US2007027A - Apparatus and process for the manufacture of zinc dust - Google Patents

Description

July 2, 1935. 'F w, SCHULZE 2,007,027

APPARATUS AND PROCESS FOR THE MANUFACTURE OF ZINC DUST Filed May 51, 1954 INVENTOR.

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Patented July 2, 193E;v

UNITED STATES .PATENTAI OFFICE" i This invention relates to a process and apparatus for the manufacture of zincjdust, and is particularly directed to processes and apparatus wherein two retorts and two condensers are interconnected whereby on the cessation of operation .of one retort the temperature of the gases in its condenser is maintained and the contraction of the gases in the condenser prevented. In'the manufacture of zinc dust it iscustomary to charge zinc, 'or'zinc containing material, into a retort wherein the zinc is vaporized. The zinc vapors are then led into a condenser where they are cooled to form zinc dust.

The temperature of gases in the condenser is, naturally, rather high and when the charge of zinc is exhausted and the zinc vapors are no longer discharged into the condenser the temperature of the gases in the condenser drops. As soon as the charge of zinc is exhausted it is necessary to supply more zinc to the retort, and to do this the retort is opened. As the gases in the condenser .cool they naturally diminish in volume with the result that, while the retort is open, air is sucked into the condenser to make up for the decrease in volume of the gases in the condenser. When the retort is again started up the first zinc vapors led into the condenser react with the" air therein to form zinc oxide, and the zinc ,dust contains an undesirable amount of zinc oxide.

It has been proposed to provide an expansible breather into which the gases could expand while hot, and, on the cooling of the gases, the expansible breather would diminish in size with-- the contraction of the gases. This, however, requires the installation of extra apparatus with a corresponding increase in'costs.

It is an object of my invention to prevent the drawing of 'air into a condenser while its retort is not operating without the use of extra apparatus and at a negligible cost. It is a further object 01' my invention to provide a process and apparatus with which zinc dust very low in zinc oxide can be made. A still further object of my invention is to provide a means of using existing zinc dust. manufacturing equipment with a minimum amount of modification. Further objects will appear as the description of my invention proceeds.

My invention contemplates interconnecting'adjacent condensers witha suitable pipe. This is easily done, for in most cases the retort-condenser units are set in pairs so that one worker can care for two such units. Suitable valves are provided so that if one retort is to be subjected to lengthy repairs it can be isolated from the other retortcondenser unit. Obviously more than two retortcondenser units can be similarly interconnected ii desired. 4

In the accompanying drawing there is shown illustrative apparatus for the practice of my inv vention: V

Figure 1 shows a pair of retort-condenser units modified according'to'the preferred manner of my invention Figure 2 shows a slightly modified form of-my invention. g

In Figure 1 there are shown condensers l and 2 each communicating with retorts 3, 3. At the lower end of each condenser there is provided a suitable valve 6 and zinc dust receptacle l. The specific construction of the retorts, retort heating 13 means, condensers, etc., forms no. esential part of my invention, and may be oi-anydesired type.

The units'illustrated in the drawing are of the type shown and claimed in-U. S. Patent 1,762,716, to H. A. Grine.

According to my invention a pipe 8 extends from the top of condenser l to the top of condenser 2. A suitable valve 1 is interposed in pipel. f In the operation of theembodiment-"of Figure 25 1, both retorts are set in operation in the usual way. Now, assuming that the retort of condenser vl needs recharging, the valve 1 is opened "and the retbrtopened and charged as quickly as possible. During the charging of the retort zinc 30 vapor, hot zinc dust, and a slight amount of hot gases pass from condenser 2 into condenser I and maintain the gases therein at practically operating temperature. No undue amount of air, therefore, is drawn into condenser i and, as soon 35 as the retort is charged and started operating, the zinc dust formed in condenser. l is substantiallyfree of zinc oxide. A, similar procedure is followed when the retort of condenser 2 needs recharging. p

The valve 1 is open during recharging and it maybe closed, if desired, between such recharging periods. It is not necessary, of course, to close it during normal operation. If one of the retorts or condensers needs repairs, .or is for any 45 other reason to be out of use for a considerable period, the valve I may be closed and the other" retort-condenser unit operated alone.

In the modification of Figure 2 there'is seen an apparatus like that of Figure 1, except that 50 valves 8 and I 0 are provided between the re-x torts oi condenser I and 2 respectively. When a; retort is being recharged the valve between it and its-condenser may be closed to more efiectively prevent access of air to its condenser. The

gases in the condenser are maintained at substantially the operating temperature by the pipe 8. If the pipe 8 were not provided, the cooling of the gases in the condenser would cause the infiltration of air, or failing that, the collapse of the condenser. The valve 1 is used as in the embodiment of Figure 1, but it may be omitted if desired. I do not prefer the modification of Figure 2, as it is very desirable to have the line he tween the retort and condenser as short as possible and the insertion of a valve necessarily lengthens it. Also, the valves and M are subject to very high temperatures, while valve I is subjected to much lower temperatures.

While I have shown specific forms of apparatus above, I do not intend to be limited thereby, the scope of my invention being set forth in the appended claims.

I claim:

1. In a process for the manufacture of zinc dust, the step comprising maintaining the gases in a condenser near normal operating temperatures while a retort which communicates with the condenser is not operating.

2. In a process for the manufacture of zinc dust in an apparatus comprising a retort and communicating condenser, the step comprising supplying hot inert gases, zinc vapor, and hot zinc dust to the condenser while the retort is not in operation whereby the gases inthe condenser are maintained near normal operating temperatures.

3. In a processior the manufacture of zinc dust in an apparatus comprising two retortcondenser units, the steps comprising leading hot zinc dust and zinc vapors from one condenser to a second condenser when the retort which normally discharges zinc vapor into said second condenser is not in operation.

4. An apparatus for the manufacture of zinc dust comprising two retort-condenser units and means for permitting the passage of zinc vapors from one condenser to the other.

5. An apparatus for the manufacture of zinc dust comprising a retort, a condenser communicating therewith, a second retort and condenser, a passage from one condenser to the other providing communication between the retorts, and

valve means for interrupting the communication between the retorts.

6. An apparatus for the manufacture of zinc dust comprising a retort, a condenser communicating therewith, a second retort with a second condenser communicating therewith, a pipe connected to each of the said condensers providing communication therebetween, and valve means in the pipe,

7. An apparatus for the manufacture of zinc dust comprising a retort, a condenser communicating therewith, a'second retort with a condenser communicating therewith, means providing communication between the two condensers, and valve means between each retort and condenser for interrupting communication therebetween.

JOHN F. W. SCHULZE.

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