Processing waste from silver chloride conversion.

[SerialHobbiest]

I’m studying and preparing to do some small outdoor silver refining, using sulfuric acid to dissolve the silver material, using hot salt water to precipitate silver nitrate, then converting it to metallic silver using lye and sugar.

I’m putting emphasis on personal safety (face mask rated for chemical use, gloves, long sleeves and pants, familiarizing myself with the chemicals, water station, baking soda and vinegar,).

I’m also working out the environmental concerns before I start anything. I’ll be using the fume trap mentioned on page 42 of CM Hoke’s “refining bible” for my first attempts. I plan to have a stock pot using copper for the acidic wastes from the precipitation of the silver chloride, just in case there might be some recoverable gold. After that, the material will go into a waste bucket with iron or aluminum, the liquids will be raised to a high ph then neutralized and disposed of, the solids will go to our hazardous waste facility.

What I’m hung up on is dealing with the considerable waste from the lye and sugar procedures. I’m assuming it would likely be a good idea to let it settle to recover any silver that may still be in there, but I’m not sure where it should go after that.

I’m thinking it “should” be safe to put it into the waste treatment bucket, since I would be adding lye to it anyway to raise the ph, but I want to check with the experts first.

Is my thinking sound?

 

[butcher]

You meant to say precipitate silver chloride, from using salt on the silver sulfate solution (unless there are nitric acid or nitrate salts involved you did not mention).

What type of silver scrap and how much are you thinking about?

Hot concentrated sulfuric acid can be some awful nasty stuff, dangerous around water, or your skin.

Maybe if we knew more of what scrap you have we could suggest a safer method of recovery of the silver from the alloy.

Is there some reason you wish to make the silver chloride from the silver sulfate solution? The idea just seems to be going somewhat backward (in my mind), if you dissolve silver as a sulfate why not consider changing that into the metal instead of changing the silver into a chloride salt then back to metal...

If your goal was silver chloride from a fusion process I would suggest using some other process, like cornflake the silver and using a fusion process with ferric chloride, while still a dangerous process using heat, it would be somewhat safer for the hot concentrated sulfuric and all of its dangers. or even using electrolysis, or making some nitric acid and distilling it...

How much practice have you had heating acids in glassware or easily breakable containers? These hot acids or salts can become much more destructive to the human body.

CuSO4 + NaCl --> NaCl + CuSO4 (no reaction).
AgSO4 + 2NaCl --> AgCl + Na2SO4
silver sulfate and sodium chloride (table salt) give an insoluble salt of silver chloride and a more soluble salt of sodium sulfate along with other possible metal salts such as copper sulfate...

Silver chloride and glucose C6H12O6 (a carbon-based sugar) such as Karo syrup and using NaOH also called caustic soda or lye (sodium hydroxide):
2AgCl + 3NaOH + C6H12O6 --> 2Ag + Na-C6H11O7 + NaCl +2H2O
The result is silver metal (Ag) and a soluble salt solution of sodium chloride (NaCl) and sodium gluconates Na-C6H11O6 (a carbon-based waste), along with possibly any other drag down materials or impurities like say some copper chlorides, copper sulfates... I will normally treat my silver waste separately from my other waste, but there is no reason you could not add this to your normal or general waste stream.

I

 

[Martijn]

From reading your previous post you want to dissolve in nitric.
Adding salt or HCL to it would create silver chloride.

Instead, converting the silver nitrate into cemented silver with copper and running it through a silver cell would create considerable less waste.
Compared to washing the silver chloride several times before the lye sugar conversion and washing the converted silver clean again. Imo. Correct me if i'm wrong guys.

And apart from the nitric fumes, which can be controlled, less dangerous than hot sulphuric in a glass beaker. And stirring a solution with lye around.

And forget face masks. They are meant for cleaning spills and accidents where fumes can not be properly prevented, controlled, contained or scrubbed. The reasons are pointed out often here. Search cartridge and read the posts.

Martijn.

 

[SerialHobbiest]

Thank you for the responses!

I don’t have any scrap at the moment, but it will be sterling silver like flatware and jewelry. This will be a tandem hobby of refining and yard sale hunting.

I was considering the sulfuric acid method because the cost of nitric acid is pretty high. I’m not trying to make a profit, but I don’t have a lot of capital, so I’m trying to keep costs low. I’m not even considering buying equipment to do melts yet. I’m going to stack the powdered metal for the time being and I understand precipitation silver chloride and converting it makes a purer product than precipitating it out on copper.

Is nitric considerably safer? I don’t mind spending more if that’s the case. Recapturing and reusing it appeals to my skinflinty soul, too.

I don’t have a lot of experience with acids, but I worked as a brewer years ago, and we did use a weak acid for cleaning, but it was a self contained system. I also had to use insanely powerful caustic and hydrogen peroxide, plus the ten or fifteen other things that could kill you if you mis stepped. I learned to think twice and act once.

I would love to run a silver cell, but I’d have to do it in my house, and I’m not sure how safe that is.

 

[SerialHobbiest]

Some context- I’m rehabbing a knee injury, so I’ve plenty of time to think and plan. I’m not going to jump into this

 

[Shark]

Even dilute sulfuric and iron is less messy, less dangerous and less waste when converting silver chloride. I may be wrong here, but I think you can drop silver from sulfuric as metallic silver using copperas (iron sulfate) as well. Need to double check that as I have been reading on two subjects and may them confused.

You can run silver in poormans nitric (with a small amount of loss to sulfates) and cement to copper to get metal silver, with washing, will be ready for a cell. Saving the silver sulfate that can be converted back to metallic silver when you have enough to work with.

I am getting a little more silver later today and hope to be returning to working with a small silver cell again fairly soon.