Dealing with Waste

[DylanDownright84]

Thank you, sir for clearing that up. I had read on the forum about something similar, but havent experienced it until recently. I realized I was chasing a very small amount of PGMs (maybe a gram or two that wouldn't cover the cost of added time and chems to catch them) when i got my solution evaporated down to the last few liters.

I split the last remaining solution, about 4L into two separate vessels. One with copper bus, the other with -325 mesh copper powder, both on heat. The copper bus did cement a very small amount of "blacks" sticking to the copper pieces. the other vessel I stirred the copper powder into while hot and it turned black and took a week to even see anything settle. Both solutions were heated during this. I probably collected less than 2g of fine black powder at the end. So next time, my solutions are just gonna go to my iron bucket.

I'll chock it up as a learning experience with evaporating large amounts of waste. Just seems that when I take even small test batches of either my AR bucket solution or Ag cement bucket solution, evaporate a few hundred ml down to about 50, add some hcl, I get positive stannous tests for PGMs and Au. Or just PGMs. I keep generous amounts of Cu in each with bubblers and I even stir them both once a week usually. And solutions have weeks, sometimes a month or two in the cement bucket.

I've been told to raise ph with sodium hydroxide to ph4, that might help. Use copper powder with the bubblers a few days before you plan on processing the cement bucket waste, which are copper nitrate and have copper in them already. The powder offer more surface area. Maybe that's it. Use bleach, dry bleach-pellets for pool use. Bubbling chlorine gas into solutions, not really wanting to go there.

I now know I'm really just worrying over a couple grams of PMs, but I'd like to solve the issue of incomplete cementation in my AR and Ag cement buckets.

Thanks everyone! Hope everyone had a good 4th!

 

[francisco rodriguez]

Hello everyone, a question, if due to lack of experience I take the pH to 14 instead of 11? Would the correct thing be to go down with water, acid or wait?

Thanks.



Paco.

 

[butcher]

Paco,
Adding acid will create a large chemical reaction, so be careful to have plenty of room for expansion, it can create a lot of heat, be careful not to heat the glassware too much too fast, and do not forget to wear your personal safety equipment...


Slow careful additions of acid will lower the pH, stir well and allow time between small additions and before checking the pH level or making adjustments, the change of pH with acids and bases or alkalies can create heat with the chemical reaction which can affect the pH measurements, stir the solution and let the reaction settle give it time before checking it, you may notice color changes of the solution as the different metals dissolve into solution or precipitate out of solution at the different pH ranges.

 

[FrugalRefiner]

Paco, I don't think there is any advantage to raising the pH to 14. Everything that's going to precipitate should do so by pH 11. Taking it higher just costs more in chemicals, both in raising it that high, and then adding acid to lower it to neutral.

Be sure to decant the liquid off at various stages when you're raising the pH. Some metals (e.g., aluminum, antimony, chromium, lead, tin, and zinc) will precipitate as the pH is increased, but then redissolve as it goes higher.

Once you've raised the pH to 11 and separated the liquid from the precipitates, lower it back to neutral with acid.

Dave

 

[francisco rodriguez]

Thanks for the quick responses, raising it to 14 has been an accident, I did not expect it to change color with so little sodium hydroxide and when I measured it was already at 14. I will go down very slowly with additives drop by drop, after all, I do this to learn, and without any rush.

Thank you very much again.


Paco.

 

[FrugalRefiner]

Ahhh... I understand better now.

So since you ended up at pH 14 by accident, I would separate the liquid from the precipitate, then slowly bring the pH back down with acid additions. Watch for any precipitates that may have redissolved when you went too high too fast, that may precipitate again. To be honest, I don't know whether they will or not. I've never been in this situation. But in case they do, be prepared to separate the liquids from the solids as you go.

Dave

 

[francisco rodriguez]

 

[francisco rodriguez]

All happily resolved, thank you very much again.

Paco.

 

[rewalston]

I'm looking for alternatives to raise the PH of my waste solutions (after the copper and iron treatments). I know that Sodium Hydroxide is generally used but creates a filtering nightmare. I've also heard about using lime, but there is no immediate reaction so can't really use test strips to check PH and I don't know how well it filters. Are there any other chemicals that will work?

 

[Martijn]

Soda ash

 

[rewalston]

Soda ash

how well does it filter?

 

[Martijn]

Filtering hydroxides simply takes some time. It's fluffy, it's slimy and clogs things up.
Big coffee filter in a plastic strainer works fine. You can do other things while filtering or as some do; set up 10 or more buckets with filters to speed things up.
My soda-made metal hydroxides usually take a couple of hours to filter.

 

[goldenchild]

If you want a set it and forget it type of method you can use the towel wick method. I believe I got the idea from good ol' GSP (RIP). For the things that refuse to settle you can take your 5 gallon bucket and insert a towel that is long enough to touch the bottom and long enough to hang over the lip of the bucket. The towel should be rolled up to act as a wick. Tilt the 5 gallon bucket enough so that the towel can hang over another bucket. Through capillary action the liquid will eventually all drip into the receiving bucket. As the liquid level of the bucket with the towel in it lowers you can tilt the bucket more. That shouldn't be needed if your towel touches the bottom. It's slow as hell but at least you don't have to keep waiting and feeding/replacing filters as they fill with material. No clogging to worry about with this method either. It's a one pass solution that yields crystal clear waste solution.

 

[rewalston]

If you want a set it and forget it type of method you can use the towel wick method. I believe I got the idea from good ol' GSP (RIP). For the things that refuse to settle you can take your 5 gallon bucket and insert a towel that is long enough to touch the bottom and long enough to hang over the lip of the bucket. The towel should be rolled up to act as a wick. Tilt the 5 gallon bucket enough so that the towel can hang over another bucket. Through capillary action the liquid will eventually all drip into the receiving bucket. As the liquid level of the bucket with the towel in it lowers you can tilt the bucket more. That shouldn't be needed if your towel touches the bottom. It's slow as hell but at least you don't have to keep waiting and feeding/replacing filters as they fill with material. No clogging to worry about with this method either. It's a one pass solution that yields crystal clear waste solution.

I had completely forgotten about wicking, that would probably be the best option, just have to get me a few more buckets so I don't tie up the filtering ones.

 

[kurtak]

If you want a set it and forget it type of method you can use the towel wick method. I believe I got the idea from good ol' GSP (RIP). For the things that refuse to settle you can take your 5 gallon bucket and insert a towel that is long enough to touch the bottom and long enough to hang over the lip of the bucket. The towel should be rolled up to act as a wick. Tilt the 5 gallon bucket enough so that the towel can hang over another bucket. Through capillary action the liquid will eventually all drip into the receiving bucket. As the liquid level of the bucket with the towel in it lowers you can tilt the bucket more. That shouldn't be needed if your towel touches the bottom. It's slow as hell but at least you don't have to keep waiting and feeding/replacing filters as they fill with material. No clogging to worry about with this method either. It's a one pass solution that yields crystal clear waste solution.

Good advice :!:

Here is a link to wick filtering by GSP

:arrow: GSP,s cloth filter....it really works as I found by accident

Here is a thread with pics of my wick filter set up

:arrow: Wick filter

Kurt

 

[rewalston]

The following is from another thread that I haven't gotten a response to.

I have some waste questions about the process. Once you have soaked the boards hcl (you stated it can be used twice) what part of the waste stream would you place this solution of different metals into? There is going to be tin, possibly lead, potentially some silver and possibly gold which the solder would have dissolved when the boards were originally produced. So I'm not exactly certain where it would go.

Palladium wrote: ↑Fri Sep 16, 2011 7:04 pm
Here’s how I do mine and some things I have discovered.

After you filter the hcl you can use it again for the next batch. I find it works well for 2 batches. .......

 

[g_axelsson]

It sounds like he just uses the acid for more than one batch until the acid is spent.

Gold and silver dissolved in the solder would end up as solid waste sludge and could be collected in a filter. The amount would probably be tiny and not worth bothering with.

I once did a test of lids from pentium MMX (black fiber CPU) lids that were soldered to a gold surface. I could detect gold in the sludge after 50 lids were cleaned in HCl but after aqua regia of the sludge I only got a pale purple stain from my stannous test so I don't care to clean the lids any longer.

If you really want to get clean hydrochloric acid back you could just distill off any remaining acid. The acid that is used up has been transferred into chloride salts and will stay behind as tin and lead chlorides.

Göran

 

[jhop1994]

Waste treatment for the small refiner.

Very much appreciate such a detailed and well expressed post. This was definitely a qualitative change for me in my knowledge of refinement. Thank you.

 

[rewalston]

So, what part of the waste stream would it go into? The bucket with lead to drop everything prior to treating with lye for disposal?

It sounds like he just uses the acid for more than one batch until the acid is spent.

Gold and silver dissolved in the solder would end up as solid waste sludge and could be collected in a filter. The amount would probably be tiny and not worth bothering with.

I once did a test of lids from pentium MMX (black fiber CPU) lids that were soldered to a gold surface. I could detect gold in the sludge after 50 lids were cleaned in HCl but after aqua regia of the sludge I only got a pale purple stain from my stannous test so I don't care to clean the lids any longer.

If you really want to get clean hydrochloric acid back you could just distill off any remaining acid. The acid that is used up has been transferred into chloride salts and will stay behind as tin and lead chlorides.

Göran

 

[goldenchild]

So, what part of the waste stream would it go into? The bucket with lead to drop everything prior to treating with lye for disposal?

It sounds like he just uses the acid for more than one batch until the acid is spent.

Gold and silver dissolved in the solder would end up as solid waste sludge and could be collected in a filter. The amount would probably be tiny and not worth bothering with.

I once did a test of lids from pentium MMX (black fiber CPU) lids that were soldered to a gold surface. I could detect gold in the sludge after 50 lids were cleaned in HCl but after aqua regia of the sludge I only got a pale purple stain from my stannous test so I don't care to clean the lids any longer.

If you really want to get clean hydrochloric acid back you could just distill off any remaining acid. The acid that is used up has been transferred into chloride salts and will stay behind as tin and lead chlorides.

Göran

Not clear on what your question is here. Are you asking what one would do with the bucket of HCL that contains dissolved lead? If so then you would just take care of it on it's own. No need to mix it with anything else from any other process. Drop the metals in the HCL and isolate them from the acid. Treat the acid and dispose of it. You'd then take the lead and separate it from the PMs. Like mentioned it may or may not be worth the trouble of separating the PM's from the lead. Then you simply dispose of the lead. Make bullets. Maybe an anode bar for a deplating cell. Fishing weights possibly? Whatever.