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BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to an apparatus and ~ethod for efficiently transporting a slurry and, more specifically, relates to such apparatus and method which is adapted to employ pressurized air as means for disaggregating and propelling the slurry.
2. Description of -the Prior Art In connection with the transport of slurries such 10 as might be encountered in respect of mine tailings, it has been known to use various means of efecting such transport.
The specific system which wi11 perform effectively in such an environment is, in part, dependent upon the moisture content, density, and relative sizes of the aggregate or solid material contained within the slurry.
With respect to systems employed in transpor-t of concre~e, it has been known to utilize compressed air for disaggre~ation following use of a concrete pump for propulsion.
With respect to relatively dry materials, it has been known to employ compressed air for propulsion.
As min~ tailings tend to involve a relatively dense, aqueous mineral slurry which may have the density on the order of 110 to 140 lb/ft3 and contain about 42%-48% water by volume and the handling of large volumes of the slurry in an efficient manner are generally required, there remains a need-for improved apparatus and methods for dis~ggregation and transport of such slurries.
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SUMMARY OF THE INVENTION
The present invention has mat the above-clescri~ed need by providing an efficient means of dIsa~gregat~ng and transporting slurries including relatively dense, aqueous mineral-containing slurri,es.
In a preferred em~odiment of the inVention an auger having a variable pitch cooperates with first conduit means which are provided with inlet means to receive and initiate transport of ~he slurry. First air supply means provide air at relatively high pressure which impinges on the slurry, preferably downstream of the-auger means and ser,ves to dis~
aggregate the slurry. Second conduit means receive the slurry from the first conduit means where the slurry is subjected to air at relatively low pressure and high volume from second air supply means. This serves to propel the slurry. For certain installations, third conduit means which have sections diverging generally downstream may receive the sluxry from the second conduit means.
In the method of the present invention the slurry is moved through first conduit means wherein i,t ;`s subjected pc/ ~
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, to disaggregation at a first pressure and is subsequently ¦ ~:
subjected ~o propulsion at a second pressure with the second pressure preferably being at a lower level th~n the first pressure.
i It is an object of the present invention to provide efficient apparatus and associated methods for the transport of slurriesO
It is another object of the invention to provide , such apparatus and methods which provide means for disaggrega-tion of the slurry during transport.
i It is another object of the present invention to j employ air at different pressures for the disaggre,gation and ,j the transport functions.
i , . ., I It is a further object of the invention to provide I5 ', mechanical transport means which initiate transport of the slurry through the system.
I It is yet another object of the present invention t to provide such apparatus and methods which are adapted to ~ handle relatively dense, aqueous-mineral slurries such as 2Q "~ those which would be encountered in mine tailings. ~, ,~ BRIEF DESCRIPTION OF T~E DR~WINGS ~ -_ ¦ Figure 1 is a partially schematic cross sectional jl illustration of a form of apparatus usable in the present 'i invention.
¦I Figure 2 is a cross sectional illustration of the j, free end of the auger shaft taken through II-II of Figure 1.
Figure 3 is a cross sectional illustration of a portion of the first conduit means taXen through III-III of ¦ ~v~
Figure 1.
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. DESCF~IPTION OF THE PREFERRED EMBODIME:NTS .. :, I! Referring now, more speciically to Figure 1, ! there is seen elongated first conduit means 2 which has an I inlet 4 through which the slurry, such as a relatively dense I aqueous-mineral slurry of the type experienced with mine ' tailings would be introduced. The arrows illustrated within i the first conduit ~eans show the direction of flow of the slurry through the first conduit means. Disposed within .
I, the chamber 6 defined by the first conduit means 2 is an ¦ :
1' auger shaft 8 which has an axial bore 10 through which dis-aggregating air will be passed in a fashion to be described Il hereinafter~ A helical vane 14 of varying pitch is secured j to the auger shaft 8 and adapted to rotate therewith.
Il The auger shaft 8 terminates in a conical portion 1¦ 16 which, as is shown in Figures 1 and 2, contains a plurality ¦l of air discharge openings 20, 22, 23 which are in communication il with bore 10. This permits discharge of high-pressure air p into the annular zone defined by the exterior o~ conical ¦¦ section 16 and conical portion 18 of the first conduit means 2.
~0 j The high-pressure air emerging from openings 20, 22, 23 contacts ~ ¦I the moving slurry in this annular zone 24 and effects a ¦ ¦I disaggregation action on the slurry which fragments the slurry J li into relatively small globules. The disaggregated slurry then passes through pipe 25 of first conduit means 2 into the j second conduit means 32.
In operation of the portion of the apparatus described hereinbefore, a sui~able power source such as an electric motor , ~' ;
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~6 effects rotation of an output shaft 27 which is subjected to .:
speed reducing action of gear box 28 with the resultant rotary ; motion being experienced in output shaft 29 which serves to Il rotate auger shaft 8. A suitable source of compressed air ¦~ such as compressor 30 passes through pipe 31 and through a suitable swivel connection (not shown) results in introduction of the pressurized air into bore 10 of shaft 8 from which it I emerges at openings 20, 22, 23. While for simplicity of I ¦ illustration, three such discharge openings 20, 22, 23 have o l! been illustrated, it will be appreciated that any number may be employed.
¦1 As a result of the varying pitch of vane 14, it will ¦, be appreciated that the auger will tend to move the slurry ~e.~ 1 9~ .
; more ~1c ~ in the region of the vane 14 having a higher 111 pitch, adjacent to inlet 4 -than in the region downstream ; tharefrom. This sort of arrangement is found to be advantageous j¦ in order to facilitate efficient transport of the slurry -~through the first conduit means 2 as this tends to result in jl a higher percentage of the volume between adjacent vane portions ¦ 1 being filled with slurry and a reduced amount of air contained j' therein.
Referring now to Figures 1 and 3, an additional J ¦ feature which contributes to efficient flow and a high ¦ percentage of the volume betweem adjacent vane portions ¦ being filled with slurry will now be considered. This resists ¦ undesired backflow of air to the inlet 4. The generally ; cylindric:l ownstream sector of the first oonduit ~ean~ 2 I ~
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`is provided with a number of radially outwardly projeeting !~ hollow recirculating tubes 19. In the form shown, th~
' recirculating tu~es 19 are of genesally V-shaped eross . , I sectional configuration and are in commw~ication with chamber 1 6. They are circumferentially spaced from each other and generally parallel to the axis of shaft 8. In a preferred embodiment, each of the recireulating tubes, will have a height considered in a radial direction of about 5 to 10 ~ percent of the diameter of the cylindrical sector o the l first conduit means 2 with which it is associated and a width of about 15 to 20 percent of such first conduit means diameter.
j As it is desired to maintain the auger at as high a percentage ¦ of filling as possible in order to develop a pressure within l' the slurry and overcome any back pressure within the first 1 conduit means 2, as well as contributing to efficient and rapid movement of a large volume of slurry, recirculating tubes 19 provide localized zones to receive additional slurry. This , serves to resist undesired, potentially blocking buildup of ! slurry in the first conduit means 2.
20\ 1 Referring now to the secGnd conduit means 32 in \ greater detail it will be noted that in the form shown it is ,` of generally Y-shaped configuration having a pair of inlet pipes 33, 34 which may advantageously be substantially ~ \~l cylindrical for receipt of propulsion air to move the slurry 25 1 along. The propulsion air is preferably provided at a lower , pressure than the air which passes through bore 10 of auger ¦I shaft 8 and is prcferably provided in larger volumes than the air which passes through bore 10. In the preferred "' .
~ ~ r7 2 i~ 1 Q~bodiment of the invention the air enteriny through pipes 33, 34 will preferably be at a pressure of about 10. to 15 psi and the ai.r entering through bore 10 will preferably be at a pressure of about 35 to 115 psi. Also, it is preferred that the total volume of air introduced through pipes 33, 34 be about S00 to 1500 cfm. It is noted that in the form illustrated the pipes 33, 34 are disposed on opposite sides.
of pipe 25 which in turn communicates with second conduit means 32 throuyh opening 35. The slurry entering through opening 35 will meet the second air supply entering through.
pipes 33, 34 in chamber 36 which.contains the vertex of second conduit means. The high-volume, low~pressure air will serve to cause the slurry to be propelled through. discharge opening 38 in second conduit means. 32.
Air supplied to tubes 33, 34 may advantageously be supplied by a suitably sized blower (not shown~ connected to pipes 33, 34 by suitable ducting or, may be provided directly in the pipes 33, 34. Also, if desired, additional pipes may be employed to provide the same volume or a greater volume of propulsion air. In general, while the system would function with a single pipe, it is preferred to provide at least two, : . In the form illustrated, a third conduit means consisting of a series of pipes 40, 42, 44 wh.ich define a series of diverging passageways sequentially receive the slurry discharged from discharge outlet 38. This serves to facilitate efficient flow of the slurry emerging from the second conduit means 32.
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i! ( (`i f~; 7 1 ¦' It will be appreciated that the method of the present . - .
: invention in its broader aspects involves moving the slurry li through a first conduit means wherein it is subjected to l~ disaggregation at a first pressure and subsequently subjecting.
¦ the slurry to propulsion under the influence of air at a second pressure which is less than the pressure of the dis-" aggregation air, but is supplied in greater volume.
¦ While in general, use in connection with dense, ..
1 aqueous mineral slurries such as those experienced with mine ¦I tailings is contemplated by the present invention and such .¦' slurries will typically have a specific gravity of about 1.8 . to 2.3. It will be appreciated that the method and apparatus .~
j may advantageously be employed with other types of sl~rries.
¦, It will be appreciated, therefore, that the present invention provides an apparatus and method for effecting efficient disaggregation and transport of slurries through use . .
of a combination of high pressure disaggregation air and low-pressure, high-volume propulsion air, with the disaggrega-~ iI tion preferably occuring prior to the propulsion air intro- ~
20 . Il duction. In addition, through the use of unique auger means . ..
\ ,. having variable pitch and an axial bore, in the preferred embodiment, initial slurry propulsion and disaggregation may !, be accomplished within the first conduit means.
1) While reference has been made herein to first, I second and third conduit means, it will be appreciated that ¦¦ this description has been provided in the interest of disclos-i ing the best mode known to applicant oi practicing the invCntiOn and in terms of physiaal oonstr~ction as distinguished ¦
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.-, .1 . .. ~, ¦ from function, the components may be made in a different ; I' way and assembled to accomplish the functionally equivalent ¦ results.
' Whereas particular embodiments of the invention S 1I have been described above for purposes of illustration, it ! will be appreciated by those skilled in the art that numerous - variations of the details may be made without departing from the invention as described in the appended claims.
We claim.
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