Cadmium removal from phosphoric acid
Regulatory agencies in many parts of the world are setting increasingly strict limits on the amounts of heavy metals permitted in the food chain. This has led manufacturers of phosphoric acid to seek cost-effective methods to remove heavy metals such as cadmium, arsenic and others from their products.
Syensqo has developed a unique suite of reagents, ACCO-PHOS® promoters, for the removal of cadmium from phosphoric acid. In contrast to alternatives like calcination or solvent extraction, ACCO-PHOS® promoters:
- Are cost-effective
- Consumes little or no energy during its application
- Are easy to use
- Do not disrupt existing production processes
- Do not require changes in the plant's infrastructure
- Can be used to reduce relatively high cadmium levels
Application of ACCO-PHOS® promoters
This product is typically applied as a ten percent solution of the reagent, diluted with industrial process water, free of Cd and Cu ions. For removal in the filtration section, it should be added through a feed pipe to the slurry line between the attack tank and the filter allowing for a mixing time of at least 30 seconds. The dosage depends on the amount of cadmium and other metals present. Typical application dosages of ACCO-PHOS® promoters are in the range of 1-5 kg per tonne of P2O5. On reacting with the ACCO-PHOS® promoters, cadmium quickly forms an insoluble complex that may be removed by filtration or other separation processes. In laboratory tests and field applications, ACCO-PHOS® promoters have reduced cadmium levels to 95% of initial values in 54 percent phosphoric acid.
The cadmium removal process described above is inherently flexible and adaptable to a variety of operating conditions. Contact your Syensqo representative for further details.
Additional information regarding ACCO-PHOS® can be found here:
Link to Whitepaper
Link to ACCO-PHOS webpage