US2345474A - Ore mill - Google Patents

Description

Patented Mar. 28, 1944 UNITED STATES PATENT OFFICE ORE MILL Frank J. Haverland, Deadwood, S. Dak. Application November 19, 1941, Serial No. 419,799

4 Claims.

This invention relates to a complete grinding, jigging, classifying and froth flotation unit, which can be additionally employed as an amalgamator by the addition of quick silver or mercury.

It is a primary aim of the invention to pro-- vide a grinder which produces comminution with a minimum of power due to the elimination of power losses caused by stress on pins, pivots, gears or bearings; by substantially eliminating abrasive slip, extreme agitation of highly vis cous pulp, and hydraulic and mechanical shock; by reducing energy dissipation due to vibration; by eliminating excessive grinding by classifying the ore immediately after it is crushed; and by utilizing unavoidable turbulence and agitation to produce the jigging and flotation operation.

Still a further aim of primary importance in the invention is to provide a mill having ringshaped grinding dies, one of which is movable in a gyrating motion so that its engaging surface will roll on the grinding surface of the other, fixed die, and means for exerting pressure to force the movable die against the fixed die and which is arranged so that its center of gravity is above the center of the contact point of the movable die.

Still another aim of the invention is to provide a grinding mill wherein the gyratory motion of the movable die will produce hydraulic pressure for drawing the ore to be ground into a position between the engaging faces of the die, and for expelling the ground ore inwardly and into a jig bed and the pulp outwardly and into a classifying chamber.

Still another aim of the invention is to provide a mill having a gyrating shaft and die and which are so constructed that the gyratory motion of the shaft is utilized for pumping the pulp upwardly and into the flotation zone of the mill.

Other objects and advantages of the invention will hereinafter become more fully apparent from the following description of the drawings, which illustrate a preferred embodiment of the invention, and wherein:

Figure 1 is a side elevational view, partly in section of the grinding mill,

Figure 2 is an enlarged cross sectional view of the mill taken substantially along a plane as indicated by the line 2-2 of Figure 1,

Figure 3 is an enlarged central sectional view, partly in elevation of a portion of the lower part of the mill,

Figure 4 is an enlarged vertical sectional view, partly in side elevation showing the connection of the crank and gyratory shaft, and

Figure 5 is a diagrammatic view indicating the center of gravity of the force which is exerted on the movable die for holding it in position against the fixed die.

Referring more particularly to the drawings, wherein like reference characters designate like or corresponding parts throughout the different views, l0 designates generally a mill which includes a classifying and flotation tank, designated generally ll, having a restricted substan-, tially flat bottom l2 provided with a central opening l3.

A fixed, ring-shaped grinding die l4 rests on and is suitably secured to the bottom l2 and is provided with an opening l5 which registers with the opening I3. Die I4 is provided with a substantially flat upper, grinding surface I surrounded by an upwardly projecting flange ll. Above the tank II is disposed a suitably supported bearing I8 in which is journ aled a substantially perpendicular shaft 19. A pulley 20 is keyed to the upper end of the shaft l8 and a driven belt 2| is trained over the pulley 20 for revolving the shaft l9. Any suitable driving means, not shown, can be provided for actuating the belt 2|. As best seen in Figure 4, the shaft i9 is provided with a crank arm 22 at its lower end which projects laterally therefrom. A lever 23 is provided with a bifurcated portion 24 in which the crank arm 22 is disposed. The bifurcated portion 24 is connected at its free end to the free end of the crank arm 22 by means of a pivot pin 25. The opposite end of the lever 23 projects laterally from-the shaft IS, in the opposite direction to the arm 22, and said last mentioned end is provided with an opening which extends perpendicularly therethrough and which forms a bearing 26 which is eccent'rically disposed relatively to the axis of the shaft I9. It will thus be readily obvious that the lever 23 is mounted to swing in a vertical plane.

An elongated shaft 21 has a restricted stem 28 at its upper end which is journaled in the bearing 26. A head or plate 29 is mounted at the opposite, lower end of the shaft 21 and is reinforced by means of gussets 30, as best seen in Figures 2 and 3. A movable ring-shaped grinding die 3| is detachably secured to the under side of the head 28 in any suitable manner as by means of bolts 32. The opening 33 of the die 3| is disposed above the opening l5 and is closed at its top by the plate 29.

The under side of the die 3| forms its Erindinll face 34 which is adapted to engage the grinding face IS. The axis of the die H is substantially in alinement with the axis of the shaft l3 so that the axis of the shaft 21, as best seen in Figure 1, is disposed at an angle thereto. Consequently, the die 3| will be tilted, as best seen in Figure 3, so that only a portion of its face 34 will be in contact with the portion of the face it at any one time. The grinding face 34 is inclined outwardly and upwardly at an angle so that the contacting portion thereof will engage substantially flush against the portion of the grinding face it on which it rests.

A weight 35 is secured to th shaft 21 and equally disposed therearound. The weight 35 is disposed above and near the tank. ii and preferably comprises a container 35 having a removable cover 31 which is adapted to be filled with ore or other available material for weighting the shaft 21 to hold the contacting portion of the grinding face 34 flush against the portion of the grinding face it, on which it rests.

The tank includes a conical shaped lower portion 38 which forms the classifying zone thereof, and an annular upper portion 39 which forms the flotation zone thereof. A froth launder 43 is disposed around. and above the open top of the tank I The froth launder 4B is in the form of a trough, the inner wall of which is formed by the upper part of the tank I and the outer wall of which extends to a level above the top of the tank II. An inverted cone shaped member 4| is supported centrally of and in the upper part of the tank H by means of brackets 42 and extends substantially above thetop f the tank and terminates at its bottom slightly below the upper edge of the tank. A longer cone shaped member 43 is mounted in the tank I I in an inverted position and beneath the conical member 4| and is likewise supported by brackets 42, attached to the tank. The restricted upper end of the conical member 43 extends slightly into the enlarged lower end of the cone 4| from which it is spaced. The enlarged, lower end of the cone 43 terminates above the level of the upper die 3| and is spaced from the wall of the conical portion 38. The shaft 21 extends loosely through the cones 4| and Q3 and is adapted to gyrate therein.

A plurality of air pipes 44 extend into the tank H and open for discharge adjacent to the grinding surfaces of the dies I4 and 3| and beneath the cone 43. A tailings outlet 45 formed of extensible tube sections, projects upwardly and outwardly from the tank II and is adapted tov discharg into a trough or other suitable conduit 43. v

A funnel shaped member 4! is fastened to the bottom it beneath and around the opening I31 to form a jig chamber which is provided with a restricted passage 48 which extends from its restricted lower end and which forms a concentrate outlet. A screen 49 is disposed across the opening l3 and supports a plurality of pebbles in the openings I to form a jig bed 50 and a millwater conduit 5| extends upwardly through the jigbed 5|) and opens into the space formed by the opening 33. A jig water conduit 52 discharges into the jig chamber 41.

Referring to Figure 5, a circle A indicates the position of the center of the weight 35, when at rest, and the dotted line a. indicates its center of gravity. The circle B indicates the location of the center of the weight 35 when displaced by centrifugal force due to the gyratory motion of the shaft 21 and the dotted line indicated by b indicates the center of gravity thereof. The point C indicates the center of the contacting portion posed directly over the contacting portion of the I grinding faces so as to remove all gravity strain from the bearings 25, in one direction relatively thereto, and for removin centrifugal strain on said bearings, from the other direction, so that the bearings impart power input by circular motion only.

The ore to be ground is preferably fed through the top of cone 4| and descends downwardly on the'outer side of the cone 43, as indicated by the arrows 53, to be admitted to the portions of the engaging faces l6 and 34, which are out of contact. The gyratory motion of the die 3i causes it to roll in a circle on the grinding face it for grinding the ore between the contacting portions of the faces l5 and 34. The lever 23 allows the shaft 2i and the die 3| to move upwardly to ride over pieces of ore which it does not crush. Mill water is admitted to the tank ll through conduit 5|, as indicated by the arrows 54, and flows outwardly between the faces i5 and 3d and into the tank H to maintain a continuous supply of water thereto. The portion of the grinding face 34, moving out of contact with the face l5, creates a hydraulic suction which draws the particles of ore into position between the faces l6 and 34; the portion of the face 33 moving into engagement with the face it produces a hydraulic pressure which tends to force the comminuted ore inwardly and into the jig bed 53 while this pressure and the pressure of the Water from the conduit 5| forces the pulp outwardl and into the tank The air admitted through pipes 53 aerates the pulp and moves upwardly through the cone 43, as indicated by the dotted arrows 55. The gyratory movement of the shaft 2! in the cone 43 produces a pumping action for conveying'the air bubbles, carrying the pulp, upwardly and over the top of the cone 43 where the froth flows outwardly and into the froth launder 40. The water and tailings pass downwardly on the outer side of the cone 43 and the tailings are carried off through the conduit 45. Water is admitted through the jig water conduit 52, as indicated by the arrows 56, and is drawn upward ly through the jig bed 50 by the positive and negative pressures set up by the upward and downward movement of the die 3|, caused by it riding over the particles ofore which are not crushed. This likewise tends todraw in the heavier ground particles and force the underweight and undersize ore particles outwardly and also agitates the particles in the jig bed 55 to cause them to pass downwardly therethrough and through the concentrate outlet 58, from which the concentrates can beremoved. The rib or flange N forms a guide for the die 3| to keep it centered relatively to the die M.

The apparatus could also be used for dry grinding by enclosing the units in a suitable chamber so that by means of a vacuum fan the fine classified dust could be drawn out as produced. Also, the apparatus could be used for crushing intermediate sizeore to a smaller size for ball or mil] feed, with or without classification and either dry or in water.

The crushing unit can be used without the weight 35 by providing a suitable thrust bearing and heavy spring.

Various other modifications and changes are contemplated and may obviously be resorted to, provided they fall within the spirit and scope of the invention as hereinafter defined by the appended claims, as only a preferred embodiment of the invention has been disclosed.

I claim as my invention:

1. An ore grinding mill having coacting dies one of which is carried by a gyratory shaft, a rotatable driving element provided with a crank arm, a U-shaped lever in the bifurcation of which said crank arm is received so that the lever will turn with the element and crank arm, meansv pivoting each leg of the lever to the crankarm, said lever at an opposite end having an eccentric bearing opening, and said gyratory shaft having a portion extending into said eccentric bearing opening whereby the latter shaft will be gyrated through rotation of the lever and element.

2. An ore grinding mill comprising a fixed die, a gyratable shaft extending upwardly from above the center of said die, a movable die having a downwardly open central recess connected to the lower end of the shaft, a driven rotary shaft concentric with the fixed die, a crank pivotally connected to the rotary shaft, said first-mentioned shaft having its upper end journaled in the crank and eccentrically disposed relatively to the driven shaft for gyrating the movable die when the rotary shaft is revolved, said movable die engaging the upper surface of the fixed die, means extending through the fixed die and into the recess to supply fluid thereto, means for urging the movable die and shaft downwardly, said dies be ing ring-shaped, a liquid containing tank in the bottom of which said dies are disposed, and a jig bed located centrally of the fixed die, said tank being provided with an outlet beneath the Jig bed, the gyrating movement of the movable die relatively to the fixed die producing hydraulic currents adapted to concentrate heavy particles of ore, being ground by the dies, toward the Jig bed and expelling the underweight and undersized particles of the ore outwardly and into the liquid tank.

3. An ore grinding mill comprising a fixed die, a gyratable shaft extending upwardly from above the center of said die, a movable die having a downwardly open central recess connected to the lower end of the shaft, a driven rotary shaft con-,

centric with the fixed die. a crank pivotally connected to the rotary shaft, said first-mentioned shafthavins itsupperendjournaledinthecrank and eccentrically disposed relatively to the driven shaft for gyrating the movable die when the rotary shaft is revolved, said movable die engaging the upper surface of the fixed die, means ex- .tending through the fixe'd die and into the recess to supply fluid thereto, means for urging the movable die and shaft downwardly, said dies being ring-shaped, a liquid containing tank in the bottom of which said dies are disposed, a jig bed located centrally of the fixed die, said tank having an outlet below the jig bed forming a jig chamber, the particles of ore after being ground by the dies being adapted to be directed into the jig bed, said crank being arranged to permit upward and downward movement of the first-mentioned shaft and movable die to permit the movable die to ride over particles of are not crushed thereby. and said upward and downward movement of the movable die producing positive and negative pressures in the ig bed and jig chamber.

4. An ore grinding mill comprising a fixed die, a gyratable shaft extending upwardly from above the center of said die, a movable die having a downwardly open central recess connected to the lower end of the shaft, a driven rotary shaft concentric with the fixed die, a crank pivotally connected to the rotary shaft-said first-mentioned shaft having its upper end joumaled in the crank and eccentrically disposed relatively to the driven shaft for gyrating the movable die when the 1-0 tary shaft is revolved, said movable die engaging the upper surface of the fixed die, means extending through the fixed die and into the recess to supply fluid thereto, means for urging the movable die and shaft downwardly, said dies being ring-shaped, a classifying tank in the bottom of which said dies are disposed, means for sup- P 81118 9. liquid to the tank between the dies. said tank being provided with superposed inverted conical members through which the firstmentioned shaft extends, means for admitting air ,into the tank for directing pulp discharged from said first-mentioned shaft in the lower conical member functioning to pump the pulp upwardly andintothefiotationzoneofthetank.

FRANK J. RIVER-LAND.

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