Stemming Material

Aggregate or other inert material used to maximize the effect of an explosion, by filling the remainder of holes or between decks of explosives after the holes have been charged with explosives.

The length of the stemming column should be between 20 to 30 blast hole diameters.

For average conditions choose 25 diameters.

For a 200mm diameter hole this would be 5m of stemming.

Where the stemming material is angular material with fines screened out and the bench is solid material at the collar the stemming column may be reduced to 20 diameters.

If the stemming column is reduced much below 20 diameters the likelihood of cratering and rifling increases.

If the stemming column is increase above 30 diameters there is the potential to leave blocky material at the collar.

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