Main part of the permissible test of electric detonators for use in coal mine is aimed at safety tests against methane ignition. However, safety properties of electric detonators against coal dust are also important both for safe blasting at coal mines and safe operation in pulverized coal combustion furnaces at power plants and others in case of containing of miss-fired detonators.
Several series of safety tests of electric detonators against methane and coal dust were carried out varying temperatures from room temperature to 150°C. Results are briefly summarized as follows.
1. Spark particles generated from copper-cell detonators is less than those from iron-cell detonators. On the other hands, flame of copper-cell detonators is larger than that of iron-cell detonators and then, it is liable to ignite methane or coal dust in case of copper-cell.
2. When temperature is increased up to 150°C, safety degree of detonators against coal dust decreases considerably.
3. Ignition of coal dust or methane by detonators depends on the flame rather than the spark particles during the initiation of detonators.
