PRIORITY STATEMENT

[0001] This application claims the benefit of priority under 35 U.S.C. § 119(e) from United States Provisional Patent Application No. 61/486,545, which was filed in the United States Patent and Trademark Office on May 16, 2011, the contents of which are hereby incorporated, in their entirety, by reference.

BACKGROUND

[0002] There are several historical, or conventional, techniques and processes for dealing with the various aspects of separating magnetic particles from undesirable contaminants, including petroleum hydrocarbons; other organic contaminants including dioxins and PCBs; non-magnetic salts tightly bound in various crystalline formations; and other undesirable compounds. As particle sizes decrease to the sub- 100 μηι range, techniques focus on thermal processes and chemical extractions.

[0003] Many different fine particle material streams contain a significant quantity of magnetic particles, bound with non-magnetic materials in a variety of physio-chemical configurations. Often, these material streams have jelly-like, "spongy" characteristics. Materials with these characteristics have an enormous surface area per unit of volume, which entraps and binds together small particles into the material composite.

[0004] In some cases, inverse crystalline structures of magnetic and non-magnetic metals, oxides, and salts result in interlocking structures on a microscopic level. Although such interlocking structures are not chemically bound (or are only weakly bound), the enormous surface area of these fine streams results in extremely highly coefficients of friction and surface tension, making it extremely difficult to separate the various components of this matrix using traditional separation techniques.

[0005] Due to the difficulty of extracting specific elements and compounds, these valuable fine particle material streams are typically used in low -value applications, or disposed of as industrial waste. Examples of these waste streams include: ° Steel mill wastewater treatment sludge;

° Steel plant mill scale ;

° Bauxite residue;

° Mine tailings;

° Harbor, marine, and pond sediments; and

° Wastewater sludge.

[0006] These materials contain various combinations of iron, iron compounds, titanium, rare earth metals and organic contaminants. For most of the above material streams, neither thermal nor chemical extraction processes are economically viable, as the value of the energy or chemicals used during extraction exceeds the value of the underlying materials that can be recovered. This economic reality has resulted in the accumulation of hundreds of millions of tons of these materials in both temporary and permanent storage facilities worldwide.

BRIEF SUMMARY

[0007] The presently disclosed methods use a physical process by which magnetic particles can be separated from, for example, organic compounds and inorganic salts in which they are contained. Once this process has been completed, the magnetic particles are thereafter separated for recovery and reuse. The disclosed methods, when executed in accord with the disclosed steps and apparatus, are capable of separating up to 99% of the magnetic particles from the undesirable waste materials. In most of these materials, the magnetic particles are incorporated as a fine powder that, when separated, can be utilized in a number of industries, including as a replacement for ore feedstocks, industrial coatings, pigments, and nano- particle applications such as electrostatic films and exotic medical compounds.

[0008] Methods of separating fine magnetic particles from composite material fines according to the invention include the steps of combining composite fine solids with a carrier liquid to form a mixed stream, the fine solids including both magnetic and non-magnetic particles; injecting the mixed stream into a processing chamber; subjecting the mixed stream to a plurality of secondary high-pressure streams within the processing chamber, wherein the high-pressure streams have a composition, pressure and orientation sufficient to disrupt the fine solids and separate the magnetic and non-magnetic particles; subjecting the disrupted fine solids to a magnetic field, wherein the magnetic field is oriented in a direction generally perpendicular to a flow direction of the disrupted fine solids and wherein the magnetic field is sufficient to accumulate a portion of the magnetic particles from the depleted mixed stream on a magnetic recovery surface; and recovering the accumulated magnetic particles.

[0009] These methods can, in turn, be practiced with a number of variations including, for example, utilizing mixed stream(s) characterized by a solids content of no more than 35%, maintaining the mixed stream within a target operating temperature range of 5° C. to 80° C. although operation within + 10° C. or + 5° C. of ambient or even at ambient would tend to reduce associated energy costs and would generally be preferred over operations that depart significantly from the ambient temperature. As will be appreciated by those skilled in the art, the carrier liquid can include one or more solvents selected from, for example, benzene, toluene and deuterium-containing compounds as well as mixtures and derivatives thereof. Other variations of the methods include utilizing injection pressures for the mixed stream and the secondary high- pressure streams of from, for example, 13.8 MPa to 138 MPa, although some applications may utilize pressures above 138 MPa, and a magnetic field strength of 1000 to 5000 gauss, more typically 2500 to 4500 gauss.

[0010] These methods can also be implemented in multi-stage configurations including, for example, embodiments in which the depleted mixed stream is subjected to a second plurality of secondary high-pressure streams within a second processing chamber, wherein the high-pressure streams have a composition, pressure and orientation sufficient to disrupt the remaining fine solids and further separate the magnetic and non-magnetic particles and then subjecting the further disrupted fine solids to at least a second magnetic field, wherein the second magnetic field is oriented in a direction generally perpendicular to a flow direction of the disrupted fine solids and having a magnetic field strength sufficient to accumulate a portion of the magnetic particles from the depleted mixed stream on a second magnetic recovery surface from which the accumulated magnetic particles from the first and second magnetic recovery surfaces can be recovered.

[0011] These methods can also be implemented in other multi-stage configurations including those in one or more depleted mixed streams are exposed to a second magnetic field, wherein the second magnetic field is oriented in a direction generally perpendicular to a flow direction of the depleted mixed stream and wherein the second magnetic field is sufficient to accumulate a second portion of the magnetic particles from the depleted mixed stream on a second magnetic recovery surface after which the accumulated magnetic particles can be recovered from the first and second magnetic recovery surfaces.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Example embodiments described below will be more clearly understood when the detailed description is considered in conjunction with the accompanying drawings, in which:

[0013] FIG. 1 A illustrates an example magnetic rift scrubber assembly including a suspension tank 102 from which the suspension of composite particles is removed via a high-pressure pump 104 for injection through a nozzle or fitting 106 into a processing chamber 107 in which secondary high-pressure flows 108 are applied to the primary material stream 114. The disrupted flow is then exposed to a magnetic field induced by one or more magnets 110 that tend to separate magnetic particles onto surfaces 112 for subsequent collection.

[0014] FIG. IB illustrates a cross-sectional view of the secondary high-pressure assembly in which a plurality of nozzles or fittings are arranged and oriented to direct a corresponding plurality of secondary high-pressure flows into the primary material stream 114.

[0015] FIG. 2 illustrates another example magnetic rift scrubber assembly 200 in which a secondary high-pressure pump 216 is utilized for independently controlling the pressure of the secondary high-pressure flows 208 into the processing chamber 207. [0016] FIG. 3 illustrates another example magnetic rift scrubber assembly 300 in which a secondary high-pressure pump 316 is utilized for independently controlling the pressure of the secondary high-pressure flows 308 into the processing chamber 307. The example magnetic rift scrubber assembly 300 further includes an independent fluid supply 318 from which the secondary high-pressure flows are drawn, thereby providing additional control over variables including, for example, the primary fluid, additional additives and fluid temperature, that may be useful for improving the performance of the magnetic rift scrubber.

[0017] FIG. 4A illustrates another example magnetic rift scrubber assembly 400 in which the disrupted flow may be exposed to a series of magnetic fields induced by a plurality of magnets 410a-c for attracting the magnetic particles to onto a corresponding plurality of surfaces 412a-c for subsequent collection. As will be appreciated by those skilled in the art, this arrangement will provide additional control over variables including, for example, the relative lengths and surface configuration of the surfaces 412 as well as the relative strength and orientation of the applied magnetic fields that may be useful for improving the performance of the magnetic rift scrubber.

[0018] FIG. 4B illustrates another example magnetic rift scrubber assembly 402 that includes both primary and secondary disruption regions 407a, 407b in which a plurality of secondary high-pressure flows 408a, 408b can be applied to the primary material stream 414. As will be appreciated by those skilled in the art, this arrangement will provide additional control over variables including, for example, the relative pressures, flowrates, orientation and compositions of the secondary high-pressure flows that may be useful for improving the performance of the magnetic rift scrubber.

[0019] It should be noted that these Figures are intended to illustrate the general characteristics of methods, structure and/or materials utilized in the example embodiments and to supplement the written description provided below. These drawings are not, however, to scale and may not precisely reflect the precise structural or performance characteristics of any given embodiment, and should not be interpreted as defining or limiting the range of values or properties encompassed by example embodiments. DETAILED DESCRIPTION

[0020] The present invention takes advantage of the abrasive nature of fine magnetic particles, in combination with high-pressure fluid forces and magnetic fields. The fine solids containing the magnetic particles are typically suspended in an appropriate liquid including, for example aqueous solutions with a solids percentage of up to about 35%. The suspension is then passed through an apparatus as a high-pressure and highly agitated stream. The apparatus is further configured to apply a magnetic force to the high- pressure stream, the magnetic force being applied in a direction generally perpendicular to the direction of the fluid flow. The process may be maintained and/or controlled by varying one or more parameters including, for example, the solid contents of the incoming stream, the solvents and/or additives carrying the solids, the pressure of the incoming liquid stream, the pressure, direction and volume of secondary agitating stream(s), the strength of the magnetic force(s) and the orientation of the magnetic force(s) to achieve a desired degree of separation of magnetic particles.

[0021] The results obtained from these interactions are a function of the balance established and maintained between these parameters and, in particular, the fluid pressure(s) and the magnetic force(s) applied to the magnetic particles as they pass through the apparatus. For example, the fluid pressure and direction will affect the abrasiveness of the particle stream against the magnetic surface(s) created within the apparatus, while the strength of the magnetic field will affect the accumulation (and subsequent removal) of magnetic particles on the magnetic surfaces. In operation, however, neither of these parameters will tend to be static, however, as reducing the fluid pressure may increase the accumulation of magnetic particles, while weakening the magnetic field may reduce the abrasiveness of the impact interaction. Those skilled in the art will appreciate that, as a result, any operative apparatus design will typically provide for the generation and application of variable fluid pressures and/or variable magnetic strength.

[0022] Although the apparatus would typically operate at ambient temperatures, certain composite particle streams may see process efficiencies improved by controlling the temperature of the liquid stream. For some organic compounds including, for example, various petroleum hydrocarbons, increasing the temperature of the liquid stream to, for example, 80° C. or more, may dramatically increase the removal rate of petroleum hydrocarbons from the magnetic particles, by reducing the viscosity of these organic compounds. Conversely, when processing certain crystalline compounds, reducing the temperature of the liquid stream to, for example, 5° C. or less, may dramatically increase removal rates, by increasing the brittleness of these crystalline compounds, resulting in increased fracture rates at the same pressures and orientations. Special solvents (including, but not limited to benzene, toluene, and deuterium containing compounds such as CD ₂ C1 ₂ and CDFC1 ₂ , among others) can be utilized for extreme temperatures processing of exotic magnetic particle composites.

[0023] Depending on a variety of factors, such as the magnetic parti cle(s) of interest, the physio- chemical properties of the undesirable material, the desired output purity, and the desired treatment rate, the basic production apparatus, as illustrated in FIG. 1 A, may be modified through the addition or adjustment of a number of steps, each of which may, in turn, consist of several sub steps:

[0024] The process begins by screening out larger particles from the fine particle material that will be used in forming the liquid feed stream. Typically, any particles larger than 6,350 μηι should be removed from the feed material. Although modified apparatus can be designed for accommodating larger particle sizes, it is believed that improved performance will be achieved with feed materials having higher surface area to volume ratios.

[0025] The screened material is then vigorously mixed with a carrying liquid such that the magnetic particles are suspended within the liquid. For the purposes of this explanation, water (H ₂ 0) will be used as the liquid of choice, although other liquids, combinations of liquids and or other additives may be utilized. This mixing process could take place in a recirculating tank with a mixing prop, or any other form of mixing chamber vigorous enough to maintain the suspension of the solids.

[0026] Once the material has been prepared as described above, the liquid suspension is accelerated through a high-pressure pump, e.g., a pump having a minimum output pressure on the order of 2,000 psi (13.8 MPa). Depending upon the desired processing goals, much higher output pressures could be as high as 20,000 psi (138 MPa) or more. For any particular situation, it is preferred that the high-pressure pump provide for a variable output pressure to provide for adjustment of the conditions within the processing chamber during the course of the separation.

[0027] The output of the high-pressure pump described above is connected to one or more inputs of a magnetic rift chamber. In a typical apparatus, a majority of output of the high-pressure pump is connected to a primary chamber input whereby the primary liquid flow is directed along a path generally parallel to the longitudinal axis of the chamber. Two or more secondary high-pressure spray nozzles are oriented at an angle to the primary input stream, converging upon the primary input stream. The number of secondary nozzles is determined by the liquid type, magnetic particles in question, form of undesired particles, and processing goals. Apparatus configurations having as few as 2 and as many as 64 secondary nozzles have been demonstrated. FIG. IB illustrates an apparatus with multiple secondary nozzles. The nozzles may be supplied with high-pressure suspended liquid stream from the primary high-pressure pump, or may be supplied from a secondary liquid supply delivered through a secondary high-pressure pump as shown in FIGS. 2 and 3. The pressure provided at the high-pressure spray nozzles should typically be at least equal to the pressure of the primary liquid flow.

[0028] In addition to the front-end high-pressure spray system described above, the magnetic rift chamber includes at least one stage of processing magnets. These magnets may be permanent ferromagnets, electromagnets, bitter electromagnets (also known as bitter solenoids), or superconducting electromagnets. These magnets are typically oriented in such a fashion that their magnetic dipole moments are oriented parallel to the primary chamber input described above and are provided on the chamber opposite the wetted surface to establish a magnetic field of desired strength extending into the primary chamber as illustrated in FIG. 4A. The apparatus will typically include at least two such magnets arranged on opposite sides of the primary chamber, but multiple magnets may be utilized for improving the process efficiency for any given magnetic particle stream.

[0029] Depending upon the processing goals, multiple stages of high-pressure nozzles or magnetic rings can be implemented in a single magnetic rift chamber as illustrated in FIG. 4B. These stages could simply be repetitions of the initial stage, or be configured to provide varying levels of pressure and/or levels of magnetic field strength, depending upon the nature of the input stream(s). For example, input streams containing high levels of organic "spongy" compounds may be processed more efficiently by using multiple stages of decreasing pressure and field strength, while input streams containing other forms of undesirable compounds may experience superior processing efficiency using multiple stages of increasing pressure and field strength.

[0030] In the case of increased efficiency using multiple states of decreasing pressure and/or field strength, the separation of organic material into the liquid processing stream in the first stage reduces the interference of the organic compounds with the abrasive forces in subsequent stages. Conversely, in the case where undesirable solid components of the feed stream interfere with the application of high pressures and/or high magnetic field strength, entrainment of the interfering solid particles in the feed stream decouples them from the complex crystalline structures and allows the use of higher pressures and/or magnetic forces to create more abrasion of the crystalline structures against each other. As will be appreciated by those skilled in the art, the number of stages utilized in a magnetic rift assembly according to the invention can be quite large. Indeed, 30 or more stages could be utilized depending on a number of factors including, for example, the nature of the primary particulate material, the desired recovery yield, the presence of one or more contaminates, value of the recovered/residual material(s), budget and environmental issues.

[0031 ] As the high-pressure stream encounters the magnetic field in the primary separation chamber, magnetic particles from the stream will tend to be attracted to and accumulate against the rift chamber wall. Although the wall structure of the experimental rift chamber was smooth, it is believed that improvements in the initial accumulation of magnetic particles could be facilitated by modifying the collection surface using grooves or recesses cut into the wall structure.

[0032] Absent additional surface structure, however, the magnetic particles will tend to accumulate in a pattern that generally reflects the magnetic field lines present at the collection surface of the rift chamber. The level of accumulation is determined by the balance of competing forces applied to the magnetic particles by the stream input pressure and magnetic field strength. Excessive pressure (or insufficient field strength) will tend to result in reduced accumulation, while insufficient pressure (or excessive field strength) will tend to result in excessive accumulation that could lead to chamber blockage.

[0033] As noted above, the magnetic rift scrubber apparatus should be configured to allow for modification of the input pressure/magnetic field strength ratio to compensate for variations in, for example, the magnetic particle stream, the nature of the undesirable components within the feed stream and the configuration of the chamber. When operating under preferred conditions, the accumulation of magnetic particles along the rift chamber walls will form an abrasive, regenerative wall that simultaneously protects the outer permanent walls of the rift chamber while providing a surface against which the input streams impact.

[0034] For example, most of the magnetic particles typically found in steel sludge are below 25 μηι and may have been oxidized to some extent, resulting in a heterogeneous composition of magnetic, semi- magnetic, and lighter density particles. Therefore, at a certain predetermined incoming pressure the magnetic force should be stronger. A series of experiments conducted in which steel sludge was processed in a 2-inch (5.1 cm) chamber suggest an incoming pressure of 8,000 to 10,000 psi (55.2 to 68.9 MPa) exhibits acceptable performance when coupled with a magnetic field strength of 4,000 to 5,500 gauss. Following the rift chamber, a rotating drum magnetic system, well, known in the art, may be used to collect the clean magnetic particles.

[0035] The moisture content in the collected magnetic particles is an indicator of the effectiveness of the rift scrubber. Cleaner particles will be drier than particles still adhering to each other. This measure of effectiveness is valid within a range of particle sizes. The experiment has been carried out for particles below 25 μηι, as well as for 25 to 100 μηι, and 100 to 500 μηι. The moisture measurement is a better indicator for smaller particles than for larger particles. [0036] Another measurement of the effectiveness of a particular process would be to determine the total solid output mass from the end of the magnetic scrubber and compare it to the total solid input mass before the magnetic scrubber. The two masses should be substantially equal, i.e., should not reflect more that about 1-2% differential. If the solids mass out of the magnetic scrubber is reduced by more than about 1.5-2.0 %, the fluid pressure or magnetic force should be adjusted to improve the mass balance. The number of magnetic scrubbers or the length could also be changed if the solid percentages in and out of the scrubber are constant but the separation is insufficient.

[0037] On the other hand, in contrast to steel sludge, mill scale sludge is typically a more homogenous composite of magnetic particles ranging between 25 to 150 μηι. A series of experiments were conducted in which mill scale sludge was processed using a 2-inch (5.1 cm) diameter rift chamber suggest that an incoming pressure of 8,000 to 10,000 psi (55.2 to 68.9 MPa) shows acceptable performance when coupled with a magnetic field strength of 2,000 to 2,500 gauss.

[0038] A first experiment was conducted on a sample including magnetic particles having an average size distribution of less than 25 μηι and used a magnetic scrubber with a length of 18 inches (45.7 cm). The experiment was conducted at a pressure of 8,000 psi (55.2 MPa) and a magnetic flux of 3,000 gauss. The results of the experiment showed an average of over 94% separation of the magnetic particles from heavy hydrocarbons. A second experiment was conducted on a sample having a substantially similar average size distribution of magnetic particles (less than 25 μηι), but the particles were complexed with other minerals including aluminum oxide (12%), titanium oxide (2%), and zinc oxide (approximately 1 %) that were strongly bound to the magnetic particles. In this experiment, the separation efficiency of the 18 inch (45.7 cm) scrubber was less than 70 per cent. A third experiment was conducted at a pressure of 10,000 psi (68.9 MPa) and 4,000 gauss using an additional 18 inch (45.7 cm) scrubber arranged in series with the scrubber of the second experiment. The result of the third experiment was a nominal increase in efficiency to 76%. A fourth experiment was then conducted using the two 18 inch (45.7 cm) scrubbers in series, but adjusting the magnetic force to between 3,500 and 4,000 gauss, and increasing the flow velocity by boosting the pump pressure by 20 % to a range of approximately 15,000 psi (103.4 MPa). In the fourth experiment, the separation efficiency increased to 88 to 95 %. The table below summarizes the experiments.

[0039] The strength of the magnetic field and incoming pressure for the above examples could change if the contaminants or non-magnetic materials are of a more complex structure. The reason is that the bonding forces between particles are higher in such structures. For example, in mine tailings, with a high level of aluminum silicate and/or aluminum oxide, or with sludge produced by the Bayer aluminum process, it is expected that a minimum of 15,000 psi (103.4 MPa) pressure would be required in order to overcome the bonding forces in the crystalline structures. In such a case, the combination of increased pressure with a magnetic field strength of 2,500 to 3,000 gauss would produce acceptable performance. Recognizing that he variety of applications is very broad, several rules-of-thumb apply:

In general, increased pressure improves particle separation.

In general, magnetic field strength improves the attraction of magnetic or ferromagnetic particles to the rift scrubber surface.

In general, the length of the scrubber magnetic field improves particle abrasion and thus contaminant desorbtion. In general, the strength of the magnetic field at the center of fluid flow affects the retention of magnetic particles in the scrubber and thus the ease of stripping the particles from the rift scrubber surface.

For hydrocarbon contamination of small particles, the most important factors are pressure and magnetic field strength. As the magnetic scrubber length increases, the efficiency increases.

For complex oxide compositions, initial high pressure to insure penetration of the matrix is important, as is a high magnetic field. For complex oxide compositions, additional processing appears to yield marginal returns.

[0040] It is generally preferred that the magnetic field strength applied should be selected so as to provide an acceptable accumulation rate while still allowing for a substantial flow of the liquid suspension through the rift chamber in order to avoid blockage incidents. During operation, there will be significant turbulence, abrasion, and sheering occurring in the top layers of accumulated particles. These physical interactions serve to strip the magnetic particles from the associated non-magnetic materials through a synergistic combination of fluid friction and internal friction.

[0041] As will be appreciated, the magnetic particles within the feed stream will be subject to force vectors from both fluid pressure and magnetic force, while the non-magnetic particles in the same feed stream will be subject to only those vectors resulting from fluid pressure. In preferred operating regimes for the disclosed apparatus, it is this force differential, combined with the turbulence, abrasion, and sheering occurring in the accumulated particles, that is sufficient to overcome the competing forces associated with, for example, surface tension and crystalline structure of the associated undesirable materials. The result is improved, separation of magnetic and non-magnetic particles from within the suspended solids of the feed stream. The strength of the fluid flow moves magnetic and nonmagnetic particles out of the scrubber chamber. The processed suspended solid stream may then be output for the previously mentioned standard industry magnetic separation of the magnetic particles, and standard industry liquid/solid separation of the suspended solids. [0042] Many different fine particle streams containing magnetic compounds are generated by a range of industrial processes worldwide. In many instances, the difficulty of separating the desirable magnetic components of these streams has rendered these materials "low value," and in some cases, as has resulted in their classification as waste streams. Industry state of the art reclamation treatments for such materials frequently require the use of extremely high temperatures to oxidize organic compounds and/or the sintering of inorganic compounds. Accordingly, the fuel and/or energy consumption associated with these conventional operations often outweighs the economic value of the recovered material. Furthermore, materials containing organic compounds may create significant amounts of pollution when oxidized, including undesirable by-products such as dioxins and furans. The method and apparatus detailed herein provides at least the following advantages:

For many waste streams, processing may occur at or near ambient temperature, dramatically reducing fuel requirements.

As a liquid process, materials handling may generally be conducted using industry standard equipment, and as a liquid process, the risks of gaseous emissions are dramatically reduced for any given particle stream.

The process is easily scalable, with a single, modest-sized unit able to handle 100s of tons per hour. A typical production unit would process 150 to 200 tons per hour, and if greater production was required, additional apparatus in unlimited number could be operated in parallel.

The process achieves the separation of magnetic particles in a near-pure form, avoiding end-of-life recycling, and returning materials to the industrial cycle. This may enable many industrial plants to reduce waste significantly and, in some instances, provide for a substantially zero-waste footprint.

[0043] As will be appreciated, the various components of the material feed can be handled in a series of stages using a corresponding series of magnetic rift scrubbers and other conventional unit processing equipment to ensure that composite particles are subjected to mechanical and magnetic forces and/or solvent combinations sufficient to separate a portion of the magnetic fines from composite particles and/or other contaminates present in the initial feed stream. Although the range of compositions and contaminates is quite large, it is believed that each source of such materials can be characterized with sufficient accuracy using conventional engineering principles and methods. Once characterized, suitable processes may be developed in accord with the present disclosure to achieve the desired level of cleaning and/or separation of the magnetic fines.

[0044] Those skilled in the art will also appreciate that the material preparation process(es) and separation and recovery process(es) and apparatus, i.e., the front end and back end of a unified process and corresponding apparatus may be further modified for particular applications by taking into consideration such factors as the type of raw materials being treated, the contaminate loading level (if any), the composition and size range of the target particles and the intended use of the recovered material(s) and/or residual fractions. Those of ordinary skill in the art will appreciate that the equipment and process fluids may be adapted to the particular demands and requirements of a particular application.

[0045] While the invention has been particularly shown and described with reference to certain example embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the following claims.