US1815260A - Method of producing zinc - Google Patents

Description

July 21, 1931. F. R. KEMMER 5, 6

METHOD OF PRODUCING ZINC Filed June 12, 1929 2 Sheets-Sheet 1 COOLER- COOLER INVENTOR Frank R. Kemmer ATTORN EY July 21, 1931. F. R.-KEMMER METHOD OF PRODUCING ZINC Filed June 12, 2 sheets-sheet 2 KMAOOU F KMJOOU INVENTOR Frank R. Kemrner A OR EY Eatented July 21, 1931 NTED STATES PATENT OFFICE FRANK R. KEMMER, OF.LA.RCHMONT, NEW YORK, ASSIGNOR TO AMERICAN CYANAMID COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE METHOD or PRODUCING ZINC Application filed June 12,

The present invention relates to the protection of apparatus and of materials therein under certain conditions, and more particularly to a method of supplementing or temporarily replacing gas flowing through an apparatus by an inert atmosphere either to assist in maintaining a desired pressure within the apparatus, or to prevent the admixture with the gases therein of other fluid substances which might form. explosive mixtures therewith or which might have a deleterious effect on the process or product.

One specific embodiment of the invention concerns the zinc electroth'ermic smelting industry wherein it is common practice to provide a furnace for the zinc ore or material to be treated, to which is coupled a condenser or series of condensers for receiving vaporized material from the furnace for condensation to metallic zinc.

Where zinc ores are smelted a considerable quantity of carbon monoxide is given off together with zinc vapors, and where a furnace is being initially started and, consequently, the atmosphere thereof and of the condenser contains air, this-carbon monoxide mixes therewith and there is danger of an explosion upon a rise in temperature, the striking of a spark, or the presence of a flame, due to the mixture of oxygen and carbon monoxide. I

The same danger exists in a furnace which is being closed down or has been temporarily closed down, as due to the fact that the entire outfit cools upon ceasing operation, the furnace and condenser have a tendency to draw in air througheither the cracks in the furnace and condenser or through the ordinary outlet means. As a result there is present the liability of an explosion from an admixture of oxygen and carbon monoxide while the furnace is'still hot or as soon as the furnace is again started.

It is, therefore,among the objects of this invention to prevent the possibility of an explosion'in either the furnace or the condenser or both by supplementing the flow of gases therethrough, or displacing the air. therein by a gas or mixture of gases which 1929. Serial No. 370,221.

the presence of water or steam therein or the decomposition of the same.

As'diagrammatically showing the application of the invention to a zinc condenser, reference is had to the accompanying drawings, in which Fig. 1 is a side view, partly in section of an assembly embodying the invention, and

Fig. 2 is a plan View of the assembly of Fig. 1.

In practicing the invention I find it convenient to utilize the gaseous products of combustion from an oil burner 1 or the like. Obviously, the invention isnot to be limited to this particular method of forming the displacing gases but such an apparatus has been found to be eflicient and satisfactory. These gaseous products of combustion are preferably passed through cooling devices 2 and 3, and a water precipitator 4 of any desired construction so that all excess moisture is condensed and drained from the system before the gas is delivered to the condenser and furnace combination. The resulting products of combustion contain principally nitrogen, carbon dioxide, carbon monoxide and water vapor and if the air supply is properly proportioned the products of combustion can-be controlled to contain for all practical purposes only nitrogen and carbon dioxide, after the condensation of the water vapor, and I can readily obtain a as which analyses from 98.4% to 99.3% C8 and N In practice I find it desirable to introduce these gases through a pipe 5 at thebottom of the condenser to a manifold 6, having inlets 7 entering the condensers 8 at a plurality of'points, so that the atmosphere therein is displaced in an upward direction lie \ ture with carbon monoxide are contemplated by this invention, and instead of the products of combustion mentioned, which consist substantially of carbondioxide, and nitrogen, one may use carbon dioxide alone from any desired source, or nitrogen, or, as a matter of fact, any gas substantially free from ,uncombined oxygen, or any inert gas.

A suitably valved oiftake 9 may be provided in the pipe 5, for sampling the gases to determine their constituents before admitting them to the condenser 8. Valve 10 can be used to purge the gas generating system of any air or any detrimental mixture, before allowing gas to flow into the condenser system.

. Anysystem containing carbon monoxide or other gas or gases of an explosive nature is, of course, subject to explosion hazard if the system is not entirely free of leaks and kept under pressure sufficient to prevent en trance of air.

In the electrothermic smelting of zinc ores condensers of large capacity are used and it is of the greatest importance that these operations be conducted without interruption from explosions. In this case chance for the formation of an explosive mixture of gas and air is greatest during the periods when a new system or an old one to be restarted, is placed in operation and at the close of an operating campaign when the apparatus ceases to be used and must be dis- 1 exit-stack is opened to permit a steady flow charged of its residual gases.

In starting a new furnace the system contains only air. As soon as the smelting unit (not shown) is placed in operation it generates gases containing a mixture of carbon monoxide and carbon dioxide, the proportion of carbon monoxide increasing with the temperature. These gases enter the condenser 8 containing only air and very readily form an explosive mixture therewith and the present invention is designed to flush out such air and simultaneously replace it with inert gas so that the gases coming over into the condenser from the furnace cannot form an explosive mixture. When the condenser has become filled with inert gases as indicated by the issuance thereof through valves 11, in the condenser roof, the furnace gases are then permitted to enter the condenser, the condenser roof openingsare closedand when the pressure within the system has reached the proper point a damper (not shown) in of gases into the exit piping system. When the gases are thus escaping from the system 7 system functions normally under a flow of furnace gasesonly. Y

the flushing gas supply is cut off and the In closing down a system I have the reverse condition where the condenser, in-, I

stead of being flushed of its air content er if it" appears desirable to do so. however, is usually unnecessary once the condenser proper has been completely filled with inert gas and the roof valves have been opened, because any entrance of air from the outside cannot form an explosive mixture therewith. It is, of course, preferable from the standpoint of absolute safety to keep the system under a slight pressure from the inert gas generator until no more carbon monoxide or other gases can find its way into the condenser from the furnace.

While I am aware that it is old to conduct various operations in the presence of an inert gas to prevent explosions, yet it is to be understood that I am not claiming such a method broadly but as far as I am aware I am the first to have proposed a method of operating a system wherein the' atmosphere therein is supplemented or replaced by an inert one either to maintain a desired pressure or to prevent leakage of fluid into theapparatus, or to operate a zinc furnace or condenser, or both, displacing the atmosphere therein with a gas which does not form an explosive mixture with carbon monoxide, as set forth in the appended claims.

What I claim is:

1. A method of operating a condenser which includes the steps of forming gaseous combustion products, removing excess water therefrom, and displacing the atmosphere in the condenser by means of said gaseous .products.

I 2. A method of operating a condenser which includes the step of removing excess water from a gas which does not form an explosive mixture. with carbon monoxide, and

then displacing the. atmosphere in the condenser with said gas.

3. A method of operating a condenser which includes ous combustion products, collecting the same, removing excess moisture therefrom,

and displacing the atmosphere in the condenser by means of said aseous products.

In testimony whereof I have herelinto subscribed my name this 27th day of May,

FRANK R. KEMMER.

the steps of forming gase-.

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