MXPA97001922A - Apparatus and procedure for the separaciongravitacional de particulas soli - Google Patents

Abstract

The present invention relates to an apparatus for the gravitational separation of particles having differences in density, the particles being initially mixed in an aqueous pulp, characterized in that the mixture comprises two or more types of particles that oscillate from relatively low density particles. to particles of relatively high density, the apparatus comprising: (a) a tubular column having an upper portion that includes a low density bed zone, a lower portion that includes a high density bed zone, and an intermediate portion that it includes a pulp entrance zone between the upper portion and the lower portion, each of the beds containing a packing material that defines a large number of small steps and interconnected chambers that extend in a circuit pattern through the respective ones zones, (b) medium to form a dispersion of aqueous pulp, (c) medium to feed the dispersion d and aqueous pulp inside the pulp inlet for flow into the column and through the flow passages, (d) means for the hydraulic classification of the aqueous pulp in the column to form a bed of low particle density. low density in the area of the low density bed and to form a high density bed of high density particles in the area of the low density bed, (e) means to discharge a wash fraction containing low density particles of the aqueous pulp from the upper portion of the column above the low density bed zone, and (f) means for discharging a concentrate fraction containing high density particles of aqueous pulp from the lower portion of the column by below the high density bed zone

Description

APPARATUS AND PROCEDURE FOR GRAVITATIONAL SEPARATION OF SOLID PARTICLES DESCRIPTION The present invention deals with gravitational separation and, more particularly, deals with an apparatus and method for the gravitational separation of solid particles having density differences. Prior methods and apparatus for the purification of solid particles, for example, iron ore, include systems such as those set forth in Yang, U.S. Patent 4,592,834, issued June 3, 1986, which is incorporated herein by reference. by reference. The above procedures for the mechanical separation of silica (SiO2) from iron ore (eg, magnetic concentrate) at high processing rates have not been able to either (i) reduce silica levels of more than 5.5 percent in weight based on the total weight of the iron ore to less than 5.0 percent by weight based on the total weight of the iron ore or (2) recover the iron values present in the product to more than 95 percent based on weight total iron ore in the feeding pulp. These problems related to relief in combination of (1) low silica levels (reduced) in the final product and (2) high (improved) iron recovery levels generally resulted from the inability (or inefficiency) of the above procedures in the separation of iron fines (particles whose size is less than 150 mesh) or 100 microns) of silica fines (less than 150 mesh in size or 100 microns). Several raw iron ores contain agglomerates of iron-rich material and silica-rich material, and inadequate crushing (crushing, pulverizing or milling) of the iron ore results in inadequate separation of the iron material and the silica material. Accordingly, the above procedures having a substantial amount of silica in conjunction with iron, often resulted in undesirably high silica impurities (greater than 5 percent by weight) in the final iron product. Conversely, excessive grinding (pulverization, milling or grinding) can result in high levels of fines (mesh particle sizes of less than 150) which can not be effectively and efficiently separated by the above procedures, such as of flotation or magnetic separation procedures. Traditionally, gravity separation of coal or ore is carried out in a variety of separation devices such as thickeners, cyclones, tables, hydraulic sorters, spirals and separated heavy media. These conventional methods depend on the size, shape and densities of the particles to be separated as well as the conditions of fluid dynamics in the separators. The separation efficiency, however, deteriorates as the feedstock becomes finer or if the particle sizes vary greatly. The separation of heavy media for cleaning coal, for example, is only effective for the treatment of coarser particles than mesh 28. Although flotation results in particle sizes below 28 mesh, flotation can not be used to reject particles of pyrite that tend to coalesce with carbon as a rubbing product due to its similar, superficial hydrophobicities. In addition, the results of conventional flotation techniques are relatively deficient compared to the washability of coal based on density. Additionally, conventional hydraulic classification methods have typically experienced instabilities and vorticity in the dense particle media, resulting in undesirable vertical mixing of the media. In addition, small particle sizes typically result in undesirably high levels of short circuit in hydraulic classification procedures. In consecuense, there is a need for apparatus and methods that, in combination, provide high purity product (eg, low silica content iron ore) and will provide high levels of product recovery (eg, iron). The present invention provides a separation method and apparatus that reduce the levels of silica or other gangue levels efficiently and effectively, while providing high levels of recovery of the desired solid particles, preferably mineral values from the minerals. The procedure and apparatus reduce instabilities and vorticity and, with this, vertical mixing decreases. Additionally, the method and apparatus reduce the short circuit and allow efficient and efficient separation of small particles by efficiently creating small-sized hydraulic classification cells. The process comprises the gravitational separation of particles of relatively high and low density which, initially, are mixed in an aqueous pulp. The method preferably comprises (a) providing a tubular column having an upper portion that includes a low density bed zone, a lower portion that includes a high density zone, and an intermediate portion that includes a pulp entry zone , preferably between the upper portion and the lower portion; (b) providing in the upper zone and / or the lower zone a packing material that defines a large number of flow passages that extend in a circuit pattern through the respective zones; (c) the introduction of the pulp into the pulp entrance zone for flow through the flow passages of the packing materials to form a bed of low particle density in the upper zone and a high bed. density of particles in the lower zone; (d) the hydraulic classification of the beds gives rise to the gravitational separation of the high and low density particles in the pulp, leading to the migration of the low density particles towards and into the low density bed and giving rise to to the migration of the high density particles towards and for inside the high density bed; (e) removing a wash fraction containing low density particles from the upper portion of the upper zone column; and (f) removing a fraction of concentrate containing high density particles from the lower portion of the column below the lower zone. The apparatus is particularly suitable for the gravitational separation of the particles having density differences in which the particles are, initially, in mixture with the aqueous pulp, the mixture containing low density particles and relatively high density particles. The apparatus is preferably designed to have: (a) a tubular column having an upper portion that includes a low density bed, a lower portion that includes a low density bed zone, and an intermediate portion that includes an area pulp inlet, preferably between the upper portion and the lower portion, each of the beds containing a packing material defining a large number of small steps extending in a circuit pattern through the respective zones; (b) means for forming a dispersion of the aqueous pulp; (c) means for feeding the aqueous pulp dispersion into the pulp inlet for flow, within the column and through the flow passages; (d) means for hydraulic classification (vibrating) the aqueous pulp in the column to form a bed of low density of low density particles in the area of the low density bed and to form a high density bed in the high density bed zone; (e) means for discharging a fraction containing low density particles from the aqueous pulp from the upper portion of the column above the low density bed zone; and (f) means for discharging a fraction containing high density particles of aqueous pulp and the lower portion of the column below the high density bed zone. The gravitational separation is achieved by vibration (preferably hydraulic classification) of the bed zones and more specifically the lower bed. Vibration can be achieved by pulsation with water, pulsation with air or mechanical vibration, although the pulsation with water is the preferred means to generate vibration in the beds of the packed column. Although this is not critical, it is preferred that the present invention use, in combination, the column having reduced cell sizes, the high density bed zone and the vibration for gravity separation of the low density particles from the high density particles. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of an apparatus for gravitational separation in accordance with the present invention; Figure 2 is an exploded perspective view of a portion of the corrugated sheets that constitute a section of the packing for the column. Suitable aqueous pulps containing mixtures of relative low density and high density particles include minerals, carbon or other particulate materials, preferably iron minerals containing silica impurities, and most preferably comprise a magnetic concentrate of an iron ore. of taconite that contains more than 60 percent by weight of iron based on the total weight of the particles, and more than 5 percent by weight of SiO2 (silica) based on the total weight of the particles. The final concentrate, preferably concentrated iron product contains less than 5 percent by weight of gangue material, more preferably less than 4.5 percent silica, and most preferably less than 4.0 percent by weight of silica. The low level of gangue material, silica material, in the final concentrated product allows the reduction of the lime required for the final furnace processing of the final iron ore product and will result in reduced slag formation in the blast furnace by of the end user. Potentially, reduced levels of silica could result in the ability to deflect the blast furnace completely because the silica levels achieved by the present process can be reduced to 2 percent or lower, depending on the release characteristics of the material of food. The apparatus and giavitational separation method of the invention can be used to separate a wide variety of materials in a wide range of particle sizes. It is particularly adaptable for the separation of mineral values from the gangue into fine-grained minerals, such as low-grade magnetic taconite minerals, from the Lake Superior area.

The density separation process may also be used to improve other oxidized or partially oxidized iron minerals, clean coal to remove mineral matter (especially pyrite), or for the recovery of other heavy minerals such as rutile, ilmenite, cassiterite, from finely crushed minerals and / or waste. The invention will be described in relation to the purification of iron ore and coal. The apparatus for gravitational separation (10) provided by the invention includes a tubular column (12) having an upper portion (14) and a lower portion (16), a pulp inlet (18) for introducing an aqueous slurry or pulp of a magnetic taconite mineral into the column (12) at an intermediate site , and preferably pressurized water inlet (22) to introduce water pulses into the lower portion (16) of the column (12). The column (12) may be generally vertical, as illustrated in Figure 1, or inclined at an angle with respect to the vertical. It is critical, however, that sufficient verticality be present to provide adequate gravitational forces to keep the beds separated from high and low density particles, as described in greater detail, below. The column (12) is partially filled with means for reducing the cell size and channeling the packing (24) as such, which defines a large number of small flow passages and small chambers that extend in a tortuous or circuit pattern in all the upper and lower portions (14 and 16). A concentrated fraction (33) containing the high density particles in the aqueous pulp is collected in a concentrate chamber (32) at the bottom of the column (12) and it is discharged through an exit (34). Although this is not particularly critical, the concentrate chamber (32) preferably has a conical shape, as illustrated in Figure 1, to promote the discharge of the concentrate fraction. The concentrate fraction is removed, preferably, through the outlet (34) by a conventional variable flow pump (36) as the final concentrate product (36). While the column (12) can have several configurations in cross section, in the specific construction illustrated, it has a square cross section. The dimensions of the cross section and length of the column (12) are governed by the type of aqueous pulp that is being treated, the particular type of packaging (24) used, the desired performance, and other variables of knowledge of those with experience in the art.

The package (24) can be in a variety of different shapes capable of providing a substantially plugged flow condition and which defines a large number of flow passages and chambers that extend in a tortuous or circuit pattern within and between the upper portions and bottom of the column (12). High density particles (iron-rich particles) form a high-density bed in the lower zone, and low-density particles (particles rich in silica) form a low density bed in the upper zone. The packaging facilitates the maintenance and stabilization of the beds, and thus facilitates the separation of the beds. The vibration allows the movement of high density particles from the pulp feed in the high density bed, but effectively allows the high density bed to maintain a high overall density and sufficient compaction to allow it to withstand penetration by part of the low density particles. The use of the dispersant resists the agglomeration of the individual particles, thus allowing the continuous flow of the high density particles toward the bottom of the column and the low density particles toward the top of the column. Suitable packaging includes conventional packing materials used in packed tower for vapor-liquid transfer operations, such as Raschig rings, Berl chairs, partition rings and the like. This package may also include vertical, horizontal and inclined sheet structures with or without perforation. Packing functions as a means to reduce cell size and channelization in the column. In the preferred embodiment illustrated, the package (24) comprises a plurality of sections (38a-38f) of vertical extension plates (40). Each section includes a plurality of the sheets (40) and means for laterally separating the sheets (40) (separating means) to define a plurality of relatively small flow passages between the adjacent sheets (40). In the specific construction illustrated, such separating means comprises, but without limitation, evenly spaced rows of corrugations (42) in each sheet (40). The corrugations (42) extend diagonally, for example, at an angle of approximately 45 ° with respect to the horizontal, to eliminate the vertical flow passages of substantial length. The angular orientation of the corrugations (42) may vary to control the flow through the flow path. For example, this flow length can be increased by decreasing the angle of the corrugations (42) with respect to the horizontal. In order to further improve the tortuous or circuit pattern of the defined flow passages between the adjacent plates (40), the corrugations (42) of the alternating plates (40) preferably extend in the opposite direction, in the form illustrated in] Figure 2. That is, the corrugations in a sheet extend at an angle with respect to the corrugations in the next sheet. Also, alternate sections are placed in such a way that the vertical planes of the sheets in a section are angularly related (preferably to 90 °) with respect to the vertical planes of the sheets in the adjacent section. With reference to Figure 1, the vertical planes of the plates (40) in the sections (38a, 38c, and 38e) extend perpendicularly with respect to the plane of the page and the vertical planes of the plates in the sections (38b, 38d and 38f) extend parallel to the plane of the page. The packing sections (38c and 38d) that are in the vicinity of the pulp inlet (18) are preferably separated to provide a substantially unobstructed feed chamber or chamber (44). The packing sections (38a, 38b, and 38c) that are above the feed chamber (44) constitute the upper zone of the column (12) and the packing sections (38d, 38e, and 38f) that are by below the feed chamber (44) constitute a lower zone. The low density bed that is rich in gangue (silica) (for example, silica level more than 5 percent with respect to the feed material) will be present in the upper zone, and the high density bed that has reduced levels of gangue (silica) (for example, more than 0.5 percent by weight, less silica than that of the feedstock). In a typical operation, an iron ore such as magnetic taconite or partially oxidized taconite is crushed into a particle size suitable for the release of mineral values, and is preferably ground to achieve a particle size of less than 100 microns. , for example, a mesh size of at least 150 mesh (the values of the mesh number and the size of the particles are inversely related, that is, the higher the mesh value the smaller the size of the particles) . A means to remove larger particles such as a sieve having a mesh size of 150 (or finer) is preferably used to produce a feed pulp consisting of small particles (for example, particles less than 100 microns in diameter or less than 150 mesh in size). An aqueous slurry or pulp of the particles is introduced into a stirred treatment vessel (46) for the addition and mixing of suitable dispersant. Suitable dispersants for the iron ore particles include, for example, sodium silicate. The most preferred dispersant is the sodium silicate solution sold by PQ Corporation under the trademark "O" Brand or "N" Brand. After the treatment, the pulp is removed from the container (46) by means of a pump (48) and introduced into the column through the pulp inlet (18). The flow rates of the various jets can be adjusted to obtain a balance of the material that provides the most efficient separation of the high density particles (eg, iron oxide) from the low density silica particles (e.g. bargain). The apparatus and method of the invention have several advantages over conventional apparatuses and methods. They provide effective and efficient separation of very small particles that have density differences, and in the case of iron ore that contains silica impurities (carbon dioxide) providing sufficient separating levels to reduce silica levels to less than 5 percent in the final concentrate, with high recoveries of concentrate, for example, recovery of iron that exceeds 95 percent. In addition to being used for single stage separation, the apparatus of the invention can be used in combination with conventional separation steps and two or more can be used in series. The upper sections (38a-38c) form an upper bed zone (54) in which a bed (56) of low density particles (silica rich particles) is present. The lower sections (38d-38f) form a lower bed zone (58), in which a bed (60) of high density particles (iron-rich particles) is present. The feed chamber (44) is at the intermediate site, preferably between the upper bed zones and the lower bed zones (54 and 58). An upper chamber (26) is located above the upper zone (54) and is in communication with an outlet (28) for the removal and flow of low density particles (the fraction of the landslide jet (30)) to from column (12). The concentrate product jet (35) leaves the pump (36) and contains high density particles. The crushed ore stream (49) is pre-screened by screen mesh (50) preferably of a 150 mesh size, or other suitable means for removing large particles from the jet, to produce a stream of mineral pulp (62) and a jet of large particles (51) which can be either recirculated back to the crushing or disposed as waste. The mineral pulp jet is fed into the treatment vessel (46) and mixed with dispersants from the dispersing jet (52) to produce a dispersed pulp jet (64). A boosted water pump (20), or other suitable means for vibration (hydraulic classification) of the beds (56, 60) (more particularly the bed (60)) is used to gravitationally separate the particles, while minimizing the penetration of low density particles within the low density bed (60). Preferably, the upper end of the bed (60) forms an upper contact surface (66) that resists the penetration of low density particles. In a steady state operation, the concentrate discharge from the high density bed (60) has a solid content of at least 95% by weight based on the total weight of the particles present in the feed stream (64). ), more preferably has a solids content of at least 98% by weight, and, more preferably, at least 99% by weight. The boosted water provides an impulse that provides a change in water pressure of at least 0.05 psi, more preferably between 5 and 20 psi, and more preferably between 10 and 15 psi. Preferably, the pulse occurs at frequencies between 5 and 120 per minute, more preferably between 10 and 60 per minute, and more preferably between 15 and 30 per minute.

Another embodiment of this invention deals with the method of separating particulate material such as the removal of mineral matter from coal, using a bed of controlled density. This can be achieved either by adding a heavy medium, or by applying the principles of fluid dynamics to use the heavier particles in situ, such as pyrite in the coal, as the dense media. The initial laboratory test shows that a clean coal of 8.8% ash at 52.8% yield can be produced from the Alabama Pratt crude coal feed (27.7% ash and 50% -22 μm) using a packed column which pulsations are imposed with a reciprocating plunger; The fraction of fines, that is, mesh -500, which contains large quantities of clay can be rejected either before or after the density separation. This indicates that the concept is applicable to a wide range of particle sizes and that efficient separation can be achieved by the present invention for several feed jets. The present invention allows the elimination of the expensive requirement of using magnetite means in the purification of coal. Instead, carbon pyrite (or the heavy in situ mineral constituent of the feed) may be used to control the specific gravity of the density bed.

The greater the number of cells, the greater the degree of separation of the constituents. The separation can be matched to the number of cells found by the material in the separation process. An analogy may be made with the theoretical sheet calculations and the design of equipment used by chemical engineers in the design of the absorber designated in Perry & Chilton, Chemical Engineer's Handbook, 5a. Edition, Section 14, pages 10-13. The packaging material of the present invention acts to effectively reduce piping from the inlet to the outlet. Preferably, the present columns have an effective height of at least 3 separation cells, more preferably between 10 and 100 efficiency separation cells. The packing improves the drag of the material as it moves, which improves the separation efficiency more. The gravitational separation of the present tubular column does not require flotation, magnetic or cyclone separation, and thus is free, preferably, of flotation agents, separation equipment and cyclone generators that generate magnetic field. The system may use or be free of flocculants. Preferably, the tubular column is square cross section and may optionally be of rectangular or circular cross section.

The column preferably has a height of 6 inches at 20 feet. The packaging material preferably has a pore or chamber diameter of between 5 and 100 times the average diameter of the number of the particles. The package preferably provides chamber volume that is 125 to 1,000,000 times the number of the average particle size of the particles. Preferably, the column has a free area of 0.25 m2 to 8,000 m2, more preferably 16 m2 to 64 m2. Preferably, the package is corrugated plate packaging which is arranged in sections having a plurality of parallel plates, and each section (preferably 90 °) is rotated about a vertical axis relative to the adjacent section. Corrugated sheets have the advantage of minimizing mineral plugging in the column, compared to other types of packaging such as rings. The flow rate of the liquid through the column is sufficient to create a flow in the upper zone that exceeds the terminal velocity of the low density particles. The terminal velocity may be determined by means of the Stokes Law, with the variables of particle diameter-size, density, and viscosity of the liquid. Control can be achieved by controlling the feeding rate or by using an additional liquid inlet to maintain sufficient liquid flow in the upper zone. The frequency of hydraulic classification is preferably relative to the particle size in a ratio of. the inverse of the particle size and, preferably, it is a function of the inverse particle size. Bed densities may also be controlled to yield a desired degree in measurement per point of feed rate and auxiliary water. Typically the particles will have a typical density between 2.6 and 2.7 g / cm3 and the desired product particles will have a typical density of between 4 to 10 g / cm3 for iron and other minerals. If the coal were to be separated from the clay, then the gangue material will typically have a density of 2.6-2.7 g / cm3 and the coal will have a typical density of 1.2-1.6 g / cm3. The particle differences are preferably at a percentage density difference of at least 30%. The packing reduces the channeling and breaks the vortices in the column. EXAMPLES The following examples illustrate the high recovery levels of the low silica content iron ore achieved with the present apparatus and process. A 12-foot-tall column that has a circular cross section of 3 inches in internal diameter included two 5-foot sections of packing plates. Each packing section was packed with 10 layers of corrugated sheets, the corrugation of the sheet was 1/2 inch high and extended approximately 45 ° with respect to the horizontal, and the layers or alternate sections were oriented at 90 ° the one with respect to the others. A magnetic concentrate of taconite was ground from Mine A, which has a head test (feeding) of 66.42%. Fe and 5.77% Si02 up to approximately 98% - 150 mesh and was pre-treated to remove particles larger than 150 mesh in size. The pulp was treated with a dispersant to minimize agglomeration of the particles during processing. The feed of pre-treated aqueous pulp containing about 20 percent by weight solids was pumped into the intermediate feed zone of the column at a feed rate of approximately 120 lbs / hr. Wash water was introduced into the bottom of the column by applying alternately and leaking water pressure to approximately 10 pounds / square inch from a pulsation chamber (this may vary in accordance with the total height of the column). The percentage by weight of concentrated product exceeded 90% of the original solids content of the feed pulp and resulted in an iron recovery that exceeds 95% based on the total iron content of the aqueous pulp. Examples 1A-1B Magnetic Concentrate from Mine A (98% - 150 mesh) Product Example 1A% Weight% Fe% SiO% Fe Dist Conc. 96.18 67.41 4.52 97.78 Delay 1.94 39.44 39.44 1.15 Mesh 150 1.88 37.87 38.89 1.07 Cale. Head 100.00 66.31 5.71 100.00 Product Example IB% Weight% Fe% Si02% Fe Dist.

Conc. 93.95 67.66 4.62 95.78 Delay 4.17 50.09 21.70 3.15 Mesh +150 1.88 37.87 38.89 1.07 Cale. Head 100.00 66.37 5.97 100.00 Note that the small fraction of large particles initially screened in the pre-taming step (+150 mesh) showed high levels of silica. The pre-tamped in Examples 1A and IB added 1.88 percent by weight of the initial pulp. Observe the silica levels of less than 5 percent by weight of the concentrated products, and note the iron recovery levels that exceed 95%. This combination of low silica levels in the final product and high iron recovery rates obtained by gravitational separation is as surprising as it is unexpected and is especially unexpected in view of the small particle sizes used in the present process. Examples 2A and 2B Magnetic Taconite Crude from Mine A (85% - 325 mesh) Product Example 2A (Crude = 100% by weight)% Weight% Fe% Si02% Fe. Dist.

Conc. 34.88 67.93 4.02 76. 71 Delay 65.12 11.06 67.50 23. 29 Cale. Head 100.00 30.89 45.36 100. .00 Exemplary Product < or 2B% Weight% Fe% Si02% Fe. . Dist.

Conc. 33.27 70.51 1.20 75. .59 Delay 66.73 11.53 67.29 24 .41 Cale. Head 100.00 31.03 45.30 100 .00 Examples 3A and 3B Magnetic Concentrate of Mine B (80% - 325 mesh) Example 3A (Magnetic concentrate = 100% by weight) * Plant Product Data% Weight% Fe% SÍO2% Fe. Say: Conc. 87.22 69.28 2.23 97. .16 Dislove 12.88 13.65 69.14 2 .84 Cale. Head 100.00 62.18 10.85 100 .00 Example 3B Product% Weight% Fe% Si02% Fe. Dist Conc. 87.95 68.83 3.10 99.79 Dislove 12.05 10.05 72.23 0.71 Cale. Head 100.00 61.75 11.43 100.00 * The plant flow diagram includes only one-stage inverse buoyancy. Note the improved results of the present method on the compared plant data using a conventional method. Examples 4A and 4B Magnetic Taconite Crude from Mine B (80% - 325 mesh) Example 4A (Crude = 100% weight) * Plant Data Product Weight% Fe SiO-% Faith. Dist »Fe% Fe Rec.

Conc. 33.29 69.88 1.82 68.40 66.3 58.5 Delay 66.81 16.09 66.85 31.60 Cale. Head 100.00 34.01 45.27 100.00 Example 4B Product Weight% Fe% Si02% Fe. Dist. Conc. 36.52 67. .57 4.38 70. .95 Dislove 63.48 15. .91 67.19 29 .05 Cale. Head 100.00 34, .78 44.25 100 .00 * The plant flow chart includes magnetic separation and inverse float. Note the improved results of the present method on the compared plant data using a conventional method. Example 5 Simplified Procedure for Cleaning Coal Using the Density Bed Separator Carbon feed was crushed to fine particle sizes and a 150 mesh screen was used to pre-screen large particles from the feed stream. Then, the feed jet was sent to a density bed separator according to the present invention and then the upper low density jet was further screened and oversized particles from there were the clean coal product and the undersized particles from there they formed a mud of clay from which it was disposed. The high density jet constituted the landslides and comprised mineral / pyrite.

Results of the above test: The results of the Pratt Alabama Vein Coal Clean Test (27.7 ashes) using the present separation procedure. Note the low level of ash 8.8% of the product compared to the feed that has an ash level of 27.7%. Product% Ash% Rend. % CMR1 Clean Carbon Product 8.8 52. .8 66. .6 Mesh sludge -500 40.4 33. .6 27. .7 Bed depressions 69.3 13. .6 5. .7 Combination Lateral Dislodges 48.7 47 .2 33. .4 Cale. Head 27.7 100 .0 100 .0 * Recovery of combustible material

Claims (20)

1. CLAIMS 1. An apparatus for the gravitational separation of particles having density differences, the particles being initially mixed in an aqueous pulp, characterized in that the mixture comprises two or more types of particles ranging from particles of relatively low density to particles of relatively high density, the apparatus comprising: (a) a tubular column having an upper portion that includes a low density bed zone, a lower portion that includes a high density bed zone, and an intermediate portion that includes an area inlet of pulp between the upper portion and the lower portion, each of the beds containing a packing material that defines a large number of small steps and interconnected chambers that extend in a circuit pattern through the respective zones, ( b) medium to form an aqueous pulp dispersion, (c) medium to feed the aqueous pulp dispersion within of the pulp inlet for flow into the column and through the flow passages, (d) means for the hydraulic classification of the aqueous pulp in the column to form a bed of low density of low density particles in the area of the low density bed and to form a high density bed of high density particles in the area of the low density bed, (e) means to discharge a wash off fraction containing low density particles of the aqueous pulp originating from the upper portion of the column above the area of the low density bed, and (f) means for discharging a concentrate fraction containing high density particles of aqueous pulp from the lower portion of the column below the zone. of high density bed.
2. 2. An apparatus in accordance with the claim 1, characterized in that the packing means comprises a plurality of vertical extension sheets, and a separating means for laterally separating the sheets to define a plurality of flow passages between the adjacent sheets.
3. 3. An apparatus in accordance with the claim 2, characterized in that it includes a plurality of separate and vertically adjacent sections of the sheets.
4. 4. An apparatus in accordance with the claim 3, characterized in that the sections are oriented in such a way that the vertical planes of the sheets in each of the sections are angularly related to the vertical planes of the sheets in the adjacent section, and where the separating means comprises rows of corrugations in each of the plates that extend diagonally in relation to the horizontal.
5. 5. An apparatus according to claim 4, characterized in that the corrugations of adjacent plates extend in opposite directions.
6. 6. An apparatus according to claim 1, characterized in that the apparatus comprises a means for pre-tasting the aqueous pulp before entry, removing the pre-mixing medium from large particles from the aqueous pulp to produce an aqueous pulp having a mixture of particles having a size of less than 150 mesh.
7. 7. An apparatus according to claim 1, characterized in that the apparatus comprises a means for producing an aqueous pulp having a mixture of particles comprising at least 99 percent by weight of particles having sizes of less than 150 microns based on the total weight of particles in the pulp.
8. 8. An apparatus according to claim 1, characterized in that the apparatus comprises a means for producing an aqueous pulp wherein the mixture consists of particles having sizes of less than 150 microns.
9. 9. An apparatus according to claim 1, characterized in that the hydraulic classification means comprises a water-driven pump and a water inlet located below the lower portion to send water pulses into the bed of high density in quantity. Sufficient for the hydraulic classification of the beds and for the gravity separation of high density and low density particles.
10. 10. A process for gravitational separation of relative high and low density particles that are initially mixed in an aqueous pulp, characterized in that the method comprises: (a) providing a tubular column having an upper portion that includes a low density bed zone, a lower portion that includes a high density bed zone, and an intermediate portion that includes a pulp entrance zone between the upper portion and the lower portion; (b) providing in the upper zone and the lower zone a packing material that defines a large number of flow passages that extend in a circuit pattern through the respective zone; (c) the introduction of the pulp into the pulp inlet zone for flow through the flow passages of the packing materials to form a bed of low particle density in the upper zone and a high density bed of particles in the lower zone; (d) the hydraulic classification in the beds to cause the gravitational separation of the high and low density particles in the pulp causing the low density particles to flow towards and into the low density bed and causing the particles to migrate. high density towards and for inside the high density bed; (e) the removal of a washout fraction containing low density particles from the upper portion of the column above the upper zone, and (f) the removal of a fraction of concentrate containing high density particles from the upper portion of the column. the lower portion of the column below the lower area.
11. 11. A process according to claim 10, characterized in that the pulp contains a mineral that includes a mixture of particles with mineral value and bargain particles, the pulp is prepared for separation by gravity by treating the particles with a dispersant that It is effective to reduce the agglomeration of the particles in at least one of the beds.
12. 12. A method according to claim 11, characterized in that the ore is an iron ore.
13. 13. A method according to claim 10, characterized in that the package comprises a plurality of vertically adjacent and separated sections of sheets with vertical extension; and a separating means for laterally separating the sheets to define a plurality of passages and flow chambers.
14. A method according to claim 13, characterized in that the sections are oriented in such a way that the vertical planes of the sheets in a section are angularly related to the vertical planes of the sheets in the adjacent section, and where the separating means It comprises rows of corrugations in each of the sheets that extend diagonally in relation to the horizontal.
15. 15. A method according to claim 14, characterized in that the corrugation of the adjacent plates extends in opposite directions.
16. 16. The method of claim 10, characterized in that the hydraulic classification comprises sending water pulses into the beds and going up through them.
17. The method of claim 16, characterized in that the particles in the pulp mixture consist of parts having particle sizes less than 100 microns.
18. 18. The method of claim 16, characterized in that the mixture of particles of the pulp comprises at least 99 percent by weight of particles having sizes of less than 150 mesh.
19. 19. The method of claim 16, characterized in that it comprises a means to remove particles having a mesh size greater than 150 mesh from the pulp before entry.
20. 20. A process for gravitational separation of relative high and low density particles that are initially mixed in an aqueous pulp, characterized in that the method comprises: (a) providing a tubular column having an upper portion that includes an area of low density bed, a lower portion that includes a high density bed zone, and an intermediate portion that includes an entry zone between the upper portion and the lower portion; (b) providing in the column a means to define a large number of steps through the column; (c) introducing the pulp into the pulp inlet zone for flow through the flow passages to form a bed of low particle density in the upper zone and a bed of high particle density in the lower zone. (d) the hydraulic classification of the particles in the beds to perform the gravitational separation of the low and high density particles in the pulp causing the low density particles to migrate to and into the low density bed and causing them to migrate the high density particles towards and for inside the high density bed; (e) the removal of a fraction of concentrate containing low density particles from the upper portion of the column above the upper zone, (f) the removal of a washout fraction containing high density particles from the upper portion of the column. lower portion of the column by - below the lower area.