US733741A - Method of glazing powder. - Google Patents

Description

110913337 11. PATENT-ED JULY14, 1903,:

- A. I. DU PONT.

. METHOD OF GLAZING POWDER.

. AIPLIOATIOH FILED FEB. 28,1903.

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"-NO. 733,741, PATENTED JULY 14, 1903." A. I. DU PONT. v

METHOD OF GLAZING POWDER.

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PATENTBD JULY 14; 1903.

' A. I. DU PONT.

METHOD OF GLAZING POWDER.

APPLICATION FILED 1'33. 28, 1903.

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I 9 I X PATENT Patented July 14, 1903.

OFFICE.

ALFRED I. DU PONT, OF WILMINGTON, DELAWARE.

METHOD OF GLAYZIQNG POWDER.

SPECIFICATION forming part of Letters Patent N 0. 733,741, dated July 14, 1903. Application filed February 28, 1903. Serial No. 145,635. (No specimens.)

To all whom/it mag concern:

Be it known that I, ALFRED I. DU PONT, a

citizen of the United States, residing at VVilmington, county of Newcastle, State of Delaware, have invented certain new and useful Improvements in Methods of Glazing Blasting-Powder, Gunpowder, and the Like; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in theart to which it appertains to make and use the same.

My invention relates to the manufacture of powder, and particularly to a safe andexpeditious method for glazing grains of blasting-powder, gunpowder, and the like.

The method ordinarily employed for the glazing of blasting and similar powders consists, primarily, in rumbling the grains in a rotating wooden drum or barrel. After the rotation of the drum has been continued for about ten hours, at a speed consistent with safety, the friction caused by the grains rubbing against each other and against the walls of the drum or barrel generates sufficient heat to bring to the surface the moisture contained in the grains and to drive it off in the form of watery vapor. The rotation of the drum or barrel is continued thereafter and a stream of air is sometimes passed through the drum for the purpose of carrying off the watery vapor and, incidentally, drying the powder. After the rotation is continued for some eight or ten hours longer a quantity of pluinbago is inserted. The drum or barrel is then rotated for a still further period of an hour or more, whereupon the grains maybe found to be glazed and polished. No glazing whatever is possible in this operation until the grains have given. off the watery vapor referred tothat is, the glazing operation proper does not begin until about ten hours after the drum or barrel has been put into rotation. The time required for the initial or watery-vapor generating step of the operation so lengthens the entire process that a very considerable amount of fine dust is produced, composed of particles which are rubbed off from the grains during the long rumblingoperations. Some of this dust adheres to the walls of the vessel and to the grains of powder and does now harm; but if there is any loose dust it prevents the glazing'of the 'tion of the grains for that purpose.

. grains and in all cases is the source of a corresponding decrease in the output of the process. The glazing of very small grains by the old process is only practicable by first mixing them with grains of a larger size before inserting them in the drum or barrel, attempts to glaze very small grains alone being practically ineffectual, for the reason that so much dust is produced in the operation as to prevent any glazing whatever.

The purpose of my invention is to very materially shorten the period required for glazing grains of powder, and especially the period required for the initial step of the operation, while still preserving and even enhancing the safety of the operation as a whole. By means of my improvements I am enabled to cut down the duration of the glazing process to less than one-third of the time required under the former practice, and I am also enabled successfully to glaze powders of a much smaller size than have heretofore been successfully glazed. I also effect a notable economy in the horse-power employed for rumbling a given quantity of powder, obtain an increased output owing to the lesser quantity of dust producedand the rapidity of the operation, and am enabled to successfully and safely remove the dust lining incident to the practice of the invention, as will.

. hereinafter more fully appear.

In carrying out my invention I substitute for the usual wooden drum or barrel a metal barrel provided with a jacket into which steam is admitted during the initial stage of the rumbling operation for the purpose bringing the moisture of the grains to the surface promptly instead of depending upon the fric- The watery vapor given ofi by the grains is confined within the barrel until the grains are brought to the glazing-point, whereupon the flow of steam to the jacket is interrupted and the temperature of the jacket correspondingly lowered, so that a sufficient quantity of the watery vapor'is condensed thereon to collect the dust and cause it to adhere to the inner surface of the drum or barrel, thus leaving the powder-grains clean or free from dust.

or barrel, and at the same time causing a body of cold air to pass through it, which cold air expels any remaining watery vapor, so that the product may be obtained in as dry a condition as desired.

In order to polish the powder, pulverized plumbago may be placed in the drum or barrel during the final stage of the operation.

In the accompanying drawings I have illustrated apparatus suitable for the practice of my invention and which I prefer to use, although it will be understood that I do not intend to limit myself to the employment of the specific rumble shown.

In the drawings, Figure 1 represents in longitudinal section the main body portion and journals of an apparatus suitable for the practice of my invention. Fig. 2 represents a like View, on a larger scale, of the steam and air outlet end of the apparatus. Fig. 3 represents an end elevation thereof; and Fig. 4 represents in longitudinal section, on a still larger scale, the steam and air inlet end of the apparatus. Fig. 5 represents the inlet-joint partly disassembled. Fig. 6 represents a central section through the drum.

Referring to the drawings, it will be noted that the main heads of the apparatus consist of stout castings having inner flanges a a, over which fits the metallic shell A, and flanges b 1), against which abut the sheetmetal end plates 13 O. The castings are provided with central hubs D E, forming journals for the apparatus, which journals are perforated centrally, as shown at d d, for a purpose hereinafter described.

In order to provide a steam-jacket for the apparatus, I inclose the inner shell A within an outer shell F, said outer shell being centered by means of centering-rings f. The steam-space 9 thus provided communicates, by means of piping h h, with the steam-channels i 2" of the journal D, so that by connecting the said channels to a suitable source of steam-supply a current of steam may be conducted into the steam-space 9. At the opposite end of the drum similar piping 7&2 it (see particularly Figs. 2 and 3) conveys the steam and condensed water from the steamspace 9 to the outlet-channels i of the journal E. The piping 7L2 7L3 is not shown in Fig. l for the reason that it lies in a plane at right angles to the plane in which is located the piping 7L h, as will be readily understood.

In order to permit the barrel or rumble and its journals to rotate, while still maintaining steam-tight connection with the steam supply and exhaust conduits, I provide suitable rotatory joints at the ends of the journals D and E.

The rotatory joint connecting the stationary steam-in let conduit Gwith the journal D is shown in Figs. 4c and 5. It consists, primarily, of a plate 7t, attached to the end of the journal by countersunk screws and connected by bolts and nuts, as shown, to a plate a, having an air-inlet pipe at registering with and forming a continuation of the channel (Z of Exterior to the plate a is a the journal.

grooved ring-plate r, secured by countersunk screws to the plate a, thus holding the ringplates p and 0". An annular stationary plate 5-, having an aperatu re s communicating with the steam-supply conduit G, closes the end of the plate 0". It will be evident that in this construction the conduit G and plate 3 remain stationary while the remaining parts revolve, a steam-tight connection being constantly maintained and the steam being freely supplied to both channels 1? e'. At the opposite or exhaust journal E, I preferably employ a simpler arrangement, for the reason that the pressure is lower. In this instance (see Figs. 2 and 3) the joint may conveniently consist of a single annular chamber L, secured to the end of the journal E so as to revolve therewith, with the exception of the two-part periphery t, which is stationary and within which the circular end walls of the chamber rotate. A stationary collecting-hood 4) conveys the exhaust-steam from the annular chamber, which latter is likewise provided with a pipe w, forming a continuation of the outlet channel (7/, which leads from the interior of the drum or barrel.

By the construction of apparatus described it is evident that I can maintain a substantially constant temperature within the barrel or rumble, the continuously-moving body of steam serving not only to maintain a given temperature within the barrel, but to carry oif any excess of temperature which may be generated therein during any stage of the operation.

In the practice of my invention I insert the powder to be glazed within the drum or barrel through the inlet-opening kfml then close the inlet-openin g and rotate the barrel at a speed of about twenty revolutions per minute, at the same time causing a current of steam at a temperature of about 212 Fahrenheit to pass continuously into the steam-space of the barrel and outwardly therefrom. The heat furnished by the steam soon raises the temperature of the grains to a point at which the moisture rapidly comes from the interior of the grains to the outer surface thereof. When the temperature of the grains is raised to from 160 to 170 Fahrenheit, moisture equal in amount to about from one to three per cent. of their weight comes to the surface of the grains and is given off in the form of watery vapor. This watery vapor is confined within the interior of the barrel and accumulates in sul'ficient quantity therein at about the end of three-quarters of an hour from the beginning of the rotation of the barrel, whereupon the admission of steam to the steam-space of the barrel is cut off and the barrel begins to cool. As the barrel cools the watery vapor within it condenses on the inner surface of the shell A and takes up the dust produced by the friction of the powdergrains upon each other, thus separating the dust from the grains and depositing it in a layer over the entire inner surface of the rumble. This con,-

drum is continued until the desired amount" of moisture has been driven off. At the proper time pulverized plumbago for polishing the powder is placed in the rumble and after revolving the rumble for one or more hours longer, depending on the size and kind of powder, the operation is completed, the powder-grains being both glazed and dry.

I have already directed attention to the fact that the'steam admitted to the jacket during the first hour of the rumbling operation is at boiler-pressuresay 212 Fahrenheit. This is the stage of the rumbling operation during which there is some danger of an excessive rise in temperature beyond the limitations of safety. It is not desirable, however, that the powder-grains -should attain too high a temperature; and I find in practice that, should the mass of powder approach the temperature of 212 any increasein temperaturedue rumble until the grains give oif watery vapors,

to friction'of the grains upon each other is obviated .by'reason ofv the capacity of the steam to conduct away the excess of .heat as 1 fast as it is generated. In practice it is found that by using low-pressure steam 210 Fahrenheit is the highest temperature that can be realized within the rumble when the drum is revolving at the rate of twenty revolutions per minute, this maximum limit serving as an absolute safeguard to the'operation- At the termination of the operation and after the removal of the glazed grains from the barrel the dust layer deposited upon the inner surface of the barrel is to be removed.v

This dust layer is of such thickness and solidity as to form a tubular lining to the barrel. A safe and convenientway' of removing it consists in readmitting steam into the jacket, thereby causing an expansion thereof sufficient to entirely detach the dust lining. Steam is then admitted into the interior of thedust tube thus detached, so as to soften and break downthe arch of the tube. The barrel may now be rotated for a few minutes, whereupon the detached dust lining will break up and pass through the opening 76.

The apparatus herein described is thesubject of another application for patent, Serial No. 145,536, filed of even dateherewith.

Having thus described my invention, what I claim is' 1. The method of glazing grains of powder, which consists in rumbling the grains, with the incidental production of. dust, applying heat to the inner lining or periphery of the confining the watery vapors within the rumble, then lowering the temperature of the inner lining or periphery and condensing the watery vapors thereon in quantity sufficient to take up the dust, and continuing the rumbling until the desired glazing isobtained; substantially as described.

2. The method of glazing grains of powder, which consists in rumbling the grains, with the incidental production of dust, applying heat to the inner lining or periphery of the rumble, and until the grains give off watery vapors, confining the watery vapors within the rumble, then lowering the temperature of the inner lining or periphery and condensing the watery vapors thereon in quantity sufficient to take up the dust, and continuing the rumbling until the desired glazing is obtained, in the meantime hastening the termination of the operation by expelling any remaining watery vapor from the rumble; substantially as described. 7

3. The method of glazing grains of powder, which consists in rumbling the grains, with the incidental production of dust, applying heat to the inner lining or periphery of the rumble, and until the grains give off watery vapors, confining the watery vapors within the rumble, then lowering the temperature of the inner lining or periphery and condensing. the watery vapors thereon in quantity sufficient to take up the dust, and continuing the rumbling until the desired glazing is obtained,

in the meantime hastening the terminationof the operation by expelling any remaining watery vapor from the rumble by means of a current of air, and continuing the passage of the airthrough the rumble until the grains are dry.

1. In the method of glazing grains of powder by rumbling, passing a continuous current of low-pressure steam in contact with the outer periphery of the rumble duringthe initial or watery-vapor stage of the operation; substan tially as described.

5. The method of removing the dust-lining from a glazing-rumble, which consists in expanding the rumble, so as to detach the dustlining tube therefrom, and then breaking down the detached tube; substantially as described.

IIO

' 6. The method of removing the dust-lining from a glazing-rumble, which consists in expanding the rumble, so as to detach the dustlining tube therefrom, and then softening and breaking down the detached tube by first admitting a'current of steam into its interior;

substantially as described.

" In testimony whereof I affix my signature in presence of two witnesses.

ALFRED I. DUPONT.

lVitnesses V G. A. MADDOX, WM. L. SCOTT.

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