US1584149A - Method of manufacturing metal powder - Google Patents

Description

Patented May 11, 1926.

UNITED STATES ennzo snmanzo,

or xYo'ro, JAPAN.

METHOD 0! MANUFACTURTNG METAL POWDER.

Io Drawing.

The present invention relates to a method of manufacturing fine powder of a plastic metal, by putting the plastic metal .such as lead, in pieces in a rotatable vessel, and rotating the vessel so as to cause friction of the metal lumps with each other and with the inner surface of the vessel thereby ef fecting the abrasion of the metal pieces. The object of this invention is to manufacture spongy chemically re-active, fine lead powder by a simple and cheap process without crushing the same as has hitherto been the case.

Hitherto, the manufacture of metal powder has been done either by crushing or grinding the material or by a method, as in the case of manufacture of zinc dust, which consists in cooling a mixture of zinc vapour with air so that the metal coagulates into a fine powder.

The products of these old processes, however, are coarse-grained and liable to harden on the surface layer. Besides, while the particles of the powder obtained by crushing or grinding are generally pressed fiat and are therefore with diificulty acted upon by chemicals, the powder obtained by atomizing and cooling process is only a relatively coarse product, which is not chemically reactive. Also the powder which is obtained by filing is not only coarse-grained, but is liable to be impaired in its purity by the mixture of the particles which wear off from the files themselves.

Thus the former products are not best adapted for use in special chemical purposes, which are aimed at in the present invention.

The present invention consists in rotating a rotatable vessel, containing lumps of metallic lead, in such a manner that the metal lumps rub against one another, and the inner surface of the vessel, causing abrasion and pulverization of the lumps. The degree of fineness of the powder can be regulated by regulating the quantity of the metal lumps put in the vessel.

To give a practical example of manufacturing lead powder according to the present invention;

A circular hollow cylinder made of iron, inches in diameter and 60 inches in length, is horizontally and revolubly mounted. Within this cylinder is fitted an airblower provided with small holes. Through one end of the cylinder is provided an orifice Application filed January 30, 1922. Serial No. 532,920.

for feeding it with the material, and .at the other end, an orifice to discharge the product.

The cylinder is, at the start, filled with 500 balls of steel, 1 inch in diameter, together with 1,000 kilograms of lead balls of 1.5 inches in diameter. As the abrasion is going on, the cylinder is replenished with lead ball continuously and at a definite speed at a rate of 100 kilograms an hour, while air blast having a pressure of 2.5 pounds per square inch, is sent out of the air-blower. The cylinder is caused to rotate at a rate of 15-25 times per minute. account of this rotation of the cylinder, the lead balls contained therein get abraded and pulverized .into very fine powder, which is blown out of the cylinder through the discharge orifice by means of theair blast from the said blower, and the lead powder thus blown out is led into a suitable chamber and collected there. By this operation, 100 kilograms per hour of fine powder with an apparent specific gravity of about 2.1 is obtained. The above described arrangement may be modified, and instead of providing a separate discharge passage, the cylinder body may be pierced through all over with 0 small holes, whence the powdered product may be blownv out to be collected in any suitable chamber.

The lead powder thus obtained is very fine and has an extensive surface so that its apparent specific gravity may be made, in some cases, even smaller than 1. It easily oxidizes and spontaneously ignites, so that it is necessary to provide with a cooling apparatus to radiate the heat generated by friction, when treating easily oxidizable metals, such as lead.

In short, the present invention does not crush, grind 0r file metals, but reduces them into powder by abrasion, pieces of the metal to be pulverized being put in a slowly rotating vessel, and caused to rub against one another and the wall of the vessel. The principal advantages of my invention over the hitherto known processes are as follows 1. A small amount of power is required; the process is simpler; and the fineness of the product can be regulated as desired.

2. A very high degree of fineness can be attained, without impairing the purity of the product.

3. The product being spongy and having extensive surface, has a strong chemical reactivity. It often oxidizes in the air and spontaneously ignites. It is therefore most suitable for chemical purposes and is economical too.

4. The product oxidizes at a low temperature, but its catalytic action is very strong due to its extensive surface and consequently is very useful as a catalyzer,a depolarizer of electric battery, a reducing agent, or

as an oxygen carrier.

and forming said lead owder by attrition of said lead masses resu ting, from the rubbing of said masses against each other.

2. A method of forming a finely divided chemically reactive lead powder of such fineness and activity as to be readily changed chemically on ex osure to air, which comprises introduclng relatively large masses of lead into a rotatable vessel, rotating said vessel at a relatively low speed, introducing a current of air into said vessel, forming said lead powder. by attrition of said lead masses resulting 'from the rubbing of said lead' masses against each other, and removing the said powder from said vessel by means of said current of air.

In testimony whereof I have aflixed my signature.

GENZO SHIMADZU.