Patent Grant
11642679
This invention relates generally to a method and apparatus for separating valuable material from unwanted material in a mixture, such tailings of a flotation process.
In many industrial processes, flotation is used to separate valuable or desired material from unwanted material. By way of example, in this process a mixture of water, valuable material, unwanted material, chemicals and air is placed into a flotation cell. The chemicals are used to make the desired material hydrophobic and the air is used to carry the material to the surface of the flotation cell. When the hydrophobic material and the air bubbles collide they become attached to each other. The bubble rises to the surface carrying the desired material with it.
The performance of the flotation cell is dependent on the bubble surface area flux in the collection zone of the cell. The bubble surface area flux is dependent on the size of the bubbles and the air injection rate. Controlling the bubble surface area flux has traditionally been very difficult. This is a multivariable control problem and there are no dependable real time feedback mechanisms to use for control.
Froth flotation is a process for selectively separating hydrophobic materials from hydrophilic. The process has been adapted and applied to a wide variety of materials to be separated, and additional collector agents, including surfactants and synthetic compounds have been adopted for various applications. The flotation process is used for the separation of a large range of sulfides, carbonates and oxides prior to further refinement. Phosphates and coal are also upgraded (purified) by flotation technology. Froth flotation commences by comminution (that is, crushing and grinding), which is used to increase the surface area of the ore for subsequent processing. The ore include the desired minerals and other unwanted materials, know a gangue. The process of grinding the ore into a fine power is known as liberation. The fine powder ore is then mixed with water to form pulp slurry. The desired mineral is rendered hydrophobic by the addition of a surfactant or collector chemical. The particular chemical depends on which mineral is being refined. This slurry (more properly called the pulp) of hydrophobic mineral particles and hydrophilic gangue particles is then placed in a flotation column or horizontal pipeline wherein the concentrated mineral is separated from the tailings containing the gangue. To be effective on a given ore slurry, the collectors are chosen based upon their selective wetting of the types of particles to be separated. A good collector will adsorb, physically or chemically, with one of the types of particles. In a flotation circuit for mineral concentration, various flotation reagents are added to a mixture of ore and water (called pulp) in a conditioning tank. The flow rate and tank size are designed to give the minerals enough time to be activated. The conditioner pulp is fed to a bank of rougher cells which remove most of the desired minerals as a concentrate. The rougher pulp passes to a bank of scavenger cells where additional reagents may be added. The scavenger cell froth is usually returned to the rougher cells for additional treatment, but in some cases may be sent to special cleaner cells. The scavenger pulp is usually barren enough to be discarded as tails. More complex flotation circuits have several sets of cleaner and re-cleaner cells, and intermediate re-grinding of pulp or concentrate. A typical slurry processing system is depicted in
There is a need in the industry to provide a better way to separate valuable material from unwanted material, from the discarded tailings.
According to some embodiments, the present invention may take the form of a system having a collection processor configured to receive tailings of a flotation process, the tailings having mineral particles of interest; and at least one collection apparatus located in the collection processor. The collection apparatus may include a collection surface configured with a functionalized polymer having a plurality of molecules with a functional group configured to attract the mineral particles of interest to the collection surface. The flotation process may include one or more scavenger circuits configured to provide one or more scavenger circuit feeds having scavenger tails.
The system features one or more enhanced scavenger circuits having the at least one collection apparatus located in the collection processor and being configured to receive the one or more scavenger circuit feeds and provide enhanced scavenger circuit feeds having a first enhanced scavenger circuit feed with enhanced scavenger tails and a second enhanced scavenger circuit feed with enhanced scavenger concentrate for further processing by the system, based upon the at least one collection apparatus located in the collection processor.
The system according to the present invention may include one or more of the features, as follows:
The one or more scavenger circuits may include a scavenger circuit configured to provide a scavenger circuit feed; and the one or more enhanced scavenger circuits may include an enhanced scavenger circuit configured to receive the scavenger circuit feed and provide the first enhanced scavenger circuit feed as final tails and the second enhanced scavenger circuit feed for further processing by the system.
The flotation process may include a regrind mill configured to receive the second enhanced scavenger circuit feed, and provide a regrind mill feed for further processing by the system.
The flotation process may include a cyclone circuit configured to provide a cyclone U/F circuit feed; and the regrind mill may be configured to receive the cyclone U/F circuit feed, and provide the regrind mill feed for further processing by the system.
The regrind mill may be configured to provide the regrind mill feed to the cyclone circuit for further processing by the cyclone circuit.
The one or more scavenger circuits may include a cleaner scavenger circuit configured to provide a cleaner scavenger circuit feed; and the one or more enhanced scavenger circuits may include an enhanced scavenger circuit configured to receive the cleaner scavenger circuit feed and provide the first enhanced scavenger circuit feed and the second enhanced scavenger circuit feed for further processing by the system.
The flotation process may include a rougher circuit configured to receive the first enhanced scavenger circuit feed and provide a rougher circuit feed for further processing by the system.
The flotation process may include a second scavenger circuit configured to provide a second scavenger circuit feed; and the rougher circuit may be also configured to receive the second scavenger circuit feed and provide the rougher circuit feed for further processing by the system.
The flotation process may include a regrind mill configured to receive the second enhanced scavenger circuit feed, and provide a regrind mill feed for further processing by the system.
The flotation process includes a cyclone circuit configured to provide a cyclone U/F circuit feed; and the regrind mill may be configured to receive the cyclone U/F circuit feed, and provide the regrind mill feed for further processing by the system.
The regrind mill may be configured to provide the regrind mill feed to the cyclone circuit for further processing by the cyclone circuit.
The cyclone circuit may be configured to provide a cyclone O/F circuit feed; and the flotation process may include a cleaner column circuit configured to receive the cyclone O/F circuit feed, and provide a cleaner column circuit feed for further processing by the system.
The cleaner scavenger circuit may be configured to provide a second cleaner scavenger circuit feed; and the cleaner column may be configured to receive the second cleaner scavenger circuit feed and provide the cleaner column feed for further processing by the cleaner scavenger circuit.
The enhanced scavenger circuit may be configured to receive the cleaner scavenger circuit feed and provide the first enhanced scavenger circuit feed and the second enhanced scavenger circuit feed for further processing by the system.
The one or more scavenger circuits may include:
the one or more enhanced scavenger circuits may include:
The flotation process may include a regrind mill configured to receive the corresponding concentrate, and the associate concentrate, and provide a regrind mill feed for further processing by the system.
The flotation process may include a cyclone circuit configured to provide a cyclone circuit feed; and the regrind mill may be configured to receive the cyclone circuit feed, and provide the regrind mill feed for further processing by the system.
The regrind mill may be configured to provide the regrind mill feed to the cyclone circuit for further processing by the cyclone circuit.
The flotation process may include a rougher circuit configured to receive the associated tails and provide a rougher circuit feed for further processing by the system.
The rougher circuit may be configured to receive a scavenger circuit feed from the scavenger circuit and provide the rougher circuit feed for further processing by the system.
The system may include a screen circuit configured to receive the corresponding concentrate and the associate concentrate, and provide screen circuit feeds having a screen circuit U/S feed with a final concentrate and a screen circuit O/S feed for further processing by the process flotation process.
The flotation process may include a regrind mill configured to receive the screen circuit O/S feed, and provide a regrind mill feed for further processing by the system.
The functional group may include an ionizing bond for bonding the mineral particles of interest to the molecules.
The synthetic material may be selected from a group consisting of polyamides, polyesters, polyurethanes, phenol-formaldehyde, urea-formaldehyde, melamine-formaldehyde, polyacetal, polyethylene, polyisobutylene, polyacrylonitrile, poly(vinyl chloride), polystyrene, poly(methyl methacrylates), poly(vinyl acetate), poly(vinylidene chloride), polyisoprene, polybutadiene, polyacrylates, poly(carbonate), phenolic resin, and polydimethylsiloxane.
The functional group may be configured to render the collection area hydrophobic.
The synthetic material may be selected from a group consisting of polystyrene, poly(d,l-lactide), poly(dimethylsiloxane), polypropylene, polyacrylic, polyethylene, hydrophobically-modified ethyl hydroxyethyl cellulose polysiloxanates, alkylsilane and fluoroalkylsilane.
The mineral particles of interest may have one or more hydrophobic molecular segments attached thereon, and the tailings have a plurality of molecules, each collector molecule comprising a first end and a second end, the first end comprising the functional group configured to attach to the mineral particles of interest, the second end comprising a hydrophobic molecular segment.
The synthetic material may include a siloxane derivative.
The synthetic material may comprise polysiloxanates or hydroxyl-terminated polydimethylsiloxanes.
The collection surface may be configured to contact the tailings over a period of time for providing an enriched collection surface in the collection apparatus, containing the mineral particles of interest, and the system may also include a release processor configured to receive the collection apparatus having the enriched collection surface, the release processor further configured to provide a release medium for releasing the mineral particles of interest from the enriched collection surface.
The release medium may include a liquid configured to contact with the enriched collection surface, the liquid having a pH value ranging from 0 to 7.
The release medium may include a liquid configured to contact with the enriched collection surface, and the system may also include an ultrasound source configured to apply ultrasound waves to the enriched collection area for releasing the mineral particles of interest from the enriched collection surface.
A part of the collection surface may be configured to have the molecules attached thereto, wherein the molecules comprise collectors. Another part of the collection surface may be configured to be hydrophobic.
A part of the collection surface is configured to be hydrophobic.
The at least one collection apparatus may include reticulated foam and/or a reticulated foam block providing the three-dimensional open-cell structure.
The three-dimensional open-cell structure reticulated foam an open cell foam.
The open cell foam may be made from a material or materials selected from a group that includes polyester urethanes, polyether urethanes, reinforced urethanes, composites like PVC coated PU, non-urethanes, as well as metal, ceramic, and carbon fiber foams and hard, porous plastics, in order to enhance mechanical durability.
The open cell foam may be coated with polyvinylchloride, and then coated with a compliant, tacky polymer of low surface energy in order to enhance chemical durability.
The open cell foam may be primed with a high energy primer prior to application of a functionalized polymer coating to increase the adhesion of the functionalized polymer coating to the surface of the open cell foam.
The surface of the open cell foam may be chemically or mechanically abraded to provide “grip points” on the surface for retention of the functionalized polymer coating.
The surface of the open cell foam may be coated with a functionalized polymer coating that covalently bonds to the surface to enhance the adhesion between the functionalized polymer coating and the surface.
The surface of the open cell foam may be coated with a functionalized polymer coating in the form of a compliant, tacky polymer of low surface energy and a thickness selected for capturing certain mineral particles and collecting certain particle sizes, including where thin coatings are selected for collecting proportionally smaller particle size fractions and thick coatings are selected for collecting additional large particle size fractions.
The specific surface area may be configured with a specific number of pores per inch that is determined to target a specific size range of mineral particles in the slurry.
The the at least one collection apparatus may include different open cell foams having different specific surface areas that are blended to recover a specific size distribution of mineral particles in the slurry.
According to some embodiments, the present invention may include, or take the form of a method for implementing a system having a collection processor configured to receive tailings of a flotation process, the tailings having mineral particles of interest; and at least one collection apparatus located in the collection processor, the collection apparatus having a collection surface configured with a functionalized polymer comprising a plurality of molecules having a functional group configured to attract the mineral particles of interest to the collection surface, the flotation process having one or more scavenger circuits configured to provide one or more scavenger circuit feeds having scavenger tails,
wherein the method comprises configuring the system with one or more enhanced scavenger circuits having the at least one collection apparatus located in the collection processor and configured to receive the one or more scavenger circuit feeds and provide enhanced scavenger circuit feeds having a first enhanced scavenger circuit feed with enhanced scavenger tails and a second enhanced scavenger circuit feed with enhanced scavenger concentrate for further processing by the system, based upon the at least one collection apparatus located in the collection processor.
The method may include steps for implementing one or more of the additional features set forth herein.
Referring now to the drawing, which are not necessarily drawn to scale, the foregoing and other features and advantages of the present invention will be more fully understood from the following detailed description of illustrative embodiments, taken in conjunction with the accompanying drawing in which like elements are numbered alike:
This application builds and improves on technology disclosed in the aforementioned PCT application no. PCT/US12/39655, which corresponds to U.S. patent application Ser. No. 14/119,013, filed 23 Mar. 2015, as well as PCT application no. PCT/US17/37322, which corresponds to U.S. patent application Ser. No. 15/401,755, filed 9 Jan. 2017, which are all incorporated by reference in their entirety.
b form part of the aforementioned PCT application no. PCT/US12/39655,
In summary, the present invention sets forth an improvement to the use of the assignee's polymer separation technology in a scavenging application to concentrate valuable mineral particles from a stream that would otherwise be discarded or recirculated.
By way of example,
In this process shown in
The new technology according to the present invention is able to selectively concentrate value mineral particles from tailings streams in mineral processing plants which would otherwise be unrecoverable due to issues with particle size, mineral associations, mineral liberation or mineral surface exposure. Details of this application of the scavenger technology have been disclosed previously (See the aforementioned PCT application no. PCT/US12/39655, set forth in the family of the assignee's cases herein). A key process step in many beneficiation processes is the regrind stage (
Regrinding steps may also be used for the products of scavenging separation stages (
In the case of the new tailings scavenging technology, examples of embodiments/applications according to the present invention are shown in
In particular, according to some embodiments of the present invention, the flotation circuit in
In
However, one negative aspect of the flotation circuit shown in
In view of this, some embodiments of the present invention may be geared towards addressing this issue, e.g., by employing additional classification steps for the ESC-produced concentrates as shown in
In particular, according to some embodiments of the present invention, the flotation circuit shown in
Many valuable minerals show preferential deportment to finer size classes relative to common gangue minerals (often silicates) so it is reasonable to expect a significant amount of the valuable minerals in the assignee's circuit feeds (
Consistent with that disclosed in the aforementioned PCT application no. PCT/US12/39655, the ESC1 and ESC2 according to the present invention may be implement using one or more of the combinations of technology disclosed in relation to
By way of example, tailings from a flotation process can be processed in a tailings pond or in a location between the end of the flotation process and the tailings pond. According to some embodiments of the present invention, a method or technique is provided to recover a valuable material or mineral particle of interest in, or that form part of, the tailings, using collection apparatus that may be functionalized with a synthetic material comprising a plurality of molecules having a functional group configured to attract the mineral particles of interest to the surface of the collection apparatus. The method or technique includes causing the collection apparatus to contact with the tailings having the mineral particles of interest, including the tailings from a flotation process. Numerous techniques or ways are set forth herein for causing the collection apparatus to contact with the tailings.
According to some embodiments of the present invention, the functional group may include an ionizing bond for bonding the mineral particles to the molecules. According to some embodiments of the present invention, the functional group may render the collection area or surface hydrophobic in order to attract hydrophobic mineral particles of interest. In the specification, the terms “functionalized synthetic material”, “synthetic material” and “functionalized polymer” are used interchangeably. The terms “valuable material”, “valuable mineral” and “mineral particles of interest” are also used interchangeably. The term “polymer” means a large molecule made of many units of the same or similar structure linked together.
In the embodiment as shown in
In the embodiment as shown in
In the embodiment as shown in
In the embodiment as shown in
By way of example, the functionalized polymer 20, 30 may comprise functionalized polymer coated collection areas or surfaces as shown in
By way of example, the functionalized polymer 30 (
In the embodiment as shown in
In the embodiment as shown in
In the embodiment as shown in
By way of example, the conveyor belt 120 (
The collection area 323 of the collection plate 320 can take many different forms. For example, the collection area 323 on one or both of sides of the collection plate 323 can be a smooth surface, as shown in
By way of example, each of the collection areas 123, 223 and 323 (
By way of example, the fiber-like structures 705 (
In a different embodiment of the present invention, the fiber 401′ (
The surfaces and edges around the openings or surface structures 701, 702, 703, 704 (
In a different embodiment of the present invention, the surface portion 403′ can be made of a polymer having a plurality of molecules 79 that render the surface portion 403′ (and thus the collection areas 123, 223 and 323 of
The treatment of plain surface 706 (
It should be understood that, when the collection area or surface 123 of the conveyor belt 120 (
In different embodiments of the present invention, the functionalized synthetic material can be used to provide those particular molecules on beads or bubbles, or to make the beads or bubbles (see
The releasing of the mineral particles from the synthetic beads can be similar to the releasing of the mineral particles from the collection plate, conveyor belt or the filter. For example, after the synthetic beads 170 in the collection area 223 or 323 or in the sack 320 (
By way of example,
The first processor 612 may take the form of a first chamber, tank, cell or column that contains an attachment rich environment generally indicated as 616. The first chamber, tank or column 612 may be configured to receive via piping 613 the mixture or tailings 611 in the form of fluid (e.g., water), the valuable material and the unwanted material in the attachment rich environment 616, e.g., which has a high pH, conducive to attachment of the valuable material. The second processor 614 may take the form of a second chamber, tank, cell or column that contains a release rich environment generally indicated as 618. The second chamber, tank, cell or column 614 may be configured to receive via piping 615, e.g., water 622 in the release rich environment 618, e.g., which may have a low pH or receive ultrasonic waves conducive to release of the valuable material. Attachment rich environments like that forming part of element environment 616 conducive to the attachment of a valuable material of interest and release rich environments like that forming part of environment 618 conducive to the release of the valuable material of interest are known in the art, and the scope of the invention is not intended to be limited to any particular type or kind thereof either now known or later developed in the future. Moreover, a person skilled in the art would be able to formulate an attachment rich environment like environment 616 and a corresponding release rich environment like environment 618 based on the separation technology disclosed herein for any particular valuable mineral of interest, e.g., copper, forming part of any particular mixture or tailings.
In operation, the first processor 612 may be configured to receive the mixture or tailings 611 of water, valuable material and unwanted material and the functionalized polymer coated member that is configured to attach to the valuable material in the attachment rich environment 616. In
In
The first processor 612 may also be configured to provide at least one enriched impeller blade having the valuable material attached thereto, after passing through the attachment rich environment 616. In
The second processor 614 may be configured to receive via the piping 615 the fluid 622 (e.g. water) and the enriched functionalized polymer coated member to release the valuable material in the release rich environment 618. In
The second processor 614 may also be configured to provide the valuable material that is released from the enriched functionalized polymer coated member into the release rich environment 618. For example, in
By way of example,
The first processor 702 may take the form of a first chamber, tank, cell or column that contains an attachment rich environment generally indicated as 706. The first chamber, tank or column 702 may be configured to receive the mixture or tailings 701 in the form of fluid (e.g., water), the valuable material and the unwanted material in the attachment rich environment 706, e.g., which has a high pH, conducive to attachment of the valuable material. The second processor 704 may take the form of a second chamber, tank, cell or column that contains a release rich environment generally indicated as 708. The second chamber, tank, cell or column 704 may be configured to receive, e.g., water 722 in the release rich environment 708, e.g., which may have a low pH or receive ultrasonic waves conducive to release of the valuable material. Consistent with that stated above, attachment rich environments like that forming part of element environment 706 conducive to the attachment of a valuable material of interest and release rich environments like that forming part of environment 708 conducive to the release of the valuable material of interest are known in the art, and the scope of the invention is not intended to be limited to any particular type or kind thereof either now known or later developed in the future. Moreover, a person skilled in the art would be able to formulate an attachment rich environment like environment 106 and a corresponding release rich environment like environment 708 based on the separation technology disclosed herein for any particular valuable mineral of interest, e.g., copper, forming part of any particular mixture or tailings.
In operation, the first processor 702 may be configured to receive the mixture or tailings 701 of water, valuable material and unwanted material and the functionalized polymer coated conveyor belt 720 that is configured to attach to the valuable material in the attachment rich environment 706. In
The first processor 702 may also be configured to provide drainage from piping 741 of, e.g., processed tailings 742 as shown in
The first processor 702 may also be configured to provide an enriched functionalized polymer coated conveyor belt having the valuable material attached thereto, after passing through the attachment rich environment 706. In
The second processor 704 may be configured to receive the fluid 722 (e.g. water) and the portion 720a of the enriched functionalized polymer coated conveyor belt 720 to release the valuable material in the release rich environment 708.
The second processor 704 may also be configured to provide the valuable material that is released from the enriched functionalized polymer coated member into the release rich environment 708. For example, in
In
By way of example,
The first processor 802 may take the form of a first chamber, tank, cell or column that contains an attachment rich environment generally indicated as 806. The first chamber, tank or column 802 may be configured to receive the mixture or tailings 801 in the form of fluid (e.g., water), the valuable material and the unwanted material in the attachment rich environment 806, e.g., which has a high pH, conducive to attachment of the valuable material. The second processor 804 may take the form of a second chamber, tank, cell or column that contains a release rich environment generally indicated as 808. The second chamber, tank, cell or column 804 may be configured to receive, e.g., water 822 in the release rich environment 808, e.g., which may have a low pH or receive ultrasonic waves conducive to release of the valuable material. Consistent with that stated above, attachment rich environments like that forming part of element environment 806 conducive to the attachment of a valuable material of interest and release rich environments like that forming part of environment 808 conducive to the release of the valuable material of interest are known in the art, and the scope of the invention is not intended to be limited to any particular type or kind thereof either now known or later developed in the future. Moreover, a person skilled in the art would be able to formulate an attachment rich environment like environment 806 and a corresponding release rich environment like environment 808 based on the separation technology disclosed herein for any particular valuable mineral of interest, e.g., copper, forming part of any particular mixture or tailings.
In operation, the first processor 802 may be configured to receive the mixture or tailings 101 of water, valuable material and unwanted material and the functionalized polymer coated collection filter 820 that is configured to attach to the valuable material in the attachment rich environment 806. In
The first processor 802 may also be configured to provide drainage from piping 841 of, e.g., processed tailings 842 as shown in
The first processor 802 may also be configured to provide an enriched functionalized polymer coated collection filter having the valuable material attached thereto, after soaking in the attachment rich environment. In
The second processor 804 may be configured to receive the fluid 822 (e.g. water) and the enriched functionalized polymer coated collection filter 820 to release the valuable material in the release rich environment 808.
The second processor 804 may also be configured to provide the valuable material that is released from the enriched functionalized polymer coated collection filter 220 into the release rich environment 808. For example, in
The first processor 802′ may also be configured with piping 880 and pumping 880 to recirculate the tailings 842 back into the first processor 802′. The scope of the invention is also intended to include the second processor 804′ being configured with corresponding piping and pumping to recirculate the concentrate 862 back into the second processor 804′. Similar recirculation techniques may be implemented for the embodiments disclosed in relation to
The scope of the invention is not intended to be limited to the type or kind of batch process being implemented. For example, embodiments are envisioned in which the batch process may include the first and second processors 802, 804 being configured to process the enriched functionalized polymer coated collection filter 820 in relation to one type or kind of valuable material, and the first and second processors 802′,804′ being configured to process the enriched functionalized polymer coated collection filter 820 in relation to either the same type or kind of valuable material, or a different type or kind of valuable material. Moreover, the scope of the invention is intended to include batch processes both now known and later developed in the future.
The term “polymer” in this disclosure means a large molecule made of many units of the same or similar structure linked together. In some embodiments of the present invention, the polymer surface on a filter has a plurality of molecules 73 (
In some embodiments of the present invention, at least the surface of a filter surface is functionalized so that the surface is hydrophobic. It is possible to functionalize a polymer surface to have a plurality of molecules 79 (
In chemistry, hydrophobicity is the physical property of a molecule (known as a hydrophobe) that is repelled from a mass of water. Hydrophobic molecules tend to be non-polar and, thus, prefer other neutral molecules and non-polar solvents. Hydrophobic molecules in water often cluster together. According to thermodynamics, matter seeks to be in a low-energy state, and bonding reduces chemical energy. Water is electrically polarized, and is able to form hydrogen bonds internally, which gives it many of its unique physical properties. But, since hydrophobes are not electrically polarized, and because they are unable to form hydrogen bonds, water repels hydrophobes, in favor of bonding with itself. It is this effect that causes the hydrophobic interaction.
The hydrophobic effect is the observed tendency of nonpolar substances to aggregate in aqueous solution and exclude water molecules. It can be observed as the segregation and apparent repulsion between water and non-polar substances. The hydrophobic interaction is mostly an entropic effect originating from the disruption of highly dynamic hydrogen bonds between molecules of liquid water by the non-polar solute. A hydrocarbon chain or a similar non-polar region or a big molecule is incapable of forming hydrogen bonds with water. The introduction of such a non-hydrogen bonding surface into water causes disruption of the hydrogen bonding network between water molecules. The hydrogen bonds are reoriented tangential to such a surface to minimize disruption of the hydrogen bonded 3D network of water molecules and thus leads to a structured water “cage” around the nonpolar surface. The water molecules that form the “cage” (or solvation shell) have restricted mobilities. For example, in the case of larger non-polar molecules the reorientational and translational motion of the water molecules in the solvation shell may be restricted by a factor of two to four. Generally, this leads to significant losses in translational and rotational entropy of water molecules and makes the process unfavorable in terms of free energy of the system. By aggregating together, nonpolar molecules reduce the surface area exposed to water and minimize their disruptive effect.
The desired mineral is rendered hydrophobic by the addition of a surfactant or collector chemical. To be effective on tailings, the collectors are chosen based upon their selective wetting of the types of particles to be separated. A good collector will adsorb, physically or chemically, with one of the types of particles.
Collectors either chemically bond (chemisorption) on a hydrophobic mineral surface, or adsorb onto the surface in the case of, for example, coal flotation through physisorption. Collectors increase the hydrophobicity of the surface, increasing the separability of the hydrophobic and hydrophilic particles. The hydrophobic particles of interest, according to the present invention, are depicted as particles 71′,72′ in
It should be noted that the mineral particles in the tailings can be relatively large as compared to the mineral particles recovered in the flotation process. Some mineral particles may be larger than 200μm, for example. It is likely that a large mineral particle requires more bonding forces so that it can be attached to a functionalized surface. As shown in
The scope of the invention is described in relation to mineral separation, including the separation of copper from ore.
By way of example, applications are envisioned to include rougher, scavenger, cleaner and Rougher/scavenger separation cells in the production stream, replacing the traditional flotation machines.
Tailings scavenger cells are used to scavenge the unrecovered minerals from a tailings stream.
Tailings cleaning cell is used to clean unwanted material from the tailings stream before it is sent to the disposal pond.
Tailings reclamation machine that is placed in the tailings pond to recover valuable mineral that has been sent to the tailings pond.
It should be understood that the synthetic beads according to the present invention, whether functionalized to have a collector or functionalized to be hydrophobic, are also configured for use in oilsands separation—to separate bitumen from sand and water in the recovery of bitumen in an oilsands mining operation. Likewise, the functionalized filters and membranes, according to some embodiments of the present invention, are also configured for oilsands separation.
According to some embodiments of the present invention, the surface of a synthetic bead can be functionalized to have a collector molecule. The collector has a functional group with an ion capable of forming a chemical bond with a mineral particle. A mineral particle associated with one or more collector molecules is referred to as a wetted mineral particle. According to some embodiments of the present invention, the synthetic bead can be functionalized to be hydrophobic in order to collect one or more wetted mineral particles.
Other types or kinds of valuable material or minerals of interest, include gold, molybdenum, etc.
However, the scope of the invention is intended to include other types or kinds of applications either now known or later developed in the future.
According to a different embodiment of the present invention, the synthetic bead can be a porous block or take the form of a sponge or foam with multiple segregated gas filled chambers. This application expands upon and develops out in further detail various inventions related to the use of engineered collection media in the form of foam, Styrofoam, etc. in relation to
By way of example, the synthetic bead can be a porous block or take the form of a sponge or foam with multiple segregated gas filled chamber. According to some embodiments of the present invention, the foam or sponge can take the form of a filter, a membrane or a conveyor belt as described in PCT application no. PCT/US12/39534, entitled “Mineral separation using functionalized membranes;” filed 21 May 2012, which is hereby incorporated by reference in its entirety. Therefore, the synthetic beads described herein are generalized as engineered collection media. Likewise, a porous material, foam or sponge may be generalized as a material with three-dimensional open-cellular structure, an open-cell foam or reticulated foam, which can be made from soft polymers, hard plastics, ceramics, carbon fibers, glass and/or metals, and may include a hydrophobic chemical having molecules to attract and attach mineral particles to the surfaces of the engineered collection media.
Open-cell foam or reticulated foam offers an advantage over non-open cell materials by having higher surface area to volume ratio. Applying a functionalized polymer coating that promotes attachment of mineral to the foam “network” enables higher mineral recovery rates and also improves recovery of less liberated mineral than conventional process. For example, the open cells in an engineered foam block allow passage of fluid and particles smaller than the cell size but captures mineral particles that come in contact with the functionalized polymer coating on the open cells. This also allows the selection of cell size dependent upon slurry properties and application.
According to some embodiments of the present invention, the engineered collection media take the form of an open-cell foam/structure in a rectangular block or a cubic shape 70a as illustrated in
According to some embodiments of the present invention, the engineered collection media may take the form of a filter 70b with a three-dimensional open-cell structure as shown in
According some embodiments of the present invention, the engineered collection media may take the form of a membrane 70c, a section of which is shown in
According some embodiments of the present invention, the engineered collection media may take the form of a membrane 70d, a section of which is shown in
In various embodiments of the present invention, the engineered collection media as shown in
In some embodiments of the present invention, the open-cell structure or foam may include a coating attached thereto to provide a plurality of molecules to attract mineral particles, the coating including a hydrophobic chemical selected from a group consisting of polysiloxanates, poly(dimethylsiloxane) and fluoroalkylsilane, or what are commonly known as pressure sensitive adhesives with low surface energy.
In some embodiments of the present invention, the solid phase body may be made from a material selected from polyurethane, polyester urethane, polyether urethane, reinforced urethanes, PVC coated PV, silicone, polychloroprene, polyisocyanurate, polystyrene, polyolefin, polyvinylchloride, epoxy, latex, fluoropolymer, polypropylene, phenolic, EPDM, and nitrile.
In some embodiments of the present invention, the solid phase body may including a coating or layer, e.g., that may be modified with tackifiers, plasticizers, crosslinking agents, chain transfer agents, chain extenders, adhesion promoters, aryl or alky copolymers, fluorinated copolymers, hexamethyldisilazane, silica or hydrophobic silica.
In some embodiments of the present invention, the solid phase body may include a coating or layer, e.g., made of a material selected from acrylics, butyl rubber, ethylene vinyl acetate, natural rubber, nitriles; styrene block copolymers with ethylene, propylene, and isoprene; polyurethanes, and polyvinyl ethers.
In some embodiments of the present invention, an adhesion agent may be provided between the solid phase body and the coating so as to promote adhesion between the solid phase body and the coating.
In some embodiments of the present invention, the solid phase body may be made of plastic, ceramic, carbon fiber or metal.
In some embodiments of the present invention, the three-dimensional open-cell structure may include pores ranging from 10-200 pores per inch.
In some embodiments of the present inventions, the engineered collection media may be encased in a cage structure that allows a mineral-containing slurry to pass through the cage structure so as to facilitate the contact between the mineral particles in slurry and the engineered collection media.
In some embodiments of the present invention, the cage structures or the filters carrying mineral particles may be removed from the processor so that they can be stripped of the mineral particles, cleaned and reused.
Surface area is an important property in the mineral recovery process because it defines the amount of mass that can be captured and recovered. High surface area to volume ratios allows higher recovery per unit volume of media added to a cell. As illustrated in
The coated foam may be cut in a variety of shapes and forms. For example, a polymer coated foam belt can be moved through the slurry to collect the desired minerals and then cleaned to remove the collected desired minerals. The cleaned foam belt can be reintroduced into the slurry. Strips, blocks, and/or sheets of coated foam of varying size can also be used where they are randomly mixed along with the slurry in a mixing cell. The thickness and cell size of a foam can be dimensioned to be used as a cartridge-like filter which can be removed, cleaned of recovered mineral, and reused.
As mentioned earlier, the open cell or reticulated foam, when coated or soaked with hydrophobic chemical, offers an advantage over other media shapes such as sphere by having higher surface area to volume ratio. Surface area is an important property in the mineral recovery process because it defines the amount of mass that can be captured and recovered. High surface area to volume ratios allows higher recovery per unit volume of media added to a cell.
The open cell or reticulated foam provides functionalized three dimensional open network structures having high surface area with extensive interior surfaces and tortuous paths protected from abrasion and premature release of attached mineral particles. This provides for enhanced collection and increased functional durability. Spherical shaped recovery media, such as beads, and also of belts, and filters, is poor surface area to volume ratio—these media do not provide high surface area for maximum collection of mineral. Furthermore, certain media such as beads, belts and filters may be subject to rapid degradation of functionality.
Applying a functionalized polymer coating that promotes attachment of mineral to the foam “network” enables higher recovery rates and improved recovery of less liberated mineral when compared to the conventional process. This foam is open cell so it allows passage of fluid and unattracted particles smaller than the cell size but captures mineral bearing particles the come in contact with the functionalized polymer coating. Selection of cell size is dependent upon slurry properties and application.
A three-dimensional open cellular structure optimized to provide a compliant, tacky surface of low energy enhances collection of hydrophobic or hydrophobized mineral particles ranging widely in particle size. This structure may include, or take the form of, open-cell foam coated with a compliant, tacky polymer of low surface energy. The foam may include, or take the form of, reticulated polyurethane or another appropriate open-cell foam material such as silicone, polychloroprene, polyisocyanurate, polystyrene, polyolefin, polyvinylchloride, epoxy, latex, fluoropolymer, phenolic, EPDM, nitrile, composite foams and such. The coating may be a polysiloxane derivative such as polydimethylsiloxane and may be modified with tackifiers, plasticizers, crosslinking agents, chain transfer agents, chain extenders, adhesion promoters, aryl or alky copolymers, fluorinated copolymers, hydrophobizing agents such as hexamethyldisilazane, and/or inorganic particles such as silica or hydrophobic silica. Alternatively, the coating may include, or take the form of, materials typically known as pressure sensitive adhesives, e.g. acrylics, butyl rubber, ethylene vinyl acetate, natural rubber, nitriles; styrene block copolymers with ethylene, propylene, and isoprene; polyurethanes, and polyvinyl ethers as long as they are formulated to be compliant and tacky with low surface energy.
The three-dimensional open cellular structure may be coated with a primer or other adhesion agent to promote adhesion of the outer collection coating to the underlying structure.
In addition to soft polymeric foams, other three-dimensional open cellular structures such as hard plastics, ceramics, carbon fiber, and metals may be used. Examples include Incofoam®, Duocel®, metal and ceramic foams produced by American Elements®, and porous hard plastics such as polypropylene honeycombs and such. These structures must be similarly optimized to provide a compliant, tacky surface of low energy by coating as above.
The three-dimensional, open cellular structures above may be coated or may be directly reacted to form a compliant, tacky surface of low energy.
The three-dimensional, open cellular structure may itself form a compliant, tacky surface of low energy by, for example, forming such a structure directly from the coating polymers as described above. This is accomplished through methods of forming open-cell polymeric foams known to the art.
The structure may be in the form of sheets, cubes, spheres, or other shapes as well as densities (described by pores per inch and pore size distribution), and levels of tortuosity that optimize surface access, surface area, mineral attachment/detachment kinetics, and durability. These structures may be additionally optimized to target certain mineral particle size ranges, with denser structures acquiring smaller particle sizes. In general, cellular densities may range from 10-200 pores per inch, more preferably 30-90 pores per inch, and most preferably 30-60 pores per inch.
The specific shape or form of the structure may be selected for optimum performance for a specific application. For example, the structure (coated foam for example) may be cut in a variety of shapes and forms. For example, a polymer coated foam belt could be moved through the slurry removing the desired mineral whereby it is cleaned and reintroduced into the slurry. Strips, blocks, and/or sheets of coated foam of varying size could also be used where they are randomly mixed along with the slurry in a mixing cell. Alternatively, a conveyor structure may be formed where the foam is encased in a cage structure that allows a mineral-containing slurry to pass through the cage structure to be introduced to the underlying foam structure where the mineral can react with the foam and thereafter be further processed in accordance with the present invention. The thickness and cell size could be changed to a form cartridge like filter whereby the filter is removed, cleaned of recovered mineral, and reused.
There are numerous characteristics of the foam that may be important and should also be considered, as follows:
Mechanical durability: Ideally, the foam will be durable in the mineral separation process. For example, a life of over 30,000 cycles in a plant system would be beneficial. As discussed above, there are numerous foam structures that can provide the desired durability, including polyester urethanes, polyether urethanes, reinforced urethanes, more durable shapes (spheres & cylinders), composites like PVC coated PU, and non-urethanes. Other potential mechanically durable foam candidate includes metal, ceramic, and carbon fiber foams and hard, porous plastics.
Chemical durability: The mineral separation process can involve a high pH environment (up to 12.5), aqueous, and abrasive. Urethanes are subject to hydrolytic degradation, especially at pH extremes. While the functionalized polymer coating provides protection for the underlying foam, ideally, the foam carrier system is resistant to the chemical environment in the event that it is exposed.
Adhesion to the coating: If the foam surface energy is too low, adhesion of the functionalized polymer coating to the foam will be very difficult and it could abrade off. However, as discussed above, a low surface energy foam may be primed with a high energy primer prior to application of the functionalized polymer coating to improve adhesion of the coating to the foam carrier. Alternatively, the surface of the foam carrier may be chemically abraded to provide “grip points” on the surface for retention of the polymer coating, or a higher surface energy foam material may be utilized. Also, the functionalized polymer coating may be modified to improve its adherence to a lower surface energy foam. Alternatively, the functionalized polymer coating could be made to covalently bond to the foam.
Surface area: Higher surface area provides more sites for the mineral to bond to the functionalized polymer coating carried by the foam substrate. There is a tradeoff between larger surface area (for example using small pore cell foam) and ability of the coated foam structure to capture mineral while allowing gangue material to pass through and not be capture, for example due to a small cell size that would effectively entrap gangue material. The foam size is selected to optimize capture of the desired mineral and minimize mechanical entrainment of undesired gangue material.
Cell size distribution: Cell diameter needs to be large enough to allow gangue and mineral to be removed but small enough to provide high surface area. There should be an optimal cell diameter distribution for the capture and removal of specific mineral particle sizes.
Tortuosity: Cells that are perfectly straight cylinders have very low tortuosity. Cells that twist and turn throughout the foam have “tortuous paths” and yield foam of high tortuosity. The degree of tortuosity may be selected to optimize the potential interaction of a mineral particle with a coated section of the foam substrate, while not be too tortuous that undesirable gangue material in entrapped by the foam substrate.
Functionalized foam: It may be possible to covalently bond functional chemical groups to the foam surface. This could include covalently bonding the functionalized polymer coating to the foam or bonding small molecules to functional groups on the surface of the foam, thereby making the mineral-adhering functionality more durable.
The pore size (pores per inch (PPI)) of the foam is an important characteristic which can be leveraged to improved mineral recovery and/or target a specific size range of mineral. As the PPI increases the specific surface area (SSA) of the foam also increases. A high SSA presented to the process increases the probability of particle contact which results in a decrease in required residence time. This in turn, can lead to smaller size reactors. At the same time, higher PPI foam acts as a filter due to the smaller pore size and allows only particles smaller than the pores to enter into its core. This enables the ability to target, for example, mineral fines over coarse particles or opens the possibility of blending a combination of different PPI foam to optimize recovery performance across a specific size distribution.
It should be further appreciated that any of the features, characteristics, alternatives or modifications described regarding a particular embodiment herein may also be applied, used, or incorporated with any other embodiment described herein. In addition, it is contemplated that, while the embodiments described herein are useful for homogeneous flows, the embodiments described herein can also be used for dispersive flows having dispersive properties (e.g., stratified flow). Although the invention has been described and illustrated with respect to exemplary embodiments thereof, the foregoing and various other additions and omissions may be made therein and thereto without departing from the spirit and scope of the present invention.
The present application claims the benefit of U.S. Provisional Patent Application No. 62/464,505, filed 28 Feb. 2017, which is incorporated by reference herein in its entirety. This application is also related to a family of nine PCT applications, which were all concurrently filed on 25 May 2012, as follows: PCT application no. PCT/US12/39528, entitled “Flotation separation using lightweight synthetic bubbles and beads;”PCT application no. PCT/US12/39524, entitled “Mineral separation using functionalized polymer membranes;”PCT application no. PCT/US12/39540, entitled “Mineral separation using sized, weighted and magnetized beads;”PCT application no. PCT/US12/39576, entitled “Synthetic bubbles/beads functionalized with molecules for attracting or attaching to mineral particles of interest,” which corresponds to U.S. Pat. No. 9,352,335;PCT application no. PCT/US12/39591, entitled “Method and system for releasing mineral from synthetic bubbles and beads;”PCT application no. PCT/US/39596, entitled “Synthetic bubbles and beads having hydrophobic surface;”PCT application no. PCT/US/39631, entitled “Mineral separation using functionalized filters and membranes,” which corresponds to U.S. Pat. No. 9,302,270;”PCT application no. PCT/US12/39655, entitled “Mineral recovery in tailings using functionalized polymers;” andPCT application no. PCT/US12/39658, entitled “Techniques for transporting synthetic beads or bubbles In a flotation cell or column,” all of which are incorporated by reference in their entirety. This application is also related to other applications, as follows: PCT application no. PCT/US2013/042202, filed 22 May 2013, entitled “Charged engineered polymer beads/bubbles functionalized with molecules for attracting and attaching to mineral particles of interest for flotation separation,” which claims the benefit of U.S. Provisional Patent Application No. 61/650,210, filed 22 May 2012;PCT/US2014/037823, filed 13 May 2014, entitled “Polymer surfaces having a siloxane functional group,” which claims benefit to U.S. Provisional Patent Application No. 61/822,679, filed 13 May 2013, as well as U.S. patent application Ser. No. 14/118,984, filed 27 Jan. 2014, and is a continuation-in-part to PCT application no. PCT/US12/39631 (712-2.385//CCS-0092), filed 25 May 2012;PCT application no. PCT/US13/28303, filed 28 Feb. 2013, entitled “Method and system for flotation separation in a magnetically controllable and steerable foam;”PCT application no. PCT/US16/57334, filed 17 Oct. 2016, entitled “Opportunities for recovery augmentation process as applied to molybdenum production;” andPCT application no. PCT/US16/37322, filed 17 Oct. 2016, entitled “Mineral beneficiation utilizing engineered materials for mineral separation and coarse particle recovery,”PCT application no. PCT/US17/37322, filed 9 Jan. 2017, entitled “Recovery media for mineral processing, using open cell or reticulated foam having 3-dimensional functionalized open-network structure for selective separation of mineral particles in an aqueous system,” which are all also hereby incorporated by reference in its entirety. All of the aforementioned patent applications are assigned to and owned by the assignee of the instant application.
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| WO2018/160628 | 9/7/2018 | WO | A |
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