Rinsing water from hardening units, e.g. AS 140, AS 180, Durferrit TF 1, Durferrit REG 1

alkali nitrite, alkali nitrate, alkali cyanide, barium chloride

The rinsing water from hardening units contains a relatively high salt level and can not be directed into the sewerage system without processing. The VACUDEST® units have, as opposed to conventional technology such as chemical/physical treatment, the advantage that the distillate and concentrate can be re-used in the process. Atmospheric evaporators have, in comparison to the VACUDEST® process, low output performance and approx. 10 times higher specific energy requirements and can not work exhaust-free. If the rinsing water contains a larger percentage of slag or particles, then this should be separated before distillation by way of a filter. With the processing of rinsing water which contain barium chloride, a corresponding choice of material for the evaporator is required. Rinse water that contain cyanide can not be processed in the evaporator without a preceding detoxification. A re-use of these salt concentrates is not possible with these salts.

With the distillation of rinsing water one obtains an almost salt-free distillate which one can used as rinsing water. The highly concentrated salt residue from the VACUDEST® vacuum distillation unit can (with nitrite/nitrate salts) be re-used in the hardening bath. If the re-use of the residue only allows the lowest residue water percentages or is not possible, a small external heated evaporator is necessary. Circulation of the distillate and the residue is also possible with the VACUDEST® vacuum distillation units.