Fluorine in coal sample applying Metrohm Combustion IC according to ASTM D8247

Importance of the Topic

Coal often contains fluorine compounds that generate corrosive hydrofluoric acid during combustion. Controlling fluorine levels in coal is critical for thermal power plants to minimize equipment corrosion and environmental hazards.

Objectives and Overview of the Study

This study aims to quantify fluorine in coal samples using a validated ion chromatography method following pyrohydrolysis. The approach is aligned with the ASTM D8247 standard and integrates Metrohm Combustion IC technology to achieve precise and reliable results.

Methodology

The coal sample is subjected to pyrohydrolysis at high temperature in an inert atmosphere. The released fluorine is trapped in an absorbent solution and analyzed by ion chromatography. Key analytical parameters include a 1100 degree Celsius combustion temperature, an oxygen flow of 300 milliliters per minute, and a partial loop injection technique to enhance sensitivity.

Used Instrumentation

• Metrohm 930 Compact IC Flex with conductivity detector
• Combustion module with oven and absorber block
• Partial Loop Injection Technique with Inline Matrix Elimination
• Columns: Metrosep A Supp 5, Metrosep A PCC 1 HC, Metrosep A Trap 1, and Metrosep I Trap 1
• Autosampler MMS 5000

Main Results and Discussion

Fluorine was detected at 87.9 milligrams per kilogram in the tested coal sample. Chlorine was measured at 55.8 milligrams per kilogram, while sulfur remained below quantification limits. The method demonstrated high repeatability and low detection limits, ensuring compliance with industrial quality requirements.

Benefits and Practical Applications

• Accurate quantification of fluorine supports selection of low-corrosivity coal.
• Robust method for routine quality control in power plants and coal suppliers.
• Minimized downtime and maintenance costs through early detection of high fluorine levels.

Future Trends and Opportunities

Advances may include coupling with mass spectrometry for speciation, further miniaturization of combustion units for field use, and integration with real-time monitoring systems to provide continuous feedback during coal handling and combustion.

Conclusion

The presented method offers a reliable and standardized procedure for determining fluorine in coal. Its adoption can enhance safety, reduce corrosion, and improve operational efficiency in thermal power generation.

References

• ASTM D8247 Standard Test Method for Determination of Fluorine in Coal
• Metrohm Application Note CIC 20 Version 3 March 2020