The purpose of coal sampling and preparation is to obtain a test coal sample whose test results can represent the entire batch of sampled coal.

The basic process of sampling and sample preparation is to first collect a considerable amount of coal from many points distributed throughout the batch, namely primary sub samples, and then directly merge or reduce each primary sub sample into a total sample. Finally, this total sample is processed through a series of sampling procedures to produce the required number and type of test coal samples.

The basic requirement for sampling is that all particles of the sampled coal batch may enter the sampling equipment, and each particle has an equal probability of being sampled into the sample.

In order to ensure the precision of the test results of the obtained samples meets the requirements, the following factors should be considered during sampling:

a) The variability of coal;

b) The total number of samples taken from this batch of coal;

c) The number of sub samples in each total sample;

d) The sample mass corresponding to the nominal maximum particle size.

To meet the basic requirements of sampling, it is best to use a mobile coal flow mechanized sampling method; Static coal mechanized sampling method can also be used in unconditional places. But no matter which method or machinery is used, it must be proven through experiments that there is no substantial bias and the precision meets the requirements.