Ferrosilicon particle size and shape measurement with Dynamic Image Analysis

Ferrosilicon (FeSi) is an alloy of iron and silicon with a very variable silicon content between 10% and 90%. It is used as a so-called master alloy in steel production, which is added in small amounts in order to adjust the properties of the melt, the cooling process and the finished product.

The main advantage of FeSi is its deoxidizing effect (i. e. it reduces metals from their oxides), but it also helps to prevent the loss of carbon. Furthermore, ferrosilicon is used in electrode coatings and in the production of silicon, hydrogen and magnesium.

Ferrosilicon is produced either in a blast furnace or electric arc furnace by the reduction of quartz sand (SiO2) with coke in the presence of iron. The melt is poured out of the furnace and solidifies in the form of a flat sheet.

After cooling, this sheet is crushed by appropriate machinery and then further processed in a crusher. The resulting particle size distribution ranges from fine dust-like particles to cm-sized chunks. The FeSi is sifted into different size grades for further use.

Microtrac's CAMSIZER series is ideally suited for the particle size distribution analysis of ferrosilicon and other granular metals. Microtrac analyzers are used both for quality control industrial applications as well as research purposes. 

Measurement example: Different grades of FeSi

In this example we present the results of the particle size analysis of different grades of ferrosilicon (Fig. 4). All measurements have been made with a CAMSIZER P4 image analyzer. The finest sample is in a size range from 0,2 mm to 0,7 mm. The largest sample contains particles up to 30 mm, which is the upper size limit of the CAMSIZER P4. Repeatability of the results is a key factor to evaluate the reliability of a measurement device. The CAMSIZER P4 can detect and analyze hundreds of thousands or even millions of particles within a few minutes. The size distribution is therefore based on a huge dataset, giving the result a high confidence level and leading to great repeatability (Fig. 5).

Particle characterization with Dynamic Image Analysis offers a wide range of different parameters that can be determined for every particle: different size definitions for length, width and equal area diameter are available, as well as various shape parameters such as aspect ratio, roundness, convexity and many more. If comparability to traditional sieve analyse is required, the size definition “particle width” is used to calculate the distribution. Sieving allows width measurement as well since the particles pass the apertures with the smallest projection surface (Fig. 6). Comparability of CAMSIZER P4 results and sieve analysis can easily be established (Fig. 7).

Summary