Silver Oxide Batteries

[MikeyB3649]

Hello, let me start by introducing myself.

My name is Michael Henderson and I live in Hesperia, CA. I have been doing research for the last few months on how to covert silver oxide batteries into elemental silver. Today, I came across this site and have spent the afternoon trying to develop a process. I came across Manuels post which, in addition to the general reactions list, set me on a path I would like to pursue. I do, however, have some questions specific to my situation that I hope someone can answer.

1. I live in Southern California and have been unable to locate a source for nitric acid, HCl, NH4OH or NaOH. Can someone offer guidance on where I might be able to aquire some locally?

2. The cells that I have were from a military spec battery used on aircraft and are very large. The primary metals are silver and zinc. I have opened them and have found that they seem to be composed of a grid like mesh with a blackish sludge. I'm assuming this material is the silver oxide. Would this assumption be correct or is the grid the silver, not the paste? How would I go about checking?

3. I wanted to make sure that I have the process correct before proceeding.

Dissolve in nitric acid --> add common talbe salt to precipitate out the Ag and Hg --> filter and wash the white ppt --> add aqueous ammonia to the white ppt to remove the Hg --> filter the liquid --> add HCl to the liquid to reform AgCl --> add NaOH --> wash and add karo syrup --> wash and filter

Any help with all of this would be wonderful.

Thank you,
Michael Henderson

 

[publius]

My question is: Is there mercury (Hg) in silver oxide batteries.
Comment: There is an excellent post in the chemical section IIRC that offers several common chemicals that can be found in home repair/hardware stores that are exactly the same acid/base/salt that is required to begin your quest to recover silver. Also, before another member mentions it, download CM Holk's book that can be found in the signature line of many of the forum members here.

 

[qst42know]

Right on the package is a warning.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=3212&p=118896&hilit=mercury#p118896

 

[publius]

My question is: Is there mercury (Hg) in silver oxide batteries.
Comment: There is an excellent post in the chemical section IIRC that offers several common chemicals that can be found in home repair/hardware stores that are exactly the same acid/base/salt that is required to begin your quest to recover silver. Also, before another member mentions it, download CM Holk's book that can be found in the signature line of many of the forum members here.

That is enough to scare me away fron then...

 

[goldsilverpro]

I once refined a large military (or, space) silver oxide/zinc battery and got about 200 oz of silver. However, it's been 30 years and I don't remember the electrode arrangement or how I did it. It was the only one I have ever seen. I do have a book (Silver - Economics, Metallurgy, and Use, by Butts and Coxe) that devotes about 15 pages to these type batteries. According to this book:

There are secondary batteries and primary batteries. The secondary batteries are rechargeable but the primary batteries (one-shot) are not. Both electrodes of the secondary battery usually (but not always) consists of a solid silver expanded sheet grid. On the positive plates, a silver oxide coating is attached to the grid and, on the negative plate, a zinc coating is applied. The primary batteries are made the same but, in many cases, the grids are only silver plated copper. The electrolyte is potassium hydroxide so, use gloves and a face shield. Some sort of membrane separates the cells.

If you dismantle one of these batteries, keep the positive and negative plates separate, since they will be treated differently.

If the positive plates have a solid silver grid, they could be rinsed, dried, and then simply melted in a crucible furnace with a little borax. The silver oxide coating will convert to silver metal by the heat. If the grid on the positive plates are silver plated copper, I would probably rinse them well and then dissolve the grid and silver oxide in nitric and cement out the silver.

On the negative plates, the coating is zinc, but the grid could be solid silver. After rinsing, you could probably dissolve away the zinc with dilute H2SO4 and then melt the grid. If the negative grids are silver plated copper, the negative plates would essentially have no value.

You can test the grids by applying a couple of drops of a 50/50 solution of nitric acid and observing the color after about a minute. If silver plated copper, you will get a blue color.

Whatever you do, perfect your process with small quantities before tackling the whole battery.

 

[MikeyB3649]

I once refined a large military (or, space) silver oxide/zinc battery and got about 200 oz of silver. However, it's been 30 years and I don't remember the electrode arrangement. It was the only one I have ever seen. I do have a book (Silver - Economics, Metallurgy, and Use, by Butts and Coxe) that devotes about 15 pages to these type batteries. According to this book:

There are secondary batteries and primary batteries. The secondary batteries are rechargeable but the primary batteries are not. Both electrodes of the secondary battery usually (but not always) consists of a solid silver expanded sheet grid. On the positive plates, a silver oxide coating is attached to the grid and, on the negative plate, a zinc coating is applied. The primary batteries are made the same but, in many cases, the grids are only silver plated copper. The electrolyte is potassium hydroxide so, use gloves and a face shield. Some sort of membrane separates the cells.

This is precisely what I have. The battery came from an aircraft using Silver/Zinc batteries as a back power source. These are the secondary type and are rechargable. I have been able to get two of these batteries, a total of 32 cells weighing around 800 grams each. I suspected there would be a great deal of silver inside but haven't been able to figure out how to get the materials, or the exact process, to reclaim it. Does the process that I have described sound about right? I looked over the MSDS and didn't see any mention of mercury within the cells, but I'm going to err on the side of safety and assume there is.

Another thought that I've had is this. Since the electorlyte is potassium hydroxide, it would consume the costly nitric acid. If I do go about reclaiming the silver, would it be benificial to pre-wash these cells in HCl in order to neutralize the KOH?

I have also read through the silver section in CM Holk's book and it doesn't describe what I'm looking to take on. Would it be possible to get an exerpt or a link to buy the book you have that discuss them?

Goldsilverpro, I couldn't help but notice that you're from MO. If you're familiar with the company, these batteries were produced by Eagle Picher, if that provides any relevant information.

 

[goldsilverpro]

I would not use HCl or any other chloride in the process. This will likely produce some silver chloride and will complicate the silver recovery. I would just rinse the electrodes well with water before chemically treating them or melting them. A little remaining KOH won't consume much nitric. Also, any acid will dissolve silver oxide and HCl will probably convert it to AgCl. You don't want either of these things to happen. Just rinse as well as you can with water.

Reread my last post. I added some things.

I doubt if there's any mercury in these. At least, there's no mention of any in the book.

 

[MikeyB3649]

I would not use HCl or any other chloride in the process. This will likely produce some silver chloride and will complicate the silver recovery. I would just rinse the electrodes well with water before chemically treating them or melting them. A little remaining KOH won't consume much nitric. Also, any acid will dissolve silver oxide and HCl will probably convert it to AgCl. You don't want either of these things to happen. Just rinse as well as you can with water.

Reread my last post. I added some things.

I doubt if there's any mercury in these. At least, there's no mention of any in the book.

Ok. I reread the post. I'll go ahead and open them up, wash and rinse the positive plates and test a small corner to see if it's a solid silver grid or if it's copper plated and then repeat the test on the negative grid to determine what I'm working with on that side. If I have solid silver, I'll figure out a way to melt it down, probably just watch some videos on youtube to see about builidng a backyard furnace, and cast it into ingots. As for the silver oxide, there is a great deal of it on the grid. Would this still be alright to melt with the grid or do you think I should attempt to convert it to AgCl and then reclaim it that way?

For me, the hardest part is getting the nitric acid to test the grid. California is almost to the point that they want you to show ID just to buy dishsoap so I'm having a difficult time with that.

I'm very new to this with a basic background in organic chemistry so thank you SO much for your assitance.

 

[goldsilverpro]

I only create AgCl intentionally when it's absolutely necessary. In this case, I can't see it being necessary.

Check your messages (PM)

 

[MikeyB3649]

The H2SO4 is reactin with the ZnO, but very slowly. Can you suggest a method to speed up the reaction?