A comparison of Fe(III) to Fe(II) reduction methods in iron analysis via titration

Reduction of Fe(III) to Fe(II) is one of the most important steps in the titration process to determine the total iron content in a mineral sample. This step of titration is often conducted in different ways. Using tin chloride-mercury chloride, small pieces of pure aluminum and tin chloride-titanium chloride are among these methods. To check the accuracy of the methods, a standard sample was used, and the analysis of the samples showed that all three methods were within the acceptable error range. To evaluate the precision of the methods, different iron ore samples were used and statistical analysis was conducted after multiple analyses. Based on mineralogical studies, a variety of iron-containing minerals were observed in the samples, but the main minerals were found as hematite and magnetite. The statistical results showed that, on average, the analysis variance of all samples in method SnCl2-TiCl3 was higher than other methods. Also, the average coefficient of variation was different according to the type of method and sample, so the lowest and highest were 0.32 and 2.66, respectively, but for all samples, the Al method was lower than other methods and equal to 0.76. Also, in terms of environmental and safety issues, the Al method is more suitable than the SnCl2-HgCl2 and SnCl2-TiCl3 methods due to the absence of mercury and perchloric acid.