# Need Help Guys



## Anonymous (Jan 2, 2010)

Hello members I am a new member of this forum hope u guys will help me.

I have an alloy of Gold+Copper and did not know that how much amount of copper is mixed 
with gold.
Here in Pakistan use the refining by using water displacement method.

Look at the Picture.
DELETED BY A MODERATOR - SEE BELOW

It is a receipt of one of Refine centre.
it has two weights 1)In Air (50.7130) 2)In water wich is actually not given in receipt.(assume
48.520)
My question is that from which formula i can find the Total impurity of an alloy as
shown in pic.
(This Formula is based on Archimedes Principal) 
But i want to know in Mathematical form. I searched a lot but unable to find.

Plz guys help mee,Its urgent...........


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## Barren Realms 007 (Jan 2, 2010)

I'm not totaly understanding your question. The sheet you show gives you your resulsts. Are you looking for percentages? Or are you trying to find out how to perform this test yourself?

Try a search under "specific gravity" and see if this is the info you are looking for.


http://www.gold-nuggets.org/specific-gravity-test.htm

The Specific Gravity Test (used to calculate the gold content of gold nuggets that contain a mixture of gold and other materials) In this example of the specific gravity test, we use gold mixed with quartz. Simply put, the formula is 3.1 x the weight in water, minus 1.9 x the weight in air:

Wet nugget weighs 74.5 grams x 3.1 = 230.95
Dry nugget weighs 96 grams x 1.9 = 182.4

230.95 - 182.4 = 48.55
31.1 = number of grams per ounce
48.55 / 31.1 = 1.56 ounces of gold

Original dry weight = 96 grams / 31.1 = 3.08 ounces.
Subtract the difference between the wet and the dry:
3.08 ounces - 1.56 ounces = 1.52 ounces.
Therefore what is left is 1.52 ounces of quartz.

"Wet" = weight in water - Put container of water (enough water to cover nugget) on scale. Tare (zero) out scale. Hang nugget by string in water. Note weight.

The specific gravity for gold is 19.3.
The specific gravity for quartz is 2.65.
The ratio between gold and quartz is 7.28 X. 


--------------------------------------------------------------------------------


What is specific gravity? Specific gravity is simply the weight in grams of one cubic centimeter of a metal. Here are specific gravities and other properties of a few more metals:
Metal Symbol Specific Gravity Melting Point (ºF) Melting Point (ºC) 
Copper Cu 8.96 1981 1083 
Gold Au 19.32 1945 1063 
Iron Fe 7.87 2802 1539 
Lead Pb 11.34 621 327 
Nickel Ni 8.90 2651 1455 
Palladium Pd 12.00 2831 1555 
Platinum Pt 21.45 3224 1773 
Silver Ag 10.49 1761 961


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## samuel-a (Jan 2, 2010)

check this out:
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=41&t=6193&p=54229#p54147


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## goldsilverpro (Jan 2, 2010)

Ajmalshaa, 

You can't use specific gravity to predict the percentage of gold in an alloy unless you know what other metals are involved and their percentages. 

In the attachment, there are several sample pages from the book I wrote. On page 41, I knew the most likely percentages of the various metals used to produce a particular karat alloy. From these numbers, I calculated the possible specific gravity spread of these particular alloys. The formula I used was: S.G. of the alloy = 1/[(decimal fraction of metal A/S.G. of metal A) + (decimal fraction of metal B/S.G. of metal B) + (decimal fraction of metal C/S.G. of metal C) +.....D + ....E +.... etc)]. I might mention that this is the most reliable formula for estimating the S.G. of an alloy or a solid blend of 2 or more materials. On this link, you can find the same formula on page 40, middle column.
http://www.platinumguild.com/files/pdf/V3N6W_practical_applications.pdf

Using this chart, you can *estimate* the gold percentage by assuming that these alloys contained these alloying constituents and that their percentages were within the ranges listed in the chart. This is what your refining center obviously did - they made assumptions of the S.G. verses the alloying constituents and the possible resulting gold percentage range and, most likely, they paid you on the low end of this spread. This is a simple, quick, non-destructive, fairly reliable way to buy gold.

The formula for specific gravity = (weight in air)/(weight in air - weight in water)

Your assumption of 48.52 for the weight in water was a poor guess. In this case, the S.G. = (50.713)/(50.713 - 48.52) = 50.713/2.193 = 23.12. For a gold alloy, this is impossible, since the S.G. of pure gold is only 19.3.



Barren Realms,

I worked out the gold content using your weights and S.G. figures, using the equation above. The decimal gold fraction is x in the equation.

S.G. = 96/(96 - 74.5) = 4.465 = 1/[(x/19.3) + (1-x)/2.65]

I worked it twice and came out with a gold content of about 1.45 oz and quartz of 1.63 oz. Pretty close to yours - your is about 8% higher for the gold. I would assume yours must have a little fudge factor in it to make it easier to work. Can you tell me how and why yours works, mathematically? Where did the 1.9 and 3.1 come from? I do realize that you just copied the info off the website you gave. However, there seems to be an 8%, too high problem - about $120 in this case. In my experience, too high estimates can be costly, especially when you're a buyer.


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## goldsilverpro (Jan 3, 2010)

To try and answer this a little better.



Ajmalshaa said:


> I have an alloy of Gold+Copper and did not know that how much amount of copper is mixed with gold.


If the *only metals* are copper and gold, and you know the S.G., you can use the equation,
S.G. = 1/[(x/19.3) + (1-x)/8.93] 
Solve for x to get the decimal fraction of gold in the alloy. The copper decimal fraction = 1-x



Ajmalshaa said:


> My question is that from which formula i can find the Total impurity of an alloy as shown in pic.


You can't for an unknown alloy. The only reason the refining center is able to buy based on S.G. is that they already have a good idea of what metals are in the alloys and their approximate percentages. They surely have a chart to go by that is similar to the one in the attachment in my previous post. In fact, maybe they got the chart from my book - it's been around for 20 years. :lol: 


*Barren Realms 007*,

Ive been thinking further on the post you made. Both my equation and the one from gold-nuggets.org assume that the only things in the mix are pure gold and pure quartz. Actually, the gold likely contains silver and copper. Without doing the math, I would guess that the equation from gold-nuggets.org would produce an error even greater than 8%.

Therefore, unless someone is able to show me the errors of my mathematical ways, I would have to conclude that the formula given on gold-nuggets.org is as worthless as teats on a boar hog and potentially dangerous to one's wallet. I would recommend that the readers of this forum not use that method.

Chris


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## Barren Realms 007 (Jan 3, 2010)

goldsilverpro said:


> Barren Realms,
> 
> I worked out the gold content using your weights and S.G. figures, using the equation above. The decimal gold fraction is x in the equation.
> 
> ...



I had done a quick search on SG here to help find the info for Ajmalshaa and found the link to the site with the formula, so that was how I posted it. I didn't check the formula for accuracy. I figured one of you would do that. :roll: 

It was the only thing I could think of for his question.

Can I take my dunce hat off and get out of the corner for a while today? PLEEEEAAAAAAASSSSSSEEEEEEEE


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## goldsilverpro (Jan 3, 2010)

> Can I take my dunce hat off and get out of the corner for a while today? PLEEEEAAAAAAASSSSSSEEEEEEEE


No problem. I understand that you were trying to help. That formula on that website has come up before. I just try to get people to look before they leap. That's part of my job on this forum. Sometimes, I do it too heavy. I apologize.


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## Barren Realms 007 (Jan 3, 2010)

goldsilverpro said:


> > Can I take my dunce hat off and get out of the corner for a while today? PLEEEEAAAAAAASSSSSSEEEEEEEE
> 
> 
> No problem. I understand that you were trying to help. That formula on that website has come up before. I just try to get people to look before they leap. That's part of my job on this forum. Sometimes, I do it too heavy. I apologize.



You have no need to apologize. I didn't take it as being heavy. It was the only thing I could think of that would possibly answer his question.

If I had wanted to look like a real smarty I would have changed the formula to represent copper and gold, and not the way it was written.

If I don't ask, make a statement or contribute I can't be corrected and can't learn as much. I welcome the corrections any time. I never took chemesrty in school other than basic chem, not saying this is hard subject to learn. If I can get the chemical reaction to click in my brain my learning curve will improve greately.

I will proudly wear my dunce hat!!!!!!! :twisted:


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## Anonymous (Jan 3, 2010)

Thanks guys for ur quick reply .

Guys I am posting the measurement of an alloy which i personally check on Computer
My friend have a software of gold refine.So I get there and do this Procedure.
1) Weight in Air = 2.0780gm
2) Weight in Water = 1.956gm
Then when i press enter it gave me 
Total Impurity = 0.1103
Pure Gold = 1.8490

So Now My question is that how can i find Total impurity as the software gave me.


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## goldsilverpro (Jan 3, 2010)

> Guys I am posting the measurement of an alloy which i personally check on Computer
> My friend have a software of gold refine.So I get there and do this Procedure.
> 1) Weight in Air = 2.0780gm
> 2) Weight in Water = 1.956gm
> ...


The S.G. = 2.0780/(2.0780 - 1.9560) = 2.0780/.1220 = 17.032.

In other words, I think you are asking how to calculate the total impurity level by only knowing the weight in air and the weight in water (and, therefore, knowing the S.G.). *Impossible*, unless you have the added information of what the impurities are and what are their ratios relative to each other. The reason is that each impurity has a different S.G. 

The software is programmed using certain assumptions as to the copper, silver, and, maybe, zinc contents, at specific S.G. levels. Just because the software gave a total impurity of 0.1103, that doesn't mean that it is correct, since the metal percentages in your particular alloy may be different that those built into the software.

Who makes the software? Is it made by the buyer or by an independent?


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## Barren Realms 007 (Jan 3, 2010)

goldsilverpro said:


> *Barren Realms 007*,
> 
> Ive been thinking further on the post you made. Both my equation and the one from gold-nuggets.org assume that the only things in the mix are pure gold and pure quartz. Actually, the gold likely contains silver and copper. Without doing the math, I would guess that the equation from gold-nuggets.org would produce an error even greater than 8%.
> 
> ...



I agree with you GSP, I think they have a lot more uncertainty about what might be in thier mix they are using the formula for. So for our use it would not be fesable to use.

But as far as your other statement about teats on a boar hog you are incorrect. If you are a breader of live stock and you are breading boars for production you never pick a boar with less than 12 teats to put into the breading heard because it follows down the geneology and reduces the number or piglets that a female sow or gilt can raise. :roll:


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## goldsilverpro (Jan 3, 2010)

> But as far as your other statement about teats on a boar hog you are incorrect. If you are a breader of live stock and you are breading boars for production you never pick a boar with less than 12 teats to put into the breading heard because it follows down the geneology and reduces the number or piglets that a female sow or gilt can raise.


Live and learn.


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## Anonymous (Jan 3, 2010)

Barren Realms 007 said:


> goldsilverpro said:
> 
> 
> > *Barren Realms 007*,
> ...



Wouldn't you be counting the teats on the sow not the boar?

jim


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## Barren Realms 007 (Jan 3, 2010)

james122964 said:


> Wouldn't you be counting the teats on the sow not the boar?
> 
> jim



Actually the male and female play a role in it. We never kept any male or female with less than 12 to put into the heard.


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## Palladium (Jan 4, 2010)

goldsilverpro said:


> > But as far as your other statement about teats on a boar hog you are incorrect. If you are a breader of live stock and you are breading boars for production you never pick a boar with less than 12 teats to put into the breading heard because it follows down the geneology and reduces the number or piglets that a female sow or gilt can raise.
> 
> 
> 
> Live and learn.



ROTFL !

You know i think that's the first time we've had a conservation about pigs. :lol:


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## Harold_V (Jan 4, 2010)

goldsilverpro said:


> The software is programmed using certain assumptions as to the copper, silver, and, maybe, zinc contents, at specific S.G. levels. Just because the software gave a total impurity of 0.1103, that doesn't mean that it is correct, since the metal percentages in your particular alloy may be different that those built into the software.


Assuming one could determine the actual volume, _very precisely_, and assuming one had a computer program based on specific gravity and volume, in fact, you can determine ratios of various components, due in part to each having a given specific gravity. Only a proper combination of elements will displace a given volume----and, I agree----it's likely not easy when dealing with unknown elements. In this case, seems to me you need not weigh the sample in air, just in water, and determine it's volume. Am I misguided?

Harold


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## goldsilverpro (Jan 4, 2010)

Harold said:


> In this case, seems to me you need not weigh the sample in air, just in water, and determine it's volume. Am I misguided?


I assume you're thinking of the direct volume measurement method that Samuel and I discussed on another thread. You still need to weigh the object in air to determine the specific gravity.
S.G. = weight (in air) divided by the volume


Ajmalshaa,

I didn't realize that your alloy only contains 2 metals - gold and copper (My apology. I should have re-read your 1st post). The only impurity is copper. In that case, the impurity level can be computed if you know the S.G. of the alloy. You would only get into problems if the total impurity metals were 2 or more, mainly because you don't know the ratio of these metals to each other. As Harold intimated, the accurate measurement of the volume and, therefore, the S.G., is very difficult. However, that is a separate problem that I won't get into. I have covered it a number of times on this forum

For only 2 metals, total - in this case, gold and copper - here's the formula I would use. It utilizes the original formula I gave. In the formula below, FG is the decimal fraction of gold and SGG is it's specific gravity. Likewise, FC is the decimal fraction of copper and SGC is it's specific gravity. SG is the specific gravity of the alloy calculated from your measurements of the weight in air and the weight in water.

Decimal fraction of copper = SGC(SGG - SG)/SG(SGG - SGC)

Using 19.3 for SGG, 8.92 for SGC, and 17.032 for SG, you come up with .1144 for the decimal fraction of copper. From the software, the answer was .1103. A difference could be due to the software using different values for SGG and/or SGC. There is also likely something in the software formula that we don't know about. For example, the specific gravities of various gold/copper alloys could be slightly different than the sums of their parts. Also, in cast alloys, there can be a micro-porosity that can slightly affect the specific gravity. You must also consider that the software is built on using some slightly faulty assumptions. The only ways to determine the true (almost) values are to either assay or refine the material.


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## goldsilverpro (Jan 4, 2010)

Ajmalshaa,

I just got a warning message that something in your 1st post contains malware, of a Warez type. I assume it is the image of the assay report. I edited that post and deleted the image. If that causes a problem, you can hand-type the data that was contained in it.


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## Harold_V (Jan 5, 2010)

goldsilverpro said:


> Harold said:
> 
> 
> > In this case, seems to me you need not weigh the sample in air, just in water, and determine it's volume. Am I misguided?
> ...


Thanks, Chris. That's something I've never attempted.

Harold


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## shadybear (Jan 5, 2010)

So I am Confused! If I weigh a 12 teat boar in water and then in air it will give me
its S.G. :twisted:


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## glorycloud (Jan 5, 2010)

May I humbly suggest that you sedate that boar before attempting to determine it's S.G. in water. :lol:


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## Barren Realms 007 (Jan 5, 2010)

glorycloud said:


> May I humbly suggest that you sedate that boar before attempting to determine it's S.G. in water. :lol:




_*ROFLMAO*_

When we do the SG in water we do it in boiling water, but we always had a problem with contaminents left in the solution. :twisted:


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## Barren Realms 007 (Jan 5, 2010)

shadybear said:


> So I am Confused! If I weigh a 12 teat boar in water and then in air it will give me
> its S.G. :twisted:



If you do the SG test in cold water you might be ok, but if you do it in hot water your test will be inacurate because there will be contaminats left in the water and you measurement will be off.


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## shadybear (Jan 5, 2010)

But if I use hot enough water I should be able to have lunch shortly after


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## Barren Realms 007 (Jan 5, 2010)

shadybear said:


> But if I use hot enough water I should be able to have lunch shortly after




Not shortly after, maybe few hours. But it would taste better BBQ'd.


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## shadybear (Jan 6, 2010)

I think this thread got off topic somehow :twisted: :twisted:


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