US1662939A - Apparatus for smelting the metallic dust and recovering the heat from blast-furnace gases - Google Patents

Description

March 20, 1928. 1,662,939

J. M. scHuTz APPARATUS FOR SMELTING THE METALLIC DUST AND RECOVERING THE HEAT FROM BLAST FURNACE GASES Filed Feb.5. 1924 Jsopfa/ZSW.

Patented Mar. 20, 1928.

UNITED STATES retinas rATENT OFFICE.

JOSEPH MARTIN 'SCHUTZ, or CHICAGO, ILLINOIS, AssIeNoiaBY 'ivr'nsnn' ASSIGNMENTS, T0 CHARLES GILBERT HAWLEY, or crevnmmn omo.

APPARATUS FOR SMELTING THE METALLIC DUST AND RECOVERING THE HEAT FROM BLAST-FURNACE GASES.

Application filed February This invention is allied to those described and claimed in my previous applications S. N. 661,163 and S. N. 661,164, filed September 6th, 1923. To an extent it is set forth in the former; and, this application is concerned with that disclosure as applied to the burning of gases and adds steps and structures peculiar to the smelting and recovery of the metals of metallic dusts either prepared for the purpose, or contained in the gases from blast furnaces and'the like, including the smelting and convenient lisposal of the dusts of producer gas. ts Wlil appear my invention is. adapted for the original smelting of ore that has been re duced to the form of dust with or without a pulverulent fluxing material; but its more immediate use is in the reduction and recovery of the metallic dust contained in blast furnace gases and inthe conservation A of the heat of such gases.

The principal objects and effects of my invention will appear hereinafter.

My invention will be readily understood on reference to the accompanying drawings, in which Fig. 1 is a vertical longitudinal section of apparatus suitable to, and embodying my invent-ion, as associated with steam boiler furnaces for the use of the heat of the gases;

Fig. 2 is the front elevation thereof, onehalf in section on the line 22 of Fig. 1;

Fig. 3 is a horizontal section on the line 3-3 of Fig. 1; and,

Fig. 4 is a vertical cross section of a heating furnace, illustrating a modified form of my invention and smelting burner in which supplementary or gas enriching fuel is employed.

According to my invention the smelting apparatus or burner proper is arranged within a refractory Walled fire chamber, 2, in which the heat of the burning. gases is utilized; as by a steam boiler 3. The part marked 4, is a ductor pipe through which combustion supporting air under pressure is supplied to the smelting burner. The part marked 5, is a like duct or pipe; through which the combustible gas, also under pressure, is supplied to the burner. In practice these ducts, 4 and 5, may be of the same capacity, for in most cases equal volumes of air and combustible gas are required to maintain combustion in the burner. How- 5, 1924. Serial No. 690,863.

ever, in the air damper or valve, 6, and the familiar gas-pressure operated device, 7, connected with the gas duct by the pipe 8, I have provided means for either equalizing or regulatingthe proportions of air and gas; as may be required by the varying richness of the gas, supplied to duct 5; Further, this device, (6, 7, 8) is particularly desirable in the case of smelting burners which because of the combustible. lea-nness of the gas employ a coincident stream of gas enriching fuel, either coal or oil; Such a use is provided for inthe fuel tuyere, 9, of Fig. 4.

With this introduction I. shall first describe the construction and operation of the burner proper and follow that with a description of the dust smelting operation.

The ducts 4 and 5, preferablypositioned one above the other, communicate wit-h respective chambers 4: and 5, preferably having the form of volutes or scrolls, as'well shown in Fig. 3. These are co-axial, and one-above theother. Their outer walls are composed of refractory brick, 10. Their inner walls may comprise metal scrolls, 10 and groutings, 10" of a material such as sand, filling the spaces between the metal scrolls and the conveniently cylindrical brick .wall 10. v The separating floor, 11, between the scrolls, may be made of suitablymolded or shaped segmental fire brick; with a floor covering 11, closing any cracks therein. The part, 12, is a relatively shallow circular bowl, positionedbelow the floor, 57 of the gas chamber or scroll, 5', and preferably composed of suitably moulded or shaped refractory brick. At the center, the 'bowl' has a discharge hole, 12'. Below that is a bucket'tunnel, 13, the use ofwhich will be explained. The top of the scroll 4 is formed by the cover ring, 14, preferably composed of segmental brick, resting on an easily removable sectionalmetallic cover, 14! which-"normally the brick protects from the intenseheat in the; chamber 2. Coaxially with the bowl 12 and the scrolls.4 and 5 I provide two multiple tuyere rings; 15 and 16, one for each scroll; These rings may be identical. Each, is composed of alarge number of overlapping staves or blades, 17, separated by narrow tuyere openings, or spaces, 18. The staves are muchlonger than they are wide and are closely spaced; and therefore the tuyere openings are no more than vertically elongated tangential slits or within the tuyere rings as about to be explained; for the relatively cool air and riphery. of the tuyere ring.

gas passing through the narrow tangential tuyeres absorbs the heat from the metal blades and in each case adequately protects them from burning. The tuyere rings are of the same diameter as the top of the bowl 12, on the top or rim of which the tuyere ring, 16, rests. The top of the ring, 16, meets and supports the inner margin of the separating floor, 11, which contains a large central opening 11" of like size. The floor 11, in turn supports the coaxial tuyere ring 15, and that in turn supports the inner margin of the brick cover ring, 14. The central opening 14;" in the latter, is somewhat smaller than the interior of the tuyere rings, and therefore the inner margin of the cover ring forms or presents an annular overhangin abutment portion, 19, at the top of the tuyere ring 15. This portion 19 when next referred to willbe called an annular abutment, a term which explains its important function in the best performance of the invention.

The whole structure of the burner rests on the floor of the fire chamber 2, or if desired may constitute that floor.

In practice I first heat the burner internally by making alight fire in the bowl 12, and turning on a blast of pressure air through the trunk 4; scroll. 4 and tuyere ring 15. Entering through the many tangential tuy'eres, 18, the pressure air is instantly organized into a thin walled. hollow column of a thickness little exceeding the width of the slit-like tuyeres. Of necessity the air moves in the direction instituted by the tangential tuyeres,-that is, it must needs move forward about and upon the inner periphery of the tuyere ring. Because of the centrifugal thrust developed bythis enforcement of rotary travel within the tuyere ring, the in coming air is forcibly banked against the ring 15, and but slowly if at all expands toward the central axis of the ring. .A

dense whirling column of air is thus organized and maintainedupon the inner pe- The presence of the annular abutment 19, at the top of the ringrprevents the expansionfor movement of the banked air in that direction and therefore the rapidly rotating column of air constantly augmented by the entrance of fresh air through the tangential tuyeres,

moves downward and in rapidly whirling condition enters the top of the bowl 12. There it acts with blow pipe effect upon the initial fire in the bowl and thus combustion in the bowl is hastened, high temperatures are attained from the light initial fire, and the internal brick work of the burner is quickly brought to a temperature that will best admit of the institution of the real processes of combustion and smelting.

Such process of combustion begins with the admission of combustible gas before-the initial fire is exhausted, so that the mixture of air and gas may be igi'iited therefrom. The combustible gas at apressure corresponding to that of the pressure air, is ad mitted through the trunk 5, scroll 5, and tangential tuyere ring 16. The action of the gas within the ring is identical with the described action of the air admitted through the ring 15, save that the upward or direct outward loss or expansion of gas need not be interfered with by a substantial annular abutment, but instead, is prevented by abutment with the downwardly moving whirling column of air from the upper tuyere ring. Thus the whirling column of gas is also forced downwards. Obviously the two col umns of air and gas organized by the use of the slit-like tangential tuyere rings, move downward towards the bottom or bowl 12, and in so moving the air and combustible gases are forcibly and intimately mixed. Being ignited as explained, the forciblymade 'mixture of air and gas burns'in a whirling condition and meeting and re-acting against the bottom bowl, the burning, whirling column finds escape upward along the axis of the burner and out through the opening within the annular abutment portion 19, in the top or cover 14. Meanwhile the central or outgoing burning column radiates heat to the freshly forming columns of air and gas within the tuyere rings and thus hastens combustion, insures perfectness of combustion and makes it possible to steadily maintain combustion within the-burner at all rates of air and gas supply.

Although the entering air and gas highly expand under the almost instantaneous heating to which they are subjected by the outgoing whirling column of flame, the centrifugal vigor of the tangentially organized air and gas columns is always sufiicient to.insure their complete admixture. After such heating and admixturethe further elementof time required for the completion of combustion becomes of little importance, because an adequately high temperature is certain to be always maintained within the burner, andthe actual final combustion of the gaseous products may be conducted and prolonged to the desired degree in any suitable fire chamber (such as external to the burner proper. As here shown the heat of it Whirled or thrown against the inner walls thereof. Thisv being understood the remainder of the process and its several uses concerning the clarification of the gas flames and smelting of metals may now be described.

Receiving, for example, blast furnace gas with its burden of metallic dust and the burner being hot, I direct the gas into the burner through the duct 5; meantime maintaining a proportioned flow of pressure air through the duct 4. The air and'gas being brought into intimate admixture as before described, combustion proceeds within the burner at such temperatures as to melt or fuse the particles of dust. The relatively minute peripheralsubdivision of the gas by means of the multiple tuyere ring, first has the effect of distributing and positioning all dust particles quite uniformly upon the exterior of the whirling column of gas within the tuyere ring; that is, the dust particles are initially and quite uniformly distributed upon or against the inner surfaces of the tuyere ring. Centrifugal force tends to maintain this initial distribution of the dust particles so filtered or strained from the body of gas and deposited on the inner surface of the tuyere ring. The force of gravity and the downward thrust of the whirling columns of air and gas cause the particles to move spirally downward in'the presence of the outgoing central column offlame, from which much heat is received. The relatively cool incoming gas doubtless serves to withhold the particles from complete fusion until they reach the bottom bowl. There, the heat is so intense that the gathered and constantly gathering particles are quickly fused or melted. A film-like mass of molten metal with a superimposed film of dross or slag is thus formed on the bottom of bowl, providing a new surface for it, against which the burning gases whirl and react into the described central outgoing column of flame. Clearly, the refractory bottom is always kepthot. .The accumulation of molten metal and slag proceeds rapidly and is discharged in a continuous stream through the hole 12 in the bottom of the bowl.

As before stated, I prefer that the hole 12 shall be central; this to the end that the molten material shall have uniform opportunity of discharge from all parts of the bowl, 12; and for the further reason that at times it may be necessary to introduce pulverized coal, or oil, (as through tuyere 9) to enrich a lean gas, in which case the periphery of the bowl should be iniperforate, lest the added fuel be permitted to escape from the .bowl' before it is consumed. I As contrasted with those systems in which the gasis cooled by a washing process that removes the dust, my invention takes the gas at whatever temperature it comes from the blast furnace or' other. source; and thus the contained or initial heat of the crude gas is saved, and obviously the combustion in the burner is advantageously hastened.

The valuable metal contained in blast furnace dust is of such quantity and quality as to be well worth saving; indeed the saving herein prescribed offsets a considerable part of the cost of blast furnace operation.

V Ordinarily the walls and'contents of the fire chambers, ovens or stoves in which the gas is burned, receives much fused and sintered dust; and after relatively short runs are so befouled as to require shutdowns, expensive cleanings and frequent reconstructions. A distinct advantage of my invention, one of quite as much importance as the saving of metal, resides in the above described clarification of the gases prior to their release into the fire chamber. The dust having been fused and .removed in the described burner, it is obvious that the burning gases leave the burner in a clean, clear condition andthat the operation of the fire chamber, oven, stove, or boiler, may be continued indefinitely, without regard to the befouled condition of the gases furnished to the burner or burners.

Save that thedescribed clarification of the gas sequentially follows the smelting of the dust, such clarification very properly might be set forth as the chief object of my invention; such is the industrial importance of the gas clarifying operation.

VVhe-never the dust burdened gas is too poor or lean in comb u stibles to maintain the proper combustion, I introduce enriching fuel through one or more fuel feeding tuyeres, such as the tuyere 9 shown inFig. 4. I In some cases the bowl 12 may be somewhat deepened; to slightly increase the period or time of the exposure of the incoming fuel on the Walls of the burner bowl. fuel merely augments the combustibility of the mixture of air and gas. The fuel is held at the periphery of the bowl by the whirling motion of the gaseous mixtures and escapes only as it is decomposed and combusted. Any ash in the fuel is quickly fused and directly added to the molten mass or slag from themetallic dust. In other respects the process is the same as before described. I

By adding another kind or kinds of pulverulent ore. or metal, to the stream of dustladen gas flowing through the duct 5, I

The added easily convert the smelted dust into any desired alloy.- As the mixing of the gas and different kinds of metallic dust is easy of mechanical accomplishment and isthe only step required for the production of alloys, for example, manganese products and the like, I have thought it unnecessary to illustrate the obvious mixing device that feeds the added dust to the gas duct 5.

lVhere a clean gas is available, I employ the same in the above described manner, but for the original smelting of pulverized metallic ores. The use or non-use of pulverulent fluxing material is determined by the character of the metallic dust to be smelted. Obviously the process remains the same, however the dust is admixed with the stream of combustible gas, whether natural or artificial.

Similarly, when equipped with a pulverized coal or oil burning furnace of the kind illustrated in my application S. N. 661,164, the same may be employed for the original smelting of ores by feeding the pulverized ore directly into that furnace, preferably through the agency of the air blast and the multiple tangential tuyere ring. \Vhen coal is the fuel employed the quantity of molten slag is obviously increased; otherwise the smelting process, the combustion process and the utilization of the heat of the combustion are as above described.

By preference a mold 20 is placed beneath the discharge hole 12 of the burner to receive the molten metal and slag therefrom. A very good gravity separation of molten -metal and slag takes place in the mold and by changing the molds as rapidly as they are filled the material may be very conveniently pigged or cast into blocks. the slag easily separates or breaks off from the, underlying metal, leaving a pig of metal that may be utilized as would any other mass of the same metal or alloy. For convenience the pigging molds 20 are metal 'buckets or When cooled chills arranged in the form of a traveling belt that slowly conveys the pigs from the tunnel 13, to the point of their discharge. Obviously any suitable device, mold, progressive furnace, or metallurgical hearth may receive the molten metal directly from the described smeltin burner.

It should be explamed that the annular abutment "19 of the burner ma be done away with without materially interfering with the herein described smelting operation; but in such case much of the pressure air will escape into the fire chamber direct from the top of the burner and nice-ty of combustion and ease of control will be lost. Hence it seems best always to employ the abutment 19 or at least some operating equivalent that will compel the described downward travel of both the air and gases before they can escape from the burner.

Further, my invention may be modified and used in other ways by those who are skilled in the art; and, all without departing from the spirit or scope of the invention as herein described and claimed.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. The herein described gas burning furnace comprising a bottom bowl, in combination with superposed multiple-tuyere rings and an overhanging annular abutment, and means for supplying pressure air and gas through respective tuyere rings.

2. The herein described gas burning and dust smelting furnace comprising a refrace tory bottom bowl containing a central metaldischarge hole, in combination with superposed multiple-tuyre rings and an overhanging annularabutment, and means for feeding air and gas to respective rings.

In testimony whereof I have hereunto set my hand this 31st day of January, A. D.,

JOSEPH MARTIN SCHUTZ,

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