Laboratory tests

Sampling techniques

NONE of the following tests are valid unless a representative sample is provided. In very unusual circumstances it may not be possible to provide other than a grab sample. It may appear to be better to obtain some information rather than none. However, experience shows that the quality of the information obtained can be so misleading that it may be better not to sample at all!

It is important that the personnel performing the sampling are trained and understand the effects of incorrect techniques. This aspect should be specifically included in the relevant Corporate Quality Manual for the site.

1.1 Moist Silica Sand

The recommended procedure is to take a minimum of three samples. At the point to be sampled use a scoop to remove the surface material to a depth of at least 150 mm (6") to expose the sand underneath and avoid surface contamination.

Using the scoop obtain at least 300g weight for each sample or prepare a composite sample of equal proportions of the sand. Repeat until three samples or the equivalent composite sample have been taken, at points evenly distributed over the stockpile.

Whatever type of sample is obtained, thoroughly mix by cone and quartering to reduce the sample weight for analysis. See Section 2.1.

1.2 Dry Silica Sand

Extra care must be taken when sampling to avoid particle segregation. Where practical it is advisable to obtain the samples from a dry sand feeder, conveyor or sand flow during loading, either incrementally using a cup sized article until the required sample weight is obtained, (note - Health & Safety Requirements in respect of dust generation must be observed at all times) or from an automatic sampling system.

1.2.1 Tankers

...must be sampled to obtain sufficient from each filling hatch on completion of loading. The combined sample weight should be approximately 1500g. The minimum weight should be one kilogram.(Note-it is not acceptable to sample bulk tanker deliveries from the rear discharge outlet.)

1.2.2 Tippers

...samples to be taken during loading at the feed input point to give a combined weight of approximately 1500g . The minimum weight should be one kilogram.

1.2.3 Stockpiles

...sample a dry sand stockpile in the same way as moist sand, except that the sand must be sampled from a depth of not less than 0.5m (18") below the surface to avoid the effects of segregation.

The samples are combined before being reduced in weight by passing through a riffle box.
See Section 2.2

1.3 Naturally Bonded Sand

The procedures are the same as: Moist Slllca Sand Ref. Section 2.1

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