US1322143A - Assionobs to the new jebsey zinc - Google Patents

Description

J. A. SINGMASTER, F. G. BREYE'R AND E. H. BUNCE. PRODUCTION OT METAL Ox|DS AND OTHER COMPOUNDS oF METALS.

APPLICATION FILED JULY 22.1919.

Patented Nov. 18, 1919.

3 SHEETS-SHEET l.

wuemtos (1R04/nego J. MA. SINGIVIASTER, F. G. BREYER AND E. H.- BUNCE.

PRODUCTION 0F METAL OXIDS AND OTHER COMPOUNDS 0F METALS. APPLICATTON HLED JULY 22.1919.

1,322, 14.3. Patented Nov. 18, 1919.

` 3 SHEETS-SHEET 2T L-A. SINGMASTER, F. G. BREYER AND E. H. BUNCE. PRODUCTION OF METAL OXTDS AND OTHER COMPOUNDS 0F METALS. APPLICATION FILED JULY 22.1919.

1,322, 14:3. Patented Nov. 18, 1919.

3 SHEETS-SHEET 3- UNITED sTATEs PATENT oEEicE.

BUNCE, 'PALMERTON, PENNSYLVANIA, ASSIGNORS TO THE NEW JERSEY .ZINC COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

PRODCTION OF METAL OXIDS AN D- OTHER COMPOUNDS OF METALS.

To all whom 'it may concern:

Be it known that we, JAMES A. SINGMAsTEn, residing at New York` city, county and State of New` York, FRANK G. BREYER and EARL H. BUNGE, vboth residing at Palmerton, county of Carbon, State of Pennsylvania, have invented certain new and useful Improveinents in the Production of Metal Oxids and other Compounds of Metals (Case F g) and we do hereby declare the f ollowing to be a full, clear, and exact description of the invention7 such as will enable others skilled in thel art to which it appertains to make and use the same.

This invention relates to the production of metal oxids or other compounds of metals volatilized by the Wetherill process, and has for its object the provision of an improved method of producing metal oxids, or other compounds of' metals volatilized by the Wetherill process in a continuous operation, as well as the provision of an improved aparatus for carrying out the method of the invention.`

Metallic oxids,"such, for example, as zinc oxid and leaded zinc oxid, as well as other compounds of metals volatilized by the Wetherill process, such for example, as basic lead sulfate or sublimed lead, have heretofore been more or less extensively produced by the so-called Vletherill process. In speaking of metals volatilized by the Weth- 'erill process,'we intend to describe and cover such metals asare volatilizable at the temperatures attainable in the Wetherill process, and, for the sake of brevity, we shall hereinafter designate these metals as volatilizable metals. In the case of certain of such metals, the final or desired compound or compounds thereof are the result of 'a sequence of actions in which the metalliferous materials of the charge are reduced, the reduced metal volatilized .and`then oxidized or otherwise compounded, while in other cases a metal compound maybe directly volatilized, with or without subsequent oxidation or compounding. c

By the expression Wetherill process,

'as we have used the Same herein, 1s to be understood the furnacing step of the process for producing metal oxids or other compounds of volatilizable metals in which a charge of the metalliferous material mixed with a reducing agent and spread on an Specilcation of Letters Patent.

Y Application mea my 22, i919. serial ne. 312,568.

lignited bed of fuel is subjectedl to a combustion su orting blast or draft and brought to a su ciently high temperature to `reduce the metalliferous materials and volatilize the reduced metal or metals (and (or) to volatilize a metal or a metalcompound or compounds) without bringing the charge 'to' a condition where it 'becomes impervious to 4 i the blastor draft, the entire charge being supported on a furnace hearth or grate designed to hold it without letting any considerable part drop through, and the worked-off material bein 'discharged as a clinker or sinter, The urnacing step .is

independent of the subsequent treatment of the laden furnace gases and of the collection of the metal compound or. compounds.

As a typical example of the Wetherill process, as heretofore usually practised, we

will briefly describe the customary procedure in the commercial production of zinc oxid, including leaded zinc oxid. The furnacingl step is generally carried out in a furnace having a broad expanse of horizontal grate or hearth roofed over with an arch, and associated with appropriate instrumentalities for permitting the passage therethrough and into the charge, by either.J A

a blast or draft, of a combustion supporting gas. It is customary to first charge upon the furnace grate or hearth a layer of buckwhea-t anthracite coal `(which is thereupon ignited usually 'by the residual heat of the furnace) and by means of a forced blast or draft of air to bring this initial layer of coal to well-developed combustioii. Upon this layer of bed coal is then charged the customary mixture or working charge characteristic of the Wetherill process, that is to say, a mixture of finely divided reducing coal with the finely divided zinkiferous (or zinkiferous and plumbiferous) material, such as zinc silicate, roasted zinc blends, roasted so called mixed sulfide of zinc and lead, spelter retort residues, or other reducible zinc-containing or'zincand lead-containing material at the disposal of the operator. The

forced air draft is continued, and, when the.

familiar flames of greenish tint,known as zinc candles,7 begin to make their a pearance above the'upper surface of the c arge, indicating that the reduction and volatiliza tion of the zinc and its oxidation to .the

form of fume is well under way, the products of combustion carr in the zinc oxid fume and other volatihze 4metallic compounds are conveyed through the customary cooling flues, etc., to the bag-room wherein, in a cooled condition, they filter through the 'bags and pass ofi into the atmosphere, leaving the fume collected in the interior of the bags, from which it is removed at convenient intervals. The furnace operation is continued until the production of fume therefrom in appreciable quantity ceases, whereupon the residualcharge, which is, to a large extent, sintered together, is broken up by long-handled rabbles and pried up and lifted or scraped out through the furnace doors into a receiving pit, or the like, preparatory to the starting of a new operation. The coal or other carbonaceous material of the charge serves the two-fold purpose of furnishing a reducing agent for effecting the reduction of the metalllferous materials of the charge and of furnishing, by combustion, the necessary degree of h eat to bring these materials to the reduclng temperature characteristic of the process.

As thus ordinarily practised, the above described furnace operation is attended with certain defects interfering with its full eiiiciency. Prominent among these defects is the inevitable tendency to the formation of blow-holes or craters at various regions of the charge. Working or rabbling of the charge to break up these blow holes involves considerable labor, and in addition the formation of blow-holes causes waste of fuel and ineiiciency in the recovery of values. A further defectof the above described furnace operation is that the forced draft tends to project into the free space above the charge more or less dust, and this dusting is further aggravated by the rabbling operations. This dust contaminates the fume and damages its color and marketability. These and many of the other de-fects of the above described furnace operation as heretofore generally practised are overcome to a very remarkable extent by modifying the heretofore customary practice in accordance with the improvements described in the application for Letters Patent-of the United States of Frank G. Breyer, James A. Singmaster and Albert E. Hall, Ser. No. 270,179, filed January 8, 1919. These improvements consist in supplying either or both the bedfuel and the working charge to the furnace hearth in the form of briquets. The improved results attendant upon this modication in the prior customary practice are described indetail in the aforementioned application.

In commercial practice, the furnace in which the Wetherill process is carried out has heretofore` been generally constructed as a block containing several grate units. Thus, vit is customary to buildthe furnace or block with four to twelve .grate units, each of which may, for example, be about four feet wide and about ten feet long. These grate units may be arranged side by side, or half 0f -the grate units may be arranged side by side and the two halves arranged back to back. The purpose of this arrangement is t0 get relative continuity of action in the treatment of charges that individually are Worked intermittently. Thus, while the operation of the furnace or block may, for practical purposes, be considered more or less continuous, the operation with respect to any individual grate unit is intermittent.

One of us, James A. Singmaster, has described and claimed in U. S. Letters Patent Nos. 1,112,853 and 1,112,854, patented Oct. 6, 1914, a process and apparatus for producing sublimed metallic products by the Wetherill process in which the ignited charge is advanced through a suitable combustion zone in a continuous manner. One of the dificultiesl encountered in attempting to advance through a combustion zone a charge of finely-divided materials, such as the heretofore customary Wetherill process charge, supported on a movable perforated grate, is that of providing a seal at the sides of the charge. The relative motion between the side walls of the combustion zone andl the moving charge provides a very susceptible region for the air blast to break through the charge, and because of this relative' movement it is practically impossible to provide an effective seal between the moving charge and the stationary furnace walls with which it directly contacts. In the aforementioned Letters Patent this diiiiculty is avoided by supporting the charge during its movement through the combustion zone on grate sections so arranged that the moving charge is not in contact. with" any stationary element, the grate sections themselves being designed to effect the desired seal between the movable and stationary parts.

We have now discovered that very remarkable results are attained, when the Wetherill process is carried out as a continuous operation by advancing an ignited working charge through a suitable combustion zone, by supplying to the moving furnace hearth either or both the layer of bed fuel and the working charge in the form of briquets. The present invention thus contemplates advancin through a suitable combustion zone a Worling charge containing a briqueted mixture of metalliferous material and a reducing agent spread on an ignited layer of bed fuel, also preferably in the form of briquets, and simultaneously passing a combustion supporting gas into the charge.

In our preferred practice, the working charge, 1n the form of briquets made up of buckwheat size,

-the form of briquets, j supported on a perforated furnace hearth, 1s

advanced through compressin working charge as a mixture of metalliferous materials, such, for example, as zinkiferous, or plumbiferous, Aor plumbiferous-zinkiferous material and an appropriate reducing agent, is s rea upon a well ignited layer o bed fuel a so in and the entire charge,

a suitable combustion 'zone or chamber. The fuel briquets may', if desired, contain such a metalliferous material as will not interfere with their normal function. Y

The bed fuel briquetsnay be prepared by finely divided coal, together with a suita le binder, such, for example, as

-the concentrated waste sulfite liquor of the sulfte paper pulpl industry. Various forms and grades of carbonaceous material are available for the bed fuel briquets. Thus, for example,

such as No. 4 buckwheat, .colliery washing, dirt coal, dust coal, as 'well as coke breeze, may be utilized in the production of the bed fuel briquets. The bed fuel briquets are of such size and shape as to materially reduce the resistance to the combustion supporting gas, and nevertheless to supply such a substantially uniform substratum for the support of the superposed to give free access therethrough and practically equal distribution thereto of the combustion supporting gas. To this end, the bed fuel briquets, as well. as the working charge briquets, should be of substantially uniform size, and preferablv of such shape that they roller tumble easily over one another. Thus, we have found the so-called pillow block, eggette, rounded pillow block, over-stuifed pillow, and similar shapes well suited to the purposes of the invention.

While the working charge consisting of a mixture of the metalliferous material and queted. However,

' an appropriate reducing'agent may be supplied to the ignited layer of bed fuel briquets in an unbriqueted form, we prefer to briquetthe working charge because of the many attendant advantages. Furthermore, we wish it to be understood that the inetalliferous .material may be briqueted alone, without briqueting the reducing agent, or the reducing agent may be briqueted alone without briqueting the metalli'ferous material or the reducing agent and the Inetalliferous material may be separately briour preferred practice is to briquet a mixture of the metalliferous material and the reducing agent.

The reducing agent of the working'charge may be of any suitable kind, and while we now prefer to employ carbonaceous material as the reducing agent, it will be understood by thosev skilled in the art that reducing agents other than carbonaceous materials are available for the purposes of the invention.

,coal of finer mesh percentage of' the application Singma anthracite coal below the No. 3

One -of the'advantages of emplo ing a briquetedl reducing agent in any o the forms hereinbefore described is that it permits the use of carbonaceous materials of cheaper grades and finer `mesh, such as anthracite than No. 3 buckwheat, colliery washings, dust coal, coke breeze and thelike. gj, l The bedfuelfbriquets and the working charge briquets may be. prepared l procedure escribedz inlv lthe [aforementioned '-of'Frank1-GBreyer, J amesl A, ster-and .'Albe'rtE. Hall, Serial No. 270,179,- for prepar g @similar vfuel and working charge. ri `nets welliulapted for the purposesof ourl present invention. This procedure involves-'generallyvthe steps of mixing the material-toghe briqueted with a suitable binder, suchas concentrated waste sulfite liquor of 309v Baume, molding the mixture into briquets of the desiredsize and shape, and dryingv or baking the briquets at.

a temperature of approximately 200 C., so as to impart to them'tlie desirable amount of resistance to crumbling and breaking so that they may be freely subjected to the rough handling incident to storing them, conveying them to the furnace, and incident to charging them into the furnace either by hand or otherwise. In the case of the briqueted metalliferous material, it is also desirable that the briquets possess such resistance to crumbling and breaking, as to substantially maintain their form during the entire furnacing operation,'so that they are for `the greater part discharged from the furnace in substantially their original physical form. The remaining novel features of the invention can be best explained by reference to the accompanying drawings, in which Figure l is a=sectional eleva-tion of `our improved furnace structure; -Fig. 2 is a'side elevation of the same; Fig. 3 is a top plan of the furnace; Figs.- 4, 5 and 6 are sectional views taken on the section lines 4-4, 5--5 and 6 6, respectively; Fig. 7 is a sectional view of the water-cooled leveler for the briqueted working charge, and Fig. 8 is a d'etail view of Ithe perforated furnace hearth.

The furnacev illustrated in the drawings has a movable or traveling hearth 10 in the form of a continuous @belt or conveyer. ,The furnace hearth may advantageously be of the general design used. in mechanical stokers. As thus constructed, the hearth is made up of a plurality of grate sections secured at their ends to sprocket chains 11. Each grate section is composed of a rigid frame piece having a which are strung or keyed the relatively narrow members 12. The members 12 while mechanically contacting with one another permit the passage of the combustion supporting gas therebetween. The spaces be- 11? any, appropriate 'mannengff-'Wc have found the dove-tailed web on tweenl adjacentgrate sections and between adjacent members 12 of each grate sectlon provide perforations or small passages uniformly distributed over the entire area of the hearth. r

The two sprocket chains 11 cooperate with and are driven by sprocket wheels 13 and 14 secured to shafts 15 and 16, respectively, at opposite ends of the furnace. The shafts l5 and 16 are connected through similar wormreduction drives 17 and 18, beveled gears 19 and 20 21 and 22, respectively, to a common shaft 23. The shaft 23 may be driven from any suitable power source, and to this end we have represented a pulley 24, adapted to be operatively connected to the source of power, such, for example, as an electric motor. By this arrangement the shafts 15 and 16, at opposite ends ofv the furnace, are driven at the same speed, and the furnace hearth 10 is thereby positively driven .by the coperating sprocket wheels at each end of the furnace. he furnace housin is constructed of fire brick in substantialy the usual manner, with a casing of red brick on the outside. The` l brick work of the furnace structure, and" in particular, the arches and skewbacks, are held in position by vertical buckstays 25 and transverse tie-rods 26. The buckstays 25 are preferably pivoted at their lower ends to anchor plates 27, preferably embedded in concrete. Relatively heavy coil springs 28 are associated with the tie-rods 26, for forcing coperating pairs of buckstays on opposite sides of the furnace structure toward one another, thereby maintaining the buckstays firmly pressed against the skewback plates 29.

The skewback plates 29 are L-shaped, as will be seen by reference to Figs. 4 and 6 of the drawings, and are arranged to support the skewbacks 30. The furnace arches are supported by the skewbacks 30 in the usual manner, as will be more particularly pointed out hereinafter. It will be observed by reference to Figs. 4 and 6 of the drawings, that the buckstays 25 contact only with the skewback plates 29, and are thus separated b bflick work structure. By this` arrangement the tie rods 26 and coperating springs 28 serve to force each coperating pair of buckstays firmly against the skewback plates 29, and thus any shrinkage in the brick work structure of the furnace arch, as the furnace dries out, is taken care of and the danger of the arch falling in is practically eliminated. The pivot mounting of the buckstays 25 at their lower ends permits the necessary movement of the buckstays about this pivot to compensate for shrinkage or expansion of the furnace arch.

The interior of the furnace housing is divided into a series of chambers by suspended and worm reduction drives .th

a small space from the side wall of the arches. Thus, an ignition or fuel combustion chamber 3-1 is provided at the charging end of the furnace by the suspended arches 32 and 33. An ore combustion chamber 34 is provided between the suspended arches 35 and 36. he`arches 33 and 35 are suitably spaced in order to accommodate the charging d'evfices for the briqueted working charge, as will be fully described hereinafter. The fume-emitting or oxid-inaking chamber 79 of e suspended arches 36and 37. Three olf-takes 38, 39 and 40 are provided for conductin away from the fume-emitting zone the euent produced therein as the result of the operation. The off-takes 38, 39 and 40 may be connected. to separate fume-collecting devices, or may communicate with a common iiue and fume-collecting device. The ignition chamber 31 has an `off-take 41, and the ore combustion chamber 34 has an oft-ake 42. he gases passing through the offtakes 41 and 42 may be wasted or subjected to any proper treatment.

At the discharge end of the furnace a chamber 43 is provided between the suspended arch 37 and the arch 37. On one tion door 44, while on the other side there is a sliding door 45. These doors are provided as means of easy access to the rear sprockets 14. j Observation doors 46 are provided at appropriate intervals on each side of the fur. ace opening directly into the combustion chambers or zones thereof.

The suspended arches 32, 33, 36 and 37 are held in position in substantially the same manner. Each of these arches is built of a plurality of rectangular fire brick. Rods 47 are embedded in these rectangular fire bricks and passing upwardly through the furnace arch and roof are secured in place by being bolted to transverse beams 48. The sector-shaped spaces between the upper surface of these rectangular fire bricks and the curved lower surface of the furnace arch are filled in with fire brick so as to form the desired partition between the various chambers of the furnace.

The furnace arch or roof 49 is constructed of lire brick in the usual manner and is supported in position by the skewbacks 30, as will be well understood in the art. A cinder fill 50 may be placed on the top of the arch 49. of the furnace, just above the working surface of A hopperV 52 is arranged at the front or charging end of the furnace for feeding briqueted bed fuelon to the traveling grate.

gate or charge leveler 53 is associated with the hopper and is adapted to be raised the furnace is located between p lowering the gate I53, thev depth of charge Aso fed on to the traveling grate 10 may be regulated to the desired amount.

A hopper 55 is arranged to discharge into the space between the suspended arch 33 and the arch 35,. A water-cooled gate or leveler 56 is arranged behind the hopper 55 for leveling the charge fed on to the traveling grate by the hopper. The gate 56, as will be seen by reference to Fig. 7 of the drawings, comprises a hollow shell having transverse baflies 57 for imparting to the cooling medium flowing therethrough a circuitous path.. This cooling medium, such, for example, asgwater, may be supplied to the interior of the hollow shell by an inlet pipe ,58, and withdrawn by an outlet pipe 59.

TheV gate 56 is suspended from 'the top of the furnace structure by vertical rods 60 and may be vertically adjusted with respect to the moving grate by means of the nuts 61.

As hereinbefore explained, the drive forthetraveling grate is connected so that the grate is driven both from the front and rear through the main power shaft. The return grate is supported on riding bars 62 fastened to the side plates 63 of the furnace. The working floor of the furnace is supported on a suitable foundation 64, preferably elevated so as to facilitate the discharge of the exhaust material from the endof the furnace down an inclined chute 65 into cars or the like.

Above the return or lower portion of the travelinggrate 10, and out of contact therewith, is arranged a floor 66, which serves as the bottom wall of the air compartments beneath the upper or working surface of the traveling grate. Fourair boxes 67 extend transversely of the furnace structure, at appropriate intervals between the front and rear thereof, and serve to admit the 'necessary blast of combustion supported gas beneath theaperforated grate .10. The space between adjacent air boxes 67 is divided into two compartments by means of the vertical partitions -68. By this arrangement it will be observed that eight air chambers or compartments are provided beneath the perforated traveling grate 10. Wear plates .67 and,68 are preferably mounted on the tops of the air boxes 67 and partitions 68, respectively, to serve as bearing plates for such portions of the traveling gratev as c ontact therewith. The first air compartment at the front 'or charging end of the'furnace is closed on the outside by a sheet metal wall 69, and a similar wall 70 closes the last air 'compartment at the rear or discharge end of the furnace.

Each of the air boxes 67 extends exteriorly of the furnace at one side,- as will be seen by reference to Figs. 2, 3m and 4 of the drawings. Each air box is connected exteriorly of the furnace by a vertical pipe 71 with the main air conduit 72. Each of the pipes 71 is provided with a slide valve 73 for regulating the air suppl to its air box. Both of the transverse wa ls of each air box 67 are provided with twyers or openings 74. A slide damper 75, terminating ina handle 76 exteriorly of the air box, is .provided for each. series of twyers 74. By moving the handles 76 in or out, the area of the twyers or openingsV 74 can be adjusted, and in this manner the adjustment of the blast secured. It will be observed that while each air box serves to supply thecombustionsupporting gas to two air compartments, the amount of gas supplied to each compartment may be regulated by manipulation of the appropriate slide damper 7 5i.

A trough or pan 77 for .water is preferably arranged in each of the air compartments, and a pipe 78 mayconnect with the troughs for conducting water thereto.

In practising themethod of 'our present invention in the furnace illustrated in the accompanying drawings, the fuel briquets are fed in at the front end of the grate through the hoper 52 and the thickness of the bed fuel is regulated by meansiof the -briqueted working charge is fed on to the ignited fuel briquets through the hopper 55; The depth of the briqueted working charge is regulated by the gate 5-6, which may be set at any desired, height. As previously explained, this gate is cooled by means of circulating water. The briqueted working charge thus spread on the ignited fuel briquets is advanced into what we have called the ore combustion chamber 34, in which the charge is brought up to thereducing temperature. The stack 42 is provided so that, if desirable, the effluent made in this chamber may be recovered separately from that produced in the main oxid-making chamber 79.

The briquetedcharge -now passes under the suspended arch 36 into the main effluent of fume emitting chamber 79, in which the kactive reduction of the charge takes place.

The blow or blast in this chamber is so regulated that complete reduction takes place by the time the charge has traveled to the rear of the chamber. From the exhaust chamber the three olf-takes 38, 39 and 40 conduct the effluent to the flue system and fume collectmaking chamber or zone,

ing devices. as will he well undeistood in the art. Each of the off-takes ft2, 38, 39 and 40, is provided with a slide damper 42', 38', 39 and 10 respectively, for regulating the flow of the effluent so as to help control the temperature at all points of the chamber 79. A trailing door or gate 80 is operatively mounted on the vsuspended arch 37 for preventing the passage underneath the arch and into the chamber 79 of currents or drafts of air.

From the fume emitting chamber 79, the worked-off briquets pass underneath the suspended arch 37 into the rear chamber 45. This chamber is also provided with a stack S2, for balancing the draft between the rear chambers and the fume emitting chamber. As the grate sections pass over the rear sprockets 14, the worked-off charge, consistiyig of a light coal clinker and worked-01T briquets, is discharged on to the chute 65 and thence int-o the receiving hoppers (not shown). A pendant door or gate 8l is pivoted to the arch 37 and serves to maintain the residue discharge opening of the chamber 13 normally closed. When a certain amount of residue banks up against this door 81 it swings open to permit the discharge of the residue down the chute 65.

The traveling furnace hearth moves at a very slow speed, a few feet per hour. The speed of the hearth will be determined by the dimensions ofthe fume-emitting zone, the character and quantity ofmetalliferous material charged and other considerations, which will-be understood by those skilled in the art. In producing zinc oXid in accordance with the invention, we have found a temperature of approximately 1100 to 1250o C. well suited for the fume-emitting or oxidwhen using the well known Franklin furnace zinc oXidores, and at this temperature the briqueted Working charge can ordinarilyy be satisfactorily worked-off or depleted of its zinkiferous content in from two and one-half to three and one-half hours, when operating with a furnace whose oXid-making chamber 79 is about eighteen feet in length and with a grate speed of about seven feet per hour.

In the customary commercial practice of the iVetherill process, the total carbonaceous material in the entire charge, including the bed fuel and the working charge mixture, is

several times greater than the theoretical amount required to reduce the compounds of the volatilizable metals in the charge. It has heretofore been the'general practice to place the greater proportion of the total carbonaceous material of the charge in the working charge mixture. For example, in

the production of zinc oxid, When operating with the well known Franklin furnace zinc oXid ores, itis customary to place from about 15 to 25 per cent. of the total carbonaceous material of the entire charge in the bed fuel, while the remaining 85 to 7 5 per cent. of the total carbonaceous material is mixed with the ore to form the working charge. In general terms, the layer of bed fuel is approximately one inch in depth or thickness, while the working charge mivture is spread over the ignited bed fuel in a layer from about live to seven inches in depth or thickness. v

A very decided improvement in the efficiency of the Wetherill process can be secured by placing the greater proportion of the total fuel of the charge in the form of briquets in the bed fuel, rather than in the working charge as has heretofore been customary. This improvement in the hereto- `ore customary practice of the VVetherill -process is described and claimed in an application for Letters Patent of the United States of Frank G. Breyer, Albert E. Hall and George R. Waltz, Serial No. 310,440, filed July 12, 1919. Vhen a very cons'derable proportion of the carbonaceous or other combustible material of t-he entire charge is thus Withdrawn from the working charge and placed in the bed fuel in the form of briquets, the residual charge consists of a relatively thin clinkered ash, resulting from the combustion of the bed fuel briquets, and the worked-olf metalliferous material. When the 'metalliferous material has been briqueted and spread on the ignited bed fuel briquets, the Worked-off ore briquets are discharged in substantially their original physical form, so that the worked-off briquets may be readily separated from the clinkered ash of the bed fuel briquets.- Furthermore, in view of the fact that the Working charge briquets contain only a relatively small amount of the total carbonaceous material of the charge, the resulting amount of ash in the worked-off metalliferous or ore briquets is relatively small, and such worked-olf briquets may on this account be very advantageously employed in subsequent smelting operations for the recovery therefrom of further metallic values, as will be more fully described hereinafter; Accordingly, in view of the attendant advantages, it is our preferred practice in carrying out the present invention to place the greater part of the total combustible material of the entire charge in the bed fuel briquets, and we have secured excellent results by placing from about 75 to about 85% of the tot-al carbonaceous or'combustible material of the entire charge in the bed fuel briquets.

As a typical instance of the practice of the invention, we will briefly describe, in connection vwith the production of -zinc oxid, a particular operation in which both fuel briquets and a briqueted Working charge were used. l Eight-five (85) per cent. of the total coal of the entire charge was carried in the tion.

inch layer bed fuel briquets, leavingfifteen (15) per cent. of the total coal for mixture with the zinkiferous material in the Working charge. he fuel briquets were made up of Washed coal vwith three (3) per -cent. concentrated waste sulfite. liquor binder. The briqueted working charge consi ted of a mixture of ninety (90) per cent. zinkiferous material and ten (10) per cent, washed dust coal, to which three (3) per cent. waste sulfite liquor vwas added as a binder. `Both the ore and fuel briquets were of the rounded pillow block type.

The levelers or gates 53- and 56 of the accompanying drawings were set to deliver a layer of bed fuel siX inches deep and a three of the briqueted working charge.

In the foregoing operation We secure very satisfactory results by holding the fuel ignition chamber 31 at the minimum temperature for uniform ignitiomthat is, from about 8000 to 9500 C.; the ore ignition chamber 3l at a temperature Where a light zinc flame is visible, for example, from 10000 to 1050O C., and the oXid-making chamber 79, at a uniform temperature of from 11000 to 12500 C., since at this temperature reduction is active, and With the. usual Working mixtures only incipient fusion of the briqueted working charge takes place, so that none of the zinc is trapped into the slag.

T he oxid made in accordance with the foregoingoperation is decidedly superior to that made from charges of the same ore on the customary oXid furnace blocks. Tt is particularly free from any grit or specks and Vvery bright. The recoveries of zinc from the working charge are remarkably high, and we have found by the practice of our invention, that it is possible to secure recoveries better than ninety per cent. as indicated by the clinker analysis.

No bars or rakes need be used, nor need the charge be disturbed in any manner in the method of our present invenonly labor necessary vconsists in feeding the briquets to the furnace and carting away the clinker and Worked-off briquets discharged into the hoppers or cars provided therefor. There is, furthermore, no blowhole trouble, and no sticking of the charge to the side Walls and no loss of blow at the side Walls. The briquets feed uniformly and the ignition of both fuel and Working charge briquets is very uniform. The clinker, consisting of a relatively thin layer of coal ash and burned-out briquets, discharges ,readily and no labor is attendant upon the discharging operation.

Vhen, as in the preferred embodiment of the invention, the metalliferous material of the working harge is supplied to the furnace hearth in the form of briquets, the worked-off ore briquets retain for the most part their original shape with only incipient Some of the working charge briquets will almost inevitably become broken or crushed in the preliminary handling and furnacing operation, but these briquets for the greater part retain their original physical form. After the furnacing operation, these briquets are remarkably hard and almost coke-like inrtheir physical characteristics, and are readily separated from the clinkered coal ashrof the bed fuel briquets. This capability of readily separating the Worked-offA metalliferous or ore briquets from the ash of thei fuel briquets 1s of especial advantage when the Worked-o metalliferous briquets are to be subjected to further treatment for the recovery of valuable metals not volatilizable by the Wetherill process. lVhere the Working charge briquets consist of a mixture of metalliferous material and carbonaceous reducing agent, the Worked-off briquets Will contain, in addition to the Worked-off metalliferous material, the ash Afrom the consumed carbonaceous reducing agent as Well as the unconsumed portion of the reducing agent. The ash is composed principally of silicia and alumina, and is generally objectionable in any subsequent treatment of the Workedoil' metalliferous briquets. Thus for ,example, in those instances in which the Worked-off metalliferous briquets are smelted in a blast furnace for theV production of spiegeleisen a certain amount of fluXing agents is necessary for slagginof off the ash present in the Worked-off metalliferous b-riquets, and when this amount of ash is relatively large an objectionably large amount of iuxing agent is required, With the resultant production of an objectionably large amount of slag. By placing approximately 85% of the total carbonaceous material of the entire charge in the bed fuel briquets, the main bulk, for example, around85 percent.' of the ash of material of the charge is in the clinker resulting from the combustion of the bed fuel briquets, and the Worked-o metalliferous briquets are consequently contaminated With only a relatively small amount of ash. On account of this relatively slight ash contamination of the Worked-olf metalliferous briquets, as Well as on account of their physical properties, these briquets are peculiarly well adapted for subsequent treatment in blast furnaces. In addition to retainingv their original form, these briquets are moreover of a porous character, due to the removal of the volatilizable metals therefrom, and this porous property of the Worked-off briquets is also of advantageV in their subsequent treatment.

While We have hereinbefore specifically described the invention by reference to the production of zinc oxid, including leaded zinc oxid, we Wish it to be understood that the invention is applicable tothe producproduct of improved quality, as well as in tion of other metal compounds of the volaincreased output. Thus by the practice of tilizable metals. In particular, we contemthe invention, We have been able to secure plate the production of basic lead sulfate or recoveries better than ninety 90) per cent. sublimed lead by the method of the invenof the volatilizable metals of the charge, as tion. j In general, the procedure for the proindicated by the clinker anal ses. The furduction of sublimed lead is substantially the nacing operation isk substantially automatic, same as hereinbcfore described, substituting, and requires only casual attention, thereby of course, an appropriate plumbiferous maeffecting a great saving in labor over that terial for the zinkiferous material. Thus, required in the operation of the present day for example, the 'bed fuel is deposited on types of oxid furnaces. The combustion of the traveling hearth of the furnace in the the bed fuel is substantially complete, so manner hereinbefore described andain acthat practically the full caloric value of the cordance with out preferred practice confuel 1s effectively utilized, thereby enabling tains in the form of briquets the bulk or a saving in the amount of fuel required as greater proportion of the total carbonaceous compared with that necessary in working or other combustible material of the entire with the heretofore customary types of oxid charge. The Working charge consists of a furnaces. The worked-off briquets are, in mixture of finely divided galena or native our preferred practice, only slightly conlead suld and carbonaceous material reftaminated with ash and the like, and on this erably briqueted as hereinbefore described. account, as wel] as on account of their he working charge is spread on the ad- `physicalform and properties these Workedperature, the lead sulfd is reduced and (or We clelm :f 90

so-called basic lead sulfate. the Wetherill process which comprises ade effluent containing the sublimed lead vancing through a suitable combustion zone is Withdrawn from the furnace and the a Working charge containinga briqueted briquets COIlalnlIlg aS they d0 a, relatively fuel in the form 0f briquets and 51.111111- small amount of contaminating ash may 'be taneously passing a combustion supporting advantageously subjected t0 any applplllte gas into the charge, and removing the result- 100 Subsequent treatment fOl" th@ TGCOVQIX 0f 'ing effluent; substantially as described. he non-volatilizable metals of the original 2, The process of producing metal oXdS metalliferous material. AS the S0l11C 0f or other compounds of metals volatilized by plumbiferous material, we may use a hlgh the Wetherill process which comprises adgrade of native lead sulfid suitably crushed vancing through a suitable combustion zone and jgged t9 free it from aCCOmPaHJmg a Working charge containing a mixture of ganga@ mate/T1211, 01' We may use lead Sllld briqueted metalliferous material and a re concentrates, such as iotation concentrates, ducjng agent spread on en ignited layer of or other appropriate plumblferuS-Contelnited fuel in the form of briquets and simulng material With PI'0P91'- addtlons 0f $111* taneously passing a combustion supporting 110 rv in the form o f pyrite, alena, brimgas into the charge, and removing the re- SOIIS 01 Other Sultadble S111 TCalylng sulting eiiiuent; substantially as described. agents, Whenever there is a lack of sulfur 3, The procese cf producing metal cXids in the Charge t0 Properly Sulfate the fumeor other compounds of metals volatilized by very accurate and uniform control. of the Wetherill process which comprises adthe tempeatue thloughOut the entll'e lllvancing through a suitable combustion zone nace, and hence during the entire furnacing a WO1-king charge containing briqueted me- OPGMPOn 0f the, Charge, 1S Secured-by the talliferous material spread on an ignited y PmCtlCe ofthe mvefntlon- Thus, the tem* layer of bed fuel `in the form of briquets perature of the variouschambers or zones and simultaneously passing a combustion Of the furnace 021.11 be aeelllately regulated Supporting gas int() the Charge, and removand controlled "by appropriately adjusting ing the resulting effluent; substantially as the slide dampers 7 3 o t e'various air comdescribed,

partments, and the desired operating tem- 4 'I peratures are easily maintained throughout or otherv compounds of metals volatilized the entire furnace. This uniformity of the by the Wetherill process which comprises temperature conditions is attended by pracadvancing through a suitable combustion tically uniform working conditions of the L zone a working charge containing a mixture desired character throughout the furnace, of metalliferous material and a briqueted and results in the production of a uniform reducing agent spread on an ignited layer of bed fuel in the form of briquets and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

5. The process of producing metal oxids or other compounds of metals volatilized by the Tetherill process which comprises advancing through a suitable combustion zone a working charge containing a mixture of metalliferous material and a reducing agent spread on an ignited layer of bed fuel in the form of briquets and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

6. The process of producing metal oxids or other compounds of metals volatilized by the VVetherill process which comprises a vancing through a suitable combustion zone a Working charge. containing material spread on an ignited layer of bed fuel' in the form of briquets` and simultaneously passing a combustion supporting gas into the charge, and removing the resulting efiiuent; substantially as described.

7. The process of producing metal oxids or other compounds of metals volatilized by the VVetherill process Which comprises advancing through asuitable combustion zone a working charge containing a briqueted mixture of metalliferous material and a reducing agent spread on an ignited layer of bed fuel and simultaneously passing a combustioi: supporting gas into the charge, and removing the resulting effluent; substantially as described.

8. rlhe process of producing metal oxids or other compounds of metals` volatilized by the Wetherill process which comprises adlvancing through a suitable vcombustion zone a Working charge containing a mixture of briqueted metalliferous material and areducing agent spread 0n an ignited layer of bed fuel and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

9. The process of producing metal oxids or other compounds of metals volatilized by ythe'Wetherill process which comprises ad- .'ancing through -a suitable combustion zone a Working charge containing briqueted metalliferous material spread on an ignited layer of bed fuel and simultaneously passingv a combustion supporting gas into the charge,

and reu'ioving'the resulting effluent; substantially as described.

10. The process of producing metal oxids or other compounds of metals volatilized'by the WVetherill process which comprises depositing upona, perforated hearth a layer of bed f el inthe form of briquets, igniting spreading thereon a working charge containing a briqueted mixmetalliferous ture of metalliferous material and a reducing agent,'advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passing a combustion supporting gas into the char e, and relnovin the resulting efiiuent; su stantially as escribed.

11. The process of producing metal oxids or other compounds of metals volatilized `by tlieWetherill process which comprises depositing upon a perforated hearth a layer ofbed fuel in the form of briquets, igniting said layer of briquets, spreading thereon a Working charge containing a mixture of briqueted metalliferous material and a reducing agent, advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described'.

l2. The process o'f producing metal oxids or other compounds of metals volatilized by the Wetherill processwvhich -comprises depositing upon a perforated hearth a layer of bed fuel in the form of briquets, igniting said layer of briquets, spreading thereon a Working charge containing briqueted metalliferous material, advancing said hearth and the charge supported thereon through a 95 combustion zone and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; sub-n stantially as described.

13. The process of producing metal oxids 100 or other compounds of metal volatilized by the Wetherill process which comprises depositing upon a perforated hearth a layer o'f bed fuel in the form of briquets, igniting said layer of briquets, spreading thereon a 105 -Working charge containing a mixture of metalliferous material and anbriqueted reducin agent, advancin said hearth and the c arge supported ier'eon through a combustion zone and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

14. rEhe process of producing metal oxids oriother com ounds of metals volatilized by 116 the Wetheril process which comprises depositing upon a perforated hearth a layer of bed fuel in the form of briquets, igniting said layer of briquets, spreading thereon a Working charge containing a mixture o'f 120 metalliferous material'and a reducing agent, advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passing a ,combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

A15. The process of or other compounds o the Wetherill process roducing metal oxids metals volatilized by which comprises depositin upon a perforated hearth "a layer 20.. The process of producing metal oxids of bed el in the form of briquets, igniting or other com ounds of metals volatilized by said layer of briquets, Aspreadlng thereon a working charge containing `metalliferousy material, .advancing said hearth and the charge supported thereon through a combustion zone and simultaneously assing a combustion supportmg. as into t e charge, and removing the resu ting effluent; substantially as described.

16. The process of producing metal oxids or other compounds of metals volatilized by the Wetherill process which com rises depositing upon a perforated heart a layer of bed fuel, ignitmg said layer of bed fuel, spreading thereon a workin charge containing a briqueted mixture o metalliferous material' and a reducing agent,.advanc1ng said hearth and the charge supported thereon through a combustion zone and simultaneously passing a combustion supportlng gasl into the char e, and removing the resultin eiuent; su stantially as described.

17. he process of producing metal oxids or other compounds of metals volatilized by the Wetherill process which comprises depositing upon a perforated hearth a layer of bed fuel, igniting said layer of bed fuel, spreading thereon a Working charge containing a mixture of briqueted metalhferous material and a reducing agent, advanclng Asaid hearth and the charge supported thereon through a combustionzone and simultaneously passing a combustion supporting gas into the charge, and removing the result` ing eiuent; substantially as described.

18. The process of producing metal oxids orY other compounds of met-als .volatilized by.

the Wetherill process which comprises depositing upon a perforated hearth a layer of bed fuel, igniting said layer of bed fuel, spreading thereon a working charge containing briqueted metalliferous material, advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

19. The or other compounds of metals volatilized by the Wetherill process which comprises dcpositing upon a furnace hearth a layer of bed fuel containing the greater part of the total combustible material of the entire charge in the form of briquets, layer of bed fuel briquets, spreading thereon a Working charge containing a briqueted mixture of metalliferous material and a reducing agent, advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

process of producing metal oxidsigniting said I alliferous material process which comprises de- 'charge in the form of briquets, igniting said layer'of 'bed fuel briquets, spreading thereon a working charge containi a mixture of b riqueted metalliferous material and a reduclng agent, advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passing a combustlon supporting gas into the charge, and removing the resulting feflluent; substantially as described.

21. The process of producing metal oxids or other com ounds of metals volatilized by theWetheril process which comprises depositing upon a furnace hearth a layer of bed fuel containing the greater part of the total combustible material of the entire charge in the form of briquets, igniting'said layer of bed fuel briquets, spreading thereon a Working charge containing briqueted metalliferous material, advancing said hearth and the charge supported thereon throu h a combustion zone and simultaneous y passing a combustion supporting gas into the charge, and removing the re- Sulting efliuent; substantially as described.

22. The process of producing metal oxids or other compounds of metals volatilized by the Wetherill process which comprises depositing upon a furnace hearth a layer of bed fuel containing the greater part of the total combustible charge in the form of briquets, igniting said layer of bed fuel briquets, spreading thereon a Working charge containing a mixture of metalliferous material and a briqueted reducing agent, advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent, substantially as described.

23. The process of producing metal oxids or other compounds of metals volatilized by the Wetherill process which comprises depositing upon a furnace hearth a layer of bed fuel containing the greater part of the total combustible material of the entire charge in the form of briquets, igniting said layer of bed fuel briquets, spreading therein a Working charge mixture containing metand a reducing agent, advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passing a combustion supporting gas into the charge, and removing the resulting efluent; substantially as described.

24. The p-rocess of roducing metal oxids or other compounds of) metals volatilized by a furnace hearth a layer of material of the entire *the Wetherill process which comprises depositing upon a furnace hearth a layer of bed fuel containing the greater part of the total combustible material of the entire charge in the form of briquets, igniting said layer of bed fuel briquets, spreading thereon a Working charge containing metalliferous material, advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

25. The method of producing sublimed lead by the Wetherill process which comprises advancing through a suitable comustion zone a Working charge containing a briqueted mixture of plumbiferous material and a reducing agent spread on an ignited layer of bed fuel in the form of briquets and simultaneously passing a coinb-ustion supporting gas into the charge, and removing, the resulting effluent; substantially as described.

26. The method of producing sublimed lead by the Wetherill process which comprises advancing through a suitable combustion Zone a Working charge containing a mixture of briqueted plumbiferous material and a reducing agent spread on an ignited layer of bed fuel in the form of briquets and simultaneously passing a combustion supporting gas into thecharge, and removing the resulting effluent; substantially as described.

27. rlhe method of producing sublimed lead by the `Wetherill process which comprises advancing through a suitable combustion zone a Working charge containing briqueted plumbiferous material spread on an ignited layer of bed fuel in the form of briquets and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

28. The method of producing sublimed lead by the Wetherill process which comprises advancing through a suitable combustion zone a Working charge containinga mixture of plumbiferous material and a briqueted reducing agent spread on an ignited layer of bed fuel in the form of briquets and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

29. The method of producing sublimed lead by the Wetherill process which comprises' advancing through a suitable combustion zone a Working charge containing a mixture. of plumbiferous material and a reducing agentspread on an ignited layer of bed fue] in the form of briquets and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

30. The method .of producing sublinied lead by the VVetherill process which comprises advancing through a suitable combustion zone a Working charge containing lumbiferous material spread on an ignited ayer of bed fuel in the form o'f briquets and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

31. The method of producing sublimed lead by the Wetherill process which comprises advancing thrugh a suitable combustion zone a Working charge containing a briqueted mixture of plumbiferous material and a reducing agent spreadon an ignited layer of bed fuel and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

32. The method of producing sublimed lead by the Wetherill process which comprises advancing through a suitable combustion zone a Working charge containing a mixture of briqueted plumbiferous material and a reducing agent spread on an ignited layer of bed .fuel and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

33. rlChe method of producing sublimed lead by the llVetherill process which comprises advancing through a suitable combustion zone a Working lcharge containing briqueted plumbiferous material spread on an ignited layer of bed fuel and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

34:. rlhe method ofi producing sublimed lead by the Wetherill process which comprises depositing upon 'a perforated hearth a layer of bed-fuel in the form of briquets, i gniting said layer of briquets, spreading thereon a Working charge containing a briqueted mixture of plumbiferous material and a reducing agent, advancing said hearth and the charge supported thereon through a combustionY zone and simultaneously passing a combustion su-pporting gas into the charge, and removing the resulting effluent; substantially as described. i

35. The method of producing sublimed lead by the `Wetherill process which comprises depositing upon a perforated hearth a layer of bed fuel in the form of briquets, igniting said layer of briquets, spreading thereon a Working charge containing a mix'- ture of briqueted plumbiferous material and va reducing agent, advancing said hearth and the charge supported thereon through a combustion Zone' and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

37. rl`he method of producing sublimed,

lead by the VVetherill process which comprises depositing upon'a perforated hearth a layer of bed fuel in the form of briquets, igniting said layer of briquets, spreading thereon a Working charge containing a miX- ture of plumbiferous material and a briqueted reducing agent, advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passing a combustion supporting gas into the charge, and ren'loving the resulting eluent; substantially as described.

38. The method of producing sublimed lead by the lVetherill process which comprises depositing upon a perforated hearth a layer of bed fuel in the form of briquets, igniting said layer of briquets, spreading thereon a. Working charge containing a mixture of plumbiferous material and a reducing agent, advancing said hearth and the charge supported thereon through a combustion zone and sinmltaneouslv passing a combustion supporting gas into the charge, and removing the resultinig effluent; substani tially as described.

39. The method of producing sublimed lead by the Vetherill process which comprises depositing upon a perforated hearth a layer of bed fuel in the form of briquets, igniting said layer of briquets, spreading thereon a Workin charge containing plumbiferous materialq, advancing said hearth and the-charge supported thereon through a combustion zone and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

40. The method of producing sublimed lead by the Wetherill process which comprises depositing upon a perforated hearth a layer of bed fuel, igniting sait layer of bed fuel, spreading thereon a Working charge containing a briqueted mixture of plumbiferous material and a reducing agent, advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passing a'combustion supporting gas into the charge, and removing the resulting eiiluent; substantially as described.

41. The method 0f producing sublined lead by the Wetherill process which coming a combustion `on through a combustion zone upon a perforated hearth charge containing briqueted plumbiferous material, advancing said hearth and the charge supported thereon through a com- -bustion zone and simultaneously passing a combustion supporting as into the charge, and removing the resu` ting effluent; substantially as described. y

43. The method of producing sublimed lead by the Wetherill process Which comprises depositing upon a furnace hearth a layer of bed fuel containing the greater part of the total combustible material of the entire charge in the form of briquets, igniting said layer of bed fuel briquets, spreading thereon a Working charge containing a miX- ture of briqueted plumbiferous material and a reducing agent, advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passsupporting gas into the charge, and removing the resulting eiuent; substantially as described.

44. The method of producing sublimed lead by the Wetherill process Which comprises depositing upon a furnace hearth a layer of bed fuel containing the greater part of the total combustible material of the entire charge in the form of briquets, igniting said layer of bed fuel briquets, spreading thereon a Working charge containing a mixture of lbriqueted plumbiferous material and a reducing agent, advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passmg a combustion supporting gas into the charge, and removing the resulting eflluent; substantially as'describe 45. The method of producing sublimed lead by the Wetherill process which lcomprises depositing upon a furnace hearth a layer of bed fuel containing the greater part of the total combustible material of the entire charge in the form of briquets, igniting said layer of bed fuel briquets, spreading thereon a Working charge containing briqueted plumbiferous material, advancin said hearth and the charge supported thereand simultaneously' passing a combustion supporting gas in to the charge, and removing the resulting effluent; substantially as described. 46. The method of producing sublimed lead by the Wetherill process which comprises depositing upon a furnace hearth a layer of bed fuel containing the greater part of the total combustible material of the entire charge in the form of briquets, igniting said layer of lbed fuel briquets, spreading thereon a working charge containing a mixture of plumbiferous material and a briqueted reducing agent, advancing said hearth and the charge supported -thereon through a combustion zone and simultaneously passing a combustion supporting gas into the charge, and removing the resulting el'liuent; substantially as described.

i7. The method of producing sublimed lead` by the Vetherill process which comprises depositing upon a furnace hearth a layer of bed fuel containing the greater part of the total combustible material of the entire charge in the form of briquets, igniting said layer of bed fuel briquets,'spreading thereon a working charge mixture containing plumbiferous material and a reducing agent, advancing said hearth .and the charge supported thereon through a combustion zone and simultaneously passing a combustion supporting gas into the charge, and removing the resulting effluent; substantially as described.

48. The method of producing sublimed lead by the Wetherill process which com' prises depositing upon afurnace hearth a layer of bed fuel contalning the greater part of the total combustible material of the entire charge in the form of briquets, igniting said layer of bed fuel briquets, spreading thereon a working charge containing plumbiferous material, advancing said hearth and the charge supported thereon through a combustion zone and simultaneously passing a combustion supporting gas into the charge, and4 removing the resulting eiluent; substantially as described.

a9. A metallurgical furnace for producing metal oxids or other compounds of metals volatilized by the Wetherill process comprising a combustion chamber, a traveling perforated hearth operatively arranged' to support and advance through said chamber a charge containing briqueted material,

said briqueted materlal contacting with the' side walls of said chamber and thereby preventing any loss of blow between the advancing charge and the side walls of the chamber; means for depositing a'layer of bed fuel on the traveling hearth, means whereby said layer of bed fuel is ignited,

means for spreading a working charge on` the ignited layer of bed fuel, means forremoving the effluent from said combustion chamber, and means for passing a .combustion supporting gas through the perforations of said hearth and into the charge supported thereon.

50. A metallurgical furnace for producing metal oxids or other compounds of metals volatilized by the Wetherill process comprising a combustion chamber, a continuous traveling perforated hearth operatively arranged to support and advance through said chamber a working charge, means for depositing a layer of bed fuel in the form of briquets on the traveling hearth, means whereby said layer of briquets is ignited, means for spreading a working charge containing briqueted material on the ignited layer of bed fuel, the aforesaid briquets of the charge contacting with the side walls of said chamber and thereby preventing any loss of blow between the advancing charge and the side means for removing the eiiluent from said chamber, and means for passing a combustion supporting gas through the perforations of said hearth and into the charge supported thereon.

511. A metallurgical apparatus comprising a combustion chamber, a traveling perforated hearth operatively arranged vto support and advance through said chamber a working charge, means for supplying a charge containing briqueted material to said traveling hearth whereby said briqueted material forms an operative seal between the stationary 'side walls of said chamber and the kadvancing charge, and means for passing a combustion supporting gas through the perforations of said hearth and into the charge supported thereon.

52. 'In a process for volatilizing and oxidizing metal values involving the blowing of air into a continuouslyadvancing bed containing the metal bearing material and combustible material under conditions which will leave the worked-olf chargeas a clinker, and which will produce a volatile fume, the step of supplying at least part of the charge in the form of briquets; substantially as described,

53. In a rocess for producing sublimed lead involving the blowing of air into a continuously advancing bed containing the metal-bearing material and combustible niateral under conditions'which will leave the worked-ofil charge asa clinker and which will produce a volatile fume, the step of `supplying at least part of the charge in the form of briquets; substantially as described.

In testimony whereof we afliX our signatures.

JAMES A. SINGMASTER. FRANK G. BREYER. EARL H. BUNCE.

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