The Metals Quality Analyzer (MQA™) for GeoSciences
The ASPEX MQATM
is a compact, rugged, cost effective, fully integrated automated scanning electron microscope (SEM) designed for high speed mineral characterization in diverse environments. The ASPEX ExplorerTM
includes a secondary electron detector (SED) and a backscattered electron (BSE) detector for imaging, integrated with a silicon drift detector (SDD) for energy dispersive X-ray spectroscopy (EDX). The system provides both high vacuum and variable pressure modes for characterization of a variety of GeoSciences' sample types. The chamber has a stage that accommodates a choice of removable, interchangeable and customizable sample holders. The built in vibration isolation system and the standard 110V operation allows for operation at diverse locations without modification.
What can it be Used For
How it Works
- General Mineralogical Characterization
Rare phase characterization (Gold, Platinum, Uranium, Silver, Palladium, etc.)
Routine mineralogy investigations
Process refinement monitoring for minerals of interest (Copper mineral distributions)
- Dry Powder and Polished Epoxy Mount Analyses
The ASPEX MQATM
uses a single hardware control configuration for both the SEM and EDS components resulting in faster analysis times. Unlike frame-based systems, the dynamic scan control in the ASPEX MQATM
uses “stage fields” that are further subdivided into “mag fields”. The “mag fields” are individually defined by deflection of the beam. Movement between fields is done electronically as opposed to frame-based systems that mechanically move the stage. Instead of capturing a high resolution image of the frame, the ASPEX moves the beam across the field in an array of fairly coarse steps. A particle is detected when the BSE intensity exceeds the predefined threshold. This particle-sizing sequence initiates a “rotating chord” algorithm to measure the particle. At a 2048 pixel resolution, a series of chords are drawn through the center of the particle at equal angular spacings. Particle size and shape measurements are derived from the chords. To learn more, see our Automated Feature Analysis
After the particle is detected and measured, an energy dispersive X-ray spectrum is acquired in the center of the particle. Once the particle is characterized (size, shape and elemental composition) user-defined rules placed them into a “class”. If needed, the particles can be relocated and further examined by the operator. The MQATM
provides a customizable reporting tool and automatically generates reports of analyses. In addition, a database can used to store all results of analyses for monitoring long term processing trends.
Overall, the MQA for GeoSciences applications offers a unique, cost effective solution to automated mineral characterization and allows various organizations to bring real control to their process control initiatives.
See the MQA in Action
This video represents how the analyzer scans. In this example, the MQA is looking for Silver (Ag) grains in a complex matrix of minerals. The system efficiently and rapidly scans for the bright Ag grains while ignoring all the material that is not the phase of interest. In frame 5, a single Ag grain is located sized and elementally analyzed to identify it as Ag.