The SOLVAir® RSC* Recycling Solution reduces the amount of residues to be landfilled by a factor of 10 or more by extracting a salted solution and replacing the original raw materials of chemical processes.
* Residual Sodium Chemicals
In air emission control with double filtration of waste to energy plants, the RSC collected at the second filter consist mainly of sodium chloride, sodium sulfate and sodium carbonate. These products are contaminated by impurities like: fly ashes, activated carbon, heavy metals, micro pollutants, etc.
Residuals produced by the air pollution control processes are considered as harmful substances.
The SOLVAir® Solution: recycling process for sodic residue of flue gas cleaning
SOLVAY has developed and patented an original technology which allows the production of purified sodium brine suitable to replace the natural brine used in soda ash production plants. Resolest® in France and Solval® in Italy, have successfully industrialized this technology since 1998.
The RSCs are dissolved in water at a controlled PH, with additives, and filtered. The insoluble part, containing fly ashes, activated carbon and heavy metals hydroxides, is removed as a filter cake.
The raw clear brine passes trough a column of activated carbon in order to eliminate residual organic matter. The last traces of heavy metals are removed by treatment using ion exchange resins. The purified brine is then reused in soda ash manufacturing.
The process avoids the production of liquid effluents; all the washing water and resin regeneration fluids are reused in the process. The filter cake (representing only 2 to 4 kg/t final waste) is landfilled in an authorized disposal.