US1642359A - Electric furnace - Google Patents

Description

Sept. 13, 1927.

D. CROESE ELECTRIC FURNACE Filed Dec. 1, 1926 2 Sheets-Sheet 1 i'L'f T79 2 1 I 4% w N I L.

, If 4 m 1 4 gntghkkgj 13. 1927. D CROESE 1,642,359

ELECTRIC FURNACE vFiledDec 1, 1925 2 Sheets-Sheet 2 i 4 w I: 22 L 25 20 Patented Sept 13, 1927 UNITEi) STATES PATENT orrica.

DIRK CROESE, OE LONDON, ENGLAND.

' ELECTRIC, FURNACE.

Application filed December 1, 1926, Serial No. 152,020, and in Great Britain August, 1995.

This invention relates to the manufacture of metals and alloys from finely divided mineral substances and has particular reference to the production or. reduction of metals from their ores in the electric furnace.

' The object of the present invention is to of the furnace.-

provide an improved method of and means Figure 2 is a vertical sectional elevation forthe electric treatment of metal bearing substances a finel which will ehable SllCl substances as ironsand to be treated for the production of metal on a commercial scale.

A ccording.to the invention a process is provided for the reduction of metal or allo from finely divided ores such as ironsan such process consisting in the removal of impurities, in causing the concentrated material to fallby gravity through a furnace divided into chambers in which the falling material is first preheated and is then caused to pass successively freely through a number of electric arcs under non-oxidizing conditions for the purpose of melting and reduction and in which further heat treatment is finally applied to facilitate separation of metal from slag.

The invention may be carried into effect in an electric furnace comprising a preheating chamber and a series of arc chambers through which the material to be treated falls freely b gravity, -each arc chamber being provide with means to break up the fallin material and deflect it on to the next are 0 the series. The deflecting means preferably comprise a double cone of carbon dis d near the base of thearc chamber WhlCll tapers towards an outlet at its lower endand at the base of the series of chamhers is disposed a heated crucible adapted to be tilted relatively to the upper part of the furnace or retort for the purpose of discharging molten metal or slag. Both retort and crucible are provided with means for preventing ingress of air during normal operation and whilst discharging. and in order to render the reduction to metal as complete as possible thecrucible may be heated by electric arcs in con'unction with a. rotary. or otherwise mova le magnetic field to ensure that the action of the arcs is made effective in every. part of the crucible. Alternatively, the ases evolved by the reaction which takes ace in the furnace and which are normal y discharged to at- .mosphere or employed for power production may be utilized for'heating the crucible.

divided state and the furnace walls to Reference will now be madeto the accompanyiug drawin of example an el the invention into effect and in which-:-

Figure 1 is a vertical sectional elevation of a tilting crucible adapted to be employed in conjunction with the furnace shown in Fi re 1 and the crucible shown in Figure 2.

which illustrate by way" ectric furnace for carrying The electric furnace 1 is of tubular form and com rises at the topa feed hopper 2 from the use of which a conveyor- 3 removes the material to be treated to an inlet4 disposed centrally at the top of the furnace l, the conveyor 3 and inlet 4 being. suitably housed within a casing 5to prevent entry of air at the top of the furnace and avoid oxidization of the material under treatment The incoming material which falls from the Inlet passage 4 meets a conical bafiie 6, the object of which is to break up and distribute the incoming finely divided material towards nevent it assing too rapidly through the urnace and thus partially escaping treatment by the electric area as hereinafter described. The conical baflle 6 is disposed ccntrall within a pr'eheating chamber 7 such baiile forming part of a double conical element supported on arms 8 projecting inwardly from a lining element 9 which forms the base of the preheating chamber and which ta rs internally towards an outlet 10 at its hiss. The elements 6, 8 and 9 are formed from graphite or like material and are mounted in a lining of firebrick or like material 11 which forms the wall of the furnace and is enclosed by an outer sheathing of metal.

The upper or pre-heating'chamber 7 of a the furnace communicates tnrough the outtheir height; witli 2. number of ins ection doors fitted over openings la'and pre erably provided with transparent portions for sighting whilst each electrode chamber 12 is provided with a cleaning door fitted over an opening 15, the dooraof openings 14 and 15 being luted with fire clay or hermetically sealed 1n some'other manner prior to the furnace being set in operation.

The lowermost electrode chamber 12 is notprovided with a tapered. base but communicates directly with a crucible 16 disposed immediately below'the base of the furnace, this crucible being arranged so that the metal can separate from the slag and two or more separate outlets 17 and 18 are provided to enable the molten material to be withdrawn, these openings being normally closed by counterbalanced sliding doors 19. The upper ortion 20 of the crucible is of the same iameter as the lowermost electrode chamber 12 and the engagement between the two is by means of a air of curved co-operatingsurfaces 21 WlllCl'l permit the curcible to be tilted for the purpose of discharging. Whilst the furnace is in operation the base of the lowermost electrode chamber and the portion 20 of the crucible are coupled by means of a sleeve 22 which can be raised when it is desired to tilt the crucible. The crucible 16 is provided with openings 23 at each side which enable three pairs of electrodes to be mounted within the crucible, this number being variable accordin to requirements in order to impart fina treatment to the molten material which collects in the crucible. This final treatment may be conducted independently of the vertical furnace and dampers 24 and 25 slidably mounted in the base of the lowermost electrode chamber and in the portion 20 of the crucible respectively may be provided to cut off communication between the vertical electrode chambers 12 and the crucible 16 when such final treatment is in progress. Beneath the crucible a framework 26 is provided to permit an eleetromagnet bein mounted at this point for the purpose 0 attracting the arcs towards the surface of the molten material collectin on the hearth 27 within the crucible and his electromag net may be so arranged as to produce a rotating or otherwise movable magnetic field in order to ensure that the heating efiect of the arcs is carried to every part of the material collecting in the crucible.

The tilting mechanism for the crucible comprises a hand wheel 28 (see Figure 3) mounted on a spindle 29 and operating a worm 3O meshing with a worm wheel 31 with which a spur wheel 32 is co-axially mounted. The spur wheel 32 engages a toothed sector 33 fixed to the side of the crucible 16 and provided with a plane surface 34 struck from the same centre as the 3 tion of metal.

toothed sector 33 but engaged by friction rollers 35 for the pur se of braki the movement of the cruci le when it is ing moved towards the discharging position.

The furnace is provided with outlets 36 for waste gases such outlets communicating with chimneys 37 as shown in Figure 1.

The ore to be treated is reduced to a finely divided condition by grinding or crushin and if irousand is the substance to be treat it is subject to a preliminar operation to remove -impurities prefera ly. by passa through a magnetic separating device. TE: process is then eontinued in the furnace above described in the following manner The finely divided metal bearing material falls in a continuous stream from the inlet 4 into the furnace 1, the internal arrangement of which ensures that the falli particles are exposed to the heat generate by the arcs at the electrodes 13 for the len of time necessary to effect complete meltin and reduction of all the material passe through the furnace. Whereas the melting point of titaniferous ironsand for example is about 1500 C. and the temperature of the electric arc is over 3000 C. it follows thatwhen ironsand is treated these particles will be completely melted and reduced by passage throu h the arcs, the arrangement of which in addition to the construction of the furnace preclude the formation of a fused mass of material which has been an'obstacle hitherto to the employment of the electric furnace in treating ironsand for the produc- It is to be noted that the uppermost chamber 7 contains no electrodes but becomes heated to the degree necessary to preheat the falling material by part of the ases which ascend from the reaction which takes place in the electrode chambers. The material resulting from the treatment in the furnace 1 collects in the crucible 16 where waste substances suchas silica, lime and sulphur or lect. in a layer a ove the layers of titanium and iron or steel. The-waste gases from the reactiontaking place'within the furnace pass upwardly through the-descending material and are withdrawn at a oint below the preheating chamber throu g the outlets 36 and chimneys 37, part of t ese gases,'however, circulating through the chamber 7 before escaping.

In an alternative arrangement the gas outlet conduit may pass to the base of the furnace where a raft of air is introduced and the gas burnt around the crucible 16 to maintain the contents thereof in a molten condition, this arrangement being employed as an alternative or in addition to the use of electrodes within the crucibleas above de 'scribedh If desired resistance heating may also be employed in addition to or place of the aforesaid methods of heating the phosphorus compounds col- I gas may be passed into storage for use in operating a prime mover and an electricity generating plant.

The preheating chamber 7 may be heated electrically by elements disposed externally or interiially thereof.

The conical elements 6 are preferably supported by four members 8 arranged at ri ht angles one to the other so that the falling material is, alternatively diverted into four streams and re-united in theontlet passages 10 so that a thorough separation of the ma terial is obtained as it ails through each stage of the furnace ensuring that every particle-receives the full influence of the electric arcs. The coned bailles also have the efl'ect of preventing clogging of the material and also of preventing the material passing too ra i'dly through the furnace.

en ironsand or other material containing or consisting of metallic oxide is under treatment it.may be mixed with a quantity of.coke, an hrac te,- or other reducing agent before it is introduced to' the feed hopper 2 or such reducing agent may be introduced to the crucible 16.

"The treatment of ironsand by the process and in the furnace above described enables pure metal to be withdrawn from the crucile-16 through one of its outlets, and titanium slag at the other outlet, the metal being a titanium steel alloy in which the percentage of'titanium varies according to the length of time the treated material is maintained in a molten condition in the crucible. been found that some of the titanium always goes into the slag which has thus various industrial applicatiousjbut by continued heating the titanium contents of the alloy can be reduced to less than 1 per cent producing the best quality titanium steel. if desired the process above described may be carried out in an inert atmosphere. and for this purpose an inert gas would he introduced near the base of the lowermost electrode chamber 12.

The invention is not liu'iited to any particular disposition of the electrodes within each chamber 12 as the electrodes in one chamber may be disposed at a i'litlerent angle relatively to those in the chamber above or below or several pairs of electrodes may be dis osed in each chamber.

laims: 1. An electric furnace for the. production of metals from their ores comprising a ver- It has each chamber, a crucible in which the pro-- ducts from the retort collect, means for heating said crucible and-means for preventingingress of air to said crucible and retort.

2. An electric furnace for the production of metals from their ores compris' a vertical retortidivided into separate c ambers by means of a number of double conical carbon baflles each of which cooperates with a downwardly tapering, throat of'similar material, the upper chamber serving for preheating a stream of freely falling material and the other chambers as are chambers the base of said retort discharging into a heated crucible adapted to be tilt for the purpose of discharging molten me al and slag therefrom.

3. -An electric arc furnace for treating finely d vided ores comprising a preheatin chamber, a series of arc chambers disposed vertically beneath said preheating chamber, a base to each arc chamber comprising an inwardly tapering portion having inwardly directed members which support a double conical ballle concentrically with the chamber and form a number of passages through which the material deflected by the bafile is caused to pass, means for feeding material to be treated to the top of said reheatin chamber so as to fall by gravity t rough al of said chambers. and a heated crucible adapted to receive the material treated in said chambers.

4. An electric arc furnace for treating finely divided ores comprising a preheatin chamber, a series of arc chambers dispose vertically beneath said preheatin chamber, means for feeding material to said reheating chamber in such a manner that t e'operation is carried out under non-oxidizing conditions, a base to each arc chamber comprising an inwardly tapering portion having inwardly directed members which sup rt 8. double conical nntlle concentrically with the arc chamber and form a number of passages through which the. material deflected by the bafile is caused to pass by gravity to the next succeeding chamber. a heated crucible at the base of said furnace, means for shutting off the crucible from the furnace, and means for tilting the crucible for discharging purposes.

In witness whereof I affix I11? si nature.

DIR cfionsa.

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