[1]Patented Jm. 8, 1924. l948Op533 UNITED STATES PATENT OFFICE* WILLTA P. CLY3ffER, OF CLEVELAND, OHIO, ASSIGNOR TO NATioNAL CARBON COXPAI@Y, INC., A CORPO]ETATION OF NEW YORK. DEPOLARIZING MIXTURE AND METROD 07 PREPARING SAX3L No Drawing. Application filed September 17,1920. Serial No. 410,923. Y'o all qvhom it may e&nmrn: I Be it known that I, WILLIAM R. ('Ly@*iER, a citizen of the United States, iesidin(r at Cleveland 'n the county of Cuyabo@a-and State of blhio, have invented certain iiew and usefulImprovements in Depolarizinc, Mixtures and Methods of Prepariiig Same, of which the following is a specification. This invention relates to a depolarizing 10 mixture consisting essentialli, of man-anese dioxid and carbon in a novel state of pliysical association and exhibiting a Iii(rll degi-ee of d efficiency in d.ry (@lls of tlie' LO The inventi ' oii i-elates also 15 to arinc, sucli iiiixtui-es. xtiiy@e's for I.,e ulanch6@ eel prepared by conimingling mang id, iiattiral or artificial, with either grapbite or non-gra@hitic 20 carbon, the components bein,- pi-eliminarily grc@und and graded to a degree of fineness suitable for the purpose.in view, and the rnixture being usually mixed with s-,tl ammoniac and moistened with ele(,trolyte solu25 tion, and either tamped into the cans aroiind a carbon electrode or molded.into socalled bobbins. l@ecording to the present invention the carbon and manganese dioxid coml)onents 80 of such depolarizing mixt.iires are stibjected to a joint millidg or eqiiivalent ol)era'tion the ' preferred niilling c ' onditions I)eing as herein below described. Sal qiniyioniae is added to the resulting milled iiiixture whicii is then preferably moistened with water or with electrolyte solution. tnd eitlier tainped into the battery or mold'ed into bobbin.form according to t@e type of battery desired. I have discovered (hat for dry battery 40 purposes the joint milling of cai,l)on and manganese dioxid yields a produ(!t materiallv higber in deplorazing value than a-ny Rrocluct which I have been able to obtain by singly grinding or milling the components 45 for an equo.1 period of time, or to the same general order of fineness, and tbere,,tfter thoroughly commingling the groiincl materials. I'attribute this effect in part to the interaction during the milling operation of '30 two substances di-ffering rat'her widely in hardness and in other qualities affecting the Rrinding operation, and in part to the physical state of association of the components of the milled mixture. My preferred mixture consists of native manganese dioxid ore or pyrolusite, the qualityco'm monlyknownasphillipsbulpyrolusite liaving been found ivell ada te,5 for the urpose; and carbon. derived Flrom petrofieum coke, previouslly caleined electrically at 60 al)oiit 1600,-1800" C whereby all volitII6 matters itre expelle@ and the carbon ac-, nt iilput,, the deconductivity for iew My inven- 65 to iiie choice of materials of these particular grades or qualities. A preferred procedure in accordance with my invention is as follows, it being under- 7') stood that the invention is iiot restricted to t-lie specific riianipiilations or to the particular qualit,y or pi-o ortion of components described by way opexample: Petroleum coke,, calcined as above de- 75 scribed.and crushed in a Teffrey or other ptilverizer to pass a one-fourtli inch opening is iriixed witli pyrolusite, previously ertished to pass a 30 niesli screen, as for example by Sturtevant rolls. The resultiiig mixture is 80 then niilled for several hours in a pebble mill or eqtiivalent device for mechanical reduction. Either dry or wet milling may be employed, the formed being preferred. Satisfactory results li,,tve I)een obtained for in- es stiince by 4-7 liotirs milling in an Abl)e #7 pebble inill, at, iboiit 36 revolutions pel@ miiitite. Uiider these (!otiditions, the carboii, bein- the softet- component, or at aily rate undergoincr the iiiore rapid rediietion in size, go apl-)ears to coit t lie pi,@olusite particles, witli the result th,,tt ther@ is established between the carbon and p3,i-olilsite components an extreme intima(@y of contact as well as a highIY favorable surface-exposure relation. 95 Also, the resiilting mix possesses a felotively high absorptive ca'pacity for electrolyte solution. Batteries prepared from these mixtures have shown seri,ice results materially better loo than are obtainable from the same materials separatelv (,@round -and intimately mixed; ,tnd also service results equal to or better than those obtainable with graphite or other expensive forms of carbon of extreme finb- log ness. Wlie-n the raw materials are pyrolusite and highly cal(-ined peti-oleum coke, and the dry bqiteries are o-f the so-called midffet type, a mix ratio approximately 2 parts of pyro- 110.
[2]lusite to I part of coke rep'resents the optimum with respect to initial amperagc, and service. Materially higher ratios of pyroltisite, for example 3: 1 afford excelleiit service bitt the initial amperage is undesirably low; -%vhile rnaterially lower pyrolusite ratios, for example 1.4: 1, give excelle-it initial anipei-a-es, but the service. although good is inferior. to that obtainable with the 10 iligil@r pyrolusite content. For batteries of the SIX-inch type, a pyrolusite carbon ratio of the brder of 1.4: 1 is satisfactory. However my inveniion is not. limited to the employment of the iiian,-,anese dioxid and car15 bon in any particular proportions, especially since these prportions may vary considerably according to the natui-e of grade of the inan-anese dioxid and carbon components tD used, and witli-the size and service, require20 ments of the cells in which the mix is used. The desirable state of divisio@n of the components of the mixture to-be milled will naturally vary -",ith the quality or character 25 o@ these components, and also in a measure with the mil'ling facilities available. As a general rule however the best results are secured when the carb6n is iiiitiary in a coarser state of subdivision than the pyrolu30 site. In the milled product, on the other hand, a considerable proportion at least of the carbon component exists in a -very fine state of subdivision 9 the rate of subdivision being greatly accelerated by the presence of the harder particles of pyrolusite. .3 While I have referred above to highly calcined petroleiun coke and native mano,anese dioxid as the'commercially desirable raw materials for use in connection with the 40 present invention, it is to be understood that other forms of carbon and madganese dioxid may be employed without departure from my invention. Thus for example the pyrolusite may be replaced wholly or in part by 45 artificial manganese dioxid; and similarly the highly calcined petroleum coke may be replaced wholly or in part by other fully shrunk a-nd suitably conductive forrns of carbon, or by gr'aphite. 1,480,533 I
