Electrochemistry whats on my cathode?

[silvergoblin]

been running a sulfuric cell for a few days on misc pieces....
after a while, i can see the gold floating around but my cathode gets covered in a brown mud....is this copper or gold?

as I understand it, the copper should form copper sulphate if/when the temp gets too high...but that is a blue goop, correct?

I have been saving this brown mud along with the rest of the floaties....

Is there a way to determine gold or copper quickly at this stage?

 

[silvergoblin]

sorry cathode lead...conc sulfuric electrolyte....12v pulling approx 6 amps...anode is the part to be stripped

 

[publius]

Are you using concentrated Sulfuric Acid or the Copper Sulfate electrolyte? Both can be used to recover gold.

 

[silvergoblin]

it started as concentrated sulfuric...but has an emerald tint now after several uses

 

[publius]

Sulfuric acid is hydroscopic. It is used to dehydrate things. You may have used diluted H2SO4, Hence the green or blue tint.

 

[Geo]

if you dilute the acid safely with 4X water and then evaporate back to concentrated status of the acid, the impurities will precipitate out as green crystals.

 

[FrugalRefiner]

hygroscopic.

Dave

 

[goldsilverpro]

I would guess that about 90% of the problems that people have with the sulfuric stripper are because they use too much current and the solution gets too hot. I never let it get above about 110-120F. To me, the absolute worst possible power supply for the sulfuric stripper (or, for ANY other electrolytic system) is a battery charger. You need a variable PS that you can control.

There are ways around this. You could place the stripping tank in a cool water bath, you could add a resistance to the system, or you could run fewer parts at one time. You could also use a larger tank and limit the amps to about 8A per gallon of solution.

 

[silvergoblin]

if you dilute the acid safely with 4X water and then evaporate back to concentrated status of the acid, the impurities will precipitate out as green crystals.

this precipitation takes place by the addition of water alone or during concentration ?

so Im guessing that I have quite a bit of copper at the cathode...

 

[publius]

Snip...

this precipitation takes place by the addition of water alone or during concentration ?

so Im guessing that I have quite a bit of copper at the cathode...

As the water evaporates the crystals will grow.

 

[lazersteve]

A normal manual battery charger's voltage can easily be controlled using a common variac transformer rated for the maximum amperage that the charger with draw. Simply plug the power cord for the battery charger into the variac and adjust the voltage output voltage to the desired level.

Amazon Variac 4 sale

Steve