US1466382A - Ore-roasting furnace - Google Patents

Description

Aug. 28,' 1923.

lR.D,PH E ORE ROASTING FURNACE 5 sheets-sheet s' Filed A'pril A13 1921 nvVENTOR HMf/L 'vyag ATTORNEYS Patented Ang.. 2%, E923..

man ,stares intatta raar raies'.

manna" D. rma, or san rimncraco, cnrrronmn..

oRn-noesrrno remmen.

fllppliceton led April 13, 1 921. Serial No; 460,973.

Be it knownthat I, Ronnn'r D. PIKE, a citizen of the United States, residing at the 4'city and countyof' San Francisco and State 5 of "Ca1ifornia, have invented-certain new and useful-Improvements in Ore-Roasting fication. l

Furnaces, of which .thefollowing is a speci- The present invention relates to an improved apparatus for the calcination of. car bonate rocks, such for instance as' calcite and magnesite, orjthose where the reaction is strongly hea-t absorbing, the object of Vthe invention being to produce 'an apparatus l5 wherein the fuel necessarily required forv the calcinat'ionvof the ore may be applied in such'a manner that' the heat of combustion shall be applied uniformly over a large area of the charge under treatment,and in 0 such a manner that no part of the furnacev shall become locally overheated. This ob ject is accomplishedby the employment of a plurality of vertically disposed lire boxes, into which the f uel is ejected in a Asubstan- I. tially vertical direction, either from the top'or bottom, and burned'throughout the length of the lire boxes and relatively'close to the furnace, the products of combustion andthe radiant energy of the ame passing For anunderstanding of. the invention,

. reference should be had to the accompanyferred embodiment of my invention, where- 1n Figure 1 is a part broken vertical sectional view of the improved mechanical roasting furnace, illustrating one form of means for the introduction of broken coal or pulverulent fuel mixture over 'one of the hearthsv of the furnace. l

rFigure 2 is a broken vertical sectional ing sheets of drawings illustrating the pre- View disclosing the means for feeding the fuel medium over Ythe hearth of the furnace from the outside of the furnace shel1.'

Figure 3 is, a broken 'vertical lsectional view illustrative of Ine'ans for thev feeding i of the fuel'medium to the hearth of the furnace from the inside of thevfurnace shell.

Figurell is a broken detail vertical 4sectlonal view-of the furnaceI taken on the sec- ,tional line XQK Figure 5 of 'the drawings and viewed inthe direction of the ar-, rows, said view illustrating the means for preventing `the passage of lair upwardly from the upper cooling hearth, while permitting, the material under treatment to pass downwardly thereon. v

' Figure 5 is a horizontal sectional view of the furnace taken on line X-X Figure 1 of the' drawings and-viewed 'in the direction of the arrows.

Figure 6 is a broken detail horizontal sectional 'view taken'on line.- Y--Y, Figure .1

of the drawings,and viewed in the direction of the arrows, said view illustrating the interior construction of the rabble arms and the connection ofthe same with the central rotating column 0f the furnace structure.

. In thedrawings, Figure 1 thereof, the u numeral lis used to designate the outer shell of a stationary furnace, which is supported in the present case by the uprights 2, the said shell being interiorly provided with a refractory lining 3. Within the furnace shell is arranged -a series of spaced horizontally disposed hearths, of which series the hearths 4 are those on which the material movesoutwardl dropping therefrom onto the hearth immediately below through the cutouts 5 provided therein adjacent the inner refractory lining of the shell l. lThev hearths 6 ofthe series are those on which the material moves inwardly or toward the central rotating -column of the furnace structure, the material dropping therefrom `onto-the hearth next below through the annular ring opening 7 thereof adjacent the wall ofthe central rotating column ofthe furnace structure. The material' under treatment thus passes'through the apparatus in a zig-zag path of travel` from the uppermost hearth until the lowermost cooling hearth 6a is reached. These hearths surround a vertically disposed central rotatingcolumn, which in the present case is composed of two spaced concentric members Sand 9, so disposed relative to each other as to provide or leave an annular space 10 therebetween. Rotation may be imparted to the central vertical column of the furnace structure by any suitable means, as for instance through the medium of the bevel gear- 11, secured to the lower extended portion 8 ofthe vertical column meshing with a pinion A12, which is driven by any suitable source of outside power.

By means of a blower, not shown, airv under pressure is introduced through the air sup-ply pipe 14 into the central hollow shaft through the running joint 14, the said nair passing outwardly in several streams through the later-ally extended passages or passageways 15 of the central. column, which communicate with one of the passageways ofthe rabble arms 16. rl`hese rabble arms are formed hollow and subdivided interiorly by means of a centrally disposed partition' Wall into two parallel longitudinally disposed communicating passageways a and ai. The air discharging from the central column through the passages 15 enters the passageway a of the rabble arms, flowing throughout the length thereof and passing into the companion parallel passageway a through the end connected passage c of the arms` and escapes fro-m' the said arms through outlet openings 15 int-o the annular space 10 of theJ central column, Figure 6 ofthe drawings. The air discharging from thev rabble armsA into the annular space l0 of the central column moves upwardly and escapes'therefrom into the pipe 18 thro-ugh a running joint 17. The p-ipe 18 is a bent stationary one, 'and Vat itslower end coni-- munioates with the interior of the furnace structure immediately above' the coo-ling hearth 6a, so that the air discharging from -the furnace structure is returned therein over the said lowermost cooling hearth. Each rabble arm is attached in any suitable manner to the centra-l rotating column so as to place the parallel passages a and a' thereof in communication respectively with the air outlet and inlet passages 15 and 15 thereof. and each carries a series of depend'- so that the material under treat-ment moves downwardly through the furnace in a zig- Zag path of travel from top to bottom, 'lt

will be understood that there is a` series ofv rabble arms associated with each hearth of the furnace.

The charge of material to be treated and fed to the apparatus is in more or' less of Y a pulverulent form, and is fed to the furraeaaea nace in a regular continuous 'stream through the medium of anyV suitable vrform of auto maticv feeder, not shown, while the products of combustion and calcination leave the top of the furnace through any suitable form of outletstaek, which is not shown in the drawqually spacedav around vthe furnace and at the outside thereof vare three vertically disposed lireY boxes 25, each of said boxes being provided with a burner 2G for the burning of pulverized coal or atomized 'oil` the said fire boxes being interiorly provided with a refractory lining, and each provided with a series of clean-out and inspect-ion doors 261. The products of combustion from these tire boxes pass into the furnaci` over eac-h of three hearths, at three points,

through horizontally disposed ports 2T. the lowermost of these three hearths being the fourth hearth from the bottom of the furnace, Figure 1 Aof the drawings.

Any slag or dust which collects wit-hin the bottom of the' fire boxes from the burning fuel is removed periodically through the clean-out doo-r 28, ,situated adjacent the y bottom of each lire box.. Heated air is drawn from the furnace over the see-ond '4 from the bottom of the furnace through the eut-out outlet V5 'thereof by extending these cut-outs downwardly through the fireiclay chute .296, which is provided at its lower portion witha side bottom discharge 30 toward the center oflthe furnace, Figure- 4 of the drawings. The discharge 30 is sealed by the natural slope -of the material which accumulates on the hearth 6 immediately below the said hearth 4; while the air for cooling and combustion enters the furnace over the cooling hearth G, and may be taken 'in whole or part from the pipe 1S. rlhe bottom discharge 3l of the furnace is sealed against. the passage of air by any suitable means, notshown.`

The air which is preferably taken from the bent stationary pipe 1S in passing over the calcined material lying on the bottoni or cooling hearth 6a of thefurnace cools it, thence Hows o-utwardly from the furnace through the laterally disposed passageway 29 and is returned into the fire boxes 25, and thence with the products of combustion passing baclcinto the furnace. the draft' for inducingthe. necessary motion of air being .furnished by a stack, qnot shown.v Ordinarily twenty-tive per cent more air is admitted through the pipe 18overthe bottom or cooling hearth 6i* of the vfurnace than 1s theoretically required for the'v combustion of all the fuel.

Y Y Each fire box is preferably provided with under treatment, the same is broken lso thatA practically all willpass a one-eighth inch screen, and is'fed in a continuous regulatable stream by any suitable form of automatic feeder into a small hopper 34, which discharges the .same into the horizontally disposed feed pipe ;*Figures 1 and 2 of the drawings. -This'ppe passes 'through the furnaceshell and terminates in a flattened 'nozzle 35a,- the rear or outside end of the pipe being closed and furnished with a small centrally:` disposed high pressure air pipe 36.l The pipe 35 is provided in its side with an air inlet opening 37, which .may be controlled in any'suitable manner to regulate'the inlet ofair into the pipe The i high pressure air entering through the pipe 36 induces more air to enter through the inlet 37A than otherwise would take place, :ind-

the full quantity of this air fiowing',r under pressure sweeps the broken coal or fuel inediu'in discharging into the`pipe 35 onto its associated hearthwithin the furnace, Where it is intermixed with the charge under treatment by means of the rabblearms. L If so -desired,.a series of Vthese feeders for deliv ering broken coal or fuel medium into the furnace may be installed at one or several 'points over any one of the hearths of 'the furnace, and it will be understood that either broken coal or coke may be used as the fuel medium, and further be it understood that any suitable form of mechanical means other than the one described nay be employe-d or utilized for introducing the fuel medium into the furnace through the outside shell and onto the material for treatment. i

n By Figure 3 lof the'dr'awings, an alternative form of means for'introducing the fuel to be intel-mixed with the material under treatment is illustrated, the same comprising a rot-ating hopper 38 into which 'the fuel is supplied from a chute 39. VVithiu the hopper 38 is arranged or located a non-ro- .'tating verticallv adjustable conical plug which is capable of being raised or lowered b y means of a rackl and pinion 41. The hopper 38 is connected to a pipe 42 which .is extended into the vertically disposed rotating column of the furnace, the lower end of the said pipe screwing into a-casting 43 integral with the central rotating column and connects through the medium of the sloping passages 44 with the interior of the furnace over one of the hearths. AHigh pressure air is introduced into the passages 47 of the casting 43 by means ofthe air inlet 'pipe 45, the passagesll connecting with the interior of the vfurnace immediately below the passages 44.- By this arrangement, the coal or fuel medium deliveredinto the hopper 38 flows downwardly throughl the pipel 4t2-into thepassages A44 and is' blown into the 'furnace over the hearths thereof for mixture` with the materialunder treatment by means ofthe vhigh pressure air delivered into the-'passages-{l' fromv the air supply pipe45. vThis form of introducing the fuel medium' into the `furnace and onto `the hearths thereof,` is fully set forth and described in my co-pending application Serial No. 427,466,` for. improvedA continuous method and apparatus forv 'calcining and` clinkering-magnesite., to which reference is hereby made. l

In the use of the described apparatus, and under the construction thereof, I have found from practical experimentsV that about one half of the -fuel required for the'calcination of the ore charge is burnedin. lthe fire boxes proper and the balance introduced into the furnace and. intermixed with the ore charge through the auxiliary lfuel sup. ply means for delivering the same onto the hearvths within the furnace.- By thus reducing the amount of fuel to be kburned in the jli're boxesfthe wear and tear on the furnace brickwork is reduced materially and the life of thev furnace prolonged, While the radiation losses are reduced and-the'broken fuel which is burned in the furnace is consumed in such a manner. as to directly and eii= ciently transfer its heat to the action of calcination. This fuel delivered Within the furnace and onto the hearths therein for intermixing With the-.ore charge -isiignited by4 the hot ases of the furnace and by the flame injected into the furnace from the fire boxes. v

If coke, braize or pulverized coke be used instead of broken coal, the same may if de- 'sired vbe mixed with the ore charge before it is fed to the furnace instead vof being` delivered overone of the combustion hearths of the'furnace for intermixing with the orc charge. This. however, cannot be done with the coal, because the volatile constituents would be volatilized on the upper hearths where the Atemperature would not'be high enough to ignite them and they would be lost up the stack.v

In the operation of the appartus', the material to be treated as fedinto the apparatus is received on the uppermost hearth of the series, andby the movement of th'e rabble arms is propelled by the teeth thereof until the outlet passageway of the said l hearth is reached 'and is discharged on to the succeeding hearth, beingl propelled by the teeth4 of the rabble arms associated With said hearth thereover until` the outlet of said hearth is reached when the -material falls on to the succeeding hearth, and so on' successively throughout the furnace, the

material being moved or propelled in a zigzag. path of travel. As the material moves over the hearths Within the combustion zone of the apparatus or those hearths associated with the fireboxes of` the apparatus',`-the.

material is subjected to the action of the flames ejected from the re boxes onto the combustion hearths, and at the same time the fuel medium ejected into the apparatus by intermingling with the ere charge is subjected to the action of the said flames,

' and equally so, of the hot gasses passing up- Wardly through the furnace, Which causes the ignition of such fuel medium. Theair for the coolingof the rabble armstravels vcalcination of the .through the apparatus, and such calcination 'forwardly and backivardly through ,said

arms being delivered thereto from the inner shell of the rotating centrally disposed column to whichl the rabble arms -are attached, the said cooling medium travelling upwardly and discharged Within the annular passageway lOof the centrally disposed vertically rotating column and is receivedinto the bent pipe- 18, returning through said pipe into the furnace over the lowermost hearth 6a of the furnace and which is the cooling hearth thereof, and ascending up` Wardly from said hearth and into the4 fireA box through the passageways -described and shown for assisting or aiding in the combustion of the fuel of the lire boxes. In this construction ofthe furnace, it is apparent that the ore under treatment passes downwardly through the. apparatus in a zig-zag course of travel over the successive hearths thereof, and during this couise of travel encounters or is subjected to -the counterflowing stream of the hot products of combustion. rllhe combustion of the fuel medium ejected intol furnace and onto the hearth or hearths thereof for intermixturel With the ore charge, combined with the heat received from the fire-boxes, effects the material as moved is effectively carried out on the hearths associated With the fireboxes, and which con stitute the hearths Within the zone of combustion. f

`While l have described the invention in its preferred embodiment, l do not Wish to be understood as limiting myself to the details of construction herein shown and i described, but Wish to be understood as claiming the invention as broadly as the.4 vstate of theart will Warrant for the production of calcined magnesite and calcite more economically, and with closer temperature control than -is possible "With the apr' paratuses at present employed for such purose. y

p Having thus described my invention what l claim as new and desire to secure by Letters Patent of the United States is 1. An apparatus for the described purpose, the same comprising an'outer station-v ary insulated vertically disposed shell, a series of superposed horizontally disposed hearths arranged therein, each provided With outlets for the escape. of material under treatment therefrom, mechanism associated with the hearths for propelling maerial thereover, a series of fire boxes situated outside of't-he shell-and communicating with the interior thereof ,for injecting onto the combustion hearths thereof streams of provided with voutlets for the escape ofmaterial therefrom, mechanism associated with the hearths for propelling thereover material under treatment, a series offire boxes surrounding the shell and communicat-ing with certain of the hearths therein, connections with said boxes extended from vthe bottom portion of the furnace for admitting thereto air for combustion, and means situated outside of the furnace shell for supplying wunder pressure ontocertain `hearths' thereof a carbonaceous fuel medium for intermixing with the material under treatment. e y I 3. lnan apparatus for pose, the combination with the outer shell vided with outlets for the escape of material therefrom, mechanism associated With the hearths for propelling thereover material under treatment, a series of fire boxes surrounding the shell and communicating with the described pur` llO certain of the hearths therein, and connections with said boxes extended from. the bottom portion of the.furnace for admitting thereto air for combustion.

4. ln an apparatus for the described purpose, the combination with theputer-sliell thereof, of a series of superposed horizontally disposed hearths arranged thereiin each provided with outlets .for the 'escape of mathereof, a series of superposed horizontally l1-5 disposed hearths arranged therein, each pro-- terial therefrom, mechanism associated with the hearths for propelling thereover ma,-

terizll` under treatment1 a, series of fire boxes surrounding the hell of the furnoce,`com

5 mu'nications between said lire Boxes and the interior of the furnace for admitting streams of combustionA to certalin of the hearths, Within the furnace, means for supplying nections for leading said air into 'the fire `boxes for purposes of combustion.

Intestimony whereof I have signed my name to this specification.

ROBERT 'D. Pike.

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