FIELD: mining.SUBSTANCE: invention relates to mining and can be used to determine the ejection hazard of coal seams in underground mining. In the mining conditions, coal samples are taken in a hole drilled from a preparatory development with a diameter of 43 mm, from a depth of 3.5÷5.5 m with a core picker that is mechanically connected to a borax made of twisted steel, and placed in a sealed steel beaker having an external manometer for measuring the gas pressure in the cover, a resistance in the inner region with the contacts removed for temperature measurement and a steel rod for breaking the coal sample during rotation. After that, within 1.5÷2 hours a glass with a sample of coal is delivered to the laboratory and the gas pressure in the glass is determined by the manometer. Further, the sample of coal in the beaker is destroyed for 1 minute and the final temperature, the increment of the gas pressure are fixed and the weighted average radius of the coal particles is determined. Coal sample is successiv
