Pelletizing presses

HERZOG offers an extensive product range for this type of sample preparation - from manual machines to fully automatic laboratory automations


HERZOG expertise in pelletizing presses

The grinding and pressing of sample material for X-ray fluorescence analysis and X-ray diffraction is a firmly established procedure in many branches of industry and not only in primary raw material production. HERZOG supplies an extensive product range for this type of sample preparation, extending from manual machines to fully automatic laboratory automations. The degree of automation often depends on the amount of samples and the complexity of the sample preparation.


Types of pelletizing presses

Grinding and pelletizing of sample material for XRF and XRD spectroscopy is an established procedure not only within the primary extractive industry but many industrial processes. HERZOG offers a wide range of different equipment from manual machines to fully automatic laboratory solutions.
For sample pelletizing HERZOG provides manual and automatic machines. For manual applications with small or medium sample loads following models are available: TP20, TP20E, TP40, TP 40/2d, TP60, TP60/2d, HTP40, HTP60. All standard pelletizing procedures can be completed using manual pellet presses. The sample material is filled in manually. Dependending on the used model the pressure is generated manually or by an electrical hydraulic unit.
The automatic pellet presses HP-MP, HP-P, HP-PA, HP-PD6 are automatically dosing the ground material into the press tool. After pressing excess material and dust is removed from the steel ring. In the HP-P a second press tool can be used as option to avoid cross contamination between two divergent material types.  The ready pellet can be automatically transported to the analyzer. Following analysis the ring is automatically cleaned and stored in a ring magazine.
The HP- PD6 is a special pellet press for pelletizing of samples for diffractometry analysis. Few grams of sample material is pelletized into a ring using very low pressure. For stabilizing the material within the ring an aluminium button is inserted using a special backloading procedure.

Pressing methods


Depending on the analytical requirements, it is possible to choose between four standard pressing methods:

  • Free pressing
  • Two-component pressing
  • Pressing in an aluminium tray
  • Pressing in steel rings

In automatic presses, the sample material can only be pressed in steel rings because all other pressing methods are too complex and provide insufficient stability when handling samples. For free pressing, pressing of 2 components and pressing in aluminium trays, it is possible to freely select the diameter of the pressing tool with certain provisos.

Free pressing
Free pressing is the lowest-cost pressing method because no consumables are required. Precise dosing of the sample material is also not required.

2-component pressing
Pressing of 2 components requires an additional work step, but also offers the possibility of preparing small sample quantities for analysis. The refill magazine (e.g. boric acid, Boreox) is dosed and pre-pressed in an initial work step. A special pressing tool cover is used for this. The actual sample material is then pressed into the prepared matrix in a second pressing step.

Pressing in aluminium cups

For pressing in aluminium cups, the plunger should have a suitable venting groove in order to prevent compression of gases in the plunger. Aluminium cups are available in various diameters. Aluminium cups have the advantage that no significant costs are incurred if the samples are to be archived. Nevertheless, aluminium cups offer no guarantee with regard to eruptions occurring on the edges.

Cleaning steel rings

Pressing in steel rings
Using steel rings offers far-reaching advantages over the other pressing methods with regard to use in automated sample preparation systems. Using steel rings reduces the risk of contamination in the spectrometer by preventing eruptions on the sample edge. However, high costs are incurred if the re-useable rings must be archived.
Two rings types are available for pressing in steel rings (Ø 40 mm & Ø 51 mm).

Cleaning steel rings
A three-stage brush system can be used to clean used steel rings after the analysis. This can be used with both manual and automatic presses. On manual presses, it is placed manually into the ring and is then removed manually. In automated pressing, the cleaning runs entirely without the operator's intervention. The empty rings are then automatically stored in the internal magazine.