In The Netherlands, the cost of waste disposal is increasing fast. Moreover, government policy forces companies to research, develop and implement new techniques aimed at the recove-ry of the waste streams they produce. WTN Water Treatment reacted very early on this new trend in de-veloping new techniques to remove Pb from hydrochloric acid pickling baths, without producing any addi-tional waste products.
The WTN - RePb process of-fers several major advantages:
It has been developed by and for galvanizers
It is a flexible process.
It involves very low disposal costs
No extra manpower is required
It represents a saving on basic chemical cost
The lead is remove continuously with ion exchange technology. After the Pb is removed out of the pickling acid is will be absorbed on the ion-exchange col-umn. Removing of the PB from the ion exchanger is required with a stripping solutions resulting is a diluted PbCl2 solution. Afterwards the stripping solu-tions can be treated by a. filtration or b. electrolytical precipitation producing metal Pb.
The principles of this unique ReZn-process, which produces a basic flux component out of a waste pickling acid, are described below.
Process description
The ion-exchange material, specially developed for the RePb-process, sepa-rates Pband Fe in a highly selective way. The process is divided into 4 stages:
1. Loading phase.
After filtration of solid particles with a plate-filter lead is separated from the pick-ling acid and absorbed by the special ion-exchange material. Lead-free pickling acid is pumped back into the pickling bath.
2. Rinsing phase
After saturation of ion-exchange material with lead, it is rinsed to remove any re-maining pickling acid.
Rinse solution later be used to adjust the concentration of the pickling bath.
3. Stripping phase
Lead is stripped from the ion-exchange material with stripping solution.
The unit can be supplied fully skid-mounted and is able to run fully auto-matically, if desired controlled by WTN
