This invention relates to a blast hole receptacle and a blast hole device. The invention also relates to a blast hole device installation.

The invention is expected to be particularly advantageously applicable to blasting in open-cast mining such as coal mining. Accordingly, such applications should particularly, but not exclusively, be borne in mind when considering this specification.

BACKGROUND OF THE INVENTION:

Generally, blasting in mining is conducted by inserting charges into blast holes for later detonation. Such charges are typically made of an Ammonium Nitrate and Diesel mixture.

To streamline the blasting process, an array of blast holes is usually drilled and filled with charges for the later synchronous detonation of the charges. In such scenarios, the time lapse between the inserting of charges and the actual detonation process poses a risk of uncontrolled spontaneous combustion or explosion of charges due to ambient subsoil temperature conditions of the blast holes.

The inventor has identified a need for reducing the risk of premature detonation during blasting preparations. Accordingly, the present invention aims to overcome this risk by providing a device for stabilizing the thermal condition of explosive charge loads. SUMMARY OF THE INVENTION:

In accordance with the invention generally, there is provided a blast hole receptacle having at least one insulated side wall.

The blast hole receptacle may include an insulating base and an open top.

More particularly, according to a first aspect of the invention, there is provided a blast hole receptacle which includes: at least one insulating side wall; an insulating base; and an open top having a circumferential top edge.

The blast hole receptacle may be substantially tubular.

The at least one insulating side wall may include any one or more of: a layered insulating side wall and a composite insulating side wall. Likewise, the insulating base may include any one or more of: a layered insulating base and a composite insulating base.

The layered insulating side wall may include at least one fluid or semi-solid layer.

The layered insulating side wall may include at least one air layer.

The at least one semi-solid layer may include a gel layer.

The gel layer may include a gel of which the main ingredient is Potassium Polyacrylate. The Potassium Polyacrylate-based gel may be mixed with a number of others to ensure its heat-reducing properties. The at least one insulating side wall may be of stiffened paper construction.

The insulating base may be of plastic construction, for example moulded plastic construction.

The at least one insulating side wall and insulating base may be integrally formed as a unitary construction.

According to another aspect of the invention there is provided a blast hole device which includes: a nested plurality of blast hole receptacles of decreasing size as hereinbefore described.

The blast hole device may include a round for locating the open tops of the nested plurality of blast hole receptacles.

To this end, the round may include a corresponding number of annular recesses wherein the circumferential top edges of the nested plurality of blast hole receptacles are located. To this end, the number of annular recesses may be provided by corresponding profiles in the round and wherein the circumferential top edges are received.

The round may be a spacer round.

The spacer round may define a lid for operative closing of the open top of at least one of the blast hole receptacles.

The spacer round may be of plastic construction, for example moulded plastic construction.

According to another aspect of the invention there is provided a blast hole device installation which includes: drilling a blast hole; inserting the blast hole device into the blast hole; and placing an explosive charge in the blast hole device.

Advantageously, the blast hole device may be pre-manufactured off-site and transported to the blast site to facilitate and speed up blasting operations.

The invention is now described, by way of non-limiting example, with reference to the accompanying diagrammatic drawings.

DRAWINGS:

In the drawings,

Figure 1 illustrates, schematically, a three-dimensional view of a blast hole device in accordance with one aspect of the invention.

Figure 2 shows a sectional side view of the blast hole device of figure 1 according to another aspect of the invention.

Figure 3 shows, schematically, a three-dimensional exploded view of the blast hole device in accordance with yet another aspect of the invention.

In the drawings, like reference numerals denote like parts unless otherwise indicated.

DETAILED DESCRIPTION OF THE INVENTION:

In figure 1, reference numeral 10 denotes, generally, a blast hole device in accordance with one embodiment of the invention. The blast hole device 10 is shown here in its assembled form and comprises a nested plurality of blast hole receptacles of decreasing size, of which only an outer blast hole receptacle 12 can be seen here. The outer blast hole receptacle 12 includes an insulating side wall 14, an insulating base 16, an open top 18 having a circumferential edge 20, and a spacer round 22 for locating the circumferential edge 20. With reference to figure 2 of the drawings, reference numeral (30) denotes generally a sectional side view of the blast hole device (10) of figure 1. The blast hole device (30) comprises a nested plurality of blast hole receptacles of decreasing size, which, in this particular embodiment amounts to three blast hole receptacles namely an outer blast hole receptacle (12) having a layered insulating side wall (14) filled with a gel, an insulating base (16), and a circumferential top edge (20); a smaller blast hole receptacle (32) having a layered insulating side wall (36) filled with a gel, an insulating base (40), and a circumferential top edge (42); and a still smaller blast hole receptacle (34) having a layered insulating side wall (38) filled with a gel, an insulating base (44), and a circumferential top edge (46). The blast hole device (30) has a spacer round in the form of a plastic moulded spacer round (22) which includes a corresponding number of annular recesses wherein the circumferential top edges (20), (42) and (46) of the nested plurality of blast hole receptacles (12), (32) and (34) are located. To this end, the number of annular recesses is provided by corresponding profiles in the spacer round (22) wherein the circumferential top edges (20), (42) and (46) are received.

Turning to figure 3 of the drawings, numeral (50) denotes an exploded three- dimensional view of the blast hole device (30) of figure 2.