US3140056A

US3140056A - Mill for the production of a directly floatable fluid pulp starting from coarse minerals

Info

Publication number: US3140056A
Application number: US120002A
Authority: US
Inventors: Motosi Aldo
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-06-17
Filing date: 1961-06-27
Publication date: 1964-07-07
Anticipated expiration: 1981-07-07
Also published as: FR1229109A

Description

3,140,056 BLE FLUID A. MOTOSI ION July 7, 1964 MILL. FOR THE PRODUCT OF A DIRECTLY FLOATA PULP STARTINGYFROM COARSE MINERALS Filed June 27, 1961 In venlor ALDO no'rosi AYM Attorneys United States Patent "ice 3,140,056 MllLL FOR THE PRODUCTION OF A DIRECTLY FLOATABLE FLUID PULP STARTING FROM CQARSE MINERALS Aldo Motosi, 13 Via dei Mille, La Spezia, Italy Filed June 27, 1961, Ser. No. 120,002 filaims priority, application Italy June 17, 1958 10 Claims. (Cl. 241-38) This application is a continuation in part of abandoned application Serial No. 820,015, filed June 12, 1959.

This invention relates to the comminution in water of solid coarse-sized minerals (this term including sizes up to 6" or even more) and aims to provide a mill in which the coarse minerals and the water are fed continuously and, at the same time, the minerals which have been comminuted to the desired degree of fineness are continuously discharged, together with the overflow water, in form of a directly floatable fluid pulp or slurry.

The object of the invention is to provide a mill which is very compact and efiicient and which permits of accurately regulating by simple means the size of the particles of the comminuted minerals.

According to the invention, these ends are attained by constructing a mill having a drum-like horizontal shell and a hollow rotor provided with radial openings, rotatably mounted therein, said shell being provided with a hopper'for the charging of the coarse mineral and with an ascending duct provided with an adjustable overflow and with valve means for regulating its sectional flow area, While the interior of the rotor is connected through rotary joints to a source of water and air under pressure which are discharged through said openings in form of radial jets which, during the revolution of the rotor, cooperate to entrain the bulk of water and minerals therein in form of a revolving liquid belt thrown away from the rotor by centrifugal force and spaced therefrom by a cushion of the air blown together with the water and which separates itself therefrom as soon as it may expand into the shell.

Due to the fact that the liquid belt is not entrained by blades dipping thereinto, the particles of water and solids assume diflierent annular speeds. Thus the said belt of turbulent water, by entraining solids of diiferent sizes and weight and having different velocities, causes said solids to collide and rub against each other and against the walls of the shell and to rebounce against the rotor therein from which they are hurled again into and through the liquid belt, until they are crushed by repeated collisions and rubbing to a suflicient fineness. When this sufficient fineness is attained, the particles of the mineral float into said swirling water until they reach a zone of quiet constituting the inlet end of an overflow duct from where they are discharged together with the water in which they are suspended.

Further characteristic features and advantages of the mill according to the invention will appear from the following specification in which the invention is described with reference to the attached drawings, in which:

FIGURE 1 is a vertical cross section through a mill according to the invention;

FIGURE 2 is a horizontal section taken on line IIII of FIGURE 1, and

FIGURES 3, 4 and 5 are cross sections through three modifications of the mill rotor.

According to one preferred embodiment shown in FIG- URES 1 and 2, the improved mill comprises a drum-like shell 11, supported by a base B, and provided with a hopper 13, through which the coarse-sized mineral to be ground is fed into the mill.

At one side of said hopper a duct 26-126 is formed,

3,148,855 Patented July 7, 1964 having an ascending branch 26 extending slightly above the nearest inner drum Wall and provided with a throttle valve 27 or equivalent means and a descending branch 126 connected to the ascending branch at a point below the hopper top and provided by its lower end with an outlet 29. In practice, the

ducts

26 and 126 may be formed by attaching to the hopper Wall a vertical partition 28 extending from underneath the inlet end of said duct 26, preferably above the level of the outlet 29. Said partition 28 is provided with a vertically movable extension constituted by a pair of parallel partitions 128 attached to a threaded stem 228 which may be axially shifted by means of a wing nut 328 rotatably but not axially shiftable mounted on a fixed part of the said hopper. Thus the

ducts

26 and 126 constitute a kind of adjustable overflow duct, the two branches of which are separated by a kind of sluice valve 28-128 the height of which determines the height of the liquid in the hopper 13.

Through two openings formed in the bottoms on the said drum 11 a shaft 15 is rotatably mounted.

In a central portion of said shaft, a tubular rotor 14 is mounted on a plurality of supporting members 16 fastened radially to the shaft 15. The rotor proper 14 is a tubular member provided with rows of radial perforations or slits 19 and preferably, but not necessarily, with very short projecting bars 18 extending longitudinally of the rotor, so as to remain well spaced from the drum interior.

The rotor 14 communicates axially with a pair of fluid feed chambers 25 fastened by their inner ends to the heads of the drum, the outer end of said chambers being provided with conventional wear sleeves 30 and stuffing boxes 32 in which the shaft 15 revolves with a fluidtight fit. The chambers 25 are provided with valved ports or nipples 31 and 131 through which the fluids (water, chemicals, if any, and air) which are necessary for performing the process of the invention are fed. In the example as shown, air may be fed with suitable pressure through the port 131. The mill shell is usually provided with the conventional liner, which, in the examples as shown is in the form of spaced bars 23.

The operation of the mill is as follows: The mill is first run by feeding therein, through the rotor 14, some water which is sprayed through the slits 19 into the drum 11 until its level rises into said drum substantially at its overflow level. Together with the water (which may contain some chemicals, if required) also some air may be fed, in order to create an air-filled space at the central portion of the mill, inside an annular belt of water thrown by centrifugal force away from the rotor 14. Then the coarse material to be ground finely is fed into the hopper 13 and allowed to fall in the direction of the rotor 14 which throws by centrifugal force both solids and the liquid coming into contact therewith towards and through the annular belt of water, where they encounter other fragments of solid materials and finally the shell walls or liner. At the same time, the jets of water projected with great force through the openings or slits 19 and revolving with the rotor, by acting upon the inner surface of the belt of water, entrain said water and the solids therein into rotation, but at different velocities. Thus a combination of repeated rubbing and impact of the materials between them and against the mill and rotor walls takes place inside the mill, in which the coarse solid material is reduced to the required fineness.

The operation of this mill is a continuous one, that is the solid material to be ground is fed at a rate determined by experiments and at the same time water and some air are fed into the mill across the rotor openings and at the same time the water charged with ground material of the required fineness or pulp flows upwardly through the ascending branch of duct 26, overflows the partition 128 and flows down through the descending duct 126 until it is discharged through the outlet 29. The pulp may be fed directly to a flotation equipment-for separation of its valuable parts from the gangue.

The fineness of thepulp may be exactly regulated by suitably adjusting the rate of feed of the liquid, the height of the

overflow

28, 128 and the free passage area of the ascending branch of duct 26. In fact, by leaving all other conditions unaltered, it is evident that the fineness of the ground material entrainedby the overflow water will be inversely proportional to the velocity of the ascending water flow in the duct 26 and thus by throttling more or less the, ascending branch 26 of this duct by means of valve 27, FIG. 1, the fineness of the discharged fluid pulp may be exactly regulated.

As said in the preamble, experience has shown that, in order that mill may operate ,as described, the belt of water should not be entrained into rotation by long bladelike members projecting out of the rotor surface radially thereinto. Onthe contrary the projecting parts of the rotor-if anyshould be well spaced from the drum interior as to come to be almost always inside of the inner surface of the water belt.

Although in FIGURE 1 the rotor 14 is shown provided with projecting bars 18, these bars may be completely omitted or replaced by channels 118 (FIGURE 3) grooves, flutings and even-a roughened surface.

In FIGURE 4, as variation, there is shown, a cylindrical rotor 14 mounted eccentrically on its shaft 15.

In FIGURE 5, the rotor 214 is elliptical.

In any case, it is to be understood that the most projecting parts of the rotor must be such that their distance from the nearest part of the drum interior is less than the size of the coarsest material to be fed into the mill.

Furthermore the rotor 14 is usually mounted in the drum eccentrically, as in the case as shown, in which the drum shell 11 is substantially spiral-shaped.

All the above and other possible embodiments of the invention should be such as to promote the formation of a water belt, containing the solids to be comminuted in it and spaced, at least in part, from the rotor, by an air cushion, the whole in order to avoid that the liquid and solid parts forming the belt revolve at substantially the same angular speed or conversely in order to cause the solids in the belt to revolve at different angular speeds, according to their different weights and position in the liquid belt, thus tending to impact or rub-against each other and the drum walls, or the lining bars thereof.

I claim:

1. A mill for the continuous production of a directly floatable fluid pulp starting from coarse-sized solid materials, comprising adrum-like shell, a feed hopper for solid materials opening into the extending above said shell, a hollow rotor journaled for rotation within said shell and having a peripheral surface spaced from the shell, radial through-openings in the peripheral surface of said rotor communicating with the hollow interior thereof, means for feeding aqueous fluids into said hollow rotor and through said radial openings into said shell, means for rotating said rotor at high angular speed, and an ascending overflow duct opening into and extending above said shell.

2. A mill according to claim 1, in which the rotor is provided with short parts projecting from its peripheral surface and which are spaced from the shell interior by more than the maximum size of the material to be comminuted.

3. A mill according to claim 1, in which the rotor is provided with longitudinalgrooves.

:4. A mill according to claim 1, in which the rotor is elliptical in cross section.

5. A mill according to claim 1, comprising means for adjusting the height of the overflow duct.

6. A mill according to claim 1 wherein is additionally provided duct means for collecting and discharging the fluid overflowing from said overflow duct.

7. A mill according to claim 1 in which the rotor is jurnaled for rotation about a horizontal axis eccentrically positioned with respect to said shell, the peripheral surface of said rotor being spaced at all points from the shell by a distance that is greater than the maximum size diameter of the material to be comminuted.

8. A mill according to claim 1 wherein said radial through-openings have small diameters sutficient only to pass aqueous fluids but too small to pass the solid material to be comminuted.

9. A mill for the continuous production of a directly floatable fluid pulp starting from coarse-sized solid materials, comprising a drum-like shell, a feed hopper for solid materials opening into and extending above said shell, a hollow rotor journaled for rotation within said shell and having a peripheral surface spaced from the shell, radial through-openings in the peripheral surface of said rotor communicating with the hollow interior thereof, means for feeding aqueous fluids into said hollow rotor and through said radial openings into said shell, means'for rotating said rotor at high angular speed, and an ascending overflow duct opening into said shell, said overflow duct comprising an upright, partition wall within the hopper extending downwardly to a level slightly within the confines of the shell, a second upright wall within the hopper substantially parallel to said first wall and extending upwardly from a level in the lower part of said hopper, a sluice valve-like member coacting with the top part of said second upright wall to extend it upwardly, said sluice member having a top edge which constitutesthe top of said overflow duct, and means for shifting said sluice valve member vertically so as to lift and lower its top edge, said hopper having an opening in its side opposite said second partition wall for discharging fluid overflowing from said overflow duct.

10. A mill according to claim 9 in which valve means are provided in the said overflow duct for constricting its free flow area.

UNITED STATES PATENTS References Cited in the file of this patent 1,780,845 Sherwood Nov. 4, 1930 2,656,119 Shelton et al. Oct. 20, 1953 2,914,259 Hestvik et a1. Nov. 24, 1959 3,030,037 Raetz Apr. 17, 1962 3,038,669 Lykken et al. June 12, 1962 FOREIGN PATENTS 581,986 Canada Aug. 25, 1959

Claims

1. A MILL FOR THE CONTINUOUS PRODUCTION OF A DIRECTLY FLOATABLE FLUID PULP STARTING FROM COARSE-SIZED SOLID MATERIALS, COMPRISING A DRUM-LIKE SHELL, A FEED HOPPER FOR SOLID MATERIALS OPENING INTO THE EXTENDING ABOVE SAID SHELL, A HOLLOW ROTOR JOURNALED FOR ROTATION WITHIN SAID SHELL AND HAVING A PERIPHERAL SURFACE SPACED FROM THE SHELL, RADIAL THROUGH-OPENINGS IN THE PERIPHERAL SURFACE OF SAID ROTOR COMMUNICATING WITH THE HOLLOW INTERIOR THEREOF, MEANS FOR FEEDING AQUEOUS FLUIDS INTO SAID HOLLOW ROTOR AND THROUGH SAID RADIAL OPENINGS INTO SAID SHELL, MEANS FOR ROTATING SAID ROTOR AT HIGH ANGULAR SPEED, AND AN ASCENDING OVERFLOW DUCT OPENING INTO AND EXTENDING ABOVE SAID SHELL.