Precise determination of iron in iron ore by controlled potential coulometry

Abstract

A coulometric method for the precise determination of total iron in iron ore is described. The procedure is based on controlled potential coulometry, thus limiting the interference encountered in the conventional volumetric method.

The sample is dissolved by fusing with a sodium carbonate-boric acid mixture and extracting the melt in sulphuric acid. After initial reduction with the working electrode controlled at 0.2 V versus a saturated calomel electrode, the iron(II) ions are oxidised to iron(III) at 0.7 V and the amount of electrical charge passed is measured with an electronic integrator.

Replicate determinations of iron in a standard iron ore containing 66% of iron gave a standard deviation of 0.015%.