Cementing gold?

[Anslow]

So, after using silver to inquart my gold and then dissolving with nitric I recover the silver by precipitating with copper.
Given that silver is just below gold on the reactivity series could one use a pure silver rod to precipitate gold instead of using SMB? I assume that the dissolution process is different between gold in AR vs silver nitrate it wouldn’t actually cement out. Any input into this? Here’s a pic of my last gold bar which I’m pretty proud of for being my second bar ever made, in addition to my first ever silver bar. The silver bar isn’t very well done, 98%. It will need to be electrolytically refined. Plus some of my placer gold from Washington State. Thanks for the input yall.

 

[HarryLee1506]

I have seen Indonesian friends use a solution called reborn with the ingredient AgNO3 to precipitate gold in an alkaline environment (Cyanide, Jinchan). When you use a silver bar, the gold quickly cements onto the surface of the bar and prevents the cementing process from continuing...

 

[cejohnsonsr1]

Well this app just went crazy and now my original response is gone. Long story short. I don’t think cementation of gold is a very good idea. Especially not with silver. You just went to a lot of trouble to remove everything except gold from your solution. Don’t put metal back in which will have to be removed again. Just use SMB.

 

[Anslow]

Ah noted.

Well this app just went crazy and now my original response is gone. Long story short. I don’t think cementation of gold is a very good idea. Especially not with silver. You just went to a lot of trouble to remove everything except gold from your solution. Don’t put metal back in which will have to be removed again. Just use SMB.

this is a very good point, thank you. I’ll carry on as usual lol.

 

[kurtak]

Given that silver is just below gold on the reactivity series

Actually silver is just above gold (not below gold) on the reactivity series

The reactivity series starts with the least reactive metals at the bottom of the reactivity series & then moves up to the more reactive

silver is more reactive then gold so is above gold

could one use a pure silver rod to precipitate gold

No - & the reason for that is that the HCl in the AR will cause the surface of the silver to turn into a surface crust of silver chloride which will then prevent the ion exchange from taking place required to cement out the gold

in other words - because the HCl in the AR turns silver into AgCl the Ag doesn't go into solution to make the actual ion exchange to cement out the gold

Kurt

 

[kurtak]

I don’t think cementation of gold is a very good idea.

I disagree & I disagree because there are situations where cementing of gold with copper works very well (& in fact IMO is the best option)

Examples of when/where cementing gold with copper works very well (even a better option)

1) VERY dirty solutions (solutions with A LOT of base metals in solution) in such situation SMB &/or other chemical precipitants can & will drag down some of those base metals leaving you with dirty/contaminated gold that needs to be re-refined anyway

Based on my personal experience (& if/when done right) you can get your gold to come down as clean if not cleaner by cementing with copper then by precipitating with chemical precipitants

2) solutions with a lot of free nitric in them - these are situations where you need to use a lot of excess nitric to insure all the gold goes into solution - such as leaching ceramic CPUs &/or ceramic IC chips or leaching bond wires from IC chip ash/concentrates - or using reverse AR to remove gold plating on SS (Stainless Steel)

In those situations - cementing gold with copper can give you back your gold faster & as clean (if not cleaner) if/when done right - then with chem precipitation

In other words - yes - when you have a very clean gold solution to start with & also has very little to no free nitric in it then chem precipitation is the way to go - BUT - if the solution is VERY contaminated (with base metals) &/or has A LOT of free nitric in it - then cementing with copper can be & in fact often is the better way to go

For what it is worth - in my 10 years of refining (for a living) I probably cemented as much gold (if not more gold) with copper then I precipitated with chem precipitation (we are talking MANY ozt. of gold)

AND - the VAST majority of that gold came back at 99.7 to 99.8 with I believe the worst I got back being 99.3 to 99.5

On the other hand I have had gold using SMB come back as low as 98.3 - 98.5

So (based on my personal experience) it is not a question of to cement with copper - or not to cement with copper - but - instead WHEN to cement with copper

Kurt

 

[4metals]

So (based on my personal experience) it is not a question of to cement with copper - or not to cement with copper - but - instead WHEN to cement with copper

Agreed but you should detail what type of copper. I remember a thread you started years back about fuzz buttons and cementing. So type, or particle size, of copper matters!

 

[kurtak]

Here’s a pic of my last gold bar which I’m pretty proud of for being my second bar ever made

Plus some of my placer gold from Washington State.

By the way - NICE pics of your gold stash

Kurt

 

[kurtak]

Agreed but you should detail what type of copper.

So you want me to right a book

Just kidding - the fact is that over the years I have kinda/sorta done that - it is just that "the book" is spread out over MANY replies & articles I have posted in MANY different threads on this forum about the benefits of cementing with copper

So rather then re-writing things I have already posted I will try to find some of the "more detailed" things I have posted about cementing with copper & link them here

This may take a couple days (to find "detailed" articles)

One more thing should be noted here - the use of copper - in refining - is NOT something I came up with &/or figured out on my own - It has in fact something that I "learned" from paying attention to & listening to some of the "old pros" that were my teachers on this forum when I first joined this forum

That is especially true of you 4metals

I remember a thread you started years back about fuzz buttons and cementing.

You are talking about this thread ------

https://goldrefiningforum.com/threads/fuzz-button-interconnects-need-some-advice.22203/#p232030
Had it not been for "your help" in this thread - I would have never had a real & full understanding of the benefits of using copper - in refining - in certain situations

So the truth is that all I am really doing (&/or have done) is to "try" to pass on the knowledge "handed down" to me by "old pros" that were & are much smarter then me

Kurt

 

[Yggdrasil]

So you want me to right a book

Just kidding - the fact is that over the years I have kinda/sorta done that - it is just that "the book" is spread out over MANY replies & articles I have posted in MANY different threads on this forum about the benefits of cementing with copper

So rather then re-writing things I have already posted I will try to find some of the "more detailed" things I have posted about cementing with copper & link them here

This may take a couple days (to find "detailed" articles)

One more thing should be noted here - the use of copper - in refining - is NOT something I came up with &/or figured out on my own - It has in fact something that I "learned" from paying attention to & listening to some of the "old pros" that were my teachers on this forum when I first joined this forum

That is especially true of you 4metals



You are talking about this thread ------

https://goldrefiningforum.com/threads/fuzz-button-interconnects-need-some-advice.22203/#p232030
Had it not been for "your help" in this thread - I would have never had a real & full understanding of the benefits of using copper - in refining - in certain situations

So the truth is that all I am really doing (&/or have done) is to "try" to pass on the knowledge "handed down" to me by "old pros" that were & are much smarter then me

Kurt

We have been blessed with a few of them, sadly they are not all here anymore.

 

[4metals]

Had it not been for "your help" in this thread - I would have never had a real & full understanding of the benefits of using copper - in refining - in certain situations

Being successful in refining requires a wide range of knowledge to succeed. The chemistry end of it has been my specialty but it is not the only knowledge one needs. I am constantly amazed by the specificity of the knowledge members have about certain circuitry. Personally I wouldn't recognize a fuzz button if you bounced it off my head! That is a part of what makes this forum unique, the varied knowledge that is freely shared.

 

[orvi]

Being successful in refining requires a wide range of knowledge to succeed. The chemistry end of it has been my specialty but it is not the only knowledge one needs. I am constantly amazed by the specificity of the knowledge members have about certain circuitry. Personally I wouldn't recognize a fuzz button if you bounced it off my head! That is a part of what makes this forum unique, the varied knowledge that is freely shared.

Yeah. That is very true. I consider myself relatively advanced on the "chemistry side" and theoretical knowledge. Linking possibilities of what happened, how to determine what is what, based on knowledge about basic redox and advanced coordination chemistry... But when I started, I struggled to apply it into some larger scale reactions. And I needed to adapt, build relatively complicated setups for various operations with limited budget, adapt for unusual material feeds and so on. That is the thing which gave me the most experience and ultimately knowledge - things on paper usually look nice, but there is very thin line between success and complete failure in scale-up real world setup.

That is what I like about refining beyond hobby level. If you want to succeed and trhive, you need to be very versatile in terms of knowledge and problem solving based on that knowledge. You need to come up with good ideas how to implement small scale test reactions into 250L plastic drums, solve difficult problems, like how I de-NOx 200L of solution in plastic vessel which I simply cannot place on the stove... How to efficiently filter 200L of solution and skip that part of buying dedicated filtering setup for thousands of bucks etc...

Successful refiner as single person must be good chemist, good pyrometalurgist, have very good "technical" logical thinking, need to know how to use tools and sometimes build DIY extensions of apparatus he currently need (and do it fast, reliable and cheap), good businessman... Lots of things forged into one person are actually needed.

 

[cejohnsonsr1]

I disagree & I disagree because there are situations where cementing of gold with copper works very well (& in fact IMO is the best option)

Examples of when/where cementing gold with copper works very well (even a better option)

1) VERY dirty solutions (solutions with A LOT of base metals in solution) in such situation SMB &/or other chemical precipitants can & will drag down some of those base metals leaving you with dirty/contaminated gold that needs to be re-refined anyway

Based on my personal experience (& if/when done right) you can get your gold to come down as clean if not cleaner by cementing with copper then by precipitating with chemical precipitants

2) solutions with a lot of free nitric in them - these are situations where you need to use a lot of excess nitric to insure all the gold goes into solution - such as leaching ceramic CPUs &/or ceramic IC chips or leaching bond wires from IC chip ash/concentrates - or using reverse AR to remove gold plating on SS (Stainless Steel)

In those situations - cementing gold with copper can give you back your gold faster & as clean (if not cleaner) if/when done right - then with chem precipitation

In other words - yes - when you have a very clean gold solution to start with & also has very little to no free nitric in it then chem precipitation is the way to go - BUT - if the solution is VERY contaminated (with base metals) &/or has A LOT of free nitric in it - then cementing with copper can be & in fact often is the better way to go

For what it is worth - in my 10 years of refining (for a living) I probably cemented as much gold (if not more gold) with copper then I precipitated with chem precipitation (we are talking MANY ozt. of gold)

AND - the VAST majority of that gold came back at 99.7 to 99.8 with I believe the worst I got back being 99.3 to 99.5

On the other hand I have had gold using SMB come back as low as 98.3 - 98.5

So (based on my personal experience) it is not a question of to cement with copper - or not to cement with copper - but - instead WHEN to cement with copper

Kurt

The first step of recovery is to remove as much of the silver and base metals as possible. By the time you get to the point where you’re ready to put gold in solution there shouldn’t be enough that’s not gold to be of much concern. If the solution is that dirty, you didn’t do the 1st part of the job right. Same thing for free nitric. There shouldn’t be much, if any, left at the point where you’re ready to precipitate. And if there is that much free nitric remaining, it will dissolve a lot of copper before it begins to cement, meaning that you’re just contaminating your cloral auric acid with the same base metal you just spent a lot of time and money to remove.

 

[kurtak]

The first step of recovery is to remove as much of the silver and base metals as possible. By the time you get to the point where you’re ready to put gold in solution there shouldn’t be enough that’s not gold to be of much concern.

That is all fine & dandy if you are recovering something like gold foils from plated fingers &/or pins where you can first remove the copper &/or brass with nitric &/or the CuCl2 (AP) process & then dissolve the relatively clean gold foils - BUT - that is not always the case --- &/or if you are a "hobby refiner" wherein the amount of time spent removing base metals before going for the gold is not all that important

However - when you start working on a level of doing "larger" batches of other types of material & doing it as a means of making a living wherein time is important (need to get the job done in a timely manner so as to be profitable) you "often" just do not have the luxury of spending "days" &/or even "weeks" to remove base metals --- doing so will eat up your profits & you will go broke

When refining for a living - you "often" need to go "down & dirty" so that you see your gold back in a day or 2 at the most (one day to put everything including base metal into solution - the next day to recover your gold from solution - wash the gold sponge - dry the gold sponge - & melt gold into bars) so you can move on to the next batch

In fact - when doing this for a living - you have to have multiple batches happening at the same time - & because time is money - down & dirty is your only real option

Just one example; - when you have a batch of 2 - 3 or 4 kilos of ceramic IC chips you can not spend a bunch of time with a torch &/or a hammer to remove the Kovar lids from the chips - then even more time to dissolve the Kovar away to recover gold foils - which then still need to be processed with AR - as well as also running the chips in AR (with Kovar removed) to dissolve gold bond wires & gold plating between the silicon die & ceramic chip in a process separate from the Kovar lids

Processing a batch of ceramic IC chips in that manner will at the very least cost you 2 if not 3 times the time to see you gold back - & again when you are doing this for a living - time is money


You are FAR better served to process those ceramic ICs by going direct to AR to dissolve all the Kovar along with the gold in one shot & when doing that - in order to insure all gold along with all base metals goes into solution you MUST use an "excess" of nitric

Because of the VERY DIRTY solution AND the "excess" of nitric in the solution - I can assure you that the fastest & best way to get you gold back is to cement it out of solution with copper

The same holds true for leaching the gold bond wires from the concentrates of doing 50 - 70 pound batches of epoxy IC chips - you MUST use an excess of nitric & your solution is going to be VERY dirty so cementing with copper is by far your best option to get your gold back

The same is true when dealing with HEAVY plated pins (so heavy plated they pay 5 grams gold per pound) when plating is that heavy even nitric acid has a hard time getting under the plating to dissolve away the copper/brass (takes about 2 day days of boiling the pins in nitric) CuCl2 will likely not even work with that kind of heavy plating --- so again you are far better served to dissolve everything in AR - with an "excess" of nitric - then cement your gold out with copper

Another example is when using "reverse" AR in order to dissolve gold plating off of SS (Stainless Steel) reverse AR dissolves the gold plating & "leaves the SS untouched - BUT - it also "requires a HUGE amount of "excess" nitric - so again you are far better served to use copper to use up that HUGE amount of excess nitric rather then trying to de-nox with what would amount to needing a HUGE amount of sulfamic

So - though there is nothing wrong with your advice - on a hobby level - it becomes a far different story when working with large batches when refining for a living wherein cementing with copper is often "your best friend"

There are "in fact" advantages to cementing with copper - & therefore IMO something every refiner should learn - even on the hobby level

Kurt

 

[cejohnsonsr1]

We’re just going to have to agree to disagree.