US 1678884 A
Description (OCR text may contain errors)
A. T. SWEET METALLURGICAL SEPARATOR July 31, 1928.
Filed Oct. 21, 1926 Q72 62 7610 Z j aeff Patented July 31, 1928.
UNITED STATES PATENT OFFICE.
ANDREW T. SWEET, OF HOUGH'ION, MICHIGAN, ASSIGNOR OF ONE-FOURTH f0 WIL- LIAM G. RICE AND ONE-FOURTH T0 HERMAN GUNDLACH, BOTH OF HOUGHTON, MICHIGAN, AND ONE-TENTH 'I'O PHILIP 1B. WQODWDBTH, OF CHICAGO, ILLINOIS.
Application filed October 21, 1926. Serial No. 148,132.
This invention relatesto improvements in machines for separating materials according to the amount of light reflected thereby, and is more particularly adapted for selecting bright objects from a heterogeneous mass of mainly duller objects, and is specially adaptable for the mechanical separation of certain ores from others or from the gangue, such as copper from silver, gold from quartz, lead from the gangue, and zinc or any other material from its gangue or associated minerals.
Heretofore hand picking was the only available method for separating ores which were of substantially the same specific gravity and. therefore could not be separated by the gravitational methods or which did not respond to'the other well-known methods, such as acid or electrolytic treatment. The hand picking method is naturally somewhat uncertain, and becomes very expensive where low rades of ore are handled or where it is on y desired to remove a very small proportion of foreign material from a common ore, as for example, the separation of arsenites from certain copper ores. A! very small percentage of arsenic will greatly re duce the conductivity of copper, and it is found that the difference in the reflecting value of the copper associated with the arsenites is sufl'icient to enable the separation by means of this invent-ion.
The main objects of this invention are to provide an improved and economical machine for separating certain minerals from other minerals by means of mechanism sensitive to light reflected by the materials; to provide improved means for intensifying the light reflecting qualities of the different materials so that the selection is more easily accomplished; to provide an improved machine of this kind which will operate continuously and in which a very small quantity of certain materials may be economically selected from a comparatively large aggregate mass and to provide advantageous improvements in the selecting device and also the arrangement and construction of such a machine.
An illustrative embodiment ofthis invention is shown in the accompanying drawings, in which:
ig. 1 is a diagrammatic sectional iew of the separating machine,
Fig. 2 is a cross sectional view of the selecting device.
Fig. 3 is a fragmental plan view of a portion of the conveyor, showing a plurality of trap doors.
In carrying out this invention, the ore is first reduced to roughage or a loose mass, and is then fed in a thin layer along a path which is in the range of a light-sens1tive selector, such as a selenium cell, adapted to react to the light reflected from the bright particles in the stream, andthrough electrlcal devices operate a trap door in the conveyor line to dump the portion containing the bright particle out of the stream.
I The effectiveness of the device may be increased by a pre-treatment of the ore by pyro-metallurgical or hydro-metallurgical processes to intensify or change the color and brightness of the various substances. This may be accomplished by treating the ore in the bin, or, preferably, by treating the ore while it is traveling along the con-' veyor. It is also found that, by pretreating in a suitable manner, difl'erent materials may be removed from the same ores. The selected portions may be dumped by a trap door into a hopper and run through the separator repeatedly until a desired degree of separation has been accomplished.
After the trap door is dropped, it is at once returned to the normal closed position, so that the stream may continue to move by, the trap door remaining closed until a bright object is again carried into the range of the selecting device.
Referring to the drawings, concentrates, or ore roughage, are fed from the chute 1 into the distributory box 2, which spreads the ore out in a thin stream on the conveyor belt 3. If it is desired to treat the ores, the conveyor belt travels through an appropri ate device, as for example, a heating oven 4.
The stream of material is fed into the upper end of the inclined chute or trough 5, which is slidably mounted on suitable supports 6, and reciprocated or shaken by means of the eccentric connection 7 to a continuously rotating shaft 8. This causes the stream to move steadily down to the lower end of the trough 5 with a certain amount of agitation.
In this manner, the thin stream of ore is moved over the trap door 9, which is p sh tioned in the range of the selector 10., The door 9, of which a plurality may be used as shown in Fig. 3, is pivotally mounted in the bottom of the trough 5, to swing downwardly. Normally the door isheld in the.
raised position in alignment with the bottom of the trough 5, by means of the spring 11. A depending lever 12 is rigidly secured to the door hinge 13, and is engaged by the pawl 14, which is pivotally mounted in the solenoid plunger 15 to yield in one direction. The plunger 15 is attracted by the solenoid 16, when energized, and is returned to the position shown in Fig. 1' by means of the spring 17. After the door is swung down a short distance, the pawl 14 becomes disengaged from the end of the lever 12 to allow the door to be returned into normal position by the spring 11, and, on'the return movement of .the solenoid, the pawl 14 yields to pass the end of the lever 12.
The detector comprises a selenium cell 18, which is mounted in the upper end of a short tube 19, which is in angular relation with a larger tube 20, in which is mounted a lamp 21 associated with a reflector 22. The arrangement is such that the rays of light from the larger tube 20 strike the surface of the stream of. material 23.and are reflected back into the tube 19 to strike thecell 18. The effectiveness of the detector may be materlally increased by providing a suitable lens 24 in the lower end of the. tube 19 to collect the rays of light andfocus' the same on the small portion of the cell 18. The cell 18 is connected in circuit with the variable resistance 25 to the relay coil 26 and the battery 27. The efi'ect "of the light on the cell 18 is to decrease the electrical resistance, therethrough, and the resistance 25 vis so adjusted that the heavier currents which are permitted to flow under the reaction of the cell from-the light reflected from the brighter"objects is sufiicient to cause the solenoid 26 to attract the armature 28. The'armature 28 is normally held away from the solenoid 26 by means of the adjustably tensioned spring 29, against a sultable stop 30. The armature 28 is connected to one terminal of the solenoid 16, and the opposite terminal of the solenoid 1 6 is connected through the battery 31 to, the terminal 32, which is contacted by the armature 28, when attracted by the relay 26.
It is now manifest that, when a sufiiciently bright particle moves over the door and into the range of the selecting device 10, the solenoid 26 is energized to close the energizmg circuit of the solenoid 16. This causes the solenoid 16 to retract the plunger 15, to drop the door 9 and dump the section of material into the suitably positioned receiving hopper 31. As soon as the door drops down, the amount of light reflected into the cell tube 19 is decreased below the A ray of light from the surface of such material as native silver will change the electrical resistance of the selenium cell to operate the dumping device and divert the silver containing portion from the main stream of copper concentrates. In such ores the action may be made more positive bypreheating the ore to a dull red heat. This coats the copper with cuprous oxide, which is dark brown, and cupric oxide, which is black. Substantially all of the silver may beremoved, and, by pretreating the removed material, a substantially'clean silver concentrate may be obtained. B means of this apparatus the detrimental arite may be removed from the iron ore; also different forms of a single substance may be separated, such as" the crystalline form of graphite and the amorphous graphite. When necessary, the selector may be operated on extremely fine material by using the lens, or the lens ma be used to enlarge the area of the spot WhlCh is in effective range.
Although but one illustrative embodiment of this invention has been shown and described, it will be seen that numerous details of the device shown may be altered or omitted without departing from the spirit of the invention, as defined in the following claims.
1. A process for separating minerals from ore which consists in causing the ore to move in a stream across a beam of light and dividing out of said stream fractional masses until a desired degree of separation has resulted.
3. An ore treatment process for separating certain ,minerals from masses of the ore, which consists in heating the orefor the purpose of oxidizing and thereby changing the light reflecting values of certain metallic ingredients thereof, then causing the ore to move in a stream across a beam of light and dividing masses of the ore out of said stream according to light reflecting values.
4. An ore treatment process for separating certain minerals from masses of the ore, which consists in heating the. ore for the purpose of oxidizing and thereby changing the light reflecting values of certainmetallic ingredients thereof, then causing the ore to move in a stream across a beam of light and dividing masses of the ore out of said stream according to light reflecting values, and repeating the same process on the masses divided out until a desired degree of separation has resulted.
5. An ore treatment process for separating minerals from masses of the ore, which consists in first treating the ore for changing the normal light reflecting values of certain metallic ingredients thereof, then causing the ore to move in a stream across a beam of light and dividing masses brt'hbrebut of door, a trip for opening said door, said trip being stationed in position to engage and open said door when the chute is reciprocated relatively of said trip, electromagnetic means for rendering said trip operative or inoperative, and electrical control means for said electromagnetic means arranged to be subject to operation by the varying intensity of light reflected from the ore in said chute over the trap door thereof.
Signed at Houghton, Michigan, this 18th day of October, 1926.
ANDREW T. SWEET.