Ayham Hafez
Well-known member
Thanks a lot, you alright, I didn't notice the DC/AC option
Electrolytic copper refining cell
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Ayham Hafez
Well-known member
I'm trying to find a way to prepare about 110 liters of copper sulphate solution that contains about 5 kg of pure copper, in local market we have only copper sulphate fertilizer which seems not pure, and since I have pure copper stock (wires and tubes) I decided to prepare the copper sulfate myself, tried to make small experiment using electrolysis method but I found out that its easier to use nitric acid as an oxidizer, so I'm planning to go with this recipe for dissolving each 1 kg of copper:
696 ml 68% HNO3
860 ml 98% H2SO4
4,000 ml water, to avoid making cupper sulphate crystals on the surface of the copper pieces so reaction will not stop till consume all nitric and sulphuric acids, at the end I need the copper sulphate to be fully dissolved for the electrolyte.
The reaction equation:
Cu + HNO3 => Cu(NO3)2 + NO2 + H2O
Cu(NO3)2 + H2SO4 => CuSO4 + 2HNO3
So after reaction finished I will get free nitric acid about half first used amount.
Since quantity is a bit large, denoxing using evaporation method is not accepted, so I have one accepted way to denox nitric acid which is using Sulphamic acid.
Is using Sulphamic acid in the electrolyte is OK? and how I can measure free H2SO4 in the solution after using Sulphamic acid, or its doesn't matter just add sulphuric acid till I reach the required amps later when I run the cell?
696 ml 68% HNO3
860 ml 98% H2SO4
4,000 ml water, to avoid making cupper sulphate crystals on the surface of the copper pieces so reaction will not stop till consume all nitric and sulphuric acids, at the end I need the copper sulphate to be fully dissolved for the electrolyte.
The reaction equation:
Cu + HNO3 => Cu(NO3)2 + NO2 + H2O
Cu(NO3)2 + H2SO4 => CuSO4 + 2HNO3
So after reaction finished I will get free nitric acid about half first used amount.
Since quantity is a bit large, denoxing using evaporation method is not accepted, so I have one accepted way to denox nitric acid which is using Sulphamic acid.
Is using Sulphamic acid in the electrolyte is OK? and how I can measure free H2SO4 in the solution after using Sulphamic acid, or its doesn't matter just add sulphuric acid till I reach the required amps later when I run the cell?
Non concentrated Sulfuric should be enough.
Hot Sulfuric at 10%+ should do the job.
Why mix in something else if you want it be pure?
Ayham Hafez
Well-known member
I read different articles about preparing the copper sulphate electrolyte, most of them use less than 45 grams of copper per liter (about 34 grams) and much more less than 200 grams of sulphuric acid per liter ( one experiment they use only about 45 grams per liter).
If we use less/more copper in the electrolyte than required, will the cell once run dissolve copper from anode into the electrolyte to reach the required copper level (or plating copper on cathode in case we use more copper)? What's the effect of using less/more copper than needed?
Same question about sulphuric acid, what will happen if we use less/more needed amount of sulphuric acid? Is it better to add sulphuric acid till we reach to the required current (amps) regardless the final quantity?
If we use less/more copper in the electrolyte than required, will the cell once run dissolve copper from anode into the electrolyte to reach the required copper level (or plating copper on cathode in case we use more copper)? What's the effect of using less/more copper than needed?
Same question about sulphuric acid, what will happen if we use less/more needed amount of sulphuric acid? Is it better to add sulphuric acid till we reach to the required current (amps) regardless the final quantity?
Correction, it seems it is produced by hot concentrated Sulfuric or from Oxide with hot dilute acid.
Ayham Hafez
Well-known member
Not understand you please explain. Do you mean dissolve copper in dilute sulphuric acid without an oxidizer? Or you are talking about making copper sulphate using electrolysis method?
The production of Copper Sulfate is done by hot concentrated Sulfuric and Copper, or Dilute Sulfuric acid from Copper Oxide.
Ayham Hafez
Well-known member
I think, Price + nitrate will dissolve silver and palladium, that mean extra work.
Ayham Hafez
Well-known member
I don't have access to copper oxide, and don't know about the effecienty of producing copper sulphate using hot concentrated copper, did you test it? Is it take long time to dissolve copper into hot concentrated sulphuric acid?
I tested it only with wet ashing ic chips, but not noticed how its effective.
You mean hot concentrated Sulfuric I guess.
I think we are talking about temperature well below what is needed for wet ashing.
If we run a Sulfuric stripping cell too hot it will dissolve the Copper mesh.
But the same will happen if the Sulfuric is below 90% in concentration.
So my guess will be somewhere around 100 150C.
And no I have had no need for a Copper cell yet and even less Copper Sulfate.
If you can get impure Copper Sulfate you can dissolve it and let it re-crystalize and sort out the pure Copper Sulfate,
it will be labor intensive but an option.
What kind of impurities do it have?
Ayham Hafez
Well-known member
I didn't check the impurities, but from the shape of it its not clean, also very expensive comparing to the copper wires 99.9 price in my local market, so its much more good for me to make copper sulphate myself.
Now am trying to make a research about how factories produce copper sulphate, before long time I asked Chinese company that provide copper sulphate factories equipment to send me a technical proposal, their equipments were stainless steel 316L tanks and heaters, when asked them about how much sulphuric acid we need they sent me this recipe:
For 2 ton per day, the consumption will be:
0.5 ton copper per day
0.7 ton water per day
0.8 ton sulfuric acid per day
The electricity consumption is about 200KWh per day
Electricity is for heating cause they didn't talk about any anode baskets to use electrolysis method, I think even dilute sulphuric acid with high heat will also dissolve copper, I think they use lining for the stainless steel reactor cause SS316L also dissolved in hot dilute sulphuric acid
In my mind your are making a chemical copper chemical soup. I simply take dilute Sulphuric Acid ( Battery Acid ) that I buy at an Auto-spares Shop.
Do a small quantity to prove the concent. Copper will not disslove in Plain dilute Sulphuric Acid, but when you add a few drops of Hydrogen Peroxide
then the it will disolve Copper. My copper sulphide Electrolyte contains 300 grams per liter of Sulphuric acid. 5Kg Cu/ 110 Lt equates to 45.4545grams per liter. The beauty is Minimum chemicals in volved.
Ayham Hafez
Well-known member
Hydrogen peroxide is too expensive and unstable to use it as an oxidizer to make copper sulphate.
I will not use 300 grams of sulphuric acid per liter, will use as recommended 170 to 200 grams per liter.
I bow to your superior knowledge. If a couple of drops of H2O2 is to expensive. One could use a combination of (1) Battery charger, (2) Battery Acid,
(3) Copper Anode, and (4 ) an Inert Cathode. To make Copper Sulfate solution
Ayham Hafez
Well-known member
With couple drops of H2O2 35% concentration even with couple tens milliliters you can't oxidize more than 1 gram in case all H2O2 reacted to the metal itself, I tested it many times, H2O2 consumed very quickly before hitting the metal.
With electrolysis method, you need to make cathode far enough from anode to avoid copper ions forms onto the cathode surface. I tried to prepare 200 liters barrel with copper tubes as anode and cathode to dissolve the 5 kg of copper but I found it very hard to be done.
Copper sulphate produced industrially using air bubbler and boiling reactors, that also make me be far from using electrolysis method.
Ayham Hafez
Well-known member
I think the best way for me is to use nitric as oxidizer, but how should I get rid of nitric after finish forming copper sulphate without evaporating the solution and form copper sulphate crystals?
Martijn
Well-known member
You could freeze the liquid and decant it once you have crystals and reuse the nitric/CuSO4 solution to make more copper sulfate.
But evaporating before converting all copper nitrate to copper sulfate can help the conversion.
Why are you determined to use nitric? If you do you need to figure out how to separate copper nitrate from copper sulfate. Have you considered oxidizing your copper first, before sulfuric usage? Once it turns that greenish color then add it to sulfuric. Or look for copper sulfate in other forms. Here it is used to kill roots in septic systems and can be found in most home repair stores. Reading the ingredients in home use chemicals can be a real eye opener at times.
Here is an idea, make a gold stripping cell and run it with no gold. If it heats up sulfuric will put copper into solution.
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