Crushing & Pulverising
The sample preparation section of the laboratory is arguably the most important part of the laboratory operation. If the sample preparation is not correct the rest of the analysis is wrong. Because of this and the cross contamination they cause, Ultra Trace will not use 'Hammer Mills' or 'Disc Mills'. We advocate the preparation of the whole sample received by a single stage mixing and grinding process. In this process, crushing is generally unnecessary unless sample pieces are over about 25mm in size.
Jaw crushing, splitting and pulverising a sample sub-fraction is available for very large samples.
Ultra Trace uses conventional LM2 and LM5 Ring Mills for pulverising the samples. These mills are time proven and reliable for this stage of the process. By use of various capacity bowls in the LM2 and LM5 mills, we are able to efficiently pulverise samples from a few grams in size to approximately 4 Kilograms. Samples larger than this will either be split to obtain a 4 Kg sample or pulverised in 4 Kg lots and recombined.
Quality control procedures include frequent random checks to ensure that 95% of the sample is pulverised to less than 75µm in size. The results of these random checks can be reported if required.
A barren wash of the bowls using silica sand is routinely carried out before and after processing a client's sample. Ultra Trace will also utilise a barren wash if considered necessary through a job. This is done at no cost. If requested, a barren wash will be done between each and every sample, for a small additional charge.
Non-ferrous sample preparation is available using a Tungsten Carbide Bowl.
Contamination Issues
All sample preparation process will contribute a small level of specific elements from the equipment to the sample. However, by the use of the equipment detailed above, Ultra Trace will significantly reduce contamination over other types of sample preparation equipment. The wearing surfaces of both crushers and pulverisers are made of Low Chrome steel. Consequently traces of Chromium and Iron will be introduced to the sample.
Pulverising bowls manufactured from alternative materials are available to eliminate these contaminants (however they will introduce other contaminants). For example chrome contamination can be eliminated by the use of simple steel crusher plates and chromium free pulveriser bowls. Iron contamination may be eliminated by use of alternate bowls. Please discuss your requirements.