Determination of Carbon and Sulfur in Fluorspar (CS844)

Determination of Carbon and Sulfur in Fluorspar: Summary

Importance of the Topic:
Fluorspar (CaF2) is integral to steelmaking, aluminium fluoride and hydrofluoric acid production, and glass, enamel, and cement manufacture. Accurate quantification of impurities such as carbon and sulfur is essential to ensure product quality and process control.

Objectives and Study Overview:
This application note describes a robust analytical procedure using the LECO CS844 Series instrument with halogen trap to determine total carbon and sulfur in fluorspar. It covers sample preparation, calibration, analytical parameters, and performance on certified reference materials.

Methodology and Instrumentation:
A uniform fluorspar powder is prepared by crushing to consistent mesh size and cleaned to avoid surface contamination. Crucibles are pre-baked at 1250 °C or 1000 °C to remove residues and stored in a desiccator. The CS844 furnace operates in constant mode at 100 % power with a 15 s purge, 30 s delay, and specified integration times for carbon (50 s) and sulfur (55 s). A halogen trap kit removes fluorine-derived interferences. Calibration uses low- and high-range steel reference materials (LECO LRM/LCRM or NIST/JK SRMs) with linear forced-through-origin curves. Lecocel II HP and iron chip accelerator are added to blanks, standards, and samples.

Used Instrumentation:

• LECO CS844 Series Carbon/Sulfur Analyzer
• 619-592-150 Halogen Trap Kit
• 528-018/528-018HP Crucibles (baked)
• 502-231 Iron Chip Accelerator
• LECOCEL II HP Reagent

Key Results and Discussion:
Analysis of fluorspar and NIST SRMs yielded highly reproducible data. For one sample batch, carbon averaged 0.242 % (s = 0.004) and sulfur 0.017 % (s = 0.001). A second series showed carbon 0.115 % (s = 0.001) and sulfur 0.079 % (s = 0.001). These results demonstrate excellent accuracy against certified values and stable instrument performance across multiple replicates.

Benefits and Practical Applications:

• Fast, simultaneous determination of total C and S in one run
• Automated calculation of carbonate as CaCO3 equivalent
• Effective fluorine removal with halogen trap, minimizing flow restrictions
• Straightforward calibration using widely available CRMs

Future Trends and Potential Uses:
Advances may include integration with autosamplers for higher throughput, adaptation of the method to other mineral matrices, development of enhanced trap materials for broader halogen removal, and digital data analytics for real-time quality control.

Conclusion:
The LECO CS844 with halogen trap offers a reliable, precise, and efficient solution for total carbon and sulfur analysis in fluorspar, supporting stringent quality requirements in industrial applications.

References:
LECO Corporation. Determination of Carbon and Sulfur in Fluorspar, Application Note Form No. 203-821-509. 2017.