Blast hole

During preparations for blasting the sulfide mineral copper pyrites, ammonium nitrate-based blasting cartridges exploded prematurely in the blast holes. This was attributed to exothermic interaction of acid ground-water with the sulfide-oxidant combination. 

Up to 5 kg of gunpowder mixture comprising saltpetre (10) charcoal (2) and sulfur (1) is packed into the pine cylinder where a blasting hole (nozzle) is bored at the bottom of the cylinder. 

Si No 2 fuel oil 5.5% requires at least 20% of AN particles to be less than 200 mesh. The min diam of the blast hole for these mixts is approx 20mm. A mixt of AN 60 NaNOg 40% formulated with.6% oil has a 60% increase in expl power. Surface-active agents (0.5%) have possible benefits in increasing expl power. Increased power can be obtd by slurrying with water but stronger fuses are reqd for deton]... 

M-F. Koshamov, Ibid, 1968, (65/22), 92-6 CA 71, 31946h(1969) (Density of the charging of blast holes with Igdanit by means of an ejector pneumatic charger PPZh-2)... 

Diesel oil into the atmosphere during the pneumatic loading of blast holes with Igdanit)... 

Explosives used in blasting operations(such as in quarry work, non-gaseous mines, strip-coal mines, metal mines, ditching, stump blasting, hole drilling or in the demolition of buildings,... 

FIGURE 2.9 SEM micrographs of micromachined holes in borosilicate glass using three different methods, (a) Ultrasonically drilled hole hole diameter, 500 pm. (b) Laser machined hole hole diameter, 300 pm. (c) Sand-blasted hole hole diameter 1000 pm [104], Reprinted with permission from the Institute of Physics Publishing. 

A mat of woven steel wire, rope, scrap tires, or other suitable material or construction to cover blast holes for the purpose of preventing flying rock missiles. 

That part of a drilled blast hole that remains when the force of the explosion does not break the rock completely to the bottom of the hole (-> Large Hole Blasting). 

A charge of explosives in a blast hole in the form of a long continuous unbroken column. 

A method of blasting in which an air space is left between the explosive charge and the stemming, or in which the blast hole is purposely drilled lager than the diameter of the explosive cartridge to be loaded - Contour Blasting. 

The section of detonating cord that extends within the blast hole from the ground surface down to the explosive charge. 

The practice of enlarging the bottom of a blast hole by the use of a relatively small charge of explosive material. Typically used in order that a larger charge of explosive material can be loaded in a subsequent blast in the same borehole. 

The perpendicular distance from blast hole to the free face measured at the floor elevation of the quarry pit. 

Re. Shabecoff s report in the New York Times, who drilled the blast holes, where did the equipment come from, and why are there once again no witnesses to this considerable amount of work Why is no trace of any of this visible on the air photos ... 

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