My New Silver Refinery - Thum Cell

[Dawg]

I'm interested on how your melt goes I had a similar issue several months ago with a batch I did, I ended up having to buy all new melting dish's had a nasty mess I did get everything fully processed had to do it twice though

 

[rybak97]

Did you use tap water to make the solution? If you did then the cloudiness could be silver chloride.

Also, I was using Dudadiesel Nitric 67.2%. The distilled water came from Wal-Mart. Maybe the Nitric was low quality? Does Wal-Mart sell bad distilled water? I don’t know which variable to change first.

If it is silver chloride, will that affect the purity of the silver?

 

[rybak97]

I'm interested on how your melt goes I had a similar issue several months ago with a batch I did, I ended up having to buy all new melting dish's had a nasty mess I did get everything fully processed had to do it twice though

What about the items in this thread makes you worried about the melt??? Why did you have to buy new melting dishes and what was a nasty mess?

 

[metatp]

Brian,

I think it is important that the silver you use to make your electrolyte is as pure as possible. I would use the crystal you make with this run to make your next electrolyte. Even when I use the crystals, I still filter it encase something fell in there. BTW, I don't use copper in the electrolyte, and it seems to work best for me. The cemented stuff I use for anodes have a little copper (about 1%) already in it.

Tom

 

[Palladium]

I've learned that the cloudiness only shows up for me from chlorides. Not saying that could or couldn't be your problem. Chlorides can not only be introduced from the water. anything you have used or touched that has any chlorides in it will carry over if you touch the silver nitrate solution with it. Filtering apparatuses, beakers, stir rods, anything that might have residue! It doesn't take much to make chlorides that cloud your solution. Good news is though that if it's just a little bit and you keep running then it will clear itself up. Shouldn't hurt anything. I can't give you the science but it's never affected my purity to the amount that i can tell it. Now that grey and black you speak of is a different story. The screw you have in the top of that don't look stainless to me. How do you know it's (real) stainless?

 

[rybak97]

How do you know it's (real) stainless?

It was advertised as stainless steel deck screws, and it throws sparks when I hit it with a grinder. However, I just hit it with a rare earth magnet and it is slightly magnetic. It must be ferritic stainless. Is that a bad thing?

It looks weird because I heated it to red hot before using it to burn off any coatings or oils that might have been there.

 

[Palladium]

Did you use tap water to make the solution? If you did then the cloudiness could be silver chloride.

Also, I was using Dudadiesel Nitric 67.2%. The distilled water came from Wal-Mart. Maybe the Nitric was low quality? Does Wal-Mart sell bad distilled water? I don’t know which variable to change first.

If it is silver chloride, will that affect the purity of the silver?

I buy my nitric from the same chemical supplier as Duda does and i use wal-mart water to so i don't see that as a problem.

 

[rybak97]

Did you use tap water to make the solution? If you did then the cloudiness could be silver chloride.

Also, I was using Dudadiesel Nitric 67.2%. The distilled water came from Wal-Mart. Maybe the Nitric was low quality? Does Wal-Mart sell bad distilled water? I don’t know which variable to change first.

If it is silver chloride, will that affect the purity of the silver?

I buy my nitric from the same chemical supplier as Duda does and i use wal-mart water to so i don't see that as a problem.

Maybe it was a dirty bucket? Next time ill use all new and cleaned equipment to remove that variable.

 

[metatp]

How do you know it's (real) stainless?

It was advertised as stainless steel deck screws, and it throws sparks when I hit it with a grinder. However, I just hit it with a rare earth magnet and it is slightly magnetic. It must be ferritic stainless. Is that a bad thing?

It looks weird because I heated it to red hot before using it to burn off any coatings or oils that might have been there.

I would definitely stay away from that screw. If something isn't marked, I first check it with a magnet, and then I would try it in some nitric.

I only had cloudiness once early on in my cell experience. I used that batch for my future batches of electrolyte, and it worked out great.

Tom

 

[mikeinkaty]

I've learned that the cloudiness only shows up for me from chlorides. Not saying that could or couldn't be your problem. Chlorides can not only be introduced from the water. anything you have used or touched that has any chlorides in it will carry over if you touch the silver nitrate solution with it. Filtering apparatuses, beakers, stir rods, anything that might have residue! It doesn't take much to make chlorides that cloud your solution. Good news is though that if it's just a little bit and you keep running then it will clear itself up. Shouldn't hurt anything. I can't give you the science but it's never affected my purity to the amount that i can tell it. Now that grey and black you speak of is a different story. The screw you have in the top of that don't look stainless to me. How do you know it's (real) stainless?

I learned that the hard way just a few days ago. I had filtered some silver chloride with my buchner funnel and forgot to wash it out when done. Couple of days later I used the funnel to rinse some crystals and the water was coming out milky. WTH!! The silver chloride had dried and caked inside the funnel. I had to wash the heck out to get it all out of there! I also accidentally picked up some Spring Water at a store the other day instead of distilled water. I caught that immediately when rinsing something (forget what). But the rinse water was running a funny cloudy color from it too. I did get 2.3 ozt silver from the silver chloride that I found caked up in the bottom of a 5 gallon bucket. That silver looked to be pretty pure.

 

[g_axelsson]

Chlorides can not only be introduced from the water. anything you have used or touched that has any chlorides in it will carry over if you touch the silver nitrate solution with it. Filtering apparatuses, beakers, stir rods, anything that might have residue! It doesn't take much to make chlorides that cloud your solution.

That is really true. I have a beaker with some silver in and when I get some excess nitric I pour it into that beaker, it kills the acid and I get silver nitrate from it. When I have enough I run that batch to finish and cement the silver with copper.
Anyhow, one day I put a beaker with HCl next to it. A couple of days later I discovered that the silver nitrate were covered with a pale purple surface, the HCl had evaporated from one beaker and reacted with the silver nitrate on the surface of the other beaker... and this was even standing outside on a table. :shock:

The lesson, keep your HCl away from your silver, it can spread even through air.

Göran

 

[rybak97]

Going backwards through the steps I used I’ve come to the conclusion that the water I used in the hot water bath caused the introduction of Cl. I was using a SS vessel over flame to heat a water bath where my beaker and watch glass were partially submerged.

The water I used in the SS vessel was from the tap. I think the evaporating tap water combined with the condensate on the watch glass and dripped into my reaction vessel. Since I was doing this outside, in the sun, it caused the chloride to turn purple and made my solution very cloudy.

Since this first run I've started using dark reaction vessels and no heat, I’m just patient and let the Nitric do its thing all night. This last batch was crystal clear and as blue as the Keys.

 

[mikeinkaty]

Since this first run I've started using dark reaction vessels and no heat, I’m just patient and let the Nitric do its thing all night. This last batch was crystal clear and as blue as the Keys.

Someone here told me to not heat a AgNO3 solution so I quit doing it and must say that I have not seen a real need for it when digesting silver with HNO3. No explaination was given as to why not. Like you I do my reactions outside and usually start them early enough in the day so that I have time to add the 2nd batch of acid before turning in at night. By the next morning it's usually done. I throw in a spare piece of sterling at that time to see if the acid has quit reacting. After about 1 hour if no visible signs of a reaction exists I prepare for the copper drop. I use quart canning jars and find it convenient to do 10 ozt sterling at a time.

Mike

 

[Dawg]

Rybak: I had a redish Brown Slag that would not melt I was using a MAPP torch

 

[Alentia]

I didn’t even realize that it was so important to use pure "ingredients" for the electrolyte. For it I used some of the silver shot I made from the cementation, but I also tossed in some of the fine powder I found at the bottom of the cementation vessel that I couldn’t filter. Perhaps it wasn’t silver? What do you think?

Cementation at best produces 98% silver with 2% of any crap possible.

That exactly where your problem with cloudiness lies. Electrolyte should be prepared with 999 silver and copper. I normally use sterling silver previously boiled and washed with NaOH.

They call it: garbage in - garbage out.

 

[Glen Billeter]

Hello to all.

Brian, excellent job of showing how it's working for you. This is my first day
on this site and I am amazed with all the good information you guy's are providing for rockies like myself. [Hoping to be a pro one day].

I have been trying to figure out the best way to find the value of silver in a
yard of sand and gravel. A friend of mine gave me his copy of Hoke's book.
I have been reading and trying to understand and remember the different
processes for silver and gold.

After concentrating I took the final material and extracted as much free gold
as I could. After that I ran all rock and gravel through a rock grinder down to nano size 100 mess and up to -12 mess . Then I took the concentrate and put in large glass jar. I add 70% Nitric and covered material by approximately 1". I did use regular tap water and diluted solution. My friend said that was ok. I started to get the red smoke and a lot of bubbles and increased temp. I let this sit over night.

The next day I proceeded to filter liqued through coffee filters. This is a
very slow process, having to change filters 6 or 7 times. In my filters I thought I would have a lot more sludge, which I was told held all the silver. This material doesn't have any silver if I understand correctly now.
In the container I have a nice blue liqued. I added copper tubing to the solution and watched it start bubbling. This totally consumed the copper tubing I had added.Now I have poured that liqued through coffee filters. I saved all the filters with the sludge. I am going to burn of all paper
and sludge and hope that I have some silver.

The question is: what do I do from here. Does the blue liqued hold any silver . Is making a Thum cell the best way to fixthis problem and extract the silver. We drilled 57 holes and took over 600 samples. Assay came back with 50 to 200 oz of silver per ton.
I don't know if I believe those results, so I'm going to do my own tests.

Thank you if any one can help.

Glen Billeter
Gold Rush Alaska
Fine Gold Recovery Specialist

[email protected]

 

[Palladium]

Welcome to the forum Glen. I'm not much of one for extraction from ores so i can't help you there. I can tell you that if your silver is in the nitric acid in solution and you added copper and it eat it up while producing red smoke that you have to much active nitric acid for the silver to drop. It will drop and then redissolve back into the solution the whole time eating up copper until all the free nitric is used up. Then the silver will start to drop. Did you roast the material?

 

[Palladium]

Oh cool ! I just realized who you are sir. Welcome on board !

 

[solar_plasma]

I am a bit unsure, if I should post this now, since you guys are pro's (and palladium is one of the silver refining gods), but if I have understood the problem right, some of your questions are fairly easy to answer: After dissolving in nitric acid your silver should not be in the filter sludge, but dissolved in the filtrate. Have you tried to precipitate a sample of the clear blue filtrate with HCl to form unsoluable white AgCl? This will also precipitate from acidic solution.

Until the pro's answer, here's a first hint: The cells in this thread are used for refining, not for recovering. To recover from AgNO3 containing solution the silver mostly will be precipitated or cemented, then (if pure enough) melted and used as a cathode in a cell in order to refine it.

 

[butcher]

solar_plasma, is correct,
You can test a small sample of the copper nitrate (after you cemented silver with copper) using HCl or table salt NaCl, if you have silver in the blue solution, you will see a milky white reaction if enough silver is left in solution you will see a white curds of precipitate of silver chloride.

Grinding, gravity, or some other means of concentration of the ore, and roasting of the concentrates is important for any leaching of ore, but I know even if I had an ore rich with silver, nitric acid would cost me more than I could make from any silver recovered, with the price of fuel today I do not know I would do any better smelting the ore.

If silver is dissolved into the nitric acid leach another method beside copper to cement it out of solution could be electrolysis (or the silver chloride method with salt above), with electrolysis you would need a graphite inert anode, and stainless steel cathode to recover the silver, this method would also push out other metals in the solution out of the electrolyte along with the silver onto the cathode, if they were involved in the ore (such as copper...)

Also you may want to do small assays on samples before and after an extraction or leaching process, example depending on what type of material or ore you are working with you may find that after you gravity separating your gold (black river sand for example) you may find most of the silver was actually in the gold you removed by gravity, and very little was left in the remaining iron ore.