US2740609A - Apparatus for the removal of cuttings from drill holes - Google Patents

Description

April 1955 A. s. RICHARDSON ET AL 2,740,609

APPARATUS FOR THE REMOVAL OF CUTTINGS FROM DRILL HOLES Filed March 6, 1952 1, ,4. ATTORNEYS APPARATUS FOR THE REMOVAL orcurrmos FROM DRILL HOLES Allan S. Richardson and William C. Williamson,

Butte, Mont. I 1

Application March 6, 1952, Serial Nae-15,042 1 Claim. c1. 255-40 This invention relates to improved apparatus for the removal of rock cuttings from holes being. drilled dry in the earth. Essentially the apparatus comprises a combination of means to introduce compressed air into the hole being drilled, to blow the cuttings up the hole, a hood surrounding the mouth of the hole, and suction means connected to the hood to draw the stream of airborne cuttings away from the mouth of the hole and thus to remove the dust and cuttings from theimmediate vicinity of the drilling operation. The invention provides improvements in the form of a rock trap to separate large rock cuttings out of the air stream and a dust collector wherein the fine rock cuttings can be collected in a water slurry.

It is advantageous in many situations to drill holes in rock dry rather than with the use of water or other drilling liquid. Particularly in the case of shallow vertical holes, such as those drilled for the placing of explosives, it is generally easier to remove rock cuttings from a dry-drilled hole by means such as a blast of compressed air than it is to remove such cuttings when compacted into a mud by wet drilling. In some localities dry drilling may be necessitated by a lack of an adequate supply of water. Also during winter monthswet drilling may be very troublesome or impractical due to the formation of ice.

It has been proposed heretofore to use compressed air for the removal of dust and cuttings from dry-drilled holes. Compressed air is ordinarily available at drilling sites since it must be supplied for the operation of the pneumatic drills usually employed. It is piped to the bottom of the hole and blows the cuttings up to the'mouth of the hole and out into the atmosphere. 7 Whenever the compressed air is admitted to the hole a cloud of dust emerges from the mouth of the hole. This dust constitutes a menace to the health of the operators and an obstacle to the safe operation of the drilling machine. The present invention eliminates the dust hazard and accomplishes the continuous removal and disposal of rocl; dust and cuttings by compressed air.

The apparatus of the invention comprises essentially a combination of means to introduce compressed air into a drill hole, a hood surrounding the mouth of the hole to confine the dust and cuttings blown up out of the hole by the compressed air, and suction means to draw the air-borne cuttings through the hood and away from the mouth of the drill hole. A rock trap in the form of a chamber that is of large internal'cross-sectional area relative to thedrill hole and hood is mounted in close proximity to the hood and is connected thereto by a short length of conduit which is small in cross-sectional area relative to the trap. The larger pieces of rock and rock cuttings blown out the hole are collected in this trap before they can enter the suction device and either clog it or damage it. Advantageously, the air suction means is a venturi tube ejector which is operated by a stream of compressed air directed into its throat through a nozzle pipe mounted in the venturi tube a short distance up- FICe 2 stream from its throat. To insure complete elimination of any dust nuisance, a dust collecting chamber may be provided at the discharge of the venturi tube or other suction device. The dust collecting chamber comprises a series of closely spaced contactor plates, and a spray nozzle mounted upstream from them for delivering a film of water to their surfaces. Fine cuttings and rock dust discharged from the venturi impinge on the water film on the plates and thus collect in an aqueous slurry which is readily disposed of.

An advantageous embodiment of the invention is shown in the accompanying drawings, in which Fig. 1 is an elevation partly in section of the new apparatus for removing dust and cuttings from drill'holes Fig. 2 is a plan of the hood surrounding the mouth of the drill hole, taken substantially on the line 2-2 of Fig. 1;

Fig. 3 is an elevation in section of the venturi tube and the nozzle pipe that operates it; and

Fig. 4 is an elevation in section of the dust collecting chamber at the discharge end of the venturi tube.

As shown in Fig. l, the complete apparatus as installed for operation comprises some five main components arranged in the following order: a compressed air delivery pipe 5, a hood 6, a dust trap 7, a venturi ejector tube 8, and a dust collecting chamber 9. The compressed air delivery pipe 5 enters a drill hole 10 at its mouth and passes down to the bottom where the drill bit 11 mounted on a drill rod 12 and driven by drilling machine 13 is cutting through the earth. The stream of compressed air from the pipe 5 blows rock dust and cuttings up around the, drill rod 12 to the mouth of the drill hole, which opens into the interior of the hood 6. The amount of compressed air supplied should of course be sufiicient to blow all cuttings out of the hole continuously, as fast as they are produced by the drill bit. If a hollow drill pipe is used in place of the drill rod 12 to carry the drill bit 11, such drill pipe may be used also as the compressed air delivery pipe in place of the pipe 5.

The hood 6 is a conical enclosure surrounding the mouth of the drill hole and apertured by the provision of a slot 14 to enable the air pipe 5 and the drill rod 12 to enter the drill hole. A hollow stem 15 attached to the bottom of the hood 6 extends for a foot orso down into the upper end or mouth of the drill hole 10, to locate the hood properly with respect to the hole and to secure it inplace. However, the stem 15 is not essential to successful use of the apparatus-a hood without any the hood 6.; The conduit 16 connects with the inlet side of the trap 7 in off-center relation therewith, at a point near its bottom, and another horizontal conduit 17 (which leads away fromthe-upper portion of the dust trap and provides for connection through afiexible hose 18 with the venturi tube ejector 8) connects with the outlet side of the trap in ofi-center relation therewith, at a point near its top. The conduit 17 extends well into the upper portion of the dust trap 7, and its open inner end 19, which is situated inside the dust trap 7, is cut away at an angle of approximately 45". so that it faces awayfrom the interior of the trap chamber.

end of the conduit 16 where the latter opensinto the Dust and cuttings blown up the drill hole into hood 6 pass through the horizontal conduit 16 into the lower portion of dust trap chamber 7. Since the velocity of air movement from the hood is preferably high, some rather agrsdooo oft-center and no'n coa xial relationof the connections of tlrec'conduitsilfi'and:17-to the'trap insure that'such mate rial'does not simply pass through thctrap'. Thetrap may bet-emptied, when necessary, by lifting the hood stem "15 from the-hole-rand tilting the trap upwards so that "the trapped material falls out through the hood and hood stem. 7

The hose 18 is sufficiently long andfleXibleRto-permit locating the venturi ejector 8, "from which lthe fine ro'ek cuttings are discharged at a-convenieut distance'fromthe mouth of the drilllhole. The eiectorwomprisesa venturi tubeTSl having; a sha'rply constricted upstream portion leading'ito 'the throat of the tube and a gradually widened downstream portion leading away'from the throat. As best shown in Fig. 3, a nozzle pipe 20 enters through the sideof the ejector tubea short-distance upstream from its throat. The lower end of the noZZle pipe ZD isclosed-but it'is: provided with a nozzleorifice '21 in its side-walledjacent its-lower end. The nozzle orifice'issubstantially coaxial with the bore of the venturi tube 8 and is'aimed towards its throat. Compressed air at say' 90 pounds'per square. inch is introduced through the nozzle pipe'20 and passesithrough the orifice 21 to operate the venturitube 8 and create a suction which'draws' arstream of air borne cuttings from the mouth ofthe drill hole-through the hood Grand the dust trap'7. It is dcsirahleto provide the venturi. tube 8 with a lining of rubber 22 to minimize-wear dueztothe abrasive edect of the strearnof rock dust being blown through it at high velocity.

Preferab'ly the downstream side of the venturi'tube '8 discharges into the dust collection chamber '9. Awater spray nozzle 23 is mounted in the air-stream at the'discharge 'end'of the venturi tube-8, so as to'direct a spray of water into'the stream of dusty air toward a series of closely'zspaced contactor plates. The main'body portions 24 of'the contactor plates are arranged parallel 'to the direction of flow of the air discharge 'from'theventuri tube, but "each plate is provided with a battle portion '25 arranged'at a 'substantial angle, preferably 90, to the body portion. Each plate is arranged so that its bafiie portion blocks ottthe passage between it and a neighboring plate, therebyrequiring'theair stream'to' undergo a sharp change indirection as itemerges from "between the plates. The

getherwith'fine rock'cuttings and dust in the air'stream water spray delivered through the spray nozzle 2310- impinge on the contactorplates'and there unite to'form'a thinaqueous sluriywhich is discharged through the outinches venturi tube having an upstream internal diameter of three yttosansintemahthroattdiametor of one and seven-sixteenths niches in six inches, and then widening uniformly in eighteen inches to a downstream internal diameter of three inches. wall of the nozzle pipe of the venturi tubewas onequarter inch in diameterand one-quarter inch long, and compressed air was delivered to it at about 90 pounds per square-iiniihgau gepressureI I Among the important advantages as the new dust re moval apparatusis, itsasimplicity anddnergpensivesonstruction. It eliminatesdust Quite completely from the immediate vicinity of the drillhole, and yet is easily portable and requires little crud attention wliile in operalet 26 of the du's't collector. The 'contactor'plates'divitie 7 v the stream of dusty'air into'a series of narrow strips'and are continuously covered with a 'filrn'd'f water. Theythus assureth'at maximum effectiveness of contact between the water and 'the rock 'dustis achieved. While use o'f'th'e" dust collecting chamber'9 is not essential, iris-desirable tozimprove working conditions at'the drilling site. If the impingement chamber 9 is not employed, owing to the lack "of an adequate supply of water or-for other'reason, then careshould 'be taken to place the discharge end of venturi tube 8 fat-enough to the leeward or downwind side 'oi the drilling crewthat no dust'is blown'towards them.

Eminen'tly -successful 'operationof' the above-described embodiment-of thejnvention has 'been aclziieved usinga compressed air operated venturi rejector capable of "developing a partial vacuum equivalent to some "forty-five inches'of water. A'suction of this'magnitude wasobtained through a drill hole three inches 'diamet'erusing a tion. Use of the new apparatus intdrydrilling operations has led to increased drilling speeds, since the cuttings and dust maybe withdrawn continuously from the bottom of the drill hole, instead of only intermittently as was necessary under ifortnerpractice-to minimize the dust hazard when using i compressed air to l blow i out the cuttings; a

We claimzfi I Apparatus forthewembval of cuttings from" a drill-hole beingl dry-drilled in the earth comprising a *hood adapte'd to overlie and .enclose'fthe mouthof said i hole, said hood being apertured to permit passage therethrough of -a-drill ro'd extending substantially-axially into said drill hole, an airpipeextendirig through said hood to a point'adia-"l cent the bottom o'fisaiddlilPhOlQ 'l'l'lGflllS for introducing compressedaininto'said drill hole through saidairpi'peg thereby to filOWl'OClC dust and cuttings npto-and out'of the mouth of said hole', a rock trap mounted :in' close proximity to said hood, said rock trap comprising' a charm her of interual cross=sectionalarea that is 'largerelative to the cross-sectional area of the: drill "hole,*a conduit connecting the' hood withtlrelowerportion of the rocktrap, a venturiejectonhaving a throat of reduced cross sectionzil area relativedoits'inlet'and outlet ends, a flexible .conduitofsmallcrossasectionali area relative to said rock trap connecting tl're' inlet end .o fsaid ejector to thc,upper, portion :of'the .rock' trap, saidflexible' conduit being out of 'alignment'wi'ththe conduit connecting thehood'with thelower portion of the rock trap, a compressed air nozzle pipe communicating with'theinterior of said yentuiiejector upstream from and adjacent its throat, meanstor delivering compressed air through seiidhozzle pipe [into said venturi ejector,'wlterehy rock dust a'n'dlfine cuttings blown up the drill ih'olefby compressed .air delivered -;throug'h.the.air,pipe are drawnthrough saidfltrap andar e dischargeddhroug'hlsaid .venturi ejector whereas relatively large cuttings and rock .withdrawnrfrom the drill'hole in the airstream are. collected in said. roclctrap, '8-'6l' l$5 V of closely .spaced eontactorplates mountedin .the-.d.ischarge, of .said suction ejector, said iplates :each having a body portion arranged parallel to the direction :of-

of .air dischargedliroxn the suctiondevioejand phallic, portionzarranged at a substantial angle to;said-.body;portion, a spray nozzlemounted in the-discharge fromsaiti -venturi ,ejector upstream from .rhe body portion of -;said

plates, .and .means .for .delivering water :tosaid 51102216, 3 whereby water sprayed: from said nozzle; impinges-on: said 1 plates and .forms thereon a filmofwvater in which-fine cuttings drawnirom the drill hole and [discharged from :tthe .suction .device I are collected.

,,neg ienc scidaamnesi a this, patent -umr-no snares PATENTS 1,981,570 Price novxzoitsaa 2,144,586 Kelley -s .Ja n. 17.15239, 2,182,165 Smith -.r; nc. .5,.1939 2,329,33 Brailey S t.14,1943 2,579,282

The orifice 21 in the s

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