Investigation of Product Properties and Reaction Mechanism of Low-Rank Coal Pyrolysis with Phosphorite in a Fluidized Bed

This study investigates the co-pyrolysis of low-rank, high-alkaline coal with phosphorite to enhance resource utilization and mitigate equipment corrosion caused by alkali metal emissions during the thermal processing of high-sodium coal. Pyrolysis experiments were conducted in a fluidized bed reactor, with different temperature and phosphorite ratios. The results demonstrate that the interaction between phosphorite and coal macromolecules can promote the decomposition of aromatic compounds. At 700 degrees C, after adding 15 % phosphorite, the yields of char and gas of Naomaohu coal (NM coal) increased by 3.14 % and 0.65 %, and the yield of tar decreased by 5.29 %. Meanwhile, compounds such as calcium, aluminum, and silicon contained in phosphorite react with Na and Cl to inhibit the release of corrosive substances. At 900 degrees C, after adding 15 % phosphorite, the release ratios of Na and Cl decreased by 15.67 % and 16.05 %, respectively. The changes in the pyrolysis products of Hami coal (HM coal) are consistent with those of NM coal. Calcium fluorophosphate and calcium phosphate in phosphorite can react with alkali metal chlorides and sulfides to form phosphates that are more easily reduced. The use of recycled phosphorite enhances both the conversion ratio and product quality in yellow phosphorus production. This method not only improves the quality of pyrolysis products but also optimizes the thermal utilization of high-alkali coal and phosphorite, providing a cost-effective and efficient approach for resource utilization.