Flue Gas Desulfurization

This process is used in the coal thermal plants or oil thermal plants to remove the SO2 (sulphur dioxide) contained in the combustion fumes and to avoid to release it in the atmosphere.
The SO2 causes acid rains.

Gas leaving the oven go through a filter to remove the coarse particles. To catch the sulphur contained in the flue gas, calcium carbonate (or lime) grinded very finely is pulped and then injected in tanks. The hydrocyclones are used in the carbonate grinding circuits.

When the flue gas cross this CaCo3 solution, the sulfur reacts with the calcium carbonate to form gypsum, CaSO4. Desulphurised gas are then released in the atmosphere.

Water containing gypsum and calcium carbonate is then reprocessed to be reused. Reprocessing needs using hydrocyclones to separate the solids gypsum particles and the water. The gypsum particles are concentrated at the hydrocyclone's underflow and water process, cleared from gypsum, is released at the hyrocyclone's overflow then is recycled in the process. Gypsum is then filtered to remove residual water.

A wide range of hydrocyclones enabling to process all the flows and to meet any grain cut sizes.
We have many references in South Korea, France, Poland, in grinding circuits or gypsum separation.

The hydrocyclones are used :

- In the carbonate/lime grinding circuits : the too coarse particles are separated by the hydrocyclone and reintroduced in the crusher.

- In the gypsum separation of process waters : the hydrocyclones enable to concentrate the gypsum and to thicken the pulp before filtration. Water released at the hydrocyclones' overflow returns in the process.