Grinding of Ferro Alloys for Successful Chemical Analysis

Table of Contents

Preparation of Ferro Alloys
About Fritsch


Ferro alloys comprise Iron endowed with Vanadium, Titan, Chrome, Niobium, Silicon or Manganese, only to name some of the most common (Fig. 1). These alloys contain as well additional elements. In certain applications, determining the precise composition of the alloys is necessary. For ferro alloys, the wet-chemical pulping is the only possible investigation technique (if the material is available in a powder form).

Figure 1. Ferro Alloys samples.

Preparation of Ferro Alloys

The following is an example of a ferro alloy composition analysis performed by acid hydrolysis on a sample prepared using the Fritsch Jaw Crusher PULVERISETTE 1, model II and the Fritsch Vibrating Cup Mill PULVERISETTE 9.  

Figure 2. Ferro Alloy Samples after initial processing in the Jaw Crusher PULVERISETTE 1, model II.

The first step requires an initial preparation of the ferro alloy with the Jaw Crusher PULVERISETTE 1, model II, equipped with hardmetal tungsten carbide crushing jaws (Figs. 2 and 3). The ferro alloy is crushed down to the best possible fineness. The sample is then slowly added into the jaw crusher. (Note: Ferrochromium needs to be considered as a borderline application and can only be processed with a higher carbon content).

Figure 3. As received ferro alloy sample (left), after initial processing in the Jaw Crusher PULVERISETTE 1, model II (middle) and after crushing in the Vibrating Cup Mill PULVERISETTE 9 (right).

The maximum process time is 2 minutes. The particles size of the evolving powder is mostly below 0.2 mm.

Secondly, the material obtained from the jaw crusher needs to be crushed more finely. The Laboratory Vibrating Cup Mill can be employed for such task (Fig. 3). Fritsch recommends the use of the Vibrating Cup Mill PULVERISETTE 9 incorporated with a hardmetal tungsten carbide grinding set. When extreme materials are used the fine share is sieved off and comminuted again. The fineness obtained using this procedure is excellent considering the running time of the vibrating cup mill and the use of the grinding set.

Thirdly, the acid hydrolysis is performed, for which the fineness obtained with the previous steps is sufficient. Various acid mixtures can be used, they are generally specific for each material. With suitable measurement methods like the ICP or the AAS, the alloy components can be finally determined.

About Fritsch

Fritsch is one of the internationally leading manufacturers of application-oriented laboratory instruments for sample preparation and particle sizing.

The range of instruments supplied by Fritsch includes:

  • Mills for crushing, micro-milling, mixing, homogenising of hard-brittle, fibrous, elastic and/or soft materials dry or in suspension.
  • Instruments for particle size determination by laser diffraction, dynamic light scattering and sieving.
  • Laboratory Instruments for representative dividing of dry and wet samples, controlled sample feeding and ultrasonic cleaning.

This information has been sourced, reviewed and adapted from materials provided by Fritsch.

For more information on this source, please visit Fritsch.

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