The main analyses methods used in the lab are X-ray fluorescence and wet-lab titration.
A known mass of the sample is mixed with a flux and heated in a platinum crucible to 1030°C for 8 minutes, agitated and then heated for a further 5 minutes. The contents of the crucible are then poured into a preheated mould.
This is allowed to cool. The ceramic disc that results is then loaded into the XRF machine, which is programmed to analyse the sample for 11 elements found in their oxide form and reads out a percentage composition.
Two elements present in the lime are of concern to end-users such as the steel-making industry. High silicon content can cause wear and tear problems in the steel-making process due to the abrasiveness of silica. Sulfur can cause brittleness of the final steel product, so it needs to be very low in the lime used.
Samples from the kiln are also analysed for incomplete conversion to calcium oxide or loss on ignition.
McDonald’s Lime Limited
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