My Plan - New to Refining. I would love a review please.

[Ellias]

Hello all, i have not done any refining yet and only tested at maximum 50 - 100 ml hcl and nitric separately (also was successful in making nitric with hcl and sodium nitrate (again very low levels)

How i assumed to make nitric with NaNO3. Since chemical balance equation was 1 to 1 HCl and NaNO3 i assume the following with my 20% HCl. 100 ml of HCl should be containing 20g HCL and i added 20g NaNO3 to the 100 ml solution to make 20% Nitric (ive had seem small bits of silver cement with copper displacement and definitely got my copper to dissolve immediately). This was with around 100 g of cleaned boards. Am I correct? Funny story here - when I was first testing i accidentally added HCl midway and got a white cloudy solution. I mightve lost some silver (was just playing around with various metals at 50 ml a ways back.

safety gear:
- respirator
- airtight goggles
- alkaline and acidic resistant gloves reaching to elbows
- sodium bicarbonate bath for accidents

Gear:
- (2x 1000ml beaker (thick head resistant)
- (vacuum flask)
- hot plate
- pp5 or hdpe plastic containers
- Stannous Chloride

1. I plan to strip everything off board and dip in lye bath (small amount 10-20%) to clean the solder mask.

2. Clean rest of misc with only hcl bath. Id keep this solution for reuse in the future. (My goal is remove unwanted iron,lead,tin etc etc)

3. Nitric acid bath (dilute 10-20%) and save for silver/copper recovery & reuse.

4. (Never made AR - so still reading into levels and math but i have 20%hcl, 31% hcl, 69% nitric, distilled H2O, and sodium nitrate as my gear) will test small batches until i made a good AR solution

5. AR with hopfully the gold (still planning)

How i safely/ethically dispose of acids (plan):

1. Steel or iron to precipitate everything
2. Collect the (hopefully) copper silver
3.NAOH solution to neutralize to ph7
4. Fine tune with baking soda
5. Vaccum to throw iron rust away
6. Pour rest down sink

How would one neutralize AR solution? Just the same as NaOH/ baking soda?

Does this plan sound reasonable? Am I disposing well? Is there a better way? (I am willing to only do small batches - 500ml max)

 

[Ellias]

I just want to say im aiming for pcb boards only right now (no plans on pins or anything else)

 

[eaglekeeper]

safety gear:
- respirator
- airtight goggles
- alkaline and acidic resistant gloves reaching to elbows
- sodium bicarbonate bath for accidents

A respirator is good for a backup, but I don't think there are any (affordable) filters that will withstand acidic fumes for very long. You would be better served to use a fume hood.... A DIY hood can be made fairly cheap. I would also recommend your vacuum flask be heavy walled.

1. Steel or iron to precipitate everything
2. Collect the (hopefully) copper silver
3.NAOH solution to neutralize to ph7
4. Fine tune with baking soda
5. Vaccum to throw iron rust away
6. Pour rest down sink

Check with your county office and see if they have any programs to turn in residential chemical wastes. Where I live, they call it Amnesty Day and they accept just about any residential chemical wastes....free.

 

[Ellias]

A respirator is good for a backup, but I don't think there are any (affordable) filters that will withstand acidic fumes for very long. You would be better served to use a fume hood.... A DIY hood can be made fairly cheap. I would also recommend your vacuum flask be heavy walled.



Check with your county office and see if they have any programs to turn in residential chemical wastes. Where I live, they call it Amnesty Day and they accept just about any residential chemical wastes....free.

Thank you so much! Ill look into the county and i saw i am able to throw rust as long as it is in small amounts and im 100% sure i ended up with salt water with co2 gas in the test runs. BUT ill look into chem waste programs!

Update: my county does it free during working operations. THANK YOU Eagle!!

Regarding the vacuum flask - it is extremely thick! But i made a DIY 3V vaccum pump so nothing crazy with high pressure. Also i have been using chem lab grade for safety!

 

[Ellias]

A respirator is good for a backup, but I don't think there are any (affordable) filters that will withstand acidic fumes for very long. You would be better served to use a fume hood.... A DIY hood can be made fairly cheap. I would also recommend your vacuum flask be heavy walled.



Check with your county office and see if they have any programs to turn in residential chemical wastes. Where I live, they call it Amnesty Day and they accept just about any residential chemical wastes....free.

Other than these points - how does the overall plan look?

 

[Yggdrasil]

Other than these points - how does the overall plan look?

Read these links first:
We ask our new members to do 3 things.
1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: Screen Readable Copy of Hoke's Book
2. Then read the safety section of the forum: Safety
3. And then read about "Dealing with waste" in the forum: Dealing with Waste

Suggested reading: The Library

https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/

 

[Yggdrasil]

Other than these points - how does the overall plan look?

The major challenge with your plan is that is set in stone.
Most processes do not adhere to your plans, they do what they are supposed to do according to a much wider set of variables than we can plan for.
So you need to start slow until you are familiar with the reactions and can adjust the variable in our control to get the result we want.

Start with the acquaintance test in Hokes book.

 

[Ellias]

The major challenge with your plan is that is set in stone.
Most processes do not adhere to your plans, they do what they are supposed to do according to a much wider set of variables than we can plan for.
So you need to start slow until you are familiar with the reactions and can adjust the variable in our control to get the result we want.

Start with the acquaintance test in Hokes book.

Thank you so much! Ive read a lot of what you sent (i was following the neutralization perfectly to the T. I do have ph strips so i can check that off. Now with the county thing i should have ample ethical discarding techniques and processes).

Safety wise, i got everything besides the hood. Ill work on that one too.

Still reading up on Hokes book

 

[eaglekeeper]

Safety wise, i got everything besides the hood. Ill work on that one too.

If you use the search bar at the top, there is plenty of designs on the forum for a DYI fume hood.

 

[4metals]

This link can help you with a few of the things that have been suggested.

https://goldrefiningforum.com/threads/moderator-curated-thread-searches.34576/

 

[Master Nater]

latest posting on home-made fume hoods:

https://goldrefiningforum.com/threa...t-hoods-and-fume-scrubbers.34601/#post-373037

 

[Martijn]

Hello all, i have not done any refining yet and only tested at maximum 50 - 100 ml hcl and nitric separately (also was successful in making nitric with hcl and sodium nitrate (again very low levels)

How i assumed to make nitric with NaNO3. Since chemical balance equation was 1 to 1 HCl and NaNO3 i assume the following with my 20% HCl. 100 ml of HCl should be containing 20g HCL and i added 20g NaNO3 to the 100 ml solution to make 20% Nitric (ive had seem small bits of silver cement with copper displacement and definitely got my copper to dissolve immediately). This was with around 100 g of cleaned boards. Am I correct? Funny story here - when I was first testing i accidentally added HCl midway and got a white cloudy solution. I mightve lost some silver (was just playing around with various metals at 50 ml a ways back.

safety gear:
- respirator
- airtight goggles
- alkaline and acidic resistant gloves reaching to elbows
- sodium bicarbonate bath for accidents

Gear:
- (2x 1000ml beaker (thick head resistant)
- (vacuum flask)
- hot plate
- pp5 or hdpe plastic containers
- Stannous Chloride

1. I plan to strip everything off board and dip in lye bath (small amount 10-20%) to clean the solder mask.

2. Clean rest of misc with only hcl bath. Id keep this solution for reuse in the future. (My goal is remove unwanted iron,lead,tin etc etc)

3. Nitric acid bath (dilute 10-20%) and save for silver/copper recovery & reuse.

4. (Never made AR - so still reading into levels and math but i have 20%hcl, 31% hcl, 69% nitric, distilled H2O, and sodium nitrate as my gear) will test small batches until i made a good AR solution

5. AR with hopfully the gold (still planning)

How i safely/ethically dispose of acids (plan):

1. Steel or iron to precipitate everything
2. Collect the (hopefully) copper silver
3.NAOH solution to neutralize to ph7
4. Fine tune with baking soda
5. Vaccum to throw iron rust away
6. Pour rest down sink

How would one neutralize AR solution? Just the same as NaOH/ baking soda?

Does this plan sound reasonable? Am I disposing well? Is there a better way? (I am willing to only do small batches - 500ml max)

I would not use Nitric on PCB's, but AP.

When making AR, cover the pieces in HCL, heat it to 80C and add drops of nitric at a time. keep the beaker loosely covered to recycle the NO2 gas back in HNO3.
Only add more once all reaction has stopped.

When you're more experienced, you can add more at a time, but never too much, then you don't have to:

How would one neutralize AR solution? Just the same as NaOH/ baking soda?

But simply cement or precipitate your pm's from solution.
You don't neutralize the solution, you de-NOx it. Neutralizing means raising the pH and thus making hydroxides. Precipitation works in acidic environments.

As Yggdrasil said, start with small tests with test tubes, until you are more familiar with the reactions before you scale up.

Never fill a beaker for a digestion or other reaction more than one third, to avoid boil overs.
Use catch basins in case of spills and breaks. etc. etc.
Start small, small messes to clean up.
Throw test solutions in the stockpot, don't try to recover micrograms of gold, you will not be able to see the result.
Your stannous will tell you all you need to know. Make a weak reference testing solution of gold chloride. This will tell if your stannous still works.
Perform stannous testing on a filter paper with one drop, never in a solution.
etc, etc.

 

[Martijn]

How i safely/ethically dispose of acids (plan):

1. Steel or iron to precipitate everything
2. Collect the (hopefully) copper silver
3.NAOH solution to neutralize to ph7
4. Fine tune with baking soda
5. Vaccum to throw iron rust away
6. Pour rest down sink

How would one neutralize AR solution? Just the same as NaOH/ baking soda?

Does this plan sound reasonable? Am I disposing well? Is there a better way? (I am willing to only do small batches - 500ml max)

Read and follow the dealing with waste thread, it explains it all. Your plan is a bit off from what we usually do. you precios metals should be out before yo go to cementing and waste treatment.

 

[Brett Novak]

Unless you live somewhere you CAN'T buy Nitric, don't bother trying to make it.

But - for PCB's - the 1st step should be a long (like 1 month long) soak in equal parts Distilled H20 + HCL + Hydrogen Peroxide until you get a reaction. Keep it covered and in direct sunlight if possible to keep it warm. As the mixture evaporates off (leave it OUTSIDE!!! add more of each to keep the reaction going.) This will flake the gold sputtering off of the boards without dissolving too much junk material. (PCB's have mostly copper in them, which makes AR tricky IMHO.) Especially if they are populated boards, going straight to AR introduces all sorts of other stuff from the other components on the board - specifically a lot of nickel, lead and copper.

Once everything has flaked off, you can wash the boards down with water and take them to a recycler or rubbish.

Now you have a bunch of flake in the bucket - wash this well with water, and filter. Pick out as many of the big components that may have flaked off the board along with the gold, but don't drive yourself crazy.

Filter it a few times, then into a glass beaker and add AR to start the normal process. Starting with raw PCB's means using a lot of nitric ($$$) and even more waste solution - where the HCL + HyPerox can be easily neutralized with Urea

Don't expect much - PCB's - even good ones - yield <1% by weight

 

[Shark]

But - for PCB's - the 1st step should be a long (like 1 month long) soak in equal parts Distilled H20 + HCL + Hydrogen Peroxide until you get a reaction.

To much peroxide and you put gold into solution. For PCB’s you don’t even need peroxide to process boards in a month. HCl will do it alone, with a bit of time. HCl two parts to one part water will do the job. If peroxide is needed at all per gallon of HCl only use one to two cap’s full. You only need to convert the copper to AP, or what is actually copper(ll)chloride. If the forum is well researched on this CuCl2, there are ways to speed up this solution. While not as fast as some, it can often be a more through approach when done right.

 

[Brett Novak]

Yep - I agree Shark - I just give it a kick with some peroxide - but I'm doing 20 to 30#'s of boards at a time. Maybe a couple of squirts per gallon or 2 of HCL...

 

[4metals]

When I read a thread like this all I see is confusion. First off, I can be little to no help because I only processed large quantities of boards. But we have a lot of members who will only ever see boards in smaller quantities and need different methods than I can offer. Every time a new member shows up we get another thread like this and I think it's about time that we come up with a definitive thread for circuit boards processed in smaller quantities. Then we can answer future questions with a link.

So how about it hobby small lot experienced processors, why doesn't someone start off with their process, from when you remove any protective mask all the way through dropping the gold. Then others can chime in with options and in the end we can summarize this and end up with a go to thread.

 

[Shark]

Can we get a definition of small and hobby? I have used AP in almost everything from a 1L beaker to 50 gallon drums. I will say this could be a great idea with enough input.

 

[FrugalRefiner]

Shark, that gives you the perfect perspective for this project! You can guide readers on the differences as you scale up. I will look forward to reading what you share!

Dave

 

[Shark]

Shark, that gives you the perfect perspective for this project! You can guide readers on the differences as you scale up. I will look forward to reading what you share!

Dave

It isn’t something I want to type up on a cell phone, . I will try to get on the computer and try it in the next few days. And I don’t do technical very well.