Newbie Needs Help Big Time with Gold

[Anonymous]

Hi all,

I buy/sell equipment and recently refurbished three Niton XRF analyzers. One of them was set up for precious metals to include Au.

After receiving the XRF back from Niton I recalled that I had several trays of different types military connectors. I tested the gold connectors with the XRF and much to my surprise they all showed gold content.

Most of the connectors showed only 10%, but one type connector showed 40%.

I will concentrate on the 40% first. Here is the exact breakdown from the Niton XRF:

Pb 1.25
Au 40.07
Zn 4.72
Cu 21.29
Ni 31.62

I have 4400 of these type connectors which weigh .07 grams each when stripped from the wire/silicon. (i tried uploading photos but keep getting an error)

I went ahead and bought a mini-oven from Lasersteve and today broke out the torch and Borax.

This is my first attempt at anything like this and it didn't turn out as I had hoped.

The connector melted fine, but much to my surprise after checking the melted piece it showed no gold content any longer.

Here is what the new melted piece showed on the XRF:

Pb 6.72
Zn 28.77
Cu 59.33
Ni 2.16

What am I doing wrong and what happened to the gold?

Thanks for you help.
Bob

 

[jimdoc]

The connectors are only gold plated. Melting the whole
thing is not the way to go. The niton probably only reads
what is on the surface.

 

[koebeef]

Niton is not good for this. In fact, it is not even good to test metals on its own. It does well for stainless steel but for other alloys you will need a grinder to see what really is under any coating.

 

[Anonymous]

Thanks for the responses.

My dreams of getting rich have been dampened.

I have 20 to 30 thousand of another type of connector which the XRF showed 10% Au.

I wish I could post some photos so you could see what these connectors look like.

I have been reading the board quite a bit and was hoping to avoid using chemicals.

Anyone near Tampa that is familiar with using chemicals to strip the gold and share in the proceeds?

Thanks,
Bob

 

[goldsilverpro]

I think the Niton is totally worthless for testing gold plated material. All it's going to do is give you false hopes. The only way I know of to test the pins, without chemicals, is to use special equipment to determine the plating thickness. There's probably never been a connector pin made that contained 10% gold. They would be worth $1360/pound and that's ridiculous. The hightest I've ever seen were worth about 6% and they were made in the 30s or 40s. It would be stupid for the manufacturer to put on more gold than is needed. For pins that are worth $60/pound, a possible figure for some pins, the gold content would be 0.44%.

Think about this. Say you had two types of pins that had the same thickness of gold plating and were made from the same alloy of base metal. Let's say both were cylinders and were the same length but one type was twice the diameter of the other. The larger pins would weigh 4 times as much and would have 2 times the surface area of the smaller diameter pins. All in all, the larger pins would be worth only half as much, per pound, as the smaller pins. However, the Niton would give the same reading on both types.

The 2 reasons you can't accurately test gold plated material with the Niton

(1) It requires homogeneous material. A base metal alloy coated with gold (a different material) is not a homogeneous material. When you melted it, you formed a homogeneous material. The true gold percentage was then too low to be within the capability of the Niton.

(2) It doesn't take into consideration the dimensions of the part.

The Niton only penetrates the skin of the object. If the gold were quite thick, it would not totally penetrate the gold layer and would probably give a reading of close to 100% gold. In your case, it penetrated the gold layer and went into the base metal slightly. The reading you got was a combination of the two.

If you had several different standards of different known gold thicknesses, made of the same base metal as the unknown, you could probably draw a curve using the gold percentage readings of the various standards versus their actual gold thicknesses. You could then test the unknown part and determine the gold thickness from the graph. Of course, the gold on the standards couldn’t be so thick that it prevented penetration into the base metal. This is possible but not practical, since you would need a different set of standards for each base metal alloy of the different type parts you were testing.

 

[patnor1011]

if you want to use XRF correctly you have to melt sample, pour to bar and then read with XRF. this is good for stuf with high gold or PM content as melting gold plated pins and sampling will not show any gold - gold on them is less than measurable percentage of pin mass...

 

[tamerakshar]

XRF machines will be faulty if the specimen is more than 8mm thick, cause as we all know XRF deals with the surface.
For all newbies; don't expect more than 4gm per pound from any type of plated scrap, even military scrap.