NTR METALS...A++ Refiner!

[chawimac]

I just wanted to put in my 2 cents on NTR.

They are nice people, but not very pro. They have many satellite office, which is why they are not a good refiner. They use small ovens, so you need to do many melts for small lots. I think 5kilos is the max on their furnace. The staff usually donno what they are doing, as they are poorly trained. Again, too many offices.

There is no transparecy with them even when you go to a local office. They XRF so you could lose a good percent just right there, and they never offered the assay pins. I had to ask for them. The assays of course were off. Not saying they were scamming me, most likely it was a cheap chinese XRF to blame. Not that I saw the XRF or the melt process, that part was way too sketchy for me.

I sold like 30 kilos once, so learned my lesson cheap. They might work well for little guys that sell a couple grams here and there, but if you deal in kilos you should work your way up. I don't mean JM, Metalor or Argor either; they are too big. Transparency and service is key. Mail me a check is not a service, that is expected.

Thnx,

Chawi

 

[Dan Dement]

Hi Guys,

I am new to the Forum but not a newby to Gold Buying. I am on my Third XRF machine and Second S.G. Scale. I use NTR but have tried quite a few different people. With my latest, very accurate XRF, I have been able to test different methods of gold testing. I have compared Pin Samples, drillings, end mill drillings, cuttings, Wedges, thin bars, thick bars, cutting in half, cutting in quarters and just about anything else you want to try. I have two Induction Melters so remelting, mixing, and rechecking is easy to us to do. I may not be the biggest buyer but I roll the payouts fairly quick at about 500 grams a payout. Now, my latest XRF is only a couple of weeks old but had the President of the company come out and help me zero in the readings against my 25 master standards and his 25 standards. My current machine is a $38,000 machine and the XRF's that NTR uses are $100,000 tri read that require a 3 minute read. Lots of difference guys and they are not going to run the 8-12 times like I do. The biggest eye opener for me is the fact that the lowest purity of Gold is in the exact center of a sawed ingot. Enclosed is a picture of a sawed ingot with the readings. The readings on the edges are actually outdise and the lowest reading is the dead center of the sawed bar.

All I can say is NTR pays me what I figure the gold. Now, it has taken me two years for playing and buying bunches of equipment to get all this figured out. I have had the exact same feelings that everybody on this board feels. For me, it's like walking into a Bank and throwing them a sack of money and say now much is it? When I walk in, I know how much it is and not that we don't argue but the arguing needs to be based on science. The scary figure is the fact that the center is the least pure of the ingot and where do they pull the pin sample from? Another fact that I am working on proving is, the longer you leave the gold in the ingot to cool, the more the difference in the outside and core! I drop it in the pickle while the metal is still moving. I know, it does not make sense and I am running more tests as I have time! All I can say is that I now feel like I am getting paid the proper amount.

Thanks to Rick Pearse about telling me about this forum!

Dan

 

[4metals]

Welcome to the forum Dan.

For years there has been the question drill sample or pin dip sample and I can say from having first hand experience assaying thousands of samples that samples from pin dips have less of a spread than drill samples.

I have never personally sliced a bar and assayed different sections as you did. It is interesting because when a drill bit goes in it spans these different regions of the bar and some turnings are higher and some lower. Fortunately an assay is made up of multiple pieces of turnings never just 1 little piece. This explanation holds up well to what I experienced with assay spreads.

Theory has it that the different cooling rates of different metals causes the segregation. It seems to be less prevalent in a dip or possibly it is symmetrical in a dip so it is not noticed. When I cut up a dip for assay, I cut off and do not use the ends for assay. Then I cut short lengths to give out between 1.5 and 2 grams for assay. The section of pin is rolled out thin in a rolling mill and cut into small pieces. Individual cups for the assay are made up by weighing out the small pieces of rolled and cut pin sample.

 

[Noxx]

That's a bit strange, there's a 5.4% difference in purity between the top and center.

You are melting the gold using an induction furnace right ? Are you stirring with a graphite rod also ?

 

[nickvc]

Well i have melted gold for years and usually know within a very small margin what to expect, the hallmarking rules here in the UK are very strict, and I am rarely out by very much as to actual content using drill samples. With margins so slim I find it hard to believe that any refiner would accept losses of the magnitude been discussed as they would be losing money hand over fist.
Never going to happen is it?

 

[MiguelRosas]

Hi Guys,....

The scary figure is the fact that the center is the least pure of the ingot and where do they pull the pin sample from?

Dan

Dan -

Welcome to the forum.

I do find that your assay readings are very interesting, and something I would like to hear more about as you test your theory - but in regards to your question, Hi-Tech does pull a liquid pin sample from the center of the crucible. However, with an induction furnace, and utilizing a graphite rod to stir the melt several times (but most importantly immediately before the sample is taken) the sample you take should be consistant with the true purity content.

The problem I see with cutting a bar in half and assaying those parts (much like drilling holes) is exactly like you say - if the top cools faster and allows gold to sink then the the assay will be off / if the melt was not stirred before the pour, more gold has settled to the bottom / if you didn't heat up the mold enough, that can affect the three sides which the gold contacts / etc. etc.

In my opinion, by taking a pin sample from the middle - rolling it out flat, and assaying that upon multiple locations, you will find that the margin of difference between each end of the sample is very consistant.

But I may be bias.

 

[4metals]

I wonder if the saw cut dragged metal across the surface and is giving erroneous readings? In a true metallurgical analysis the surface would be polished before taking a reading, that may give better numbers.

I can assure you that no refiner, honest or dishonest, wants to deal with a sample that is not representative, that is why they will all assure a mix is good and the pin sample is taken when the melt is hot enough to have all of the metals molten and well mixed.

 

[lazersteve]

I wonder if refined 99%+ purity gold exhibits the same variance across a solid bar?

Perhap the presence of base metals causes the gold to move to the center of the melt?

Steve

 

[Westerngs]

I can actually contribute something useful here.

About ten years ago I took a 1300 t.o. bar that we had melted in a gas fired furnace (we stirred the heck out of it) and took drill samples every two inches on top and the same on the bottom (rectangular bar - about 30 inches long if I remember correctly).

We also took pin samples of the melt in the center and 4 sides.

The bar assayed somewhere in the 60% Ag/30% Au/ 10% Cu range.

Long story short, on the drillings, the range for silver from high to low was about 0.4%. The range for gold was about 0.2%. On the pin tube samples, the range on the silver was about 0.1% and the range on the gold was <0.06%.

We always use pin tube samples on lots > 50 t.o. now.

It is hard to believe a 3% range on a bar that small, unless it was not melted correctly or stirred well. I think the fault is with the surface of the bar, oxidation plays heck with XRF.

 

[4metals]

Those results are in keeping with what I have found over the years ranging from the old days with a gas furnace up to the induction days.

I never took a dip from anywhere other than the center though. Variation in a molten crucible of well stirred metal, especially with the roll of a good induction furnace, would surprise me.

 

[Westerngs]

You are right. Always use an induction furnace if possible.

We still struggle with melts when using both gas fired furnaces and electric resistance furnaces. You would think we would have learned by now to always buy induction furnaces, but we have some people that are just set in their ways. Then of course, we use gas furnaces for material that required fluxing.

 

[Dan Dement]

Guys,

Thanks for the warm welcome. To clarify, first it is well, and I mean well mixed as I melt very small buy and then keep remelting until I get up to the 500 grams or so. Now, I have tried very method but fire assay and let's be clear, fire assay really only tells you the gold. Another thing not mentioned that I filter the metal to sure we don't have any hidden mysteries inside. I have seen a stainless center to a gold watch case hidden that a graphite rod did not detect. As far as gold being dragged into the center, well I lose about 10 grams every time I cut from the bar so not a lot of dragging going on. Of course, it's not lost and the Dyson little vac really works very well for about four minutes. I have to axe to grin but all you guru's need to look at other methods. If drilling a hole thru several mm's of a bar is a preferred method then why is the center that much different? Pin samples can vary 1-1.5% from one end to the other coming from the middle. As far as not getting hot enough, what part of me manufacturing platinum & palladium did you not read. Guys, I got an induction melter that can melt TI! I just got a new super accurate SG scale and by accurate, it's based on a diamond scale going to .001 carat. Can't find them the scale or melter on a wand yet? Guess who does the beta testing for them?

Just a little old fat mean guy in Texas who counts pretty good! It's nice to have smart friends that help carry my big behind.

Peace,

Dan

 

[Westerngs]

Dan,

I think for the most part we will have to agree to disagree. I have never seen the assay ranges you claim on properly melted material.

 

[4metals]

I have to agree with Westerngs, you are talking about differences which are larger than the charges refiners get. If the spreads were truly that large on all bars the cost of refining would be considerably higher to cover the losses. Refiners today work within splitting limits of 1/4%.

As far as gold being dragged into the center, well I lose about 10 grams every time I cut from the bar so not a lot of dragging going on.

What I meant by dragging is the soft malleable metal can spread a thin skid mark over the surface which may effect the XRF. Back in the days of measuring plating thickness by cross sectioning the piece and polishing it to a mirror finish, I learned you have to polish down past the smudge from cutting to get good readings. Your best XRF will also come from a perfectly flat surface as the rays travel out and back and are not reflected off. That may be the issue here. I am only speculating because in practice I have never seen spreads as you are describing.

 

[Dan Dement]

Guys, before you roast me for not mixing, get a hacksaw and try it for yourself! I got an induction melter on a wand. I am mixing the metal as I am tilting it. You can't mix it more than I mix it unless somebody has a eating blender induction melter. Now, what I have not tried is really heating up the ingot. Got plenty of torches so that is next.

Always next week!

Dan

Might introduce a new response SIIK. The last three words are if I Know,

 

[4metals]

The intent is not to roast but to get the right answer, then everyone benefits.

I've seen thousands of bars but never cut one in half, that's not the way they're sampled. I will however dip a bar this week and drill it, I'll report back top bottom and dip assay.

BTW I never use a cold mold.

 

[Dan Dement]

In the scientific search for the truth, I am going to have NTR melt and analyze the next 300 gram plus batch. Then I am got going not to sell it and slice it in half and run all the numbers. This should certainly put to rest any question of my mixing ability.I do not claim to be a refiner nor any expert on this matter! That's why I am here asking questions. Excuse me if I question the answer of doing the same thing a thousand times and not expanding my horizon. I am certainly not afraid of putting my money where my mouth is. Funny how on the picture I posted, the outside is nearly all the same but only in the inside is the biggest difference. Stratification, solidification, or difference of cooling of the alloys Sh** If I Know but I will find out the answer! Interesting occurrence that I have noticed is the "Bread Loaf" effect on cooling thicker bars. This effect seems to be worse on the lower karat bars but almost no effect on pure bars. This seems to indicate that it is in cooling effect of the lower melting point alloys which are congregating in center as it cools. You can always tell the top and bottom by the bread loaf dip in the alloyed metals that I am buying. Do you get the bread loaf effect in pouring pure bars? If not, could be an indication that it is zinc and copper cooling first and pushing the gold to the outside. To me, a thin slice out of the center should be a true average of a bar but it is not! It's about 2% low with almost no trace of FE. Funny what an accurate XRF will tell you.

Onward thru the Fog! Until next week with more buys, more sells, and more tests. Since this NTR thread was hijacked by me let say two very IMPORTANT facts: 1. NTR is paying me almost exactly what my figured average is which within tenths of what my new SG scale calls it. 2. NTR started paying me 98.5%.

Everybody has got to make a profit!

Peace,
Dan

 

[goldsilverpro]

I am in total agreement with 4metals. I have also sectioned many samples and measured many plating thicknesses with a microscope with a built in measuring scale - a metallograph. Gold really smears easily. For an accurate reading, before sectioning and mounting, we had to plate a nickel back-up layer on top of the gold. This locked in the gold on both sides, prevented the smearing, and gave a much more accurate reading.

I think 4metals hit the nail on the head. I can see the great possibility of smearing and, therefore, great potential errors in using a XRF on a raw, rough, hacksawed surface. This surface would certainly not represent the actual gold content, in my experience.

If I were to research this, I would try all the sampling methods on a single bar - pin sample, pattern drilling, saw-through, dip and shot, etc. I would fire assay and XRF everything. Then, I would refine the gold, myself - no NTR. I would then compare all the results. I would bet that induction melting and the fire assaying of pin samples would give the best results.

 

[Dan Dement]

I am glad you guys agree but either one of you have tried the test. I certainly could grind or sand it flat but I don't think you would agree with that either. I have quartered the samples also and have gotten similar results. Not trying to be belligerent over it but first it's not mixed well then it's metal being dragged along throwing off the results. Neither one of you have stated what XRF you use and the proof of the pudding is the checks I receive. I will be the first to agree that the fact of the dead center being the least pure is alarming. I will do a few more experiments and report back. I have a couple of friends who got PHD's in Chemical Engineering and who has worked for Johnson Mathey for twenty five years who just recently retired. Time to bring in the Dover Pro's! Next thing I am going to try is the Cut the heart out of the Watermelon Trick which will cut a V section out of the dead center and test it and then remelt it from the rest of he bar. That should either prove or disprove the drag theory!

Appreciate you guys experience but all the experts thought the world was flat at one time.

If your right, I will be the first to admit it. However, it's hard for me not to believe hard numbers taken trying to as Scientifically as possible! Probably going to buy a larger metal hacksaw or get fine metal blades for 70 1/2 length.

Peace guys, I am only puzzled by the truth! You do have a hacksaw and a strong arm don't you? If you don't have a good XRF then speak up and admit it.

Dan

 

[its-all-a-lie]

i think i know how this will end :roll: