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

Significance of Proximate Analysis of Coke

The proximate analysis including moisture, volatile matter, and ash content is fundamental for evaluating the quality and performance of coke in industrial applications. Accurate determination of these parameters supports efficient combustion, reliable material balances, and compliance with fuel specifications.

Objectives and Overview of the Study

This application note demonstrates the use of the LECO TGA801 macro thermogravimetric analyzer to perform proximate analysis of coke samples in accordance with ASTM D7582. The goals include establishing method parameters for moisture, volatile matter, and ash determination, calculating fixed carbon by difference, and evaluating repeatability across sample types such as calcined, petroleum, and metallurgical coke.

Methodology and Instrumentation

• Sample preparation followed ASTM D346 procedures using certified reference materials for calibration.
• Proximate analysis performed in three sequential steps: moisture removal at 107 °C, volatile matter release up to 950 °C under nitrogen, and ash determination at 950 °C in oxygen.
• Each step employed preset temperature ramps, hold times, and gas flows to ensure reproducibility.

Main Results and Discussion

• Calcined coke exhibited low moisture (0.14 ± 0.03 %), volatile matter (0.35 ± 0.11 %), and ash (0.79 ± 0.02 %), yielding fixed carbon of 98.86 ± 0.12 %.
• Petroleum coke showed higher volatile content (13.16 ± 0.09 %) and moderate moisture (0.65 ± 0.04 %), with fixed carbon around 86.54 ± 0.11 %.
• Metallurgical coke presented moisture of 1.13 ± 0.06 %, volatile matter 2.31 ± 0.08 %, and ash 11.65 ± 0.03 %, resulting in fixed carbon of 86.03 ± 0.09 %.
• Results demonstrated excellent repeatability (RSDs < 1 %), confirming the robustness of the TGA801 method.

Benefits and Practical Applications

The described TGA801 protocol enables simultaneous analysis of up to 19 samples, reducing turnaround times in QA/QC and research settings. It facilitates accurate fuel characterization for combustion control, material balance calculations, and commercial trading of coke products.

Future Trends and Potential Applications

• Integration of real-time data analytics and machine learning to predict fuel behavior.
• Development of compact TGA systems for on-site monitoring in industrial plants.
• Coupling proximate analysis with evolved gas analysis for deeper insight into combustion mechanisms.

Conclusion

The LECO TGA801 macro thermogravimetric analyzer provides a reliable, standardized approach for proximate analysis of coke. By adhering to ASTM D7582, it delivers precise determinations of moisture, volatile matter, ash, and fixed carbon with high throughput and reproducibility.

Použitá instrumentace

LECO TGA801 macro thermogravimetric analyzer equipped with ceramic crucibles and automated gas control for nitrogen and oxygen atmospheres.

Reference

• ASTM D7582 Standard Test Methods for Proximate Analysis of Coal and Coke by Macro Thermogravimetric Analysis
• ASTM D346 Practice for Sampling and Preparation of Coal and Coke
• ASTM D3176 Standard Practice for Ultimate Analysis of Coal and Coke by Instrumental Methods
• LECO Corporation Application Note, Form No. 203-821-571, Rev. 2, 2020