US2208077A - Grinding mill - Google Patents

Description

G. LINKE GRINDING MILL Filed Oct. 14, 19:57

July 16, 1940.

lnven for:

Gerhard Linke IIIIIIIIIIIIIIIIIIII Attorney Patented July 16, 1940 UNITED STATES PATENT FFiCE GRINDING NULL Application October 14,

1937, Serial No. 168,865

In Germany October 15, 1936 4 Claims.

My invention relates to continuously acting mills for crushing and grinding materials in bulk such as lumps or granules of minerals, ore, coal, rock, crystalline chemicals, cement clinkers, etc.,

5 Which are continuously fed into and continuously delivered from the mill in pulverized condition.

The invention relates more especially to improvements in continuously acting crushing and l grinding mills of the gyrating type having a plurality of material receiving containers which are bodily gyrated at high frequency, namely moved in closed cycles of movement of relatively small diameter in contradistinction to the rotary motion of conventional drum and ball mills, tube mills and other mills of the rotary type.

A continuously acting grinding mill of the gyrating type is known in the art from United States Patent No. 2,117,965, and comprises a plurality of grinding chambers having a flat bottom and dat Walls which are transversely arranged side by side and enclosed in a rectangular box frame and are alternately connected in pairs at their ends for intercommunication so that the material agitated in the said chambers and gravitationally forced ahead by the load of the fresh material continuously fed thereinto Will migrate from chamber to chamber in a zig-Zag path of movements, namely transversely through the grinding mill described.

The primary object of this invention is to provide a gyrating grinding mill of improved design distinguished by its high grinding eiciency and large output combined with relatively small consumption of power and low temperature up to which the material is heated during the treatment.

In connection therewith the invention aims at providing a multiple chamber grinding mill, that 40 can be used to advantage also for Wet grinding in as much as its eiciency and grinding capacity is not affected by Water or another liquid contained in the grinding chambers, as against rotary ball and rod mills of known design, Wherein the presence of water in the mill generally reduces the frictional contact of the grinding elements and the inner Walls of the mill and thereby impairs the trundling motion and grinding action of the grinding elements concerned.

Other objects aimed at and advantages obtained by the invention will become incidentally apparent to practitioners in this field as the description proceeds.

The nature and scope of this invention are briefly outlinedv in the appended claims and will be more fully understood from the following specication taken together with the accompanying drawing, in which Fig. 1 is a partly fragmentary longitudinal section vertically taken through a multiple chamber rod mill designed according to this invention and shown by Way of an example;

Fig. 2 is a plan partly in section of the mill shown in Fig. 1;

Figs. 3 to 5 are longitudinal sections vertically taken through structurally modified grinding chambers of grinding mills designed according to this invention;

Figs. 6 and '7 are fragmentary cross sections drawnI in a larger scale and taken vertically through one of the grinding chambers of the mill shown in Fig. 5.

Briefly stated, the vital parts, of which the grinding mill designed according to this invention is composed, comprise a mill housing, a plurality of grinding chambers having one-dimensionally curved inner Working faces and being transversely arranged side by side in said housing so as to communicate with each other at their upper ends, means for bodily gyrating said chambers in vvertically disposed cycles of movement substantially coinciding with the vertical plane of symmetry longitudinally intersecting the mill, and means for feeding the material into and discharging it from the mill.

One of the most salient features of the invention consists in that the gyrating motions are imparted to the mill in clockwise direction when looking at the mill from what may be appropriately called its right side, as indicated by arrow a as in Fig. 1.

Because of the specic nature and direction of the gyrating motions the material under treatment Will-o-n being agitated, preferably jointly with grinding elements-revolvingly move in circular paths of movements interlooping each other, as indicated at x-m in Fig. 1, and will incidentally ascend on the curved Working faces of the grinding chambers and eventually climb over their front edges, as indicated by arrow :12", so as to dynamically as against gravitationally migrate from chamber to chamber and in longitudinal direction through the mill.

In the embodiment of the invention shown by way of an example in Figs. 1 and 2 the improved grinding mill comprises:

(1) A foundation or bed plate 30;

(2) A mill housing in the form of a rectangular box frame 40, closed at the top by a lid 42 and yieldingly supported on said bed plate by means of coil springs 33, 33', 34, 34 for being gyrated;

(3) A plurality of trough shaped material receiving elements 50, 5l, 52, 53, transversely arranged in said box frame immediately adjacent to one another and so as to subdivide the interior of the boX frame 40 into a series of grinding chambers having one-dimensionally curved surfaces, that is the inner contour being straight lengthwise and the cross-sectional inner contour being the same at all points along the length; said plurality of troughs communicating with each other at their upper partitional walls in which are located sieves 5B, 6|, S2, 63 graduated as to the size of their meshes, namely, having meshes of progressively smaller size in the direction of ow of the material are provided;

(4) Grinding elements, preferably rods 5, of approximately the same length as the troughs, which are loosely assembled therein and so proportioned as to their diameter, that, while the troughs are gyrated in clockwise direction as indicated by arrow a and at a number of periods preferably exceeding 500 per minute, the grinding rods are violently revolved in anticlockwise direction by the impetus Pt received at the end of the ascending motion of the troughs, as seen in Fig. 6

(5) Means for gyrating said troughs which comprises a transverse rotary shaft 1 journalled i-n the box frame 4l) at points corresponding with the center of gravity of the mill, ily wheels keyed to shaft 1 and having unbalance weights 2, 2' attached, and a pulley 3 for rotating the shaft in clockwise direction;

(6) Feeding means comprising a hopper 9 and a iiexible hose I enclosing the latter and sealing the intake 1 from the outer atmosphere so as to prevent the escapement of dust therefrom;

(7) A chute 8 for discharging the comminuted material, which passes out of trough 53 through sieve 63;

(8) Dust collecting means which comprise a rotary suction fan IB, a dust collector I1 both of conventional design and a system of pipe lines by which the said fan and dust collector are interconnected in series with the grinding cham-v bers; said system of pipe lines includes a main pipe I2, I2' having branches I3, i3', I3 in communication with the interior of the grinding chambers 52, 53, a return pipe l2 connecting the dust collector 1 with the grinding chamber 59 at the feed end of the mill and flexible ducts I4, I4' allowing of gyration of the mill.

Various changes and modifications may be conveniently made in the structural details and assemblage of the component parts of grinding mills of the improved design shown and described with reference to Figs. 1 and 2, without substantially departing from the spirit and the salient ideas of this invention.

In Fig. 3 a structurally modied gyratory grinding mill having the features of this invention is diagrammatically shown. by way of another example, of which the troughs or gri-nding chambers 10, 1|, 12, 13, 14 and the grinding elements 5a, 5b, 5c, 5d, 5e contained therein are graduated as to their capacity and diameter respectively-namely being progressively reduced step by step in the direction of flow of the material, which is fed at 15 into the mill and discharged through delivery chute 8a; in contradistinction to the specic inclined arrangement of the troughs 50, 5|, 52, 53 seen in Fig. 1, of which the sieves 60, 6|, 62, 63 are rearwardly inclined towards the feed end of the mill. The sieves 1a, 1b, 1c, 1d, 1e interconnecting the individual troughs 10, 1|, 12, 13, 14 in Fig. 3 are inclined towards the delivery end of the mill in order to facilitate the flow of the ground material from one trough to the next one.

In another structurally modied grinding mill shown in Fig. 4 the troughs 80, 8|, 82, 83 are of semicircular cross sectional shape and are perforated with the object of allowing fines to be separated, for instance fines of softer material such as slag encrusted to pieces of lumped iron, which are not to be materially comminuted or at least not to be completely disintegrated; said nes are discharged through the lower chute 8b, while the other material under treatment is delivered at the upper chute 8c.

Instead of providing the grinding mill with troughs of the design shown in Figs. 1 to 4 the mill may be made to advantage of a rectangular box frame 44 closed at its top by a lid 45, and at its bottom by a bottom plate 46, and of a plurality of partition walls 41 perforated at 41', by which the interior of the box frame is subdivided in a structurally simpler way into a series of grinding chambers 90, 9|, 92, 93 having a flat bottom and concave front walls, as seen in Fig. 45.

Grinding mills of this design are particularly adapted for wet grinding, if provided with a relatively thick lining i of elastic material such as india rubber or a rubber substitute capable of replacement, as seen in Figs 5, 6 and 7: Whereas in grinding mills of the conventional rotary drum and ball or rod type the frictional interengagement of the rounded grinding elements and the inner Working face of the drum is generally greatly reduced in the presence of water or another liquid. which acts as a lubricant, frequently to an extent that the rolling and trundling motion of the grinding elements, and in consequence their grinding action, is completely impaired.

The said drawback is eliminated according to this invention:

As seen in Fig. 6 the grinding rods 5i resting on the lining z' by their own inertia P will indent into the lining i each time that the mill ascends during its gyratory motions and will receive a revolving impetus Pt like the intermeshing teeth of a toothed gearing.

By appropriately proportioning the-thickness of the elastic' lining i consistent with the yielding and buoyant properties of the material from which it is made, a highly ecient frictional interengagement of the grinding members and the gyrating working faces of the grinding mill is obtained and its grinding power restored notwithstanding the lubricating action of water present in the mill.

The said elastic lining may be conveniently formed with a corrugated or undulated face as indicated at i' in Fig. 7; in this case a harder and less elastic lining more resistive to wear may be employed to advantage.

In cases". where the material in bulk under treatment consists of components of different hardness, for example, of lumps of iron as obtained by the lumping process disclosed in United States Patent 1,964,917, and of slags adhering to said lumps of iron, grinding balls, rods or other additional grinding elements may be dispensed with to advantage because of the harder components of the material taking over the grinding work and abrading the softer substances, which are preferably concurrently separated in mills having troughs with a perforated bottom as shown in Fig. 4.

Practical tests carried out with mills of the improved design described have shown that on using rounded grinding elements, the latter will, as the result of the impetus Pt received, ascend at the front walls of the grinding chambers, as seen best in Fig. 5, and then rollingly drop down into the lower sections of the grinding chambers, while the material migrates therethrough in interlooping paths of movement indicated by arrows r', in Fig. 1.

Good results have been obtained with gyrating grinding mills of the design described having a frequency of 500 to 800 periods per minute and an amplitude or diameter of their gyratory displacement of 4 to 6 mm., as indicated at d in Fig. 6.

What I claim is:

1. A mill for continuously grinding material in bulk, comprising a horizontally disposed, troughshaped grinding chamber closed by walls at the top and both ends, and having its sides comprising a wall formed with a concave, onedimensionally curved face which serves as an impeller for the materials to be treated within the chamber, said chamber having in its upper portion an intake port and a screened outlet port. the latter being arranged Within the said Wall of said chamber and constituting a screenlike continuation of its concave impeller face, and means for gyratng said chamber transversely to its axis and in clockwise direction of rotation when viewed from the end and the intake port is on the left and the outlet port on the right.

2. A mill for continuously grinding material in bulk, comprising a horizontally disposed, troughshaped grinding chamber closed by Walls at the top and both ends, and having its sides comprising a Wall formed with a concave, one-dimensionally curved face which serves as an impeller for the materials to be treated within the chamber, said chamber having in its upper portion an intake port and a screened outlet port, the latter being arranged within the said wall of said chamber and constituting a screenlike continuation of its concave impeller face, means for gyrating said chamber transversely to its axis and in clockwise direction of rotation when viewed from the end and the intake port is on the left and the outlet port on the right, and an elastic cushion, lining the said concave working face of the grinding chamber.

3. A mill for continuously grinding material in bulk comprising a plurality of horizontally disposed trough-shaped grinding chambers arranged adjacently to each other side by side, each chamber being closed by walls at the top and both ends and having its sides comprising a concave wall formed with a concave one-dimensionally curved inner face, which serves as an impeller for the material to be treated within the chamber, the initial receiving chamber of said plurality of chambers having an intake port in its upper portion and each of said chambers having a screened outlet port, the latter being arranged within the side wall of said chamber and constituting a screenlike continuation of said concave impeller face, and means for bodily gyrating said chambers transversely to their axis and in clockwise direction of rotation when viewed from the end and the intake port is on the left and the outlet port on the right.

4. A mill for continuously grinding material in bulk, comprising a horizontally disposed, troughshaped grinding chamber closed by walls at the top and both ends, and having its sides comprising a wall formed with a concave, one-dimensionally curved face which serves as an impeller for the materials to be treated within the chamber, said chamber having in its upper portion an intake port and a screened outlet port, the latter being arranged within the said wall of said chamber and constituting a screenlike continuation of its concave impeller face, means for gyrating said chamber transversely to its axis and in clockwise direction of rotation when viewed from the end and the intake port is on the left and the outlet port on the right, and grinding elements loosely assembled in said chamber and comprising a plurality of rods extending longitudinally within said chamber.

GERHARD LINKE.

Images