Electrolyte Purification

The Steuler Electrolyte Purification (SEP) pr🧸ocess is based on the reduction of chrome(VI) compounds

and extends the lifetime of an electrolyte.

 

For the pretreatment in pickling plants for stainless steel wire an electrolytic pickling process is often employed using a solution of approx. 20% sodium sulfate. The el🍬💞ectrolyte itself is not used up during

this process. Such metals as iron(III), nickel(II) and chrom♓e(III) are precipitated out into the neutral solution as metal hydroxides. To achieve a longer service life for the electrolytes, also the chrome(VI) compounds formed by oxidation, which cannot be removed directly as suspended solids, have to be eliminated from the electrolyte.

 

Process description:
The reduction process is based on the reduction of🍸 chrome (VI) by employing such reduction a𝓰gents

as hydrogen peroxide or sodium bi-sulfite at a low p🎐H value.

 

First there occurs a pH-controlled addition of sulfuric acid to low𒐪er the pH value. At the same time, the reduction agent is dosed rh-dependently to reduce the chrome (VꩵI) to chrome (III).

 

After that, the liquid is neutralized using caustic 𒈔soda and the dissolved metals are precipitated out as metal hydroxides. The particles form flakes, precipitate and are then dewatered in a chamber filter press.
The dose-added caustic soda and sulfuric acid form new electro𒆙lytic solution to compensate for losses in the filter cake water and for those caused by dissipation on the surface of the belt.

 

The main benefits are:
—🌟 High regeneration rate of the neutral𒊎 electrolytes
— Savings in operational costs due to less formation of residue sludge that has to be disposed in the waste water 𝓡treatment plants
— Simple construction of plant and use of tried-and-tested equipm🐈ent