US2903969A - Method of blasting - Google Patents

Description

Sept.'15, 1959 F. F. KOLBE 3, v METHOD OF- BLASTING v Filed may 28. 1953, I

i INVENTOR.

.1 stituents.

United States Patent lVIETHOD OF BLASTING FrankF. Kolbe, Chicago, Ill., assignor, by mesne as- U signments, to The Maumee Collieries C0., a corporation "of )hio Application May 28, 1953, Serial No. 358,212. 22 Claims." cli ioz -zs ,.This invention relatesto a method of handling both liquid and solid ingredients 'which in combination form an explosive mixture. relates to amethod of positioning in a blasting hole,

having an angle above the horizontal, an explosive mix- '111116 of ammonium nitrate, a liquid hydrocarbon and nitrogen tetroxide.

" Because of its explosive power, its clean handling properties and itspready availability, ammonium nitrate is a naturally desirable solid component of explosive compositions. ;In addition to these physical attributes, am-

,monium nitrate possesses an advantageous chemical attribute infthat' when detonated it acts both as .a fuelfand' asg a ;source of oxygen Sinceinthe process of detona- 'tion some of this oxygen is in excess, I mix ammonium nitrate with a fuel suchas a hydrocarbon. l It is' an inherent advantage in composite explosives- More particularly,'this invention 1 those explosives consistingiof a plurality of constituents ch severally may be nonexplosive in n'at'ur'ethat the er [of "a j,premature explosion is minimized or elimihatedi 'lnere is a problem, however, in working with sucha composite explosive,which is a mixture of various constituents, of achieving a uniform intermixing of the components without a considerable degree of handling either of'the components as such -or of the explosive mix- "ture 'as. formed. S'uchhandling'pf unstable components or of the final composition obviouslyin'creases the possibilities of a premature and uncontrolled detonation. It, i is readily evident that the onlysafe explosive is one that is created for the first time'in ,situ. This can be achieved by working with a composite explosive if cer- "tain attendant difiicultiesi can be overcome. y

' There arefhowever, certain problems peculiar to blast-.

ing operations involving the use of such composite ex plosives, the fundamental problem relating to the bringing together of the several constituents at the desired situs in the blasting hole, and of bringing them together at thatpoint' at' the desired point of time. To avoid any and as nearly as possible to the given time for detonation.

fBy coordinating this admixture as closely as possible with the time'of detonatiohaany tendency that the material might have to. undergo self-detonation is reduced. Furthermore, losses due to volatilization or seepage of the reactant'is precluded or minimized. p

' Accordingly, it is an object of this invention to provide unnecessary risk, it is advantageous to bring such constituents into suitable admixture as quickly as possible,

2,903,969. Patented Sept. 15, 1959 "Ice liquid constituents into the blast hole in the order of their stability.

The foregoing objects have been achieved by myinvention which gains the advantages inherent ina composite explosive while at the same time overcoming the disadvantages. This is accomplished by my method, which makes possible the injecting of solid and liquid constituents including the combustibles and oxidants into a drilled I blasting hole. 1 Inthedrawing:

Figures 1 through 4 illustrate in diagrammatic form four alternative means and methods of packing a drill hole with explosive according to my invention as hereinafter described. a

- Specifically, my invention comprehends the use of amsuitable fuels, kerosene appears to be the optimum materi al under' normal conditions because of its greater physical stability, the other materials being somewhat more volatile; H

In the initial step of positioning the componentsin the 'drille'd blasting hole 15 (Fig. 1) according to my techniques, crystalline or pelletized ammonium nitrate 16,

which as a clean solid material is safely andeas'ily handl'ed, i's poured into the drilled hole. This material 'falls to. the'bottomof the hole where, as a crystalline solid, it has asubstantial amount of interstitial space between crystals. "For example, in cornmercial gradesofam- 'monium nitrate used for fertilizing soil there maybe about 40%' voids. Following this, kerosene, gasoline, or

others of the aforementioned fuels, or mixtures thereof,

are introduced either through a tube 17 which extends into the hole at least as far as the top of the ammonium nitrate accumulation or by merely pouring the kerosene on top of the ammonium nitrate. In this way, the kerosene flows into the interstitial spaces between the particles of ammonium nitrate and coats those particles. Preferably, suflicient kerosene is used that in addition to coating the particles of ammonium nitrate, there is a free amount which occupies a portion of the interstitial spaces.

When a tube is used to introduce the kerosene, it may be either rigid or flexible, or a combination of such types of tubing, since its purpose is to serve as a conduit. The

selection of the particular tubing to be used, need only be made with regard to the fact that the tubing must be of "such nature that its Walls will not unduly collapse from the forces imposed upon them by the stemming operation.

' With the tubing thus maintained in a position so that it extends as far into the hole as the top of the ama methodforpositioning'a composite explosive in a blast- *"It is afurther 'objectto providea supe'rior'method' for separately introducingthe severalliquid and solid constituents ofa composite explosive into a blasting hole.

RA further object istoprovide a safe and practical method for separately introducing the several constituents 0f a composite explosive into a blastinghole which method will permit optimum inter nixing of said conmonium nitrate bed, the hole is then stemmed around the, tubing with earth or other tamping materials 18.

It can thus be seen that during the tamping operations,

- there is no sensitive explosive composition in the drilled hole, only ammonium nitrate and kerosene being present.

A further' object of the inventionisto introduce the As an alternative step, the hole may be stemmed after the ammonium nitrate and tube are inserted, but before the kerosene is introduced through the tube. As a further modification of my method, the ammonium nitrate -and.some, or all, of the kerosene to be used may be mixed outside the blast hole and lowered as a composite mixture into the hole.

It ,will be advantageous in the application of my cording to Fig. 2.

method -when there is water or dampness, todispose the materials in a waterproof bag as seen in Fig. 2 preferably made of polyethylene or other similar plastic r nateri'al'sj 'with 5 said Ibag preferably. being'xas long-as, or longer than, the hole is deep. The bag has' a lower -closed"end and a diameter, :when expanded; greater. than -the 'diameter'of the-hole so "that when therbagris 'lowered' intorthe hole us'ually 'in 'a. collapsed formJ-and constituerits of the explosiveare introduced into the bag, th ey will not rupture it. The "bag; therefore,:-senves 'as ia linen and permits the explosive to fit closely: against the wall and bottom of the hole. In that wa'y,'-the'explosive is renderedcompletely waterproofed and also the liquid constituents arent lost through crevices; etc. Primacordiii-exemplifying the detonating type as con- -trasted" with an ignition type of-detonator,-maybe fastened along the vertical wall either on -the inside or the "outside of the bagbeforeit is-lowered into the hole.

"-being lowered to adjacent the top levelof the ammonium.

nitrate 36 inside-the bag--30, the .upper end A of thebag being collapsed aroundthe-tubes'and the-stem- =ming material 38 tamped into the holewSSaround. the tubes and upper end of the bag as in the modification ac- With the-tubing in place and the stemming ofzthe hole completed, the Primacord 19 (Fig:'1),.29 (Fig. 2), or :39 (Fig. 3) or other similar suitable detonator, is;'connected with wires to the-electrical switch. Nitrogen tetroxide is then run through the tubing and it descends to the bottom ofthe hole at which point it'goes .into solution with the kerosene to make an absolutely uniform solution of both liquids throughout the mass of ammonium nitrate "and producma compact explosive f column. Such complete intermixing of the liquid constituents, and thereby of all components of the explosive mixture, is due to the fact" thatfth'e' heavier 'nitrog'en tetroxide flows down through the lighter kerosene already surrounding the ammonium nitrate to produce, inelfect, "'a solid column of 'explosive-material,- any. void between the solid components being occupied bythe nquia' If desired, the tubing may be removed from the hole before blasting:

As was earlier stated, it is a particular- 'advan'tagelof my method that the liquid components are added in "order of their increasing densities so that the'heavier "will naturally intermix with the lighter. In tIiisregard,

thoroughly where the kerosene is introducedfifs't and *thed'ieavier nitrogen tetroxide, allowe'd1o"flow insubse- 'quently, it is also within the contemplation'of mymethod that,"=withthe ammonium nitrate in' place in the hole, a -"Y -connection 47B as seen in Fig.4 maybe made" at the fupper end 'of the tube 47 extending out of the hole'45 fthrough which the nitrogen tetroxidevialine 47C and kerosene via line '47D'frorn separate containers "may be allowed to run simultaneously-so as tomix as they enter 'fthe' blast-hole; I- may also meter thesimult-aneou'sly' introduc'edliquids in order to'properly' proportion them, fsirrc'ethe amounts are not identicalr"Alternatively, the "-jkerosene -may be poured from its containerinto"a"re- "'ceptacle, joined through a small hole irr'the: bottom to the upper end of the tube,"*andmixe'd therein with'nitrogen tetroxide added from its separate container.

f may'beadded' lastlyso as to minimize 'the losses due f; to volatilltyp' In the exemplified application, although "the'kerosene and nitrogen 'tetroxidear'e known to"'mix 4 The holeconnectingthe receptacle to the tube can be either kept closed until the two substances are mixed, or it can be left open when the kerosene is poured in because only a small amount of kerosene will run out before the mixture is complete. In this arrangement the opening from thekerosene container should be relatively small and that from the nitrogen tetroxide container relativelye-large. =1

Fieldltesting of-the method .ofintroducing the several. components into a:blastinglhole.has shown thatexcellent" control of one or more blasting operations being conducted in an area can be achieved. The nitrogen tetroxide-can be run--into the kerosenein-the blast hole or in a container directlyironna truck tank, but there are advantages in putting it in an individual container at each hole. The nitrogen tetroxide is prevented from running out of its container either by a valve or by 'a-'tubebeing looped and elevated above the-liquidlevel. Themither the valve or loop-can be manipulated-by hand; or -a distant controlg to letthe nitrogen tetroxide flow into the blast hole from one or a group of barrels. The-advantages ofjputting the' nitrogen tetroxide in "aseparate'container at each-blast hole-is that all 3 of the nitrogen, tetroxide containers can then be-opened simultaneously; 'or at approximatelythe same-time and "all holes; therefore, charged at the'same'time. Secondly, -it'is*anfiadditionahsafety precaution as-"no one need be near the blast hole while it being charged."

Itmay' be: seen'frorriv the foregoing description that by the method'of' my invention, acomposite explosive -can besafely' positioned at the bottom of a' blasting hole in such a way that all components of the explosive are in intimate and complete admixture. Accordingly, what I claimflas myinventioniis: v 1"1'. A method, of positioning in a blast hole acorn- -posite explosive containing ,soli'dand liquid components, .the liquidcomponents comprising one whichis denser 1 and moreunstable than another, which method .com-

prisesintroducing the-solid components in particulate form, introducing a..tube-into the hole .50 that its lower end is adjacent the top.of the solid. component, intro- .ducing the liquid components to the hole through .said .:-tube in the order of both their ascending densities and ascending instabilities.a

.2.'.The;method ofclaim 1 wherein thehole is stemmed atter; the introduction of the tube but before the liquid components areintroduced. m i ..-t..

3. The method of claim 1 wherein the hole is stemmed afterintroduction of the tube and prior to the introduction 'otlthe less stable liquid components. l1,

A method'of positioning in a blast hole acom -.posite explosive containing solid and liquidcomponents the liquid components comprising one which is-more unstable thananother, which-methodcomprises disposing in '.-,the blast hole'and extending upwardly from the bottom 'thereof a fiexible liner having its-lower end closed and having a diameter, when expanded, greater than'...,the -'diameter-of-saidhole at-the latters lower. end, and in -troducinginto said liner inthehole thesolid and liquid components to cause said:liner to expand into complete contact.with the adjoining-bottom and side walls of .the hole to form a solid column of explosive, .the solid component---beingintroduced -first, and the moremunstable one of'theliquid componentsbeing introduced last.-.

5. The method of claim 4 wherein the liner isextended from thebottom of theg-blast hole to a position adjacent the upperxend of thegblast hole 1 16-. Thenmethodnofr claim; 4 aWhfiI'fiiIl .the solidcomponent is :introducedin"particulateliorm and at least a portion of i the more {stable liquid components .is intro- -=-duced--into=lthe-liner in the hole mixed with the less stable liquid com'ponent 1 Y '4". A method ,of positioning in a blast hole a com- BQS ltQ explosiv GQIJtaining solid and liquid components,

the solid component comprising ammonium nitrate in particulate form and said' liquid components comprising a liquid hydrocarbon and nitrogen tetroxide, which method comprises disposing in the blast hole and extending upwardly from the bottom thereof a flexible liner having its lower end closed and having a diameter, when expanded, greater than the diameter of said hole, and introducing into said liner in the hole the ammonium nitra t e, liquid hydrocarbon and nitrogen tetroxide to cause said liner to expand into complete contact with the adjoining bottom and side walls of the hole to form a solid column of explosive, the'amrnonium nitrate being introduced first'and the'nitrog'en tetroxide last.

8. The method of claim 7 wherein the ammonium nitrate in particulate form is first poured into the liner in the blast hole after which a tube is inserted into the hole above the ammonium nitrate and the liquid. components are introduced to the liner through said tube.

9. The method of claim 8 wherein the blast hole is stemmed after the introduction of the tube but prior to the introduction of the liquid components.

10. The method of claim 8 wherein the blast hole is stemmed after the introduction of the tube and the liquid hydrocarbon but prior to the introduction of the nitrogen tetroxide.

11. The method of claim 7 wherein the liquid components are both introduced into the liner in the hole at the same time and are mixed while being introduced.

12. A method of positioning in a blast hole a composite explosive containing a solid component comprising ammonium. nitrate, and liquid components comprising kerosene and nitrogen tetroxide, which method comprises disposing in the blast hole and extending upwardly from the bottom thereof a flexible liner having its lower end closed and having a diameter, when expanded, greater than the diameter of said hole at the latters lower end, introducing into said liner in the hole the solid component, then introducing into said liner at least one tube, said tube having its lower end above the solid component, introducing into the liner by said one tube the kerosene, collapsing the upper end of the liner around said tube and disposing stemming material around the liner andtube, and then introducing through said one tube the nitrogen tetroxide.

13. A method of positioning in a blast hole a composite explosive containing solid and liquid components which comprises disposing in the blast hole and extending upwardly from the bottom thereof a flexible liner having its lower end closed and having a diameter, when expanded, greater than the diameter of said hole at the latters lower end, a detonating fuse having been secured to the vertical wall of the liner before introduction of the liner into the hole, and first introducing into said liner in the hole the solid and then inserting the liquid components through a tube to cause said liner to expand into complete contact with the adjoining bottom and side walls of the hole to form a solid column of explosive, said tube being inserted to adjacent the top of the solid component, the upper end of the liner being collapsed thereabout and stemming material inserted over andaround said collapsed upper end of the liner and tube before the insertion of the liquid component through the tube.

14. A method of positioning in a blast hole a composite explosive containing solid and liquid components which method comprises disposing in the :blast hole and extending upwardly from the bottom thereof a flexible liner having its lower end closed and having a diameter, when expanded, greater than the diameter of said hole at the latters lower end, introducing into said liner in the hole the solid component, then introducing into said liner at least one tube, said tube having its lower end adjacent the top of the solid component, introducing into the liner by said one tube the more stable liquid component, collapsing the upper end of the liner around said tube and disposing stemming material around the liner and tube, and then introducing through said one tubethe more unstableliquid component, said solid and liquid components causing said liner to expand into complete contact with the adjoining bottom and side walls of the hole to form a solid column of explosive.

, 15. A method of positioning in a blast hole a composite explosive containing solid and liquid components which method comprises introducing the solid component in particulate form to form a column which assumes the shape of the hole, introducing a tube into the hole so'that its lower end is adjacent thetop of the column of solid component, then stemming the hole, and thereafiter introducing the liquid component to the hole through said tube to mix with and substantially fill the voids between said particles of solid component.

16. A method of positioning in a blast hole a composite explosive containing solid and liquid components which method comprises disposing in the hole and extending upwardly from the bottom thereof a flexible liner having its lower end closed and having a diameter expandable to a diameter greater than the diameter of said hole at the latters lower end, introducing into said liner the solid component in particulate form to cause said liner to expand into complete contact with the adjoining bottom and side walls of the hole to form a column of saidsolid component which will have the shape of the hole, then introducing into said hole at least one tube to adjacent the top of said column of solid component, collapsing the upper end of the liner about said tube and against the top of said column, disposing stemming material about the tube and collapsed liner, and introducing the liquid component through said tube to mix with and substantially fill the voids between said particles of solid component.

17. A method according to claim 16 wherein a vent tube is additionally introduced to said hole and the upper end of the liner is likewise collapsed thereabout.

18. A method according to claim 16 wherein the liquid components comprise a more stable and a less stable liquid material and at least a portion of the more stable liquid material is mixed with the solid component before its insertion into the liner, and the less stable liquid material is introduced through the tube last.

19. In a blasting operation, the process which comprises charging a hole in a formation to be blasted with ammonium nitrate in particulate form and mixed with combustible material, the charge being surrounded by expandable means of polyethylene material which permits the charge to fit closely against the bottom and walls of the hole while completely protected from contact with water through said bottom and walls, causing the charge to compactly fill the hole to a desired level while so protected by the polyethylene material and fitting closely against the bottom and walls of the hole, stemming the charge and subsequently detonating said charge.

20. In a blasting operation, the steps comprising disposing in a hole in the formation to be blasted a flexible waterproof liner of polyethylene material having its lower end closed and having a diameter expandable to a diameter greater than the diameter of said hole at the latters end, charging said liner with a mixture of ammonium nitrate in particulate form and combustible material to compactly fill the same to a desired level, the liner of polyethylene material yielding so that said mixture fits closely against the bottom and walls of the hole while being protected against water present in the formation to be blasted, stemming the charge and subsequently detonating the charge.

21. In a blasting operation, the process which comprises charging a hole, in a formation to be blasted, with a free flowing explosive, the charge being surrounded by expandable means of polyethylene material which permits the charge to fit closely against the bottom and walls of the hole while completely protected from con-

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