Hazen Research reports on how QEMSCAN^®-based multiple element X-ray mapping is a new and power tool that allows them to distinguish separate phases, and to illustrate complex textures, in a very short time. 

Dr Hanna Horsch, Manager, Quantitative Mineralogy, Hazen Research Inc 
www.hazenresearch.com

Background

At Hazen, we perform industrial research and development for clients in the mineral, chemical, energy, and environmental fields. Projects range from bench-scale experiments and analyses to multi-million dollar continuous pilot and demonstration plant testing. In the Mineralogy Department, we are faced with different and complex, often low-grade, ores of diverse commodities, almost on a daily basis. Fast turnaround in providing answers to key questions posed by process engineers (such as liberation sizes, deportment of elements between different minerals, mineral association, and recovery potential) is essential. Initially, general information and visual representations of features that may influence the mineral processing design is critical. However, a full report, with supporting quantification of the mineralogy needs to follow, but this can often be time-consuming. Here is where elemental X-ray mapping becomes a vital tool for our business. 

Methodology

QEMSCAN iExplorer™-based X-ray mapping was first introduced to the Automated Mineralogy community at the 2011 North American Users Group meeting in Portland, and became available with the Beta release of iExplorer version 5.2. Since 2009, Hazen has been involved in beta-testing of new FEI software releases, such that we have versions 4.3, 5.0, and 5.2 installed side-by- side. Any new project is analyzed using v5.2 as we always want to make use of new and improved software functionalities, but if required, we can also revert to older versions. 

At Hazen, we acquire the data using the new Spectral Analysis Engine (introduced with the release of v5.0). The spectral data are acquired in a two-tier format, with the old peak intensities of about 30 elements being stored side-by-side with the newly enabled 72 elements. The concentration of elements is utilized in the X-ray mapping, which we do after data acquisition is complete. A SIP that was generated using v4.3 or older can be utilized - this means that X-ray mapping can be done without the need to develop a new Mineral SIP in v5.2. 

Before processing the dataset as X-ray maps, we copy the Datastore, and a new SIP is generated in the Datastore explorer, together with a Primary List. The SIP contains only Background and Other at this stage. Elemental SIP entries are then generated in the SIP Editor–Debugger.  

Results

We illustrate the types of output from this new application with data collected on a sample from the Schwarzwalder Mine, in Ralston Buttes district, Jefferson County, Colorado, USA. The sample analyzed contains complex fractures and hydrothermal veins which cross-cut Precambrian basement rock. Uranium is known to occur within these structures, and the aim of the study was to map the distribution of uranium.

Figure 1 shows the results of mapping for uranium only (this was how FEI originally envisaged the application would be used - mapping of single elements). Figure 2 is an example of a multiple element map (of the same area as that in Figure 1) that was generated within 1 hour after data acquisition was completed.

The power of these images is that both elemental concentration and distribution can be easily and quickly visualized.