BACKGROUND High-frequency infrared carbon and sulfur analyzer can be used to rapidly analyze the sulfur content in different ores with good stability. However, the analysis is greatly affected by the flux type, oxidation temperature and time for various sulfur contents and sample types.

OBJECTIVES To expand the detection range of sulfur and improve the detection efficiency.

METHODS A high-frequency infrared carbon and sulfur analyzer was used to study the influence of experimental conditions on the analysis results. By optimizing the sample weight, the amount of flux, and the analysis time, a method for determination of sulfur with a content of 0.74% to 32.0% in ore samples was established.

RESULTS The optimized conditions were 2.8L/min oxygen flow, 45s analysis time, sample weight of 0.0400g, 0.50g pure iron and 2.0g pure tungsten as flux. The detection limit of the method verified by national standard material was 0.185%, and the limit of quantification was 0.739%. The linear correlation coefficient of calibration curve was better than 0.9995, the relative standard deviations were less than 3% (n=11) and the relative errors were less than 2%. The relative errors were all less than the allowance limit for the ores analysis of relative error obtained in accordance with DZ/T 0130—2006. The actual samples of the laboratory were determined by this method and the traditional iodine combustion method. The absolute error of the measured values between the two methods was less than 0.5%, with an extremely significant linear relationship (R²=0.9995), indicating good agreement between the two methods.

CONCLUSIONS The method has high precision and low relative error. The detection limit, precision and accuracy of the established method meet the analytical requirements of the ores.