US2217300A - swart - Google Patents

Description

Oct 8. 1940. R. E. TEMPLETON 2,217,300

HOLE DIGGING MACHINE Filed Feb. 25, 1940 INVENTOR ATTORNEYS UNITED STATES PATENT OFFICE.

WALTER G.- SWAR'I, FRED JORDAN, EDWARD w. DAVIS, AND THEODORE B.

, COUNSELMAN, 0F DULUTH, MINNESOTA.

rRocEs's ron THE MAGNETIC srzmc AND GRADING or can.

Specification of Letters.Patent. 5 Patented May 4 1920.

Application filed September 11, 1917. Serial No. 190,718.

To all whom it may concern:

Be it known that we, WALTERG. SWART, FRED A. JORDAN, EDWARD W. DAVIS, and

THEODORE B. COUNSELMAN, citizens of the.

Sizing and Grading of Ore, of which the I following is a specification.

This invention relates to improvements in processes for the magnetic sizing and-grading of ore, and has for its object to provide a process of that nature by which we may substantially dispense with the use of belt and bucket elevators and similar devices, and also with the use of screens. In present day processes for magnetic separation and concentration of oresv bucket elevators are generally used, and also sizing andgrading screens, both of which elements are subject to great wear and require frequent replacing, resulting in the shutting down of the mills, considerable'ex ense incident to such shutting down, and the replacement of the worn out apparatus. By the employment of our process we are enabled to dispense very generally with such elevators and screens, and more efliciently and economically to concentrate and size the ore by the use of magnetic cobbers and other apparatus, as

will be more fully hereinafter explained,

and by the use of the apparatus shown in the accompanying drawings, in which-- Figure 1 is a perspective view of one cobber set.

Fig. 2 is a side elevation of the same.

Fig. 3 is a diagrammatic view of a wiring arrangement to permit variation of the intensity of themagnets of one cobber,--the first three views being more or less diagrammatic in their nature.

Fig. 4 is a diagrammatic flow sheet, show ing one arrangement of multi-stage apparatus.

Fig. 5 is a similar view of another arrangement; and v Fig. 6 is a similar view of still another arrangement. I

Like numerals refer to like elements throughout the drawings.

Hithertoseparation of magnetically susceptible ore has been effected by the use of magnetic cobbers in the-separation and concentration of iron ore, such as magnetite, which is susceptible of such magnetic separation, but to the best of our knowledge such separation has been crude, and cobbers have never been used for grading both as to size and magnetic susceptibility simultaneously, as in the case with our process and apparatus.

In the present day and prior processes the magnetic separation has been purely a separation with regard to the iron or other magnetically susceptible ore content, regardless of size, the limit of effect of such processes being to cause only such a separation, and in no way to effect a grading as to the size of particles of low grade, or such as would be classed as tailings- By our process we are enabled to use as a by-product the tailing particles where the same are sized, there being a demand for two sizes especially, one comparatively large and usable as railroad ballast, and the other of lesser size and usable and in demand as road material. The

carrying out of our process enables us to effect the sizing of these tailing particles so that they are ready for immediate use without further crushing or sizing.

In Fig. 1 is shown a perspective view of one cobber set, this view, as is the case with Figs. 2 and 3, being partially diagrammatic in character. In this view 10 designates a pulley or drum rotating with a shaft 11. 12 designates a driving belt operating to drive the belt pulley 13 carried upon thehollow sleeve or shaft 14:, which is rigidly attached to the cobber drum 15, and which rotates upon the hollow fixed shaft 16. A belt 17 preferably of resilient material, such as rubber or the like, passes around the cobber drum 15 and the drum 10, and terminating adjacent the upper face thereof is a chute 18, intended to supply crushed ore to the surface of the belt 17 and thence thereon.

'ing to suitable bins, conveyers, or the like,

as may be desired. Located within the cob- I ber drum 15 are the magnets 20, illustrated diagrammatically in Fig. 2 and shown more in detail in Fig. 3, where a stationary magnet yoke 20 is provided, from which pro- 'ect outwardly or radially the magnets 20 aving pole faces 20 at their outer ends adjacent the inner periphery of the drum 15. In the diagram shown in Fig. 3 a common feed wire 21 is electrically connected to each of the magnet coils, the other terminals of the latter leading to suitable rheostat or current-regulating devices 22 which are in communication with a second feed wire 22 the purpose of this construction being to enable us to regulate the magnetic intensity of each magnet, as will be obvious, by var ing the current flow in the embodiment s own. I 4

In the construction and arrangement of apparatus shown it is to be noted that the first of the magnets in the direction of the belt travel is located adjacent the first contact of the belt with the drum or pulley,

for a purposeto be hereinafter described. In the operation of a single unit, such as shown in Figs. 1 to 3, which is typical of our apparatus, crushed ore is fed along the chute 18 upon the surface of the belt 17, upon which it travels toward the cobber drum 15.- Each particle of crushed ore as it reaches the cobber drum-assuming the magnets to be electrically-excitedvis subject to a number of forces, the most important of which are momentum due to the inertia-of the particles and the velocity of thebelt, gravity, and magnetic attraction. The force of gravity, of course, is constant, and, assuming the magnets to be unexcited, each particle will be projected outwardly fromthe cobber drum in a substantially parabolic path if the resistance of the air is disregarded, the distance of outward projection in the case of any particle varying according to the speed of the belt. With the magnets excited, however, and at a given belt speed, the path traveled by the particles will depend upon the magnetic attraction exerted upon the particles by the magnets. Relatively large particles, not magnetically susceptible, will not be affected by the magnetic attraction, and but inappreciably affected by the resistance of the air, and will closely approximate in their path or trajectory a parabola, and will be projected farthest from the cobber. Small particles of high magnetic susceptibility will be carried around the drum until free from magnetic attraction, then will drop, for example, in the space or bin Z. In between these two extremes are a number of other particles of varying size and magnetic susceptibility, which will be affected differently. For example, finely ground particles or dust, known as fines inthe art, will be affected by the resistance of the air, or will be caged or held on the drum bythe attracted ore particles until the greater part will either fall in space Y with what are known as the middlings, or

in space Z with theconcentrates, even though the magnetic susceptibility be low. Large particles of fairly high grade will be affected more strongly by the centrifugal force of the cobber or velocity of the belt vthan small high grade particles, and, owing as by providing different sized magnets,

greater current supply, or the like the separation into three grades may be so effected that all particles falling into space X will be of large size and of practically no magnetic susceptibility, and may be con- Sidered as tailings; and in space Z are deposited very small particles of high grade mixed with some attached dust particles of low grade, and sometimes larger high grade particles, whose collection with small high grade particles is not deleterious to the carrying out of the process. In space Y will be deposited substantially all particles not to be classified with the large tailings or the high grade concentrate, and which it is desirable in many instances to re-treat and re-crush. Particles in X, if so desired, may be subjected to a further treatment by-crushing and separation, but enerally it will be found desirable to consi er them solely as tailings and worthless except for railroad ballast purposes, or the, like. The particles falling in space Z will be of high grade and finely comminuted or pulverized, and will require no further preliminary crushing and be of such size as to be taken directly to the ball mill for final grinding preliminary to the final concentration. The particles deposited in space 'Y will be either subjected to a second separation or conveyed to crushing rolls,-'whi.ch will further crush them to a smaller mesh, after which the operation may be repeated, either to efi'ect athree-class separation as just described, or a two-class separation, as found desirable,

in which latter event they are magnetically separated into small high grade particles suitable for the ball mill and large particles of all grades which need re-treatment by crushing, etc.

In some instances after the initial sizing and grading we find it advisable and advantageous to efi'ect a two or three-part separation-for example by means of apparatus diagrammatically illustrated in Fig. 5by which a group of particles which would-fall in the space Y, for example, in the illustration in Fig. 2, are subjected to sizing and grading to cast out the larger tailing particles which in the first separation were considered smaller tailings, and which, owing to their lesser distance of travel when projected from the drum, fell into space Y, resulting in the rejection of the smaller tailings and enabling us. to collect the latter without further treatment and deliver them for use in road building. By this first and second stage treatment we are enabled to obtain two sizes of tailings as a -by.-product without screening or sorting prior to their delivery and sale.

By effecting a three-class separation in the manner described above, it will be apparent that subsequent grinding of the large low grade tailing particles falling in compartment X is dispensed with, thereby increasing the efliciency of the apparatus, and decreasing wear on the same. Also, further preliminary handling or crushing of the fine concentrates deposited in space Z is dispensed with, thereby further enhancing the efliciency and economy of the apparatus,

4 these fine concentrates, as stated, being suitable for final treatment in the ball mill and concentrator. This leaves only the particles deposited in the middling space Y for subsequent preliminary treatment, as we term it.

In Fig. 4 we have illustrated, by means of a flow sheet diagram, a multi-stage process, in which the rough ore is conveyed by a belt 5, or the like, to the slide 6 which delivers the same to the crushing rolls 7, which perform the preliminary crushing to desired size of mesh, such as 2 inch, for example, the crushed ore falling upon the chute 18. This chute deposits the ore upon the conveyer belt 30, which travels. around the drum 30 and the magnetic drum 30 similar to drum 15, for example, described previously, and a two-part separation is effected thereat, such separation being effected with the aid of the. shed 31, which will divide the ore into large particles for re-treatment, and comparatively fine concentrates which will be carried down the chute 31" to the ball mill conveyer, or the like, not shown. Particles for re-treatment are deposited upon the belt 17 of the next cobber set, the same being similar in general construction to the apparatus shown in Fig. 1 save that'it is utilized to perform a two-part separation, whereby large tailin particles, such as were deposited in space )2 in the apparatus shown in Fig. 1, are carried by the shed 32 to the tailings chute 32'. All particles other than the large tailing particles are deposited by the shed 32 upon a second pair of crushing rolls 33, which perform a second crushing operation, reducing the particles to a second size for further retreatment. Such particles after crushing drop upon the belt 34 to be carried around the cobber drum 34", when they are again separated as in the previous stage, and the retained particles subjected to a third crushing by crushing and separating stage, after which final preliminary concentration is effected, the-last high grade concentrates being taken off at 38 and the final separation effected by cobber 39, the tailings being conveyed away at 40, and the finally retained material taken away at 41.

It will be obvious that as many stages as are found necessary or desirable may be provided according to the nature of theore to be treated, but it will be apparent that in any case each stage results in the separation out of the main body of material of one or more portions thereof which need not be retreated, thereby decreasing the amount of power, the cost of operation, etc., with each stage. A number of the larger particles in each stage may contain metal in pockets or spots, rather then evenly distributed, and each crushing, breaking down these particles and decreasing their size, renders the concentration of the higher grade particles more easy, as the tailing particles or gangue are broken up and away from the metalliferous particles. Each crushing also results not only in the formation of particles small enough'to pass a sizing mesh, or the like, but in the formation of dust and very small particles, which need not be recrushed and are. suitable for conveyance to the final grinding mill.

In Fig. 5 is shown another form of arrangement in flow sheet form, varying from that shown in Fig. 4 in that the cobber 30 effects a three-class sizing or separation such as was described in connection with the apparatus shown in Fig. 1, the fine concen-, trates' being taken off at 50, the middlings being carried by chute 51 to crushing rolls 33, and the tailings deposited b the shed 52 upon the second cobber belt 1 for a resizing, which will result in the tailings. or gangue being taken off at 53, these being of substantially large size, and those worthy of further treatment being carried with the rolls 35, and so on through a fourth middlings to the rolls 33. In this operation attraction from the magnet poles, and will require greater magnetic attraction for sizing than small finely ground particles of high magnetic susceptibility, which, by virtue of their smallness,- are nearer the magnet poles. The subsequent stages of sizing in the form of apparatus shown in Fig. 5 are similar to thatjust described, and terminate with a final separation as in the form shown in F i 4.

In iig. 6 is shown a similar form of apparatus, in which the first cobber 30 of each set effects a three-class separation, as in the apparatus of Figs. land 5, the tailings of large size being taken off at 60, the middlings carried to the crushing rolls 33, and the fines or high grade concentrate being taken ofl' at 61, this process being repeated until the final sizing or separation.

In carrying out our process, particles of iron, steel, and the like, such as broken tools, implements, etc., which cannot be magnetically removed in the treatment of mag-.

netic ores, are easily taken care of in such way as to prevent damaging of the crushing rolls, as is frequently found in present daypractice. The ore, as it is conveyed to the first crushing roll, is hand picked for the removal of large particles of tool steel, or the like, resulting from broken. drills,

- picks, etc., which large particles are readily removable and visible during the conveyance of the ore to the first crushing rolls. Small particles will readily pass between such rolls, and upon the first magnetic sizing operation, owing to their complete iron constituency they will be carried by the cobber belt to the concentrate collection place, and can then be conveyed with such'concentrates directly to the ball mill, where, instead of causing damage,- they assist in the final grinding or pulverizing of the concentrates.

We are aware, as stated in the preamble, that it has been customary to utilize 'magnetic cobbers heretofore for crude concen-' tration or separatiombut 'so far as we know weare the first to utilize apparatus of this character for classification which effects not only a grading as to mineral content, but simultaneously a sizing; and we are also the first to carry out such a process, the importance of which will be obvious to those skilled in the art. Also, as stated in effect above, each separation stage of our process results in the removal of the large tailing particles as well as the fine high grade particles, the former of .Which would ordinarily have tobe crushed andrecrushed, 'as well as screened. The crushing of this rejected material is therefore eliminated, as is further preliminaryhandling of the dust and high grade fines. As stated also the use of screens and bucket elevators is eliminated, resulting in great economy of vcost and labor. Y

It will be obvious that the apparatus for carrying out our process may be variedin numerous ways, and modified, without de-.

parting from the spirit of theinvention; and

we do not therefore wish to be restricted to the processhereinbefore described, except as defined in the appended claims.

.tlon.

5. A process of sizing and grading ore What we claim is:

1. A process of sizing and gradin ore consisting in imparting a desired velocity to a body of ore particles, then subjecting said particles to a magnetic attraction to Withdraw substantially all save large tailing particles from said ore body, then subjecting the remainder of said ore particles to magnetic attraction of such stren th as to withdraw the fine concentrates rom the middling and lar e high-grade particles.

2. A process 0 sizing and grading ore consisting in imparting a desired velocity to a body of ore particles, then subjecting said particles to a magnetic attraction to withdraw substantially all save large tailing particles from said ore body, then subjecting the remainder of said ore particles to mag.- netic attraction of such strength as to withdraw the'fine concentrates fromthe middling and large high-grade particles and lastly submitting said concentrates to a final magnetic attraction to complete said lastnamed separation.

3. The process of sizing and grading ore consisting in imparting velocity to a body of ore particles in a substantially horizontal direction then subjecting said particles of ore to a magnetic attraction whereby the large tailing particles will be permitted to travel in a substantially parabolicpath while the remainder of said particles will be separated therefrom, then subjecting such remainder to a magnetic attraction at such strength as to release the middling and large high-grade particles while withdrawing the fine concentrates therefrom.

4. The process of sizing and grading ore consisting in'imparting velocity to abody of ore particles in a substantially horizontal direction then subjecting said particles of ore to a magnetic attraction whereby the' large tailing particles will be permitted'to 'travel in a substantially parabolic path while the remainder of said particles will be separated therefrom, then subjecting such high-grade particles while withdrawing the r fine 'concentratestherefrom, and finally continuing last separation by subjecting said concentrates to a further magnetic attracc'onsistingin imparting velocity to a body of ore particles then subjecting said particles to a magnetic attraction to withdraw all save the large tailing particles then subjectingsaid withdrawn particles to a relatively Weak magnetic attraction to disassociate the middling and large high-grade particles from the fine concentrates.

6. A process of sizing and grading ore consisting in impartingv velocity to a body of ore particles then subjecting said particles to a magnetic attraction to Withdraw all save the large tailing particles then subjecting said Withdrawn particles to a relatively weak magnetic attraction to dis-associate the middling and large high-grade particles from the fine concentrates, then subjecting such fine concentrates to a relatively strong attraction to continue said last separation.

In testimony whereof, we have subscribed 10 our names.

WALTER G. SWART.

FRED A. JORDAN.

EDWARD W. DAVIS;

THEODORE B. COUNSELMAN. Witnesses:

LYDIA M. WVOODBRIDGE,

H. N. MAOHAIG.

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