Retention of As during coal combustion: Devolatilization and char combustion

The retention of arsenic (As) during coal combustion facilitates As emission control. A fixed-bed experimental system was used to conduct devolatilization and char combustion experiments at 1100-1300 ? using three types of coal. Both processes contributed to the As release. As in coal was bound to carbonate, oxide, sulfide, and aluminosilicate (Als-As). During devolatilization, carbonate-and oxide-bound As and Als-As remained stable, while sulfide-bound As was completely decomposed. The gaseous As was partially retained as Char-As. During char combustion, Char-As was oxidized to As2O3, which was partially retained by minerals. Carbonate-and oxide-bound As reacted with silicon (Si) and aluminum (Al) to produce Als-As, which was the main As form in ash. As retention was significantly inhibited by the destruction of the lattice structure. As retention by char during devolatilization and minerals during char combustion promoted As enrichment in solid products and its removal.

Automated summary

The retention of arsenic during coal combustion is important for controlling its emissions. Both devolatilization and char combustion processes contribute to the release of arsenic, with a portion being retained as gaseous form and another portion being retained by minerals in solid products.