How accurate is a pin sample ? misc questions

[irv]

I own a company that brokers over 3 million a year in jewelry scrap which consist of 10kt to 24 kt. The refiners I have used in the past all melt the gold in a crusible and after adding borax and sodium nitrate they take a pin sample to determine the karat purity for payment. My questions are:

1. how can a batch of melted gold, say with a value of $500,000, be accurately tested for purity with a pin sample that only weights 3-4 grams?

2, does the fact the refiners has added borax and sodium nitrate reduce the accuracy of the gold content when doing a fire assay on the pin sample?

3. I always get my pin sample checked by an independent assayer and he is usually just a little bit higher in his analysis of the purity, however, he and the refiner are both testing a sample of my gold which contains all the additives which the refiner put in during the melting process....DO THESE ADDITIVES REDUCE THE PURITY RESULTS OF A PIN SAMPLE?

4. What do the refiners in the states do with the gold bricks they create from people like me if they can't refine to .999 fine and sell products to the trade?

5. Finally, I could significantly increase my business if I can increase my yields and I am think in order to do this I need to get with a major refiner such as Johnson Mathey or a similar firm, am I wrong. My current refiner claims he pays me 99% of melt and assay.........my problem is how accurate is the assay

any advice would be greatly appreciated.

 

[Anonymous]

My current refiner claims he pays me 99% of melt and assay.........my problem is how accurate is the assay

If you could learn to do a quick assay,then there would be no doubt.
It is all contingent on how homogenious the material was,prior to taking the pins sample.The more homogenious,the more accurate.

how can a batch of melted gold, say with a value of $500,000, be accurately tested for purity with a pin sample that only weights 3-4 grams?

That is performed thousands of times a day,with very accurate results.Now whether your refiner is being truthful with you,is another story......which leads me to this...

I always get my pin sample checked by an independent assayer and he is usually just a little bit higher in his analysis of the purity, however, he and the refiner are both testing a sample of my gold which contains all the additives which the refiner put in during the melting process.

Are you not seeing a great big red flag here?!?!

 

[irv]

am I missing something? I am with my gold all the time from arrival, melt, pin sample received and only leave my gold ( now in brick form) when I get an advance check of 90% to be settled after the fire assay which usually takes 7 days

 

[irv]

would it be better if I sold my sold in seperate lots of only 10k, only 14k, only 18 etc.?

thank you all for taking the time to respond to this new member

 

[Anonymous]

There are MANY tricks to seperate you from your gold.When you know how to process gold from start to finish,you realize just how easy it is to take advantage of someone that is not aware of what is going on,or does not have things checked twice.In your case ,if you are having it checked twice,and the independant assay is coming back higher,then there is your proof.You could not have any more proof than that.
One member told a story about a refiner that had hollowed out the center of a graphite rod,and put copper shot inside,so that when the melt was stirred with the rod,the copper would melt,giving the customer a lower assay result.
The more you know,the less likely it is to happen.Be prepared,and have your butt covered at all times.

 

[goldsilverpro]

I own a company that brokers over 3 million a year in jewelry scrap which consist of 10kt to 24 kt. The refiners I have used in the past all melt the gold in a crusible and after adding borax and sodium nitrate they take a pin sample to determine the karat purity for payment. My questions are:

1. how can a batch of melted gold, say with a value of $500,000, be accurately tested for purity with a pin sample that only weights 3-4 grams?

2, does the fact the refiners has added borax and sodium nitrate reduce the accuracy of the gold content when doing a fire assay on the pin sample?

3. I always get my pin sample checked by an independent assayer and he is usually just a little bit higher in his analysis of the purity, however, he and the refiner are both testing a sample of my gold which contains all the additives which the refiner put in during the melting process....DO THESE ADDITIVES REDUCE THE PURITY RESULTS OF A PIN SAMPLE?

4. What do the refiners in the states do with the gold bricks they create from people like me if they can't refine to .999 fine and sell products to the trade?

5. Finally, I could significantly increase my business if I can increase my yields and I am think in order to do this I need to get with a major refiner such as Johnson Mathey or a similar firm, am I wrong. My current refiner claims he pays me 99% of melt and assay.........my problem is how accurate is the assay

any advice would be greatly appreciated.

To answer your questions.

1. Yes, if the melt was thoroughly mixed before the sample was taken. This is hard to do in a gas furnace. A graphite or quartz stir rod only moves the metal in a circle. The metals tend to layer and you need almost something with a bend on the end so you can move the metal up from the bottom. On the other hand, the internal motion from an induction furnace keeps the melt mixed and stirring isn't necessary, although I do it anyhow.

With a gas furnace, instead of a pin sample, I prefer to cast and drill the bar half-way through on a drill press in 4 or 5 places, using a specific drill pattern and technique.

2. No.

3. No. Since those chemicals end up transferring some of the copper, etc., to the slag, the purity will increase somewhat, but the final weight will decrease proportionally. In the end, though, you have the same total amount of gold that you started with.

For 4 and 5, I don't feel that you have enough control of your metal. Were I you, I would buy a gas crucible furnace, melt and stir as well as possible, cast bars, drill samples, and have the samples assayed - at least duplicates and preferably in triplicate. At the present, there are "gray areas" in your dealings. Melting your material, yourself, would mostly eliminate these. Also, when the refiner figures out how much he wants to pay you, he has to consider that there were drill holes in the bars you shipped him - so, he knows that you know the values. I would also lock in the price of what you have with the refiner and ship more frequently, maybe weekly. Turn your money. You are generating about 2.2kg, gross weight, of karat scrap per week. That can be melted in a small melting furnace readily available from a jewelry supply.

 

[Harold_V]

I'm afraid I'd have to agree with GSP------

Harold

 

[irv]

Thanks to everyone who was kind enough to reply to my message

It seems for me to melt my gold in a gas furnace would require some EPA issues and since I am in a major city with tight rules the permits to melt gold and exhausting the smoke would be a serious problem for me.

I feel there is more gold in my scrap than I am getting and wonder if I seperated my gold by karats and did individual melt lots if that would better than melting all karats in one lot.

Again, any thoughts or advice is greatly appreciated

 

[qst42know]

What do the pros think of welding fume collectors for a melt of this size?

I would think welding fumes are potentially more hazardous than a karat gold melt.

http://www.lincolnelectric.com/en-us/equipment/weld-fume-control/Pages/weld-fume-control.aspx

 

[Westerngs]

Welding fumes... Maybe they are more dangerous, maybe not.

It seems to me in welding the worst fumes would be zinc oxide fumes. You would get metal fume fever which if bad enough could kill you, but I think it would take a lot of welding fumes.

But karat gold contains quite a bit of zinc as well and it oxidizes readily when heated, so the danger is the same or more so.

Either way, you have to be careful and use good exhaust to the extent possible.

As to melting gold, different cities have different air regulations, but I think GSP mentioned mentioned 2.2 kg/week or roughly 70 t.o. That is nowhere near enough to cause a concern for a municipality. Irv needs to check the air regulations for his location but I think he will find few issues.

 

[goldsilverpro]

I feel there is more gold in my scrap than I am getting and wonder if I seperated my gold by karats and did individual melt lots if that would better than melting all karats in one lot.

Are you talking about you doing the melting or the refiner doing the melting? In either case, I can't see how doing separate melts on each karat would make any difference. You also must consider that a separate assay would be required on each bar and that can get expensive. If you were just selling your loose jewelry to a buyer, sorting by karats would be necessary.

If you are truly getting paid less than you should, based on the agreement you made with the refiner, there can only be one answer - the refiner is taking some off the top. However, even if the refiner were 100% honest, you wouldn't know that he was unless you melted your own material.

There is a tendency for all of us to over-evaluate our own material. Are you aware that much of the karat jewelry is about 1/2K low and a full karat under is not that uncommon? Are you removing all the stones yourself? Some 10K class rings contain lead or resin under the stone. With chains, there are often other metals involved. If a ring had been reduced in size, a lower karat solder could have been used. I could go on and on. Melting your own material will eliminate these questions.

Can you provide data on some lots? When you compare your estimate of what you think you should have gotten to what you actually got from the refiner, what is the percent difference?

 

[Harold_V]

The one thing that interests me is the discussion of fumes. Assuming scrap gold isn't laden with garbage, the fumes coming from a heat likely wouldn't be any more noticeable than the smoke from a cigarette. I would go so far as to suggest that a single lot of gold, melted once, weekly, could be accomplished in a small work room with nothing more than an open window for ventilation.

Is that an ideal setup?

No, it isn't, but it is a functional setup.

Harold

 

[qst42know]

I would assume the biggest risk in karat gold melting would be the zinc and possible cadmium content. I have encountered old lead solder repairs as well.

Cadmium does enhance the properties of brazing alloys (I have used both with and without) it wasn't a concern in the old days and may still be in use in some jewelery producing countries.

Power ventilation of some sort would be prudent if only for what may be included. A fan in the window might be enough so the smoke doesn't linger.

 

[irv]

I just today got my settlement check from my refiner and would like to share the details to see if anyone has any suggestions as to changes I should make or situations I should be aware of to enhance my return. Thanks again for all comments, it is helping me learn and be helpful to my customers as well. I am not trying to get blood out of a turnip, I just want to be paid what I have negoiated with the refiner to receive.

before processing weight 14,581.00 dwt
after processing weight 14,455.60 dwt
lot fee of $150, 99% return on melt and assay

this is a mixed lot of 10k to 24k with the bulk being 14k.........very clean, very few little stones

REFINERS ASSAY 55.559%
INDEPENDENT ASSAY RESULTS 55.67%
MY NITON XL2 XRF RESULTS 56.31%

I calculate the difference between the refiner and independent assay to be $1,314, my xrf assay calculates a difference of $8,893

I guess now it is understandable why I can not feel comfortable with the numbers and I am trying to get a good understanding.................any thoughts as to what I should do to run my business better?

 

[irv]

follow-up comment

all three assays are from the pin sample taken from the melt when it eas in liquid form with a glass tube

which is better for the seller-- a pin sample or a drilling of the bar

after the bar cools down the refiner puts it in a sandblasting machine and it comes out with like a satin finnish, I assume this provides some profit for the refiner, also as the gold is being melted the exhaust is sucking up all the smoke into their ventilation system (do I lose gold if they cook it too long?)

trying to provide all the details

 

[goldsilverpro]

I just today got my settlement check from my refiner and would like to share the details to see if anyone has any suggestions as to changes I should make or situations I should be aware of to enhance my return. Thanks again for all comments, it is helping me learn and be helpful to my customers as well. I am not trying to get blood out of a turnip, I just want to be paid what I have negoiated with the refiner to receive.

before processing weight 14,581.00 dwt
after processing weight 14,455.60 dwt
lot fee of $150, 99% return on melt and assay

this is a mixed lot of 10k to 24k with the bulk being 14k.........very clean, very few little stones

REFINERS ASSAY 55.559%
INDEPENDENT ASSAY RESULTS 55.67%
MY NITON XL2 XRF RESULTS 56.31%

I calculate the difference between the refiner and independent assay to be $1,314, my xrf assay calculates a difference of $8,893

I guess now it is understandable why I can not feel comfortable with the numbers and I am trying to get a good understanding.................any thoughts as to what I should do to run my business better?

Did you watch the refiner through the entire melting and sampling procedure?

Did he use a gas furnace or an induction furnace?

Did the independent assayer fire assay the pin sample?

 

[irv]

yes, I watch and stay with my gold during the whole process and my pin sample is cut from the same pin as the sample they keep. I actually get two pin samples . There was a very slight variance when I checked each sample I retained from this melt on my xrf unit, I thought they should be identical.

The refiner uses an induction furnace powered by electric. The refiner is very large with probably 50-75 employees

The independent assayer says he uses a "corrected fire assay" oddly enough when the assayer returns my pin sample it appears to be in the same condition as when I mailed to him. In the past everytime I have confronted the refiner with the Assayers result they have paid me the difference.

Also, the refiners settlement sheet shows silver at 7.367% of which I get paid and Platinum at 0.14oz of which I get paid as well

 

[goldsilverpro]

Sounds like all the bases were covered. Not too many ways the refiner could get to you under those conditions, although they can be pretty tricky. Very little weight loss after melting. The independent fire assay was only .2% away from the refiner. I trust a fire assay much more than the xrf.

 

[irv]

I WOULD LIKE TO SINCERELY THANK EVERYONE THAT HAS REPLIED, I FEEL BETTER ABOUT MY WAY OF SELLING SCRAP, BUT, STILL FEEL THE REFINER IS GETTING ME FOR MORE THAN THE 1% SPREAD PLUS HIS REFINING CHARGES.

I JUST BELIEVE WHEN MY 14,000 DWT BAR IS REFINED TO EXTRACT PURE GOLD THE AMOUNT ULTIMATELY RECOVERED FROM MY GOLD WILL BE MORE THEN A 3 GRAM PIN SAMPLE ASSAYS ............ I'M I TOTALLY WRONG?

 

[jimdoc]

What's up with the all caps? We can hear you just fine without them.

Jim