CHROME Recovery Plant (Tanneries)

As the world has become more concerned about the environment, there has been an increase in the application of evaporator systems to waste water treatment. These types of evaporators essentially reduce the volume of the waste by removing/recovering most of the water in the waste. In some applications, the concentrate contains product of value, which can be sold or further processed in a dryer to a solid product. In cases where the product has no value, the concentrate can be dried and the resulting product buried in a landfill. Since the condensate from these evaporators is usually quite pure, the water that is recovered can be used as boiler feed, as rinse fluid for cleaning or merely disposed into the sewer or directly into a river.
As with the processing of any waste product, there are usually severe cost restraints since, unless forced by regulation, few organizations wish to spend valuable capital on waste treatment processes. The equipment therefore has to have both low capital and operating costs.
RAFAE Engineering partners with you to provide the best solutions for treatment of industrial wastewaters. As one of the leading designers and manufacturers of thermal and mechanical process equipment with core competence in evaporation, crystallization, vacuum and heat transfer, RAFAE Engineering offers custom made plants with additional upstream or downstream process steps. Suitable combinations of processes in our plants achieve optimum results for the recovery of water and valuable products.

About Chrome Recovery:

It is observed that 25-30% of applied chrome remains unconsumed and drained out as effluent. Adoption of chrome recovery in case of raw hide to finished processes should be practiced the tanneries. It is possible that 90-95% of unconsumed chrome can be recycled. It comprises of collection of spent chrome liquor and recovery of chrome from the same. Savings can be obtained from the process, by a reduction of 20% of the chromium used and substantial reduction in the amount of salt used.
The Chromic Acid, recovered from the Chrome Recovery System has strength of about 5-6 g/l Cr2O3. It needs to be concentrated up to 10 g/l for addition into the main re-chroming drum. For this, a Chrome Evaporator, which is most energy efficient, is recommended.
It operates in relation to the principle of evaporation. Based on our experience we have selected the evaporator type as Forced circulation design single stages Evaporation Plant with an automatic operation sequence, suitable for the continuous concentration and reuse of residual chrome liquor solution for reuse and simultaneous hot water generation. This is most suitable design for water recycling from waste water. The self cleaning effect due to suppressed boiling at heat transfer surface eliminate the risk of scaling in heat exchanger and cleaning interval is much increased as proved in our several installations in other applications.
The heating medium can be fresh steam as well as waste heat, flash steam, hot water etc. The evaporated water is condensed in condenser thus generating hot water for reuse in other processes in the factory.