Three areas that may affect the quality of your mineralogy data

The complex nature of QEMSCAN mineralogy results necessitates a thorough assessment of data quality relative to ‘best practices’ values. The MinAssist data validation service makes use of additional data that you can request from your commercial service provider or, if available, are assessable within the QEMSCAN datastores. We interrogate these data to provide an assessment of the three main aspects affecting you the quality of your mineralogy results:

Sample preparation,

Measurement setup, and

Reconciliation between assay and mineralogy results.

Sample preparation and measurement setup are critical steps that can introduce errors into a QEMSCAN analytical program. Associated errors can be identified through careful investigation of the relevant data.

• Variations in mineralogy between replicate sample blocks

Depending on the project scope two or more replicate blocks are prepared and analyzed for each sample or its size fractions. The data from the replicate blocks are accumulated to arrive at more robust average values for the final mineralogy result. Large variations between the results from individual replicate blocks suggest sample preparation errors.

• Particle packing density

The Packing Density is a measure of the area of the block surface that contains particles relative to the amount of background epoxy. If the sample has not been prepared correctly, then the Packing Density will be either very high or very low. When this occurs one needs to consider why there is deviation from the required packing density before the data is used for further interpretation.

• Large areas of the sample holder accidentally analyzed

Incorrect positioning of the samples in the instrument can lead to large amounts of the sample holder being measured in addition to the sample block. It is common for a small portion of the sample holder to be analyzed, however, large amounts can impact negatively on the overall mineralogy results.

The most common way to assess the quality of QEMSCAN mineralogy results is by means of the measured to mineralogy-computed chemical assay reconciliation, which gives an indication of the accuracy of the mineralogy results, assuming, amongst other things, that the measured assay data are considered to be the correct results. Because the mineralogy-computed assay data rely on properties such as mineral composition and density it is important to carefully assess the SIP and mineral lists to ensure reasonable and objective assay reconciliations.

MinAssist has established a data validation procedure based on information automatically collected during sample measurement to assess the quality of sample preparation, measurement setup, and the accuracy of mineralogy results. These data are used to provide an overall measure of the data quality for each sample. Please contact our expert consultants Melissa or Pieter if you use QEMSCAN mineralogy results regularly and have datasets that you would like to validate. Our services will help you build confidence in the quality of your mineralogy results.