Chemical Extract silver from power relays

[balasparks]

I want to extract the silver from the Ag/CdO composition which is present in the power relays......

if there any process available plzzz let me know

 

[Geo]

Cadmium is dangerous if you breath it or eat it. This is the most important thing to remember. You can safely work with it by being careful and cover your reactions, work in under good fume control and practice good hygiene. In a beaker, place the contacts to no more than one third the volume of the beaker. Add equal amounts of whatever concentration of nitric acid you have and distilled water 50/50 to one half the volume of the beaker. Let the reaction take place without heat until the reaction slows down and then place the beaker on medium heat to finish the reaction. Be patient. Allow the solution to completely finish the reaction. There are one of two reasons the reaction stops, either the acid is depleted or the silver has been dissolved. turn off the heat and allow everything to cool completely. Decant the solution into a clean beaker. examine the solids left behind. If there is solid metals, rinse with distilled water and add this to the next batch. If there is no metal left, use the solution to dissolve more silver until the acid is depleted or you can neutralize the excess acid and proceed from there. If there are tungsten/silver points in the mix, a yellow powder of tungsten oxide will form. It's a pain to filter so I suggest you let the solution settle completely and draw the clear solution off from the top down.

 

[Platdigger]

As per Geo. Now once you have the contacts in solution, if you cement to copper your cadmium should still be in solution.

 

[balasparks]

Thank you sir, For your wonderful reply...

again one doubt........
If i dissolve my job in Nitric acid,then cadmium also will dissolve with silver.If that is the case how can i extract silver seperately from the solution.....

 

[Topher_osAUrus]

Thank you sir, For your wonderful reply...

again one doubt........
If i dissolve my job in Nitric acid,then cadmium also will dissolve with silver.If that is the case how can i extract silver seperately from the solution.....

As per Geo. Now once you have the contacts in solution, if you cement to copper your cadmium should still be in solution.

 

[balasparks]

How to do that cementing by copper ?

I have to add Copper sulphate?

 

[4metals]

Cementing is done with metallic copper. Another option is to drop the silver with salt as silver chloride. Your material may contain lead so a hot water boil of the silver chloride will dissolve out any lead chloride leaving you with clean silver chloride.

The silver chloride can be reduced with liquid caustic and corn syrup. Methods for the reduction of the chloride are discussed on the forum, so just search for Karo as that is the brand of syrup used here in the US.

Given a choice, dropping with metallic copper would be the first choice.

 

[balasparks]

Metal in the sense, I have to add metallic copper in powdery form or a copper wire is good enough?

 

[4metals]

Powdered copper is by far the best but slabs of copper or heavy wire will suffice if you don't have a lot to process.

The trouble with copper slabs and wire is when it gets thin, pieces of copper slough off and mix with the cement silver lowering its purity. With powdered copper your reaction is very quick and you can develop your technique so you only add enough to do the job and produce a very high quality silver.

 

[balasparks]

Thank you sir.........

this will be really helpful for my process......

 

[kurtak]

Here is a detailed article I posted on cementing silver with copper

:arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=23441&p=247009&hilit=cementing#p246984

hope that helps

Edit to add; - read the hole thread

Kurt