US3356211A

US3356211A - Separation of ore particles preferentially coated with liquid fluorescent material

Info

Publication number: US3356211A
Application number: US416293A
Authority: US
Inventors: Ted C Mathews
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-12-07
Filing date: 1964-12-07
Publication date: 1967-12-05
Anticipated expiration: 1984-12-05
Also published as: OA02048A; SE311501B; DE1237512B; GB1078430A; FR1475692A

Description

Dec. 5, 1967 T. c. MATHEWS 3, SEPARATION OF ORE PARTICLES PREFERENTIALLY COATED WITH LIQUID FLUORESCENT MATERIAL Filed Dec. 7, 1964 O 4=9e9 coeaaavw @O INVENTOR. 750 CI M4 Iva 5W5 United States Patent 3,356,211 SEPARATION OF ORE PARTICLES PREFEREN- TIALLY COATED WITH LIQUID FLUORES- CENT MATERIAL Ted C. Mathews, P.0. Box 2061, Fairbanks, Alaska 99701 Filed Dec. 7, 1964, Ser. No. 416,293 7 Claims. (Cl. 209-9) ABSTRACT OF THE DISCLOSURE The patent describes a method for the concentration of ore by subjecting a quantity of crushed ore containing various types of minerals to electromagnetic radiation to cause at least a portion thereof to fluoroesce at a characteristic wavelength distinct from that of the rest of the ore mass, and sensing the characteristic wavelength emitted by the radiated particles. The fluorescence of at least one portion of the ore at characteristic wavelength distinct from that of the rest of the ore is achieved by the preferential coating of some of the ore particles with a liquid fluorescent material.

A common condition in many mining operations requires the mining of large quantities of worthless rock and the like to permit the recovery of the valuable mineral portion. The mill must then crush, grind and treat all of this material to extract the desired mineral.

To reduce the mill load it is desirable to reject at the mine the worthless material. In the instance where strong visual contrast exists between the mineral and the worthless portion, the mineral is often picked by hand to up grade the feed for the subsequent crushing and grinding operations. Heretofore, it has also been proposed to automatically separate the mineral from the worthless portion by means which detect the difference in the natural color or radioactivity of the mineral and the worthless portion. However, these techniques have limited utility since at many mines visual or radioactive contrast does not exist and hence, these ores may not be treated economically in this way.

According to the present invention, it has now been found that the desired mineral may be separated from the worthless portion by radiating the ore to cause a portion of it to emit at a characteristic wavelength and sensing the emitted rays. The sensed rays are used to operate means for separating the ore into a desired and an undesired portion. In a preferred embodiment, it has been found that the desired separation may be achieved by first treating a quantity of the ore with a liquid which preferentially coats the particles of one of the portions of the ore and is also capable of emitting at a characteristic wavelength upon exposure to ultraviolet light, X-rays, or other suitable type of electromagnetic radiation. The treated ore is then passed to a separation zone where an electromagnetic wave means sensitive to the characteristic wavelength detects which particles are coated and which particles are not. The sensing means then functions to actuate a deflecting means which physically removes the coated particles from the body of ore particles. Thus, a desired or undesired type of mineral may be removed from the mass of ore.

3,356,2ll Patented Dec. 5, 1967 It is an object of this invention to provide a method for the treatment and concentration of ores.

It is another object of this invention to provide a process of preferentially coating one portion of a mass of ore-bearing rock with a liquid material which, when excited by exposure to electromagnetic radiation, emits radiation of a wavelength distinct from that of the rest of the mass.

It is another object of this invention to pass radiated Ore through a zone where the radiation emitted by the particles is received in an electromagnetic wave-sensitive element and certain of the radiated particles are automatically rejected in accordance with the selective response of the electromagnetic wave-sensitive element to the characteristic emissions therefrom.

These and other objects of this invention will become apparent from the detailed description which follows.

According to this invention, a portion of a body of ore is caused to emit a characteristic wavelength, which wavelength is unlike that emitted by the rest of the ore. The ore particles are then separated according to whether they emit the characeristic wavelength. This is preferably accomplished in the following manner. A quantity of ore containing at least one valuable mineral portion is first treated with a liquid which preferentially coats the particles of one of the minerals in the ore. The coating liquid, in adition to being specific to particles of one of the minerals in the ore, is also capable of fluoroescing at a characteristic Wavelength after exposure to ultraviolet, X-rays, or any other suitable type of radiation. For this reason, the coating liquid is sometimes referred to as the fiuoroscent material. I

The radiation and separation of the ore will be better understood by reference to the accompanying schematic drawing depicting these aspects of the process of this invention. The ore, which in the preferred embodiment has been treated with the fluorescent material to provide both coated and uncoated particles, is placed on a conveyor 1 and caused to drop from the end of conveyor in a downward path past a radiation source 2, into a zone where the characteristic radiation emitted by the radiated particles is received in an electromagnetic wave-sensing means 3. The wave energy received by means 3 produces a small current which is amplified by an amplifier 4. The output of the amplifier then triggers a rectifier switch 5 which, in turn, energizes deflecting means 6, normally a solenoidoperated air jet, water jet, or mechanical gate. The deflecting means knocks the particle emitting at the characteristic wavelength out of the stream of ore particles. These particles are received in collector 7, with the balance of the particles falling into collector 8.

While in the preferred method, a portion of the ore particles is preferentially coated to provide the characteristic emissions upon excitation, the coating may be dispensed with in the case of natural iluorescing ores. These ores, upon excitation, emit at a characteristic wavelength which can be used to activate separation. Typical materials that can be recovered from ore mixtures without coating or other pretreatment are willemite, hydrozincite, uranite, calcite and sheelite. Other ores separated by the technique of this invention are first pretreated to provide a preferential coating capable of emitting at a charactersitic wavelength upon exposure to one of the many forms of electromagnetic radiation.

In this specification, the ore particles which emit at a characteristic wavelength upon excitation will sometimes be referred to as being fluorescent. Likewise, the coating materials used in many cases to provide this property will be referred to as fluorescent materials. In a narrow sense, fluorescence refers to the property of absorbing radiation at one particular Wavelength and re-emitting it as light of a different wavelength so long as the stimulus is active. However, I intend by fluorescence to indicate that property of absorbing radiation at one particular wavelength and re-emitting it as a different wavelength, whether or not visible, during exposure to the active stimulus, or after exposure, or during both of these time periods. Thus, fluorescence is used generically herein to include the limited definitions of both fluorescence and phosphorescence, and envisions the emission of a characteristic wavelength whether or not visible.

In the preferred process, a wire variety of organic materials which fiuoresce at a characteristic wavelength upon excitation by ultraviolet light, X-rays, or other radiation may be used to preferentially coat either the desired or the undesired portion of the ore. Illustrative of these organic fluorescent substances are anthracene, fluorescein, chrysene, aminoacetal picrate, petroleum base lubricating oil, allylamine picrate, aluminum palmitate, ammonium mandelate, calcium triethanolamine theobroinine, ferrous stearate, glyceryl monooleate, glyceryl monostearate, hydrastine, hydrastine chloride, lead naphthenate, lead linoleate, lead stearate, manganous stearate and benzene. Certain of these materials are solids at ordinary temperatures and hence are used in solution. For example, anthracene may be dissolved in benzene.

To assist in adhering the fluorescent substances to the particles to be coated, there may be optionally employed any one of a number of bonding agents, hereinafter referred to as collectors. The collectors are usually long chain molecules with an atomic group which orients on the particle surface and another group which orients on the fluorescent substance. While not bound by any theory, it is believed that the collector is preferentially absorbed on the mineral surface and displaces the water film normally present thereon.

Collectors may be of any one of several types and are generally classified on the basis of their surface attachment into three groups-anionic, cationic and neutral. Anionic collectors usch as xanthates adhere to minerals with a positive surface potential such as metals and sulfides. Cationic collectors usch as amines adhere to surfaces having a negative charge such as silicates. The neutral collectors such as petroleum derivatives adhere to surfaces more positive than the neutral hydrocarbon.

As has been already indicated, the use of a collector is not always require-d. For example, many petroleum base lubricating oils will both preferentially adhere to certain minerals and also fluoresce when excited by electromagnetic radiation. The following list is merely illustrative of some of the anionic collectors which may be employed in this invention: the alkali alkyl xanthates, such as sodium sec-butyl xanthate, potassium ethyl xanthate, sodium ethyl xanthate and potassium amyl xanthate; aryl dithiophosphoric acids such as phenyl dithiophosphoric acid; fatty acids such as stearic acid; thio carbanilide; saponified fatty acids such as sodium stearate and potassium stearate; sulfonated oils; glycerides such as tripalmitin and tristearin; and alcohols.

The cationic collectors include the alkyl ammonium halides such as amyl trimethyl ammonium bromide and cetyl trimethyl ammonium bromide; the alkali metal and alkaline earth metal alkyl aryl sulfonates such as sodium dodecyl benzene sulfonate and calcium dodecyl benzene sulfonate; the alkyl ammonium acetates such as dodecylammonium acetate; long-chain alcohols such as dodecyl alcohol; ethylenically unsaturated monocarboxylic acids and their soaps such as oleic acid, linoleic acid, sodium oleate and sodium linoleate; fatty amine acetates; and benzene.

The fluorescent material and the collector, if present, may be applied to the ore in a variety of ways, including spraying and dipping. In practice, the fluorescent material is added to the collector prior to ore treatment. However, the ore may be treated with the collector and the fluorescent material sequentially. Any excess of the fluorescent material or collector may be readily removed by washing with water.

A fluorescent ore, or the fluorescent material preferentially absorbed on some of the ore particles can be caused to fluoresce at a characteristic wavelength by radiation from the full spectrum of electromagnetic energy, varying from radio waves through infrared, visible, ultraviolet, gamma rays, and ionic bombardment. The specific type of radiation employed in any given situation will depend upon the particular fluorescent material being used. For example, anthracene and petroleum base lubricating oils upon exposure to ultraviolet light (25003700 angstroms) will fluoresce strongly at about 4000 angstroms.

By appropriately selecting the fluorescent material and collector, it is possible to coat almost any mineral in preference to any other material present. Thus, by my invention, any ore portion, whether naturally fluorescent or not, may be readily separated from any other portion. It will, therefore, be recognized that the following examples are presented solely to illustrate the invention and should not be regarded as limitative in any way.

Example I A quantity of crushed ore containing primarily quartz and calcite is coated with a petroleum base lubricating oil (sold by the Standard Oil Co. under the name Penn Motor Oil SAE 30). The excess lubricating oil is removed by flushing with water. Microscopic examination of the particles reveals that the quartz rejects the lubricating oil while coating the calcite. The apparatus used to separate the ore includes a conveyor having an ultraviolet light source stationed at its discharge end. Below the ultraviolet source is positioned a 931-A photo multiplier tube sensitive to 4000 A. emissions. A Wratten filter is interposed in the optical path of the tube to eliminate stray ultraviolet. The output of the tube leads to an amplifier which triggers a silicon controlled rectifier switch which, in turn, energizes a solenoid-operated air jet located below the ultraviolet source. The treated ore is placed on the moving conveyor belt at a rate which provides a single layer of ore particles. The ore particles are exposed to ultraviolet light as they leave the end of the conveyor and'are in free fall. The 4000 A. emissions from the coated particles are sensed by the photo multiplier tube. It is found that the air jet deflector actuated by the tube produces a high degree of separation of the coated calcite from the quartz.

Example II A quantity of crushed ore containing quartz, sandstone, argillite, schist, quartzite and calcite is first washed to remove adhered particles. The ore is then sprayed with an aqueous mixture of dodecylammonium acetate and anthracene dissolved in benzene. The ore is then washed with water to remove the coating solution from the unwanted portions and to leave a coating of anthracene only on the quartz particles. The quartz is then separated from the rest of the ore according to the procedure and employing the apparatus described in Example I.

Example III A quantity of crushed ore containing sulfide minerals, sandstone, argillite, schist and calcite are washed with water to remove adhered particles. The ore is then washed with an aqueous solution of anthracene and phenyl dithiophosphoric acid. The excess is removed by washing with water. It is found that the anthracene preferentially adheres to the surface of the sulfide minerals. The sulfide mineral is then effectively separated from the bulk of the ore in the manner set forth in Example I.

In the practice of the process of this invention, separations of 90% of efficiency have been achieved, using a variety of ores including the following:

Quartz from Quartzite Sandstone Argillite Calcite Mica schist Calcareous schist Hornblend schist Limestone from- Quartz Sandstone Argillite Calcite Mica schist Calcareous schist Hornblend schist As can be seen from the foregoing, the process of this invention is particularly well suited to the concentration of quartz, calcite and limestone-containing ores.

The wave sensing means 3 is typically a photo multiplier tube having a sensitivity to specific wavelength bands. The bands received at the sensing means are narrowed, as required, by the use of filters. Tubes are cornmercially available having sensitivities from the infrared to the ultraviolet. Thus, it is a simple matter to select a tube which is sensitive to the characteristic wavelength emitted upon electromagnetic excitation of any given fluorescent ore or material.

In these photo multiplier tubes, photons which result from fluorescence are received in a first stage and converted to electrons which are deflected to succeeding states by electrostatic fields and multiplied by secondary emission from each stage. The weak current emerging from the photo multiplier tube may be amplified in a conventional solid state amplifier. Since the current from the amplifier is used to operate deflection means 6, it is usually necessary to incorporate an adjustable delay network in the amplifier in order to achieve register between the position of the particle at the time of detection by the sensing means and the time of deflection.

Since the throughput of ore particles in the process of this invention must be as high as possible, the particles are passed before the sensing means at a high velocity. The sensing means is normally placed so that the ore particles passing before it are in free fall and thus have a high velocity and a fixed path.

As can be seen in the drawing, the sensing means is conveniently located so that the sensing means detects the particles soon after they leave the end of the conveyor. To assure a high degree of separation, the ore particles are fed to the conveyor at arate which provides a single layer. While only one sensing means is shown in the drawing, it will be understood that the number of sensing means used is dependent upon the tonnage of ore particles to be handled, the width of the conveyor, and the size of the particles. The field of detection for each sensing means is limited to an area approximately equal to the area of an individual ore particle.

The particular deflecting means 6 chosen has been found to depend on the individual size of the ore particles. An air jet is useful on sizes below /2 inch. A water jet is used on sizes between /2 inch and 4 inches, while a mechanical gate is used for even larger sizes.

While the process of this invention has been described with particular reference to the separation of ore particles while in free fall from the end of a conveyor, it will be evident to anyone skilled in the art that my invention may be practiced in many other ways and with the aid of many different types of apparatus. For example, the particles may be mechanically separated while moving in any desired plane including the horizontal. In the case of small batches, it may be expedient to perform the actual separation manually.

Having fully described the invention, it is intended that it be limited only by the lawful scope of the appended claims.

I claim:

1. The method for the concentration of ore which comprises treating a quantity of crushed ore containing various types of minerals with a liquid fluorescent material capable of preferentially coating some of the particles in the ore, radiating the treated quantity of ore to excite the liquid on the coated particles to fluoresce at a characteristic wavelength, and separating the coated particles from the uncoated particles on the basis of the difference in their emitted wavelengths.

2. The method for the concentration of ore which comprises treating a quantity of crushed ore containing various types of minerals with a liquid fluorescent material capable of preferentially coating some of the particles in the ore, radiating the treated quantity of ore to excite the liquid on the coated particles, passing the radiated treated quantity of ore through a zone where the characteristic wavelength emitted by the radiated coated particles is received in an electromagnetic wavesensitive element, and automatically displacing the coated particles in accordance with the selective response of the electromagnetic Wave-sensitive element to the characteristic wavelength received therein.

3. The method for the concentration of calcite-containing ore which comprises treating a quantity of calcitecontaining ore containing various types of minerals with a liquid fluorescent material capable of preferentially coating some of the particles in the ore, radiating the treated quantity of ore to excite the liquid on the coated particles, passing the radiated treated quantity of ore through a zone where the characteristic wavelength emitted by the radiated coated particles is received in an electromagnetic wave-sensitive element, and automatically displacing the coated particles in accordance with the selective response of the electromagnetic wavesensitive element to the characteristic wavelength received therein.

4. The method for the concentration of quartz-containing ore which comprises treating a quantity of quartzcontaining ore containing various types of minerals with a liquid fluorescent material capable of preferentially coating some of the particles in the ore, radiating the treated quantity of ore to excite the liquid on the coated particles, passing the radiated treated quantity of ore through a zone where the characteristic wavelength emitted by the radiated coated particles is received in an electromagnetic wave-sensitive element, and automatically displacing the coated particles in accordance with the selective response of the electromagnetic wave-sensitive element to the characteristic wavelength received therein.

5. The method for the concentration of sulfide-containing ore which comprises treating a quantity of sulfidecontaining ore containing various types of minerals with a liquid fluorescent material capable of preferentially coating some of the particles in the ore, radiating the treated quantity of ore to excite the liquid on the coated particles, passing the radiated treated quantity of ore through a zone where the characteristic Wavelength emitted by the radiated coated particles is received in an electromagnetic wave-sensitive element, and automatically displacing the coated particles in accordance with the selective response of the electromagnetic wavesensitive element to the characteristic wavelength received therein.

6. The method for the concentration of ore which comprises treating a quantity of ore containing various types of minerals with anthracene to preferentially coat some of the particles in the ore, radiating the treated quantity of ore to cause the anthracene on the coated particles to fiuoresce, passing the radiated treated quantity of ore through a zone where the characteristic wavelength emitted by the radiated coated particles is received in an electromagnetic Wave-sensitive element, and automatically displacing the coated particles in accordance with the selective response of the electromagnetic wavesensitive element to the characteristic wavelength received therein.

7. The method for the concentration of ore which comprises treating a quantity of ore containing various types of minerals with a petroleum base lubricating oil to preferentially coat some of the particles in the ore, radiating the treated quantity of ore to cause the lubricating oil on the coated particles to fiuoresce, passing the radiated treated quantity of ore through a zone Where the characteristic wavelength emitted by the radiated coated parti- 8 cles is received in an electromagnetic wave-sensitive element, and automatically displacing the coated particles in accordance with the selective response of the electromagnetic wave-sensitive element to the characteristic wavelength received therein.

References Cited UNITED STATES PATENTS 1,577,328 3/1926 Lewis 209 -167 2,096,099 10/1937 Gaugler 250--71 2,267,999 12/19'41 Switzer 250-71 2,717,693 9/1955 Holmes 209-1115 2,878,392 3/1959 Polito 25071 3,011,634 12/1961 Hutter 209111.5 X 3,016,143 1/1962 Trachta 209-167 X 3,061,723 10/1962 Kaptf 250-71 3,118,060 1/1964 Klein 25071 3,255,881 6/1966 Holderreed 209--164 X FRANK W. LUTTER, Primary Examiner.

Claims

1. THE METHOD FOR THE CONCENTRATION OF ORE WHICH COMPRISES TREATING A QUANTITY OF CRUSHED ORE CONTAINING VARIOUS TYPES OF MINERALS WITH A LIQUID FLOURSCENT MATERIAL CAPABLE OF PREFERNTIALLY COATING SOME OF THE PARTCLES IN THE ORE, RADIATING THE TREATED QUANTITY OF ORE TO