New to forum and struggling with claims made by refiner / buyer.

[RichardSukhoi]

I recently send in a modest amount of 14,18,21 k to Midwest.
I was very disappointed with two claims they made, and came here to learn the truth. First is weight loss. Sure a primitive setup with open flame will evaporate gold, but common sense would say a commercial setup would use induction, inert gas, and vapour capture. Do people agree 2 to 4% weight loss is unreasonable at a commercial facility? Next is concentration loss. I can’t believe their 8% loss of gold concentration. I didn’t look up vapour pressure at melt temperatures but again, distillation capture. Just using a Pyrex or graphite column would condense vapour. Or use electrostatic means. I await expertise. Anyone?

 

[Yggdrasil]

I recently send in a modest amount of 14,18,21 k to Midwest.
I was very disappointed with two claims they made, and came here to learn the truth. First is weight loss. Sure a primitive setup with open flame will evaporate gold, but common sense would say a commercial setup would use induction, inert gas, and vapour capture. Do people agree 2 to 4% weight loss is unreasonable at a commercial facility? Next is concentration loss. I can’t believe their 8% loss of gold concentration. I didn’t look up vapour pressure at melt temperatures but again, distillation capture. Just using a Pyrex or graphite column would condense vapour. Or use electrostatic means. I await expertise. Anyone?

Welcome to us.
I hope someone will chime in on this.
It is not within my comfort zone as I have never dealt with a refinery.

 

[RichardSukhoi]

Welcome to us.
I hope someone will chime in on this.
It is not within my comfort zone as I have never dealt with a refinery.

I am sure there are proper and well developed rigs but here are my thoughts on how a low loss setup would look. First an induction heated graphite crucible. Then make a chimney by stacking graphite plates with matching hole and bonding with zirconium cement), then bond a Pyrex chimney with a curve or droop down. Cooling air could be blown into chimney or rather inert MIG gas.

A high temperature capillary tube could be run into the top of crucible just past induction field. Run a purge a few minutes and maybe pause during melt phase to avoid overcooling tbe melt. With all this metal vapours (no oxides will form due to inert gas), will stick to the pyrex. After some accumulation, the gold can be recovered off the Pyrex with a nitric acid wash.

Comments?

 

[4metals]

We have received a few complaints about Midwest of late. all we can do is say what happens when gold melts and how it effects the assay.

From years of melting gold jewelry, both with gas furnaces, induction furnaces, and even assay furnaces, the gold is not going up the stack in any measurable quantity. If it is a salt that is different, but I assume you meant metallic scrap.

A 2-4% weight loss does seem high for karat gold. Some weight loss will occur but even 1% is extreme. That is unless you had a lot of stones or other material (decorative beads) that could burn off. The metals like zinc, which is in all karat alloys, will burn off as base metals oxidize and precious metals do not. The zinc, due to its lower melting point is more prone to volatilization.

Are you sure there was no gold filled costume jewelry in the lot. Gold filled often volatilizes quite a bit more than karat scrap. It is not uncommon for some gold fill to be in with karat scrap, I have seen it many times.

I am not sure what you mean by an 8% loss of gold concentration. do you mean you lost 8% of your expected gold content? Gold does not volatilize off and go up the stack and the assay (percentage of gold in the melt) can increase because of other base metals gassing off but the gold content will not increase but the assay can rise.

You are barking up the wrong tree assuming gold was lost due to melting. Not saying gold was not lost in your payment but it didn't go up the stack.

 

[orvi]

It depends. Melt loss can be that high, if you have quite a bit of fillers/solders/lots of sprig locks/dirt/paint etc. in the material. If it was cleaned and picked-through material, I doubt 4% loss is realistic.

I am not familiar with "concentration loss"... If that means to say that "sorry, we lost 8% of your gold", than this is outrageous.

All in all, I don´t like these phrases like "processing loss", above "concentration loss" and other purposefully added nonsense terms, just to steal your material and legitimate it behind some empty phrases.

I do agree that there are always losses. But in order of % ? That´s called rip off.

 

[orvi]

I recently send in a modest amount of 14,18,21 k to Midwest.
I was very disappointed with two claims they made, and came here to learn the truth. First is weight loss. Sure a primitive setup with open flame will evaporate gold, but common sense would say a commercial setup would use induction, inert gas, and vapour capture. Do people agree 2 to 4% weight loss is unreasonable at a commercial facility? Next is concentration loss. I can’t believe their 8% loss of gold concentration. I didn’t look up vapour pressure at melt temperatures but again, distillation capture. Just using a Pyrex or graphite column would condense vapour. Or use electrostatic means. I await expertise. Anyone?

This is indeed why I never let any "company" to melt my material. There are hard to melt materials, and not everyone actually need to own induction furnance to melt catalysts or some high melting PtRh/Ir alloys - I know. But regular stuff like plated escrap, silverware, mixed karat - there is no catch, low melting points, easy to do it with few hundred USD worth of equipment.

Melting karat is simple, easily done procedure even by inexperienced hobbyists. Once you have the lot molten and thus homogenized, you make dip sample from the melt. This will serve as your reference for the future transaction.

It is also much more convenient and less stressful to carry the few grams dip sample, than kilogram bar of molten karat.
You got it at least shot by XRF at some local jeweller´s shop (even crappy "yellow" Thermo machines are OK accuracy for karat) - to serve as referrence point for you. If you operate in bigger scale, you let some reputable assay house to do regular fire assay on the dip sample.

Then when you will go sell the stuff, you will know precisely what you have and what you are asking for it - reducing possibility of any "shady" practices from refinery.

For few hundred USD, you can buy yourself electric furnance capable of melting few kg´s of karat in one go. Even DIY gas furnance will work perfectly for this chore. If you are in this business for real and want to continue, I really advise to learn how to do this. It will protect you from any chance of this shady practice and all empty statements

 

[RichardSukhoi]

Thank you everyone for your thoughtful and informed responses.
Tonight I will do the arithmetic and calculate just what I Midwest apparently took from me.
But let me directly quote the person I spoke with; “when you melt 21 K gold you get 0.82-0.84 and not .875, 18 you get .68-.71 and not 0.75, 14K you get .54-.56 and not 0.583”. I asked how that was possible as gold has a low vapour pressure compared to most alloys. Note all of this is after a 2-4% weight loss due to “melting”!

 

[4metals]

We live in a complicated world, a world where something stamped 14K can legally be a half a karat low. In Europe I understand the karating laws are tighter but here in the US a bit of leeway was built into the system. Supposedly to accommodate solder, which is lower karat to melt faster, and findings that may be parts of an assembled piece. What the BS story you have been told by your refiner of choice is, that every piece takes advantage of this leeway and their assumptions are the low ball figures.

Since you had a melt loss it is fair to assume they melted the lot. when a lot is melted and assayed, the number that matters is the bar settlement weight and the assay result. That says there are X grams of gold in the lot. The low ball numbers they told you are just a way to justify their low result. And a typically small lot without representation is never run with a proof sample, they simply multiply the result by .995 to lower the assay a bit more.

Maybe I have been living under a rock for too long but I never heard of 21 karat gold. 10,14,18, and even 22 (popular in India) but never 21.

Out of curiosity, how big was the lot you shipped?

 

[RichardSukhoi]

We live in a complicated world, a world where something stamped 14K can legally be a half a karat low. In Europe I understand the karating laws are tighter but here in the US a bit of leeway was built into the system. Supposedly to accommodate solder, which is lower karat to melt faster, and findings that may be parts of an assembled piece. What the BS story you have been told by your refiner of choice is, that every piece takes advantage of this leeway and their assumptions are the low ball figures.

Since you had a melt loss it is fair to assume they melted the lot. when a lot is melted and assayed, the number that matters is the bar settlement weight and the assay result. That says there are X grams of gold in the lot. The low ball numbers they told you are just a way to justify their low result. And a typically small lot without representation is never run with a proof sample, they simply multiply the result by .995 to lower the assay a bit more.

Maybe I have been living under a rock for too long but I never heard of 21 karat gold. 10,14,18, and even 22 (popular in India) but never 21.

Out of curiosity, how big was the lot you shipped?

I will do all the math later but just for now regarding 21 K, it’s common in Egypt and Syria. Here is a close up of my proof mark and an image from the internet listing Egyptian proof marks.

 

[FrugalRefiner]

We live in a complicated world, a world where something stamped 14K can legally be a half a karat low.

Up until what were called the plumb laws in, I think, the 1980s or so, there was actually up to a 1 karat total allowance. The main portion of the "item", like a ring or bracelet could be up to a half karat under the stamped value. If there was solder involved, e.g., from sizing a ring or assembling parts of a bracelet, another half karat was allowed.

These tolerances date back to the early laws of this country. At the time, techniques weren't quite as refined as they are today, so the laws tried to provide for the small jeweler who didn't have the most accurate scales, access to pure metals to create their alloy, etc.

By the 80s the standards were tightened, but you don't know if the piece you're buying was made before or after the change. You also probably don't know who made the piece. Remember, anyone with $20.00 can buy a stamp that says 14K or whatever they want and make jewelry. There's no guarantee it's actually 14K.

I can't speak for the regulations in other countries, or the inherent honesty of those making jewelry there.

Dave

 

[anarxi]

21-karat gold, also known as 875-carat gold, is represented by several alloys. These are alloys of metals such as copper, silver or palladium with pure gold. For example, the use of copper gives a reddish tint.

875 gold is soft and ductile. The 21K hallmark is often used in jewelry and is especially popular in India, where consumers buy more gold than in any other country. Jewelers in the Middle East are also in favor of 21K gold, which is sometimes sold as Arabian gold.

 

[4metals]

875 gold is soft and ductile. The 21K hallmark is often used in jewelry and is especially popular in India, where consumers buy more gold than in any other country. Jewelers in the Middle East are also in favor of 21K gold, which is sometimes sold as Arabian gold.

Thank you for the clarification, in my career I never bought gold by the piece, I always melted individual pieces together into bars and paid on assay. So the question of individual karat rarely came up and the question of the bar assay always came up.

 

[goldshark]

Another possible factor - the fake "Au" jewelry that abounds. Alloys similar in color to Au alloys, but not a trace of Au. A lot is stamped 14-18 K. Did you analyze all material before sending it in? A bath in Nitric will show the phonies.

 

[RichardSukhoi]

We have received a few complaints about Midwest of late. all we can do is say what happens when gold melts and how it effects the assay.

From years of melting gold jewelry, both with gas furnaces, induction furnaces, and even assay furnaces, the gold is not going up the stack in any measurable quantity. If it is a salt that is different, but I assume you meant metallic scrap.

A 2-4% weight loss does seem high for karat gold. Some weight loss will occur but even 1% is extreme. That is unless you had a lot of stones or other material (decorative beads) that could burn off. The metals like zinc, which is in all karat alloys, will burn off as base metals oxidize and precious metals do not. The zinc, due to its lower melting point is more prone to volatilization.

Are you sure there was no gold filled costume jewelry in the lot. Gold filled often volatilizes quite a bit more than karat scrap. It is not uncommon for some gold fill to be in with karat scrap, I have seen it many times.

I am not sure what you mean by an 8% loss of gold concentration. do you mean you lost 8% of your expected gold content? Gold does not volatilize off and go up the stack and the assay (percentage of gold in the melt) can increase because of other base metals gassing off but the gold content will not increase but the assay can rise.

You are barking up the wrong tree assuming gold was lost due to melting. Not saying gold was not lost in your payment but it didn't go up the stack.

So here

We have received a few complaints about Midwest of late. all we can do is say what happens when gold melts and how it effects the assay.

From years of melting gold jewelry, both with gas furnaces, induction furnaces, and even assay furnaces, the gold is not going up the stack in any measurable quantity. If it is a salt that is different, but I assume you meant metallic scrap.

A 2-4% weight loss does seem high for karat gold. Some weight loss will occur but even 1% is extreme. That is unless you had a lot of stones or other material (decorative beads) that could burn off. The metals like zinc, which is in all karat alloys, will burn off as base metals oxidize and precious metals do not. The zinc, due to its lower melting point is more prone to volatilization.

Are you sure there was no gold filled costume jewelry in the lot. Gold filled often volatilizes quite a bit more than karat scrap. It is not uncommon for some gold fill to be in with karat scrap, I have seen it many times.

I am not sure what you mean by an 8% loss of gold concentration. do you mean you lost 8% of your expected gold content? Gold does not volatilize off and go up the stack and the assay (percentage of gold in the melt) can increase because of other base metals gassing off but the gold content will not increase but the assay can rise.

You are barking up the wrong tree assuming gold was lost due to melting. Not saying gold was not lost in your payment but it didn't go up the stack.

Some details on my experience with Midwest. I sent in 5 items of 14,14,21,18,18K. The 21k was Egyptian and I know that at the time their gold had tiny tolerances on karat so almost certainly very close to .875. The two 14 K bands were made from remelted 14 k so any wire would have been skimmed off, so probably not worse than 13.5k. The cross and earring were euro 750, the earring from a prestigious company, so I doubt worse than 17.5 K. The mass was 0.762 Troy Oz, Midwest reported a weight loss of 3.4% by melting. They paid against a gold weight of 0.463 so I got 83.6%% paid compared to hallmark concentration. So not that bad, but seems not so good either. I think it is apparent they are being incompletely honest.

 

[4metals]

I think what Midwest does wrong, based entirely on claims made by unhappy members here is they do not state or have any minimum charge for processing. But to take this lot by example, the after melt weight was .463 oz times an assay of 0.863 equals .399 oz gold content. times $2300 per ounce equals $919. They claim to only charge 5%. But 5% of the total value is $45.95. What company can operate on that small a margin. They had to receive it in, either melt it or evaluate each piece, refine it to get the gold out, and cut a check to you for 5% of the gold value. Pretty tall order for $46 bucks!

I know refiners that will take in 2 ounce stone removal lots and they all have a minimum lot fee, some as high as $250. From a business point I understand minimums. From a customers point I understand claiming one low price to get the work in. But overall, the potential business Midwest loses by squeezing clients has a cost as well. I guess for them, it pays off.

 

[snoman701]

I would be surprised if they even melt. There are a lot of "refiners" that just pay on karat stamp after testing. I know more than one that have posted pictures and videos of their "shop" and that shop turns out to be someone else's melt shop. It feels mighty dishonest, but the line of people happy to vouch for them gets them through I guess?

The FTC has tightened the standards, and karat jewelry produced since the change must meet much more stringent requirements than 1/2 karat. I can't remember when this change was made, but it's in the last thirty years....and it is tight. Like 1/10 of a percent or something.

 

[cejohnsonsr1]

I seem to recall someone pointing out recently that Midwest charges 15% for small lots. Not 5. I’ve never heard of melt loss unless we’re talking about the part that isn’t gold and gets scraped off as slag.

 

[anarxi]

I think what Midwest does wrong, based entirely on claims made by unhappy members here is they do not state or have any minimum charge for processing. But to take this lot by example, the after melt weight was .463 oz times an assay of 0.863 equals .399 oz gold content. times $2300 per ounce equals $919. They claim to only charge 5%. But 5% of the total value is $45.95. What company can operate on that small a margin. They had to receive it in, either melt it or evaluate each piece, refine it to get the gold out, and cut a check to you for 5% of the gold value. Pretty tall order for $46 bucks!

I know refiners that will take in 2 ounce stone removal lots and they all have a minimum lot fee, some as high as $250. From a business point I understand minimums. From a customers point I understand claiming one low price to get the work in. But overall, the potential business Midwest loses by squeezing clients has a cost as well. I guess for them, it pays off.

It is possible that not each batch is processed separately, but several different orders are collected and melted in “one pot” and then distributed based on an approximate estimate of the invested gold from different orders.

all pre-processing:
record the weight and measure the sample with a device.
This will take no more than 2 minutes.

 

[RichardSukhoi]

It is possible that not each batch is processed separately, but several different orders are collected and melted in “one pot” and then distributed based on an approximate estimate of the invested gold from different orders.

all pre-processing:
record the weight and measure the sample with a device.
This will take no more than 2 minutes.

I like this point. An honest dealer could weigh, slice open, XRF at the cut, as basic pre processing.
But let’s say you had a proper induction heating rig and could quickly weigh, melt, flux, skim, a small batch (say 1 oz), weigh, XRF. That also would take just a few minutes. Let’s say your costs with all overheads are $2 a minute. Let’s give 15 minutes per order, $30. So charge everyone $60 process fee. Then pay 90% to give your business the 10% to pay for wet chemistry refining to pure metal and profit. That seems reasonable to me.

 

[anarxi]

I like this point. An honest dealer could weigh, slice open, XRF at the cut, as basic pre processing.
But let’s say you had a proper induction heating rig and could quickly weigh, melt, flux, skim, a small batch (say 1 oz), weigh, XRF. That also would take just a few minutes. Let’s say your costs with all overheads are $2 a minute. Let’s give 15 minutes per order, $30. So charge everyone $60 process fee. Then pay 90% to give your business the 10% to pay for wet chemistry refining to pure metal and profit. That seems reasonable to me.

You reason too nobly, perhaps as you would have acted...

Among other things, operating an induction furnace also costs money..
shot the pistol from both sides at best and threw it into the bag...