Modern SEM-based mineral liberation analysis

Modern digital mine planning, plant design and mineral processing operations demand detailed characterisation of the ore and plant feed. Textural parameters, such as mineral liberation size and mineral association, combine with modal mineralogy data to strongly influence mineral processing conditions and recovery. Traditionally, the measurement of these ore characteristics employed the tools of an optical microscope and/or a semi-automated SEM. These methods are time consuming, costly and frequently produce semi-quantitative results from data sets that are too small to be statistically valid. Thus, the results cannot be used reliably and effectively in digital mine planning and design. In the last 10 years, modern SEM-based quantitative mineralogy tools have advanced rapidly with increasing computer power, improved SEM hardware and the development of sophisticated image analysis methods. Texture resolutions can now be submicron and SEM measurement times have reduced to less than an hour for simple analyses, where previously they required many hours. Through image analysis, particle sections are recognised and separated, and the mineral grains within are delineated for discrete X-ray analysis to determine mineralogy. The modern tools not only increase the speed and accuracy of liberation analysis, but also enhance measurement automation. Automated standard collection assists with the setup of new ore types for routine analysis and automated elemental quantification of target minerals enables the tracking of variations in the composition of the minerals of interest. The key to success for any modern SEM-based mineral liberation analysis system is the close integration of BSE image and EDS X-ray analyses.Integration of the SEM-based quantitative mineral liberation analysis with optical microscope, dual beam systems and X-ray tomography will further enrich the analysis results and the derived user experience.