Geochemical services: Sample preparation

Sample preparation is one of the core competencies of CRS Laboratories Oy. Sample pre-treatment forms the basis for reliable analysis results. In the preparation phase, the volume and particle size of the sample are reduced for a more even distribution of the examined elements.

By means of appropriate preparation methods, high quality equipment and skilled staff, we process a large-sized field sample into a representative subsample according to the needs of our client and the specific sample type.

We also offer other methods of sample preparation and analysis (such as the determination of density, moisture content and element concentration) as well as a pick-up service for sample pallets.

Receipt of samples

We carefully check and sort the samples in accordance with the requirements and record them in our data management system.

Drying

Prior to crushing and pulverising, the samples are dried to remove the moisture. The duration and temperature of the drying are adjusted according to the particular sample type as well as its size and moisture content. A typical drying temperature is +60 degrees Celsius. After drying, the samples are weighed to determine their dry weight.

Crushing

The particle size of the samples is reduced by crushing them before division and pulverising. The samples are crushed to a granular size. The quality of the crushing is regularly monitored through screening tests in accordance with our quality assurance policy. The crushers are cleaned with compressed air between samples, and with olivine diabase rocks and a vacuum cleaner between sample batches.

Particle size > 80% < 2mm
Division with a Rotary Sample Divider (RSD)
Crushing with Rocklabs Boyd Crusher & RSD

Division

The crushed sample often needs to be divided in order to reduce its size for the pulverising. The fine-crushed sample (nominal particle size of < 2 mm) is representatively divided using a Riffle Splitter or a Rotary Sample Divider.

Performed to crushed material of < 2 mm
Riffle Splitter
Rotary Sample Divider

Pulverising

The sample is pulverised to a fine, homogenous powder to obtain a representative sample for the laboratory. The samples are typically pulverised to a particle size of > 85 % < 75 µm. The quality of the pulverising is regularly monitored through screening tests in accordance with our quality assurance policy. To minimise contamination caused by previous samples, the pulveriser container is cleaned after each sample using cleaning sand (feldspar), a vacuum cleaner and compressed air.

Complete pulverising (< 3,5 kg) or partial pulverising (100 g – 1 kg)
Grain size > 85 % < 75 µm
Cleaning sand between samples
ESSA LM5 and LM2 Pulverising Mills

Sieving

The sieving of samples is a part of our preparation services.

The fine fractions of soil samples are typically sieved to < 180 µm or < 63 µm.
The particle size distribution can be determined according to the client’s needs using a sieve pack and a shaker

Further Methods

We also have the capacity to perform density determinations, compress powders, grind plant and peat samples in a cutting mill and incinerate samples in an incinerator, among other operations.

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