US3093197A - Method and apparatus for thermally working minerals and mineral-like materials - Google Patents

Description

un 1, 1963 D. c. FREEMAN, JR.. ETAL 3,093,197

METHOD AND APPARATUS FOR THERMALLY WORKING MINERALS AND MINERAL-LIKE MATERIALS Filed Dec. 9, 1958 2 Sheets-Sheet 1 INVENTORS ONALD C FREEMAN,JR. OSEPH A.SAWDYE m Z%TOR EV s 4H; 4 r ww mm Mug-Mg W 4. I

7 3 z 2 2 9 1 h 0; w B imfi 1 1 p 3 June 11,1963 D. c. FREEMAN, JR.. ETAL 3, 7

METHOD AND APPARATUS FOR THERMALLY WORKING MINERALS AND MINERAL-L IKE MATERIALS Filed Dec. 9, 1958 2 Sheets-Sheet 2 72 Q Gas V' (D' -Warer M f &Cam

9 Tank Micro Swirch Blowtorch V JOSEPH A. SAWDYE ATTO NE) INVENTORS DONALD C. FREEMAN, JR.

United States Patent Patented June 11, 1963 This invention relates to a novel method of and apparatus for thermally working a mass of mineral or mineral-like material, and more particularly to thermally working diflicultly spallable rock by the impingement of a high velocity jet flame.

Previously, minerals and mineral-like substances have been thermally worked or pierced by applying a high velocity jet flame to localized areas and progressively advancing the heat into the substance to heat the freshly exposed area as separated material is progressively removed by a stream of hot gases. Thermal working of rock proceeds by either of two methods, a spalling process or a melting process, depending on the substance to be worked. Materials having relatively high melting points, large grain structure and few extraneous material inclusions, such as quartzite, dolomite, quartz or chert, are easily spalled. However, there are other materials which tend to melt instead of spall when subjected to intense heat, and thus may be termed diflicultly spallable. Rocks falling into this category include certain kinds of granite, taconite, and anorthosite. -It should also be recognized that some rocks include both types of material, e.g. seams of difficultly spallable material distributed in the body of easily spallable rock. Easily spallable materials can be readily separated from the base rock and removed from the hole by hot gases by the aforementioned method which is described in more detail in US. Patent No. 2,675,993 to G. H. Smith and W. I. Mitchelh However, a serious problem is encountered when attempting to utilize this method for the thermal working of diflicultly spallable materials. It has been found that when a jet flame is directed at one point on a rock for more thanafew seconds, areas of melt are formed. In easily spallable rocks, the area of melt is small, but in difficultly spallable rocks the entire surface under the flame may melt. This presents a severe limitation for the known thermal working methods because the melt areas form a heat resistant layer which tends to remain on the rock surface as an insulator and retards further piercing.

It should also be recognized that adjacently located rock beds may contain material having varying degrees of spallability, mally working difficultly spallable material should be readily adaptable for piercing easily spallable rock. Furthermore, it will be appreciated that a large quantity of equipment is presently being used for thermally working easily spallable material, and such equipment should be employed in any improved method for working difficultly spallable material to maximize operating efficiency and minimize additional investment costs.

so that any method and apparatus for ther- .high velocity jet flame.

will be apparent from the ensuing description and appended claims.-

In the drawings:

FIG. 1 is a view of a longitudinal section of a novel blowtorch for performing a method embodiment of the invention, taken along the line 1-1 in FIG. 2;

FIG. 2 is a view of the end of the blowpipe of FIG. 1 as seen from the bottom; and

- FIG. 3 is a view of a longitudinal fragment section of an-alternative form of a blowpipe within the invention;

FIGURE 4 is a schematic diagram of a typical water injection system.

According to a method embodiment of the present invention, material is separated from a mass of difficultly spallable rock by applying an alternately hot and cool high "velocity jet flame of combustion gases against such mass.

The particles which are initially melted and fused by the hot flame are rapidly quenched by the succeeding relatively cool flame and broken oil for removal by hot gases before they can spread into relatively large areas of melt and form insulating layers which are diificult to pierce. Thus, spalling may be resumed immediately between the coolant injections.

In a preferred embodiment, an oxidizing agent and fuel are introduced into an enclosed combustion zone of a burner and burned therein to form combustion gases. A coolant such as water is intermittent-1y injected into the combustion zone to cool the combustion gases. The resulting alternately hot and cool combustion gases are discharged from the combustion zone first through a flow restriction zone and thenthrough an expansion zone as a The alternately hot and cool jet flame is then impinged against the rock mass to separate material therefrom and rapidly quench the initially molten particles thereby substantially preventing the formation of diflicultlyworkable melt zones. The separated material is removed from the mass atleast partially by said coolant, which in thecase of water is in the form of ejecting steam. The burner is then advanced along a selected path to separate and remove additional material from the mass along such path. Alternatively, the coolant may be injected'into the high velocity jet flame downstream of the combustion zone although injection directly into such zone is preferred from the standpoint of piercing efliciency. The temperature of the hot combustion gas jet is preferably at least about 4,000 and the temperature'of the cool combustion gas jet ispreferably between about 100 and 900 F. Also, the jet flame impinging. against the rock mass preferably has a velocity of at least about 2,500 feet per second so as to obtain the preferred jet piercing action. 1

Referringnow to the drawings and. particularly to FIGS. 1 and 2, one novel internal combustion blowtorch B suitable for performing the method of the invention comprises a burner nozzle N including a core 11 I .its upper end tapering gradually downward to a re- It is, therefore, the main object of the present invenstricted central injector throat- 15 which forms an entrance into a relatively large bulbous combustion chamber 17. The walls of combustion chamber 17 in turn converge downwardly to a discharge path 18 comprising 'a throat section 19 remote from throat 15 and an expansion section 20 flaring downwardly from throat section 19 without restriction to a discharge orifice or exit 21 in the lower end of the nozzle.

Fuel, such as relatively inexpensive kerosene, is in jected' at a positive pressure greater than 15 pounds per square inch through the first throat 15 into the combustion chamber 17 by an injector. nozzle 22 which is threaded into a fuel supply duct 23 in an adaptor body 27 and projects into the inlet bore 13 in axial alignment 3 with throat and combustion chamber 17. An oxidizing agent such as gaseous oxygen is concurrently but separately delivered at a positive pressure greater than 15 pounds per square inch to the inlet bore 13 through an eccentrically arranged oxidizing agent supply duct 25 in adaptor 27. The fuel and oxidizing agent mix intimately together in passing through throat 15, and the mixture burns vigorously in chamber 17 at a combustion pressure greater than 15 pounds per square inch, producing large volumes of flaming combustion gases which rush at high velocity through the discharge throat section 19 and the flaring expansion section 20 to provide an axially directed flame jet having a jet linear velocity of at least about 2,500 feet per second. The high velocity flame jet passing through flaring expansion section 20 and emanating from exit 21 is intermittently cooled by jets of a coolant such as water which are injected into the flame through downwardly inclining ducts 27a circumferentially located around the lower end nozzle core 11. The injected water is flashed to steam and aids in the ejection of separated material from the working zone in addition to its primary function of intermittently cooling the flame jet discharged through nozzle exit 21. Ducts 27a are fed through annular ring-like chamber 27b which in turn communicates with coolant passageway 27c extending through substantially the entire length of sleeve 26. Coolant passageway 27c terminates at its upper end in a nipple 27d which is coupled to a conventional swing joint 27e. Connected to the swing joint 27e is a conduit 27; which communicates with passage 27!: in core 49. Water is supplied from an injection system (see FIGURE 4) to the passage 27]: by including an annular chamber 27 as a portion of the passage 27!: between the core 49 and the barrel 48 so that the portion of the passage 27h in the core and chamber 27j in the barrel are always in register as the core rotates. Coupling 27k connects annular chamber 27 with a conduit 27m which contains means for providing pulses of water therethrough, such means being for example a solenoid valve 27g. The operation of this valve will be well understood by those skilled in the art, and may for example be controlled by a cam-operated switch (see FIGURE 4) providing a very short, square-wave pulse of water into the flame jet. The injected water may for example be pressurized with a mechanical pump, by means of gas pressure in a water reservoir tank, or by other convenient means. The quantity of water injected per cycle can for example be adjusted by altering the pressure on the water injection system above the pressure of the jet flame.

Referring to FIGURE 4, a tank 70 containing water to be injected is pressurized by means of a gas supplied through conduit 72 to the tank 70. Regulator 71 positioned in conduit 72 controls the pressure in the tank 70. Solenoid valve 27g is connected in the outlet conduit 73 from the tank 70. The valve 27g is controlled by a camoperated switch 74 which makes and breaks the circuit 75 to the solenoid valve 27g to open and close such valve and thereby produces the pulse of water injected.

The flame will continue to burn even when plunged into water as in a flooded hole. Also, the nozzle of the preferred internal combustion burner of the present invention is less subject to functional damage by flying detritus and by impacting against the bottom of a pierced hole than are external combustion burners.

More in detail, core 11 of burner nozzle N is threaded into a tightly fitting di'sintegrator sleeve 26 which terminates at its lower end with the lower end of the core 11. At itsupper end, sleeve 26 projects beyond core 11 and is threaded over adaptor body 27 to hold the upper end of i the core tightly against the lower face of the adaptor body with a fluid tight seal in such a position that injector nozzle 22 and oxidizing agent duct are both in register with the bore 13. V

The nozzle N is cooled by water or other fluid coolant supplied through a pair of ducts 28 and 29 in adaptor body 27 to an annular header chamber 31 bounded by a ridged inner wall section of sleeve 26 and the inwardly beveled top outer portion of core 11. A series of circumferentially arranged vertical ducts 31a through the enlarged upper section of core 11 pass the water to an annular cooling jacket 31b bounded by the inner wall of sleeve 26 and the outer wall of the lower section of core 11. Water leaves the nozzle through a group of circumferentially arranged upwardly and outwardly inclined ports 36 establishing communication between the nozzle cooling jacket 31b and the outer surface of the sleeve 26 close to the lower end of the nozzl N. The water discharged through ports 36 aids in cooling the slag for disintegration by physical impact. Steam formed by contact of the hot material helps the gaseous products of combustion to eject detritus from the hole. In the case of small diameter burners, a portion of the cooling water must be piped back up the burner and not passed into the hole. This is because the minimum required water flow for cooling is too great to be blown out of the hole by the combustion gases.

For assisting the piercing of a hole, as by breaking up any cooled slag by physical impact therewith and as by reaming the wall of the hole, radial teeth 37 extend longitudinally along the outside of sleeve 26 to its lower end. Several of the water discharge ports 36 are preferably positioned between each pair of teeth.

Water is supplied to the ducts 28 and 29 in adaptor 27 through a long sleeve 39 acting as a torque tube secured at its lower end to adaptor body 27, and at its upper end to an upper body A having a passageway 40 establishing communication between the interior of sleeve 39 and a hose connection nipple 41.

Kerosene or other fluid fuel is supplied to duct 23 through a tube 42 which extends through sleeve 39 and is secured at its ends to the adaptor body 27 and the upper body A. A passageway 43 extends between tube 42 and a hose connection nipple 44 on body A.

Oxygen passes to duct 25 through a second tube 45 arranged within sleeve 39 alongside of tube 42 and secured at its ends to the adaptor body 27 and the body A. A

passageway 47 in body A carries oxygen to tube 45 from a hose connection nipple 46.

When piercing diflicultly spallable rock by an alternately hot and cool jet of combustion gases emanating from nozzle N, quenching the initially molten particles by the cool jet and preferably also by water from ports 36, and disintegrating the quenched material mechanically by physical impact with teeth 37, it may be advantageous to rotate the teeth automatically as the burner advances to form successive portions of the hole. For this purpose, the upper body A is constructed with an external nonrotating barrel 48, and a core 49 is journalled within barrel 48 for rotation therein. It is to the lower end of core 49 that the sleeve 39 and tubes 42 and 45 are se cured, so that they and the burner nozzle N all rotate with the core. Core 49 is held in barrel 48 by a flange 51 on its lower end and bearing against a plate 54 on the top of the barrel.

Water is continuously supplied to sleeve 39 during its rotation by including an annular chamber 55 as a part of passage 40 between the core 49 and the barrel 48 so that the portions of the passage 40 in the core and chamber 55 in the barrel are always in register as the core rotates. An identical construction using an annular passage 56 is employed for the passage 47 which supplies oxygen to tube 45 as the core rotates. Packings 57 of conventional design are provided between the core 49 and barrel 48 above and below the registering portions of passages 40 and 47 to prevent leakage.

Fuel passage 43 terminates at its upper end in a nipple 59 which is coupled to a conventional swing joint 60 designed to permit nipple 59 to rotate while kerosene is supplied continuously without leakage from the nonrotating hose connecting nipple 44.

One important advantage of the various blowtorch embodiments of the present invention is that they are suitable for thermally working both easily and difiicultly spallable materials. For example, the blowtorch of FIGS. 1 and 2 having been used for thermally working difiicultly spallable material may be moved to a different rock bed for thermally working material which can the easily spalled without the aid of intermittent coolant injection. Thus, by simply closing solenoid valve 27g, the blowtorch of the present invention may be readily used for thermal working easily spallable material. Furthermore, it should be recognized that the spalling efliciency of some easily spallable material may be improved by intermittent coolant injection.

In a modified type of burner nozzle N shown in FIG. 3, the oxidizing agent and fuel are introduced through bore 113 into cylindrical combustion chamber 117 for mixing and burning therein to form combustion gases. Such gases are periodically cooled by a coolant stream injected into chamber 117 through horizontal ducts 127a circumferentially located around the nozzle periphery. The ducts are fed by an annular cooling chamber 127b secured to the outer walls of nozzle N near the lower end thereof, and such chamber is in turn charged with coolant through opening 170. An injection system similar to that shown in FIGURE 4 is connected .to nozzle N through opening 170. It has been found that satisfactory results are obtained when water coolant is injected into the combustion zone 117 at a frequency of between about and 150 pulses per minute, and preferably between about 80 and 110 pulses per minute. If the coolant injection rate is below the above-mentioned range, essentially no quenching action is obtained; on the other hand if the rate exceeds this range, the combustion gas efliuent does not reach sufficiently high temperatures for efiective heating of the mineral substance. Nozzle N itself is cooled by water injected through conduit 141 for flow through annular passageways 1'31b and discharge through another conduit connected to outlet opening 171.

The alternately hot and cool combustion gases are discharged from combustion chamber through discharge path 118 including flow restricting throat section 119 and expansion section 120 for discharge from the nozzle N through exit orifice 121 as a high velocity flame jet. It is to be noted that in the nozzle N of FIG. 3, the coolant is injected into the combustion chamber, whereas in the nozzle embodiment of FIGS. 1 and 2, the coolant is injected into the high velocity flame jet. The first-mentioned embodiment is preferred since it has been found that cooling of the combustion gases is more efiicient and more easily controlled if effected in the combustion chamber.

Although radial teeth for reaming the walls of a hole are not illustrated in the nozzle embodiment of FIG. 3, it is to be understood that teeth similar to those shown in FIGS. 1 and 2 would be provided. It will be recognized some blowtorches for thermally working difiicultly spallable material will not require radial teeth nor rotating nozzles; consequently these features are not considered essential to the present invention. For example, blowtorches used for certain jet channeling and thermal texturing operations would fall in this category.

Furthermore, it will be understood by those skilled in the art that blowtorch nozzles having multiple combustion chambers and/ or multiple discharge paths may be readily used in the method and apparatus embodiments of the present invention.

In the following specific examples, the advantages of this invention for thermally working various materials are illustrated:

EXAMPLE I A blowtorch having a nozzle similar to that illustrated in FIGS. 1 and 2 was constructed so that water could be injected into the flame jet discharge path from a one-inch diameter combustion chamber processing a combustible gas mixture ofoxygen and propane at a rate of 160 cubic feet of oxygen per hour and 60 cubic feet of propane per hour. Water was injected into the flame about once per second at a rate of about two gallons per hour, and it was shown that the spalling characteristics of the flame were improved. Several shallow holes were drilled in diflicultly spallable granite, and areas of melt were cooled to below incandescence almost instantaneously by the water pulse, While the spalling action resumed immediately between injections of water. The rate of piercing was higher with water injection, and the holes were free of melt areas and more uniform than when piercing was attempted without water injection.

EXAMPLE II A blowtorch having a nozzle similar to that illustrated in FIG. 3 was constructed so that water could be injected into a combustion chamber having a volume of about-3.4 cubic inches, burning a combustible mixture of oxygen and propane at a combined rate of about 220 cubic feet per hour. Cutting of a channel in Opalescent Granite, a diflicultly spallable material, was attempted Without Water injection but such cutting was soon stopped due to melt formation which impeded further progress. Another channel about 16 inches long, 2 /2 inches wide, and 2 /2 inches deep was made using water injection; this channel showed no signs of excessive melt formation or slower spalling until considerable penetration of the test rock and extensive cracking had occurred. Even then the formation of melt was not so severe as to prevent further channeling. During this test, water was injected into the combustion chamber at a frequency of about pulses per minute in a quantity of about 2.5 gallons per hour.

EXAMPLE III In this series of tests, the same blowtorch used in the jet channeling experiments of Example II was used for jet piercing holes in Opalescent Granite and Scotstown Granite, both materials having poor spalling characteristics. Oxygen and propane were introduced into the combustion chamber at a combined rate of about 220 cubic feet per hour. The water pressure on the injector was varied from a maxium of'240 p.s.i.g. to 112 p.s.i.g. minimum. Since the water pressure controls the actual volume of water injected, these holes compared with those made without water injection graphically demonstrate the latters effect. In evaluating the piercing rate in a specimen, at least three holes Were preferably drilled between six and fifteen inches deep. The rock removal rates (inches per ft. 0 were then determined by measuring the volume of the hole. The following results were obtamed:

Rock Water Bock sample removal injection InjJmin.

rate pressure (infi/ftfiOz) (p.s.i.g

Opalescent Granite 0.225 D0 0.188 0.863 150 100 1.350 200 100 0.975 240 84 0.785 112 84 0.831 200 84 0.0 0.0 0.8 250 1.4 200 90 The tabulated data indicates that water injection has a beneficial effect on diflicultly spallabe rock such as Scotstown Granite and Opalescent Granite. In piercing both these stones without coolant injection, melt forms almost immediately and prevents any further progress into the stone. By using water injection, no melt is formed and upon completion of the hole the bottom is clean. The hole piercing apparently could be continued for any length of time.

Specific examples have been described above to illustrate the principles of the invention. It is to be understood that the invention is not limited to the features specifically described but that changes can be made in the construction and arrangement of parts in the blowtorches, and in the steps of the method. For example, instead of injecting a coolant into the combutsion zone (FIG. 3) or the jet flame of the burner nozzle (FIG. 1), the coolant may be injected into the jet externally from such burner nozzle.

What is claimed is:

1. A method of thermally working a mass of difficultly spallable rock which comprises introducing an oxidizing agent and fuel into an enclosed combustion zone in a burner; burning said mixture in such zone to form combustion gases; intermittently injecting a coolant into the combustion zone to cool the combustion gases; discharging the resulting alternately hot and cool combustion gases from said combustion zone first through a flow restriction zone and then through an expansion zone as high velocity jet flame; impinging the alternately hot and cool jet flame against said mass to separate material therefrom and rapidly intermittently quench the initially molten particles thereby substantially preventing the formation of diflicultly workable melt zones; removing the separated material from said mass at least partially by said coolant; and advancing said burner along a selected path to separate and remove additional material from said mass along said path.

2. A method of thermally working a mass of diflicultly spallable rock which comprises introducing an oxidizing agent and fuel into an enclosed combustion zone in a burner; burning said mixture in such zone to form combustion gases; discharging such gases from said combustion zone first through a flow restriction zone and then through an expansion zone as a high velocity jet flame; intermittently injecting a coolant into such jet so as to form an alternately hot and cool jet flame; impinging such jet flame of varying temperature against said mass to separate material therefrom and rapidly intermittently quench the initially molten particles thereby substantially preventing the formation of difiicultly workable melt zones; removing the separated material from said mass at least partially by said coolant; and advancing said burner along a selected path to separate and remove additional material from said mass along said path.

3. A method according to claim 1 for thermally working a mass of diflicultly spallable rock, in which water is said coolant and is intermittently injected into the combustion zone at a frequency of between about 10 and 150 pulses per minute.

4. A method according to claim 1 for thermally working a mass of diflicultly spallable rock, in which water is said coolant and is intermittently injected into the combustion zone at a frequency of between about 80 and 110 pulses per minute. 7 g g 5. In apparatus for thermally working a mass of diflicultly spallable rock, a. blowpipe having means for impinging high velocity jet flame against said mass, means for injecting coolant into said jet flame, and control 8 rneans associated with said last-named means for pro- 'viding pulses of coolant to said jet flame.

6. Apparatus asclaimed in claim 5, in which said pulse providing means comprises a solenoid valve.

7. A rock working blowtorch comprising a body having a first end and a second end and having at least one inlet at said first end thereof for oxidizing agent and fuel fluids; a combustion chamber in said body for burning of such fluids to form combustion gases therein; at tleast one passageway for such fluids and communicating .at opposite ends with the fluid inlet at the body first end and an inlet to said combustion chamber; at least one coolant passageway through the blowtorch body wall and communicating at one end with said combustion chamber, means for intermittently interrupting the flow of a fluid coolant from a supply thereof to said coolant passageway for intermittently injecting at sufficient pressure and mixing such coolant with the combustion gases in said chamber so as to intermittently cool such gases; a discharge path from the combustion chamber for emitjting an alternately hot an d cool high velocity jet flame from said second end of the blowtorch body, including a flow restricting throat section communicating with the combustion chamber and an exit expansion section comjmunicating with such throat section for accelerating the alternately hot and cool combustion gas stream to form 'the high velocity jet discharge flame.

8. A rock working blowtorch comprising a body having a first end and a second end and having at least one inlet at said first end thereof for oxidizing agent and .lfuel fluids; a combustion chamber in said body for burning of such fluids to torm combustion gases therein; at "least one passageway forsuch fluids and communicating at opposite ends with the fluid inlet at the body first end and an inlet to said combustion chamber; a discharge path from the combustion chamber for emitting a high velocity .jet flame from said second end of the blowtorch body, including a flow restricting throat section communicating with the combustion chamber and an exit expansion zone communicating with such throat section for accelerating the combustion gas stream to form the high velocity jet discharge flame; at least one coolant passageway through the blowtorch body wall and communicating at one end with said discharge path; means for intermittently interrupting the flow of a fluid coolant from a supply to said coolant passageway for intermittently injecting at a suflicient pressure and mixing said coolant with the combus- 'tion gases in said discharge path so that the jet discharge flame is alternately hot and cool.

References Cited in the file of this patent UNITED STATES PATENTS 65,677 Johnson et a1 June 11, 1867 :1 ,0254129 Sutton Apr. 30, 1912 21 1 1,872 Rea Mar. 22, 1938 2,548,463 Blood Apr. 10, 1951 2,659,923 1Wilson Nov. 17, 1953 2,675,993 Smith et al Apr. 20, 1954 2,976,941 Horton Mar. 28, 196i

Claims (2)

1. A METHOD OF THERMALLY WORKING A MASS OF DIFFULTLY SPALLABLE ROCK WHICH COMPRISES INTRODUCING AN OXIDIZING AGENT AND FUEL INTO AN ENCLOSED C~MBUSTION ZONE IN A BURNER; BURNING SAID MIXTURE IN SUCH ZONE TO FORM COMBUSTION GASES; INTERMITTENTLY INJECTING A COOLANT INTO THE COMBUSTION ZONE TO COOL THE COMBUSTION GASES; DISCHARGING THE RESULTING ALTERNATELY HOT AND COOL COMBUSTION GASES FROM SAID COMBUSTION ZONE FIRST THROUGH A FLOW RESTRICTION ZONE AND THEN THROUGH AN EXPANSION ZONE AS HIGH VELOCITY JET FLAME; IMPINGING THE ALTERNATELY HOT AND COOL JET FLAME AGAINST SAID MASS TO SEPARATE MATERIAL THEREFROM AND RAPIDLY INTERMITTENTLY QUENCH THE INITIALLY MOLTEN PARTICLES THEREBY SUBSTANTIALLY PREVENTING THE FOR-

5. IN APPARATUS FOR THERMALLY WORKING A MASS OF DIFFICULTLY SPALLABLE ROCK, A BLOWPIPE HAVING MEANS FOR IMPINGING HIGH VELOCITY JET FLAME AGAINST SAID MASS, MEANS FOR INJECTING COOLANT INTO SAID JET FLAME, AND CONTROL MEANS ASSOCIATED WITH SAID LAST-NAMED MEANS FOR PROVIDING PULSES OF COOLANT TO SAID JET FLAME.

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