method and system for regeneration of sulfatelektrolyt in steel - galvanizing.

摘要

Dissolved iron present in a sulphate electrolyte used to coat steel strip is removed by taking part of the electrolyte and adding an oxidising agent to oxidise the iron to Fe3+. The Fe3+ is then precipitated from solution by adding ZnO or ZnCO3-water suspension as the pH is raised. Any excess ZnO or ZnCO3 is dissolved in the electrolyte by adding more fresh electrolyte. The precipitated iron is filtered out and the regenerated electrolyte recycled back to the bath. The apparatus for carrying out the process is also claimed. It comprises a coating cell (20) and means for guiding the strip (40) to be coated through it as well as means (43,44) for producing circulation of the electrolyte through the coating cell. The appts. is novel in that it has a reactions container (2) with a stirrer (8) which is connected to the coating cell (20) of the galvanising bath (15) via a take-off conduit (21) and a return conduit (22). An additional container (4) for oxidising agent having a connecting conduit (26) and a dosing pump (27) as well as a further additional container (3) for a ZnO and/or ZnCO3 water suspension also having a connecting conduit (23) and a dosing pump (24) are connected to the reactions container (2). The dosing pump (24) is actively connected to a pH indicator (30) and the dosing pump (27) is actively connected to a measuring instrument (28) for determining the oxygen content in the electrolyte. A filter (5) for solids is located in the return conduit (22).