Carbon and Sulfur in Metal-Bearing Ores and Related Materials (CS744)

Significance of the Topic

Quantifying carbon and sulfur in metal-bearing ores is essential for controlling metallurgical reactions and for environmental monitoring of mining waste products. This information helps optimize process kinetics, acid consumption, and gold recovery efficiency.

Objectives and Study Overview

This application note describes a method using the LECO CS744 to determine total carbon and sulfur in metal-bearing ores. The study outlines instrument setup, calibration, sample preparation, and analysis procedures, and presents typical performance data.

Methodology and Procedure

The method utilizes a combination of pyrolysis for sulfur determination and acid digestion for carbon measurement, relying on acid/base accounting based on mineral stoichiometry. Key steps include:

• Sample preparation: drying samples at 105°C for 1 hour or moisture correction; grinding to 150 µm.
• Blank determination: analysis of accelerator-only crucibles to establish baseline signal.
• Calibration and drift correction: using NIST SRMs and LECO synthetic and ore calibration materials with replicate analyses.
• Sample analysis: weighing 0.2–0.25 g sample into preheated crucibles, adding carbon and sulfur accelerators, and analyzing under standardized instrument parameters.

Used Instrumentation

The analysis was performed on a LECO CS744 carbon/sulfur analyzer. Accessories included:

• Ceramic crucibles baked at 1250°C or 1000°C for precision.
• LECOCEL, LECOCEL II, or LECOCEL II HP accelerators.
• Iron chip accelerator.
• NIST SRM 886, LECO 502-318/319/320 ore calibration standards, and synthetic calibration materials.

Main Results and Discussion

Typical results show excellent agreement with certified values and low reproducibility:

• LECO 502-320: 2.61 % C, 2.44 % S (s ≤ 0.02).
• LECO 502-030: 5.01 % C (s = 0.02).
• NIST SRM 886 (gold ore): 5.70 % C (s = 0.05), 1.48 % S (s = 0.01).
• LECO 502-318: 0.169 % C, 0.544 % S (s ≤ 0.005).

The single-point, through-origin calibrations yielded linear response and robust drift correction, demonstrating the method’s reliability for diverse ore matrices.

Benefits and Practical Applications

This technique offers rapid, simultaneous determination of carbon and sulfur with minimal sample preparation, high precision, and straightforward calibration. It supports:

• Mine process optimization and acid consumption control.
• Gold recovery improvement by organic carbon assessment.
• Environmental monitoring of tailings and waste rock.

Future Trends and Opportunities

Advances may include further automation of sample handling, integration with laboratory information management systems, miniaturization, and data analytics for real-time process control. Expanding the methodology to additional elements could enhance comprehensive ore characterization.

Conclusion

The LECO CS744 method provides accurate, precise, and efficient measurement of total carbon and sulfur in metal-bearing ores. Its reliability and versatility make it a valuable tool for metallurgical and environmental applications.

References

• ASTM E1915: Standard Test Method for Carbon and Sulfur in Steel, Iron, and Related Alloys by Infrared Absorption.