Some problems in my first experience ( Dissolve silver in nitric acid )

Gold Refining Forum

Help Support Gold Refining Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

saadat68

Well-known member
Joined
Aug 7, 2016
Messages
482
Hi
I had some problems in my first experience today.

1- I added slowly 1 liter nitric acid + 1 liter distilled water in some silver oxide batteries but after 2 minute acid fall out from erlenmeyer.
http://uupload.ir/files/oefs_bjklljhg.jpg

2- I see large volume of sludge in my solution. It covers my solution. Is this sludge normal ? ( I added some used filter papers to my solutions. Do they produce sludge?)

3- And major problem is NOx fumes. In videos in YouTube reactions complete in 20 or 30 minute. In my case I must add 2 liter acid to my batteries and I add 1 liter but after 8 hours I still see NOx fumes :shock: :shock: :shock:
Why ?
I add just 1 liter acid and some water and heat it. What is the problem ?
 
Did you wash the batteries with water first?
They have a basic electrolyte.

Did you add the entire litre of nitric? Small additions are much MUCH better..
 
Use a stainless 5 gallon pot. From the looks of it you had some iron cases mixed in with the powder. Did you screen it first to remove the metal case fragments? When you have iron like that and you don't add enough nitric acid in increments to keep the solution on the acid side, less than ph 7, iron will start to come out of solution and cause this mess. Once you start keep adding acid and don't stop until you are finished with the reaction.

Like Chris pointed out you also need at least two good washes to remove the zinc and the base which makes up the powder ( Potassium - Sodium hydroxide ).
 
Flasks and beakers are no good for this job if your going to do any volumes worth doing with batteries. Especially a flask since they form a restriction the further toward the top of the flask you get. It's like a volcano or a fire hose nozzle used to restrict liquid and boost pressure. You need room for the solution to expand. Your vessel needs at lest 3 times - 5 times the volume of your solution you plan to use. If you plan on using 1 gallon of solution, nitric and water, then you need a 3-5 gallon vessel.
 
Palladium said:
Flasks and beakers are no good for this job if your going to do any volumes worth doing with batteries. Especially a flask since they form a restriction the further toward the top of the flask you get. It's like a volcano or a fire hose nozzle used to restrict liquid and boost pressure. You need room for the solution to expand. Your vessel needs at lest 3 times - 5 times the volume of your solution you plan to use. If you plan on using 1 gallon of solution, nitric and water, then you need a 3-5 gallon vessel.
Thanks Topher_osAUrus and palladium
I washed them but not good! because it was my first experience

1- I don't remove the metal case fragments because I think silver oxides stick to them and I must separate them after acid leaching. Is it right ? How remove them? after milling with water?


2- If I use a pot for example 5 gallon pot, does it solve problem number 3

Thanks
 
I will get you some numbers from my notes when i get to my files in a little while at the shop.
When you have washed them right to remove the base and when they are screened to remove metal fragments it takes very little nitric to dissolve a lot of powder believe it or not. If you don't do these steps it will take a wholeeee lot more nitric than needed. It's a very efficient process when done right.

After you wash the batteries in a 5 gallon container with hot water pour the wash water with the powder through a screen to catch any metal fragments. This will eliminate the dusty screening part to remove the fragments. You can use something a simple as fiberglass window screen stretched over a 5 gallon bucket to catch them. Once you have it screened and the silver powder and water is in a bucket let it settle for about 12-24 hours. Draw the excess water off the powder leaving very little water. You can use a hose to siphon it off. Rinse the 5 gallon bucket into your stainless 5 gallon pot and this is your starting solution with water already added.
 
saadat68 said:
2- If I use a pot for example 5 gallon pot, does it solve problem number 3

Thanks

No it will not solve the nox problem, But........ Removing the base and the metal fragments as well as the base ( Potassium ) will cut done on the amount of nitric used and by doing this you will cut down the nox by a factor of 2x -3x times.
 
Palladium said:
saadat68 said:
2- If I use a pot for example 5 gallon pot, does it solve problem number 3

Thanks

No it will not solve the nox problem, But........ Removing the base and the metal fragments as well as the base ( Potassium ) will cut done on the amount of nitric used and by doing this you will cut down the nox by a factor of 2x -3x times.
Ok got it
Thanks
And last question
After washing and screening how much acid do I need?
I know I must add 1 liter for 250 gram batteries but how much acid need for this way ? Because after screening they are just wet powder ( with excess of weight for water) and without cases
 
Are you going to be cementing this from solution with copper or are you going to be precipitating it from solution by using salt to make silver chloride?

Are you doing this in batches and then paying the customer on yield from that particular batch or are you buying the batteries for yourself and then processing them for yourself?
 
I want to cement with copper because I had read cementation is better
I want to refine them and produce silver ingot and then sell
 
When done right it will take about 1.5 ml per gram of materials.
672 ml per lb of dry, washed, and screened materials.

Since you are going to cement with copper you don't want excess nitric in solution. The best way to accomplish this is to not digest all the materials. Batteries is not one of those things where you can really say X amount of nitric per X amount of materials. You can get close, but it's still just a guess. For this the best thing is your experience and your eyes!

Add all of your materials except about a 1/2 lb to your pot with water. Add heat while adding acid in small amounts of around 500 ml and watching for the red gas. Wait about 15 minutes between additions while seeing how much red gas is coming off. Powders are fine and will go into solution real quick! When you add 500 ml and notice that the solution doesn't increase in bubbling or the red gas is not as thick as before stop adding nitric and add the 1/2 lb of materials you didn't add in the beginning. By adding this last amount of materials you will consume the last bit of remaining nitric making it a whole lot easier if you are cementing with copper. Heat for another hour on high and then turn off to cool. When you go to filter the solution you will notice materials left in the pot that didn't dissolve. Leave the materials in the pot while washing any solution out with water. The next batch you do will be added to the pot and the process starts over.
 
Thanks
So I need just 310 ml acid instead of 2.5 liter for 600 gram batteries that refined yesterday WOW :shock:
Today I thinked about other ways like participate silver chloride with sodium chloride
Maybe this way is better choice for batteries, We don't need distilled water in this way as we must wash batteries very much
But I read in an article recovery of silver in sodium chloride isn't high
What do you think ? Cement with copper is best for batteries ?
 
Cement with copper is the simplest way to recover silver metal from solution. But if you have a lot of excess Nitric acid, it will consume a lot of copper.

I haven't read the whole thread, so don't know if someone has already explicitly said this . . . start with smaller experiments until you know what you are doing and what to expect, pouring a liter of Nitric acid into a flask onto some material is . . . :shock: work with 50g of material until you have your process figured out.
 
saadat68 said:
Thanks
So I need just 310 ml acid instead of 2.5 liter for 600 gram batteries that refined yesterday WOW :shock:
Today I thinked about other ways like participate silver chloride with sodium chloride
Maybe this way is better choice for batteries, We don't need distilled water in this way as we must wash batteries very much
But I read in an article recovery of silver in sodium chloride isn't high
What do you think ? Cement with copper is best for batteries ?

Are you talking about whole batteries or just the powder from the batteries?
If you had 600 grams of powder it would require 900 ml of 67-69 % nitric acid.
600 grams X 1.5 ml = 900 ml

Silver chloride on a small scale is easy, but on a larger scale is rather difficult if your not set up for it in your lab. It requires a conversion process that will add a lot of waste to your stream.
I would stick with copper cementing and set up a simple silver sell because it is more forgiving if your not experienced with the chloride conversion or don't have the right equipment. Unless your water is ridiculously high in chlorine you can use city tap water. The small amount of chlorides produced is very little silver loss and won't interfere with either process. Now for a silver cell you want distilled water!
 
I had 600 gram batteries and used 2400 ml 57% nitric acid
If I washed and screened them I had max 210 gram (0.46 lb ) dry powder that need just 309 ml acid :)

Can I wash them with tap water or use tap water for leaching and cementation and then remove chlorine with silver cell and then melt silvers
Or Do I must use distilled water in all of process

I must search in forum about this but now I must go to workshop
 
I don't want loss silver or make problems in melting. My problem is just washing batteries.
What happen if I wash them with tap water and let to dry and then leach with acid and distilled water ( then go for cement and melting ) ?
In this way do I lost any silver or produce silver chloride ? If yes how much?
 
Are you trying to produce silver to sell to consumers ( general public ) or are you trying to produce a clean product to sell to a refinery?
 
Hi
Can I use coffee filter instead of filter paper for filtering Silver Nitrate solution?
I have sheet filter paper and I don't know what is it's size and brand. After 3 days I filter just half of 3 liter solution!!!
 
Sounds like you should have let it settle and siphoned off the clear solution, only filtering the last bit.
Sometimes thats just the best way to go about it.
 
Back
Top