US686621A - Tubular ball-mill. - Google Patents

Description

Patented'Nov. [2, I905; P. T. LINDHARD.

TUBULAR BALL MILL. I

(Application filed Dec. 28, 1900.)

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ATTORNEYS.

P. T. LINDHABD.

TUBULAR BALL MILL.

(Application filed Dec. 98, 1900.)

(No Model.)

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ATTYS screened center outlet, at approximately the UNITED STATES POVL T. LIN DHARD, OF RICHMOND HILL, NEW YORK, ASSIGNOR TO F. L.

PATENT OFFI E.

SMIDTH & COMPANY, OF NEW YORK, N. Y., CORPORATION.

TUBULAR BALL-MILL.

SPECIFICATION forming-part of Letters Patent No. 686,621, dated November 12, 1901.

Application filed December 28, 1900. Serial No. 41,331. (No model.)

To a. whom it may concern.-

Be it known that I, PovL' T. LINDHARD, a citizen of the Kingdom of Denmark, residing in Richmond Hill, in thevcity of New York, borough of Queens, inthe State of New York, have invented certain new and useful Improvements in Tubular Ball-Mills, of which the following is a specification.

This invention relates to improvements in tubular ball-mills, and more especially to mills designed for grinding material in a semiliquid or pasty condition-such, for instance, as that known in the cement industry as slurry. In a dry mill, or one designed for grinding material in a dry state, good results are obtained when the dischargeopenings are arranged near the circumference of the discharge-head; but this construction is not adapted for a wet mill, because when the mill is stopped a quantity of the unground or. partly-ground material, termed grit, will drain outwith the prop erly-ground product. Neither is a plain same level as the inlet, suitable, though overcoming this disadvantage, because the econ-' omy of the mill depends upon the gradual and progressive distribution of the material among the balls, and this is not easily obtainable with such an outlet. There was with such an outlet danger of over-filling the mill, while circumferential openings possessed the contary disadvantage that it was not possible to work the mill to its full capacity owing to the greater fluidity of wet as compared to dry material.

The object of this invention is to provide means for overcoming these objections; and for this purpose the invention consists in the combination in a tubular ball-mill,with a grinding-drum having an inlet, of a screenplate in said drum having perforations below the level of the inlet, grinding-balls in the drum, and a dischargecone embracing said perforations within its base, said cone rising-between the base and apex above the level of the lowermost perforations.

The invention consists, further, in certain other combinations of parts more fully described hereinafter and claimed.

In the accompanying drawings, Figure 1 is a side elevation of my improved mill. Fig. 2 is a section on line 2 2, Fig. 1, with the perforated portion of the screen-plate removed. Fig. 3 is avertical section on line 3 3, Fig. 2, with the perforated portion of the screen-plate in place; and Fig. 4 is a vertical central section through the mill, showing the relative heights of the inlet and outlet and the openings in'the screen-plate.

Similar letters of'refere'nce indicate corresponding parts.

Referring to the drawings, A indicates the drum orjtube of a tubular ball-mill of any approved construction and provided at the interior with grinding-balls in the usual manner. The drum is provided with an inlet-head B,havinga tubular shaft or gudgeon b,serving as the inlet,which communicates with a feed-pipe B, through which the material to be ground is fed. The outgoing head G of the mill is at tached to the drum by bolts (1' or otherwise and is provided with a tubular shaft or gudgeon c,preferably tapering outwardly at its interior and serving as the outlet of the drum to which is connected the discharge-pipe ct.

At the outgoing end of the drum is arranged a screen- .plate D E,preferably made with its perforated portion E detachable from the closed portion D; but it may be made in one or any desired number of pieces and secured either to the drum or to the outgoing head 0, as shown by bolts c,or in any other suitable manner. The lowermost perforations-4. a, those at the greatest radiusfrom the axis of the millare located below the level of the inlet, and the level of the outlet is above the level of said perforations, as shown in Fig. 4.

Between the screen-plate and the outlet of the mill, in line with the outlet, is located a discharge-cone F, which communicates at its apex with the outlet and at its base with said perforations. In said cone are arranged conveyer-blades G, which serve as'means for conveying the ground material through the cone. The cone may be attached to the screen-plate by bolts f engaging the flange f of the cone and to the head 0 by bolts f engaging flange f of the cone or in any other suitable manner. When the cone is attached to the mill so as to rotate therewith,the motive power of the latter serves through the mill as means for rotating theconeandconveyer-blades. The conveyorblades may be positively secured in the cone in any suitable manner; but they will ordinarily have some spring tension and in this case will retain their position therein by friction with the same, so as to rotate with the cone without slip.

The necessary gradual distribution of the material among the balls is secured by my improved construction by reason of the fact that the material is discharged through the screenplate at a lower level than that at which it enters the drum. \Vhen the mill is stopped, no material will flow out of the same; butin leveling itself in the mill a small portion of the material nearest the cone will enter the cone and when the mill is again started will be conveyed out of the same; but as this portion has been almost completely ground and owing to the fact that the cone tapers from the perforations to the outlet is small in quantity it does not materially affect the uniform character of the product. The conveyer-blades are made of greater width at their outer ends adjacent to the screen-plate than at their inner ends, as shown in'Fig. 4, and of sufficient height so that they serve to block the entrance of the material into the cone when leveling itself in the mill after stopping the same. The thicker the material to be ground the nearer to the circumference of the screen-plate can the perforations of the same be made, and by inserting different cones and regulating the size and number of holes in the screen-plate the mill can be made to grind a material containing any given amount of moisture with the highest economy.

Having thus described my invention, I laim as new and desire to secure by Letters Patent- 1. In a tubular ballmill, the combination, with a grinding-drum having an inlet, of a screen-plate in said drum having perforations below the level of the inlet, grinding-balls in the drum, and a discharge-cone communicating with the outlet and embracing said perforations within its base, said cone rising between its base and apex above the level of the lowermost of said perforations, substantially as set forth.

2. In a tubular ball-mill, the combination, with a grinding-drum having an inlet, of a screen-plate in said drum having perforations below the level of the inlet, grinding-balls in the drum, and a discharge-cone communicating with the outlet and embracing said perforations within its base, said cone rising between its base and apex above the level of the lowermost of said perforations, and means forconveying material through said cone, substantially as set forth.

3. In a tubular ball-mill, the combination, with a grinding-drum having an inlet, of a screen-plate in said drum having perforations below the level of the inlet, grinding-balls in the drum, a discharge-cone communicating with the outlet and embracing said perforations within its base, said cone rising between its base and apex above the level of the lowermost of said perforations, and conveyorblades in said cone, substantially as set forth.

4. In a tubular ball-mill, the combination, with a grinding-drum having an inlet, of a screen-platein said drum having perforations below the level of the inlet, grinding-balls in the drum, a discharge-cone communicating with the outlet and embracing said perforations within its base, said cone rising between its base and apex above the lowermost of said perforations, conveyer-blades in said cone, said blades being at their inner ends adjacent to the screen-plate of suflicient width to block the entrance of material into the cone when the mill is stopped, substantially as set forth.

5. In a tubular ball-mill, the combination, with a grinding-drum having an inlet, of a screen-plate in said drum having perforations below the level of the inlet, grinding-balls in the drum, a discharge-cone communicating with the outlet and embracing said perforations within its base, and conveyor-blades in said cone, and abutting at their inner ends against said screen-plate, substantially as set forth.

6. In a tubular ball-mill, the combination, with a grinding-drum having an inlet, of a screen-plate in said drum having perforations below the level of the inlet, grinding-balls in the drum, a discharge-cone communicating with the outlet and embracing said perforations within its base, and conveyer-blades in said cone, said conveyer-blades having spring tension and frictionally engaging the sides of the cone, substantially as set forth.

In testimony that I claim the foregoing as my invention 1 have signed my name in presence of two subscribing witnesses.

POVL T. LINDHARD.

Witnesses:

PAUL GOEPEL, GEORGE E. GEIBEL.

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