Sulfur and Carbon Determination in Cement, Clay, Fly Ash, Limestone, Soil, and Ore

Significance of the Topic

Accurate determination of carbon and sulfur in cement, raw materials and environmental matrices is critical for quality control, process optimization and regulatory compliance. In cement production, carbon influences kiln operation and material properties, while sulfur content affects corrosion, setting behavior and emissions. In soils and ores, carbon and sulfur analyses inform agronomic assessments, metallurgical kinetics and environmental monitoring of waste streams.

Objectives and Study Overview

This application note evaluates the performance of the LECO SC832 series instruments (SC832, SC832DR, SC832HT) for simultaneous carbon and sulfur analysis across five sample classes: cement, fly ash, limestone, soil and metal-bearing ore. The study aims to demonstrate precision, accuracy, ease of use and cost-per-analysis considerations for each model configuration.

Methodology and Instrumentation

Samples were ground to <150 µm, dried at 105 °C and weighed (0.10–0.25 g). Combustion at 1450 °C (SC832/DR) or 1550 °C (SC832HT) in an oxygen stream converts C and S to CO2 and SO2, detected by infrared cells. Key method parameters include:

• Furnace temperature: 1450 °C (SC832/DR), 1550 °C (SC832HT)
• COM-CAT accelerator: required for 1450 °C operation
• Dual IR cells: in SC832DR and SC832HT for improved sulfur range
• Integration times: 60–360 s for carbon, 120–360 s for sulfur
• Auto-detect baseline and comparator usage

Used Instrumentation

• LECO SC832 Series analyzers (SC832, SC832DR, SC832HT)
• 528-203 Ceramic Boats
• 502-321 COM-CAT combustion accelerator
• LECO or NIST reference materials

Key Results and Discussion

Across all sample types, results showed excellent repeatability (relative standard deviations typically below 1 % for carbon and 0.5 % for sulfur). The SC832HT model, operating at 1550 °C without COM-CAT, achieved comparable precision with simplified preparation and lower consumable costs. Typical recoveries matched certified values for NIST SRMs in cement (0.83 % S), fly ash (0.15 % S), soil (0.14–0.32 % S) and ore (1.06–2.44 % S). Dual range sulfur detection extended linearity from trace to percent levels, while carbon results remained stable across models.

Benefits and Practical Applications

• High throughput analysis for production and QA/QC laboratories
• Reliable detection of low-level sulfur in cement and soils
• Cost savings through elimination of combustion accelerator (SC832HT)
• Versatility across a wide range of matrices
• Automated baseline correction and range selection improve ease of use

Future Trends and Applications

Advancements in IR detection and furnace design may further enhance sensitivity and reduce cycle times. Integration with laboratory information management systems and remote diagnostics can streamline workflows. Emerging needs include offline monitoring of greenhouse gas precursors in soils and rapid screening of recycled-material feedstocks for sustainable cement production.

Conclusion

The LECO SC832 series provides robust, precise carbon and sulfur analysis for diverse materials. Model selection balances temperature capability, consumable requirements and cost per analysis. These instruments support quality assurance in cement manufacturing, environmental soil testing and ore characterization, delivering reliable data for process control and compliance.