Solid Sampling

Sampling of solids is more difficult than liquids or gases and larger sampling errors may easily arise due to the lack of uniformity of the material. In table 1, a guide is given for the minimum amount of sample that should be taken related to total size of the bulk material. If the uniformity of the bulk is found to be particularly large (a delivery of iron ore) then the sample quantities will require to be increased.

Table 1 Minimum Sample Size Relative to the Bulk Material

Material Bulk Weighttons (long or metric)	Sample Weight(kg)
up to 0.5	2.5
0.5-1.0	4
1.0-2.0	6
2.0-5.0	10
5-10	15
1-–25	25
10-25	40
50–100	60

Powder, Granules or Crystals

Samples of powders granules or crystals are usually taken with a ‘spear’.

Figure 9. The Sampling Spear

The spear is thrust at an angle into the material (the opening underneath) rotated two or three times and then carefully withdrawn with the opening uppermost. The contents are then discharged into the sample container.

Bulk Stocks

Bulk stocks should be flattened and samples taken at numerous places with the spear. Very large stocks should not be sampled in situ, but should be sampled either as they are accumulated or as the material is withdrawn.

Bags and Sacks

The spear should be inserted in a place where the aperture can easily be closed after sampling. Care must be taken to ensure that no fragments of the container contaminate the sample.