Preparation for refinement

[Yggdrasil]

Hello!

Yesterday I used sulfamic acid instead of urea for the first time, the solution fizzed very weakly, then when it stopped, I filtered it again.
It turned out to be such a fine gold powder that I have never seen before, its color became slightly dark. I made the mistake of not re-dissolving it in AR, I melted it and the color turned out ugly. Unfortunately, I can stand it again today, my solution is also strange, the gold precipitated out of it, there is a lighter band on top, and the color is brownish below.
I tested it, there is no more gold in it when dissolved.

I don't have sulfuric acid, can I wash the gold dust in hydrochloric acid and then in distilled water?

The size of each grain is a function of how clean and how concentrated the solution is before dropping.
Clean, concentrated solutions drop large well agglomerated grains.

And washing with HCl and water is always recommended.
Wash until no more color remains in the wash water.
Then water wash until the wash water is neutral.

 

[Alexander_Hun]

The size of each grain is a function of how clean and how concentrated the solution is before dropping.
Clean, concentrated solutions drop large well agglomerated grains.

And washing with HCl and water is always recommended.
Wash until no more color remains in the wash water.
Then water wash until the wash water is neutral.

I see, there is no need to worry that gold may dissolve when washing in hydrochloric acid?
Yes, I received amazingly fine powder, I thought it was only a few grams, it turned out to be 15 grams. Although I think there is little knowledge of the raw material and how much it usually contains.
But gold can cause surprises

 

[kurtak]

For separating Lead Chloride from Silver Chloride just wash with water.
Led chloride dissolves in water Silver Chloride don't.

There needs to be a bit of correction/clarification here

Lead chloride does NOT dissolve in COLD water - BUT - it is VERY soluble in HOT water

So - if you have lead chloride in your silver chloride you MUST use HOT water to wash the lead chloride out of the silver chloride - then when the HOT water washes cool back down the lead chloride will precipitate back out

So - if you have PbCl in your AgCl you can use this fact to test to insure all the PbCl has been washed out of the AgCl --- after (each) HOT water wash cool the hot water wash down - if the wash water turns cloudy (&/or settles a white precipitate) after cooling you need to do another HOT water wash

Kurt

 

[kurtak]

And washing with HCl and water is always recommended.
Wash until no more color remains in the wash water.
Then water wash until the wash water is neutral.

I see, there is no need to worry that gold may dissolve when washing in hydrochloric acid?
Yes, I received amazingly fine powder, I thought it was only a few grams, it turned out to be 15 grams. Although I think there is little knowledge of the raw material and how much it usually contains.
But gold can cause surprises

Again there needs to be some clarification here

After dropping your gold the FIRST wash should be to do a water wash in order to get the chem washed out - this can & will take several washes (3 - 5) so after the third was wash you want to test for Ph - if Ph is still showing acidic wash again

Then - once the water washes show Ph neutral is when you want to start with the HCl washing - the HCl washing is done to wash out any base metals that dragged down when you precipitated the gold (such as nickel iron etc.) this again can take 3 -5 washes - you know any base metal contamination is washed out of the gold sponge/powder when the HCl wash does not change color & remains clear

You then again need water wash to get the HCl washed out of the gold sponge/powder - you know these water washes are done when it test Ph neutral

So the washing process is - 1) water wash - 2) HCl wash - 3) water wash --- not just - 1) HCl wash - 2) water wash

Not boil but hot washes yes.

I disagree - I ALWAYS wash my gold by bring the washes to a "simmer" boil - the reason for that is by bring the wash to a boil (simmering boil) is that the kinetic energy of the boil gets the wash "into" the sponge/powder thereby forcing out the chem (water washes) as well as base metal contaminates (HCl wash) trapped in the gold sponge/powder

Make sure you do the washing with a watch glass on top of the beaker - otherwise the boiling washes will erupt/shoot gold sponge/powder out the top of the beaker

Depending on how much gold sponge/powder I have in my beaker when washing I bring the wash to a simmer boil & let it boil for at least 1 minute (if its a gram or 2) & up to 10 minutes if its an ozt or more - so that the kinetic energy has time to force the chem/contaminates "out" of the gold sponge/powder

Kurt

 

[kurtak]

I see, there is no need to worry that gold may dissolve when washing in hydrochloric acid?

It is possible (meaning you may - or not) dissolve gold if you go right to a HCl wash after dropping your gold

That is why (as I posted) you FIRST want to do a water wash - the HCl wash - then another water wash

Kurt

 

[Yggdrasil]

There needs to be a bit of correction/clarification here

Lead chloride does NOT dissolve in COLD water - BUT - it is VERY soluble in HOT water

So - if you have lead chloride in your silver chloride you MUST use HOT water to wash the lead chloride out of the silver chloride - then when the HOT water washes cool back down the lead chloride will precipitate back out

So - if you have PbCl in your AgCl you can use this fact to test to insure all the PbCl has been washed out of the AgCl --- after (each) HOT water wash cool the hot water wash down - if the wash water turns cloudy (&/or settles a white precipitate) after cooling you need to do another HOT water wash

Kurt

I was not aware that water have to be hot to dissolve Lead Chloride.
Good point.
This was a reply to Murat that claimed the Lead Sulfate was soluble.
But I found that odd so I presented an alternative route.

 

[Yggdrasil]

Again there needs to be some clarification here

After dropping your gold the FIRST wash should be to do a water wash in order to get the chem washed out - this can & will take several washes (3 - 5) so after the third was wash you want to test for Ph - if Ph is still showing acidic wash again

Then - once the water washes show Ph neutral is when you want to start with the HCl washing - the HCl washing is done to wash out any base metals that dragged down when you precipitated the gold (such as nickel iron etc.) this again can take 3 -5 washes - you know any base metal contamination is washed out of the gold sponge/powder when the HCl wash does not change color & remains clear

You then again need water wash to get the HCl washed out of the gold sponge/powder - you know these water washes are done when it test Ph neutral

So the washing process is - 1) water wash - 2) HCl wash - 3) water wash --- not just - 1) HCl wash - 2) water wash


I disagree - I ALWAYS wash my gold by bring the washes to a "simmer" boil - the reason for that is by bring the wash to a boil (simmering boil) is that the kinetic energy of the boil gets the wash "into" the sponge/powder thereby forcing out the chem (water washes) as well as base metal contaminates (HCl wash) trapped in the gold sponge/powder

Make sure you do the washing with a watch glass on top of the beaker - otherwise the boiling washes will erupt/shoot gold sponge/powder out the top of the beaker

Depending on how much gold sponge/powder I have in my beaker when washing I bring the wash to a simmer boil & let it boil for at least 1 minute (if its a gram or 2) & up to 10 minutes if its an ozt or more - so that the kinetic energy has time to force the chem/contaminates "out" of the gold sponge/powder

Kurt

I usually roast between acids so there is no need for the water washes first.

 

[Yggdrasil]

I see, there is no need to worry that gold may dissolve when washing in hydrochloric acid?
Yes, I received amazingly fine powder, I thought it was only a few grams, it turned out to be 15 grams. Although I think there is little knowledge of the raw material and how much it usually contains.
But gold can cause surprises

No as long as HCl is alone it will not touch the Gold.
That is why roasting is recommended between different acids.

 

[Alexander_Hun]

I'm in the process of unraveling it all again, I hammered it flat and cut the gold into strips. Thanks for all the help

 

[kurtak]

One more side note; - if your gold drop comes down as a FINE powder - by bringing the washes to a simmer boil the boiling will help to cause FINE powder particles to "floc" together into larger sponge like particles

It should look like this after the (simmer boiling) washes

Kurt

 

[Alexander_Hun]

One more side note; - if your gold drop comes down as a FINE powder - by bringing the washes to a simmer boil the boiling will help to cause FINE powder particles to "floc" together into larger sponge like particles

It should look like this after the (simmer boiling) washes

Kurt

In water or hydrochloric acid? I noticed that after boiling with hydrochloric acid, the powder becomes much larger

 

[Alexander_Hun]

Continuation tomorrow, you will never melt gold again if the color is not good for some reason. If I had dissolve it again, about 30 seconds, so it was 8 hours.... It looks better now

 

[Golddigger76]

We all learn these kinds of lessons from experience but the more you do refining projects the easier it becomes to make the right choice of what needs to be done next.

This is something that you now fully understand and you will go ahead and refine a second time now that you made the mistake of melting your gold powder after one refine.

I'm not saying that it is impossible to get 999.9 with one refine but it is unlikely and gold powders will dissolve way faster than a button or bar.

Great looking gold chloride by the way !!!!

 

[kurtak]

I usually roast between acids so there is no need for the water washes first.

No as long as HCl is alone it will not touch the Gold.
That is why roasting is recommended between different acids.

I think you have two different processes confused here

1) pre-treatment of material before refining to remove base metals ---2) washing your gold powder/sponge

Example; - pins removed from CBs wherein you would want to use HCl to remove the tin solder & then nitric to get rid of the copper/brass to recover the foils - which then go to refining (AR)

In this case then - between the HCl treatment & nitric treatment yes you want to roast the pins after the HCl treatment because even after giving the pins a good water washing there is likely to still be at least "traces" of HCl in/on the pins

So - if you don't roast the pins (to drive of trace chlorides) before going to the nitric treatment you are likely to create a weak AR when you treat them with nitric to get rid of the copper/brass so that weak AR is likely to dissolve at least some of the gold plating in the process of getting rid of the copper/brass --- therefore the recommendation to roast between the 2 different acid treatments

This holds true in any case where you use different acids as pre-treatments to remove base metals - such as an HCl leaching of IC chip ash to remover tin/aluminum etc. - then nitric to leach copper etc. - then AR to leach gold bond wires

In both of those examples you only need to be concerned with roasting between the HCl treatment & the nitric treatment so as not to create a weak AR & dissolve gold before you are ready to dissolve gold

So the process is as follows -----------

1) pre-treat with HCl to remove chloride soluble metals (tin aluminum etc.)- wash material to get rid of most HCl leach - some traces of chloride are likely to remain - so ------

2) roast to drive off chlorides so as not to create weak AR in next step

3) pre-treat with nitric to remove nitrate soluble metals (copper silver etc.) wash material to get rid of most nitrate leach - some traces of nitrate are likely to remain

4) leach with AR to dissolve PMs (gold PGMs)

5) no need to roast between step 3 & step 4 as the intent of step 4 is to make AR so trace nitrate after step 3 doesn't matter

So - if you are using different acids - as pre-treatments - before the actual leaching of your PMs - then yes - you certainly want to roast between the different pre-treatments

No as long as HCl is alone it will not touch the Gold.
That is why roasting is recommended between different acids.

Here we are talking about washing your gold powder/sponge after precipitation of the gold so there is no need to roast before doing the HCl wash & that is because you are really not switching between acids (chlorides & nitrates) --- in other words the AR from which you precipitated the gold is in fact a chloride solution - the nitrate you used in the AR has ether been "used up" by dissolving the metals - or removed by de-NOxing (before precipitation) thereby leaving you with a chloride solution

So - because the solution you have after dropping your gold is a chloride solution - there is no need to roast the gold powder/sponge before washing the powder/sponge with HCl because both the solution the gold was precipitated from is a chloride solution as is the HCl you are washing the powder/sponge with

You can get away without the first water wash - but you will use more HCl because you are using acid to wash out acid before the (wash) acid becomes effective at dissolving any base metal drag down in the gold drop - which is why water washing (to get the AR acid out) is recommended before going to the HCl washing

The washing procedure I posted yesterday (water washing - HCl washing - water washing) is the "standard" washing procedure & no roasting is needed in that process because it is an all chloride situation

When washing your gold sponge/powder the ONLY time you need to concern yourself with roasting is if you intend to do a nitric wash after the HCl wash - AND - the simmer boiling is also the recommendation when doing the washing as it induces the kinetic energy that makes the washing effective

You can get away without doing the simmer boil washes - BUT - that requires using a vacuum filtering set up which is another story/process

Kurt

 

[Alexander_Hun]

I think you have two different processes confused here

1) pre-treatment of material before refining to remove base metals ---2) washing your gold powder/sponge

Example; - pins removed from CBs wherein you would want to use HCl to remove the tin solder & then nitric to get rid of the copper/brass to recover the foils - which then go to refining (AR)

In this case then - between the HCl treatment & nitric treatment yes you want to roast the pins after the HCl treatment because even after giving the pins a good water washing there is likely to still be at least "traces" of HCl in/on the pins

So - if you don't roast the pins (to drive of trace chlorides) before going to the nitric treatment you are likely to create a weak AR when you treat them with nitric to get rid of the copper/brass so that weak AR is likely to dissolve at least some of the gold plating in the process of getting rid of the copper/brass --- therefore the recommendation to roast between the 2 different acid treatments

This holds true in any case where you use different acids as pre-treatments to remove base metals - such as an HCl leaching of IC chip ash to remover tin/aluminum etc. - then nitric to leach copper etc. - then AR to leach gold bond wires

In both of those examples you only need to be concerned with roasting between the HCl treatment & the nitric treatment so as not to create a weak AR & dissolve gold before you are ready to dissolve gold

So the process is as follows -----------

1) pre-treat with HCl to remove chloride soluble metals (tin aluminum etc.)- wash material to get rid of most HCl leach - some traces of chloride are likely to remain - so ------

2) roast to drive off chlorides so as not to create weak AR in next step

3) pre-treat with nitric to remove nitrate soluble metals (copper silver etc.) wash material to get rid of most nitrate leach - some traces of nitrate are likely to remain

4) leach with AR to dissolve PMs (gold PGMs)

5) no need to roast between step 3 & step 4 as the intent of step 4 is to make AR so trace nitrate after step 3 doesn't matter

So - if you are using different acids - as pre-treatments - before the actual leaching of your PMs - then yes - you certainly want to roast between the different pre-treatments


Here we are talking about washing your gold powder/sponge after precipitation of the gold so there is no need to roast before doing the HCl wash & that is because you are really not switching between acids (chlorides & nitrates) --- in other words the AR from which you precipitated the gold is in fact a chloride solution - the nitrate you used in the AR has ether been "used up" by dissolving the metals - or removed by de-NOxing (before precipitation) thereby leaving you with a chloride solution

So - because the solution you have after dropping your gold is a chloride solution - there is no need to roast the gold powder/sponge before washing the powder/sponge with HCl because both the solution the gold was precipitated from is a chloride solution as is the HCl you are washing the powder/sponge with

You can get away without the first water wash - but you will use more HCl because you are using acid to wash out acid before the (wash) acid becomes effective at dissolving any base metal drag down in the gold drop - which is why water washing (to get the AR acid out) is recommended before going to the HCl washing

The washing procedure I posted yesterday (water washing - HCl washing - water washing) is the "standard" washing procedure & no roasting is needed in that process because it is an all chloride situation

When washing your gold sponge/powder the ONLY time you need to concern yourself with roasting is if you intend to do a nitric wash after the HCl wash - AND - the simmer boiling is also the recommendation when doing the washing as it induces the kinetic energy that makes the washing effective

You can get away without doing the simmer boil washes - BUT - that requires using a vacuum filtering set up which is another story/process

Kurt

Hello! My biggest problem is what I already wrote in another post, a lot of white sludge is produced when I dissolve gold-plated things in nitric acid. It probably contains a lot of bronze, which contains a lot of tin, I can't do anything about it, it clogs the filters and mixes with the gold-plated foils. If I pour hydrochloric acid on it, it will turn brownish, but I am afraid that this will also dissolve the gold-plated foil if there is any nitric acid left in it.

 

[Yggdrasil]

Hello! My biggest problem is what I already wrote in another post, a lot of white sludge is produced when I dissolve gold-plated things in nitric acid. It probably contains a lot of bronze, which contains a lot of tin, I can't do anything about it, it clogs the filters and mixes with the gold-plated foils. If I pour hydrochloric acid on it, it will turn brownish, but I am afraid that this will also dissolve the gold-plated foil if there is any nitric acid left in it.

If it is Metastannic acid, roast it well and dissolve in HCl.
Filter out the Gold and dissolve.

 

[kurtak]

If it is Metastannic acid, roast it well and dissolve in HCl.
Filter out the Gold and dissolve.

Yes - this is another example where roasting is needed

Kurt

 

[Alexander_Hun]

What do you mean by roasting? Do I put it in a beaker and bake it completely dry?

 

[kurtak]

Hello! My biggest problem is what I already wrote in another post, a lot of white sludge is produced when I dissolve gold-plated things in nitric acid. It probably contains a lot of bronze, which contains a lot of tin, I can't do anything about it, it clogs the filters and mixes with the gold-plated foils. If I pour hydrochloric acid on it, it will turn brownish, but I am afraid that this will also dissolve the gold-plated foil if there is any nitric acid left in it.

In this situation - the metastannic acid (sometimes called tin paste) from dissolving bronze with nitric needs roasting (as Yaggdrasil said) & yes if you add HCl to it - without roasting it will more then likely dissolve gold because it is next to impossible to get all the nitric washed out AND the HCl will do NOTHING to dissolve the tin paste away

So - after washing the tin paste/gold foil mix/mess as good as possible (to remove as much copper nitrate as possible) you want to roast the tin paste/gold foil mix/mess

This does two things

1) it drives of the nitrates so that HCl will not make AR that dissolves gold before you are ready to dissolve gold (the tin has not been removed yet)

2) the roasting converts the tin paste to actual tin (or tin oxide) which will then dissolve in HCl leaving you with (at least) cleaner gold foils

Depend on the amount of tin paste &/or how complete the conversion of tin paste to tin is during roasting you may have to do the process more then once

in other words --- roast - leach with HCl - roast again - leach with HCl again

Kurt

 

[Yggdrasil]

What do you mean by roasting? Do I put it in a beaker and bake it completely dry?

Use a low ceramic vessel, melting dish or similar.
Or a frying pan, not important.
Heat it until it glows in a low red for some time.
It will transform the Metastannic acid to Tin Oxide which will dissolve in HCl