Coal is made up of plants buried under the soil and gradually decomposed, compressed under high pressure, high temperatures for millions of years. The longer the formation time, the older the coal and the higher the carbon content in the coal. The coal deposits are most abundant in the Northern Hemisphere: China, Russia, European countries, Canada, USA .... In Vietnam the largest coal mine in Vietnam in Quang Ninh, Coal production in the world average 5 billion tons per year In coal mining there may be fires due to the presence of combustible gases such as CH4 (methane) generated in the coal furnace. We can not smell the smell so we do not use candles, oil lamps when down the mine with a flashlight, electric lights are separated by electricity in and out of the lamp. Be careful with explosives placed in the furnace, coal mining must ensure safety in the mine.