Analysis Of Calcium And Magnesium In Desulfurizers Used For Steel Melts

As the quality of steels has became increasingly demanding， reducing the contentof sulfur、oxygen and other impurities in the steel is the key problem to produce highquality steel production. Adding different desulfurizers can achieve the removal ofimpurities in the steel, so it is important to analysis of the content of active materials ineach desulfurizer to achieve effective control of the steelmaking process and reduce costsand improve the quality of steel.In this thesis, a series of analysis methods were proposed according to the analyticalrequirements of magnesium-based desulfurizer and calcium-iron cored wired proposedby Wuhan Iron and Steel (Group) Company, the main content of this work consist offollowing5parts:(1) The method to detect the total Mg content in magnesium-based desulfurizersamples by EDTA complex titration was established. The standard deviation is less than0.3%and the results showed that the methods are valid with good reproducibility andhigh accuracy.(2) The method to detect metallic Mg content in magnesium-based desulfurizersamples by gas volumetric analysis methods was established. This method has merits ofsimple measurement apparatus, and high accuracy with the standard deviation less than0.3%, it is suitable for the routine analysis of the samples.(3) The method to detect metallic Mg content in magnesium-based desulfurizersamples by Iodine-Ethanol extraction-EDTA complex titration methods was established.The Mg content in high purity metallic magnesium (99.8%) is99.91%by using themethod above mentioned. The results by this method were consistent with the results ofgas volumetric analysis methods.(4) The method to detect total Ca content in calcium-iron cored wired samples by NH4Cl solution-EDTA complex titration methods was established. The method was highaccuracy with the standard deviation less than0.25%.(5) The method to detect metallic Ca content in calcium-iron cored wired samples bygas volumetric method in comparison with high purity magnesium was established. Thelinear correlation equation between the weight of high purity metallic calcium (m0) andthe mass of metallic calcium (m) is m=0.9907m0, R2=0.9997. In this method, the oversizeand undersize of the calcium-iron cored wires sample were treated with5%NH4Cl+0.2M EDTA and2%NH4Cl, respectively. The standard deviation was less than0.25%and can meet the requirement of routine analysis.