US1556250A - Process of and apparatus for use in drying ores, concentrates, and other granular materials - Google Patents

Description

G. RlGG ET AL PROCESS 0F AND APPARATUS FOR USE IN' DRYING ORES, CONCENTRATES,

` AND OTHER GRANULAR MATERIALS EN 5M Oa. 6, 1925. v 1,556,250

G. RIG@ E1- Al. PROCESS 0F AND APPARATUS FOR-USE IN DRYING ORES, CONCENTRATES,

AND OTHER GRANULAR MATERIALS Filed July 11, 1922 3 Sheets-Sheet 2 on. e, 1925. 1,556,250

G. RIGG ET AL .PROCESS OFAND APPARATUS FOR Use: IN DRYING GRES, CONCENTRATES,

AND OTHER GRANULAR MATERIALS Filed Jul-y 1l. v1922 3 Sheets-Sheet s Passed oa. e, 1925..

1li-UNITED STATES- 1,sss,zso

PATENT oFFlca.

GILBBT MELBOURNE, VICTORIA, AND il'. MO'BBIDE, OF BROKEN I HILL, NEW SOUTH WALES, AUSTRALIA.

PROCESS Ol' AIND APPARATUS-FOR USE`INDRYING DRES, CONCENTRATES, AND OTHER GRANULAR MATERIALS.

. Appuauon mea July 11, 1922. serial No. 574,215.

To all twhom t may' concern: c

Be it known that GILBERT Rice, of care of 'The Broken Hill Associated Proprietary Limited, of Collins House, S60-366 Collins Street, Melbourne, in the State lof Victoria, and WILLIAM JOHN Mc- Bnmn, of care of The Broken Hill South ,Limited of Broken Hill, innthe State of New South Wales, both in .the Commonwealth of Australia, metallurgists,,hav'e invented certain new and useful Improve- 'ments in Processes of and Apparatus vfor Use in Drying Orcs, Concentrates, and Other Granular Materials; and we do hereby declare the following to be a full, clear, and exact description of the invention, -such as will enable others skilled in the art to which s l'it appertainsto make and use the same.

This invention relates toa process of Aand apparatus for use '1n drying. ores, concen-L trates, and other granular materials, and 'refers moreespecially to processeswherein a hotblaster draught of heated vair,- or vof.a -to carry of moisture from the materials being dried.

"The invention may beemployed for drying' or4v dehydrating different lkindsV ofgranular material and .throughout the following-f. specification, v, wherever 'the yterm oresfis'used'it is to -be understood as meaning and-including other granular materials.' The'object of the invention is to .provide v Ameans whereby granular material inl a damp "form can be eiiiciently and expeditiously dried or dehydrated in an economical and' convenient manner.

We accomplish the object of this inventionby providing a process. of drying ores -which consists of forming a layer of thewet or damp material on a porous bed, drawing `or forcing hot gases through the said layer and porous bed, drawing oli' the moisture with the hbt gases, and finally drawing'the dried or dehydrated material through the said porous bed.

In practice, we provide a layer of the material to'be dried, supported'or-imposed on a porous bed through which hot gases Smelters are drawn. The bed is of such a nature dry. The interstices of the said porousbed are such as to offer' a certain resistance to the passage of the gases, thus assisting to maintain even conditions of draught through the The process may be operated continuously or intermittently. When operating continuously, the ore may be caused to progress on aperforated bed. l The apparatus Aforgiving effect to this invention may partake of a number of different modiication and, briefly comprises a porous bed in communication with a cham- -ber connected toan exhaust fan or blower. This' porous bed is formed of a screen on the upper surface of which, or between two lay- 'ers thereof is provided a layer ofspherical or rounded bodies of a dimension vwhich will aiford interstices through which the ore will pass more' or less freely when' dry. Means are-provided for directing heated air for gas to the'space adjacent Ato the porous I 75.

type of s Invention.

Figure 1 is a longitudinal section of one' apparatus giving effect to this "Io v Figure 2 is a transverse sectional elevation `of Fig. 1.

Figure 3 is a perforated bed. A

'Figure 4 is a vertical section of a modied -form of the apparatus for giving effect to this invention. Figure 5 is a detailed sectional view of the perforated bed used in Figure 4.

Figure 6 is a vertical section of another modified -form of apparatus for giving effect t0 this invention.

detailed sectional view of the ratus in which the perforated bed is horiyzontal. 'The apparatus consists of achamber A having a lire box B arranged at one end with ya communicating flue B for delivering hot air and gases into the top of the chamber A. Extending longitudinally along .the chamber A is a perforated screen C above which is adapted to move a series ofv push conveyors D. These conveyors D are adapted to move the damp or wet ore which is fed on to the screen C through the chute E intermittentl forward so that an even layer of the said damp ore is spread over the screen C. This screen C is formed of perforated metal or woven wire and upon its 'surface is provided a bed of rounded balls, pebbles, or other coarse material. This perforated bed is shown more particularly 1n Figure 3 consisting of, kthe perforated metal screen C u on which is superimposed pebbles or balls uponwhich the layer of ore is imposed.

This layer of spherical or rounded bodies may be balls of burnt clay, rounded silica grains or other pebbles, iron balls orA other suitable materials for the purposeof forming a porous bed for the ore. It is essential that the balls, pebbles or other material employed for forming this bed havel such dimensions and shape that interstices are provided through which the dried ore I'oan'pasa This layer of spheric-al or rounded bodies having a certain amount of mobility or restricted movement, any tendency to chokev or clog is avoided.

In the case of ore concentrates adapted to pass through 40 mesh screen, we have found that balls or pebbles ranging from oneeighth of an inch to onequarter of an inch diameter and forming a layer of about one inch in thickness will well answer the urpose. The screen must be coarse enoug to allow the dried ore particles to ass throu h, and fine enough to retain the alls, pebb es.

,or the like.

Beneath the-screen C the chamber A is formed into areceiving box A for the dried .ore formed with an inclined back plate A2 whereby the material is 4delivered into the discharge chutes F. These chutes F are provided with control gates or doors F. Leading from this lower portion A of the chamber A is an exhaust G which is in communication with a fan or blower or other draught inducing means, whereby a continuous suction is maintained through the perforated bed drawing the hot gases down therethrough. At the vrear end of the chamber A, a discharge chute H (having a control door H) is provided leading from that portion of the chamber above the perforated bed whereby any lumps or coarse material which do not pass through the perforated bed are withdrawn.

'the chamber A above 'nace or other source of hot ain In practice, the ore is fed down continuously on to the perforated bed, and is conveyedl therealongzby means of the push conveyors D; at the same time, a current of hot dry air and gases is directed from the furnace B through the flue B into the space of the surface of the layer of, damp ore. f 'V As a certain proportion ofthe moisture is removed, the particles of ore tend to adhere together to a lesser degree and to tricklethrough the interstices of the perforated bed, the removal ofthe moisture `is thus accelerated bl the movement of an increased quantity o hot air and gases through the said bed. Any tendency to -choke'on clog las otherwise the moisture from the ,upper layersfiivilllbe carried down and condensed on thelow'erlayers so 'as to interfere with the porosity of the bed and. the satisfactory inductionof the air and hot gases. therethrough which is essential to the working of the process.`

'is avoided by the restrlcted movement of Ingfthe apparatus illustrated inFigures 4 and'5, the perforated bed is in the 'forni of a quasifcylmdrical screen preferably slight- 1y tapering toform a truncated cone, Re-

:ferr-ing" to these figures, ,A is an enclosed chamber within. which rotates a screen C* mounted u ona central. shaft K'. This-central shaft carries a'series of radial arms K which .support the screen Cx which is preferably formedas shown in Figure 5,

that isto' say, comprising an inner perforated screen C" andan outer perforated screen C, the space between accommodating pebbles, balls 'or`other like rounded material C between the interstices of which the dried material is caused to pass. The chamber A is formed with an extension' A3 into which delivers a iue B" leading from a furand gases. Within this extension A3 is an internal sleeve J vinto Vwhich the ore is fed by the chute E from the conveyor belt E (or other source of supply) to which a hood E? is attached for excluding the draught. A screw conveyor J delivers the damp or wet ore into the interior of the screen C". The other end of the chamber A is formed with a diaphragm through which the end of the screen Cc projects, more or less dividing the chamber A into twoparts so that the fine dried material passing through the screen is delivered into the portion A fromwhich it is withdrawn, whilst any lumps or coarsel material which do not pass through the screen are delivered through the chute H.

The chamber A is in communication with a fan, blower or other exhausting device through the opening G.

In practice, the damp or wet ore is fed down through the chute E from the conveyor E into the'interlial cylinder J where it is conveyed bythe screw feed J into the interior of the rotating screen C". The wet ore is thrown out in a layer upon the inside ofthe screen C". The radial arms K on the shaft K serve to agitate and break up any lumps and evenlydistribute the said ore upon the said screen.

The hot air and gases coming in through the iue B are delivered on the surface of the llayer of -ore and drawn through the screen to the exhaust outlet G. As the screen rotates, the balls, ebbles or the like of which the porous be is composed are subject to a certain amount of restricted movement, thus avoiding any tendency to A choke or clog. As the moisture is removed and the material becomes dried,-it is carried through th screens and between the interstices of the balls, pebbles or other like material between the screens C2 and C3.

The dried ore settles down into the lower portion A of the chamber A and may be withdrawn from time to time, whilst anyoversize or coarse lumps or foreign matterL which will not pass through the screen are withdrawn through the chute HQ Referring to F1gure- 6, the chamber A. is provided with a horizontal screen C which 1s formed as illustrated in Fig. 1, that is to say, with alayer of pebbles, balls and such likematerial on the surface thereof. Surrounding this screen C is an annular chamber L communicating with the chamber, A above the surface of the screen `C throu h the ports L. The chamber .A above t e screen C )is provided with a horizontal diaphragm A. Above the screen C is mounted. a vertical shaft M having a series of rotating blades or rabbles D mounted upon arms D. Above the chamber A is a feed chute E into which the ore is delivered from the con# veyor E and within the lower the chamber :A is provided an ex G communicating with a fan, blower or other exhausting device. The draw-off F for the 'ore is arranged vat the bottom of the chamber A anda similar draw-off H for the coarser material or lumps which do not pass through the screen C. The operation of this machine is the same as that already described with regad-.t the other views.

We claim'z- 1. process for drying ores and other dried or dehydrated material throug portion of aust pipe granular materials consisting 'of forming a la er of the material on a porous bed, inducing a current of hot gases through the saidlayer andporousbed, drawingof the moisture with the hot gases, and drawing the dried or dehydrated material throughthe said porous bed.

2. Aprocess for drying ores. and other granular materials consisting of forming a layer of the material on a porous bed, inducing a current of hot gases through the said layer'and porous bed, agitating or stirv Vring the layer of'material on the said por ous bed, drawing off the moisture with the hot gases, and drawing the dried or dehyldrted material through the vsaid -porous e I 3. A process for dryi g ores and other granularmaterials consimgof forming a' layer of thematerial on a porous bed, inducing a current of hot gases through the said layer and porous bed, causing the said material to progressalong the surface of the said porous bed,l drawing off the moisture with the hot gases, and drawin te 90 said .porous bed. l

4. An apparatus for drying ores and other granular materials, consisting of a porous bed upon which a layer of the wet or damp` materialv is imposed and through' -which hot gases l arel drawn, characterized by the fact that the bed is of such a nature .that the 'ore is 'retained upon its surface whilst damp but asses through it when 10' dried or dehydrated. 5. An apparatus for drying ores and other granular materials wherein a layer of the damp or wet material is imposed upon the surface of the porous bed through which hot gases are'drawn characterized by the fact that the said be is formed o f'at least one perforated screen and a layer of pebbles, Aballs orother rounded materials,the intersticesbetween which are such as to offer 11 certain resistance tothe passage of the gases and retaining. the ore on the screen whilst still dam-p, but permitting of the passage of the ore therethrough when dried or dehyl drated.

6. Apparatus for drying ores and vother granular materials consisting of a chamber having la rotating screen mounted therein, means for feeding the wet or damp material 'into the interiorof the said Screen, means for sup lying hot gases into the interior of the said) screen and means for drawing off,-Z through the said screen the said hot gases,'"'f and means for withdrawing the dried ore v '.from the chamber passing through the said 125 perforated screen.

, 7. Apparatus for/drying ores and other granular materials comprising a chamber having a rotating screen mounted therein,

the wet or damp material lbeing fed into the 13 interior of the saidsoreen and hot gas being damp or Wet materialis` retained on the drawn through the said screen, characterized s'oreen Whilst dry material is permitted to by the fact that the said rotating screen conpass therethrough. 10 sists ofan inner screen and an outer screen In testimony that we claim the foregoing 5 the space between which is filled with balls, as our invention, We have Si ed our names.

pebbles, or other rounded materiale the in- GILB RT RIGG. terstices between which are such as that WM. J. MCBRIDE.

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