Link between SMB quantity and gold quantity

[Uciocciu]

Hi,

I just begin to take information on PM refining. I'd like to ask a simple question.

Is there a link between the quantity of SMB that is poured (in gram) and the quantity of gold that we hope to obtain (in grams)? If so, is there a mathematical rule, such as 1 gram of SMB for 1 gram of expected gold?

Thank you in advance,

U ciocciu

 

[nickvc]

I must admit I have never used smb but with any precipitant if your testing your solution using stannous you always know if you have any gold left in solution. Getting used to regular testing is useful and will keep you informed as to where your gold is.

 

[Uciocciu]

Thank you so much for your response !

Using stannous chloride is the best solution indeed.

But is the SMB quantity you drop based on your assessment of the gold quantity you expect ?

Is there any link between SMB quantity and gold quantity ?

 

[anachronism]

There is no link at all.

You use as much as is required to get a stannous reading that shows you have no gold.

Test - test - test.

 

[FrugalRefiner]

If you do a search using the words SMB weight gold weight, you'll find plenty of links. The generally quoted ratio is to use about the same weight of SMB as the weight of gold you expect, but it's just a general guideline. It depends on many things. If there is excess nitric, some of the SMB will be consumed reducing the gold which immediately goes back into solution. Other metals in a dirty solution will use some. So it's just a general guideline. You can start by adding 80% of what you expect to need, then test. Add more as needed till the solution tests negative.

Dave

 

[Lino1406]

(Edited)
SMB:gold 1:1 w/w
Copperas:gold 6:1
here is citation from Amen "You will need about fifteen ounces of copperas to recover two and a half ounces of gold"

 

[anachronism]

SMB:gold 1:1
Copperas:gold 5:1

Absolute rubbish.

 

[g_axelsson]

SMB:gold 1:1
Copperas:gold 5:1

Absolute rubbish.

In what way is that rubbish? What are the correct numbers then?

Of course there is a link or a proportion between the amount of precipitant used and the amount of gold precipitated. For SMB I've also heard the 1:1 based on weight, but I don't recall I have ever seen a number for copperas before.
It should be easily calculated from the chemical equations if anyone is interested enough.

In real life various side-reactions will affect the result to a certain degree. Testing is the real way to be sure you have added enough.

Göran

 

[anachronism]

If you are going to say SMB: Gold = 1:1 then you have to provide a set of circumstances where that equation prevails.

So - go for it guys. Provide us with that complete set of conditions:

Temperature
Liquid volume
Shape of container
Liquid type
Liquid viscosity
Gold Chloride concentration
Contaminants present

In reality 1:1 does not happen so stoichiometry plays absolutely no part.

Since I first mentioned this on this forum and elsewhere I have been contracted by no less than five people who have taken this incorrect 1:1 link to mean that they calculate their gold return, add the corresponding amount of SMB, collect the gold that's dropped and that it- they throw the solution out.

Now whilst it's easy to say they are misinterpreting things and not following correct process if five people have been doing that then I'd suggest it's as much in how the information is presented as in the way they are doing it.

So I suggest, since people take things too literally that we break that link between SMB:gold and tell it how it really is - namely you use as much SMB as is required to drop all your gold and give a negative stannous test. <<< This IS the reality and I would challenge anyone out there to prove different. 8) 8)

Jon

 

[Shark]

According to Hoke, for copperas



In another vessel, dissolve in warm water about a pound of green
copperas for each 50 pennyweight of fine gold that you expect to
recover. Use fresh green copperas, with about a quart of water to a
pound. Add a little hydrochloric acid, enough to make the copperas
solution a clear green.

I have used that exactly as she describes but I had to make small adjustments to get the negative test using it. While I know very little of the chemistry behind much of it, I do understand the importance of testing as I work through the processes.

A questions on the subject in hopes of learning a bit more about it:
How does heat play into the factor of using the precipitant?

 

[anachronism]

A questions on the subject in hopes of learning a bit more about it:
How does heat play into the factor of using the precipitant?

Hi shark

If you are using SMB the active ingredient is the S02 that is produced. The hotter the solution, the quicker the reaction happens and more of the S02 comes out of the solution into the air before it is used. As such the hotter the solution, the more you need to use because of wastage.

 

[Shark]

The past few months I have been heating my solutions to make my drops and it seems to produce cleaner gold drops for me when using SMB. I have not tried the copperas with heat yet, but I want to see what difference it makes as well. Is there a point that raising the temperature higher offers no benefit? I have been doing pretty good at around 125*F for both the auric chloride and the SMB in solution.

 

[anachronism]

I use caked SMB for my drops as per Deano's recommendation rather than pre-dissolving it. That's another procedural difference that has a bearing on claimed percentages.

With Ferrous Sulphate I do drop warm because I agree it seems to make a positive difference. The only danger with that is when you don't quite denox properly and it boils over. Schoolboy mistake of course but it doesn't hurt to share. 8) 8)

 

[g_axelsson]

I like to still push the 1:1 number for SMB, not that it is an exact ration but because newbies often dump huge amount of chemicals into their reactions without any thought of what's reasonable. If you expect 10g of gold then don't add half a kilo of SMB to your solution and then wonder if it was enough. The number is a reasonable amount to start with, if it doesn't produce gold then there is something wrong and you need to deal with it before just adding more SMB.

Remaining oxidizer, out-gassing and side reactions (Cu++ -> Cu+ for example) will throw the numbers off so there is no way you could just run blindly and skip testing and a stock pot will always be a good insurance for not loosing any values.

I don't have time right now but it would be fun to run a small test, dissolve some gold, filter and then add a small amount of SMB without precipitating all of it. Just to see how much gold actually dropped. It's an easy test and could probably be done with just a few hours work.
I'll try to remember this one and get back to it when time permits.

Refining reminds me a lot of the two foundation laws of astronomy :
1. One is close to ten.
2. One is a lot less than ten.

Göran

 

[anachronism]

That's completely illogical Goran. 8) 8)

I'd still like to push a patently incorrect figure even though I've shown you a clear reason not to do this, that has harmed peoples' refining? Interesting concept old friend.

Next you'll be telling me it takes 1 cc of Nitric and 3 cc of HCl to dissolve a gramme of gold.....

:lol: :lol:

Jon

 

[Lino1406]

Some parachronistic information. Comparing the data below with actual recommendations above show a safety factor of 1.4

 

[Shark]

Some parachronistic information

I admit, I had to go look up that definition.

 

[g_axelsson]

Wonderful! Tanks Lino!

Göran

 

[Geo]

Just a side note. Overuse of SMB will cause several problems for the beginner. The main problem is gold powder that will not settle. The SMB is decomposed by the acid in the solution producing SO2. The small bubbles attract metallic gold on the outside of the bubble. The bubble is consumed in the conversion and the gold settles to the bottom. If the gold is depleted and there is still SO2 present in the solution, the remaining bubbles will attract whatever gold is left. The bubbles buoyancy tries to take it to the surface but the weight of the gold keeps it from rising to the surface. So now there are many small bubbles in the solution with tiny amounts of gold metal that neither rises or settles. The small gold "floaters" on the surface is bubbles that manage to make to the surface and burst depositing it's gold on the surface where surface tension keeps the gold from settling. The solution to this problem is to heat the solution. Warm to hot solutions expels gas faster than a cold solution. The excess SO2 is expelled and the suspended gold is allowed to settle. Be aware that warming the solution with the precipitated gold in the container can result in left over nitrates redissolving some of the precipitated gold. Hot reagents are more reactive than cold reagents. Always test after heating and cooling.

 

[anachronism]

Wonderful! Tanks Lino!

Göran

For a table that shows "theoretical" data with no corroboration? Come on guys - is this the best rebuttal and chemistry you can give the theory I have posited?