US1802959A

US1802959A - Process and apparatus for the gaseous treatment of finely-divided material

Info

Publication number: US1802959A
Application number: US348632A
Authority: US
Inventors: Francis M Simonds
Original assignee: FILLMORE HYDE A
Current assignee: A FILLMORE HYDE; FILLMORE HYDE A
Priority date: 1927-03-12
Filing date: 1929-03-20
Publication date: 1931-04-28
Anticipated expiration: 1948-04-28

Description

April 28, 1931.

PROCESS AND APP F. M. SIMONDS Filed March 20, 1 29 ARATUS FOR THE GASEOUS TREATMENT OF FINELY DIVIDED MATERIAL 6 Sheets-Sheet l Apia}; 28%, 1931. F. M. SIMONDS L Z PROCESS AND APPARATUS FOR THE GASEOUS TREATMENT OF. FINELY DIVIDED MATERIAL Filed March 20, 1929 6 Sheets-Sheet 2 i 11? 5;" w W Apn 28, 1931. I F. M. SIMONDS 1,892,959

PROCESS AND APPARATUS FOR THE GASEOUS TREATMENT OF FINELY DIVIDED MATERIAL Filed March 20, 1 29 6 Sheets-Sheet 3 PROCESS 'AND APPARATUS FOR THE GASEOUS TREATMENT OF FINELY DIVIDED MATERIAL I Filed March 20, 1929 6 Sheets-Sheet '4 April 28, 1931. M SIMONDS E 2&5?

Apni 28, 1931. F. M. SIMONDS i,802,959

PROCESS AND APPARATUS FOR THE GASEOUS TREATMENT OF FINELY DIVIDE?) MATERIAL Filed March 20, 1 29 6 Sheets-Sheet 5 f M. anomtoz April 28, 1931. F. M. SIMONDS 1,802,959

PROCESS AND APPARATUS FOR THE GASEOUS TREATMENT OF FINELY DIVIDED MATERIAL Filed March 20, 1929 6 Sheets-Sheet 6 .Patented Apr. 28, 1931 7 UNITED STATES PATENT oer-"Ice FRANCIS M. SIMONDS, OF NEW YORK, N. Y., ASSIGNOR OF ONE-HALF TO A. FELIIMORE HYDE, OF NEW YORK, N. Y.

PROCESS AND APPARATUS FOR THE GASEOUS TREATMENT OF I'llNIEIaY-IDIVIDEID- MATERIAL Application filed March 20, 1929, Serial No. 848,682, and in Canada March 18, 1927.

such as ground ores, pulverized ores, flotation concentrates, and admixtures, the desirability of bringing gases, and especially hot gases and corrosive gases, into intimate contact with the ores or other material has been recog- 15 nized (see for instance Bureau of Mines Bu1- letin #721927), but great difiiculties have been encountered in obtaining an intimate contact. of the gas with all parts of the ore, in treating material on a large scale, in efficiently usin large volumes of gas in closely regulating t e temperatures of the gases and reactions, and in avoiding reverse and undesired reactions. Furthermore, great difiiculties have been encountered in carrying out such treatment in a continuous manner, owing to limitatlons upon the use of apparatus com rising moving conveyors, particularly in t e presence of hot or corrosive gases.

The present invention provides a method and apparatus for the gaseous treatment of finely divided material, (such as ores) in which movement of the material throughthe furnace is efi'ected by impacts of gas against theunderside of a layer of material on the furnace hearth, thereby avoiding the use or moving parts within the furnace, and is hence particularly adapted for gaseous treatment of material carried out at relatively high temperatures (red heat for example). The gas or gases pass through the. layerof material on said hearth and an intimate and efiicientuse of the gas is thereby provided. The invention further provides a method and means for closely regulating the temperatures of the gases and reactions; and for \vithdrawin said gases after "passing through sai ore, whereby reverse and undesired reactions in the material on thehearth are avoided.

Th invention further provides a process served, space economized, and a simple and serviceable structure provided."

The invention provides other features of advantage which will appear in connection with the description which follows:

An embodiment of the invention is illue trated in the accompanying drawings, where 111 I Figures 1 and 2 are vertical sectional views of said embodiment, Fig. 1 bein a section at the feed end of the furnace, an Fig. 2 being a sectional view at the discharge endof the furnace.

Figs. 3 and 4 are related views, showing a horizontal section of the part shown in Figs.

- 1 and 2, the section being on the lines 3-3,

Fi 1, and H, Fig. 2.

ig. 5 is a transverse sectional view on the line 5-5, Fig. 1. a

Fig. 6 is a transverse sectional view on the line 66, Fig. 2.

Fig. 7 is an enlargedtransverse sectional view through the furnace at an intermedia part.

Fig. Sis a view on the same scale as Fig. 7, being a transverse sectional view on the line 88, Fig. 7, looking in the direction 01 the arrows, the steel posts in front of the line of section, however, being shown.

' Fig. 9 is a section through a part of the structure shown in Fig. 7, in on the line 9-9, looking in the direction 0 the arrows. Fig. 10 is a longitudinal vertical section through a portion of the hearth;

Fig. 11 is a transverse sectional view through the hearth at the left-hand side of the furnace, Fig. '31 g and Fig. 2.2 is a verticalsectional view showing a modification of the impeller and ducts, shown at the upper side of- Fig. 4.

Referring to said drawings, numeral 1 designates the furnace, comprising base 3,

side walls

4 and 5, and roof 6.

Numeral 10 designates the hearth. For conservation of space and also of heat, the hearth is conveniently divided into a plurality of superposed sections, here shown as three.

Numeral 12 designates a hopper for feeding finely divided material onto the hearth, and numeral 114 designates a bin, which is preferably a closed bin, as shown, for receiving the treated material at the discharge end of the furnace.

The divided material is moved along the hearth by means of a succession of impacts of gas against the underside of the layer of material on the hearth. The hearth is preferably level or approximately level.

Beneath the layer of material on the hearth there are arranged gas passages 16, Fig. 10, which gas passages 16 are upwardly inclined with relation to the ore layer, and are adapted to direct impacts of gas against the underside of the ore layer in such manner as to move or push the ore layer along the hearth in a direction to move it toward the discharge end of the furnace. The inclination of the passages 16 is preferably such as to direct the impacts at a small angle to the underside of the layer of material on the hearth.

The passages 16 are conveniently formed in the hearth itself. The hearth for this purpose may be composed of a number of bars 18 extending across the inside of the furnace, and spaced slightly apart, so as to allow an opening between adjacent bars. Each of the bars 18 is provided with an extension 20 (a plate for example), the extension on one bar extending over an extension on an adjacent bar and leaving a narrow space (for example, one-eighth of an inch between the plates), the said overlapping extensions 20, together with the top side of the bars 18, constituting the walls of the passages 16. The extensions 20 preferably extend across the furnace and thereby rovide narrow gas-passages 16 running rom side to side of the furnace.

Inasmuch as the material being treated is usually considerably smaller than the width of the passages 16, and furthermore inasmuch as at elevated temperatures, as for exam le 500 or 600 (3., the material has a mobility very similar to dry talc, the passages '16 are formed throughout, or at least with a part, so little inclined that the finely divided material, will not run down through the same. As shown in Fig. 10, the bars 18 are provided'with such a portion 22 for preventing the material running through the said assages. As shown, this portion 22 has a slight inclination in the reverse direction to the upper portion of the said passage 16,

Gas chambers 24 are preferably arranged beneath the bars 18, with which the passages 16 communicate. The chambers 24 are conveniently formed of blocks or plates 26 which extend across the furnace and constitute the bottom of the gas-chamber 24. In case of breakage of one or more of the bars 18, the material would be caught by the said blocks or plates 26.

The hearth is preferably divided longitudinally into zones for carrying out different treatments of the material. For this purpose, among others, the chambers 24 are divided transversely, as shown at 28, so as to admit of gases of different composition being introduced to the hearth at different 1ongitudinal zones. The gases are introduced to the chambers preferably through lateral passages 30 in one of the side walls of the furnace, as for example in the side wall 4, and these passages 30 preferably communicate with the

ducts

32, 33, 34, 35 running longitudinally of the furnace, and preferably arranged in one of the side Walls, as for example theside wall 4. Four of these ducts are shown, and these ducts may carry gases of difierentcomposition. For example, the duct 32 may carry an inert gas. The duct 33 may carry a similar gas, and

ducts

34 and 35, a reducing gas, as for example producer gas, water gas, etc. The ducts may be conveniently and advantageous: ly formed as channels in a block or blocks 38 laid up in the side wall 4, .so that the open sides communicate with the lateral passages 30. Gas to the

ducts

34 and 35 is conveniently supplied from producer 40, or other similar source, the gas from the said producer conveniently flowing to the said duct 34, through a main 42, manifold 44, pipes 46, manifold 48, opening 49, impeller 50, and thence into said duct 34.

The producer gas may also be supplied to the opposite ends of the duct 35, by an impeller 52 in communication therewith and taking producer gas from the manifold 44 through the opening 53.

The pipes 46 containing the producer gas are preferably arranged in a heating chamber in the bottom 3 of the said furnace, the pipes being supported in spaced relationship in a veniently delivered to the

passages

32, 33 by impellers 60, 61, arranged at each end of the. furnace in communication with the'ends of the said

ducts

32, 33 and in comm nication I with the said chamber 55 through ducts 62, 63' (see Figs. 5 and 6).

As the gases in the chamber 55 are at a higher temperature than the producer gas en'- tering through pipes 46, the said producer gas will be heated to approximately the temperature of said chamber.

The gas passing through the hearth 10, and the layer of material thereon, is-carried away in any suitable manner, as through lateral ducts 65 communicatin" with

longitudinal ducts

67, 68, 69 referdbly arranged in the sidewall 4 of the urnace.

Above the layer of material on the hearth and between it and said ducts 65 there is preferably arranged a filter 72 of an suitable construction, as for example as estos. The fine dust caught by said filter 72 falls back onto and mixes with material on the hearth which has received the same degree of treatment "as it has.

The ducts 65 serve to carry off the gases immediately after passing through the layer of material on the hearth (and through the filter) and thereby carry them away from said material where they might otherwise react undesirably or reversely.

The

ducts

67 ,68, 69 may lead to a stack, or to a recovering apparatus for recovering such produhts from the gas as may be of value, and also for returnlng to the system,

gas which may be again used in the process with or without regeneration, as may be necessary or desired.

The impeller 52 is conveniently of similar construction to the impeller 50. The action of these impellers is to produce sharp quick impacts of gas against the underside of the layer of material on the hearth, through'the inclined passages 16 (by way of chambers 24,

. lateral passages 30 and

channels

32, 33, 34,

35 in the illustrated construction). Any suit-- able impellers for effecting this action may be used. As here shown, the impellers comprise a reciprocating part or piston 75, working in a cylinder or sleeve 77, the

parts

75 and 77 preferably being slightly spaced so as to avoid rubbing action at-hightemperatures. The front of the piston 7 5 is preferably provided with a valve disk 79 adapted to open when the piston 75 is pulled back, and to close when it is shot forward. The disk 79 on the back movement of the piston, op ns and allows gas to pass to the front side of the piston. and also avoids suction or drawing back of the gases by the piston. In order to further avoid drawing back of the gases by the piston 75, a valve 81,0pening toward the passage 35, may be placed in the cylinder 77 or other suitable location ahead of the said piston 75. Or, as shown in Fig. 12, a valve 150 (such for example as a so-called fiutter valve) may be placed in said sleeve or cylinder '77, ahead ofthe piston 7 5, and adapted to open on the backstroke of said piston and admit gas from the supply duct tothe front of the piston. The piston 75 is reciprocated in any suitable manner so as to strike sharply against the gas,

shot forward by compressed air as in an air. gun or by a spring, the return stroke being made by cams at a relatively slow speed.

Other mechanical devices could be used. The object, to be-attained is a rapid forward stroke to give the shock to the air and a relatively slow return to avoid back suction and also to allow gas to continually ass through the ore. For example, the piston 75 may be driven by a piston 141 working in an air cylinder 142 (Fig. 4). A rotating cam 144 serves to force the piston 141 toward the back of the cylinder 142, compressing air, which, when the piston is released by the cam 144, shoots the piston 141 forward, and likewise the piston 7 5, thereby delivering ,a quick sharp impact to the gas in cylinder 77. I have obtained good results within the range of one to six impacts The impacts of the gas are such that momentarily, during such impacts, the passage of the gas through the layer of material is clicked, in such manner that the resultant pressure of the gas against the underside of said. material acts to impart movement tothe layer of material'along the hearth. Moreover, the pressure of the gas against the underside of the layer of material on the hearth is higher than that above the hearth, so that there is normally a constant or steady flow= of gas through the material; The impacts of gas against the underside of the material are moreover effected in such a way as to avoid a jigging action on the material, which would result in a separation of the fines from the coarser material. It is preferable, particularly in ore treatment, to maintain a nearly approximating the perpendicular, that sepa-' ration of the fines and coarse particles occurs. Angles from 10 to 30 I have found most suitable for my purposes; that is, of maintaining a'high degree of homogeneity of the coarse and the fine material, and that/up to about 45 fair results may be obtained.

The maintenance of a good mixture-of the fines and the coarse is of importance where interactions take place between the particles, as for example in the treatment of complex ores, in using materials which are mixed together expressly for interaction, etc.

To facilitate feeding of the material on the hearth at the start, means are provided for closing off the gas to those portions of the hearth not covered by the material to be treated. For this purpose dampers 80 are provided for controlling the passages leading to the gas-chambers 24 which communicate with the passages 16 in the hearth. In starting to feed. material from hopper 12 to the hearth, all dampers 80 are closed except that controlling the flow of gas to the first gas-chamber 24, and as the material is fed forward, successive dampers are opened until the layer reaches the discharge end of the hearth.

As heretofore described, the

passages

30 and 65 and also the channels or

ducts

32, 33, 34, 35, 67, 68, 69 are preferably arranged in one. side wall (4) of the furnace, leaving the opposite side .wall (5) free of passages and adaptable for removal in whole or in part for making replacements of parts within the furnace, particularly the parts constituting the hearth 10 and filter 72.

To further adapt and facilitate the. construction to the ready replacement of parts, the bars 18 are made of a length to extend across the furnace, and a recess 82 is provided in the side wall 4 for receivin and supporting an end of the bars 18. he filter 72 is also preferably made in transverse sections (see Fig. 8) extending across the fur? nace, and a recess 84 is provided inside wall 4 for receiving and supporting an edge portion of each filter section. Similarly, the plates or blocks 26 are constructed in transverse sections, and a recess 86 provided in the side wall 4 for receiving and supporting an edge of said sectional plates 26. Asbestos wool may be placed in said recesses 82 and 84, as indicated at 90, to pack the joint between the walls of the recesses and the parts fitting therein.

With a stationary hearth. as described, a snug joint can be made with the side walls of the furnace, and all gas-forced to' pass through the material, thereby securing greater efiiciency and economy than possible with a moving hearth.

The side wall 5 is conveniently provided with a plurality of vertical columns 93 of steel or the like, and brackets 95 fastenedto seal, insulate and fill out the wall 5. The

material 103 is readily removable, and after If it be desired to oxidize material, as for example to roast sulphide ores, means are provided for introducing air into said inert gas, and preferably in independently controllable quantities into the gas introduced into the several gas-chambers 24. For this purpose pipes 105, controlled by valves 107 may be-provided, communicating conveniently with the lateral passages '30 leading into the gas-chambers 24. The several pipes 105 may connect with a main 109 supphed with air under pressure, as from a low-pressure blower 111. Letter 0, Figs. 2 and 8, designates a part of the oxidizing zone in the embodiment shown.

In order to break up compounds which at the temperature used do not dissociate under continued oxidation, it is desirable to alternately subject such compounds to alternate reduction and oxidation. For example, in

the process of roasting sulphide ores, it issometimes desired to subject the ores during a stage of the roasting, alternately to oxidation and reduction in order to break up sulphur-oxygen compounds with the metal of the ore. For this purpose the hearth (an intermediate portion designated by letters O-R, Figs. 2 and 8, in the embodiment shown) may be constructed to receive in v alternate gas-chambers 24, oxidizing and reducing gases. Referring to Figs. 7 and 8, eaclr of the gas-chambers 24Rare shown as communicating with the duct 34 containing reducing gas through lateral passages 30-R (Figs. 7 and 9), and each of the chambers 24O are shown as communicating with the duct 33 (through lateral passages 30-0, Fig. 9) and with an air pipe 105, whereby an oxidizing gas is introduced to the chambers 24O. The pipes 105 may be used for introducing. other gas than air into the gaschambers 24, where other treatment of the material than that efiected by air is desired, and the valves 107 may be used for closely regulating the temperature and character of the reactions taking place at various parts of the hearth.

The after part of the hearth, in the illustrated embodiment a part of which is designated by letter B, may be used for reduction of the'roasted ores, for which purpose reducing gas is supplied from the duct 35 to the -chambers 24 in said after part of the earth.

Before discharging reduced ores, and many other kinds of material into the air, it will frequently be desirable to reduce thetemperature of the material after the treatment with hot gas has been finished. For this purpose the hearth 10 may have a prolongation 115 extending into the closed discharge bin 114 in which prolongation cool or relatively cool as is used for moving the ore layer. As s own, relatively cool gas from the gas producer 10 is ledthrough a pipe 117 to a duct 119 communicating through lateral passages 121 with gas-chambers 24 in the hearth at said prolongation 115 thereof, and an impeller 125, similar for example to the impeller 50, is provided for produ impacts of the gas admitted through pipe 11 on the material on the hearth for moving said material along said prolongation 115 of the hearth. The gas may be led ofi and burned to produce hot products of combustion for the heating chamber 55. The said gas from the prolongation 115 may passofi through lateral-openings 127 above the filter 72 and pipe 129, and be mixed with air from a pipe 131, and burned as it issues from said pipe 129.

A description of the process of my invention and 0% a mode of procedure in which said process is carried out, has been given in connection with the foregoing description of the apparatus and its operation.

The apparatus of my invention may receive other embodiments than that herein specificall illustrated and described, and the process 0 my invention may be carried out in other modes of procedure than that herein specifically described.

What is claimed is i 1. Apparatusfor the gaseous treatment of finely divided material, comprising a hearth on which a layer of said finely divided material ma lie, and means for moving said layer of ely divided material along said hearth, comprising a source ofhot gas, and means for im artmg a succession of sharp impacts of said hot gas against the underside of said'layer of material, said gas under the pressure of said impacts being momentarily choked in its assage through said layer of material and y the resultant pressure against the underside ofsaid material effecting said movement of said layer along said hearth.

2. A paratus for the gaseous treatment of finely 'vided material, comprisinga hearth on which a layer of said finely divided material ma lie, and means for moving saidv layer of nely divided material along said hearth, comprising a source of hot gas, and means for im artmg a succession of sharp impacts of said hot gas against theunderside of said layer of mater al said gas under the pressure of said impacts being momentarily choked in its assage through said layer of material and y the resultant pressure against the underside of said material efiecting said movement of said layer along said hearth, and means for maintaining a flow of gas through said layer of material between said impacts.

3. Apparatus for the gaseous treatment of finely divided material, comprising a hearth on which a layer of said finely divided material may lie, said hearth being divided into a plurality of zones, and means for moving said layer of finely -divided material along said hearth, comprising a plurality of means for imparting a succession of sharp impacts of gas against the underside of said layer of material at said plurality of zones, and means for supplying gasesof difi'erent composition to said zones.

4. Apparatus for the gaseous treatment of finely divided material, comprising a hearth on which a layer of said finely divided material may lie, and means for moving said layer of finely divided material along said hearth, comprising means for imparting asuccession of sharp impacts of inert gas against the underside of said layer of material, and means for furnishing to said inert gas a limited quantity of a constituent active upon said material the proportion of which active constituent is such that reaction thereof on said material does not produce such an increase of temperatureas to produce sintering.

- 5. Apparatus for the gaseous treatment of finely divided material, comprising a hearth on which a layer of said finely divided material may lie, and means for moving said layer of finely divided material alongsaid hearth, comprising means for impartin a succession of sharp impacts of hot gas a amst the underside of said layer of materia and means at the discharge end of said hearth for.

supplying cooling inert gas to said material whereby said material is made inactive on meetingthe air. 6. A paratus for the gaseous treatment of finely. ivided material, comprising a hearth on which a layer of said finely divided material may lie, and means for moving said layer of finely divided material along said .hearth, comprising means for imparting a succession of shar impacts of gas against the underside of sai layer of material, and a filter above said la er of material on the hearth for the gas w ich has assed through said material whereby to catc fine dust and allow it to drop back u on the layer on the hearth and means for diawing as throu h the filterwhereby to permit al the gas immediately pass ofi and thereby avoid counter-reactions. 7 Apparatus for the gaseous treatment of finely ivided material com risineg a hearth on which a layer of-fin'ely material i may lie, and means for moving said la er of material un finely divided material along said heart said means comprising upwardly inclined gas-passages and means for imparting through said passages a succession of impacts of gas against the underside of said layer of materialfsaid passages having at least a part so little inclined that the finely divided material will not flow downwardly through said gas passages.

8. Apparatus for the gaseous treatment of finely divided material com risin a hearth on which a layer of finely ivide material may lie, and means for moving said layer of finely divided material along said hearth, said means comprising gas-passages and means for imparting through said passages a succession of impacts of gas against the underside of said la er of material, said gas-passages having a re atively small upward inclination not exceeding 30 whereby Stratification of said der the action of said impacts of gas is prevented.

9. A paratus for the gaseous treatment-of finely ivided material, comprising a hearth on which a layer of said finely divided maward the material on said hearth, separate gas chambers for different portions of said hearth, means for moving said layer of finely divided material along said. hearth compris ing means for imparting a succession of s arp impacts of said inert gas through said chambers against the underside of said layer of material, means for admitting limited uantities of gas reactive toward said material to said chambers, and means for regulatin the amount of said reactive gas admitted to individual chambers. p

10. Apparatus for the gaseous treatment of finely divided material comprising a hearth on which a layer of said finely divided material may lie, a source of gas, separate gas chambers for difierent ortions of said hearth, means for moving said layer of finely divided material along said hearth com rising means for imparting a succession of s arp impacts of said gas through said chambers against the underside of said layer of material and means for individually opening and closing said chambers, said latter means being independent of said means for imparting said impacts.

11. Apparatusfor the gaseous treatment of finely divided material com rising a divided hearth on which said finely material may lie, a source of reducing gas, a heating chamber, pi s for said reducing gas assing through sai heating chamber, means or suphot combustion products to said heaty ing chamber to heat said pipes, and means for supplyin said heated reducin gas and said hot com ustion' products to t e underside of said layer of material on said hearth,

gas and said hot combustion products to the underside of said layer of material on said hearth, whereby said gases may pass through and in intimate contact with said material, and means for admitting regulated quantities of air to combustion products supplied to theunderside of said layer.

13. Apparatus for the gaseous treatment of finely divided material comprising a hearth on which said finely divided material may lie, a source of reducing gas, a heating chamber, pipes for said reducing gas passing through said heating chamber, means for supplyin hot combustion roducts to said heating 0 amber to heat sai pipes, separate earth, and means for conducting said heatterial y a Source of g inactive lgas chambers for dlfierent portions of said t ed reducing gas to selected gas chambers,

and means for conducting said hot combustion roducts to other of said separate gascham ers, and passa es between said chambers and'the undersi e of said-layer of material on'said hearth, whereby said gases may pass through and in intimate contact with said material.

14. Apparatus for the gaseous treatment of finely divided. material, comprising a hearth on which a layer of said fine y divided material is adapted to lie, and throu h which gas is adapted to ass to the undersi e thereof, said hearth eing made in replaceable sections, ducts for conveying as to said hearth and for leading it ofi a er passing through said layer of material, said apparatus having a side wall through which said ducts pass, and another side wall of readily removable construction, permitting of lateral access to said hearth for replacement of sections without necessitating the removal of the side wall or parts thereof containing said ducts.

15. In a furnace for the treatment of ore,

a hearth constructed to permit the passa e of gas thereto, means for projecting u s of gas through said hearth, and a filter a ve the space for the passage of ore over the heart 16. In a furnace for the treatment of ore,' a hearth constructed to permit the passage a perforated hearth, a series of chambers under the same, ducts leading into said chambers, adapted to admit as in pufis simultaneously intosaidehamiers.

18. Ina furnace for the treatment of ores a hearth 'adaptedto permit the passage of gas therethrough, means for supplying a plurality of hot gases of diiferent composition to the underside of said hearth, means for effecting passa e of the hot gases through said hearth and t e ore body thereon, and

- means for (producing variations in the pressure of sai hot gases to produce propelling impulses on the ore body to feed it along said. hearth.

19. In a furnace according to .claim 18, saidhearth having a long chamber beneath the same, and means for admitting gases of different composition to said chamber at different points along said hearth,whereby to effect different chemical actions upon said ore.

20. In a furnace for the treatment of ore,-

a hearth constructed to permit the passa e of i a gas thereto, means for rejecting pu s of aeriform materialthrou said hearth, said means for propulsion o aeriform material comprising means for supplying a plurality of different kinds of such material.

. 21. In a furnace for the treatment of ores, a hearth adapted to permit the passage of a gas therethreugh, means for supplying a hot gas to the underside of said hearth, means for effecting passage of said hot. asthrough said hearth and the ore body t ereon, and means for producing variations in the pressure of said hot gas to produce propelling impulses on the ore body to feed it along said hearth, said latter means comprising a valve made with a sufiiciently loose fit to ermit even when the valve is closed, an e ective gas at all times for the treatment terial comprising feeding said material along. a hearth by impacts of gas. a ainst the underside of said body, said gas inga hot inert 25. Process of treating finely divided material, comprisingfeeding said material along said hearth by impacts of gas against the underside of said body, said gas being an inert gas, and admitting limited quantities of ac-' so as to avoid Stratification 26. Process of treating finely divided ma- I terial, comprising feeding said material along a hearth by impacts of gas a' inst the underside of said body, and with rawin said as from the upperside ofsaid materia where y said gas after passing through said material moves directly-awaiy therefrom, and counter- I reactions prevente 27. Process of treating finely divided material with gases of, different composition, comprising assing gases of difierent composition to 'fierent parts of said material spread out in a layer upon a hearth, and moving said layer of material along said hearth by impacts of said gases against the underside of said material.

28. Process of treating finely divided material with gases of diflerent composition,

comprising position to spread out in a layer upon a hearth, and moving said layer of material along said hearth by impacts of saidases against the underside of said materia ,"said gases being 'principally inert and reducing gases.

piassing gases of different com- 29. Process of treating finely divided ma,

terial with gases of different composition,

fi'eren't parts of said material.

comprising passing gases of difie'rent comj position to different parts of said material spread out in a layer upon a hearth, and moving said layer of material along said hearth by impacts of said gases against the underside of said material, said gases-being principally inert and reducing gases, and admitting ac tive gas to the inert es at different parts of said hearth to e ect desired degrees of oxidation. e

In witness whereof, I have hereunto signed my name.

FRANCIS M. SIMONDS.

tive gas to said material'at different parts of I said hearth.