Sample Preparation

Sample Preparation

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 105°C 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 2.0 mm.
  • 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.