Why can sulfur in coal affect its suitability for a particular use?

The sulfur content in coal is a critical factor in determining its suitability for various applications due to both environmental regulations and technical requirements.

• Environmental Impact: When coal is burned, sulfur is released as sulfur dioxide, a pollutant that reacts with atmospheric moisture to form sulfuric acid. This contributes to acid rain, which damages buildings, crops, and ecosystems. Consequently, strict air-pollution regulations often mandate the use of low-sulfur coal or the installation of expensive cleaning devices like scrubbers at power plants.1234
• Industrial Suitability: For the production of metallurgical coke—essential for smelting iron ore—only bituminous coals with a relatively low sulfur content are suitable. High sulfur levels can negatively affect the quality of the final metal product.15
• Advanced Combustion: While high-sulfur coal is generally problematic, fluidized-bed combustion systems are specifically designed to handle it. By adding limestone to the combustion bed, the sulfur dioxide can be captured and converted into solid calcium sulfate, mitigating emissions.6