The measurement of porosity for an individual taconite pellet

The knowledge of the variability in the properties of individual taconite pellets as a function of processing conditions may lead to the improvement of the production of iron. An important property is porosity. Pellets with high porosity are desirable for the reduction to iron in the blast furnace. There is a published work describing the measurement of porosity on collections of pellets. Here I describe a method for the determination of the porosity of an individual pellet.Recent determinations of porosity have used the measurements of the skeletal volume and the envelope volume. Helium pycnometry is the method of choice for the measurement of the skeletal volume, whereas volumetric displacement of dry material is now the preferred method for the envelope volume, requiring collections of pellets. I have adapted a method of silhouettes, developed for single items of fruit, to measure the envelope volume of a single pellet. The porosities of six individual sintered pellets from a facility in North-Eastern Minnesota, USA, range from 33 to 38% with a relative uncertainty of about 1%. Certain pellets have significantly different porosities from each other. The magnitudes are comparable to published porosities on green pellets, ranging from 30 to 36%, and to fired pellets, ranging from 28-38%.