Regeneration Of Invar Etching Liquid By Paired Electrolysis Technology

This dissertation is focused on the regeneration of invar etching liquid by paired electrolysis technology. Instead of traditional chemical reagents for oxidation and reduction, the exchange membrane of weak base anions was applied as electrolytic component with clean energy of electrons, thus avoiding using a lot of iron and harmful byproduct chlorine gas.The electrode materials, electrolytic cell structure, and current density for electrolyte composition were optimized. It was demonstrated that the scale-up production can be realized by paired electrolysis technology. The continuous and automated process was established as follows:1) titanium dioxide-based ruthenium as the anode, titanium material as cathode, assembled with paired type; 2) current density at 600 A/m, electrolysis temperature at 30-70℃, space velocity 5at -10 cm/s; 3) total cathode iron concentration at 150 g/L, iron ion concentration at 9-10 g/L; 4) total anode iron concentration at 160 g/L, ferrous ion concentration at 50-60 g/L.The nickel ion process can be reduced with industrial production of iron powder at the temperature of 95-100℃. A continuous, graded process in series was applied to remove nickel ions. The iron powder can be recycled at the end. The applied quantity of iron is 1.5 times as the total nickel content, being capable of realizing iron-nickel alloy with nickel content up to 50%.The regeneration component of etching liquid content is FeCl3 (45-48%), FeCl2 (< 0.2%), NiCl2 (<0.1%), meeting the quality requirement of recyclization. Moreover, the investment project with 10,000 T/Y can be recovered in half a year, generating considerable economic benefit.