Stability of “GLVVV” water-filled explosives containing aluminum in model waterlogged boreholes

Abstract

In recent years in the USSR there have been plans to extend the range for use of water-filled (slurry) explosives. From simple compositions containing an oxidant, water, and a sensitizer (akvatols, akvanits, ifzanites, and GLT compositions ), the explosives have been developed toward more efficient and energy-bearing types containing metal powders as combustible ballistic additives.It has been shown that replacement of part of the explosive sensitizer and oxidant in these compositions by high-energy metal combustibles is advantageous and economically justified. It increases the crushing action of water-filled explosives. The list of blasting materials released for continuous application in 1977 includes mechanically mixed hot cast water-filled explosives (WFE) --karbatol of grade GL-10V, including 15% of GOST [All-Union State Standard] ~058-73 aluminum powder. The presence of a thickening agent and a crosslinking agent in karbatol GL-10V enables us to charge blast holes containing static or slowly flowing water, but does not eliminate losses of ammonium nitrate (AN) from the charge while it remains in the water-laden hole. In waterlogged conditions, the process of charging boreholes with WFE based on a hot solution of oxidant by mechanized means can be effected as follows: a) charging from the blast-hole mouth; b) under a column of water; c) under a separating layer. Charging of WFE by the first method can be effected with a small amount of water (0.5-2.5 m) in the hole, part of which is trapped during charging and part displaced by the charge. In this case the AN losses from the charge are slight, and as a rule they do not affect the rock crushing quality. If the water column is higher, charging from the mouth leads to large AN losses from the charge (up to 95-100% ).If the WFE are injected under a column of water by the second method, the charge is compactly laid, displacing water as the borehole is filled. In this case, even if a thickening agent is used the AN loss from the charge is 10-15%; the height of the water column does not influence the AN losses, but does affect the injection pump power needed. To reduce the AN losses from the charge, as well as using thickeners and structureforming agents it is necessary to reduce the surface of contact between the charge and the water.Charging under a separating layer by the third method completely avoids contact between the WFE and the water and minimizes AN losses from the charge.At present the most widely used methods are charging from above (from the mouth) and under a water column; however, the second and third methods require powerful pumps to overcome the resistance of the water column. Practice has revealed that the pressure of the charge mixture at the end of the charging hose should be 2.5-3.0 atm. In this case there is no need for an attachment for withdrawing the charging hose.As well as reducing the AN losses from the charge during charging to a minimum, it is also necessary to keep the charge stable during the time up to the moment of explosion; this ...