Determination of Total Iron in Carbon Reduced Iron Ore by Perchloric Acid-Assisted Digestion and Potassium Dichromate Titration

Rapid and accurate determination of total iron content in iron ore is crucial for mineral processing research and improving iron-making efficiency. Iron ore needs to undergo beneficiation treatment before iron-making. Solid reducing agents, such as coal and brown coal, are commonly used in magnetic separation technology. But the high carbon components in iron ore samples are difficult to completely remove during the dissolution process, resulting in cloudy or even dark black solutions. When using SnCl₂, TiCl₃ reduction, and potassium dichromate titration methods to determine total iron in iron ore containing solid reducing agents, it will be impossible to directly determine total iron. Although the traditional method of roasting to remove carbon before analysis can be used to determine the total iron content in iron ore, this method has large errors, an analysis cycle of 2-4 hours, and high energy consumption. This paper proposes a method of removing carbon from the sample by adding perchloric acid drop-wise during the dissolution process of sulfur phosphorus mixed acid, which has achieved good results. Through conditional experiments, the optimal condition for carbon removal was determined to be the drop-wise addition of perchloric acid when sulfuric acid smoke has just left the liquid surface. This method was used to determine samples prepared from iron ore standard samples and bituminous coal standard samples in different proportions, with relative standard deviations (RSD) of 0.07%-0.43%, and relative errors of 0.10%-0.28%. For samples prepared with solid reducing agents of lignite, coke, anthracite, and graphite in a 1∶1 ratio with iron ore standard samples, this method has good decarbonization effects, with RSD of 0.25%-0.33%, and relative errors of 0.04%-0.19%. Using this method and traditional methods to determine actual samples with different carbon contents, The RSD ranges from 0.08%-0.40% and 0.14%-0.68%, respectively. The analysis time for a single sample is 30 minutes and 2-4 hours, respectively for this method and traditional method. Compared with traditional roasting method, this method solves the problem that carbon containing iron ores cannot be directly determined for total iron by titration, eliminating the step of removing carbon from roasted samples. It reduces the error of analysis results and improves work efficiency and reduces energy consumption with its simple operation process.