ASP100™. Better XRD accuracy with new sample preparation

June 18, 2014 Ian T. Campbell

FLSmidth leads innovative automatic sample preparation. Breakthrough technology enhances XRD results.

Sample preparation is probably the most important procedure determining the quality of X-ray powder diffraction (XRD) data. This assumes, of course, that the sample used is correctly prepared and representative with crystallites of ideal particle size, good homogeneity and random orientation. The new ASP100 achieves better sample preparation than all other techniques and improves the reliability of the XRD results.

An alternative to back loading
Traditionally, samples are prepared by back loading. This is a technique that has become standard practice to reduce the effects of pressure that often result in unfavourable (non-random) distribution of crystallites referred to as preferred orientation. However, as more cement producers depend on accurate XRD analyses, they are finding that the back loading technique does not sufficiently reduce preferred orientation and leads to misinterpretations. To overcome this problem many have turned to transmission type measurements where samples are loaded into glass capillaries. Nevertheless, the trade-off is that samples are often non-representative because they must be small in volume, and this technique is difficult to automate.

The ASP100 provides fully automatic sample preparation with demonstrably reduced preferred orientation in comparison with the standard back loading technique. Also, it reduces maintenance and operational costs and makes a tedious and delicate process routine and easy.

Read the brochure about ASP100 >

 

New patent-protected technology

 “We set out to build a more reliable and better machine with reduced dependencies on consumables and a high-throughput capacity. We did all that, and then we were very pleasantly surprised when we realised how good the results were. Simply put, every test proved positive and after discussing XRD results with the experts, I knew that we really had achieved something special. That’s why we patent protected it,” Ian T. Campbell, CEO FLSmidth Brno, explains.

The FLSmidth Brno (Czech Republic) team designed the automatic soft press (ASP100) with a combination of innovative technologies. In keeping with the principle of soft pressing being “better” (reducing preferred orientation), the team designed an advanced soft pressing mechanism that mimics human hand pressure. This was combined with a top-loading technique and a new textured surface tool to ensure particle randomness.

Test results demonstrate improvements
Two ASP100 units were placed into FLSmidth’s Ore Characterization & Process Mineralogy labs in Salt Lake City, USA, for critical use in a high capacity mineral lab that feeds six XRD instruments. Concurrently, samples were made in Brno and advanced testing was carried out in cooperation with specialists from the Material Research Centre of the Technical University in Brno. The FLSmidth Salt Lake City facility tested and proved the ruggedness of the ASP100 and the low sample-height-displacement error (tolerances).

 

 

 

 

 

 




The hand back loading technique and the ASP100’s fully automated front loading technique were compared by means of Phi measurement. Advanced Phi experiments reveal the degree of preferred orientation. The ideally measured lines, representing different crystallographic planes, would be horizontal (flat). See graphs showing comparison of Phi measurement results on opposite page. Flatter curves are better, meaning less preferred orientation.

The final statement of an expert from the Material Research Centre made it quite clear:
”The results are even better than back loading."

Technical specifications of the ASP100
• No consumables – all sample holders are internally
• 12 pressing recipes with 4 defined pressed conditions
• Buffering capacity of 12 samples
• Throughput = 15 samples per hour
• Advanced textured pressing surfaces available

About the Author

Ian.Tcampbell@flsmidth.com

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