Waste treatment and cementation

timsiggins

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Hey guys so I’m in the process of treating my waste I put a big copper pipe in and som thin copper sheet and they are gone now, I got a lot of fine white powder. Is this unusual I read in pole book the I want to keep the PH low so I do and then I put my copper let it sit for a few day decanted and it gone. Is this right so I put more copper in and is the white powder
 

butcher

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Assuming the waste was from a chloride solution.

Several salts can be white, some of the more common ones you may be dealing with like lead, silver, and copper.

Very hot water will help to put lead chloride into the wash solution, so you can wash lead out.

leaving copper salts and silver salts, elemental gold, or any other valuable metal.

Copper I chloride (a fairly insoluble white powder), will form soluble Copper II chloride with fresh HCl and air (coloring the solution blue, green, or almost brownish-black depending on dilution and acidity, as well other factors as to what valence or concentration have you.

Silver will not be more soluble in hot water, and very little (almost non will go into solution with the HCl acid and air, although it is fluffy and needs time to settle (while you are washing the lead out with hot water).

Lead salt tends to form needle-like crystals and can look more clear (than white), whereas silver chloride (unexposed or reduced by light to dark crystals)) is more white and light and fluffy than the lead chloride salts.


Once washed of free acid the white silver chloride can turn a violet-black from exposure to the sun.

To save on generating excessive toxic waste, you can reuse the hot water used to dissolve more lead salt, removing the lead chloride by letting it cool precipitating and decanting the solution from the lead crystals, and reheating it for reuse again, using two different portions of water will speed the process as when one is hot the other is cooling...

copper metal will only go into solution as ions if it is oxidized or made to lose electrons where something else in a solution that wants those electrons to be reduced itself, the acid will oxidize or take electrons from the copper is oxidized giving up electrons to the acid, the copper colors the solution with ions, the acid is reduced the chloric acid gains electrons it shares with copper to form a salt of chloride ions in solution.

Copper I chloride can be put back into solution (oxidized) with electrons from HCl changing the valence of the copper ions or salts, here again, the acid is reduced in the chemical reaction.

At this point forget about pH, acids being consumed will affect the pH, as the acid is reduced to salts along with your copper, once the copper consumes all the free acids it will give up electrons to the values in solution (if any like gold) and some copper will be consumed or be converted to ions as the gold ions get an electron (from the copper) the gold is reduced to elemental gold and will form a black impure gold powder once enough gold atoms cluster together to overcome the gravity of the solution and precipitate, some of the black gold powder may stick to your undissolved copper and need to be brushed free from the remaining copper buss bar.

Read the book again to see if say's C.M. Hoke.
Or are you learning from Pole.s or Poke.s book?
 
Last edited:

Martijn

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Very valuable info in butchers post. Read and research it until you understand it.

If you leave the copper too long in the stockpot solution, it will start acting as AP. Consuming copper as long as there is free HCL and copper 2 chloride.
Your waste solution should be free of oxidizers like nitric and bleech after precipitating any gold, and especially after consuming a sheet of copper.
If the cemented black powders stay solid, there is no oxidizer left.

The pm's will cement out in a couple of days or a week. You can take the copper out, brush it off, and maybe test with a clean piece to see if there's something still cementing out.
Let it settle until clear and decant or siphon most of the waste solution to the iron bucket.
Do the same here. Take the iron out after no more precipitate forms after you tap it clean. Wait a day to see. Stronger acidic waste creates a harder copper cement layer, I've noticed. So tap it off often or test with a clean piece of iron.
My stockpot and iron pot are transparent buckets, so i can see the cementing going on from the side. Helps alot.

Martijn.
 

Geo

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If the PH is low and there is excess nitric acid or any other type of oxidizer, it will force the CuCl2 from various processes to attack the copper and dissolve more copper than the solution can absorb. The excess gets pushed out as CuCl, which is a white solid that can be colored by the solution. Take some of the solids and see if it will dissolve completely into fresh HCl.
 

Geo

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It's best to dilute the solution before cementing so that it doesn't just chew up the copper without cementing any precious metals.
 

timsiggins

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Ya my copper has been getting chewed up I think I will have to buy a few more bucks and dilute unless I come home and it not eatting the copper any more I put alot in, I figured that the copper would use up the nitric
 

Martijn

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It's the copper 2 chloride that's eating your copper. All the values will have cemented out. Stop adding more copper.

But to be clear, please answer this: How much acid did you use and which acid? HCL or nitric or both?
 

Geo

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It's the copper 2 chloride that's eating your copper. All the values will have cemented out. Stop adding more copper.

But to be clear, please answer this: How much acid did you use and which acid? HCL or nitric or both?
From timsiggins
"I figured that the copper would use up the nitric".
I'm assuming it is a nitric acid solution. Dilution for PH adjustment is still recommended by me. Not a perfect choice as it generates more waste solution but it is the most efficient, in my opinion.
 

Martijn

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Thanks GEO. Completely missed that somehow. Ignore my replies about chlorides.
Sounds like it's still usable nitric, in stead of waste. I was wondering why he wants to treat nitric as waste.
Keep it aside for dirty AR dissolution or sterling silver or inquarted gold?
 

upcyclist

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Thanks GEO. Completely missed that somehow. Ignore my replies about chlorides.
Sounds like it's still usable nitric, in stead of waste. I was wondering why he wants to treat nitric as waste.
Keep it aside for dirty AR dissolution or sterling silver or inquarted gold?
This. Always use your nitric acid until depleted, unless you are toll refining or feel like burning money and time. If you're toll refining, start with less than you need, and add nitric until the dissolution reaction is complete.

Edit to add: Figure out how much nitric you need by weighing your input material, estimating the alloy if you need to, and I suggest rounding down. You should be very close, so you won't need to add nitric forever. You can search the forums for info on how much nitric is needed for copper or silver (hint: different answers for different elements).
 

Jado

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Thanks GEO. Completely missed that somehow. Ignore my replies about chlorides.
Sounds like it's still usable nitric, in stead of waste. I was wondering why he wants to treat nitric as waste.
Keep it aside for dirty AR dissolution or sterling silver or inquarted gold?
Or distill the nitric off.
 

Noggin

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If your waste bucket has substantial sulfuric acid or sulfate content you may be creating some less soluble sulfates like silver or lead.
This might be something to consider as I think you need electrolysis to recover those.
 

Geo

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We would absolutely like to get the most of what we buy to use. Sometimes we have to accept that there are expenses called "acceptable loses". That's where you have to decide on whether chasing something, that you should have budgeted into the cost before starting, is worth the effort. Experience will give us the knowledge of what not to do. Sometimes, that's worth more than knowing what to do. There may only be one way to do something but hundreds or thousands of ways that it can't be done. Experience is when you tried enough of the ways it can't be done to except that you can only do it the one way or not at all. It's amazing the number of people that never seems to get to that point. Not pointed at anyone in particular, I mean in general. I do it myself. I wonder "what if?" all the time.
 

timsiggins

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What what ph will I bring my waste solution to drop all the iron out, right now I have something that kinda looks like black oatmeal but watery oatmeal
 
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