US1841874A

US1841874A - Method of loading boreholes with explosives and means for working said method

Info

Publication number: US1841874A
Application number: US546363A
Authority: US
Inventors: Borchgrevink Otto Fredrik
Original assignee: Orkla Grube AS
Current assignee: Orkla Grube AS
Priority date: 1930-11-26
Filing date: 1931-06-23
Publication date: 1932-01-19
Anticipated expiration: 1949-01-19

Description

1932. o. F. BORCHGREVINK METHOD 0? LOADING BDR HOLES WITH MPLOSIVES I AND MEANS FOR WORKING SAID HBTKOD Filed June 23. 19:51

INVE TOR ATTORNEY Patented Jan. 19, 1932 OTTO FREDRIK BORCHGREVINK, OF LOKKEN VERK, NEAR TRONDHJEM, NORWAY, AS-

SIGNOZR- T0 OBKLA GBUIBE-AKTIEBOLAG, 0F LOKKEN VEBK, NEAR TRONDHJ'EM,

N ORWAY METHOD OF LOADING BOREHOLES WITH EXPLOSIVES AND METHOD 8 FOR WORKING SAID Application filed June 23, 1931, Serial No. 546,363, and in Norway November 28, 1980,

This invention relates to a novel method of loading bore-holes with explosives, and to means for working said method. The object of the invent-ion is to avoid the laborious and tardy loading of the bore-holes with blasting cartridges by aid of a loading rod.

According to the present method the explosives used for blasting are in pulverous or granular form, and are packed into the boreholes by aid of a compressed air injector or other device for blowing the explosives into the bore-holes. The explosives used hereto are preferably safety explosives or powders and other explosives which may be safely handled in this manner. The pulverous explosives, which may preferably be o fa somewhat stlcky nature in order to facllitate 1ts sticking to bore-holes drilled in upward direction, should prior to its use be sifted, in case they are of a lumpy nature, so as to remove all lumps. After being thus sievedor' in other manner disintegrated, the explosive is filled into the magazine of the injector device.

In the following, the method shall be ex plained with reference to the accompanying drawings:

Fig. 1 is a diagram of a compressed air inj ector, adapted for working the method, and

Figs. 2 and 3 are two sectional views of an apparatus for sifting lumpy explosives, said -sections taken at right angles to each other.

8 designates the compressed air injector, which may be of any suitable construction. 10 is the pulverous granular explosive filled into the injector, in order to be blown into the bore-hole 1. This explosive should preferably be sifted beforehand, so as to eliminate all lumps. The injector apparatus is as usual provided with an airtight lidand is fed with compressed air through a hose 12, con

nected to the injector by aid of a clutch-coupling 11 or other suitable coupling. From the injector, the explosive is blown to the borehole through a rubber hose 7 or other suitable hose. This hose is coupled to a blow-pipe 2 of a cross sectional area considerably smaller than that ofthe bore-hole. The length of the blow-pipe should approm' mately correspond to that of the bore-hole. When very long bore-holes are to be loaded, it may be practical to compose the blow-pipe of a plurality of pipe lengths screwed or otherwise coupled together.

In some cases the blow-pipe may be coupled direct to the injector apparatus.

In 'the opening of the bore-hole is fastened a tube 3, which may be somewhat tapering and be provided with a packing, so as to fit completely tight into the bore-hole. A filter bag 4 is slipped over this tube and the opening 5 is closed by placing a lashing or a rubber string around the tube. The filter bag is also at some distance from the opening 5 provided with an opening 6, somewhat larger than the cross sectional area of the blow pipe 2. The blow pipe is passed through this opening 6 in the filter bag and through the conical tube 3 into the bore-hole. The bag is lashed with a band or rubber string around the opening 6, but not so hard as to prevent drawing the blow pipe out of this opening. Compressed air may then be fed to the injector apparatus 8, thereby carrying the loose pullverous explosive with it into the bore- The blowpipe 2 may, as shown-in Fig. 1, be provided with an elongation 18, a sort offeeler, which may be formed as a copper rod or a slotted tube, having a bead in its end. With this rod 18 one ascertains, how far the filling is proceeding, without letting the end of the blowpipe come too near to the filling,

thereby reducing the amount of explosive,

carried back by the returning air current.

The pul-verous explosive is blown by the injector apparatus into the bore-hole with so great velocity that it will attach itself to the walls of the bore-hole andfill the same, densely packed. The deposition is facilitated by the fact that the cross sectional area of the blowpipe is so small compared with that of the bore-hole, the velocity of the return 21 feeds compressed air into the air jacket 25, surrounding the lower, conical part of the magazine, said conical wall being provided with numerous fine perforations. The air thus directed into the magazine serves to loosen the powder therein and to move 'it towards the nozzle 20. The air jacket 25 may, if necessary. be provided with openings for cleaning. A third cock 22 enables immediate interruption of the filling operation. A fourth cook 23, arranged at the top of the injector apparatus, is for letting out compressed air that might remain within the ap paratus after the cooks 19 and 21 have been closed. This cook 23 should preferably have a very fine bore in order that the air may escape without carrying with it parts of the contents of the magazine.

In case the bore-holes are filled with water, the apparatus may first be used for blowing out this Water by inverting the apparatus with the cock 21 locked. The compressed air will then pass the apparatus without carry ing explosives with it. For this operation the apparatus is used without an attached filter bag. After the water has been removed in this manner, the apparatus is again put in its normal position, and the filling operation isperformed as explained in the foregoing.

The water surface is also of course effected Wlk out the use of a filter bag.

During the filling of the explosive into the bore-hole the blowpipe is drawn back little by little,'whereby the degree of filling is with short intervals controlled by moving the feeler to and fro, until the filling operation has been completed.

As before mentioned, small quantities of the explosive will be carried back by the return air current, the quantity of the same depending on the more or less granular-consistence of the explosive and on its degree of stickiness. This part of the explosive is caught in the filter bag 4, so that practically nothing is wasted, the filter bag being provided with a third opening 19, through which the explosive gathered therein may be emptied without loosening the filter bag from the conical tube 3 and the blowpipe. Hereby time is saved, when many bore-holes are to be loaded. As soon as the bore-hole is filled to the desired extent, the compressed air is shut off. The parts of the injector and the blowpipe which are exposed to friction by the passage of the explosive should be made of copper or another metal or material unable to emit sparks, or they should be lined with such material. The magazine of the injector may be made of steel, but not itsnarrow lower portion and its nozzle.

As before mentioned, it will often be necessary to sift the explosive prior to filling it into filling of bore-holes situated below the the injector apparatus. It has been found that when such a sifting operation is performed a number ofthe explosives or blasting powders now in the market may be used for this loading method, in spite of their being of a rather sticky nature. A sifting apparatus especially adapted for this purpose is shown in Figs. 2 and 3. This apparatus consists of a square box 13, made of wood or a similar material; it is open at its upper end and its lower end is formed as a hopper. A drum 15 with projecting flanges, for instance of wood, provided with a cover of sifting netting of suitable mesh, so as to form a sifting drum, is fitted in between two sides of the box 13 and adapted to be rotated by a handle 17 or in any other suitable manner. A filling hopper 14 of wood or other suitable material is fitted into the top opening of the box 13, its lower end being shaped so as to conform with the curved surface of the sifting drum. The hopper 14: is filled with the more or less lumpy explosive which is then rapidly and efiectively sifted by rotating the sifting drum 16.

One wall 24 of the filling hopper 14 may suitably be made angular, so as to widen correspondingly the opening facing the drum, thereby increasing the capacity of the apparatus.

The method described in the foregoing may be used for the loading of boreholes drilled at any angle, and of any length used in practical blasting. Compared with the loading used to-day with cartridges and loading-rod, it is very time-saving and economical, and gives a packing eifect which is as good or better than that of the older method, and an improved density of loading, all cracks and cavities being likewise filled wholly or in art.

p The method is also safer than when using a loading rod, there being no possibility for damaging the slow-match or explosive charge with the loading rod, which is of frequent occurrence, when for instance a dctonating slow-match is to be inserted in a long borehole. The method has also the advantage, that when loading bore-holes which are more or less filled up with loose material, the blowpipe will easily be inserted where the bigger loading rod cannot pass. Also the pulverous explosive is easily blown into cracks and open cavities.

The economy of the method is also improved thereby that theprocess of converting the explosive into cartridges is dispensed with.

Claims 1. A method of loading-bore-holes with explosives, consisting in blowing explosives that have been subjected to,a sifting process into the blowholes by aid of blowing means.

2. A method of loading bore-holes with explosives, consisting in first sifting the explosives in a rotating drum sifter, and then blowing them into the bore-holes by aid of a compressed air apparatus.

3. A method of loading bore-holes with explosives, consisting in blowing the explosives into the bore-holes by aid of blowing means, comprising a blow-pipe of much smaller cross sectional area than that of the bore-holes, in which it is inserted.

4. A method of loading bore-holes with explosives, consisting in blowing the explosives into the bore-holes by aid of blowing means, comprising a blowipe of much smaller cross sectional area t an that of the bore-holes, in which it is inserted, said blowpipe being provided with a feeler, projecting from the end of said pipe for controlling the filling of the bore-hole.

5. Means for the loading of bore-holes with explosives, comprising a compressed air injector, a blowpipe connected to said injector by a pliable hose, said blowpipe being of a cross sectional area, smaller than that of the bore-holes, to' which it is to be applied.

6. Means for the loading of bore-holes, with explosives, comprising a compressed air injector, a blowpipe connected to said injector by a pliable hose, said blowpipe being of a cross-sectional area, smaller than that of the bore-holes to which it is to be applied, said blowpipe being provided with an elongation (a feeler) for the control of the loading operation.

7. Means for the loading of bore-holes with explosives, comprising a compressed air injector, a blowpipe connected to said injector by a pliable hose, said blowpipe being of -a cross sectional area, smaller than that of the bore-holes to which it is to be applied, an outer tube fitted into the mouth of the bore-hole, through which the blowpipe is inserted, said outer tube communicating with a filter receptaclefor recovering the parts of the explosive carried back by the return air current.

8. Means for the loading of bore-holes with explosives, comprising a compressed air injector, 'a blowpipe connected to said injector by a pliable hose, said blowpipe being of a cross sectional area, smaller than that of the bore-holes to which it is to be applied, an outer tube fitted into the mouth of the bore-hole, through which the blowpipe is inserted, said outer tube communicating with a filter receptacle for recovering the parts o f the explosive carried back by the return air current, said filter receptacle being provided with an opening for empg'ng the same without having to remove it om the said outer tube.

9. Means for the loading of bore-holes with explosives, comprising a compressed air injector, a blowpipe connected to said injector by a pliable hose, said blowpipe being of a cross sectional area, smaller than that of the bore-holes, to which it is to be applied, said injector comprising a magazine, provided with an air jacket for delivering compressed air into said magazine.

10. Means for the loading of bore-holes with explosives, comprising a compressed air injector, a blowpipe connected to said injector by a pliable hose, said blowpipe being of a cross sectional area, smaller than that of the bore-holes, to which it is to be applied, said injector comprising a magazine, provided with an air jacket for delivering compressed air into said magazine, said magazine being provided with perforations, communicating with said air jacket.

11. Means for the loading of bore-holes with explosives, comprising a compressed air injector, a pliable hose connected to the nozzle of said injector, and serving at the same time as a conveyor for the compressed air with the explosive suspended therein, and as a blowpipe. 4

In testimony whereof I have signed my name to this specification. I OTTO FREDRIK BORCHGREVINK.