Analytical Sample Preparation is one of the most important steps in the analytical testing process. The goal is to achieve a homogenous sample or a sub-sample that is representative of the submitted material. If this is not achieved, then the analytical result can be biased or even meaningless! Set Point Laboratories uses hi-tech crushing and milling equipment, with the sample preparation procedures accredited as separate entities on their own – apart from sample analysis itself.
• Samples are checked and sorted according to client’s submission sheet
• Every batch of samples has an information sheet
• Samples are inspected for any trace of moisture, if they require drying we place them in the drying oven at temperatures until they are dry
• Each sample is weighed on the top pan balance and its weight is recorded in the LIMS system
• Primary: We crush the rocks, rock chips or lumps using a jaw crusher and place the crushed material into a clean and labelled plastic bag
• Secondary: We then crush the resulting chips to a fineness of 90% less than 2.0mm
• If the sample requires splitting, we split it using a Jones riffle splitter, the split is placed into a new sample bag and the remaining sample (coarse reject) will be returned to the client.
• The sample is milled to achieve a fineness of 90% less than 106µm or 80% passing 75µm
• After milling, the contents of the bowl are emptied onto a brown paper sheet and transferred into the sample bag.
• Once a batch of samples is completed, they are repacked for analysis.
Laboratory Quality Control
• One out of every 10 samples passing through the secondary crusher is screened at 2.0mm to check that 90% of the material passes
• One out of 10 samples of every batch is screened at 75µm or 106µm, whichever is applicable , to check that percentage of the material passes
• Percentage loss for samples screened should be <2%
• Clean bowls , discs and lids with cleaning running water and compressed air between each