The experience of iron determination in technogenic materials with a high copper content by the redox titration method: case study of the waelz slag

Redox titration is one of the most common classical methods widely used in practice for the determination of total iron. A well-known procedure ISO 2597-1 (GOST 32517) includes the decomposition of a sample with dissolution, the reduction of Fe3+ to Fe2+ using a SnCl2 solution and its titration with a K2Cr2O7 solution in the presence of sodium or barium diphenylaminosulfonate as an indicator. We propose to use potassium tetrahydroborate KBH4 as a reducing agent for Fe3+ to Fe2+ instead of SnCl2 to modify a titrimetric method of total iron determination. The features of the well-known and considered methods are studied when using sintering for sample decomposition during the analysis of a large number of samples. Application of the developed method for the analysis of standard samples and technogenic materials with a high copper content, namely, Waelz slag showed a satisfactory accuracy and reproducibility of the obtained values of the total iron content. The results obtained indicate the possibility of the application of this method to the iron determination in the samples with a high copper content without an additional step of the iron separation from copper. A high productivity of the analysis (apart from the absence of the separation stage) is achieved due to the simplicity of the reduction process occurred at room temperature, no need for the control of the added amount of the reducing agent, and the possibility of holding the solutions for a long time before the titration. These advantages along with the no need for using toxic mercury compounds during the analysis make the method attractive for the analysis of a large number of samples.

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