# Problem with titanium basket in electrolytic silver cell



## BrK (Jan 3, 2013)

Hi 

I have a problem with titanium basket, during the silver electrorefining process, in the areas where basket is welded, (picture below) there appears black thin crystals and they are growing quite fast during the process. We suspect this black pins like crystals are tytanium from basket. These crystals escape filter, even

Here are process's parameters:
Vertical cell
Current: 3 A, 3 V
Duration: 3 hrs
Rectifier model: Mastech HY3030E-VARIABLE POWER SUPPLY 30V 30A
http://www.mastechpowersupply.com/dc-power-supply/switching-power-supply/mastech-variable-power-supply-30v-30a-hy3030e-900w-high-current/prod_19.html
(as far as I know this models ending with E are not recommended for electrolysis)

Switching Mastech Models recomended for elecrolisys end with symbol EX or D are:
http://www.mastechpowersupply.com/dc-power-supply/switching-power-supply/cat_7.html
They are called Switching Power Supply rectifiers

Electrolyte: AgNO3 (670 gr/12 litres), pH ~ 3
Anode measurements: 12,5 cm x 4 cm x 0,8 cm
Cathode measurements (stainless steel): 11,5 cm x 13,5 cm x 0,2 cm
Distance between anode and cathode: ~ 5 cm
Process yield: 10 grams / 1 hour
Anode purity: ~ 99 %
Filters: 1 inside coffee filter + polypropylene outside filters (used 10 microns or 50 microns, already)
Basket weight: before process: 64,8 gr. / after: 64,6 gr.
Do I use wrong rectifier, variable vs switching????? Or any other variable is wrong.
Photos:


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## BrK (Jan 25, 2013)

ok... I know what is it - AgO, standard potencial of Ag2+/Ag+ is about ~1,9 V and above this potencial I can observe those black cristals growing really fast on the titanium basket. They have diamagnetic properties and quickly dissolve in ammonium. During heating those cristals turn into black powder (Ag2O) which is not good soluble in ammonium as crystals (because of its alkaline properties). When I add HCl to the solution there appears white sludge of AgCl.

Anyone has similar problem ?

How can I avoid this secondary reaction ?


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## Palladium (Jan 25, 2013)

I tried Ti wire when i first started messing with my silver cell. I got the same type of crystal formations. I don't know what it was but i got tired of fighting it and switched to using a silver rod that i pour to make the electrical contact with the bars. I have never been happier with the results then after using the bar method and not Ti. Their is only two things i want touching my silver or my silver solution to guaranty i get high purity and that is the stainless cathode and the silver dissolving into it. Anything else is a recipe for trouble to me.


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## BrK (May 28, 2013)

works fine without titanium baskets, bigger version [youtube]http://www.youtube.com/watch?v=L-mB0-BjjRA[/youtube] but not final, still thinking about adding 3 more anodes (850 g. each) to improve daily yield :wink: cheerz


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