Thanks, interesting reading. Possibility of treatment with bases is somewhat less implemented into general refining I guess. So any information is appreciated
Waste Treatment, copper cementation.
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In this context, instead of iron, could I use the ferrite rings found in ewaste? I've got about 5 kg of the stuff and would rather put it to use than just dumping it at the scrap yards.
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Most ferrites are not electrically conductive (to eliminate eddy currents), and contain iron oxides instead of iron metal, so I don't think they'd work as a direct scrap iron replacement. But they often do contain other metals, either nickel (which is too noble to cement copper) or manganese and zinc (which will cement almost everything).
I'd try a test tube sized sample just to see what happens. Please let us know!
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I tried to do a copper cementation out of some second wash AP solution and this is what happened overnite. I put in a piece of steel and the next day I found one brown layer and a reddish layer above it. What would they be? I assume one layer should be copper one would be iron?
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Martijn
Well-known member
Could be copper with other base metals between iron and copper in the reactivity series.
Hello everyone, I tried to do a cementation of the AP second wash solution and I got a bunch of reddish powder on the top and brownish at the bottom. If you can tell me what are these. I do this so that I can get some experience and learn about the process not to recover the material. From what I understand the steel dissolves and goes into solution and the copper cements out (precipitates). The liquid was turquoise light colour from the beginning.
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Just saw this thread. The method originally posted for waste was primarily for waste from aqua regia refining. What happens is the copper is replaced in solution by the iron going into solution as a chloride so the copper comes out as a metal and the iron goes in as a soluble salt.
I prefer to treat the copper nitrate waste by adding sulfuric acid followed by distillation to generate copper sulfate which can be plated out of the solution on to a copper cathode and make very pure copper. One bonus of this admittedly tedious process is you do regenerate nitric acid so you cut down on nitric usage. And you do get back metallic copper to use for cementing Silver from contaminated electrolyte.
And if you had Cu + Ni + Zn + Pb and maybe even Cd in that nitrate soup?
They will be removed in the slimes from the copper cell, or better yet in the pre anode pouring smelt of the copper.
No, I'm saying if you had more than just copper in your waste nitrate liquid. You add sulfuric and drive off the nitrates, so then you get a mixture of Copper Sulfate, Nickel Sulfate, Zinc Sulfate, etc. You can plate out the Copper pretty easy, but the others like to stay in solution....or, as I think you or Chris had referred to them in the past, they end up as floating turds.
Nitrate liquids do not treat by neutralization nearly as nicely as chloride wastes. The hydroxides are slimy and icky whereas chloride wastes are relatively easily filtered.
If you do a smelt type of anode casting process, where you flux to oxidize those metals and do an air or O2 sparge you can minimize those metals before they make it to the anodes to begin with.
Anything remaining in small quantities in your cast anodes will not mess up the anode corrosion and will stay in the slimes.
Anything remaining in small quantities in your cast anodes will not mess up the anode corrosion and will stay in the slimes.
To make the copper cement faster, you can make a simple 'battery' by attaching the iron rod to a copper wire at the top, then bend the other end of copper wire into the beaker/bucket the iron is in. This will create a weak current and rapidly reduce the copper in the solution. Some will even crystalize onto the copper wire, as it acts as a cathode in the cell.
The iron oxidizes, releasing electrons which pass through the wire to the copper cathode, creating another place for copper cations to reduce.
For a big volume, I attach the wire to a copper rod.
The copper in solution is usually all removed down to a trace amount within 4 days, unless there's so much copper ion that it totally dissolves the iron anode before finishing. Then a new iron rod is needed to complete the copper reduction.
The iron oxidizes, releasing electrons which pass through the wire to the copper cathode, creating another place for copper cations to reduce.
For a big volume, I attach the wire to a copper rod.
The copper in solution is usually all removed down to a trace amount within 4 days, unless there's so much copper ion that it totally dissolves the iron anode before finishing. Then a new iron rod is needed to complete the copper reduction.
I'm having a hard time picturing what you are describing here, perhaps you could make a sketch or take a photo of a "battery" like the one you describe.
Thanks
So a big slab or scrap iron with a wire lug on top and a length of insulated copper to get to the other side of a container and attach to a length of copper buss immersed in the solution will do?
I've got a friend hounding me to get rid of drums of spent electrolyte and he doesn't want to do a distillation. I think I'll go downstairs and set up a 5 gallon pail of copper nitrate to try this. He will still have iron in solution to deal with at the end.
I've got a friend hounding me to get rid of drums of spent electrolyte and he doesn't want to do a distillation. I think I'll go downstairs and set up a 5 gallon pail of copper nitrate to try this. He will still have iron in solution to deal with at the end.
If you have the setup, you can also heat copper nitrate solution and bubble the gas released through 20% hydrogen peroxide and regenerate dilute nitric acid.
At a fast boil, copper nitrate will begin to decompose as the solution boils away and becomes more concentrated into copper oxide and nitrogen dioxide at the bottom of the container of solution, where it contacts the heat and passes 180C. This becomes very obvious as it's the same red-brown gas that evolves when nitric is eating at a metal.
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Martijn
Well-known member
It is basically a galvanic cell, like simple batteries work. Two different metals in an acidic solution electrically connected with copper wire outside the solution, creates a voltage. The voltage helps with displacing the copper.
He posted this idea a couple of months ago. Cant find it now though.
Same here. But I am wondering if aluminium does not do the trick. Precipitating all metals. I will see how the ppt will appear, and how the reduction will go - if there wouldn't be much nitrate deep reduction to ammonia. Somewhere I read that even HN3 could be produced in the process, what scares me quite a bit.
I wondered that adding NaCl to the juice in just about right ammount can ppt bulk of Pb as PbCl2. Or even better add H2SO4. Cementation with Fe would then give much cleaner copper. On the other hand, another filtration needed.
My waste is very diluted and contain nearly no Cu, lots of Cd and some SnPb traces. No benefit from recovery, and no possibility to scrubb Cd fumes at the moment. For this canister I will probably go with straight hydroxide, and we will see how things end up. I have regulated filtering unit which can be turned on for days... So if some gooey s..t form, I am prepared
