Large Precious Metal Assay

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D

DOK

Member
Joined
Nov 4, 2022
Messages
6
Location
AZ
Hello,

I am a NOOB here, but not to precious metals. Whereas, I have a solid chemistry background and I would feel comfortable setting up a lab to separate precious metals, time becomes a constraint. I am designated as the 2nd on the list of C.M. Hoke’s book… the dreaded “DENTIST”! I see that most of the forum does not fall in this category, and my kind seems to just throw away or haphazardly send out PM scrap with very little vetting of what we have and the true value of what we have (Easy or lazy scrap surrenderer). Middle men come to dental offices and give meal gift cards to front desk staff to take scrap, a trick i have witnessed among colleagues many times. These dentists aren’t stupid, but more overwhelmed with treating people primarily and running a fully staffed office rendering scrap metal an insignificant factor to think about.

Recently, I decided to turn in my scrap, which I know has a high volume of Au & Pd primarily followed by Pt & Ag. These large refiners, who want you to send scrap through the mail no matter the volume and trust it will arrive, and will NOT allow you to visit their facility I find questionable. I had nearly 20+ pounds of isolated scrap (No teeeeeth & very little porcelain), gathered over many years, that I knew was quite valuable. I personally weighed and and dropped off at a refinery that advertised 100% guarantee or you can receive your assay back at absolutely NO cost. After the scrap was rendered into a large assay (160 0z) and analyzed with a vacuum pin tube & Inductively Coupled Plasma machine, I was given my assay composition. Upon, telling me this I was surprised to hear the payout percentage. I inquired and was told the “Dentist“ payout was 66% but on my company account (which most dentists don’t have & they overlooked I had)) it showed 84%. Due to an immediate lack of trust, even though they acknowledged their mistake, I picked up my assay and am waiting to decide what to do moving forward. This really began my deep dive into refinery research and has left me quite confounded. I since have been quoted from a few refineries nationwide:

All metals: 95% & 90%

Also Varying % of metals: 97% Au, 88% PGMs

I was wanting the refineries to do an independent test of their own to evaluate the composition and volume of the assay so they were comfortable but wanted a firm agreement on me delivering and % of metals to be paid so I am not traveling haphazardly throughout the country to be told PGMs aren’t paid for. These refineries have either been reluctant to commit to % on paper, will not allow me to drop off and will not insure delivery. The assay % report indicated this assay to be worth $250K+. Let me just pop that in the mail and cross my fingers!

I am willing to invest in the separation of this metal assay into individual precious metals as I enjoy Chemistry, but want to see what everyone here in the forum suggests as per a refinery I can trust and will agree to simply allow me to drop off, watch their basic analysis and agree upon % paid out for all metals before engaging. Or render the process myself and sell to local mint I have a relationship with. Thank you for everyone’s time in reading and pondering this for me.
 
Hi! Not sure about the location indicator, but I live in Arizona, USA. Thank you for your response.
 
You certainly have a decent volume of material to refine if you so decide but, and there are several large buts, is it worth your time effort and expense.
What ever you do to your material you will likely not get spot on any of it , you may get 98%+ for the gold if separated and in decent amounts but for your PGMS you will be lucky if you get more than 93%.
Separating the PGMs from the rest will expose you to very toxic salts that can kill or incapacitate you so proper lab safety will be essential including a fume hood and scrubbing plus lab grade glass and chemicals including acids and somewhere to do this without complaints from neighbours.
Once you have separated the values, not easy with PGMs in fact almost impossible , you will need melting equipment to make bars and then assays to prove the purity.
If you still decide to proceed then be aware that you will have large volumes of highly toxic waste solutions to safely dispose of or to treat to allow you to get rid of .
Now allowing for the cost involved the time to learn how to do this safely and competently is it worth it to you?
You could do this but as I point out it’s not easy or cheap and will take some time, not sure of your hourly wage but you may make more working your job than learning and hands on refining.
 
Nickvc,

That was a very informative, much appreciated & extremely helpful response . With all that being said I am hoping more members will chime in with best practiced refineries that will respect my following requests:

1.) allow me to come to their facility & watch their initial independant re-evaluation with XRF, etc.
2.) agree to a firm % of payout for Au, Ag & PGMs (Prior to traveling)

I am willing to travel within USA to facilitate this and be treated fairly & equitably.
 
nickvc said:
You certainly have a decent volume of material to refine if you so decide but, and there are several large buts, is it worth your time effort and expense.
What ever you do to your material you will likely not get spot on any of it , you may get 98%+ for the gold if separated and in decent amounts but for your PGMS you will be lucky if you get more than 93%.
Separating the PGMs from the rest will expose you to very toxic salts that can kill or incapacitate you so proper lab safety will be essential including a fume hood and scrubbing plus lab grade glass and chemicals including acids and somewhere to do this without complaints from neighbours.
Once you have separated the values, not easy with PGMs in fact almost impossible , you will need melting equipment to make bars and then assays to prove the purity.
If you still decide to proceed then be aware that you will have large volumes of highly toxic waste solutions to safely dispose of or to treat to allow you to get rid of .
Now allowing for the cost involved the time to learn how to do this safely and competently is it worth it to you?
You could do this but as I point out it’s not easy or cheap and will take some time, not sure of your hourly wage but you may make more working your job than learning and hands on refining.
Click to expand...
Just curious, % of spot you mentioned above, do you get them just for bigger quantity (like 30+ozt) ? Probably impossible with few ozt of metal. Here I can get like 73% for Pd and 93% for Au at local buyer, altough I sell for slightly higher %tage to someone else. 85-90 % spot for PGMs is quite ramping difference :D
DOK said:
Hello,

I am a NOOB here, but not to precious metals. Whereas, I have a solid chemistry background and I would feel comfortable setting up a lab to separate precious metals, time becomes a constraint. I am designated as the 2nd on the list of C.M. Hoke’s book… the dreaded “DENTIST”! I see that most of the forum does not fall in this category, and my kind seems to just throw away or haphazardly send out PM scrap with very little vetting of what we have and the true value of what we have (Easy or lazy scrap surrenderer). Middle men come to dental offices and give meal gift cards to front desk staff to take scrap, a trick i have witnessed among colleagues many times. These dentists aren’t stupid, but more overwhelmed with treating people primarily and running a fully staffed office rendering scrap metal an insignificant factor to think about.

Recently, I decided to turn in my scrap, which I know has a high volume of Au & Pd primarily followed by Pt & Ag. These large refiners, who want you to send scrap through the mail no matter the volume and trust it will arrive, and will NOT allow you to visit their facility I find questionable. I had nearly 20+ pounds of isolated scrap (No teeeeeth & very little porcelain), gathered over many years, that I knew was quite valuable. I personally weighed and and dropped off at a refinery that advertised 100% guarantee or you can receive your assay back at absolutely NO cost. After the scrap was rendered into a large assay (160 0z) and analyzed with a vacuum pin tube & Inductively Coupled Plasma machine, I was given my assay composition. Upon, telling me this I was surprised to hear the payout percentage. I inquired and was told the “Dentist“ payout was 66% but on my company account (which most dentists don’t have & they overlooked I had)) it showed 84%. Due to an immediate lack of trust, even though they acknowledged their mistake, I picked up my assay and am waiting to decide what to do moving forward. This really began my deep dive into refinery research and has left me quite confounded. I since have been quoted from a few refineries nationwide:

All metals: 95% & 90%

Also Varying % of metals: 97% Au, 88% PGMs

I was wanting the refineries to do an independent test of their own to evaluate the composition and volume of the assay so they were comfortable but wanted a firm agreement on me delivering and % of metals to be paid so I am not traveling haphazardly throughout the country to be told PGMs aren’t paid for. These refineries have either been reluctant to commit to % on paper, will not allow me to drop off and will not insure delivery. The assay % report indicated this assay to be worth $250K+. Let me just pop that in the mail and cross my fingers!

I am willing to invest in the separation of this metal assay into individual precious metals as I enjoy Chemistry, but want to see what everyone here in the forum suggests as per a refinery I can trust and will agree to simply allow me to drop off, watch their basic analysis and agree upon % paid out for all metals before engaging. Or render the process myself and sell to local mint I have a relationship with. Thank you for everyone’s time in reading and pondering this for me.
Click to expand...
Analysis would be very good for your knowledge, as quite a bit of dental material can contain mercury, and you sometimes should pay penalty for metals such as cadmium or mercury in the material. I am just thinking out loud.
If you have melt assay done, and results from ICP, then it is easier to you to mail guys with quantity and %tages of elements. Much more straightforward than travelling and wasting your time.
From forum members, I will say Lou could potentially be interested in your material. He runs a refinery and has plenty of experience with PGMs :)
 
Good Morning Orvi,

There is NO mercury in the assay, as the scrap was strictly crowns (caps for the older folks) that were removed and NO fillings whatsoever, which contain the mercury you speak of. It has already been assayed into a 160 oz bar of mixed metals (Au, Ag & PGMs) which is what was used in crowns over the decades, mostly Au & Pd with small Amounts of Pt and Ag perhaps trace amounts of Ni. I would want the refinery to do their own independent analysis.
 
DOK said:
Good Morning Orvi,

There is NO mercury in the assay, as the scrap was strictly crowns (caps for the older folks) that were removed and NO fillings whatsoever, which contain the mercury you speak of. It has already been assayed into a 160 oz bar of mixed metals (Au, Ag & PGMs) which is what was used in crowns over the decades, mostly Au & Pd with small Amounts of Pt and Ag perhaps trace amounts of Ni. I would want the refinery to do their own independent analysis.
Click to expand...
That is nice for you, that it is Hg-free.
I meant that if you have some analysis done (%tages of individual metals in the assay), it would be easier to contact refineries and directly state quantity and composition of the material - that way they will know in advance what kind of material it is, and could preliminary quote the spot %tage for each metal involved, based on composition and quantity, as these two factors are most important for them. Ask about the procedure, if it would be possible to accompany your lot to the smelting, watch your material along it´s way etc. How money will be paid, and strict agreement on percentages paid for individual metals.

Don´t be afraid, they will do their own independent analysis :) their money would be at stake without it.
 
Just did a lot that size for a customer. His was high noble and quite good despite it not being 100% perfectly prepared (some PFMs not completely ceramic free).

He dropped it off and got a receipt and I ran his as a dedicated lot.

The witnessing aspect (of the sampling) is something I allow and as this isn’t small money so you should expect it.

Traditionally, I add an equal weight of copper to the dental before sampling, I take three melt samples, roll all three and cut them into replicates: three for my analysis, three for the customer, and three for reserve if there’s a variance. You can get an XRF for ball parking but ICP/fire assay are the way to go.

There will be Au, Pd, Pt, and Ag. I’ve never seen Rh of any significant quantity nor even Ir/Ru. On average it’s mostly a gold and palladium proposition with enough silver to annoy me. Ga, In and Cr often cause phase segregation. An honest refiner with knowledge about dental sampling will explain the issue with getting a fair sample and do so in advance.

Unfortunately for me (and you, perhaps!), I’m waiting on a new Inductotherm or I’d offer to help.
 
Hey Lou,

Thanks for coming aboard!
Just curious how much Cu do you usually mix in with a sample of 5 lbs or 10 lbs?
How long before you are up & running again?
Are you located in Calie?

Yes, Scottsdale Mint. 😁
 
I figured as much! Please tell Josh I said hello. I imagine splitting time between there and Casper is pretty rough for him and his team. You're dealing with the right people though--he runs a top notch organization making top notch bullion and is a man of his word.

To 10 lbs we would add an equal amount if possible. I was at the International Precious Metals Institute Sampling and Analytical Conference a few weeks back in lovely Golden, CO and there was a discussion I missed on dental sampling. I imagine much of the talk was about what I've also experienced--varying assays on melt thiefs and phase segregation on cooling. Certain mixtures of precious metals will not homogeneously freeze.

We are out of Ohio and we are about 3-4 weeks out.

Best,
 
Last edited:
To add confirmation to Lou,s comments about PGMs in melts with other elements and values it’s a very well known problem even with jewellery wastes where stratification is very common with gold and PGM mixed bars.
 

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