US832829A - Magnetic separator. - Google Patents

Description

PATE-NTED OCT. 9, 1905.

H. H. WAIT. MAGNETIC SEPARATOR. APPLIUATION FILED APB.24,1905.

2 SHEETS-SHEET 1,

No. 832,829. PATENT@ 00T. 9,v 19116. H., H. WAIT. MAGNETm-SEPARATUR. APPLIGATOH FILED ATR. 24,1905.

UNITED sTATns PATENT orrion i HENRY H. WAIT, OF CHICAGO, lLiilNOI-S, ASSIGNOR TO INTERNATIONAL SEPARATOR COMPANY, OFCHIOAGQ ILLlNOIS, A CORPORATlON OF NEW JERSEY.

MAGNETIC SEPARATOR. 'l

Specification of Letters Patent. i'

Patented Oct. 9,1906.

Application iiled April 24.1905. Serial No. 257,047-

Toalll whom, zt may con/cern: Be it known that I, HENRY H. WAIT, a citizen of the United States, residing at Chicago, inthe county of Cook and Stateof Illinois, have invented a certain new and useful Inilprovemcnt in Magnetic Separatore, of which the following is a hill, clear, concise, and exact description. i My invention relates toi a magnetic separa- Io tor; and its object is to improve the design of' the magnetic parts so as to secure the most effective separation of materials of very low permeability with a minimum expenditure of energy.

I 5 More particularly, my invention contemplates an improved form and disposition of the magnet pole-pieces and improved forms and proportions of the armature-teeth, such as to secure the inost eective magnetic atze traction of the ore particles'of any given size.

In other words, one feature of the invention looks toward thedetermination of definite relations between the size of the particles to be attracted and the size and shape of the z 5 magnetic teeth to secure thebest results.

V I will describe my invention by reference to the accompanying drawings, in which- Figure .l is a sectional elevation of an ore separator embodying said invention. Fig. 2

3ois a detail cross-section oi' the portion of the armature-surface, `showing the manner in which it is built up. Fig. 3 is a detail view of a portion ofthe armature looking at the sides of the teeth. Figs. 4 and 5 are side views of 3 5 teeth of other forms. Fig.' 6 is a diagram illustrating the influence whichthe shape oia magnetic projection or tooth has upon the attractive force exerted upon an ore particle in contact therewith. Figs. 7 and 8 are dia 4o grams illustrating the influence which the shape and size of the end et the tooth has upon an ore particle of given size, Fig. 7 indicating the tooth too sharp ior the .ore particle v and Fig. 8 the tooth too blunt for the ore particle of the relative size indicated. Fig. 9

lis a diagram of curves indicating the varying force of magnetic attraction produced upon an ore particle of given size by teeth, the ends of which have dii'lerent radii of curvature.

The same letters of reference are used to designate the same parts wherever theyv are shown.

In Fig. 1 I have illustrated an ore-se aratiiig machine ofthe general type in wliich a der.

cylindrical armature having teeth upon its periphery is arranged to rotate upon a horizontal axis between two magnet-poles of opposite polarity facing opposite sides oi said armature. The machine is provided with the usual feeding mechanism for passing inaterial to be separated onto the upper surface of the cylinder, whiclriii its rotation carries the material through the ,air-gap between said cylinder and one of the magnet-poles S..

The machine* is provided witlrniagnetizingcoils'a c, through which a current is passed sufficient to setup an intei'ise magnetic flux passing from one magnet-pole to the other through the cylinder@ The air-gap between the cylinder 'and' the nnignet-pole S is the working-air-gap, through which the ore to be .separated is passed, while the magnet-pole N tliepole-piece N and the armature maybe of less length than the working air-gap in order to economize niagnetining force. This area is also greater than that of the working pole for the sainevreason'. This area cannot be indefinitely increased, however; but the areas of the two opposing pole-pieces should be so adjusted with reference to the air-gaps that the pull oi' the pole N plus the working strain on the shaft will approximately balance the p ull of the working pole S.

Referring to Fig. 1, it will be seen that the mixture of material passinvibetw'een the surface of the cylinder and the inagnet-pole S will be .subjected to an intense magnetizing force tending to pull over the more peime* able particles toward the surface of the cylin- The cylinder is provided with teeth or permeable projections upon its periphery for the purpose of securing convergences .of the lines of oice toward the cylind er, so that the forceoi attraction, which'is generally along converging lines of force, will be toward the 'cylinder rather than toward the stationary oleepiece". The non-magnetic material, be-

ing unaffected, will fall straight down over the edge of the'ylinder, while the magnetic material will ten to follow the cylinder in its IOO i rotation through a short arc below' the ,horithrough the same, which is useful zontal plane through the axis. In the case of ores of very low magnetic permeahilitv the magnetic field., however strong, will only be sufficient to hold the attracted material to the armature througha very short are below the horizontal plane, because as the 4material is carried around in the path determined by' the rotation of the armature the force of attraction will act against a constantly-in creasing component otgravity andV in a rapidly-decreasing magnetic field, A dividerplate b is therefore placed inposition so that its edge will be close to the under side of thev cylinder and referably just insidel a vertical tangent Vto t e cylinder. The divider, in other words, is so placed that the magnetic material will be carried beyond its edge, while the non'-1nagnetic material will fall outside.

While the separating-cylinder is of considerable diameter, as shown', the niaenetic flux iior separation, must for the foregoimr reasons be concentrated as much as possihle along a short arc'just below the horizontal plane through the axis of the cylinder; but the frame. of the machine constituting the magnetic circuit should be of large cross-section in order to present the minimum reluctance to the magnetic flux, and so to require the minimum expenditureof'energy for magnetization. For

' the foregoing reasons l therefore cut awaitr the pole-piece S sharply just above the hor1- y as shown in the drawings.

" which are concerned With'the size, shape, ad

Corning 4now-to the features of invention proportions ofthe magnetic teeth by which the most effective attraction is secured, reference will be had to the diagrams Figs. 6, 7, and 8. The attractive forcel exerted upon an ore particle of's-light susceptibility is dependent upon three factors: its magnetic susce tibility, the total magnetic flux through t e particle, and the anglesof convergence of the ines of force threading through the particlefi. e., the rate of change in'densitv of the-field occupied by the particle. Fig. 6 illustrates a spherical ore particle d in position to be attracted by a sharp-pointed magnetic tooth e,

and also shows in dotted lines the manner in ceases i' tooth'gives the host results may hebriely given as follows.: In magnetic separators oil the type under 'consideration the density'oi the magnetic flux through the teeth at the working gap is verv hi h, the teeth being Eracticall saturated. hor'such very stron elds the ine of maximum attracting strengt of the field lies not at the extremepoint et point. In general, the outline of the and oil,

the'tooth should conform approximately in shape to the imaginarye uipotential surface lying back ofthe rea surface of the tooth.v It will be evident from the foregoin however, that the size and shape of the toot should be proportioned to the size o'theore particle to be attracted, and that in general or small particles the tooth should be sharper than for large particles. in Fig. 7

an ore particle is indicated in position to be attracted by a comparatively sharp tooth. By reference to this diagram it wiil he ssen that the lines of force threading the particle diverge widely,'which in itselt'is desirableA but 'which in this case is accompanied oy a decrease in the total ilux through. the parti-f cle, so that the maiiimum attractive'ores is the tooth,l but some distancebaclr, and the not obtained. The o posits condition is in V dicated in Fig. 8, whic i illustrates an oreparL ticlerof the same size as that cig-Figs. 6 and 7 in contact with avery large blunt tooth,

this case thetotal 'Hux through thev article is great; but the convergence of the infra oi* force is.so slight that the' actual attractive force tending to pull ,the particle toward the tooth is comparatively slight. lt is evident.

that between the small sha1 tooth indicated in Fie'. 7 and the very large lunt'tooth indicated by Fig. 8 there may be determinedthe size and shape of toothwhich when magneticallysaturated will exert the maximum ate tract-ive force -upon the ore particle of given size.

In Fig; 9 are shown two ticle of unit size yby conical magnetic teeth having rounded blunt ends ofvarying one vatures. j In this diagram the vertiealdis tanceindicates the relative strength of the y magnet-pole tips in units of theradius of the particle which is attracted. The lux densityv at'the surface of 'the pole-tip vis-the same' throughout. The curve Z in icates ro l curves which mell- A cate the attractive forces exerted apenaparsuits with hematite ore, which is of low magnetic susceptibility, and the curve m indi- ,c'at-es they results with magnetite, a highly- {niagnetic ore. result of actual tests.

These curves represent the It Will be seen that in e'ach case the maximum attractive effect is f produced When the rad1us of curvature of the ically.

dent that the constructor can at once determagnet-pole tip is approximately two and one-half times-the radius of the ore particle.

The same rule can. be worked out mathemat- By applying this rule it will be evi- "mine the best size and shape of teeth to be conditions are obtained with a conical tooth having a smooth rounded end, these conditions are approximated .by the use. of teeth having generally yramidal or conical sha e with blunted ends slighty larger than tile particle to be attracted. t may not be practicable mechanically to form the teeth in the ideal shape; but in Figs. 2 to 5, inclusive; I have indicated some forms which maybe convenient in practice.

It is practically necessary that the armature or separating cylinder should be transversely laminated in structure in order that it may be turned easilyin the intense magnetic field, and to avoid the heating effects of eddy-currents, and such a laminated construction lends itself readily to -the formation of a toothed attracting-surface such as vcontemplated by this invention.

In Figs. 2 to 5,1 have illustrated the surface built up of magnetizable plates having toothed edges, vthe teeth of adjacent plates being of progressively different heights, so that` projections of generally pyramidal shape are thus built up. In the specific form shown in Figs. 2 and 3 4the teeth of one set of disks are quite vlong with rounded l ends, While the teeth of adjacent disks are cut oil more and more at their ends, though coinciding in outline and position of their bases. In the form shown in Fig. 4 the teeth of adjacent disks have their ed es cut at progressively different angles. n the form shown in Fig. 5 the teeth of adjac nt disks going to build up the projections are progressively larger or smaller, but having their edges out at substantially the s 1e angles. It will be seen that in this construction the main projections built n/p by the teeth of a number of adjacent disks Will serve to attract large particles of ore, While very small particles which may be in the mixture will bev caught by the smaller teeth of individual disks.

Having thus described my invention, I claim- 1L In a magnetic separator, an clement having a magnetic attracting-surface provided with a num-er of approximately pyramidal rejections each composed of a plu- 'l'alit oi) teeth of progressively different 2. A se arator-cylinder having its surface formed o transversely-disposed magnetizable plates having teeth upon their edges, the teeth of adjacent plates being of progressively different heights to form approximately pyramidal projections upon the surface of the cylinder, the points of said projections being blunted, substantially as described.

3. In a magnetic separator, an'element having a magnetic attracting-surface provided with a number of projections each composed of a plurality of teethof progressively different heights, the points of" said pro-` jections being blunted, and means for magnetizing saidteeth to saturation.

In witness whereof Ihereunto subscribe my name this 17th day of April, A. D. 1905.

HENRY H. WAIT.

Witnesses:

DE Wrrr C. TANNER, IRVING MACDONALD.

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