US1433348A - Process of treating ores to sinter them - Google Patents

Description

A. S. DWIGHT.

PROCESS OF TREATING ORES T0 SINTER THEM. APPLICATION FILED MAR 14,1912.-

Lfigg 34fi Patent-ed Oat. 24, 1922.

3 SHEETS-SHEET I.

A. s. DWIGHT.

PROCESS OF TREATING ORES T0 SINTER THEM. APPLICATION FILED MAR I4, 1912.

1 %33 34@n Patented 0013. 24, 11922,

K 3 SHEETS-SHEET 2.

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PROCESS OF TREATING ORES T0 SINTER THEM.

APPLICATION FILED MAR 14,19I2.

Patented Oct. 24, 1922.

' 3 SHEETS-SHEET 3.

Fla/mentor Wyn mono antenna s. n renr, or NEW Nona, N. 2:, nssreNon 'ro EWrer a more LURGJECAL COMPANY, or NEW YOR, N. E, a conronn'rroN on NEW ,irE sEv.

PROCESS OF TREATLN'GORES T0 EINTEIR THEM.

' Original application filed December as, 1907, serial Ito. tomato... m nded and an application mm March 1441912. Serial No. M3360.

T 0 all whomit may concern:

Be it known that ll, ARTHUR S. DWIGHT, a citizen of the United States, residing at New York, in the'county of New York and State of New York, have invented certain new and useful Improvements in Processes of Treating Ores to Sinter Them, of which the following is a specification, reference being bad therein to the accompanying.

drawing.

This invention relates to the art of treating ores for the purpose of sintering them, especially such ores as contain or have mixed with them a readily combustible element .or substance and are of such nature that combustion may be carried on therein after an initial i niting of the mass has been efiected; and which may, by reason of the said combustion, be sintered or have the particles thereof agglomerated into masses which are well suited for subsequent treatment in blast furnaces. I may mention as one example of an ore such as the process and apparatus herein to be described are adapted to treat, a sulfid ore in which the combustible constituent, sulfur, is in sufficient quantity to permit the ore to be readily ignited and to burn it supplied with air or other supporter of combustion; and as another example of the material to be treated, I may mention a mixture of pulverized or finely divided ore and pulverized coal or other form of carbon.

The invention herein claimed relates particularly to .the method or process employed for effecting the initial ignition of the ore and maintaining the combustion therein until the entire mass is treated and sintered. The features which constitute the invention herein presented and claimed are capable of being carried out by means of apparatus comprising any of numerous sorts of mechanisms for supporting and for carrying the ore during andafter treatment,and in respect to said supporting and carrying mechanisms the present invention is not limited. For the purpose of illustrating how the invention may be practically carried into effeet, I have represented in the acccompanying drawings, the mechanism for supplying and transporting the ore, and finally delivering it in sintered masses, which is shown, described and claimed in my application for patent filed December 23, 1907 original Serial Number 407 860 on which issued Patent 1,927,110 dated Ma 21, 1912, of which case this application is a division.

In such drawings,.

' ltflgure 1 is a side elevation of an ore sintering machine in which the improvements here n presented and claimed are embodied,

Fig. 2 1s a cross sectional view of one of the pallets, showing adjacent parts of the upper and lower all boxes.

Fig. 3 is a side elevation of one of the pal lets or individual elements of the support and carrier for the ore, in the position .occupied While the ore is being treated, and of parts of the apparatus immediately adjacent thereto. O

Fig. 4 is a vertical transverse sectional view taken on the line IV-TV of Fig. 1.

Fig. 5 is a central lon itudinal section taken on the line V-V of ig. d.

D Fig, 6 is a transverse sectional view of a sinter ng apparatus showing a diiterent means or igniting the ore from .what is shown in the views already described.

.Fig. 7 is a cross sectional view through an apparatus like that represented inlBig. 1 showing the form of burner illustrated in Fig. 6 applied thereto.

In these drawings, A represents an air box suitably supported in a-frame P. Its upper end is open and with it is connected an off-taking duct T. Across the open end of this air box travel the pallets or ore receptacles D constituting the individual ele-, ments of an ore support and carrier. The pallets carry grates which are suitably-supported therein and are of a construction to properly sustain the ore and at the same time permit relatively free passage of air and other gases through them. Each of these pallets, which may be described as an independent receptacle for receiving the ore and holding it while undergoing the sintering operatlons and then being inverted to discharge the sintered mass, is provided with wheels E, preferably four of them, which are attached to the pallet by suitable lugs carrying1 the axles e on which the wheels turn. ach allet is formed with transverse end wall; S connecting the side walls S, so that each grate is surrounded by four walls, forming an open box-like structure. In the form of apparatus herein illustrated the pallets are arranged to be pushed across tilt (tit

the open end of the box A where they are guided and directed by longitudinal tracks F with which the wheels engage.

A indicates an air box or hood supported above the air box A and connected by a pipe or trunk A with a fan A adapted to force air with the desired pressure into the hood A The lower end of the air box or hood A is open, and there is just sufficient space between the opposed open ends of the air boxes A, A for the pallets D to move between them. At the bottom edges of the hood or air box A are filler bars or joint bars B constituting wearing strips which are care fully planed, and with these engage the upper edges of the pallets, which are likewise carefully planed, as they pass along the tracks F. The vertical edges of the pallets, which abut as they come together end to end, are likewise finished so as to make air-tight vertical joints at the ends of the ore carriers Where the individual elements thereof come together. At each end of the air box or hood A is a cut-off plate or dead plate G the under surface of which is flat and coincident with the plane in which are situated the lower faces of the strips B Across these surfaces of the cut-off plates travel the upper sufaces of the pallets, with which they form air-tight joints at the respective ends of the hood or air box A so that air leakage is prevented as the pallets either approach or leave the air box.

At one end of-the apparatus I have 111118- trated means for imparting motion to the ore support and carrier, these consisting of a pair of sprocket wheels, H, H, each of which is so desi ed that its teeth enga e with the wheels F These wheels H serve to push the cars in an end to end series along the track F, and also to elevate them from the lower track F of the apparatus to working position. Curved guides F partially encircle the wheels H and assist in holding the pallets in engagement therewith.

At the end of the apparatus opposite the wheels H the tracks F are curved downwardly, as indicated at F, and opposite these tracks are concentrically arranged guide rails F These operate to direct the pallets individually from the upper track F to the lower return track F K designates a hopper for feedii g the ore to be treated to the carrier. The character of this feeder is not essential to the present invention. It is represented as being located just in advance of the cut-off plate Gr at the head end of the apparatus. It operates to deliver to each pallet or ore support D a thin bed of ore which is supported by the perforate grate C. The thickness of the bed of ore is such that the air which is supplied under pressure to the hood A readily passes therefrom transversely through the of the cars or pallets layer or bed of ore and into the air box A, whence it escapes, mingled with the prod ucts of combustion and chemical reactions that are incident to the treatment which the ore is undergoing, through off-take duct T.

I have, in the application of which this case is a division, fully described and explained that instead of employing air forcing apparatus to cause air currents to pass downwardly through the ore, use may be made of air suction apparatus for the same purpose.

In the sintering of ore according to the method of procedure herein described, it is common practice to ignite the ore at one of its surfaces, and after such ignition to complete the suitering by combustion carried on within the body of ore and accelerated by transversely moving currents of air passing through the body of ore.

According to my present invention the surface ignition of the ore is effected by the use of an igniter located within the hood A preferably near the end thereof adjacent to the feed hopper K. Any one of a number of forms of igniter may be employed.

In Figs. 1, 4 and 5 of the drawings, I have illustrated an igniter adapted to sustain burning solid fuel and s0 arranged with reference to the surface of the ore as to deliver the hot products of combustion therefrom directly to a relatively broad surface of the ore. The igniting apparatus illustrated in these views is a brazier or small open furnace especially adapted for burning charcoal, coke or similar readily combustible solid fuel. In the bottom of this brazier is located a perforated screen L that supports the charge of fuel which it carries. The charcoal or other fuel within the holder L being ignited, the hot gases of combustion therefrom are carried downwardly by the general direction of air movement within the air box or hood A and are brought into contact with the ore, igniting it. As the charcoal or other fuel burns the ashes drop through the perforate screen and are carried off with the ore being treated.

In Figs. 6 and 7 I have illustrated a form of igniter that may be used in place of the igniter L and which is adapted for burning gasolene, naptha, petroleum or other similar hydro-carbon or combustible fluid. It consists of a pair of spray burners I, preferably located diametrically opposite each other above the edges of the bed of ore and so disposed that the flaming particles of burning fuel proceeding therefrom are applied to and caused to pass over and across the upper exposed surface of a relatively wide and extended area of the ore bed. The burners are supplied with fuel through a pipe I connected with any suitable source of supply and are provided with regulating valves 71.

raaaaae I have not in the drawings illustrated in detail the construction of the spray burners I, as they may be of any well known kind adapted to the use described, as for instance such a burner as illustrated in U. S. Patent 516,928 of March 20, 18st. In order to permit the igniter to be inspected during the operation of the machine, I form windows of mica in the sides of the air box, as indicated at a. The igniter may be lighted throu h a valved aperture in the wall of the air ox or hood, such as indicated at a. a

It will be apparent that in using either form of ignitln apparatus herein illustrated and descri ed, ,a wide area of the ore is at one and the same instant of time subjected to the igniting action of the hot gases of combustion or the flaming particles of matter in combustion, such igniting prod ucts and particles being, by the action of the currents of air which are caused to transversely pass through the ore mass, drawn into contact with the surface of the ore and somewhat into the body thereof. In these respects the igniters herein described and The igniting apparatus herein illustrated possesses the advantage of subjecting acomparatively large area of the exposed body of ore simultaneously to ignition so that it is possible to insure a direct initial ignition of the entire surface notwithstanding the fact that certain areas thereof may be difiicult of ignition owing to a local deficiency in the combustible element of the mass, and which actually fail to become ignited when subjected to only amomentary or a very brief application of the igniting products.

- Again, by locating the 1gniter within the hood A instead of having it in the open as represented in my aforesaid patent, I guard against the waste of heat incident to the igniting flames or products of combustion being carried away from direct con tact with the ore surface by currents of air sweeping transversely across the surface of the ore as is liable when the igniter is located in the open.

In using the apparatus shown the ore carrier is slowly moved and the pallets or individual elements thereof are filled from the hopper K. The air moving mechanism causes a to pass transversely downwardly through the ore upon the carrier. After the ore has been thoroughly ignited at the surface, in the mannerherein described, an

pallet has taken place at about the time, or

shortly before, it arrives at the place where it leaves the air boxes A, A Shortl thereafter the pallet comes to the curve downwardly inclined portion F of the track. whereupon its motion is accelerated and it is inverted, causing a separation of the" sintered mass from the pallet and the grate which it carries, and its discharge.

It will be seen, especially by reference to Figs. 2 and '3 of the drawings, that each holder for a mass of ore to be treated is box-like in construction, being open at the top and having a perforated grate or support for the mass of ore material and with four gas-tight walls at the edges of the mass. The grate is preferably arranged so as to divide the box-like ore support into two chambers, in the upper one of which is deposited the layer or stratum of ore, while the lower one serves as an air or gas chamher, having connection with the off-take duct, T, through the intermediate air box A. With an ore holder of this character and construction, the hood or air box A has temporary gas-tight connection, as has been explained. It is a matter of greater difiicultyto remove the cakes or blocks of sintered ore from a holder having side walls around all its edges, such as described, than from an open ended support such as I have indicated in my aforesaid application of which this case is a division; but this removal can be conveniently and practically eflected by tilting or inverting the holder, as provided for in the apparatus herein 11o illustrated, such tilting or inverting serving not only to separate the mass from the gastight confining walls of the holder, but also loosening and separating it from the perforated grate, the perforations in which are well cleaned as the sintered mass falls away from the holder.

In practicing the process herein described which is for the sintering or agglomerating of metalliferous substances originally in a v pulverulent or fine condition, there are two functionally distinct steps: First, the igniting of the ore, that is, setting fire to the combustible component of the mass of material being treateda step that under favorable conditions requires but little time; and,isec 0nd, the sintering of the mass by internal combustion taking place therein rfiider the influence of air currents passingothrough the mass, which second step usually requires a much longer period to perform than does the ignitin step, and which must be carried on while t e particles of the mass are in a relatively quiescent state with reference to each other in order that the agglomerating or coalescing of the metallurgical particles to form a coherent mass may successfully take place.

In this respect the process of the present invention differs from the ordinary process of roasting ores, or other materlals in a reverberatory furnace where the roasting or calcining operations result from the flames or highly heated products of combustion which are caused to pass through the furnace.

It is important that the igniting step of the process should be thoroughly performed in order to effect a uniform ignition of the entire surface of the mass and this I have found is better accomplished when it takes place within a chamber that tightly closes or covers the body of material being ignited, into which chamber is a free admission or fiow of air or other combustion-supporting gas, as such chamber tends to prevent the dissi ation of the heat from the igniter and enab es it to be applied and directed in a manner to secure the best results.

I do not in this application claim the mechanism for supporting and conveying the ore and for causin air currents to pass through the ore whi e being supported and conveyed which is illustrated and described in this application, as such apparatus is claimed in my aforesaid application filed December 23, 1907, original Serial Number 407,860, of which this case is a division. The said mechanism, in so far as it is a conveying apparatus capable of use for other purposes than in the roasting, sintering and similar treatment of ore, is also claimed by me in my application filed April 30, 1910, Serial No. 558,621, on which issued Patent 1,027,111 of May 21, 1912. And I do not herein claim the mechanism shown in Fig. 1 of this application comprising perforated supports for the ore, the air box or hood covering the same, means for passing air through the material while covered by the hood, and an igniter arranged within the hood, as such subject matter is presented and claimed by me in my application No. 695,883 filed May 8, 1912 as a division of this case, and therefore as a division also of my-aforesaid application 407,860.

Neither do I herein claim the specific form of igniting mechanism illustrated in Figs. 6 and 7 of this case, as this is made the subject of another application which I have made as a division of m aforesaid application 407,860, bearing filed March 25, 1912; nor the process of sintering a thin bed of ore by igniting a wide area of the surface thereof at one and erial No. 685,909,

the same instant of time by a broad mass of flaming particles such as is produced by the igniting means illustrated in Figs. 6 and 7 hereof, and then sintering or agglomerating the mass, as this subject matter is presented and claimed by me in my application 695,- 882, filed May 8, 1912, which is also a division of my application 407,860.

Nor do I herein claim specific form of igniter illustrated in detail in Figs. 4 and 5, as this forms the subject of another application which I have made as a division of my application 407,860, bearing Serial No. 685,910, filed March 25, 1912; nor do I herein claim the process or method of sintering or agglomerating metalliferous substances which are initially in a fine condition, which consists in igniting the same by applying to a broad area of the upper surface thereof a laterally defined body of flame or other igniting material and then sintering by internal combustion carried on within and through the mass of material, as this subject matter is presented and claimed by me in anapplication filed May 20, 1912, Serial No. 698,467, also as a division of my aforesaid application $07,860.

What I claim is 1. The herein described method of treatin fine metal bearing ore carrying a combustible constituent, it consistin in arranging the ore mass in a relatively thin stratum permeable to gases, confining the stratum gas-tight around its edges, enclosing the space immediately above the top surface of the ore stratum by a chamber gas-tight with reference to the ore stratum and its support, causing surface ignition of the ore stratum within the chamber near one end thereof, supplying air to the chamber and causing it to pass transversely through the ore stratum, moving the ore stratum gradually under the said chamber whereby the ore stratum is first i nited at its surface, and thereafter interna combustion is carried on through it apart from and beyond the zone of ignition, and finallv'removing the sintered material from the ho der.

2. The process described in claim 1 when the air supplied to the chamber above the ore stratum is at a pressure above atmospheric.

3. The process described in claim 1 wherein the stratum of ore is divided into separate masses each in gas-tight relationship to the masses on either side thereof, which masses are successively passed below the gas chamber.

In testimony whereof I ailix my signature, in presence of two witnesses.

ARTHUR S. DWIGHT.

Witnesses:

RICHARD L. LLoYD, LOUIS H. HYDE.

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