US1961296A - Production of lead powder - Google Patents

Description

June 5, 1934.

Filed July 25, 1930 5 sheets-smet 1 IN VEN TOR. .lf-3f IIs/1 m um M W A TTORNEYS.

June 5, 1934. l.. s. lsHlMuRA PRODUCTION oF LEAD POWDER Filed July 25, 1930 5 Shegts-sheet 2 ATTORNEYS.

`Ivune 5, 1934.

` Filed July 25,'1330 L. s. Isl-"MURA H loDucTloN 0F' LEAD POWDER Y l 5 sheets-sheet 3l ATTORNEYS.

' June 5,1934.'

5 Sheets-Sheet 4 Filed July z5,` 1930 June 5,v 1934.

L. s. ISHIMURA 1,961,296 PRODUCTION OF LEAD POWDER Filed July 25, 1930 5 Sheets-Sheet 5 ATTORNEYS.

Patented June `5, 1934 UNITED STATES PArsNr OFFICE 1,961,296 PRODUCTION OF LEAD POWDER Lyuho S. Ishimura, Kamikyo-ku-Kyoto, Japan Application July 25,1930,`Serial No. 470,652

10 Claims. (Cl. 23146) This invention relates to the production of a powder specifically lead suboxide powder in an extremely dry and ne state of subdivision.

One object of the invention is to carry forward and improve certain features disclosed in the application of Shimadzu No. 104,999, led

April 27, 1926, Patent No. 1,896,020 issued Jan.

Generally spealnng, the rst of my improvements relates to the treatment of, crude lead before it reaches the oxidizing mill.

Another object of the invention isto prevent the air forced into a tumbling mill from backing out through the mill entrance or hopper and thus impregnating the atmosphere in the room where the mill is located with the fine powders since these powders particularly lead powders are more or less injurious to the health of the mill operators.

Another improvement in the invention relates to the treatment of the powder, .particularly lead suboxide powder, after it leaves the mill.

With this general statement of the objects of the invention I will now proceed to describe the same in connection with the attached drawings in which,

Figure lis a more or less diagrammatic illustration partly in section of the entire layout of my apparatus;

Figure 2 is a view partly in section of my apparatus for melting and forming the lead into bars;

Figure 3 is a plan View, partly broken away, of the mold for forming the lead into bars and feeding the bars to a cutter preparatory to cutting the lead into lumps;

Figure 4 is a View, partly in section, of the lead cutter, the mill hopper and the conveyor for carrying the lead lumps from the cutter to the entrance of the mill;

Figure 5 is a sectional view of the cutter and rollers for feeding a lead strip to the cutter and the mill hopper for receiving the cut lumps;

Figure 6 is a perspective view of the lead cutter,

Figure 7 is a view partly in section showing the interior apparatus of the mill the dust col.

lecting and powder removing apparatus;

Figure 8 is a view showing a modified form of air inlet.

Referring more particularly to Figures 1 and 2, there is shown at the right of each figure, a vessel in which the lead is melted and from which the lead issues through a spout 1 into a groove or channel 9 on the upper surface of a wheel 2 over which Vcooling water may be made to flow through a pipe marked water pipe, in yFigure 1. The water may issue from an outlet 3 into a vessel 4 from which it may run through a spout 5. l,

The lead is melted by means of an ordinary burner 6 and since the temperature of the melted lead should be kept more or less uniform,

a thermometer 7 is attached to the melted lead to indicate its temperature.v The melting pot` or vessel may have at its bottom an outlet valve to permit and regulate the ow of the lead from the vessel.

As the lead issues from the spout 1, 'it empties i into a groove l9 in the wheel 2 and the wheel 2 70 is continuously revolved lby means of power applied to a shaft 10 which operates through bevelled gears and a shaft 11 to turn a toothed, pinion -13. On the lower perimeter -of the wheel- 2 cogs or teeth may be formed adapted to mesh 75 with the pinion 13 and the turning of the pinion 13 would cause the wheel .2 to revolve in an anticlockwise direction as shown in Fgure 3.

The lead bar formed in the groove 9 as the 80 wheel 2 revolves, is carried to a scoop 14 having a pointed end 15 to extend into the groove 9 and as this scoop is rearwardlyy and upwardly inclined, from the groove 9, as shown I best in Figure l, the end of the lead bar formed in the groove 9 would be carried up over a platform 16 to and between rollers 17, 18, Figure 1, to rollers 19, 20, Figure 5. Rollers 19, 20 may be driven from 4any convenient train of operating mechanism extending from the source of power or by an independent source of power and an uppery and lower roller pull the lead bar between them and feed it to the cutter, although I preferably provide another set of rollers 19', 20 to assist in keeping the lead bar moving at 95 a uniform speed to the cutter 22 and to insure uniform pressureon the lead bar I may provide springs 17 and 18' above rollers 19 'and 19 respectively.

The lead bar, after leaving the rollers 19', 100 20', passes over a block 21 to the cutter 22. This cutter shown in perspective in Figure 6 preferably has a cam shaped periphery with a sharp edge 23 and is continuouslyv revolved to out lumps Aof lead from the lead bar as the bar is continuously fed to the cutter as indicated in Figures 1 and 5.

The lead lumps, as they are cut off, fall into a hopper 23 stationarily supportedon a standard or base frame 25, Figure 4. The mill 26 is 110 supported between the two standards and 29 on trunnions 30-31 and may have therein a pyrometer 63. The mill may be revolved by any convenient mechanism as by means of a toothed pinion 32 operating from any convenient source of power, the mill having on its ex'terior a toothed ring 34. Inside the trunnion 31 there is formed a worm conveyor best shown in Figure 4, whichas the trunnlon 31 revolves, carries the lead from the stationary hopper 23, Figure 4, to the interior of the revolving mill 26.

As the cut lumps, of lead are tumbled over and over when the mill 26 is revolved, air is forced through a stationary pipe 35 extending axially through the worm conveyor in trunnion 31 to blow out the powder resulting from the lumps of lead rubbing against each other.

The part of the pipe 35 enclosed in the mill may be made in sections 35 connected by couplings 36. From each coupling extends a nozzle 37 and the pipe 35 preferably ends in a nozzle 38 terminating at the expanded end of the trunnion 30, Figure 7.

As the air is blown through the pipe 35, it passes down through thenozzles 37 and around the lumps of lead and as the mill revolves the finely divided powder is lifted and blown from around and between the lead lumps and the air issuing from nozzle 38 blows the powder out of the mill 26, through the trunnion as soon as the surfaces of the lumps are oxidized and the powder rubbed oi by the tumbling action in the mill.

As the air passes through the pipe into the mill it produces more or less pressure in the mill and causes the air laden with the dust to tend to back out through the trunnion 31 and hopper 23 into the room in which the mill is located. To prevent this powder or dust laden air passing back through the trunnion 31 and hopper 23 and out into the room, I provide nozzles 40 inclined as shown towards the mill. It is apparent from the construction, best shown in Figure 4, that the "air under pressure in the pipe 35 and issuing through the inclined nozzles 40 as shown causes an induced draft in the trunnion which will blow any dust that might tend to back out from the mill to the hopper 23, back into the mill and thus prevent this dust from passing up out of the hopper 23 into the room in which the mill is located and cause it all to be blown by nozzles 37 and 38 outwardly through the trunnion 30. In this way I have successfully prevented the dust in the mill from passing back through the trunnion 31 and hopper 23 to contaminate the air in the room in which the mill is located. This arrangement eliminates all complicated mechanically operated valves that would be necessary to fulfill the purpose otherwise. VA pyrometer 63 of which the thermocouple is suitable placed/inside of the mill 26 as shown in Figure 7, indicates the Working temperature of the mill and is useful in controlling the temperature to keep it within desired limits. It.being understood that the temperature in the mill may be varied by varying the speed at which the mill is run or the speed at which the lead lumps are fed to the millor by varying the air supply.

The dust laden air from the mill 26 passes into a powder collecting and cooling apparatusy 45, Figures 1 and 7. This apparatus preferably comprises a vessel into which the air enters and most of the powder is deposited in the bottom of the vessel 45.

I preferably water jacket the lower part of the vessel and supply water thereto in any convenient way, as through a pipe 47. The

(water` jacket around the lower part of the vessel ytends to cool the lead powder which is composed largely of lead suboxide and pure lead and prevents rapid oxidation thereof and in the lower part of the water jacketed portion 48, I provide a screw conveyor 49 which may be run 'from any source of power to quickly pass the powder from the water jacketed portion 48 to an outlet 50 which may be conveniently covered by a valve 51 held normally to its seat around the outlet by a counter weight 52.

The screw conveyor 49 is made longer at the discharge end so that the powder filling the spaces toward that end counter balances the pressure existing in the collector 45 and prevents the powder from blowing out due to such a pressure. f

I may also arrange a pyrometer 62 so as to indicate the temperature of this collecting chamber.

In the lupper portion of the vessel 45, I may provide dust collecting bags 53, 54, 55 attached at their bottom in any convenient way to the vessel 45 to produce an air tight connection between the bottom of the bags and the vessel 45. The bags may be hung closed end up from a support 58 by hooks or otherwise and the vessel 45 enclosing the bags may have a cone shaped cover with an outlet 60 to which a fan 61, Figure 1, may be connected to draw out the air from the vessel 45. The bags 53, 54, 55 being made of fabric and attached air tight at their bottoms to Vessel 45, allows the air to pass through the fabric but said bags stop the dust on the interior of the bags which periodically may be shaken down into the bottom of the vessel 45 from which it is conveyed by the conveyor 49.

I may employ the bent pipe 35, shown in Figure 8, instead of the straight pipe 35, shown in Figure 7. 'Ihis bent pipe has on it the nozzles 40 which function as the nozzles 40 heretofore described. The modified form of pipe 35 is bent as shown in Figure 8 and has extending therefrom the nozzles 37 and terminates in a nozzle 38. Both pipes 35 and 35" are rotatable 0 in the mill 26 to vary the angle at which the air i emitted from the nozzles strikes the lead lumps as they are tumbled in the mill 26. Moreover, the nozzles 37 as sliown in Figure 8 will have theirouter ends raised and lowered on account of the bend in the pipe 35" when the pipe 35" is rotated, thus varying the distance from' the outer ends of the nozzles 37 and the lead lumps as well as the angle at which the emitted air strikes the lead lumps.

I may attach a hand 64 to the pipe which may pass over a dial 65 to indicate on the outside of the mill 26 the position of the nozzles inside the mill.

The operation of my device is apparent from the foregoing, but to summarize the operation,` lead is deposited in the melting pot and when melted runs on to the revolving disc 2 into the groove 9 from which'it is scooped by the scoop 14 and caused to pass between the guide f` rollers 17, 18 and thence to the rollers 19',v 20', ME'

19, 20 to the revolving cutter 22 which cuts lumps of lead from the bar and since the cutter is cam shaped on its periphery the" bar may Ill() be continuously moved towards the cutter and 15G the lumps will fall intoV the hopper 23 from which they' are conveyed by the hollow worm conveyor into 'the mill 26. Air is vforced by means of a blower, (not shown) or otherwise,

through the pipe and issues from the pipev 35 through the nozzles 40, 37 and 38. The nozzles 37 and 38 blowthe powder out of the mill as soon as the tumbling action breaks the powder from the lead lumps. The inclined nozzles 40 prevent the powder from coming back through the conveyor and hopper 23 and contaminating the atmosphere of the room in which the apparatus is situated. By reason of the oxidation of the lead lumps, the interior of the mill becomes more or less hot depending on the amount of lead lumps therein, how fast it is operated, and the amount of air forced into the mill. It is desirable to cool this powder, which is mostly lead suboxide PbzO, as soon as possible to prevent further oxidation of the powder to litharge PbO, so it is carried into the water jacketed vessel and cooled as rapidly as convenient thus preventing further oxidation of the powder. "The powder settling at the bottom of the vessel 45 is conveyed by the worm con' veyor 49 to the valve outlet 50 and collects on the weighted valve 51 from which it is periodically dumped into a receiving vessel. It will thus be seen that my apparatus constitutes an eflicient mechanism for converting crude lead into lead powder in a continuous operation.`

The mill should beoperated at a certain temperature limit to produce the required uniform product.

This may be accomplished either by controlling the amount of charge inthe mill or by regulating the amount of air. passing throughthe mill. But the temperature of the mill `can be more easily controlled by the amount' of charge of lead lumps into the mill. i

By using a thermo-couple 63 in the mill to indicate the temperature and employing means to cut off the motor operating the lead bar making and feeding mechanisms, when the mill temperature exceeds' a prescribed limit the temperature may be kept down. On the other hand if the temperature of the mill drops beyond its lower limit, the motor operating the mechanism may be changed to regulate the feed `of the lead lumps into the mill, thus providing for operation of the mill at any required range of temperature.

The position of the air nozzle with respect to the revolving mill is important to the effective removal of producedpowder and also to the amount of oxidation reaction. The distance of the end of the nozzles to the moving contents in the mill is important as to the blowing oi effect of the forming powder.

The adjustable nozzles provide for varying the neness of the powder and the amount of discharge product and also regulate the qualityv of the product especially the rateof oxidation of the powder. A weaker current of air discharges only a ne product and the time of retaining the powder in the mill may be lengthened to let the product become more highly oxidized.

The adjustable nozzles can be set at exactly the necessary position in my mill to get the required product by the hand 64.

What Iy claim as my invention is:.

1. Apparatus for pulverizing lumps of material and converting the lumps into powder which comprises a revoluble tumbler mill having feeding and exhaust openings therein,

means to force air into the mill to blow the formed powder through the exhaust opening, and means including nozzles in the feed opening and inclined towards the mill to direct a portion of the incoming air in a direction through the feed opening back into the mill to prevent the powder from backing out between the lumps as they are Afed to lthe mill into the surrounding atmosphere.

2. Apparatus for converting lead lumps into powder which comprises, a revolving tumbling mill lhaving'feed and exhaust openings therein,

means to force air into' the mill through the feed opening to blow the formed powder out of the mill through the exhaust opening, means to feed the lumps into the mill` through the feed opening, and means to direct some of the incoming air in a direction through the feed opening black between the lumps into the mill to' prevent the powder from backing out between the lumps as they are fed through the feed opening in the mill.

3. A revolving mill for tumbling particles of material to convert the particles into powder, said mill having an entrance opening and an outlet, a hollow conveyor for delivering the par. ticles through the entrance opening, a compressed air pipe extending through the hollow conveyor and having forwardly inclined nozzles thereon within' the conveyor to direct some of the incoming 'air between the lumps and back 105 into the mill and other nozzles in the mill to direct the rest of the incoming air against the lumps in the mill.

4. A revolving mill for tumbling particles of material to convert the particles into powder, said mill having an entrance opening axially arranged relatively to the `mill and an outlet opening, a conveyor for delivering the particles through the entrance opening, a compressed air pipe extending through the entrance opening and havingnozzles inside the mill' to blow the formed powder out of the mill outlet and also having nozzles along the interior of the conveyor to prevent the formed powder being blown cut the mill entrance opening.

5. In combination a revoluble mill for tumbling particles of material to form a powder, said mill having an axially arranged outlet, means for supplying compressed air to the mill to carry the powder through said outlet,` a vessel 125 attached to the outlet, said vessel having an outlet at its top for the airand a restricted outlet at one side of its bottom for the outlet of the powder, and means continuously operable for conveying'the powder to the outlet at 130 the side of the bottom, said outlet being normally closed but automatically openable by the accumulated powder.

6. A material pulverizing mill comprising a revoluble portion having an inlet and outlet, 135 means for forcing airthrough the mill to remove the powder formed in the mill, a. vessel having a normally covered opening in its bottom to receive the powder, said vessel being open 1 at its upper portion for escape of air and having 140 therein a bag of fabric open at its bottom and closed at its top, the lower portion of said vessel being water jacketed to quickly cool the powder as it settles in said vessel, a conveyor for removing the powder to said opening and an auto- 145 matically opened and closed cover for said opening.

7. The process of making lead powder from lumps of lead comprising feeding the lumps simultaneously blowing air into the mill to carry the formed powder out of the mill as soon as it is formed on the lumps and eroded therefrom, and blowing air into-the mill through the mass of lumps as they enter the mill to prevent the powder from backing out through the mass of entering lumps.

8. The process of making suboxide lead powder which comprises feeding lumps of lead into a tumbling mill regulating the rate of feed of the lumps by the temperature of the mill, blowing out the powder resulting from tumbling the lead lumps in the mill as soon as the lead powder is eroded from the lumps and immediately cooling the suboxide powder by passing it through a water cooled jacket to prevent further oxidation.

9. A revolvable mill for tumbling particles of material to convert the particles into powder,

said mill having an axial entrance opening and outlet, a compressed air pipe extending through said opening for blowing air into the mill bent at an angle to itself and nozzles on the bent portion extending downwardly whereby turning of the pipe will raise and-lower the nozzles.

10. A revolving mill for tumbling particles of material to convert the particles into powder, said mill having an entrance opening and an outlet, a hollow conveyor for delivering the particles through the entrance opening, a compressed air pipe extending through the hollow conveyor into said mill and alternate pipe sections and section connectors for lengthening said pipe, said connectors each having a nozzle thereon and other nozzles extending from said pipe within the conveyor.

LYUHO S. ISHIMURA.

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