I feel like being home, when we talk sampling and measuring - keep the system simple.

So, both ways are ok. It depends on what exactly you want.

 

[kjt124]

This method of dilute H2SO4 and iron sounds like it is a heck of a lot easier and cleaner for converting AgCl than the NaOH and Karo... If you don't really have any access to the iron laminant sheets from transformers (as has been discussed before as a good source of clean iron), would the additional carbon in pig iron pose any problems? Or perhaps would a mild steel be a viable option? Perhaps I am just looking with the wrong eyes, but I am not having much luck finding relatively pure iron.

Thanks,
Kevin

 

[butcher]

Kevin,
Fairly pure iron is very rare nowadays, most everything nowadays is made from steel, I have used concrete re-bar to convert silver chloride in dilute sulfuric acid, it worked well.

Glen,
I am not sure how much understanding you have of these metals and acids, but a good way to learn is with small experiments, get you some old scrap sterling silver, and do some small experiments, with this metal, these experiments, doing this can give you a better understanding of what to expect, of course the reactions will be a little different with these more pure solutions, than when these metals are in your ore, a few experiments could be done with a little bit of silver added to the ore sample , experiment run to see if you recover more than the added silver or lose silver from the chemistry of the ore.

 

[kjt124]

Thanks butcher. I'll play around with it a bit.

Kevin