KALlNA, Andrey Vladimirovich (Apartment 14, 11 Bolshoi Sukharevskiy PereulokMoscow 1, RUSSIA, 12705, RU)
TABAKOV, Grigory Nikolaevich (Apartment 16 Building 2, 15 Ghristoprudniy Boulevard, Moscow 0, 10100, RU)
KUZMIN, Aleksandr, Vladimirovic (Apartment 110, 46 Pionerskiy ProspektNovokuznetsk 7, RUSSIA, 65400, RU)
KALlNA, Andrey Vladimirovich (Apartment 14, 11 Bolshoi Sukharevskiy PereulokMoscow 1, RUSSIA, 12705, RU)
TABAKOV, Grigory Nikolaevich (Apartment 16 Building 2, 15 Ghristoprudniy Boulevard, Moscow 0, 10100, RU)
| CLAIMS: Apparatus for pneumatic separation of loose materials including: a mesh conveyor for conveying the loose materials across a separation zone; a blower .nozzle assembly operatively aligned beneath the mesh conveyor and operable to blow gaseous medium .in a predominantly upward direction through the mesh conveyor and the loose materials thereon; a suction nozzle assembly operatively aligned above the mesh conveyor and in substantial alignment with the blower nozzle assembly, the suction nozzle assembly being operable to generate suction predominantly above the loose material and thereby receive the gaseous medium and a portion of the loose material entrained therein; separation means operatively associated with the suction nozzle assembly for separating the entrained loose material from the gaseous medium; and wherein each nozzle assembly is formed to provide an elongate fluidization area . in the direction of travel ol the conveyor through separation, zone. 2. The apparatus according to Claim 1, wherein the blower and suction nozzles are aligned with their respective axes intersecting a conveyor axis, the conveyor axis being aligned substantially in the direction of travel of the conveyor. 3. The apparatus according to Claim 2, wherein the blower no2Zle and suction nozzle are provided in pairs aligned along the conveyor axis. 4. · The apparatus according to any one of the preceding claims, wherein each pair of the blower nozzles and the suction nozzles are provided as a set of nozzles and a plurality of sets of nozzles are provided in spaced relationship to one another along the conveyer axis. 5. The apparatus according to Claim 3 or Claim 4 wherein the elongate fluidization area is subject to- the fluidization for an extended period under particular entrainment conditions to thereby fractionate the loose materials on the conveyor by virtue of their respective entrainment properties. 6- The apparatus according to Claim A or. Claim 5, _-n the flow rate of the gaseous medium is increased for each nozzle set downstream from the previous one. 7. A method of pneumatically separating loose materials including: conveying the loose materials on mesh conveyor across a separation zone; blowing a gaseous medium in a predominantly upward d rection from a blower nozzle assembly operatively aligned beneath the mesh conveyor through the mesh conveyor and the loose materials thereon; generating suction predominantly■ above the loose material in substantial alignment with the blower nozzle assembly by a suction nozzle assembly operatively aligned above the mesh conveyor; arranging each nozzle assembly whereby said .blowing and said suction are elongate in the direction of travel of the conveyor through separation . zone; receiving the gaseous medium and a portion of the loose material entrained therein into the suction nozzle assembly; and separating the entrained loose material from the gaseous medium. |
.FIELD OF INVENTION
THIS INVENTION relates to a pneumatic separation of loose materials. The invention has particular application to a method of and apparatus for dry pneumatic separation of rnulti.-component loose materials, such as coal and/or other ores. However, the invention is not linnted to this field of use and may be used in other fields where loose, predominantly solid materials of different compositions or properties arc in a mixed state and require separation from one another.
BACKGROUND ART
Dry beneficiation of coal in a fluidized bed is sometimes used as an alternative to- washing, particularly where water supply and/or wastewater disposal is a problem. Pneumatic separation has been disclosed by Falenko, T. G. , Butovitskiy, V. 3., Pogartseva, E. M. in ^'Technology of coal beneficiation: the Handbook" — 2 nd edition, published by Nedra, Moscow, 1985 ~ pages 93-96 and 136-144 and Tsiperovich, M. V. in "Equipment for coal washing plants" published by "Metaliurgizdat", Sverdlovsk, 1958 - pages 213-238. These publications disclose that pneumatic separation is ineffective in comparison with other methods of concentration and it is not suitable for materials with densities over 2,300 kg m -3 . However, dry pneumatic beneficial-ion has low productivity, process stability and reliability and has equipment which is complex and bulky,
Russian Patent Specification No. 2,282,503 discloses a method of beneficiabion of coal which is more efficient than previous systems, and discloses a method including the steps of preliminary crushing, selective grinding and classifying material in three stages by provision of a series of three suction nozzle ' s above the material on a conveyer. A first suction nozzle is spaced from the conveyor belt at a maximum distance; a second suction nozzle mounted at leaser distance from the belt as compared with first nozzle and a third nozzle is mounted at a minimum distance from belt.
The aforementioned Russian Patent discloses details of a mesh conveyor with three suction nozzles installed above it. However, material having a density over 1, 800 to 2, 500 kg m "5 remains on the mesh conveyor and is dumped to a reject bunker for further disposal. This method therefore does not allow separation of materials with density over 2, 500 kg m -3 . There is also a limit to the clearance of nozzles above the mesh conveyor due to possibility that the nozzles can obstruct and/or be struck by the material on the conveyor. There is also a requirement for powerful fans to be provided and the recovery of each fraction is low.
The present invention aims to provide a method of and apparatus for pneumatic separation of materials which alleviatesthe shortcomings of the prior art. Other aims and advantages of the invention may become apparent from the following description.
DISCLOSURE OF THE INVENTION With the foregoing in view, the present invention in one aspect resides broadly in apparatus for pneumatic separation of loose materials including:
a mesh conveyor for conveying the loose materials across a separation zone;
a blower nozzle assembly operatively aligned beneath the mesh conveyor and operable to blow gaseous medium in a predominantly upward direction through the mesh conveyor and the loose materials thereon;
a suction nozzle assembly operatively aligned above the mesh conveyor and in substantial alignment with the blower nozzle assembly, the suction nozzle assembly being operable to generate suction predominantly above the loose material and thereby receive the gaseous medium and a portion of the loose material entrained therein? and
separation means operatively associated with the suction nozzle assembly for separating the entrained loose material from the gaseous medium; and wherein
each nozzle assembly is formed to provide an elongate fluidizaLion area in the direction of travel of the conveyor through separation, zone.
In another aspect, the present invention resides broadly in a method of pneumat cally separating loose materials including: conveying the loose materials on mesh conveyor across a separation zone;
blowing a gaseous medium in a predominantly upward direcLion ■ from a blower . nozzle assembly operatively aligned beneath the mesh conveyor through the mesh conveyor and the loose materials thereon;
generating suction predominantly above the loose material in substantial alignment with the blower nozzle assembly by a suction nozzle assembly operatively aligned above the mesh conveyor;
arranging each, nozzle assembly whereby said blowing and said suction are elongate in the direction of travel of the conveyor through separation zone;
receiving the gaseous medium and a portion of the loose material entrained bherein into the suction nozzle assembly; and
separating the entrained loose material from the gaseous medium. The blower and suction nozzles are preferably aligned with their respective axes intersecting the axis of the direction of travel of the conveyor (the ^conveyor axis") . Preferably, there are two "or more blower nozzles and two or more suction nozzles provided in pairs, each member of the or each pair being aligned a]ong the conveyor axis. It is further preferred that each member of the pair be arranged in such proximity to one another that fluidization of the loose material on the conveyor above and between the blower nozzles is established and substantially maintained.
In such form, the blower nozzles and suction nozzles form a set of blower and suction nozzles. Each set of nozzles therefore provides an elongate fluidization area through which the material on the conveyor passes. The benefit of the elongate fluidization area is that the material is subject to the fluidization for an extended period under particular, entrainment conditions to thereby fractionate the particles by virtue of their respective entrainment properties.
The conveyor is arranged to convey the loose material substantially horizontally, but it will be appreciated that the conveyor may be arranged to convey the loose material up or down an incline small enough that the neither fluidization of the loose material nor bulk flow of the material along the conveyor are substantially adversely affected.
Preferably,, there is a plurality of blower and suction nozzle sets spaced along the conveyer axis. In such form, the flow rate of the gaseous medium is increased for each nozzle set downstream from the previous one. In a preferred form, there are three blower and suction nozzle sets. For example, the first set may be operated at a .flow rate to entrain loose material with a density of from 1,350 to 1, 600 kg m -3 . The loose material remaining on the conveyor may then be conveyed to pass between the second set of blower and suction nozzles which may be operated at a flow rate to entrain loose material with a density of from 2, 500 to 5,000 kg m "3 . The loose material remaining on the conveyor may then be conveyed to pass between the third set of blower and suction nozzles which may be operated at a flow rate to entrain loose material with a density of from 4,000 to 5, 000 kg m "3 . The gaseous medium is preferably air.
A preferred method includes preliminary screening at class +0-100 mm, crushing selected oversize materials down to +0-100 ram and processing on .the pneumatic classifier or on vibrating screen with separation of underslze +0-1 mm material and sizing +1-300 mm raar.er al on sieves into classes with subsequent mesh sizes ratio equal to ..1,7 ·*· 2.0 to divide the material .into classes having coarsest to finest particles ratio no more than 1.7 - 2.0. A further preferred method includes feeding material of each class onto a mesh conveyor, with three sets of paired blowing nozzles installed underneath the mesh ' conveyor and aligned opposite paired suction nozzles installed above the mesh conveyor. Preferably, there are screens disposed between each set of nozzles.
The method of dry pneumatic separation of the multi- component loose materials further includes providing an increasing entrainrnent force on the particles between each successive set of nozzles by installing the first set of nozzles at a selected disLance from the mesh conveyor and installing each subsequent set of nozzles at a closer distance from the mesh conveyor. The material ' coming through areas in between the sets of paired nozzles is separated on fractions with different densities. The material with ' lower densities is sucked into the first set of nozzles, then the material with higher densities is sucked into the second set of nozzles and the material with oven higher densities .i s sucked up into the third set of nozzles, while the material with highest densities is left on the mesh conveyor.
The pneumatic separation of the multi-component loose materials could be also controlled by providing variable speed drives for the fan motors and adjustment ' of the speed drives to adjust the suction and blowing power of each set of nozzles. In another aspect, the present invention resides broadly in a system for dry pneumatic separation of the multi-component loose materials including:
screening means for removing +100mm oversize material; crushing means for selective crushing oversize material down to 0 - 100 mm size;
a classifier means for remo~ _ng of undersize +0-1 mm material;
size sorting means for sorting material into classes having in each class the size of coarsest to the size of finest particles ratio no more than 1.7 - 2.0;
apparatus for dry pneumatic separation of the multn- component loose materials; material handling means for feeding, transporting and collection of, product material and reject material.
The apparatus for dry pneumatic separation- of the multi- component loose materials includes in a preferred form a mesh conveyor with feed . bunker and products/rejects bunkers; three sets of doubled blowing nozzles insbailed underneath the mesh conveyor and aligned opposite doubled suction nozzles installed above the mesh conveyor; screens between each pair of doubled nozzles; fans driven by motors with variable * speed drives; solid traps, air cyclones and air filters; control means to adjust distances between nozzles sets and mesh conveyor, the speed of mesh conveyor, speed of fans. For example, the flow rate of the gaseous medium may be selected to provide for recovering 60% of the recoverable material for each nozzle, whereupon the recovery of the recoverable material is 84%.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be more readily understood and put into practical effect, a preferred embodiment of the present invention will now described with reference to the following drawings, and wherein:
Fig. 1 is a schematic representation of pneumatic separation apparatus according to the invention;
Fig. 2 is a schematic representation of a section of the pneumatic separation apparatus of Fig. 1 through line A-A.
DETAILED DESCRIPTION OF THE DRAWINGS The pneumatic separation apparatus 10 shown in Figs. 1 and 2 includes a conveyor 11 mounted for rotation about a drive roller -.31 and an idler roller 32 in the direction of arrow 33. The conveyor is supported along the upper portion of its travel by four support rollers shown typically at 37, the support rollers being disposed beneath the conveyor with their upper extremities in substantial straight-line alignment with the upper extremities of the drive and idler rollers .
Loose material 34 is fed into a bunker 12 through its open top orifice. The bunker includes trails which direct tho loose material onto the conveyor at a feed end 35. A first blower assembly 16 is disposed below the conveyor and a corresponding first suction assembly 13 disposed above the first blower assembly spaced above the loose material. A second blower assembly 17 is disposed below the conveyor and a corresponding second suction assembly 14 disposed above the second blower assembly spaced above the loose material, the second blower and suction assemblies being spaced downstream from the first blower and suction assemblies in the direction of travel of the loose material on the conveyor indicated by arrow 36. In similar fashion, a third blower assembly 18 is disposed below the conveyor and a corresponding firsL suction assembly 15 disposed above the third blower assembly spaced above the loose material spaced downstream from the first and second blower and suction assemblies. When operating to perform the method according to the invention, the blowers blow air out from their nozzle orifices In the direction of arrows shown typically at 38. The corresponding suction assemblies extract Lhe air from above the loose material on the conveyor, but by virtue of their disposition above the corresponding blower assemblies, the air generally proceeds as indicated by the arrows shown typically at 39.
In order to avoid loss of air at positive pressure produced by the blower assemblies, a lower shield 40 is provided below the conveyor substantially sealing a pressure space 41 below the conveyor, in similar fashion, in order to avoid loss of suction at negative pressure produced by the suction assemblies, an upper shield 42 is provided above the conveyor substantially sealing a vacuum space 43 above the conveyor and the loose material being conveyed thereon. The suction assemblies are operated to substantially match or exceed the blowing capacity of the blower assemblies in order to provide an advantage of substantially eliminating loss coal fines because any leakage of the system draws air into the system.
It will be appreciated that the nature of the loose material changes as it passes between the successive sets of blower and suction assemblies, as indicated schematically by the different cross-hatching patterns at 34, 44, 45 and 46. The material being discharged in the direction of arrow 22 is predominantly depleted of light weight material extractable from the feedstock at 34.
The blower and suction assemblies each have substantially the same arrangement as that of the first set depicted in Fig. 2. A blower unit 24 blows air into a distribution chamber 47 which distributes the air through two blower transfer passages 48, each, one being in fluid communication with one of the pair of blower nozzles. In similar fashion to the blower assembly, a suction unit 21 extracts air from a reception chamber 49 which receives the air through two suction transfer passages 50, each one being in 'fluid communication with one of the pair of suction nozzles. However, a solid trap 9 and a cyclone 20 are interposed in the lluid path between the reception chamber and the suction unit. A trap inlet duct 51 provides the fluid connection between the reception chamber and the solid trap. A cyclone inlet duct 52 provides the fluid connection between the solids Lrap and the cyclone. A suction unit inlet duct 53 provides the fluid connection between the cyclone and the suction unit. Extracted air is passed through an air filter 21 for discharge in the direction of arrows 54. Material caught by the filter is discharged as shown by arrow 55.
Beneficiated solids trapped by the solids trap are discharged through a discharge port of the solids- trap as indicated by arrow 56. Beneficiated fines are discharged through the discharge port of the cyclone as indicated by arrow 57. The beneficiated solids and solids may be combined as shown at B or kept separate from one another if required.
. In order that the invention may be more readily -understood and put into practical effect / two experimental examples demonstrating a preferred embodiment of the present invention will now described:
Example 1 : A sample of coal from "Bungursky" open, pit of Novokuznetsk area of Kemerovo region, Russia with initial ash content of 22.5% was comminuted to provide loose material for beneficiation. The loose material was beneficiated in apparatus and by the method according to the present invention. The loose material was beneficiated into a concentrate with ash content of 9%, middlings with ash content of 25% and · tailings with ash content 75% by the method according to the present invention.
Example 2 : A sample of manganese ore of Durnovskoye deposit
Leninsk-Kuznetsk area of Kemerovo region, Russia with the initial grade of manganese of 8% was comminuted to provide loose material for beneficiation. The loose material was beneficiated into a concentrate with the grade of 32% by the method according to the invention.
In use, pneumatic separation apparatus according to the invention could be used in coal, mining, building, chemical,. metallurgical industries. The installation of blowing nozzles underneath the mesh conveyor aligned with suction nozzles opposed thereto improves the dry separation method by providing simultaneous blowing and suction force on material particles - Doubling each of nozzles at each stage of separation provides doubling of separation process. Screens are installed between each set of blowing and suction nozzlea for creation of directional air flows, increasing air supercharge in the blowing nozzles and air discharge in the suction nozzles up to the pressure of 2,000 - 3000 ram water column. It is believed that the method and apparatus of the present invention provides separation of multi-component materials with the densities up to 4,000 - 5,000 kg m ~3 with greater recovery for each fraction.
The feed material is subject to preliminary screening to produce material, of a size (class) of +0-100 mm. Oversize material greater than 100 mm is subject Lo size reduction or comminution down to class +0-100 mm. Then the material is processed on a pneumatic classifier or on a vibrating screen with separation of class +0-1 mm. The material +1-100 mm is screened on a sieve with the subsequent mesh sizes ratio equal 1.7 - 2.0 to divided material into classes having coarsest to finest particles ratio no more than 1.7-2.0.
After screening oversize material of each class is fed from the bunker 12 onto the inesh conveyor 11 providing a monolayer (Fig. 1) . In the area between the first suction nozzles 13 and blowing nozzles 16 up to 60¾ of the fraction with set up density is sucked up by the first of doubled mouths (a) and then up to 60·% of this fraction remained on the mesh conveyor is sucked up by the second of doubled mouth (b) . As a result the recovery of iraction with density between 1,250 - 1,350 kg irf 3 (1.25 - 1.35 SG)
Corresponding to suet.ion nozzles 13, 14 and 15, blowing nozzles 16, 17 and 18 increase the total speed of air passing through the loose material on the conveyor, and also allow the suction nozzles to be positioned with an operative clearance above the mesh, conveyor and substantially eliminate danger of collision of the loose material with mouths of suction nozzles.
The material which has passed between first set of nozzles
13 and 16 is transported further to pass between the second set of nozzles 14 and 17 which are set up closer to the mesh conveyor in order to provide- suction for the fraction of loose material with density 1,350 - 1,600 kg m "3 . The material which has passed between second set of nozzles.14 and 17 is transported further to pass between the third set of nozzles 15 and 18 which are set up closer again to the mesh conveyor in order to provide suction for the fraction of loose material with density 1,600 - 2,500 kg m ~3 . The material, which has remained on the mesh conveyor, having density between 2,500 - 5,000 kg m ~3 is dumped to the bunker for heavy materials 22. If it is required to divide a material in density range between 2,500 - 5,000 kg m -3 , the mesh conveyor could be supplied with additional one or two sets of nozzles. For an separation of heavy fractions with density up to 4,000 - 5,000 kg πι ~3 , air supercharge in the blowing nozzles 16, . 17 and 19 and air discharge in the suction nozzles 13, 14 and 15 is increased up to the rate of 2,000 - 3,000 mm water column.
Each fraction of the material (for example with density between 1,250 - 1,350 kg in" 3 is forced by the blowing nozzles 16 (Fig. 2) and simultaneously by the. suction nozzles 13. The sucked up material then goes in the solid trap 19 where . the coarser particles drop out of a stream? the finer particles and a dust, formed during processing, settle in an air cyclone 20. Products of separation of this fraction from ' solid trap 19, the air cyc ' lone 20 and the air filter 21 collected together (B) . If it is required the products from solid trap 19, the air cyclone 20 and Lhe air filter 21 could be discharged separately. Air flow In nobles is provided by fans 23 and 24. For creation of directional air flows between each pair of suction nozzles 13, 14 and .5 the screen 25 are installed and between each pair, of doubled blowing nozzles 16, 17 and 18 the screen 26 are installed. Those screens prevent air flows from interference and spreading before the mesh conveyor.
The proposed method provides separation of materials with the density up to 5,000 kg m -3 and the size of particles up to 100 mm with recovery of each fraction up to 84% » Those samples demonstrate' practicality of separation of multi-component 'loose materials by the proposed method.
Although the invention has been described with reference Lo a specific example, it will be appreciated that the invention may be embodied in other forms as would be apparent to those skilled in the art within the broad scope and ambit of the invention as herein set forth and defined by the following claims.
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