COMBINED STEMMING Russian patent published in 2007 - IPC F42D1/08 

FIELD: drilling and blasting operations in hard rocks, applicable in various branches using blasting operations in hard rock masses.

SUBSTANCE: the combined stemming has a space over an explosive charge or an air gap filled with loose material. The space with the loose material occupies at least three diameters of the borehole height. A metal device is installed over this space, the device is made in the form of a hollow cylinder cut in the axis, with a tapered expansion in the bottom part, consisting at least of three parts of the same size, which from the top are provided with pins inserted for motion in the horizontal plane in the guide bushes fastened on the bearing ring coupled to the mantle ring by a distance tube on the bench surface. And from the bottom a hollow distance cone is inserted in the cylinder, the cone is coupled to a tubular link, having a thread for a nut on the upper end and freely passing through the distance tube, a conductor of initiating pulse is-passed through the tubular link.

EFFECT: enhanced efficiency of blast breaking of rocks due to locking of the detonation products in the loading cavity up to the moment of complete destruction of the environmental rock by the combined stemming.

2 cl, 2 dwg