Carbon and Sulfur Determination in Low Carbon Ferroalloys (CS844)

Importance of the Topic

Ferroalloys are essential for introducing alloying elements such as silicon, manganese, and chromium into steel and cast iron. Precise determination of carbon and sulfur in low carbon ferroalloys is critical for maintaining mechanical properties, preventing defects, and ensuring consistent product quality in steelmaking.

Aims and Study Overview

This study details two combustion-based methods for quantifying carbon and sulfur in low carbon ferroalloys using a LECO CS844 analyzer. Method 1 employs LECOCEL II and iron chip accelerators, while Method 2 uses iron powder, vanadium pentoxide, and LECOCEL to enhance sulfur recovery and precision.

Applied Instrumentation

• LECO CS844 combustion analyzer operated in constant furnace mode at 100% power
• Ceramic crucibles preheated at 1350 °C (20 min) or 1000 °C (40 min)
• Automatic autoloader or manual furnace pedestal
• Accelerators and reagents: LECOCEL II HP, iron chip accelerator, iron powder, V2O5 accelerator
• Certified reference materials (LCRM, NIST ferroalloys and steels)

Methodology

• Analysis settings: purge time 10 s, analysis delay 20 s, integration time 50–80 s, five significant digits
• Sample preparation: 0.25 g of homogenized powder or granules in a preheated crucible with accelerators
• Workflow steps: blank determination, calibration/drift correction with at least three standard replicates, sample analysis in replicates
• Method variants:
  • Method 1: LECOCEL II and iron chip accelerator
  • Method 2: iron powder, V2O5 and LECOCEL accelerator for improved sulfur recovery

Main Results and Discussion

Both methods achieved accurate carbon and sulfur measurements in reference ferroalloys with low relative standard deviations (0.6–1.0  mg C and 0.2–0.4  mg S). Method 2 provided similar precision and slightly enhanced sulfur recovery despite the use of V2O5. Blank stability and linear calibrations forced through the origin ensured reliable quantification across typical concentration ranges (~0.03–0.05 % C and ~0.01–0.03 % S).

Benefits and Practical Applications

• Fast and reliable quality control of ferroalloy feedstocks
• High precision and accuracy for trace-level carbon and sulfur
• Choice of methods based on sample composition and safety considerations
• Compliance with industrial QA/QC standards in steel manufacturing

Future Trends and Application Possibilities

Advancements may include full automation of sample handling, real-time data analysis, and integration with laboratory information management systems. Research into safer, non-hazardous accelerators and miniaturized detection modules could enhance throughput and reduce environmental impact. Machine learning models applied to combustion data may enable predictive quality control and process optimization.

Conclusion

The LECO CS844 combustion methods offer robust, accurate, and flexible solutions for carbon and sulfur analysis in low carbon ferroalloys, supporting critical quality control needs in the steel and cast iron industries.