US2241429A - Method of treating materials - Google Patents

Description

May 13, 1941. B. A. SMITH 2,241,429

METHOD OF TREATING MATERIALS Filed Aug. 14, 1937 2 Sheets-Sheet 1 ATTORNEY6 May 13, 1941. B. A. SMITH METHOD OF TREATING MATERIALS Filed Aug. 14, 1937 2 Sheets-Sheet 2 IIIIIIIIII/ INVENTOR. flea/am! 4.5m c9 0&1

Patented May 13, 1941 METHOD OF TREATING NIATERIALS Benjamin A. Smith, Lakewood, Ohio, assignor to The C. 0. Bartlett & Snow Company, Cleveland, Ohio, a corporation of Ohio Application August 14, 1937, Serial No. 159,140

.2 Claims.

This invention relates, as indicated, to an improved method of the treatment of materials, and this invention particularly relates to a method of the preparation of charges of raw material prior to their introduction into conventional furnaces, usually of the electric type, employed in the manufacture of metallic alloys.

The manufacture, or more particularly, the smelting of metallic alloys, usually accomplished by a reduction of the ore and frequently the smelting therewith of a certain amount of scrap metal, is generally carried on in an electric furnace for the reasons well known in the art. While it is usually necessary and desirable to carry on the final smelting operation under the carefully controlled conditions possible in an electric furnace, it is generally not necessary nor economical to heat the material from its cold state in the electric furnace. If the ingredients or constituents of the final charge can be heated properly up to a temperature below which the carefully controlled conditions existing in the electric furnace are not necessary, then more economical means such as hydrocarbon fuels may be employed to effect such initial heating with a consequent saving in total cost.

It is the principal object of my invention to provide a method by which the above-referred to preliminary heating of the charge constituents may be advantageously and economically effected.

It is a further object of my invention to provide a method of the character described characterized by the fact that the preliminary heating of the raw materials is effected in a most economical manner and in such a way as to insure that the charges supplied to the electric furnace for the final heating, reduction or smelting operation may be uniform as to quantity and quality so as to insure maximum efii ciency of operation of the electric furnace and uniformity of the product produced thereby.

Other objects of my invention will appear as the description proceeds.

I To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims; the annexed drawings and the following description setting forth in detail certain means and one mode illustrating, however, but one of the various ways in which the principle of the invention may be used.

In said annexed drawings:

Fig. 1 is a plan view showing somewhat diagrammatically one form of apparatus capable of carrying out the principles of my invention.

Fig. 2 is a side elevational View, partially in section, of one of the units which comprise the combination illustrated in Fig. 1.

Fig. 3 is a transverse sectional view drawn to an enlarged scale of a portion of the apparatus illustrated in Fig. 1 taken on a plane substantially indicated by the line 3-3.

Fig. 4 is a transverse sectional View of a portion of the structure illustrated in Fig. 3, taken on a plane substantially indicated by the line 44; and

Fig. 5 is a fragmentary sectional view of a portionof the apparatus illustrated in Fig. 3, taken on a plane substantially indicated by the line Broadly stated, this invention comprises a method of the preliminary heating of charges of raw material such as may be introduced into an electric metallurgical furnace characterized in that separate heating kilns are employed for such constituents as it is convenient or desirable to preliminarily heat separately before introduction into the smelting furnace. Such kilns are preferably sufiiciently large in capacity to accommodate a quantity of impounded raw material substantially greater, and for most purposes several times the quantity of, individual charges of the particularly impounded material.

The impounded material may be heated by some relatively inexpensive hydrocarbon fuel and at a substantially uniform rate so that when the impounded material, as it is depleted for the purpose of charging the smelting furnace, is replenished at such a rate as to maintain substantially constant the temperature of the kiln within which the preliminary heating is effected.

Referring now more specifically to the drawings and more especially to Fig. 1, the arrangement here illustrated is a plan view of a conventional installation constructed in accordance with the principles of my invention. The electric furnace or similar smelting furnace, generally indicated at I is of course the smelter or melting device which is to be supplied with charges of raw material by the process and apparatus of my invention. The numeral 2 denotes the location of a crane cab, such crane operating, for example, along the line generally indicated at 3, being capable of readily transporting the raw material constituents comprising the charge which may be introduced, for example, centrally to the smelter I. Positioned in suitably spaced relation with respect to each other and desirably arranged with respect to the line 3 of movement of the crane for the purposes hereinafter more fully explained are a plurality of kilns generally indicated at 4 and 5 respectively. The number of separate kilns employed in a particular installation will depend, of course, upon the nature of the raw material which is being smelted. For purposes of illustration, only two of such kilns have been shown since the principles of my invention apply without substantial modification to an arrangement comprising greater number of such kilns. Throughout the ensuing description it will be assumed, therefore, for the purpose of simplifying this description that the charge to be supplied to the furnace i will consist of two primary constituents, for convenience referred to as the ore and lime. It is assumed, therefore, for purposes of illustration in describingthe invention, that the furnace l is a reduction furnace to be supplied with charges consisting of pre-determined amounts of ore and lime. For the manufacture of more complex metal alloys it may, of course, be desirable, as above pointed out, to maintain as separate units a greater number of the charge constituents requiring the use of a correspondingly greater number of separate kilns.

It is likewise within the contemplation of my invention to employ a single pre-heating kiln into which may be introduced a mixture of all of the ingredients and in the proper proportions required for the charge to the smelter. This may be necessary and desirable where the nature of the charging materials is such that they may be advantageously or desirably pre-heated while 7 character. Each kiln will be provided with an annular driving gear 9 which will be in mesh with a driving pinion and its associated speed reduction mechanism and driving 'motor, not shown. These last-named elements have been omitted from the illustration in order to clarify the drawing. It will be noted, however, that the driving means for the kilns 6 will be capable of selectively driving each kiln in opposite :directions.

Each kiln may be provided with a feed hopper Ill containing the cold rawmaterial which may be fed thereto by any suitable means such as a screw conveyor, generally indicated at H. The hopper H1 may, of course, be supplied with raw material from a bin, generally indicated at 42, and buckets or cars such as 13 may, of-course, be employed for the purpose of conveying the raw material from the bin to the hopper. It is, of course, within the contemplation of my invention to variously arrange the supply of raw material so as to maintain in the hopper Iii an adequate quantity of the same to be fed into the kiln 8 by the feeding device N. If desired, the'feeding device II and its associated hopper ill may be moved on a platform Hi which, mounted on rollers,'rnay be moved to and from the feeding opening in the kiln B. This arrangement permits ready inspection and repair of the various work ing parts, and if desired, the feeding device, genkiln 6 supplied with the necessary quantity of impounded material to be heated in preparation for the charge. In such case the opening through which the material is fed to the kiln 6 may be closed by some removable device which would assist in conserving the heat within the kiln 6.

At the opposite end of the kiln 6 from the feeding device H is a hydrocarbon fuel burner generally indicated at I5 and it is within the contemplation of my invention to employ any suitable fuel in such burner, such as, for example, gas, oil or powdered coal. This burner heats the material internally or directly.

The stack opening from the kiln 6 will preferably be in the same end with the feeding opening, for example, the stack opening may be concentric with the feeding opening, in which case the duct or flue l6 may extend downwardly and lead to the main stack for the plant.

Each kiln 6 will be, at some convenient location preferably adjacent the end occupied by the hydrocarbon burner, provided with a discharge ring, generally indicated at H, the construction and mode of operation of which may be more readily determined by having reference to Figs. 3 to 5.

Referring now to Fig. 3, the outer periphery of the kiln 6 is indicated by the line I8. Within the outer shell the kiln is of course provided with a refractory lining which extends inwardly to the line I9. Arranged in a circumferentially extending groove on the inner periphery of this refractory lining are a plurality of complementary segmental members, generally indicated at 2B.

erally indicated at H, maybe movedinto'feed;

tervalsi as'it is necessary inorder'to'keep the ingre'lation with the kiln 6. during only su'ch ina These segmental members will be of some suitable high-temperature-resistant alloy and substantially rectangular in shape, each providing a short circumferentially extending laterally restricted passage for the flow of material from the interior of the kiln to the outside thereof. One end of each of these segmental units 20 is provided on its inner face with an opening 2! and the opposite ends of these segmental units are respectively provided with outwardly extending throats 22. Th several segmental units are provided with circumferentially extending fingers 23 which, when the several units are assembled in themanner illustrated in Fig. 3 and at their outer ends bolted to the shell of the kiln 6, will look all of these segmental units against displacement. The casing 24 around the kiln 6 in the circumferential area occupied by the segmental units 26 is for the purpose of collecting the material discharged from the kiln, and a suitable spout such as 25 may be provided to carry the discharged material into a car or bucket 26 which will'be supported for convenience on a weighing scale platform 21 by which the quantity. of material discharged for a particular charge may be accurately determined.

It will be observed that when the kiln rotates in the direction indicated by the arrow 28 in Fig. 3 the Y material within the kiln will be scooped up through the openings 2| by the segmental members Zfl and as each segmental member moves to the lowermost position the contents of the passage through such member will be dis charged into the spout 25. If, however, the kiln is rotated in a direction opposite to that of the arrow 28 the material will be prevented from flowing out through the segmental membersand the material which has fallen into the openings 2i will substantially seal the ,same and thus con iefve. the heat and burning gases within the In the operation of the apparatuses above described in carrying out the principles of my invention, the ore and lime, for example, shall go to make up the component parts of the charge for the furnace which will be introduced into the respective kilns 4 and 5. A sufficient quantity of raw material will be maintained in each kiln at all times so as to more than supply the requirements for a single charge for the furnace I. In fact, it will be found desirable in certain instances to impound enough material in each kiln to supply the requirements of several individual charges. Thus, a residual charge of hot material is left in each kiln at all times. When heated material is wanted for the furnace charge the kiln, normally rotated in such a direction as to retain the material therein and to agitate the same so as to insure its being uniformly heated, will be stopped and rotated in the opposite direction. This will result in a discharge of the heated material from the kiln so reversed, and the discharged material will flow into the car 26 where it can be weighed and the rotation of the kiln in the discharging direction stopped when the desired amount of material has been withdrawn. The car 26 will preferably be refractory lined, covered and thermally insulated to preserve the heat of the material therein during the time when the car is transferred by means of the crane or otherwise over to the furnace and its contents charged into the furnace. It will be observed that the discharge point in the kiln is substantially removed from the charging point, and if a sufiicient quantity of raw material is impounded in the kiln it may be entirely feasible to feed the raw material into the kiln at a continuous uniform rate. Thus it is feasible for certain types of material, and where the impounded quantity of raw material is great enough, to continue the feeding of the cold material into the kiln simultaneously with the Withdrawal of hot material therefrom. For certain types of material it may be found desirable to interrupt the feeding of cold material into the kiln for an interval shortly prior to the time when a charge is to be withdrawn from the kiln.

It will be observed from the foregoing description that I have provided a method of and ap para-tus for preliminarily heating the charges for metallurgical furnaces characterized by the fact that this preliminary heating of the raw material may be carried on in a substantially continuous manner so as to utilize to the fullest extent the heat of the preliminary heating medium. Furthermore this process insures the necessary supply at all times of the components of the charge for the furnace and at uniform conditions particularly with respect to temperature; the preliminary heating being accomplished by the use of relatively inexpensive fuel, the process comprising my invention materially reduces the total cost of the smelting operation.

It is further frequently found desirable to accomplish the preliminary heating in an oxidizing atmosphere to the end that free carbonaceous materials contained in the ingredients entering into the furnace charge, may be fully oxidized and converted to gases which pass out of the preheater apparatus thereby greatly assisting the control of carbon in the alloy subsequently produced by the furnace.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the means and the steps herein disclosed, provided those stated by any of the following claims or their equivalent be employed.

I, therefore, particularly point out and distinctly claim as my invention:

1. The method of charging a metallurgical furnace for metal alloy manufacture which comprises separately impounding the reducing and reducible materials in quantities substantially greater than that required for individual charges, heating internally such impounded masses at substantially constant rates while continuously agitating the same, intermittently withdrawing from such impounded masses suflicient of such pre-heated material to constitute a charge for the furnace while continuing the agitation of said mass and replenishing the impounded mass so intermittently depleted by the addition thereto of raw material at such a rate that the temperature of the impounded mass is not substantially changed by the introduction of such raw material.

2. The method of charging a metallurgical furnace for metal alloy manufacture which comprises impounding a charge material in quantities substantially greater than that required for individual charges, heating internally such impounded mass at substantially constant rates while continuously agitating the same, intermittently withdrawing from such impounded mass sufiicient of such preheated material as is required for a charge for the furnace while continuing the agitation of said mass and replenishing the impounded mass so intermittently depleted by the addition thereto of raw material at such a rate that the temperature of the impounded mass is not substantially changed by the introduction of such raw material.

BENJAMIN A. SMITH.

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