The present disclosure relates to systems and methods for separating or concentrating material of higher specific gravity from material of lower specific gravity, such as heavy metals from a fluid or slurry.
It is often desirable to extract particular materials, such as heavy metals, from their surrounding materials, but the desired materials can be present in low concentrations relative to the surrounding materials and therefore difficult to extract. For example, mining operations generate streams of mixed materials, from which desired materials are concentrated and extracted. Mining operations, however, generally fail to extract all of the desired materials, due to the limitations of technologies for concentrating and extracting specific materials from the mixed material streams produced by mines. Many historic mines also utilized inferior extraction technologies, thus leaving tailings containing significant quantities of valuable materials. Additionally, historic mines produced tailings with a large quantity of materials, such as rare earth metals, that were not be extracted during operation of the mine, due to technological or economic factors (e.g., the cost of extracting such materials may have greater than the value of recoverable materials given the technology available at the time). Modern mining operations are also constantly seeking cheaper and more efficient technologies for recovering desired materials. Similarly, industrial processes can produce waste that includes harmful elements that should be extracted for environmental, regulatory or safety reasons.
The present disclosure relates to systems and methods for recovering low concentration target materials, such as heavy metals, from surrounding materials.
Various examples of methods and apparatus for recovering target materials from mixed materials are disclosed. Without limiting the scope of the claims, some prominent features of this disclosure will now be briefly described.
One aspect of the disclosed technology is a device for separating a first mineral of a first specific gravity from at least a second mineral of a second specific gravity that is lower than the first specific gravity. The device includes a centrifuge configured to rotate about an axis. At least one collection region is configured to be subject to centripetal acceleration when the centrifuge rotates about the axis. At least one energy injection module is coupled to the collection region and configured to provide oscillating energy into the collection region. The collection region and energy injection module are configured to stratify the first and second minerals.
In some embodiments, the energy injection module is configured to provide acoustic energy into the collection region. The energy injection module can be configured to provide acoustic energy at a subsonic frequency. The energy injection module can be configured to provide acoustic energy at a plurality of frequencies simultaneously.
In some embodiments, the energy injection module is configured to provide oscillating pressure waves into the collection region. The energy injection module can be configured to provide oscillating energy into the collection region such that the oscillating energy propagates into the collection region along a direction substantially parallel to the centripetal acceleration at the collection region.
In some embodiments, the device additionally includes a membrane between the collection region and the energy injection module.
In some embodiments, the centrifuge is configured to receive the first and second minerals in slurry. The centrifuge can also be configured to circulate the slurry across the collection region as the centrifuge rotates about the axis.
In some embodiments, the device additionally includes at least one spring that acts on the energy injection module and that counters at least part of the centripetal acceleration on the energy injection module.
In some embodiments, the device additionally includes at least one sensor that measures an amount of material present in the collection region. For example, the device can include at least one sensor that measures the mass of material collected in the collection region.
Another aspect of the disclosed technology is a method for separating a first mineral of a first specific gravity from at least a second mineral of a second specific gravity that is lower than the first specific gravity. The method includes obtaining a fluidized slurry containing the first and second minerals. The slurry is spun in a centrifuge such that the slurry is circulated within the centrifuge and across at least one collection region. At least a portion of slurry is received in the collection region, which is subjected to centripetal forces due to the rotation of the centrifuge about the axis. Energy waves are generated and injected into the collection region. The first and second minerals are stratified in the collection region.
In some embodiments, generating the energy waves comprises generating acoustic waves. For example, generating the acoustic waves can comprise generating subsonic waves. Generating the acoustic waves can also comprise generating acoustic waves at a plurality of frequencies simultaneous.
In some embodiments, generating the energy waves comprises generating pressure waves.
In some embodiments, generating the energy waves comprises generating at least one standing wave in the collection region.
In some embodiments, obtaining the fluidized slurry comprises grinding the first and second minerals such that the first and second minerals have a maximum particle size of 100 microns and adding a fluid to the first and second minerals.
In some embodiments, the method additionally includes, while the centrifuge is rotating, weighing material collected within the collection region.
In some embodiments, generating the energy waves comprises generating the energy waves with an energy injection module separated from the collection regions by a moveable membrane, and the method also includes, while the centrifuge is rotating, determining a weight of material collected within the collection region based on a measured deflection of the moveable membrane and based on a rate of rotation of the centrifuge.
Throughout the drawings, reference numbers may be re-used to indicate correspondence between referenced elements. The drawings are provided to illustrate example embodiments described herein and are not intended to limit the scope of the disclosure.
Reference will now be made to the drawings, in which like reference numerals refer to like parts throughout. Unless indicated otherwise, the drawings are schematic not necessarily drawn to scale.
A system 100 for separating minerals by specific gravity with a centrifuge 108 is shown in
In
In at least some embodiments, centrifuge 108 may be operated in a reduced or zero gravity environment such as in orbit around a celestial body or on the surface of a natural or artificial object other than Earth. If desired, centrifuge 108 may be modified for operation in low gravity such as by sealing an otherwise open section (such as a top) of the centrifuge 108. As another example, the centrifuge 108 may be integrated into a mobile processing unit (MPU) capable of transporting the centrifuge 108 to a desirable location on a natural or artificial object other than Earth. The MPU may be capable of collecting and pre-processing material (e.g., the MPU may include crushers and/or rotary sieve devices to pre-process regolith or other source materials to a desired grain size). Additionally, the MPU and/or centrifuge 108 may include augers or paddles to assist in the movement of materials through the centrifuge 108 and related components (e.g., input hoppers, output hoppers, etc.), which may be particularly beneficial in low gravity environments where gravity cannot be relied upon for moving materials. In some embodiments, the MPU may include internal and/or external storage for storing valuable materials such as concentrate 116. As a particular example, the MPU may include mechanisms for robotically removing saturated collection cells (such as collection region 144 and collection regions 210a, 210b) from the centrifuge and storing the saturated collection cells for later collection.
In various embodiments, centrifuge 108 may be operated in environments of varying temperatures (e.g., environments on Earth, in space, or on the surface of objects other than Earth that are subject to extreme cold, extreme heat, or both). If desired, centrifuge 108 may be modified for operation in environments of different temperatures such as extreme cold or extreme heat. As one example, a cold-tolerant fluid such as ammonia may be utilized as fluid 104 when centrifuge 108 is operated in cold environments on Earth or in space. As another example, cold-tolerant materials (e.g., materials that are not excessively brittle and retain sufficient structure strength at low temperatures) may be used in forming the structure of centrifuge 108. As yet another example, centrifuge 108 may include heating elements that heat centrifuge 108, fluid 104, slurry 106, and/or other components of centrifuge 108. In environments such as the Moon, mined materials such as regolith may be excessively hot at the surface and excessively cold below the surface. In such environments, centrifuge 108 may be fed with a selective mix of surface regolith and subsurface regolith to achieve a desired temperature of the working materials (e.g., such that feed source 102 is within a suitable temperature range).
If desired, alternatives to fluid 104 may be used as a medium for material being separated. In particular, fluid 104 may be replaced with a solid medium formed of balls or grains, which may have a larger size than the feed source 102 being separated by centrifuge 108 and such solid carrier medium could be recovered with a rotary sieve or other recovery mechanism. Solid medium alternatives to fluid 104 may be beneficial in overcoming fluid issues in severe temperatures and/or low pressure or vacuum conditions. Embodiments described herein are particularly well-suited to low or zero-gravity and cold environments typical of extraterrestrial applications and can operate without human intervention.
In some embodiments, the feed source 102 may include tailings or other similar materials that have been ground to a suitable particle size or to a suitable range of particle sizes. As an example, the feed source 102 may include materials that have been ground, or otherwise processed, such that the nominal maximum particle size in feed source 102 is a range of about 50 microns to 200 microns, for example, about 100±15 microns. In some embodiments, feed source 102 may be combined with a fluid 104 such as water or ammonia to form slurry 106 (e.g., fluidized slurry 106). Fluid 104 may include any suitable fluid and, if desired, may include chemicals that aid in stratification by specific weight within the centrifuge 108. As an example, the fluid 104 may include lubricants, surfactants, and other chemicals that facilitate or accelerate stratification by specific weight within the centrifuge 108. As another example, the fluid 104 may include anti-freeze additives that lower that freezing point of the fluid, which aid in preventing freezing of fluid 104 when centrifuge 108 is operating in cold environments, such as extraterrestrial environments. As noted above, in various embodiments, slurry 106 may be created inside centrifuge 108 by separately adding fluid 104 and feed source 102 into centrifuge 108.
Slurry 106 may be processed by the centrifuge 108 to produce concentrate 116 and tailings 114. As depicted in
In some embodiments, slurry 106 may be processed by multiple centrifuges 108 coupled together in series, where each centrifuge processes the reject material, or tailings 116, from a prior centrifuge. In such embodiments, multiple stages of centrifuges coupled together in series may be configured to separate a variety of materials out of slurry 106. As an example, an initial stage formed of one or more centrifuges may separate out a first material of a first specific weight, a second stage formed of one or more additional centrifuges may receive the tailings from the initial stage and may separate out a second material of a second specific weight less than the first specific weight, a third stage formed of one or more additional centrifuges may receive the tailings from the second stage and may separate out a third material of a third specific weight less than the second specific weight, and so on for as many stages as desired. Such embodiments may allow processing of a spectrum of many materials from high to low specific weight from a particular feed source.
In some embodiments, multiple centrifuges 108 may be coupled together in parallel to increase processing speed and/or volume. In other embodiments, configurations of both serial and parallel couplings are provided. As an example, system 100 may include a first stage formed from one or more centrifuges 108 coupled together in parallel and the first stage may be coupled in series with at least a second stage formed from one or more centrifuges coupled together in parallel. In such an example, the first stage may separate out a first mineral of a relatively heavy specific weight, while the second stage may separate out a second mineral of a lower specific weight than the first mineral. In general, stages need not be formed from identical numbers of centrifuges coupled together in series. As an example, a first stage may be formed from a single centrifuge, while a second stage may be formed from two or more centrifuges coupled together in parallel. In general, references to a centrifuge in the present disclosure are not limited to a single centrifuge and instead encompass a single centrifuge and combinations of multiple centrifuges coupled together in series, parallel, or a combination of series and parallel connections.
As depicted by sound waves 110, centrifuge 108 may be assisted by coupling vibrations or oscillating energy to the fluid in the centrifuge 108. In embodiments, the energy may be in the acoustic range, and the centrifuge may be referred to as an acoustically-assisted centrifuge 108, though it will be understood that in some embodiments the desired energy may oscillate outside the acoustic range. As an example, centrifuge 108 may include one or more acoustic modules that provide acoustic energy 110 into the slurry 106 within the centrifuge 108. The energy 110 may, as an example, represent sub-sonic sound waves. As examples, energy 110 may range from 0.5 Hz to 9 Hz and may vary between 0.5 Hz to 9 Hz over time. As another example, energy 110 may vary between 0.5 Hz and 40 Hz over time.
Acoustic energy 100 may, in various embodiments, include oscillations at multiple frequencies provided simultaneously, sometimes referred to as polyphonic energy. For example, energy 100 may include energy of multiple acoustic frequencies. In some embodiments, different frequencies of energy 100 may create different desired effects. As an example, a first frequency (or set of frequencies) may be tuned to increase mobility of a first mineral, while a second frequency (or set of frequencies) may be tuned to increase mobility of a second mineral or a fluid component of the slurry in the centrifuge 108. As another example, a first frequency (or set of frequencies) may be provided to reduce friction or sticking between particles, while a second frequency (or set of frequencies) may be provided to push minerals of a lower specific weight than desired out of the collection regions.
If desired, acoustic energy 100 may include energy that cancels, minimizes, or reduces undesired ambient energy or energy created by a component of the system. As an example, there may be ambient acoustic energy or acoustic energy created by operation of the centrifuge 108 that slows the rate of stratification in the centrifuge, depending upon the materials of interest and the dimensions of the centrifuge. In such examples, acoustic energy 100 may include energy that cancels such undesirable acoustic energy.
In some embodiments, the frequency or frequencies of energy 110 may be configured to increase fluidization of components of slurry 106. In particular, acoustic energy 110 may help to reduce friction between components of slurry 106, thereby accelerating the separation of materials by specific weight under an acceleration force (such as the centripetal forces generated by centrifuge 108). In various embodiments, energy 110 may increase lubrication in the slurry 106 within the collection regions, may induce super-cavitation within the collection regions, may create one or more standing waves within the collection regions.
If desired, centrifuge 108 may be assisted by something other than oscillating energy of the type depicted by sound waves 110. As an example, in some embodiments, system 100 may include an energy injection module that injects air or fluid into the centrifuge 108 and, in particular, that injects air or fluid into collection regions (such as regions 144 of
Membrane 142 may be formed from materials that facilitate coupling energy from module 140 into collection region 144. As examples, membrane 142 may be formed from Kevlar, graphene, steel, titanium, titanium nitride, rubber, synthetic rubber, metal, plastic, other suitable materials, or combinations of these and other suitable materials. In some embodiments, membrane 142 may be a flexible membrane.
Referring again to
As shown by path 118, excess fluid may be extracted from tailings 114 and reused as in-feed fluid 104, thus cyclically treating the material to progressively extract further minerals.
A cross-section side view of a centrifuge 200 is shown in
As shown in
The circulating slurry 208 may pass over collection regions including collection region 210a. As the slurry 208 passes over the collection regions such as region 210a, the particles having greater specific weights may become trapped within the collection regions. In at least some embodiments, the collection regions 210a may be removably coupled to the sidewalls 202 of the centrifuge 200.
In some embodiments, the centrifuge 200 may include a waste drain 216. In such embodiments, the waste drain 216 may be opened as the slurry 208 may be discharged from the centrifuge 200 when desired. As an example, after minerals having the highest specific weights are concentrated in the collection regions, the remaining slurry 208 may be practically devoid of such minerals and the waste drain 216 may be opened. If desired, the waste drain 216 may be opened while the centrifuge 200 is still spinning (e.g., with or without slowing the centrifuge 208 down from its typical operating speed). After draining waste slurry via the waste drain 216, fresh slurry 208 may be added to the centrifuge 200 for further processing.
A close-up diagram of the energy injection modules 218 and collection regions 210 of
As shown in
In at least some embodiments, the energy injection modules 218a, 218b, etc. may be held against the collection regions 210a, 210b, etc. by springs 220a, 220b, etc. The springs 220a, 220b may provide a counter force to centripetal forces 207, such that the energy injection modules 218a, 218b remain in communication with the collection regions 210a, 201b such that they can couple energy into the collection regions without having to overcome the centripetal forces 207. In at least some embodiments, the springs 220a, 220b may provide a variable spring force, which can be varied in relation to the rotation speed of centrifuge 200 and in relation to the mass of minerals in collection regions 210a, 210b. As an example, the spring force provided by springs 220a, 220b may be increased with increasing rotation speed of the centrifuge 200 and may be increased as minerals having higher specific weights collect in the collection regions. In some embodiments, springs 220a, 220b may be formed from air chambers and the spring force may be increased or decreased by pumping air into or out of the air chambers.
If desired, centrifuge 200 may include sensors that measure the mass of material within collection regions 210a, 210b. As one example, springs 220a, 220b may include sensors that detect how much force is imparted on the springs by the mass within the collection regions (which is subject to centripetal forces 207). The mass of material within collection regions 210a, 210b may be used to determine if the centrifuge is properly balanced, if the stiffness of a spring needs to be increased (e.g., by pumping more air into a suitable air chamber), or if a particular collection region is full or clogged. In at least some embodiments, centrifuge 200 may include control circuitry configured to use information from such sensors to balance the centrifuge (e.g., by selectively disabling one or more energy injection modules to reduce the rate of mass build-up in those modules), to determine when processing of the slurry is complete (e.g., when the desired materials having the greatest specific weights have been suitably concentrated in the collection regions), or for other purposes.
As shown in
At block 402, materials may be obtained for processing in the centrifuge. As discussed herein, the materials may be mine tailings or other material streams that include a mixture of minerals having different specific weights. Additionally, the materials may be ground, screened, or otherwise processed in preparation for separation in the centrifuge. As an example, the materials may be processed to have a suitable particle size.
At block 404, the materials may be mixed with suitable fluid into a slurry. In some embodiments, the slurry may be added to the centrifuge. In at least some embodiments, the centrifuge may be spinning during the addition of slurry. In other embodiments, the centrifuge may be spun up after introduction of slurry. In other embodiments, the slurry may be formed within the centrifuge by separate addition of dry material, such as powder, and fluid.
At block 406, the centrifuge may be spun and modules may be activated to introduce energy into collection regions of the centrifuge. As discussed with respect to
At block 408, waste slurry may be removed or expelled from the centrifuge. In some embodiments, block 408 may be performed after sensors in the centrifuge determine that the collection regions are full, nearly full, filled to a desired capacity, or that the mass of the collection regions has stabilized (e.g., indicating that any higher specific weight minerals in the slurry are already contained within the collection regions and the circulating slurry should be discarded). As noted by arrow 410, additional slurry may be added to the centrifuge after expelling waste slurry in block 408. In other words, blocks 404, 406, and 408 may be repeated as desired. In some embodiments, blocks 404, 406, and 408 may be repeated until sensors in the centrifuge indicate that the collection regions are full or nearly full of material having high specific weight.
At block 412, heavy materials, or materials having a high specific weight, may be extracted from the centrifuge. In some embodiments, block 412 may involve stopping the centrifuge and physically removing and emptying the collection regions, which now contain concentrated high-specific-weight minerals.
Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” “include,” “including,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” The word “coupled,” as generally used herein, refers to two or more elements that may be either directly coupled to each other, or coupled by way of one or more intermediate elements. Likewise, the word “connected,” as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words “herein,” “above,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. Where the context permits, the word “or” in reference to a list of two or more items is intended to cover all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.
Moreover, conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” “for example,” “such as” and the like, unless specifically stated otherwise or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments.
While certain embodiments have been described, these embodiments have been presented by way of example, and are not intended to limit the scope of the disclosure. Indeed, the novel methods, apparatus, and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the methods, apparatus, and systems described herein may be made without departing from the spirit of the disclosure. For example, device components described herein may be deleted, moved, added, subdivided, combined, and/or modified. Each of these device components may be implemented in a variety of different ways. The accompanying claims and their equivalents are intended to cover any such forms or modifications as would fall within the scope and spirit of the disclosure.
The above description is intended to be illustrative and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
This application is a continuation of U.S. patent application Ser. No. 16/374,669, filed Apr. 3, 2019, which claims priority to U.S. Patent Prov. App. 62/652,494, which is titled “SEPARATION OF MINERALS BY SPECIFIC GRAVITY” and was filed on Apr. 4, 2018. The above-recited applications are incorporated herein by reference in their entirety.
Number | Date | Country | |
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62652494 | Apr 2018 | US |
Number | Date | Country | |
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Parent | 16374669 | Apr 2019 | US |
Child | 16552861 | US |