Hand Held Sensor for Real Time Measurement of Fluorine Mineral Contamination in Coal

The project's objective was to create a new type of hand-held sensor for real time measurement of fluorine (mineral) contamination in coal. The minerals targeted are the two dominant non-clay fluorine minerals, fluorite and fluorapatite; fluorine hosted in clay minerals was not considered a target as this is readily removed from the coal product by washing.

The goal of the project was to develop a “Novel Fluorescence” (NF) based technique to measure fluorine concentration from fluorapatite down to 100 ppm concentration, and down to a grain size of 30 μm diameter, which was achieved by a test handheld prototype device. The prototype consists of a light-source (excitation module) integrated to a detector (emission module); our previous work has determined the excitation (594 nm) and emission wavelengths (1100 -1200 nm) required for this sensor. Current design considers minimum field-of-view for reasonable sampling error, and excitation power requirements for rapid measurement.

Results inform the later-stage prototype construction and signal processing improvements detailed in this final report, and are the information required to build a TRL 6 pre-production device for field testing and validation.

The test handheld prototype device enables fluorescence from fluorine-bearing apatite naturally occurring in coal core to be readily detected and visualised in near real time. Emission was also seen from crushed coal naturally bearing some fluorapatite. These results demonstrate that the device is suitable for further development and is anticipated to effectively address two major industry use-cases: core scanning and subsample analysis.