US2190493A - Sintering apparatus - Google Patents

Description

Feb. 13, 1940. H. J. sTEHLI SINTERING APPARATUS Filed Oct. 25, 1938 gn Q -Jgw uw?? nw resented Feb. 1 3, 1940 UNITED L STATES PATENT Aori-Ica sm'rnamc. APPARATUS Henry J. stehn, cedar Grove, N. J. Appueaaen october z5, 193s, serial No. 236,840

solenne.

My invention relates to sintering lapparatus, both to machines of the Dwight 8: Lloyd continuous type, and to the intermittent or pan type.

sintering machines of the continuous type con- 5 sist of a suction box or a series of suction boxes over which pass pallets or cars having a pervious bottom and filled with a charge of ore. 'Ihe pallets or carsvmake very close contact with the top of the suction boxes to form an air seal, the l effect vof the suction being to draw the cars pallets downwardly onto the edge of the suction boxes to form an effective seal. The charge of ore in the cars is combustible or is admixed with a fuel and,lupon being ignited at the top surface as l it passes over the suction boxes, the down draft of air causes the charge of material on the pallets or cars to burn progressively downwardly from the top to' the bottom of the charge. v The pan type sintering apparatus consists of a go pot orvpan provided ,with a grate bottom and having an exhaust box underneath the grate. In operation, the charge is placed on the grates, levelled off and. ignited at the top surface, and air is drawn through the bed to burn the fuel as in 25 the continuous type. l In the operation of sintering apparatus, the

gases passing into the suction box are hot and generally full of dust, acid constituents and, sometimes, sublimedsulphur, volatilized metals or 30 metallic oxides, or other corrosive materials, de-

pending upon the charge on the apparatus. These h ot gases are, therefore, very destructive to the blowers and it has therefore been necessaryto use fans of the centrifugal type having wide clear- 35 ances and low` mechanical efficiencies. Under certain conditions as, for example, when chlorine gas is liberated during the roasting ,or sintering,

such centrifugal fans are rapidly attacked unless built of expensive material such as corrosion re- 40 sistant alloys. In the above types of sintering apparatus the amount of suction or pressuredifference between the top and bottom of the charge is limited. For example, it is dimcult to obtain a vacuum much greater than 20 inches of water,

45 due to cost, and there is generally an upper limit to the vacuum of about 28 inches of water.

Efforts have been made to overcome these limitations by supplying air under pressure'to the top of the sintering machine and thereby to run the 50 machine under pressure rather than under vacuum. For this purpose it has been proposed to provide a pressure hood above the sintering machine and fitting tightly on the upper edges of the moving cars or pallets. Although this avoids 55 the necessity of passing hot gases through fans or (Cl. 26S-21) blowers or exhausters, other difficulties have been encounteredwhich have proven substantial obstacles to the successful operation of the machine.

Among these diiiiculties is that of making a satisfactory seal joint between the cars or pallets 5 and the pressure wind box or hood above the machine. To provide a seal with a wind box, it is necessary to have cross partitions at each end of the cars or pallets to make an end seal as well as to seal the sides of the cars to the wind box. These cross partitions interfere with the even feeding of the cars and must be swept free from the charging material in order to form a tight seal and are subject to rapid destruction by the flame of the ignition burner and also to warping from the effect 15 of heat. The effectiveness of the seals is, therefore, subject to impairment due to the above and other causes. The pressure hood or wind box also serves to prevent access being had to the material being sintered so that if local conditions interfere with proper sintering as, for example, if blow holes develop, they cannot be quickly detected and plugged. l

In my present invention I avoid all of the above difficulties of the suction and wind box arrangements and provide a sintering apparatus in which air for combustion may be supplied under pressure, thereby avoiding the necessityl of handling or exhausting hot exhaust gases, and in which a pressure differential through the sintering bed of 30 any desired magnitude may be maintained, and in which the sintering be'd is open and accessible to the operator.

In my invention I enclose the sintering apparatus, or a number of sintering apparatus, each of which is provided with a collection or exhaust box or system similar to the suction boxes heretofore used, in a room or structure maintained under air pressure. 'I'he pressure of the exhaust gases leaving the sintering apparatus may be 40 either at atmospheric pressure or slightlyabove or below atmospheric pressure, depending upon the stack conditions if the exhaust gases pass directly toa stack, or upon the conditions in the treating apparatus if the gases are subjected to. further treatment. Air under suitable pressure is continuously supplied to the room o; enclosure within which the sintering apparatus is operated.

-Ore or other charging material is also continuously supplied and distributed on the upper surl face of the charge. holders. 'I'he ore material is ignited from a burner, or other suitable means, in its initialv passage or entrance over the' exhaust boxes and thereafter downward combustion is maintained by the air under pressure passing '5 1 downwardly through the ore charges to the offtake or exhaust boxes. The sintered material discharged from the sintering apparatus is then taken from the enclosure or room by a water seal, air lock or other discharge means. Air may be supplied to the building or structure under any suitable pressure to maintain the proper draft. A pressure of 2 to 3 pounds per square inch will usually be the maximum required. The operators for running the sintering apparatus may, therefore, be within the enclosure or room inasmuch as this pressure will cause no substantial discomfort.

The various features of the invention are illustrated inthe accompanying drawing, in which- Fig. 1 is a diagrammatic vertical section of a continuous sintering apparatus embodying my invention. y

Fig. 2 is a similar section of a part of a sintering apparatus embodying a different arrangement of the section box.

In the apparatus show-n in Fig.' 1, a sintering machine, comprising a chain of pallets or cars IIJ passing between pairs of supporting 'wheels II and I2, is positioned within a room or .enclosure I 3. In its upper flight the chain of pallets passes over and is supported on the structure of an exhaust box I4 having an outlet or exhaust ue I5 leading to a stack I6 outside of the enclosure I3. Air under pressure is supplied tothe enclosure or room I3 by means of a blower I1 which delivers through a delivery pipe I8 into the enclosure I3. The air under pressure thus supplied to the enclosure I3 passes downwardly through the upper flight of cars or pallets into the exhaust box I4, as indicated by the arrows, and thence into the exhaust flue I5 leading to the stack I6.

The material to be sintered as, for example, ores, ore concentrates, fuel, colloids or other reagents, may be supplied from one or more bins I9 by means of automatic feeders 20 to a common conveyor 2| and thence delivered to an open ended hopper 23 mounted in the roof of the building I3, and having its lower end within the build-' ing. The material is fed from the lower end of the hopper 22 by means of an automatic feeder 23 driven by a belt or other transmission 24 from the driving wheel II of the sintering machine. 'I'his ensures a speed proportionate to the speed of the sintering machine. -The feed, however, may be regulated by means of a control gate 25. The mass of material in the hopper is generally sumcient to seal the room against undue loss of air but if not a suitable sealing device may be provided.

The material from the hopper 48 passes into a mixer or pelletizer 26 from whence it is-delivered to a feed hopper 21 at the front end of the sintering machine and by which it is spread in an even bed onto the traveling pallets or cars. 'Ihe material thus spread onto the pallets passes beneath a burner 28 where it is ignited and, in its further passage over the exhaust box I4, is burned in a descending zone until it is completely sintered.

As the pallets pass over the wheels I2 at the delivery end of the sintering machine, they drop the sintered material into a water seal 29 from which it may be lifted by a bucket or other type of conveyor 30 outside of the building and delivered into a car 3|, or other receptacle.

The wall of the building I3 extends into the water seal 29', as at 32, to maintain the seal while permitting the sintered material to pass therethrough. l

In the modification shown in Fig. 2, the exhaust box i4 is provided with partitions n which divide the exhaust box into a number of separate chambers 34. The chambers immediately below the ignition burner 28 exhaust through a pipe Il,

the chambers in the central part exhaust through a pipe 36, and the end chambers exhaust through a pipe 31. 'Ihis permits separate treatment of the different gases. For example, the gases being exhausted through the pipe 3B from the central part of the sintering apparatus may be rich in sulphur dioxide and, therefore, useful directly for acid making. The gases passing through the exhaust pipe 35, from immediately beneath the ignition burners, may contain gases unsuitable dlrectly for the making of acid, and may be treated specially. 'Ihe gases passingthrough the .exhaust pipe 31 may be free of anyuseless or deleterious materials and may, therefore, be exhausted directly to the atmosphere. It will be understood, of course, that the particularl treatment of the exhaust gases may vary.

It will be understood that the illustration in the drawing is merely by way of example, and that any suitable enclosure may be employed, either about each individual sintering machine or, if more than one sintering machine is in operation at a time, a single enclosure may be employed for several such machines.

Through the above invention I am able to maintain a relatively high air pressure on thematerial being sintered and avoid the diiiiculties of maintaining an air tight seal between the traveling pallets and the pressure hood. Inasmuch as the air is supplied while cool, dense and free from dust and corrosive materials, eiiicient blowers such as Turbo blowers, rotary blowers, or other positive pressure blowers having slight clearance spaces and high mechanical eiciencies may be employed. Moreover,as the air is blown into the building in largeV quantities and thence passes into and through the sintering machine, it tends to clear the atmosphere within the building Yor enclosure of dust, fumes, etc., which are carried into and through thesintering bed. This makes working conditions about the sintering machine much better than would bejthe case if a pressure hood or a suction apparatus were employed.

In my invention it will also be notedl that by partitioning the exhaust boxes, gases of diierent qualities may be withdrawn from the different parts of the sintering machine without requiring a fan or exhauster for each gas withdrawn.

What I claim is:

1. sintering apparatus which comprises a sintering machine having successive moving pallets for supporting a bed of material to be sintered, an exhaust box below and sealed to the pallets of said sintering machine, a room enclosing said sintering machine, and means to supply air under pressure to said room.

2. sintering apparatus which comprises a sininganumberofpartitiomdlvldingitintosepu' l arate compartments, a room enclosing said sintering machine, means to supply air under pressure to said room, and means to supply sintering material to said room.

4. sintering apparatus which comprises a sintering machine having successive moving pallets to support material to be sintered, means to ignite the material on said pallets, an exhaust box below' and sealed to said pallets, said exhaust box having a number of partitions dividing it into separate compartments, a room enclosing said sintering machine, means to supply air under pressure to said rooni, means to supply sintering material to said room and to said sintering machine therein, and means to withdraw sintering material from said room.

5. sintering apparatus which comprises a sintering machine having successive moving pallets to vsupport material to be sintered, means to ignite the material on said pallets, an exhaust box below and sealed to said pallets, said exhaust box having a number of partitions dividing it into separate compartments, a room enclosing said sintering machine, means to supply air under pressure to said room, and a water seal into which sintered material is delivered and from which it may be withdrawn outside of said room.

6. sintering apparatus which 'comprises a room, a sintering machine in said room, said sintering machine having continuous moving means to support material to be sintered, an exhaust box below said means, means for suplesser pressure than that o! said room,

plying material to be sintered to said continuously moving sintering means. and means for supplying air under pressure to said room.

7. sintering apparatus which comprises a room, a sintering machine in said room having a moving grate for the support of material to be sintered and an exhaust box below and sealed to said grate, means to maintain said room and the upper part of said grate at super-atmospheric pressure, and means to conduct exhaust gases from said exhaust'box at approximately atmospheric pressure.

8. A process of prises supplying said sintering material which commaterials to a room under super-atmospheric pressure, spreading said material in a layer in said room and continuously passing said layer over an exhaust chamber at a igniting said layer as it passes over said exhaust chamber and burning it with a down draft of air.

9. A process of sintering material which comprises supplying said materials toa room under super-atmospheric'pressure, spreading said material in a layer in said room and continuously passing said layer over an exhaust chamber at a lesser pressure than that of said room, igniting said layer as it passes over said exhaust chamber and burning it with a down draft o! air, and separating the exhaust gases in said chamber into separate streams at successive distances in its path of travel.

HENRY J. BTEHIJ.

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