Cadmium Presence in Sterling Silver

[mattafc]

I was having a chat today with a large European commercial refiner and we were talking about melting silver. One of the things that came up was the potential for up to about Cadmium of levels of up to 5% being present in most tableware. Having refelcted on our conversation I have looked at the precuations that should be taken when melting this material but am thinking about the alternatives. What I'd like to try to understand is: -

1. Is there any way to test items before melting to see if there is a Cadmium element to the items. Would XRF pick this up?

2. What would be the alternative to melting. I understand there is a chemical process but would this just move the problem to safe disposal of the chemicals?

Any help greatly appreciated.

 

[Fournines]

I was having a chat today with a large European commercial refiner and we were talking about melting silver. One of the things that came up was the potential for up to about Cadmium of levels of up to 5% being present in most tableware. Having refelcted on our conversation I have looked at the precuations that should be taken when melting this material but am thinking about the alternatives. What I'd like to try to understand is: -

1. Is there any way to test items before melting to see if there is a Cadmium element to the items. Would XRF pick this up?

2. What would be the alternative to melting. I understand there is a chemical process but would this just move the problem to safe disposal of the chemicals?

Any help greatly appreciated.

XRF should show you Cadmium, if it is set up to do so.

I've never heard of 5% cadmium in silverware. A lot of refineries I know won't touch anything with more than 1-2% cadmium - and even that's pushing it.

 

[mattafc]

XRF should show you Cadmium, if it is set up to do so.

I've never heard of 5% cadmium in silverware. A lot of refineries I know won't touch anything with more than 1-2% cadmium - and even that's pushing it.

Thanks, the refiner I spoke to told me they chemically treat anything thats over 0.2% Cadmium. What levels of Cadmium would you expect in Silver Tableware generally?

 

[nickvc]

From what I can recall from my time at JM the cadmium was only used in the spinning alloys they produced so flatware should be ok. I gather that some Indian made silver jewellery can have cadmium in but whether that's from the solder they use or from the alloy I'm not sure.

 

[mattafc]

Thanks Nick, thats useful to know

 

[peter i]

Cadmium is (was) added to increase malleability.

Furthermore it is used in contacts:

The alloying of silver with cadmium produces materials with good arc extinction, good corrosion resistance and low contact resistance characteristics and provides them with good switching capability in AC circuits. They have low transfer characteristics in some DC applications. The alloying increases the strength and hardness, but substantially reduces the thermal and electrical conductivity and thus limits their current handling capability. The silver-cadmium alloy contacts are ductile materials and can be supplied in shapes and sizes similar to fine silver.

ELKONIUM® 217 alloy has good arc interruption and anti-welding characteristics and has been used in line starters, solenoid contactors, automotive starters and other power switching applications for many years. However, more recently it has been replaced with the higher conductivity silver-cadmium oxide alloys of CMW D54F, D55F, D54X and D55X.

http://www.matweb.com/search/datasheettext.aspx?matguid=f64629f63b5d4f64acdad6bbca50a9e5

It is also used in silver solder to decrease the melting point.

I've never seen noticeable amounts of cadmium in the alloys I've submitted to XRF.

 

[hinv]

Forgive the newbie question, but what is XRF?

 

[jimdoc]

Forgive the newbie question, but what is XRF?

http://en.wikipedia.org/wiki/X-ray_fluorescence