Explosive compositions

Abstract

A pumpable watergel explosive composition comprises 10 to 40 wt %, based on the total weight of the pumpable explosive composition, of a continuous liquid phase comprising a solvent, a solubilized chemical sensitizer and a gelling agent and 60 to 90 wt %, based on the total weight of the pumpable explosive composition, of a discontinuous solid phase comprising particulate oxidizer salt particles having interstitial spaces between the salt particles. The watergel explosive composition has a density of 1.05-1.4 g / cc and, a shear thinning rheology such that, when subjected to an external force, the explosive composition has a viscosity sufficiently low to render the watergel explosive composition pumpable. The combination of density and low water content provides energy numbers normally associated with more expensive aluminized formulations.

Description

FIELD OF THE INVENTION [0001] This invention relates to explosive compositions utilizing a continuous liquid phase and a discontinuous solid phase. In particular, the invention relates to ammonium nitrate fuel oil (ANFO) or ammonium nitrate (AN) / watergel blend explosive compositions. In another aspect, this invention also relates to different methods to manufacture the explosive composition. BACKGROUND OF THE INVENTION [0002] Various different forms of explosive compositions are known including ANFO explosive compositions, watergel, explosive compositions, slurry-type explosive compositions and emulsion explosive compositions. Each type of explosive compositions has its own advantages and disadvantages. For example, ANFO explosive compositions are useful in applications not requiring a water resistant explosive formulation, due to its low cost. [0003] Watergel blasting explosives may be selected when a combination of water resistance and superior heave is required. [0004] Slurry-typ...

AI Technical Summary

Benefits of technology

[0021] The solid phase preferably comprises a substantial portion of ammonium nitrate and, may consist essentially of ammonium nitrate particles. Ammonium nitrate is generally one of the lower cost ingredients used in explosive compositions. Accordingly, the use of substantial quantities of ammonium nitrate in the explosive composition permits a reduction in the cost of the explosive composition while still providing an explosive composition that has good explosive characteristics (e.g. velocity of detonation) as well as good pumpability.

[0023] Accordingly, the explosive compositions of the instant invention have a higher energy, which increases heave and fragmentation compared to previous non-aluminized bulk water gels of the same density.

[0024] A further advantage of the instant invention is that the increased energy of the explosive composition permits an alteration in the drill pattern required at a blasting site. For example, essentially the same performance can be obtained at a reduced powder factor (i.e. in the amount of rock which is broken by an explosion using fewer holes) than would be required if a prior art watergels having the same density was used. Further, the pattern of the blasting may be expanded with no loss of fragmentation of heave.

[0025] The explosive composition of the instant invention also exhibits a shear-thinning rheology. Pursuant to this rheology, when the explosive composition is subjected to shear forces (e.g. the explosive composition is passed through a pump so as to load the explosive composition into a bore hole), the shear forces result in the viscosity of the explosive composition being reduced thereby facilitating the pumping of the explosive composition. When the shear force is removed, the viscosity increases. This results in reduced slumping (i.e. the explosive composition is less likely to flow into imperfections in a borehole). This reduced slumping can result in the explosive being less environmentally hazardous. For example, if less of the explosive composition seeps into cracks in the walls of the borehole, this will result in less low-order detonation or deflagration. The lower order detonation can result in toxic fumes being produced during detonation. Further, it is less likely that undetonated product will be left in the broken rock thereby reducing the environmental impact of utilizing the explosive composition.

[0057] In a preferred embodiment of the instant invention, the explosive composition comprises only 20 to 30 wt. % of a composition which is classified as being a booster sensitive explosive. Accordingly, a substantial portion of the ingredients for the explosive composition may be stored at site as a non-explosive thereby simplifying the storage of substantial quantities of the explosive composition at site.

Problems solved by technology

One disadvantage of some of the explosive compositions is limited sensitivity.