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ReKAT Cation exchanger
for the purification of chrome baths, etching baths, and other chrome-containing solutions
Description of plant
The standard RECAT I and RECAT II systems are compact, economical cation exchange package systems for the removal of metallic contamination from chrome solutions. They are available in two sizes.
Chromic acid recovery can be practiced by simple counterflow rinsing and dragout recovery, or with one of our well-known recycling processes, such as rinse water evaporation or the scrubbing of chrome tank exhaust air. This recycling practice can attain up to 100% recovery. However, the higher the recovery, the higher the content of metal impurities and trivalent chrome; thus, the solutions have to be purified to keep within acceptable operating parameters.
Chromic acid solutions with concentrations of up to 80 to 100 g/l of CrO3 can be purified with this strongly acidic cation exchanger, by removing the troublesome metal ions. Any of the etching baths that have a build-up of iron can also be included in this purification loop. Every hour, a few liters of process solution are removed from the chrome or the etch tanks; this volume is then diluted with rinse water before being pumped through the strongly acidic cation exchanger for purification. The purified chromic acid solution may then be used to make up evaporation losses. Where high dragout rates prevail, which can amount to several times the chrome bath volume per year, only the rinses have to be purified. However, it is important for the ion exchanger to remove sufficient metallic impurities to balance the metal impurity build-up within the chrome tank and maintain the electrolyte within acceptable operating tolerances.
The strongly acidic, macroporous cation exchange resin KC 3 has a high porosity and a large adsorption capacity at a high velocity of reaction. It also stands out for its excellent mechanical stability and resistance to oxidation. The KC 3 resin tolerates chrome concentrations from 80 to 100g/l (as CrO3), with minimum degradation of the resin matrix and a sufficiently low counterion effect, so that a usable volume capacity of approximately 1 val/l can be attained.
Advantages
- No more dumping, detoxification, and fresh makeup of new chromic acid solutions, because of contamination with metal impurities
- Chromic acid recovery through removal of metallic contaminants, using strongly acidic cation exchangers
- Reduction of excessive Cr3+ build-up
- Concentration and volume reduction of the purified chromic acid solution with our chrome recovery process (no external energy needed) possible
- Easy retrofit into existing installations; minimum floor space required
- Can also be used to regenerate chromating solutions
- System design employs cutting-edge control technology, with Festo valve rack, plus Siemens PLC and operator control display
- Fully automatic package systems, including regeneration tank and the initial resin fill; all components are mounted in a stainless steel frame
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German
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