# Opinions on pitfalls before attempting unorthodox procedure:



## HAuCl4 (May 27, 2010)

Hello all. Very nice forum, lots of knowledge, and pictures, and procedures. A gem.

I would like to get feedback from members here on the possible pitfalls of this plan, and/or how to make it work better, improvements, etc.

The goal is to reach 9999+ fineness in gold material that contains silver, copper, and other base metals, but no platinum group. I wish to achieve 9999 without dissolving the gold into solution, i.e. The metal is to stay in metallic form all the way from the beginning to the end.

Call this stupid, or a search for the truth, or an experiment, or exercise, or whatever. Let's see if it can be done.

The procedure (in summary) I intend to use is (please feel free to criticize, suggest, etc.):

1-Inquartation with lead. Fusion of the gold, and lead added to the melt.
2-Melt dropped in water to make shot/leady flakes.
3-Digestion in boiling dilute nitric acid, several times, till absolutely no reaction occurs in fresh acid.
4-Thorough wash with distilled water till no acid remains in gold powder left.
5-Boiling in HCL.
6-Repeat step 4.
7-Wash in concentraded sodium hidroxide (to remove any remaining silver compounds).
8-Repeat step 4.
9-Dry gold powder, wrap in 10 times its weight of lead foil and place on large magnesite or bone ash cupel.
10-Cupel at about 950 °C till all lead is absorbed or volatilized as litharge.
11-Raise the temperature till the metal in the cupel melts again, and carefully add sprinkles of sodium or potassium nitrate mixed with borax. Could do this in a fresh cupel/dish?.
12-Let button cool, and then test for fineness.

Would the button left even approach 9999 ?.

Thanks in advance for all opinions.


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## machiavelli976 (May 27, 2010)

"inquartation with lead"! where to find very pure lead? my best result , inquarting with 90% electrolytic copper ,10 % carat gold wasn't above 99.5 % after all kind of washing and acid leaching. got round shiny buttons without any flux but i know there still was some contaminant in every button. 999.9 maybe using a electrolytic cell.


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## machiavelli976 (May 27, 2010)

another thing. to reach the highest purity gold must pass thru a solution atom after atom, not crystal after crystal like in inquartation does.


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## HAuCl4 (May 27, 2010)

I'm not so certain mach. During a fire assay, a similar process is used, and the gold never goes into solution (except into the lead), and always remains as metal. What gold remains is better than 9999 unless some mistakes are made in the assay. If there is a lot of silver in the lead, that could bring an issue. Point taken.

This is why I want to get to the bottom of this.


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## goldenchild (May 27, 2010)

I think no matter how many times you repeat step 4 there will always be contaminants. Even the tinyest grains of gold can be encasing inferior metals. You are also re-introducing lead into the mix when the gold is at a fairly high purity in the process. That makes no sense to me.

I now think to myself this, before I try cockamamie(not saying this is)experiments. If it was an easier and more efficient way to do it, someone probably would have already done it already. 

I say just try it with a small amount of gold and let us know what you get. The worst that can happen is it doesnt work and you have to refine it the old fashioned way


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## Palladium (May 27, 2010)

Miller process will give you about the best your going to get without wet refining.


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## goldsilverpro (May 27, 2010)

> During a fire assay, a similar process is used, and the gold never goes into solution (except into the lead), and always remains as metal. What gold remains is better than 9999 unless some mistakes are made in the assay



I don't think you can make this assumption. According to Bugbee, when using proper procedures, about .05% silver is retained in the gold after parting. Therefore, the gold purity would be 99.95%, at best. Even worse, Shepard and Dietrich give a figure of .1% silver retained in the gold, which would give a gold purity of 99.90%, although their statement is vague and I may be misinterpreting it. 

I don't understand the logic of using lead for inquartation. I would that the that lead would be more difficult to part than silver. You would have to use very weak nitric, say 1:7, nitric:H2O to have any chance of removing the lead. Lead nitrate is not very soluble in strong nitric and will form crystals, which block the dissolving.

Concerning the cupellation portion of your scheme, Bugbee gives figures, from various researchers, of lead and other metals being retained in the gold assay beads. One found that from .30 to .37% lead is retained in the gold bead. Another found .45% total impurities. And it seems that the larger beads retained more than the smaller ones. Also consider that, if metallic silver is retained in the gold during parting, you won't be able to remove it by oxidation after cupellation.

I could probably think of other problems but, in general, I personally don't think you have any possible chance of your scheme producing 9999 gold.


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## HAuCl4 (May 28, 2010)

Thanks guys for all comments. I think I had several wrong beliefs about assays. I thought that the beads were finer than they actually are it seems. What is the current standard way to measure fineness and where can the equipment be purchased/leased?


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## goldsilverpro (May 28, 2010)

When you get up into the 9995, or better, range, I would think the most reliable way is to first have all the impurities analyzed. The percentages of all the impurities are then totaled and and this figure is subtracted from 100% to get the purity, in percent, of the gold. I believe that ICP is used for this.

BTW, I really don't know the exact accuracy of the fire assay, as it is dependent on many variables. One source that seems reliable says it is accurate to .02%, using best techniques.


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## goldsilverpro (May 28, 2010)

Several years ago, an Italian company made closed-circuit gold refining equipment, called Aure8, based on inquartation and the subsequent dissolving of the copper or silver in nitric. They claimed that, by using several fresh batches (3) of of progressively stronger nitric, a gold purity of 9999 could eventually be reached, thus avoiding the aqua regia step. The success of this seems dubious, since it seems the equipment is no longer being made. About the only thing left on the internet concerning this is this study of the process.

http://www.ganoksin.com/borisat/nenam/wgc-refining.htm

Although not perfect, I made a Word doc of the article


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## HAuCl4 (May 28, 2010)

Thanks GSP. It seems that to actually properly test this, I'd need an ICP assay machine. It seems rather expensive.


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## Harold_V (May 29, 2010)

HAuCl4 said:


> This is why I want to get to the bottom of this.


Then lose the idea of processing with lead. It is very damaging to the quality of gold, and has a considerable affinity for same.

If you'd like to process without dissolving, I encourage you to explore the Miller chlorine process, or zonal refining. Likely both are beyond your ability, however. 

Harold


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## HAuCl4 (May 29, 2010)

Harold_V said:


> HAuCl4 said:
> 
> 
> > This is why I want to get to the bottom of this.
> ...




Cheers Harold. Found very little on the zone refining method (link below). Looks interesting.
http://www.tutorvista.com/content/chemistry/chemistry-iii/metals/metals-refining.php
http://www.tutorvista.com/content/chemistry/chemistry-ii/metals/metal-refining-methods.php

Do you have any, more detailed info regarding zone refining?.

It may be beyond my ability now, but I can learn or try at least.


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## goldsilverpro (May 29, 2010)

HAuCl4,

No offense, but I'm having trouble understanding your motive in all of this. Is this just a mental exercise or are you really looking for a way to process gold? You seem to have some knowledge of fire assaying and basic refining. Is this derived from only book learning or is it from actual experience? If the former, I would suggest you get some hands-on experience, using the traditional methods, under your belt before trying to re-invent the wheel.

The Miller chlorine method is not really a refining method, since it only raises the the gold to about 99% pure. It is used to prepare gold for the Wohlwill cell, which is a refining method and can produce 9999 gold. Both are expensive to set up and are generally only viable for large volume. 

I have only read about zone refining and have never seen it done. I know it's quite expensive to set up. In very simple terms, the impurities in a bar are pushed to one end by melting only a small zone of the bar and moving this melted zone from one end of the bar to the other. The zone moves very slowly and it can literally take days to do one bar. Therefore, only a section of the bar is pure and, I think, the greater the amount of impurities, the smaller this pure section is (actually, I think the purity is graduated throughout the length of the bar). The zone refining can be repeated. I don't think this would be applicable for something with a lot of impurities, such as karat gold. As I understand it, its main purpose is to further purify already quite pure materials. For example, I seem to remember reading of 12 nines silicon being produced by this method. To get this, they probably start with at least 4 nines material.


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## HAuCl4 (May 29, 2010)

I have hands on experience GSP.

I just want to know, for certain, if very pure gold can be produced without passing the metal thru a solution. 

Call it a mental exercise or whatever. Search for knowledge?.


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## Harold_V (May 30, 2010)

HAuCl4 said:


> Do you have any, more detailed info regarding zone refining?.


Sorry, I do not. GSP's comments in that regard are pretty much on target for that which I would have said. I have heard of it, but did no exploration. In all the years I refined, I simple double refined my material, and was more than satisfied with the quality. So much so that the small Wohwill cell I built was never put in service. 



> It may be beyond my ability now, but I can learn or try at least.


I hope my comment wasn't taken as a personal affront. I don't mean to judge you as a person---but the fact that the equipment that would be required in order to accomplish the task is generally well beyond that which a person can afford, especially if they are nothing more than a hobbyist. The zonal process would ultimately be best performed with an induction heater. It might even perform faster than GSP proposed, a great deal depending on the wattage of the furnace and the coil design----but induction furnaces of any consequence are expensive and require considerable power---often three phase. I offer you as an example, the one I own. It is a 50 kw motor generator type (old technology), built by Ajax Magnethermic. It requires 240 volt 400 amp three phase service. At full load, it requires nearly 200 amps to operate, plus you must be able to start the motor/generator, which is a 75 horse motor. Were it not for the soft start capability, 400 amps would not be adequate. 

Sorry I'm not more help.

Harold


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## HAuCl4 (May 30, 2010)

Thanks Harold. I had never heard about zone refining. It seems fascinating, but as you said, very involved with expensive equipment,etc.

I watched a Miller chlorination setup years ago. It's much simpler than people think, but it is for lots of 100 oz min.(my guess). And no matter what they tried, they said they could never get above 997-998 in fineness. They were processing up to 500 oz in a few hours.


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## Barren Realms 007 (May 30, 2010)

Harold_V said:


> HAuCl4 said:
> 
> 
> > Do you have any, more detailed info regarding zone refining?.
> ...



That thing sounds like a monster Harold. That is a heck of a load.


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## Harold_V (May 30, 2010)

HAuCl4 said:


> Thanks Harold. I had never heard about zone refining. It seems fascinating, but as you said, very involved with expensive equipment,etc.
> 
> I watched a Miller chlorination setup years ago. It's much simpler than people think, but it is for lots of 100 oz min.(my guess). And no matter what they tried, they said they could never get above 997-998 in fineness. They were processing up to 500 oz in a few hours.


That's pretty much my understanding as well. Speed is its one outstanding feature. I included it only because you had asked about bringing metal fine without dissolution. 

I got so comfortable with the AR process that I thought nothing of dissolving 75 ounces per session, which was my normal procedure. 

Harold


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## Harold_V (May 30, 2010)

Barren Realms 007 said:


> That thing sounds like a monster Harold. That is a heck of a load.



Heh! The load is large, no doubt, but so is the power supply. The motor/generator is a single unit, hung vertically. The entire power supply unit weighs 3 tons. 

Harold


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## HAuCl4 (May 30, 2010)

Harold_V said:


> HAuCl4 said:
> 
> 
> > Thanks Harold. I had never heard about zone refining. It seems fascinating, but as you said, very involved with expensive equipment,etc.
> ...



I think you did well Harold. A normal procedure, which was very familiar and comfortable to you, and which you made a business off, which made it even better: Profitable. Most of us here can only aspire to that as hobbyists and/or small batch processors.

On the other hand, hobbyists are free to explore and experiment and ask questions of the elders (  ). For example:

Last week I was watching Steve's fine videos on the Per-Sulphuric cell for deplating...and during today's afternoon nap, the idea hit me: What if I hang a say 990 fine gold anode on a similar cell and a copper cathode on same?. If I have a slightly modified cell, (hand drawn pic attached), then the gold should drop as anode "mud", and the silver, copper, etc. should go into the electrolite and perhaps plate on the cathode?.

This gold "mud" would be finer and, after several good washes, may even make the 9999 grade?.

I understand the gold in this instance actually went "into solution" for a few moments (thanks to the per-sulphuric acid created by the voltage at the anode), and then inmediately re-precipitated as it contacted the electrolite again.

Not anywhere an "invention", but a variation of an existing setup, that might produce some very fine gold, especially if properly washed afterwards. I think I may build one of these to experiment. (It sounds like a better idea than the lead sequence I started with...lol).

What do you guys think?.


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## butcher (May 30, 2010)

HAuCl4 good idea but? 
unless the gold is already fairly pure, there will be co-deposit of gold with the copper, in an electrolyte that will plate out copper.

in an electrolyte and electrode that will not plate copper, but copper is put into electrolyte solution, and gold is in mud slimes there is still contamination of your gold.

you may be able to clean up the gold some, using membranes or filter bags but it will still have contamination and need refining.

I like the idea you want to come up with better mouse traps, but first it's better to learn about all the mouse traps that have been invented, why they work and why they dont, you can be wasting your valuble time trying to build a better light bulb, but without understanding how light bulbs already invented work and why they dont you are just wasting your time.

funny how many people want to build a prepetual machine and do not understand the principles of how machines work or the laws of physics.

spend your time learning the existing methods well why they work and why they don't, then you may see some point that they can be altered or improved, but without that understanding your just shooting in the dark,
people have been working on refining for thousands of years and with that much brainpower, do you not think that you can come up with a better mouse trap without understanding the principles? 

I do not mean this to discourage you, but like the miner with fools gold and gold fever,just trying to help you see its not that easy to get rich, or come up with better mouse traps untill you understand what real gold is or the mouse trap fundamentals.


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## HAuCl4 (May 30, 2010)

butcher said:


> HAuCl4 good idea but?
> unless the gold is already fairly pure, there will be co-deposit of gold with the copper, in an electrolyte that will plate out copper.
> 
> in an electrolyte and electrode that will not plate copper, but copper is put into electrolyte solution, and gold is in mud slimes there is still contamination of your gold.
> ...



Either you did not read my post or it is you who must do some studying...  

Only an experiment will help at this point.

No offense.


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## butcher (May 30, 2010)

no offence taken, I just read the post above and did not go back further in my reading of this thread, so maybe I do need more study about what you are trying to accomplish here. I will re-read it.


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## butcher (May 30, 2010)

after rereading this thread I stand by my suggestion for helping you to achive your goals.

I can be wrong that would not be unusual.


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## Barren Realms 007 (May 30, 2010)

Harold_V said:


> Barren Realms 007 said:
> 
> 
> > That thing sounds like a monster Harold. That is a heck of a load.
> ...



OHHH boy I just got a woody...........I like things like that. 8)


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## Harold_V (May 30, 2010)

HAuCl4 said:


> Last week I was watching Steve's fine videos on the Per-Sulphuric cell for deplating...and during today's afternoon nap, the idea hit me: What if I hang a say 990 fine gold anode on a similar cell and a copper cathode on same?. If I have a slightly modified cell, (hand drawn pic attached), then the gold should drop as anode "mud", and the silver, copper, etc. should go into the electrolite and perhaps plate on the cathode?.


Unfortunately, it doesn't work that way. Not all substances will be dissolved, so the solids that are liberated drop to the bottom, just as gold does. The cell functions for the recovery of silver as well as palladium, so they would be included in the harvest, assuming they were a part of the parent bar. 

If you read the patent on the process, you find that if voltage is controlled properly, base metals are not dissolved. That was the purpose of the stripping cell, to salvage items that were good aside from defective plating. That means that any traces of anything not soluble will find themselves included in the harvest, assuming they are liberated as the gold is dissolved by the cell. 

However, the one thing in your favor is that the recovered gold is very finely divided---often bordering on being colloidal. Persistent (acid) washing *may* yield a high quality product, but I'm of the opinion that that would not be the case. Even gold precipitated from relatively clean solutions is difficult to wash free of contaminants----so I expect that in this case, you'd struggle to exceed 9995. If that were not the case, gold so stripped would not require further processing. 

Do keep in mind, achieving 4 n's isn't easy. I don't know that I ever achieved that level of fineness. 

Harold


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## nickvc (May 31, 2010)

Just a suggestion but if you are willing to use a cell why not make a small Wohlwill cell as GSP referred to earlier admittedly you will have to dissolve some fine Au to create the gold chloride solution but if used properly you should produce high purity gold if you have a high grade feed into the cell.


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## HAuCl4 (May 31, 2010)

Thanks guys. I'll do some experimenting when I have the chance, and I'll try to remember to report my findings here.

I did not know that gold could be dissolved in any way with sulfuric acid till I saw Steve's cell video. Therefore I do not have any hands on experience with the process. A little more investigation yielded that the gold is not dissolved by sulfuric acid, but the combination of concentrated acid AND voltage at the anode, produce per-sulfuric acid which is what dissolves gold (and other metals to a lesser degree). When this compound of gold starts to travel to the cathode it becomes in contact with the normal sulfuric acid and precipitates as gold is NOT soluble in sulfuric acid. (i.e.: The per-sulfuric environment only occurs close to the anode). The other compounds copper sulphate and silver sulphate are somewhat soluble, and either travel to the cathode or drop as crystals of sulphate along with the gold.

In short; The gold went into solution atom by atom and was precipitated shortly after. I infer that with very thorough washing and boiling in acids, etc. it will be FINER than the original anode. How much FINER is the question that can only be answered by experimentation.

Of course I could also go the traditional ways of dissolving in AR, etc, etc. But if man did not dare to experiment and try new things...we would all still be eating fruit in trees somewhere in Africa...which is not neccessarily a bad thing if one is happy doing it.

Cheers. Thanks for the opinions and ideas, and now I'll just shut up.

P.S.: By the way, on the accuracy of fire assays: Years ago I had access to a digital balance with 0.0001 gr accuracy, and by making assay proof samples of about 2 grs of fine gold (from a small SBS ingot), we determined that the accuracy of our assaying in the range from 9999 to 18 Kt jewellery was 0.0002 when using 1 gr assay beads and 0.0001 when using 2 grs assay beads. There are microgram accurate balances these days that will no doubt tell how accurate the fire assay really is, but I'm convinced that is more than enough to tell if something is 9999 or 9995. Without an ICP machine (which I've never seen but would like to!  ).


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