Moisture, Volatile Matter, Ash, and Fixed Carbon Determination in Coal (TGA801)

Importance of the Topic

Proximate analysis of coal—measuring moisture, volatile matter, ash and fixed carbon—is fundamental for evaluating fuel quality, combustion performance and material balance in industrial applications. Reliable proximate data guide coal purchasing decisions, boiler design, emission control and adherence to regulatory standards.

Objectives and Overview

This application note demonstrates a standardized workflow for proximate analysis of coal using the LECO TGA801 macro thermogravimetric analyzer. It outlines method setup based on ASTM D7582 (volatile matter), D3176 (ultimate analysis by difference) and D2013 (sample preparation), calibration procedures, sample measurement and calculation of fixed carbon by difference.

Materials and Methods

The workflow comprises three heating stages:

• Moisture determination: ramp from 25 °C to 107 °C at 6 °C/min, hold 15 min under nitrogen until weight constancy.
• Volatile matter: ramp to 950 °C at 45 °C/min, hold 7 min under nitrogen with crucible cover in place.
• Ash content: ramp from 600 °C to 750 °C at 3 °C/min, hold until oxidation under oxygen or air.

Sample preparation follows ASTM D2013 using 0.4–1.1 g of coal, ground and dried. Calibration for volatile matter employs at least three reference materials spanning expected volatile ranges.

Instrumentation

The LECO TGA801 features a 19-position balance, ceramic crucibles with optional lids, precise temperature control and gas flow management. Nitrogen (10 L/min) is used for moisture and volatile steps; oxygen (3.5 L/min) or air (10 L/min) is applied for ash determination. Instrument parameters ensure weight constancy within 0.0005 g.

Main Results and Discussion

Typical dry-basis results for high-volatile bituminous coal showed moisture ~4.7 %, volatile matter ~35 %, ash ~6.8 % and fixed carbon ~58.1 % with standard deviations below 0.1 %. Low-volatile samples yielded moisture ~1.0 %, volatile matter ~17.2 %, ash ~10.9 % and fixed carbon ~72.0 %. Data demonstrate high precision, method robustness and compliance with standards.

Applications and Practical Implications

• Quality control in coal procurement and blending.
• Boiler feed optimization and emission forecasting.
• Reference for carbonization yield and coke quality in metallurgical processes.
• Regulatory reporting for fuel composition.

Future Trends and Applications

Advances may include automated sample handling, real-time data integration with plant control systems, expanded multi-factor analyses (e.g., sulfur content) and miniaturized thermogravimetric platforms for field deployment. Integration of AI algorithms could further enhance calibration and predictive capabilities.

Conclusion

The LECO TGA801 macro thermogravimetric method provides a rapid, accurate and reproducible approach for proximate coal analysis. Adherence to ASTM standards, combined with robust calibration and instrumentation controls, ensures reliable measurement of moisture, volatile matter, ash and fixed carbon for industrial and research laboratories.

References

• ASTM D2013 – Standard Practice for Preparation of Coal Samples for Analysis
• ASTM D3176 – Standard Practice for Ultimate Analysis of Coke
• ASTM D7582 – Standard Test Methods for Proximate Analysis of Coal and Coke by Macro Thermogravimetric Analysis