nōnāgintā trēs
Well-known member
- Joined
- Dec 5, 2012
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"Above Top Secret" is a websie I frequnt every now and again came up with an interesting way of scraping e-scrap. Since I'm in a good mood I saved it and will share the process here with all of you. If you are familiar or don't like the way this is done thats fine. I'm simply passing on info.
"To dissolve the metal contaminants, we need to use a 50/50 mixture of nitric acid and water. The amount of nitric acid required will be approximately 20 mls mixed with approximately 20 mls of water. Using the plastic pipette, the water is added first followed by the nitric acid.
To help speed the reaction along, the entire glass tube is placed in a bath of boiling water. Periodically, as it cools, replace the bath water with fresh boiling water to keep the reaction going.
There is an immediate strong reaction as copper contaminants immediately start turning the liquid a blue colour.
Also notice the release of brown nitrogen dioxide gas. At this point, walk away from the reaction and do NOT inhale the gas. The reaction can proceed unattended until there is no more bubbling visible.
When the reaction finally stops, add an additional very small quantity (a few mls) of nitric. If bubbling starts up again, then not all the contaminant metals have been dissolved yet and once again, allow the process to continue on its own. If adding further nitric does NOT result in bubbling, then all metal contaminants will have been dissolved leaving behind relatively pure gold.
At this point, you can dilute the blue liquid with water, wait for the gold to settle to the bottom, then carefully pour most of the liquid into another container. Just be careful and don't pour away any of the gold !!
Add some more water to the settled gold to dilute even further any remaining liquid, then let the gold settle again, then carefully pour most of the liquid into another container ... again, DON'T pour away any of the gold.
After repeating the dilute/pour procedure a few times (basically "washing" the gold), we end up with something like this:
The above is the gold obtained from those computer motherboard pins and memory edges.
Note: If you use gold jewelry or any kind of gold/silver mixture, then chances are good that the blue liquid that you've been diluting/pouring off will contain reasonable amounts of dissolved silver. In that case, the silver can also be recovered by using the method I described in my earlier Dummies Guide to EASY silver bullion refining at home as a long term precious metal investment thread.
Having successfully removed almost all of the contaminants leaving the gold in an "almost" pure state, we're now going to process the gold one last time to remove any minute stubborn contaminants and end up with essentially 99.9% pure 24k gold ... woohoo !!
In this final step, we're going to do some "alchemy" ... just like the Ancients used to do !
One of the marvelous properties of gold, and what makes it so sought after and desirable, is that its a metal that that will never tarnish or rust or corrode.
Thats because gold is an extremely nonreactive metal. And because its so nonreactive and stable, non of the common acids will touch it ... not nitric, not hydrochloric, not sulphuric, etc.
So how DO we get the gold to dissolve ?
We'll take advantage of the Ancients knowledge of applied alchemy when they somehow discovered that a mixture of 1 part nitric and 3 parts hydrochloric performed the seemingly impossible ... it dissolved gold !
Because this combination of acids had the "power" to dissolve gold, which they considered to be the most "regal or noble" of metals, they gave it the special name of "Royal Water" ... or as they called it in Latin ... "Aqua Regia".
So, transfer the "washed" gold into one of the glass tubes and add a 1:3 mix of nitric and hydrochloric acids.
With the quantity of gold in this tutorial, using the plastic pipette, I added 5 drops of nitric and 15 drops of hydrochloric making a 1:3 mixture of Aqua Regia.
Immediately the gold starts to dissolve and the liquid starts to bubble and turn a nice yellow colour. This is a good sign that almost all contaminants have been removed previously. If the liquid has a blue or green tinge, then that means some copper must still be present with the gold.
Again, to speed up the reaction, we'll place the glass tube into a bath of boiling water.
Allow the reaction to continue until all the gold has dissolved. If the reaction stops and some gold still remains, then add a further small quantity of "Aqua Regia".
Ok, all the gold has dissolved leaving a yellow liquid behind ... for all intents and purposes, this yellow liquid is "liquid gold" ... so be very careful and DON'T spill any !
This yellow liquid may or not look slightly cloudy but either way, it won't do any harm to filter it.
So create a filter as shown here:
We're going to pour the yellow liquid through the filter and into a clean, empty glass tube.
Now I can't stress this part enough ... make sure that you have scrubbed and washed this glass tube until it's absolutely squeaky clean. The reason being that shortly, we'll be causing the dissolved gold to be "dropped" out of solution as a dark brown material that will settle on the bottom of the jar.
If the jar is NOT squeaky clean, some of the gold, as it drops out of solution, could stick to the sides of the glass jar giving it a very fine gold coating, similar to the fine silver coating on the back of a mirror. Then you'll waste time and effort in scraping this layer off to recover the gold in it.
After all the yellow liquid has been poured into and passed through the filter, using the water spray bottle, spray the inside of the filter to ensure that every last bit of yellow liquid containing the gold has been washed through the filter and into the glass bottle.
Ok, now dilute the yellow liquid with an equal volume of water.
We should be looking at something like the following:
We're now almost ready to precipitate or "drop" the gold back out of the yellow liquid but just before we do that, we need to completely neutralize any remaining traces of nitric acid that may still remain in the yellow liquid. The reason for this is simply that if we start to "drop" the gold in the form of a brown sediment, as soon as any of it appears, it will be immediately attacked by the remaining nitric/hydrochloric acid in the yellow solution and dissolved once again. So to prevent the "gold sediment" from going back into solution, where we don't want it to go, a simple way to prevent this is to first use urea to neutralize the nitric ... then successfully "drop" the sediment where it will eventually settle at the bottom of the glass jar.
I recommend using just a pinch of urea at a time. When added to the yellow liquid, you should notice bubbles being created by the urea. This is a sign that nitric acid is being neutralized. As the urea is used up, continue adding smaller and smaller amounts until there is no more bubbling to be seen ... at this point, the remaining nitric acid has been completely neutralized and we can proceed with "dropping" the gold back out of solution as a brown sediment."
"To dissolve the metal contaminants, we need to use a 50/50 mixture of nitric acid and water. The amount of nitric acid required will be approximately 20 mls mixed with approximately 20 mls of water. Using the plastic pipette, the water is added first followed by the nitric acid.
To help speed the reaction along, the entire glass tube is placed in a bath of boiling water. Periodically, as it cools, replace the bath water with fresh boiling water to keep the reaction going.
There is an immediate strong reaction as copper contaminants immediately start turning the liquid a blue colour.
Also notice the release of brown nitrogen dioxide gas. At this point, walk away from the reaction and do NOT inhale the gas. The reaction can proceed unattended until there is no more bubbling visible.
When the reaction finally stops, add an additional very small quantity (a few mls) of nitric. If bubbling starts up again, then not all the contaminant metals have been dissolved yet and once again, allow the process to continue on its own. If adding further nitric does NOT result in bubbling, then all metal contaminants will have been dissolved leaving behind relatively pure gold.
At this point, you can dilute the blue liquid with water, wait for the gold to settle to the bottom, then carefully pour most of the liquid into another container. Just be careful and don't pour away any of the gold !!
Add some more water to the settled gold to dilute even further any remaining liquid, then let the gold settle again, then carefully pour most of the liquid into another container ... again, DON'T pour away any of the gold.
After repeating the dilute/pour procedure a few times (basically "washing" the gold), we end up with something like this:
The above is the gold obtained from those computer motherboard pins and memory edges.
Note: If you use gold jewelry or any kind of gold/silver mixture, then chances are good that the blue liquid that you've been diluting/pouring off will contain reasonable amounts of dissolved silver. In that case, the silver can also be recovered by using the method I described in my earlier Dummies Guide to EASY silver bullion refining at home as a long term precious metal investment thread.
Having successfully removed almost all of the contaminants leaving the gold in an "almost" pure state, we're now going to process the gold one last time to remove any minute stubborn contaminants and end up with essentially 99.9% pure 24k gold ... woohoo !!
In this final step, we're going to do some "alchemy" ... just like the Ancients used to do !
One of the marvelous properties of gold, and what makes it so sought after and desirable, is that its a metal that that will never tarnish or rust or corrode.
Thats because gold is an extremely nonreactive metal. And because its so nonreactive and stable, non of the common acids will touch it ... not nitric, not hydrochloric, not sulphuric, etc.
So how DO we get the gold to dissolve ?
We'll take advantage of the Ancients knowledge of applied alchemy when they somehow discovered that a mixture of 1 part nitric and 3 parts hydrochloric performed the seemingly impossible ... it dissolved gold !
Because this combination of acids had the "power" to dissolve gold, which they considered to be the most "regal or noble" of metals, they gave it the special name of "Royal Water" ... or as they called it in Latin ... "Aqua Regia".
So, transfer the "washed" gold into one of the glass tubes and add a 1:3 mix of nitric and hydrochloric acids.
With the quantity of gold in this tutorial, using the plastic pipette, I added 5 drops of nitric and 15 drops of hydrochloric making a 1:3 mixture of Aqua Regia.
Immediately the gold starts to dissolve and the liquid starts to bubble and turn a nice yellow colour. This is a good sign that almost all contaminants have been removed previously. If the liquid has a blue or green tinge, then that means some copper must still be present with the gold.
Again, to speed up the reaction, we'll place the glass tube into a bath of boiling water.
Allow the reaction to continue until all the gold has dissolved. If the reaction stops and some gold still remains, then add a further small quantity of "Aqua Regia".
Ok, all the gold has dissolved leaving a yellow liquid behind ... for all intents and purposes, this yellow liquid is "liquid gold" ... so be very careful and DON'T spill any !
This yellow liquid may or not look slightly cloudy but either way, it won't do any harm to filter it.
So create a filter as shown here:
We're going to pour the yellow liquid through the filter and into a clean, empty glass tube.
Now I can't stress this part enough ... make sure that you have scrubbed and washed this glass tube until it's absolutely squeaky clean. The reason being that shortly, we'll be causing the dissolved gold to be "dropped" out of solution as a dark brown material that will settle on the bottom of the jar.
If the jar is NOT squeaky clean, some of the gold, as it drops out of solution, could stick to the sides of the glass jar giving it a very fine gold coating, similar to the fine silver coating on the back of a mirror. Then you'll waste time and effort in scraping this layer off to recover the gold in it.
After all the yellow liquid has been poured into and passed through the filter, using the water spray bottle, spray the inside of the filter to ensure that every last bit of yellow liquid containing the gold has been washed through the filter and into the glass bottle.
Ok, now dilute the yellow liquid with an equal volume of water.
We should be looking at something like the following:
We're now almost ready to precipitate or "drop" the gold back out of the yellow liquid but just before we do that, we need to completely neutralize any remaining traces of nitric acid that may still remain in the yellow liquid. The reason for this is simply that if we start to "drop" the gold in the form of a brown sediment, as soon as any of it appears, it will be immediately attacked by the remaining nitric/hydrochloric acid in the yellow solution and dissolved once again. So to prevent the "gold sediment" from going back into solution, where we don't want it to go, a simple way to prevent this is to first use urea to neutralize the nitric ... then successfully "drop" the sediment where it will eventually settle at the bottom of the glass jar.
I recommend using just a pinch of urea at a time. When added to the yellow liquid, you should notice bubbles being created by the urea. This is a sign that nitric acid is being neutralized. As the urea is used up, continue adding smaller and smaller amounts until there is no more bubbling to be seen ... at this point, the remaining nitric acid has been completely neutralized and we can proceed with "dropping" the gold back out of solution as a brown sediment."
