AR Process Carat Jewellery

[cejohnsonsr1]

I try use minimal nitric as possible, I do not have sulphuric acid on hand either.

Drain cleaner.

 

[nickton]

I always thought one uses copperas when inquarting. It looks like I'll have to read up on this again.

 

[FigiMon]

Drain cleaner.

Very hard to find sulphuric acid in general in Europe and never as drain cleaner.

 

[FigiMon]

I always thought one uses copperas when inquarting. It looks like I'll have to read up on this again.

I believe the usual advice is to use different reducing agents in the first and second refining. I generally use ferrous sulphate for both though since it is so easily available and cheap here.

Also if there is free nitric left in the solution the ferrous sulphate will complex with it. Free nitric with SMB can give you a runaway reaction where the fine gold redissolves and you risk a boilover.

 

[cejohnsonsr1]

Most drain cleaners are just sulphuric acid. For the purpose of removing lead, it only takes a few drops. SMB is an exothermic reaction. It will remove excess nitric, but if you have so much excess nitric that a runaway is possible, you have problems with your process that no method of precipitation is going to solve.

 

[cejohnsonsr1]

I always thought one uses copperas when inquarting. It looks like I'll have to read up on this again.

Copperas (ferras sulphate) is used to precipitate gold from solution after digestion. Inquartation is the process of reducing the karat weight of scrap gold to about 6 (or 25% or 1/4) to facilitate the removal of metals that are not gold. These 2 processes may or may not be used in conjunction, but are unrelated and independent of each other.

 

[FigiMon]

Most drain cleaners are just sulphuric acid. For the purpose of removing lead, it only takes a few drops. SMB is an exothermic reaction. It will remove excess nitric, but if you have so much excess nitric that a runaway is possible, you have problems with your process that no method of precipitation is going to solve.

Most drain cleaners in the US perhaps, in Europe they are all NaOH.

It really takes very little excess nitric to get a very vigorous reaction with the fine gold. I am a bit lazy and generally will not bother with getting rid of excess nitric. Reducing with SMB can then be problematic since as you say it is an exothermic reaction. With ferrous sulphate the only thing that happens is you have to use more and the solution goes really really dark.

 

[Yggdrasil]

Most drain cleaners are just sulphuric acid. For the purpose of removing lead, it only takes a few drops. SMB is an exothermic reaction. It will remove excess nitric, but if you have so much excess nitric that a runaway is possible, you have problems with your process that no method of precipitation is going to solve.

In our country most are Sodium/Potassium Hydroxide or a mix of these.
There are Sulphuric if one looks the right places.
Battery acid is plenty good enough for dropping the lead though.

Edit to add.
Figimon beat me to it

 

[Martijn]

Most drain cleaners in the US perhaps, in Europe they are all NaOH.

Sorry, but thats not true.

Ontstopper (dutch for drain cleaner) 96%, bought this year online.

 

[FigiMon]

Sorry, but thats not true.
View attachment 57791
Ontstopper (dutch for drain cleaner) 96%, bought this year online.

Wow!

And I have been to the Netherlands four times in the last year alone

 

[Martijn]

Due to explosives and drugs precursor laws you do need a permit unfortunately. No longer available for private persons.
This where I got it: Werken met Merken - Voor 22.00 uur besteld, morgen in huis!
They sell about all the acids you need. If you have a registered buisiness.
There are a lot more suppliers on the internet.

 

[Martijn]

To push out lead, you can also use battery acid.

 

[paul_bogdanich]

I always thought one uses copperas when inquarting. It looks like I'll have to read up on this again.

The equation for copper and nitric is

Cu	4HNO3	=	Cu(NO3)2	2NO2	2H2O
63.546	252.048	=	315.594
20.14%	79.86%

The equation for silver (not sterling pure silver) is

3Ag	4HNO3	=	3AgNO3	NO	2H2O
323.604	252.048	=	575.652
56.22%	43.78%

Sooo, dissolving 100 grams of copper consumes about 425 ml of 67% nitric acid while dissolving 100 grams of silver only consumes about 85 grams of 67% nitric. But silver is expensive so you have to make some provision to recover a large percentage of the silver. If you don't recover the silver then it's cheaper to burn the nitric acid as opposed to wasting the silver.

 

[cejohnsonsr1]

Most drain cleaners in the US perhaps, in Europe they are all NaOH.

It really takes very little excess nitric to get a very vigorous reaction with the fine gold. I am a bit lazy and generally will not bother with getting rid of excess nitric. Reducing with SMB can then be problematic since as you say it is an exothermic reaction. With ferrous sulphate the only thing that happens is you have to use more and the solution goes really really dark.

The heat only becomes a problem if you have more than about 3 oz of gold in solution. It’s easy enough to deal with by adding ice made from distilled water to the solution before precipitation. It’s also a good idea to add ice before filtration.

 

[jord]

Sorry to restart the thread, i just wanted to say thanks to all who commented. I used all the tips given and was able to recover 59.65 grams of pure gold from 108 grams 9k & 29 grams 18k

 

[Martijn]

Thank you for sharing a picture of that beautiful shot!
Well done

 

[jord]

Thank you for sharing a picture of that beautiful shot!
Well done

Wouldn't be possible without this forum and hokes! Again many thanks