Dealing with Waste

[Yggdrasil]

Maybe the sodium hydroxide has reacted with the CO₂ and carbonized.
Open container or old batch?
NaOH should be stronger than soda ash.

 

[Martijn]

So add iron when it gets to 7? Or the iron already has dropped when it reaches 7? I finally got soda ash and it works so much better then the sodium hydroxide. I've already added the iron for a few hours before I started to raise the pH. So is it my understanding that as I've increased the pH the iron has dropped correct? The liquid looks shiny on the top. But it's otherwise clear. Till you reach the bottom where the metal collected. I want to do this correctly.

You misunderstood somewhere..

Displacement of metals in solution: a more reactive metal in placed in a solution containing lesser reactive dissolved metals(salts). The salts in solution are displaced by the more reactive metal, which goes into solution. Look for reactivity series wikipedia. There is a table with the order of reactivity.

Stockpot: all solutions after gold, PGM's or silver precipitation go in there. It's a bucket with some copper in it to displace the all precious metals (recovery of traces). Copper goes in solution in this step to get pm's out.

Iron pot: the second step after the stockpot. here the same reaction takes place, i.e. displacement of all lesser reactive metals onto IRON. Iron goes into solution in this step to get copper, nickel and more out.
So after the iron pot there is a lot of iron in the solution the needs to be taken out.
All the more reactive metals than iron will also be in solution, as copper and iron can't get them out; due to the reactivity series.

Both the stockpot and the iron pot use an air bubbler for circulation to get all the metals out by displacement. With air added, it also acts as an 'AP' bath (or iron chloride leach for the iron pot), so don't leave the copper in to long, it will be consumed as long as the is free HCL. (which by the way will save you on soda ash for not having to neutralize the free acid.. Pull out the copper upon formation of CuCl1.)

You can tell by the color of the waste water in the iron pot if most of the copper has been displaced. From darker green to pale green.
You can also test for copper with ammonia. (test means a couple of drops of solution in a spotplate and a couple drops of ammonia added to see the effect)

After the iron pot a lot of the harmfull metals are out and we continue to pH precipitation by adding lye or soda ash to the filtered iron pot solution.
In this step salts are pushed out of solution because the salt is not soluble in high pH solution. It falls out as a hydroxide. Not as metal. Hydroxides can have completely different colors than their metals, and can look metallic but also like slime.

You don't add iron to your pH precipitation.

Filter when it gets to (7) 9 and once more @pH11. @ 7 is optional.

Martijn

 

[Martijn]

I just read 4metals actually raises the pH to 2.5 before adding iron to the iron pot. That is something different.
adding iron at pH 7 would not have any affect I think, because iron is not soluble at that pH, so I expect displacement not to occur in that situation.

 

[Rreyes097]

I Rose the pH to 2.5 and put iron in it that's when I put the iron I've already done the copper before that. So I guess I gotta filter@7 like I am right now. Then I'll raise it again to 11 and filter again. I got that right? Also is this the same procedure for day nitric and sulphuric acid? I have some waste of that from using it for silver plating. But I don't think I'll be doing that again.

 

[Martijn]

Have you read the entire post on page one from 4 metals? Most of the answers to your questions can be found there. Other questions may require reading more pages.
Not trying to be unwilling, but doing some research and putting in the effort by yourself will make the do's and don'ts stick better than us telling you how to. Your question is answered in the first sentence.
You also should filter/decant after the iron pot, before raising pH.

 

[Rreyes097]

Yes I've read it. But I'm just trying to confirm my understanding. Hence my questions. And I've read everything regarding waste. Well everything I can find of course.

 

[Martijn]

He wrote:

"The procedure that follows is for your acid waste only, it is not for cyanide or leaching type wastes, only the spent acids used to digest the metals you have refined."

:wink:

 

[Rreyes097]

Martin, so that post you posted means it is ok to do this with my nitric and sulphuric acid waste? Because that sentence you quoted says it's for my acid waste only. But does it matter what kinds of acids? It doesn't say. But thanks.

 

[Martijn]

Yes, all the acid waste including sulphuric.
H2SO4 will take a lot more soda ash to neutralize, as I've noticed, and you may have to dilute it or use lime to neutralize it before the pH will start to rise.

I think in my case the solution was saturated with soda ash and could not dissolve anymore soda ash, stopping the neutralizing reaction.
You could look for other uses for the sulphuric waste to deplete it before treating it as waste.
I'm sure butcher has some some suggestions. How much sulphuric waste do you have? And from which process?

 

[Rreyes097]

I have about a gallon or half gallon I can't be sure of sulfuric acid and nitric acid that I used to get silver plating off of silver plated stuff. My other sulfuric acid waste is from my sulfuric acid cell for gold plating which is diluted with distilled water.

 

[Topher_osAUrus]

Make copperas. Boom. Recycled

 

[Dbaschiera]

What I did with my first 7 grams of recovered gold, is a rolling ring hand hammered from a small button.
.
No fancy stones or anything, this was hard enough for me, but lots of fun to do and even more to give to my wife.
Lost wax casting method will be my next try.

Hi Martin, lost wax method is the way to go. I have been melting metal for sometime…I use copper and brass scrape to make crosses and other items…I use two methods 1. Petra bond sand with molds I’ve made and loss wax method. I have a 3D print so I design my items that way for the molds. Good luck and I’m sure the wife loves it!
Dino

 

[Dbaschiera]

Hi Martin, lost wax method is the way to go. I have been melting metal for sometime…I use copper and brass scrape to make crosses and other items…I use two methods 1. Petra bond sand with molds I’ve made and loss wax method. I have a 3D print so I design my items that way for the molds. Good luck and I’m sure the wife loves it!
Dino

Very nice video!!

 

[Rreyes097]

I've been trying to raise the pH on this gallon on waste which includes nitric and distilled water. Basically the waste from silver processing. I thought the soda ash was better than sodium hydroxide but it seems to me that it takes a lot longer and a lot more soda ash then what it would have taken for sodium hydroxide but the sodium hydroxide raises the temperature of the waist and I'd rather not do that. But the soda ash bubbles up and wants to over flow the container I have it in. Not sure how to speed this process up or even do it more efficiently. But I'm trying to be environmentally friendly as a refiner should be it's just frustrating and so time-consuming.

 

[Yggdrasil]

That's chemistry my friend.
You may not like it, you may not even want it, but it is what happens.
A plan is worth more than a thousands regrets, but that requires that you understands what happens and what you expect to happen. (Hokes anyone?)

 

[Martijn]

I used to have that happen to me in the beginning when i used too much acid. Or when treating with sulfuric acid waste.
The soda ash reacts violenly with free acid. Creating gases. Once most of the the acid is destroyed, the pH will start to rise.
Take your time and keep adding slowly.
Soda ash is cheaper than NaOH, that's why i use it.
As you get more experience in how much acid is needed, the waste treatment will go faster.

Martijn.

 

[Martijn]

Another basic rule in chemistry and waste treatment is never fill a reaction vessel more than half. Leave room for the reaction and use a catch basin for overflowing.

 

[Elemental]

Secondary containment should be considered at all times during all parts of the chemical reaction process. It can be as simple as a large Rubbermaid tote that holds a 5-gallon bucket or two that can hold waste material if it should a bucket fail, or having a ceramic dish beneath your beakers on a hot-plate. Too many times, I've been reading about people asking how to recover metal from dirt, concrete, sand, etc. Even when doing melts in my electric furnace, I have secondary containment in case my graphite crucible were to break. It's a hell of a lot easier to separate a glob of silver from a metal pan than to watch it go in the dirt or concrete.

Elemental

 

[Rreyes097]

Thanks Martin

 

[MicheleM]

Hello everybody,
I have a question for you
I'm dealing acid waste these days. I have 2 different buckets; in one bucket I put an iron bar and I'm waiting for complete cementation of copper and other base metals before filtering and raising the pH , in the second one i used Aluminium for cementation and after filtering I'm raising the pH with baking soda. at pH 4 the solution appears orange with some gelatinous substance (Al hydroxide I guess), it is normal? Why the orange colour?
Thank you , have a good day