Total Mercury in Coal and Combustion Residues

Importance of the Topic

Mercury released during coal combustion is a critical environmental and health concern. Accurate determination of total mercury in coal and combustion residues enables emission control, regulatory compliance, and assessment of remediation strategies.

Objectives and Study Overview

The purpose of this study is to present a validated procedure using the LECO AMA254 mercury analyzer for total mercury quantification in coal and related residues. The workflow covers blank determination, calibration, and sample analysis for reference standards and real-world samples.

Methodology and Instrumentation

• Analytical principle: direct thermal decomposition followed by amalgamation and atomic absorption detection.
• Sample mass: 60–80 mg of powdered coal or residue.
• Analysis cycle: 60 s drying, 200 s decomposition, 45 s cell purge, and peak area evaluation.
• Instrument: LECO AMA254 with Quick Mercury Windows software version 2.0.
• Accessories: small nickel boats pre-baked at 400 °C (LECO 614-822-102).
• Calibration standards: LECO fly ash, BCR 143r, NIST 2781 dry sludge, among others.

Main Results and Discussion

The method was tested on certified reference materials and coal samples:

• NIST 1630a (coal standard): average result 0.080 ppm Hg, RSD 6.3%.
• NIST 1633b (fly ash): average result 0.149 ppm Hg, RSD 3.8%.
• Coal sample #1: average 0.112 ppm Hg, RSD 5.4%.
• Coal sample #2: average 0.286 ppm Hg, RSD 6.3%.

Results demonstrate good agreement with certified values and reproducibility suitable for routine analysis.

Benefits and Practical Applications

The described procedure offers:

• Rapid analysis (~8 minutes per sample) without hazardous reagents.
• Minimal sample preparation and operator intervention.
• High throughput suitable for power plant QA/QC and environmental testing.

Future Trends and Opportunities

Potential developments include:

• Automation of sample introduction to increase laboratory throughput.
• Customized calibrations for diverse matrices (soils, sediments).
• Coupling with speciation techniques to differentiate mercury forms.
• Integration into online process monitoring systems.

Conclusion

The LECO AMA254 method provides a robust, efficient solution for total mercury analysis in coal and combustion residues, combining ease of use with reliable performance.

References

No formal literature references were provided in the source document.