Explosive charge assembly for directed blasting under high temperature conditions, such as tapping of blast furnaces

摘要

658,625. Blasting devices. DU PONT DE NEMOURS & CO., E. I. Oct. 4, 1948, No. 25867. Convention date, Jan. 29. [Class 9 (i)] [Also in Group XII] An explosive device more especially adapted for tapping blast furnaces comprises a metal container 1, housing at one end an explosive charge 3 with a conical recess fitted with a rigid liner 4. The charge may be a 95-5 blend of cyclotrimethylenetrinitramine and high melting point wax, e.g., paraffin or Montan, pressed to a density of 1.6 gms. per c.c. in a thermosetting plastic casing 5. A packing 6 of asbestos or similar heatinsulating material holds the container 5 in postion. A booster charge 7, e.g., low density cyclonite is placed at the end of the charge in contact with an electric blasting cap 8, the cap being also surrounded by insulating material. The unoccupied part of the container forms a " standoff " for the charge which may be 2 to 5 times the diameter of the charge. The container 1 has removable end closures 2, 10. The electric blasting cap (Fig. 2) has a gilding-metal shell 13 containing a pressed charge 14 of cyclonite on which is superposed a primer charge 15 and an igniting composition 19 in which is embedded a bridge-wire connecting leg-wires 17 extending through a rubber plug 16. Alternative compositions for the main charge 3 are pentaerythritotetranitrate, ethylenedinitramine, cyclonite or mixtures of these with trinitrotoluene. The liner 4 may be of aluminium, copper, glass or steel and the preferred cone angle is 60 degrees. In tapping furnaces, a hole is first drilled through the clay plug at the base of the furnace and the device inserted in the hole. When the forward closure 10 contacts the iron shell of the furnace the device is fired. Specification 610,106 is referred to.