Sampling theory and practice

Sampling's A, B C's
Page 3

Sampling is defined as taking a small portion of a whole mass that accurately represents the whole mass.

A crusher or crushers are used to reduce the primary sample, to a pre-determined particle size, then a secondary sample cutter (such as a vezin type sampler) is used to reduce the volume of the primary sample. This process is repeated until a usable size is obtained to send to the analytical lab or assay lab. Quite often, a primary sample of a ton is reduced to 50 pounds for transport to the lab for analysis.

In the lab, this process is further carried out, sometimes pulverizing the particles to 45 - 50 microns in size prior to splitting for elemental analysis or assay. The Final size to be analyzed can range from a gram to 30 grams, typically, and if the sampling process is good, that 1 gram sample will be representative not only of the 1 ton primary sample, but the 1000 tons or 10,000 tons of ore was taken from. It does not require much imagination to see the room for errors in a process where a single gram represents 10,000 tons of material. In actuality, many single 1 gram or 30 gram samples are generally analyzed or assayed to give a representation of 10,000 tons, though, due to the greatly differing characteristics of the ore.

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