| Summary: | Mining operations often send samples for testing to commercial laboratories. Unless a customised test is requested, they expect laboratories to use standard procedures, which are reproducible. A thermal coal and a metallurgical coal were sent to eight laboratories, which were requested to perform a basic flotation test (AS 4156.2.1-2004) and a sequential flotation procedure test, i.e., standard tree test (AS 4156.2.2-1998). This study compared the reports produced by the various laboratories and compared them with the requirements laid out by the Australian standards. It was found that many elements were missing in most cases, probably due to the fact that some of the requirements of the standard, such as size analysis, are offered as other services. The basic tests generally agreed with one another whilst the sequential tests presented more variations. A quantitative analysis of the variation in the yield–ash curves produced by the sequential procedure was conducted using dynamic time warping (DTW). This approach can be used to numerically compare yield–ash curves and perform statistical comparisons.
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