US1244504A - Continuous zinc-smelter. - Google Patents

Description

W. McA. JOHNSON.

CONTINUOUS ZlNC SMELTER.

APPLICATION FILED FEB. 4, 19m.

Patented Oct. 30, 1917.

WITNESSES.

w 2 h Agg/vroz? f ATTORNEYS WOOLSEY MGA. JQHNSQN, 0E HARTFORD, CONNECTICUT.

CQNTIIIUQUS ZINC SMELTER.

Specification of Letters Patent.

Patented Oct. 30, 1%1'3'.

Application filed February 4, 1915. Serial 1i 0. 6,053.

To all whom it may concern Be it known that I, WOOLSEY Moll. donnsou, a citizen of the United States, and residing at Hartford, in the county of Hartford and State of Connecticut, have invented a new and Improved Continuous Zinc-Smelter, of which the following specification is a full disclosure.

. This invention deals with an apparatus for economically deriving volatile metals, such as zinc, from ore or other material containing that metal, and for doing so by a continuous smelting operation and in such a manner that the metal will be rendered directly available in a commercially desirable state.

Zinkiferous ores have heretofore been smelted, by successive and quite distinct operations, in such a way as to necessitate frequent handling or manipulation of the material in subjecting it to the successive steps, and the instrumentalities aiding in the general smelting scheme have heretofore been more or less segregated. All this has contributed to the high cost of the ultimately obtained metal.

Now, this invention seeks to render available a unitary or self-contained smelting plant or structure so designed that properly conditioned ore may be continuously delivered into the receiving end of the struc ture, and be continuously treated therein to the end that zinc will be continually evolved and condensed directly into commercially available spelter at the delivery portion of the apparatus.

Another object is to formulate a system that will enable zinkiferous ores, containing large amounts of iron and sulfur, together with small amounts of copper and other valuable metals, to be smelted continuously and economically.

- This invention may be analyzed as com prising a continuous container in the nature of a more or less complex and extensive retort simultaneously subjected at its remote ends to widely different temperature conditions, 2'. e., by being externally but moderately heated by ordinary fuel near its charge-receiving end or non-fusing zone and by being internally but intensely heated by electricity near its metal-yielding end or in its charge-fusing zone; said retort being organized to provide for a steady progression of a fusible charge therethrough, whereby it may be successively subjected to widely difi'erent temperature conditions; first, to efi'ectuate certain preparatory endothermic reactions and, second, to bring the charge ultimately to a state of fusion to carry out the ultimate smelting reactions. One of the dominant structural characteristics of this invention is that the container near its charge-receiving end is formed of zone is, on the other hand, confined by rel-' atively thick heat-insulating walls.

Continuing now by way of a more detailed description of one of the various possible embodiments of this invention, 1 indicates a preheating apparatus which preferably occupies an elevated position, which conveniently may be located immediately above the smelting furnace proper 2. This relation may best be realized by providing a floor or elevated platform 3 which is held up by means of the pillars 4, constructed of channel iron or otherwise. The preheating dome 1 will be constructed of fire-brick, or other suitable heat-resisting material, and internally it will contain or be constructed to provide a series of preheating floors 5, 6, 7 and 8. These floors are intended to receive a layer of the suitably prepared charge and they are so arranged that the charge can be raked or rabbled or otherwise continuously fed from the uppermost to the lowermost levels in succession to expose fresh por= tions of the charge to the preheating con ditions. Conveniently, this may be accom plished by providing each floor with a discharge port as indicated by 9, 10, 11 and 12 arranged in ofiset relation so that when the charge is rabbled oii of the floor 5 into the opening 9 it will fall onto the floor 6, and so on in succession from one to the other. To prevent furnace gases and air from oxidizing the charge while it is bein heated a series of roofs 13, 14, 15 and 16, c osed off by side walls 17, 18, 19, 20 and 21, may be provided, thereby forming a closed continuous conduit for the charge. The charge is suitably caused to progress, as before stated, and to enable this to be done a series of rabble doors 22,23, 24' and 25 open through the external walls of the preheating dome and by means of suitable passageways permit access to the various floors to enable the rabbling to take place.

The above structure is intended to be used as a means instrumental in carrying out an important metallurgical change in the zinkiferous material. That is to say, I intend, as a preliminary to the actual smelting operation to efiect a metallurgical change in the condition of the ore, rendering it more suitable for economic smelting. The zincbearing charge, for example, after having its sulfur content reduced to a point materially less than will ordinarily exist in the native ore, and materially greater than is customary after the roasting operation of retort smelting, is mixed with a suitable amount of carbon, preferably capable of evolving enough gas to cause a draft in the preheating, and is then caused to pass through the preheating dome 1 by being admitted through the port 26, whereby it will be exposed to a temperature of about 1050 degrees. This temperature will suffice, during the time interval consumed by the passage of the ore, to reduce certain products in the charge and materially change its metallurgical condition as by forming a highly reactive sponge iron and yet without evolving substantial quantities of zinc vapors. During this passage, substantially all of the cadmium will be reduced and evolved as a vapor and carried to the point of collection by the hydro-carbon gases given off by the charge.

The composition of the charge and the metallurgical steps and reactions involved are fully disclosed in my copending application, Serial No. 854,169, filed July th,

1914, and reference thereto is herein made as a part of this application and to avoid the necessity of repetition.

It is noteworthy that the heat utilized for the foregoing step is derived directly from the combustion of fuel, as distinguished from the transformation of electricity, and this has many advantages. To that end, a combustion chamber A is formed by the walls D of suitable heat-insulating material and through a suitable door C the fuel is fed onto the grate B. The products of combustion pass up a chimney formed of the heat-insulating walls F and preferably through a suitable checker-work E which acts as a thermal balancewheel and maintains an even temperature, even though the firing on the grate B should be irregular.

These products of combustion are in a very highly heated condition, though not sufficiently so as to cause the ore mixture in the preheater tobe completely smelted, although such mixture may be partially smelted so as to practically eliminate certain valuable elements before the mixture reaches the secondary or more int nsive smelting operation, which, in this embodiment, is carried out in an electric furnace wherein zinc is smelted. The flame and waste gases now follow the course indicated by the arrows a.bcdefgh and 2' and thus pass from the flue G to the chimney H so as to circulate around the retorts and transmit the heat through the thin heat-conducting walls thereof and thereby preheat the charge in said retorts. It is noteworthy that the current of waste heatyielding gases travels conversely to the current of heat-absorbing mixture, thereby making for efliciency.

The preheated mixture now passes to the intensive smelting zone in which are recovered certain more refractory elements, such as zinc, magnesium, iron, etc. An electric furnace is shown for carrying out this step. An important characteristic of this invention lies in the unitary construction of the apparatus whereby the preheating and intensive smelting zones are formed in one unitary structure. This makes for a practically continuous and uninterrupted treatment of the material to be smelted.

When the material reaches the last stages of the preheating operation, it enters the chute 30 which leads downwardly into the electric furnace 31 formed of the bottom 32, the side walls 33 and the dome 34. One or more doors or dampers 35 control the rate of passage into the intensive smelting zone, wherein the material is reduced to yield a lowermost lath or layer of the heavier metals or products which may be periodically tapped through the tap-hole 36. Less heavy reduction products, such as copper or iron sulfids (so-called matte), will float upon the lowermost bath and may, in turn, be withdrawn through the tap-hole 37; and in like manner the uppermost bath of slag will be tapped out through the slag-monkey 38. This bath of slag is maintained at the smelting temperature by means of an electric current conducted by the electrodes 39 and 40 which are fed into the electric furnace as fast as needed by suitable feeding means.

The zinc reduced by the solid carbon in the electric furnace is volatilized and passes through the outlet vent 40 into the chamber 41 of the conduit 42 connecting the electric furnace with the chamber 43 of the condenser 44, wherein the zinc vapor is condensed and withdrawn through the part 45. Excess vapor-pressure is relieved by means of the prolong 46. The condenser is maintained at the proper temperature by means of hot gases generated in the combustion chamber 47 by fuel burning on the grate 48. These gases take the course indicated by 7c-Lm n/0-p'r-s and t and maintain the condensing chamber at the temperature best adapted to yield cohesive metal.

instance Having thus revealed this invention 1 claim as new and desire to secure the following combinations of steps and elements, or equivalents thereof, by Letters Patent of the United States l. A unitary smelting apparatus combining an electric furnace having heat-insulating Walls; a preheating retort having heatconducting thin Walls and connected with said furnace whereby snieltable material may be preheated in said retort and passed directly into said furnace Without being exposed to air; and a fuel-burning furnace ar ranged to heat said retort; and a condenser adapted to receive all the gaseous prcducts from said furnace.

2 A unitary smelting apparatus comloining'an internally heated electric furnace; a preheating retort adapted to retain a granulated smeltalole material; a fuel-burning furnace for externally firing said retort; a drop-chute hermetically connecting said re tort and electric furnace, whereby preheated material may gravitate through said chute into said furnace; and a condenser arranged to receive all gases from said electric furnace independently of said fuel-burning furnacea 3. A unitary smelting apparatus cornhining an internally heated electric furnace; a series of retort-sections arranged zig-zag and hermetically connected with said electric furnace; and a fuel bug furnace for externally firing said retort-sections.

4:. A combined electric and fuel smelting apparatus comprising an electric furnace; a condenser connected therewith to receive all gases therefrom; a preheating retcrt independent of said condenser adapted to de= liver preheated material into said furnace; and an independent furnace for heating said preheater. 5, A smelting apparatus combining an electric furnace; a preheater superimpose thereover; means for rabloling material in said preheater; an independent furnace for heating said preheater; and a condenser for receiving all gases evolved in said electricfurnace In Witness whereof, I hereunto suhscrihe my name, as attested by the two subscribing Witnesses.

WQQLSEY McA. JQHNSUNQ Witnesses:

l/L Q11 Ccornn, Gconn,

All

Images