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
