Contaminants Not Dissolving

[Buildeddie97]

Hello All,

I've run into the issue of not being able to clean my silver chloride of all contaminants before I do the process of adding NaOH and sugar. I have an x-ray gun that shows some iron, copper, and some other metals occasionally. I washed the silver chloride many times with DI water and then proceeded to use HCl (50% HCl by volume) to clean it. After a day, I came back and there was still plenty of iron shavings floating around. I tried to use sulfuric acid and heating both of the acids but still no progress!

Am I using too high of a concentration? Has anyone found the "magic" number for the molarity of their acids? Should I try and use fresh nitric? Do I need to worry about iron contamination if I am mixing in NaOH?

Any help to these questions is highly appreciated!

Thanks,
Edward

 

[butcher]

Silver will not alloy with iron in a melt.
I would use ammonia to test the copper levels in the rinse solution. I would forget about using the xray gun on solutions.

Iron, sulfuric acid, silver chloride and heat could have converted your silver chloride to silver metal...

I do not understand why you wish to now try using nitric acid? Unless maybe to confirm a sample of the silver to determine if your dealing with silver chloride or metal silver.

Yes with some acids that are of different concentrations or molarity can react different to some metals, some metals will passivate in a concentrated acid and not dissolve, but then dissolve in a very dilute acidic solution.

At this point I would probably just use sulfuric and iron to convert the silver chloride to metal.

 

[Buildeddie97]

Butcher,

Thank you for the response. I was using the x-Ray gun on a dried sample of the silver chloride powder at the bottom of the beaker. The reason I wanted to add more nitric was to ensure any remaining metal ions were fully dissolved. There is a chance that some extra contamination happened from other processes and I would like the final silver purity to be above 99.9% which is why I am so hyperfocused on getting rid of all the contaminants.

As you saw my other post about the process taking a long time, the iron, sulfuric acid method was taking much too long. Even with heat and constant stirring, I wasn't getting much conversion. Do you know the exact numbers for the amount of iron and sulfuric acid to add?

 

[butcher]

Drying your silver chloride is your problem.
Making conversion extremely difficult.

Give details in one place, keeps the discussion or topic more simple and easier to follow in one thread, giving details, the better we understand what you are working with, and the results you see (that we cannot see), what you have done, the better we can understand the problem.

If that was my silver, at this point I would probably consider grinding it and fusing it with soda ash, and then smelting the silver.

 

[butcher]

Dry silver chloride
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjp1vOAicrvAhUgHzQIHYnpBt8QrAIoAHoECAQQAQ&url=https%3A%2F%2Fgoldrefiningforum.com%2FphpBB3%2Fviewtopic.php%3Ft%3D5773&usg=AOvVaw1vlR6M14PSUQ_2hc_Z0xMs

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjp1vOAicrvAhUgHzQIHYnpBt8QrAIoAXoECAQQAg&url=https%3A%2F%2Fgoldrefiningforum.com%2FphpBB3%2Fviewtopic.php%3Ft%3D22111&usg=AOvVaw1upi09IKMzH4cqxG4t0yKa

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjp1vOAicrvAhUgHzQIHYnpBt8QrAIoAnoECAQQAw&url=https%3A%2F%2Fgoldrefiningforum.com%2FphpBB3%2Fviewtopic.php%3Ft%3D7305&usg=AOvVaw2GTofUYeKdUhOCfwexN8g9

(If you have made silver sulfate then iron may help in a melt along with a little flux).

 

[Buildeddie97]

Butcher,

The majority of the silver chloride is still wet luckily! I only dried a tiny sample to analyze with the X-Ray gun for contamination so I don't think I have to worry about using the smelting conversion.

For the sulfuric and iron method, do you have any suggestions on exactly how much sulfuric acid to add, at what concentration, and at what temperature? I just want to make sure that I do it right the second time around.

 

[butcher]

Basically water with a little splash of sulfuric acid (say a 10% H2SO4 solution) or weaker is fine.

Clean iron No rust or oil.
Horse shoe nails or pieces of clean rebar...
I like taking the copper out of a small electric transformer, cutting the welds of the laminated iron, separating the laminated metal, incineration to burn off shellac and oils, brush clean and cut to strips.

Cover damp silver chloride with solution (the more solution or the more acidic water, the easier it is to stir and get the silver chloride to swim around iron) less solution will work, but may not be as easy to get the salt to come into contact with the iron, or by only converting the silver next to the bar of iron sitting in the pile of salt.

The reaction will work without heat but heating will help to speed the reaction and drive it forward.

You just do not want to boil off the solution thus converting your silver to sulfates, if you need more 10% acidic acid you can always add more to any you evaporate off.

Try a test tube full, to get acquainted before trying to skin the whole hog.