polab® APM- Sample preparation for cement laboratory automation

Pressed tablets are the common way to prepare samples for both XRF and XRF analysis in the cement and other industries. In many cases the same pressed tablet can be used for both analysers, thus reducing cost and sample preparation time. Fused beads prepared from flux cannot be used for XRD analyses, and due to preparation time and reagent requirements have a cost of approximately 10 times that of a pressed tablet.

polab® APM - advantages at a glance

  • Combined mill and press in one small unit with a minimum footprint of only 600 x 1230 x 735 mm (23.6 x 48.4 x 28.9 ″; W x H x D)

  • Patented grinding unit for efficient and gentle grinding, and optimized sample preparation for the different requirements of XRF and XRD

  • Excellent reproducibility

  • High sample throughput and integrated ring cleaning device for APMplus

  • Predefined automatic and user-specific sample preparation routines

  • Operator panel for simple and intuitive operation

  • Grinding and pressing functions can be selected in a combined process or as single processes

Operation

For pressed tablet preparation the sample is ground to analytical fineness, typically d90 < 30µm and mixed with a grinding aid and binder combination. The binder also enables good automated cleaning of the equipment, and makes tablets stable under vacuum, as required in XRF systems. After grinding, the sample is pressed into a steel ring. This steel ring is transferred to an XRF or an XRD analyser where the analysis is conducted using best practices. After analysis, the steel ring is returned, cleaned and re-used for a new sample. The steel ring sample is the best compromise for maintaining a high sample load, assuring minimum cost and maintaining reliable analytical quality for process supervision. Since its launch in 2002, the polab® APM has become the standard for preparing XRF and XRD tablets, and hundreds of APMs are in use around the world.

Low-wear grinding vessel

Wear is the most critical issue in grinding tools. Material wear causes a shift in analytical results over time. This generates additional work for recalibration and increased cost for replacing and maintaining worn grinding vessels. thyssenkrupp carried out long-term testing of various tungsten carbide grades to find the grade that is our standard today. Grinding vessels with minimum wear assure good grinding properties and minimum spare part requirements. Today it is difficult to know how many samples can be processed in one grinding vessel, but the number is considerably higher than 40,000 – 50,000 samples without changes in analytical results.

The APMbasic is the solution for small laboratories where a lot of process steps are still started by human intervention. Sample processing starts by pouring materials into APM’s dosing system. The sample preparation procedure is launched via the integrated touch panel (HIM). After automated sample grinding and pressing, the steel ring with the sample can be taken by a laboratory technician for analysis. The complete preparation procedure from introducing the sample to the removal of the sample is automated.

The basis unit for sample preparation consists of the following components:

  • Sample loader for blind and main sample

  • Grinding aid dosing unit

  • Patented grinding unit

  • Tablet press

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The APMplus is the first full-scale laboratory automation system with a footprint of just one square metre. It comes with either a 20-position turntable or an automation interface for automatic sample feeding. After grinding and pressing, automated cleaning procedures prepare the APMplus system for the next sample. The grinding vessel is cleaned by a sophisticated procedure using compressed air and a dedusting system.

For the standalone version, the steel rings with the pressed sample are delivered either to an output chute, an output magazine or to a belt system linked to the analysers. The only human intervention needed is the introduction of the samples and the pressing of the start button.

APMplus for integration is at the core of all larger, fully automated polab® laboratories. Dosing is done by a robot or handling device. The recipes and sample codes are retrieved from the automation control software polab® AQCnet. After sample preparation, the samples are moved to the analyser by a belt system.


The expanded configuration for the automatic processing of samples consists of:

  • polab® APMplus

  • Input magazine with 20 input positions

  • Internal tablet and ring cleaning

  • Internal magazine for steel rings

  • Automatic grinding aid dosing

  • Output chute

  • Optional: output magazine


The expanded configuration for the automatic transport of samples to XRF or XRD analysers consists of:

  • polab® APMplus

  • Input magazine with 20 input positions

  • Internal tablet and ring cleaning

  • Internal magazine for steel rings

  • Automatic grinding aid dosing

  • Tablet conveyor belt for the movement of samples to the XRF and XRD analysers and back into the ring cleaning device


The expanded configuration for the integration into larger automation systems, such as the polab® Linea or polab® AMT consists of:

  • polab® APMplus

  • Internal tablet and ring cleaning

  • Internal magazine for steel rings

  • Automatic grinding aid dosing

  • Tablet conveyor belt for the movement of samples to the sample output or the XRF and XRD analysers, and back for ring cleaning

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