US2146033A - Handling of sensitive materials - Google Patents

Description

Feb. 7, 1939. F. R. SEAVEY ET AL 2,146,033

HANDLING OF SENSITIVE MATERIALS Filed Feb. 28, 1935 Patented Feb. 7, 1939 HANDLING OF SENSITIVE MATERIALS Frederick R. Seavey and Edward B. W. Kcrone,

Alton, 111., assignors to Western Cartridge Corporation, East Alton, 111., a corporation of Delaware Application February 28, 1935, Serial No. 8,598

4 Claims.

This invention relates generally to the handling of sensitive or hazardous materials, such as explosives and particularly to a process of dehydrating such materials without permitting them 5 to become free of desensitizing or deterrent liquid.

' Most explosives are purified, manufactured, or precipitated in aqueous solution and it is highly desirable particularly with reference to highly sensitive explosives and other hazardous materials, such as mercury fulminate, lead azide, lead styphnate, powdered zirconium and the like, that these materials be maintained in a wet condition during the manufacturing and mixing processes and in fact until they are deposited in the final housing or component. As pointed out in the prior copending application, Serial No. 595,418, filed February 26, 1932, now Patent No. 2,000,995, patented May 14, 1935, of which this application is a continuation in part, the use of water as the wetting medium has the disadvantage that the water evaporates rather rapidly so as to leave particles of the explosive in a dry and hazardous condition. In the application mentioned, a process is disclosed whereby the water with which sensitive materials are wet may be removed by first washing the water-wet material with a liquid, such as alcohol which is miscible with water until the water is removed from the sensitive materials and thereafter replacing the alcohol with a relatively non-volatile medium such as dichlor-ethyl ether.

It is among the objects of the present invention to provide a process of handling water-wet materials whereby the materials may be transferred directly from water to a medium of relatively low volatility without an intermediate'drying stage.

A further object of this invention is to provide a process of rendering hydrophilic materials organophilic.

Another object of this invention is to provide a process and apparatus for dehydrating organophilic materials without permitting them to dry.

Another object of this invention is to provide a process of handling sensitive or hazardous materials whereby the materials may be transferred directly from water to a liquid vehicle of com- 50 paratively low volatilitywithout an intermediate relatively hazardous stage.

A more specific object of this invention is to provide a process and apparatus in which a hydrophilic explosive may have its surface modifled so as to become organophilic and thereby facilitate replacing the water directly with an organic medium.

Other objects will become apparent to those skilled in the art when the following description is read in connection with the accompanying drawing illustrating elemental apparatus suitable for carrying out the processes of the present invention.

Figure 1 is a diagrammatic view showing one form 'of apparatus for carrying out the processes of the present invention.

Figure 2 is a diagrammatic view showing a. modified form of apparatus for carrying out the processes of the present invention.

Figure 3 is a view more or less diagrammatic in form showing a centrifuge particularly adapted for carrying out the processes of the present invention.

In accordance with the present invention, generally stated, a sensitive material which is nor- 2 mally water-wet and which in addition has. a surface hydrophilic in character, that is to say, is preferentially wet by water rather than by certain organic liquids, may be treated with an agent capable of so modifying the surfaces of the particles that their surfaces become organophilic. With the surface thus modified the water with which the material has been wet may be readily removed by incorporating the mixture with the organic liquid which it is desired to employ. After thorough incorporation, if the mixture be permitted to stand, the particles of sensitive material will become entrained in the organic liquid while the water segregates so that it may be separated by decantation, centrifuging, or otherwise. Moreover centrifugal separation may be accomplished inmiediately after incorporation. Such explosive and sensitive substances as lead azide, powdered zirconium, etc., are normally hydrophilic. In accordance with the present invention, however, these materials when treated with long chain fatty or long chain unsaturated acids, such as palmitic, stearic, oleic, linolenic, or linoleic acids, etc., or by soluble soaps, appear to have their surfaces modified so that they become organophilic and hence the water in which they are incorporated may be directly replaced by an organic liquid having the desired properties such as a lower volatility than water and a greater protective action generally. Examples of such organic liquids which may be advantageously used in connection with such explosive and sensitive materials are dichlorethyl ether, tetrachlorethylene, trichlorethane, and tetrachlorethane.

acid over the lead azide particles.

Such organophiiic-coat-producing agents as the long chain fatty and long chain unsaturated acids and their alkali soaps may be applied to the explosive materials in various ways. For instance, the long chain fatty and long chain unsaturated acids may be emulsified in water and this emulsion incorporated in a water slurry of the explosives. In the case of the soluble alkali soaps of these acids, however, a solution thereof may be made with water and this solution incorporated with a water slurry of the explosive. As another alternative, either the acid or the soap may be incorporated in the organic liquid which is subsequently to be mixed with the water slurry of the explosive. In each instance, however, care shouldbe taken to sumciently incorporate or mix the media containing the organophilic-coat producing agent so that each particle of the explosive is contacted with that agent. Emulsifying agents may be used to facilitate the preparation of suitable emulsions when advantageous.

Such organophilic-coat-producing agents appear to react slightly with the material so as to produce a heavy metal soap of the acid employed upon the surface of the particles of the material. An extremely small proportion of organophiliccoat-producing agent is necessary in order to produce a coating which, for the purpose, obviously may be extremely thin. Since such heavy metal soaps are readily wet by organic liquids but are not wet by water, it will be understood that the particles of explosives are rendered organophilic so that when an organic liquid is incorporated with the water slurry of the explosive the particles, being preferentially wet by the organic liquid, desert the water or become enveloped by the organic liquid so that a suspension of the explosive in the organic liquid results.

As a specifie illustration take, for instance, water-wet lead azide as the material to be treated, dichlorethyl ether as the organic liquid, and oleic acid as the organophilic-coat-producing agent. One part of lead azide suspended in ten parts of water may be treated with a water emulsion of oleic acid containing 0.75% oleic acid (based on the dry weight of lead azide) and one part of water. The emulsion may be added to the lead azide-water slurry and vigorously agitated in order to assure an even distribution of. oleic To this mixture may then be added ten parts of dichlorethyl ether (the organic liquid) and the entire mixture ethyl ether.

As another embodiment instead of employing the emulsion of oleic acid as described above, a

solution of sodium oleate, triethanolamine oleateor other water soluble soap containing about 0.75% of'oleate or other long chain unsaturated or fatty acid in water may be substituted. In

'this case, as in the example above, upon the addition of the organophilic-coat-producing agent the lead azide slurry is thoroughly agitated so as to assure even distribution thereof. Thereafter the organic liquid, such as dichlorethyl ether, maybeadded and the excess liquid removed as in the previous illustration.

As another specific example the organophiliccoat-producing agent may be directly dissolved in the dichlorethyl ether. For instance, a solution may be made in ten parts of dichlorethyl ether containing 0.75% of oleic acid (based upon the dry weight of the lead azide) and this solution incorporated directly with the lead azide water slurry. The agitation and separation steps described above are again carried out.

Normally organophilic explosives which have become wet with water may be dehydrated by drowning in a bath of organic liquid, or otherwise incorporating sufficient organic liquid to displace the water.

As illustrating the dehydration of mercury fulminate, for example, a slurry composed of 100 parts of fulminate in 500 parts of water may be treated with a solution of 1 to 2 parts of potassium ethyl xanthate in 10 parts of water. The xanthate solution is thoroughly mixed with the slurry and thereafter about 500 parts of dichlorethyl ether may be mixed in. The fulminate then settles with the dichlorethyl ether and the water may be decanted on. Of course, other organophiliccoat-producers, as described above, may be used instead of potassium ethyl xanthate.

Referring now particularly to the drawing for an illustration of various forms of apparatus suitable for carrying out the processes of the present invention the apparatus shown in Figure 1 may comprise a receiving jar I and a mixing vessel 2. As shown, the mixing vessel is formed as an inverted cone having a neck 3 which extends into the receiving jar. A suitable stopper 4 may be provided for sealing the space between neck 3 and the neck of jar I. Another stopper 5 is provided for closing the neck of mixing vessel 2 on the inside and this stopper may be conveniently provided with a long rod 6 by which it may be readily seated and unseated. A suitable agitator I is also provided.

In carrying out the invention in accordance with this embodiment jar I may be filled with the organic liquid such as dichlorethyl ether to a level such that the end of neck 3 will be submerged and stopper 4 may then be inserted so as to leave.

a small air space between the level of the liquid and the stopper 4. Additional dichlorethyl ether is now poured into dehydration vessel 2 so as to fill neck 3 and the stopper 5 is then inserted.

After stopper 5 is inserted the desired amount of dichlorethyl ether, such for instance as sufiicient to extend up to level 8, may be added. The water slurry containing the explosive such as lead azide may now be placed in vessel 2 so as to bring the level thereof up to 9. Agitation is now begun, it being understood that, the organophilic-coatproducing agent is included in either the organic medium placed in vessel 2 or in the slurry as hereinbefore described. The agitation may be continued until all of the lead azide has settled into the organic liquid. In case the water and organic liquid tend to emulsify, slow agitation in the interface will be found to break the emulsion and if globules of water become occluded in the organic liquid, they may be freed by upward agitation in the organic liquid face. When the lead azide has all settled from the water phase to the organic phase, stopper 5 may be removed so as to permit the azide to settle further down into the receiving vessel I leaving the water above level 8.

A modified form of apparatus in which separation of entrained occluded water is more certain is illustrated generally in Figure 2. In accordance with this embodiment a receiving jar l l is provided as before. Into the mouth of receiving jar II is fitted an immersion vessel Ill provided with a neck l3 and a stopper I5 having a control rod I50 for the interior thereof. Within the immersion vessel I is contained a smaller mixing vessel l2 which, as in the previous embodiment, is provided with an agitating device I! and a stopper 16 for mouth I20.

In the use of this form of apparatus the receiving jar and the immersion vessel are filled with dichlorethyl ether and, as in the previous embodiment, stopper i is seated. The stopper it in mixing vessel i2 is also seated and additional dichlorethyl ether is poured therein so as to bring the level thereof up to l8. Upon the dichlorethyl ether in the mixing vessel may be poured the water slurry so as to bring the water up to the level l9. In the use of this apparatus the incorporation and agitation is accomplished as before, but when the lead azide has settled into the organic medium, stopper 5 is removed so as to permit the same to pass into the dichlorethyl ether contained in immersion vessel l0 and here again the mixture stands until the lead azide settles to the bottom. During this settling period it will be understood that opportunity is afforded for globules of entrained or occluded Water to segregate and rise to the top in immersion vessel I0. It may also be pointed out that the various vessels may be made of glass or so arranged that the levels of the liquids may be ascertained.

When the azide has finally settled in immersion vessel l0 stopper l5 may be lifted to permit the same to be further settled into the receiving jar ll. After such settling stoppers l5 and I5 may be replaced and jar ll removed.

Another form of apparatus which may be used is shown in Figure 3. In this case one or more cups 20 may be suitably mounted as by a support 2| to a shaft 22 which may be rotated. Cups 20 may be pivotally connected to support 2| as shown at 23 so as to permit them to swing into the dotted line position upon rotation of the shaft. It is also convenient to mount the cups so that they may be readily removed. Cups 20 may be provided with a suitable lining such as rubber.

In the use of this form of apparatus, for example, the water wet slurry of explosive is placed into cups 20. The required amount of oleic acid is then added as a water emulsion with stirring,

followed by the addition of the required amount of dichlorethyl ether also with stirring. The rubber cups are then placed in the centrifuge and centrifuged slowly to break the emulsion and release the occluded water, after which the centrifuge is turned to higher speed for the required length of time to pack the explosive to a paste of the required solids content. If found desirable in order to remove final traces of water which may be occluded, the explosive may be resuspended in fresh dichlorethyl ether and recentrifuged. The paste thus obtained is then ready for storage or use.

From the foregoing description it is apparent that processes hereinbefore described accomplish the objects of the invention and that waterwet explosive may be dehydrated in accordance with the present invention by direct replacement of the water with a suitable organic medium. As pointed out hereinbefore for the handling of explosives, dichlorethyl ether, tetrachlorethylene, trichlorethane and tetrachlorethane are ideal because they are relatively difficult to ignite and of considerably lower volatility than water and minate, lead styphnate, basic lead azide, nitrosoguanidine, tetracene, guanyl tetrazyl triazene, potassium azinol, basic lead styphnate, lead and silver azinol, powdered zirconium, etc. In these cases except the latter, water is present from the manufacturing operations since with 5 these materials some stage of manufacturing, purification or precipitation is conveniently carried out with the substances in aqueous solution. In the case of zirconium powder, however, this material may be produced by wet grinding and it will be understood that the Water from the grinding operation may be supplanted with a suitable organic medium, such as dichlorethyl ether, either directly in accordance with the present invention, or indirectly by the use of an intermediate washing with alcohol as described in the copending application Serial No. 595,418. 1

For instance direct dehydration of zirconium powder may be facilitated by a preliminary activating treatment using a substance which will bind the organo-philic-coat-producing agent to the surface of the particle. Silver nitrate may be employed as the activator in this case and thereafter either oleic acid which for convenience may be in an alcohol solution or potassium ethyl xanthate in aqueous solution or other suitable agent may be applied as above described to produce the organophilic coat which enables the organic liquid to envelope the particles. Direct dehydration of nitrosoguanidine, tetracene and guanyl tetrazyl triazene is readily accomplished by using activators. Lead nitrate and nickel nitra'te are particularly useful when the aqueous suspension of these materials is made slightly ammoniacal.

Such activators may be used with advantage wherever an organophilic-coat-producer which will react with the solid is not at hand. Even with some materials which can be dehydrated without activators, the operation is expedited by the use of activators.- In such cases the activator may react with the solid to produce a film with which the other agent may react to produce the surface condition.

The organic liquid employed for desensitizing 55 should be selected so as to avoid solution of the coats on the solid or the solid itself. For instance, in dehydrating potassium azinol using lead nitrate as the activator, a coat of lead azinol is produced. Since this coat is somewhat sol- 60 claims, as well as similar expressions which may 70.

be found therein, it is intended to include those substances which either by surface reaction or adsorption convert the surface of the particles of explosives from a character in which they are preferentially wet by water to a character in themselves to those skilled in the art, it is to be; distinctlyunderstood that the invention'is not limited to the details of the processes and apparatus herein disclosed, but that such modifications and the use of such individual features and subcombinations of features as do not de--' part from the spirit of this invention are, al-

though not specifically described herein, contemplated by and within the scope of the appended claims.

Having thus described the invention what is claimed is:

In'the art of handling explosives having a highorderof sensitivitysuch as lead azide and 'which are unsafe for handling inthe form of 1 water-wet paste, the process comprising, providing a water slurry of the explosive, adding to the, slurry an organophilio coat producing substance,

? "incorporating an organic liquid which is inert to the explosive, less volatile than and immiscible with water, and removing the water;

' 2. The art of handling explosives having a high orderofsensitivity such as lead'azide and which are unsafe for handling in the form of water-wet paste, the process comprising, providing a water slurry of the explosive, adding to the slurry an organoph'ilic coat producing substance of the class consisting of alkali xanthates,

long chain fatty acids, long chain unsaturated fatty acids and water soluble soaps thereof, .incorporating an organic liquid which is inert'to the explosive. less volatile than and immiscible withwater, and removing the water. l

3. In the art of handling explosives having a high order of sensitivity such .as lead azide and which are unsafe for handling in the form of water-wet paste, the process comprising, providing a water slurry of the explosive, treating the i explosive with a metal activator, treating the,

activated particlesof explosive with an agent whose reactionproduct with the activated surface of the explosive is organophilic, incorporat ing an organic liquid which is inert to the explo- =sive, less volatile than and immiscible with water,

and removing the water. a

. 4. In the art of handling explosives having a high-orderof sensitivity such as-lead azide and which are unsafe for handling in the form of water-wet paste, the process comprlsing,.pro-- viding a water slurry of the explosive, adding to the slurry an organophilic coat producing substance, incorporating an organic liquid which is inert to the explosive, less volatile thanand im product to obtain a paste wet with the organic liquid, and removing thewater.

FREDERICK- RQ SEAVEY.- EDWARD n. w. moms.

-miscib1ewithwater, centrifuging the resultant

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