The mineralogy of process stream slurries is a key factor in determining the efficiency of a concentrator. Many on-line measurement systems have been developed and deployed in processing plants that measure elemental concentrations in process streams. These systems use techniques such as X-ray fluorescence (XRF) and prompt gamma/neutron activation analysis (Smallbone, 1997; Lim et al, 2005). However real-time measurement of mineralogy has proven to be more challenging. There are a few systems that measure mineralogy either directly (Roach et al, 2013) or indirectly (Kewe et al, 2014) but each has encountered difficulties that have prevented their widespread implementation. X-ray diffraction (XRD) is a method used to investigate the properties of crystalline materials and minerals. XRD has been used in the laboratory since early in the 20th century to perform quantitative mineral phase analysis on samples of unknown composition. Use of this technique has been widely adopted in the mineral processing industry to carry out routine assays of plant samples. The process involves taking a sample from a stream using an appropriate sampling method and transporting it to a laboratory, either on-site or off-site. In the laboratory the sample is further sub-sampled, ground to a very fine particle size (10-50 micron) and pressed into a sample holder before being placed in the XRD diffractometer for measurement. The XRD pattern is then scanned by the instrument over a period of tens of minutes to hours. Subsequent analysis of the diffraction pattern reveals the mineral phase abundances in the sample. It is clear that the traditional laboratory technique requires laborious sampling, preparation and analysis that can take hours or even days to complete. This means that by the time the results are obtained, they are not relevant to the current operating conditions of the plant. The results are, rather, a snapshot of the process stream composition at the time the sample was collected. Therefore, the analysis cannot be used for real-time process control and optimisation, as the plant conditions could have changed significantly since the sample was obtained. A preferable approach would be the ability to monitor the process stream directly and obtain measurement feedback in real-time. This would allow the operating conditions to be adjusted to optimise plant efficiency.
CITATION:ODwyer, J, Tickner, J, Millen, M and Van Haarlem, Y, 2019. On-Stream Mineral Analysis for Process Control and Optimisation, in Proceedings MetPlant 2019, pp 404406 (The Australasian Institute of Mining and Metallurgy: Melbourne).