Carbon and Sulfur Determination in Low Carbon Ferroalloys (CS744)

Importance of the Topic

Control of carbon and sulfur content in low carbon ferroalloys is essential for steel and cast iron production. Carbon serves as the primary alloying element impacting mechanical properties, while sulfur acts as a contaminant that degrades strength and ductility. Reliable determination of both elements in ferroalloy feedstock supports quality assurance and process optimization in metallurgical operations.

Objectives and Overview

This study presents two combustion-based analysis methods for simultaneous determination of carbon and sulfur in low carbon ferroalloys using the LECO CS744 analyzer. The aim is to compare the performance, precision, and practicality of Method 1, which employs LECOCEL II and iron chip accelerators, with Method 2, which uses iron powder, vanadium pentoxide, and LECOCEL accelerators.

Methodology and Instrumentation

Sample preparation involves obtaining a homogeneous powder or granular sample and loading 0.25 g into preheated ceramic crucibles. Two distinct accelerator combinations promote efficient combustion:

• Method 1: 1.2 g LECOCEL II plus 0.8 g iron chip accelerator
• Method 2: 0.4 g iron powder, 0.6 g V2O5 and 1.5 g LECOCEL

Key analysis parameters include a 10 s purge time, 20 s analysis delay, furnace power at 100 %, and integration times of 40–70 s. Calibration and blank determination are performed using certified reference materials such as NIST 58a, ferroalloy, and steel standards. Ceramic crucibles are heated at 1350 °C for 20 minutes or 1000 °C for 40 minutes, then stored in a desiccator to maintain precision.

Main Results and Discussion

Both methods achieve precise carbon and sulfur measurements in various ferroalloy matrices. Method 1 yields an average of 0.089 % carbon and 0.0298 % sulfur for ferro-vanadium with standard deviations of 0.001 % and 0.0005 %, respectively. Method 2 reports similar carbon precision (0.088 % ±0.002 %) and slightly improved sulfur recovery (0.0315 % ±0.0003 %). Low blank values and consistent linear calibrations forced through the origin demonstrate suitability for routine QA/QC applications. The inclusion of V2O5 in Method 2 enhances sulfur detection but requires management of a hazardous accelerator component.

Benefits and Practical Applications

The described methods provide rapid, accurate, and reproducible carbon and sulfur determinations in low carbon ferroalloys. The choice between Method 1 and Method 2 depends on laboratory safety policies, available accelerators, and desired sulfur sensitivity. Routine implementation on the CS744 supports metallurgical feedstock evaluation, alloy quality control, and compliance with industry specifications.

Future Trends and Opportunities

Advances in combustion analyzer technology and automated sample handling will further streamline multi-element analysis in complex alloy matrices. Development of non-hazardous accelerators with high sulfur recovery rates could replace V2O5. Integration of real-time data processing and machine learning algorithms may improve calibration stability and predictive maintenance of the CS744 system.

Conclusion

LECO CS744 methods employing different accelerator combinations offer reliable carbon and sulfur analysis in low carbon ferroalloys. Method 1 provides a straightforward, non-hazardous approach, while Method 2 enhances sulfur precision at the expense of using a hazardous accelerator. Both yield reproducible results suitable for industrial quality control.

References

• LECO Corporation. Application Note Carbon and Sulfur Determination in Low Carbon Ferroalloys Form No. 203-821-565 December 2018 Saint Joseph Michigan USA