CA2378956A1 - Method for the preparation of fine grain ores - Google Patents
Method for the preparation of fine grain ores Download PDFInfo
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- CA2378956A1 CA2378956A1 CA 2378956 CA2378956A CA2378956A1 CA 2378956 A1 CA2378956 A1 CA 2378956A1 CA 2378956 CA2378956 CA 2378956 CA 2378956 A CA2378956 A CA 2378956A CA 2378956 A1 CA2378956 A1 CA 2378956A1
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- ultrafine
- classifier
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/2406—Binding; Briquetting ; Granulating pelletizing
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0033—In fluidised bed furnaces or apparatus containing a dispersion of the material
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/005—Separation by a physical processing technique only, e.g. by mechanical breaking
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Organic Chemistry (AREA)
- Metallurgy (AREA)
- Materials Engineering (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mechanical Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Geochemistry & Mineralogy (AREA)
- Dispersion Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Combined Means For Separation Of Solids (AREA)
- Separating Particles In Gases By Inertia (AREA)
- Electrostatic Separation (AREA)
Abstract
The invention concerns a method for the preparation of fine-grain ore (2) in which the ore (2) is subjected to wind screening using a gas. Two fractions are formed (6, 8): a crude fraction (6) and a primary fine fraction (8), whereby the crude fraction (6) is ejected (6) and the primary fine fraction (8) is carried along by the gas, then deposited out of the gas and at least the majority thereof this is processed together with the crude fraction (6). The primary fine fraction is subjected again to a wind screening (8) using a gas which results in the deposition of a secondary fine fraction (18) and is processed together with the crude fraction (6). An ultrafine fraction (19) i s carried along with the gas and then deposited out of the gas. In the subsequent processing steps which the fine grain ore (2) is subjected to, caking and sticking which can be caused by the ultra-fine fraction (19), can be avoided.
Description
Method for the preparation of fine grain ores The present invention relates to a process for the beneficiation of fine-grained ore, they ore being subjected to gas classification by means of a gas, in which classification two fractions are formed, namely a coarse fraction and a first fine fraction, the coarse fraction being separated out and the first fine fraction being entrained with the gas, then separated out of the gas and at least for the most pert being fed for processing together with the coarse fraction, and to an installation for carrying out the process.
In fluidized-bed processes, for example those used for the direct reduction of fine-grained ore, cyclones are used to separate out and recycle the material which is discharged with the fluidizing gas. ThES separation capacity, i.e. the efficiency and the separation grain size of the cyclones, is adversely affected by the formation of caking and adhesion in the cyclone, with the result that more material is discharc3ed from the fluidized-bed reactor together with the fluidizing gas.
In the case of direct reduction of fine-grained ore, for example iron ore, it is primarily at least partially reduced fine ore dust which causes this caking and adhesion. The resulting increased discharge of material either has to be recorded as a loss or, in the case of multistage processes carried out in downstream fluidized-bed reactors, causes problems by blocking the holes in the distributor ba;~es of these fluidized-bed reactors.
The fine dust which causes these problems is formed firstly through mechanical abrasion of i=he material which is to be reduced in the fluidized-bec: process and secondly by being introduced with the charge material.
Particularly when using fine iron ores, the proportion of so-called adhesion and fine grains presents a problem. On the one hand, this material is involved in the formation of caking and adhesion, anc3 secondly it is discharged from the system and lost.
To dry fine iron ores, it is the state of the art to use fluidized-bed dryers by means of which the charge material is simultaneously separated into a coarse fraction and a fine fraction. These material flows are used to set the charge grain size in a controlled way.
A process of this type is known, for Example, from AT-B-400 578. In this known process, fine ore is dried with the aid of a hot drying gas which flows around the ore particles of the fine ore, and the drying gas, after it has flowed around the ore particles, is cleaned, with entrained ore dust pari~icles being removed. The ore dust particles are collected and are admixed with the dried fine ore. The drying takes place at the same time as gas classification of the fine ore in the fluidized-bed process, the drying gas being passed through the fine ore to form a fl.uidized bed, and the velocity of the drying gas being seat at a level at which ore dust particles which are smaller than a preselected size are entrained. The ore dust particles entrained by the drying gas are separated out, collected and admixed to the dried fine ore in metered quantities. When using the ore which has been treated in this way in a fluidized-bed direct reduction process, the fine ore may under certain circumstances cause problems by, in an at least partially reduced state, leading to caking and adhesion in trLe fluidized-bed reactor.
US-A-3 917 480 has disclosed a process for the beneficiation of particulate material for use in fluidized-bed reactors, in which, in a first process step, 20-70% of the fine fraction of the material is separated out and the remaining fraction is introduced into a fluidized bed, a further fine fr~~ction being separated out in the fluidized bed, di;~charged and admixed with the fine fraction obtained in the first process step. The fine fractions are pelletized and added to the fluidized bed. A drawback of this process is that at least a not inconsiderable fine fraction enters the fluidized bed, where it can caL~.se the above-mentioned problems, such as adhesion and c;~king.
DE-A-197 11 629 shows a process for the pretreatment of fine ores having a wide grain size range for direct reduction as known, in which the fine ores belonging to the grain size fraction of less than 6.3 mm and preferably less than 3 mm are dried by means of a hot-air or flue-gas flow during a pneumatic conveying operation, if appropriate with the moist material being recycled, the 6.3 mm or 3 mm down to approx. 0.04 mm fraction being screened out of the dried fine ore and being fed for direct reduction. The fine ore fraction of a size which is smaller than approx. 0.04 mm and is discharged from the cyclone connected down:~tream of the dryer together with the drying air or t:he flue gas, passes for ultrafine separation into a multicyclone.
The fine ore which is separated out there is fed to a pelletizing device and is shaped into pellets, with water and binder being supplied, these pellets ultimately being added to the dryer via. a delivery device. The multicyclone which is provided for the ultrafine separation is an extremely complex apparatus.
The present invention is based on the object of providing a process for the beneficiation of fine-grained ore and an installation for carrying out the process, according to which the ore is ber..eficiated in such a manner that, when the ore is subsequently used in a fluidized-bed reactor, the abovementioned problems, such as caking and adhesion in a cyclone and a fluidized-bed reactor, are avoided. The process should in particular be easy to carry out u~~ithout major outlay on equipment.
In fluidized-bed processes, for example those used for the direct reduction of fine-grained ore, cyclones are used to separate out and recycle the material which is discharged with the fluidizing gas. ThES separation capacity, i.e. the efficiency and the separation grain size of the cyclones, is adversely affected by the formation of caking and adhesion in the cyclone, with the result that more material is discharc3ed from the fluidized-bed reactor together with the fluidizing gas.
In the case of direct reduction of fine-grained ore, for example iron ore, it is primarily at least partially reduced fine ore dust which causes this caking and adhesion. The resulting increased discharge of material either has to be recorded as a loss or, in the case of multistage processes carried out in downstream fluidized-bed reactors, causes problems by blocking the holes in the distributor ba;~es of these fluidized-bed reactors.
The fine dust which causes these problems is formed firstly through mechanical abrasion of i=he material which is to be reduced in the fluidized-bec: process and secondly by being introduced with the charge material.
Particularly when using fine iron ores, the proportion of so-called adhesion and fine grains presents a problem. On the one hand, this material is involved in the formation of caking and adhesion, anc3 secondly it is discharged from the system and lost.
To dry fine iron ores, it is the state of the art to use fluidized-bed dryers by means of which the charge material is simultaneously separated into a coarse fraction and a fine fraction. These material flows are used to set the charge grain size in a controlled way.
A process of this type is known, for Example, from AT-B-400 578. In this known process, fine ore is dried with the aid of a hot drying gas which flows around the ore particles of the fine ore, and the drying gas, after it has flowed around the ore particles, is cleaned, with entrained ore dust pari~icles being removed. The ore dust particles are collected and are admixed with the dried fine ore. The drying takes place at the same time as gas classification of the fine ore in the fluidized-bed process, the drying gas being passed through the fine ore to form a fl.uidized bed, and the velocity of the drying gas being seat at a level at which ore dust particles which are smaller than a preselected size are entrained. The ore dust particles entrained by the drying gas are separated out, collected and admixed to the dried fine ore in metered quantities. When using the ore which has been treated in this way in a fluidized-bed direct reduction process, the fine ore may under certain circumstances cause problems by, in an at least partially reduced state, leading to caking and adhesion in trLe fluidized-bed reactor.
US-A-3 917 480 has disclosed a process for the beneficiation of particulate material for use in fluidized-bed reactors, in which, in a first process step, 20-70% of the fine fraction of the material is separated out and the remaining fraction is introduced into a fluidized bed, a further fine fr~~ction being separated out in the fluidized bed, di;~charged and admixed with the fine fraction obtained in the first process step. The fine fractions are pelletized and added to the fluidized bed. A drawback of this process is that at least a not inconsiderable fine fraction enters the fluidized bed, where it can caL~.se the above-mentioned problems, such as adhesion and c;~king.
DE-A-197 11 629 shows a process for the pretreatment of fine ores having a wide grain size range for direct reduction as known, in which the fine ores belonging to the grain size fraction of less than 6.3 mm and preferably less than 3 mm are dried by means of a hot-air or flue-gas flow during a pneumatic conveying operation, if appropriate with the moist material being recycled, the 6.3 mm or 3 mm down to approx. 0.04 mm fraction being screened out of the dried fine ore and being fed for direct reduction. The fine ore fraction of a size which is smaller than approx. 0.04 mm and is discharged from the cyclone connected down:~tream of the dryer together with the drying air or t:he flue gas, passes for ultrafine separation into a multicyclone.
The fine ore which is separated out there is fed to a pelletizing device and is shaped into pellets, with water and binder being supplied, these pellets ultimately being added to the dryer via. a delivery device. The multicyclone which is provided for the ultrafine separation is an extremely complex apparatus.
The present invention is based on the object of providing a process for the beneficiation of fine-grained ore and an installation for carrying out the process, according to which the ore is ber..eficiated in such a manner that, when the ore is subsequently used in a fluidized-bed reactor, the abovementioned problems, such as caking and adhesion in a cyclone and a fluidized-bed reactor, are avoided. The process should in particular be easy to carry out u~~ithout major outlay on equipment.
According to the invention, this object is achieved, in a process of the type described in the introduction, by the fact that the first fine fraction is subjected to a further gas classification by means of a c_~as, in which a second fine fraction and an ultrafine fraction are formed, and the second fine fraction is fed for processing together with the coarse fraction and the ultrafine fraction is entrained with the gas and is then separated out of the gas.
The invention is based on the discovery that the ultrafine fraction of the ore, in tr.e at least partially reduced state, is principally re;~ponsible for caking and adhesion in fluidized-bed reactors.
Furthermore, it has been discovered that triis ultrafine fraction adheres to the first fine fracti~an, which is separated from the charge material by means of the first gas classification. After reduction, i.e. in the at least partially reduced state, during the processing of the second fine fraction together with the coarse fraction, the ultrafine fraction, as is known, for example, from the abovementioned AT-B-400 578, causes the abovementioned problems in the fluidized-bed reactor. According to the invention, this is avoided by separating the ultrafine fraction out of the first fine fraction.
Preferably, the ultrafine fraction which has been separated out of the gas is admixed with a binder, granulated and fed for processing or discharged. In the case of granulation and further procESSSing, the ultrafine fraction is advantageously not lost to further processes.
Expediently, granules which are formed from the ultrafine fraction are processed further together with the coarse fraction and the second fine fraction. By way of example, the further processing involves direct reduction downstream of the ore beneficiaticn.
The invention is based on the discovery that the ultrafine fraction of the ore, in tr.e at least partially reduced state, is principally re;~ponsible for caking and adhesion in fluidized-bed reactors.
Furthermore, it has been discovered that triis ultrafine fraction adheres to the first fine fracti~an, which is separated from the charge material by means of the first gas classification. After reduction, i.e. in the at least partially reduced state, during the processing of the second fine fraction together with the coarse fraction, the ultrafine fraction, as is known, for example, from the abovementioned AT-B-400 578, causes the abovementioned problems in the fluidized-bed reactor. According to the invention, this is avoided by separating the ultrafine fraction out of the first fine fraction.
Preferably, the ultrafine fraction which has been separated out of the gas is admixed with a binder, granulated and fed for processing or discharged. In the case of granulation and further procESSSing, the ultrafine fraction is advantageously not lost to further processes.
Expediently, granules which are formed from the ultrafine fraction are processed further together with the coarse fraction and the second fine fraction. By way of example, the further processing involves direct reduction downstream of the ore beneficiaticn.
However, according to a further preferred embodiment, granules which are formed from the ultra.fine fraction can also be admixed with the fine-grained ore which is to be subjected to the first gas classification.
Expediently, gas from which the entrained ultrafine fraction has been removed is subjected to further cleaning, in which an extremely ultrafins: fraction is separated out, and this fraction, preferably together with the ultrafine fraction, is granulated and fed for processing or discharged. As a result, it is also possible to substantially utilize the dust fractions which are still present in the gas after the ultrafine fraction has been separated out.
According to a preferred embodiment, at least a partial quantity of the second fine fraction is likewise granulated, preferably together with the ultrafine fraction and/or extremely ultrafine fraction. In this way, problems with caking and adhesion of ore in dust form in subsequent processes are particul;~rly reliably avoided.
In the process according to the invention, the first fine fraction is separated out of the fin.=-grained ore by means of the first gas classification preferably with a particle size of up to 150 ~zm, and the ultrafine fraction is separated out of the first fine fraction with a particle size of up to 20 um by means of the further gas classification.
According to a preferred embodiment of the process according to the invention, a drying gay is used at least in the first gas classification. In this case, drying takes place at the same time as the gas classification of the charge material.
The binder used for the granulation is advantageously calcined lime or bentonite.
Expediently, gas from which the entrained ultrafine fraction has been removed is subjected to further cleaning, in which an extremely ultrafins: fraction is separated out, and this fraction, preferably together with the ultrafine fraction, is granulated and fed for processing or discharged. As a result, it is also possible to substantially utilize the dust fractions which are still present in the gas after the ultrafine fraction has been separated out.
According to a preferred embodiment, at least a partial quantity of the second fine fraction is likewise granulated, preferably together with the ultrafine fraction and/or extremely ultrafine fraction. In this way, problems with caking and adhesion of ore in dust form in subsequent processes are particul;~rly reliably avoided.
In the process according to the invention, the first fine fraction is separated out of the fin.=-grained ore by means of the first gas classification preferably with a particle size of up to 150 ~zm, and the ultrafine fraction is separated out of the first fine fraction with a particle size of up to 20 um by means of the further gas classification.
According to a preferred embodiment of the process according to the invention, a drying gay is used at least in the first gas classification. In this case, drying takes place at the same time as the gas classification of the charge material.
The binder used for the granulation is advantageously calcined lime or bentonite.
Preferably, gas which is used in th~~ first gas classification and from which the first Fine fraction has been removed is used for the further gas classification.
An installation for carrying out the process according to the invention, having a first gas classifier, provided with a feed for fine-grained ore, a gas feed line, an outlet line for a coarse fraction and an outlet line for gas and a first fine fraction entrained with the gas, and having a first gas-cleaning device which is connected downstream of the first gas classifier and separates the first fine fr<~ction out of the gas, is characterized in that an outlet line for the f first f fine fraction leading out of the f first gas-cleaning device has a line connection to a further gas classifier, which has a gas feed line, an outlet line for a second fine fraction and an outlet line for gas and an ultrafine fraction entrained with the gas, and in that a second gas-cleaning device, which separates the ultrafine fraction out of the gas, is connected downstream of the further gas classifier.
Preferably, an outlet line for the ultrafine fraction leading out of the second gas-cleaning device has a line connection to a granulation apparatus, a feed line for a binder opening into the granulation a;oparatus.
According to a further preferred embodiment, the granulation apparatus has a line connection to the feed for feeding fine-grained ore to the first gas classifier.
Advantageously, a common discharge apparatus is provided for the coarse fraction, the second fine fraction and the ultrafine fraction which is subjected to granulation.
_ 7 _ The gas-cleaning devices are expediently designed as cyclones.
Preferably, a further gas-cleaning device for separating out an extremely ultrafine frG.ction, which is entrained with the gas, is connected downstream of the second gas-cleaning device, an outlet line for the extremely ultrafine fraction leading out of. the further gas-cleaning device having a line connection to a granulation apparatus.
According to a further preferred embodiment of the installation according to the invention, the outlet line for the second fine fraction leading out of the further gas classifier has a line connection to a granulation apparatus.
Expediently, at least the first gas c:_assifier is designed as a dryer, a feed line for drying gas opening into the gas classifier.
Advantageously, a gas outlet line leading out of the first gas-cleaning device has a line connection to the gas feed line leading to the further gas cl;~ssifier.
The invention is explained in more detai7_ below with reference to the drawing and on the basis of an exemplary embodiment. The figure diagrammatically depicts a flow diagram for a preferred e~:nbodiment of the invention.
The figure illustrates a gas classifier 1, which is designed as a fluidized-bed unit and into which fine-grained ore 2 is introduced via a feed 3. The fine-grained ore 2, which forms a bed 4 in the gas classifier 1, is fluidized and subjected to gas classification by means of a gas supplied via a feed line 5. In the process, it is separated into a coarse fraction 6, which is discharged via an outlet line 7, and a first fine fraction 8, which is entrained with the gas.
In the exemplary embodiment shown, the fine-grained ore 2 used has a grain size of from 0 to 12 mm. It is separated into the coarse fraction 6, with a grain size of from 0.15 to 12 mm, and the first fine fraction 8, with a grain size of from 0 to 0.15 mm, by gas classification. The gas used is a drying gas, the fine-grained ore 2 being subjected to drying as well as gas classification.
The coarse fraction 6 which is discharged via the outlet line 7 is applied to a discharge: apparatus, which is designed as a conveyor belt 9, and is fed for further processing, for example direct reduction. The first fine fraction 8 is discharged from the gas classifier 1 together with the gas via an outlet line 10 and is separated out of the gas. An impingement separator 11 and a cyclone 12 are used for this purpose. The fine fraction 8 which has bean separated out passes into a storage hopper 13 and, from there, via a line 14, into a further gas classifier 15, which is likewise designed as a fluidized-bed unit. In the further gas classifier 15, the first fine' fraction 8 forms a bed 16. The gas used is gas from which the first fine fraction 8 has been removed by means of the cyclone 12 and which is supplied via a feed line 17.
In the further gas classifier 15, the first fine fraction 8, with a grain size of from 0 to 0.15 mm, is separated into a second fine fraction 18, with a grain size of from 20 to 150 um, and an ultrafine fraction 19, with a grain size of from 0 to 20 um. The second fine fraction 18 is discharged from the further gas classifier 15 via an outlet line 20, i;~ applied to the conveyor belt 9 and is fed for further processing together with the coarse fraction 6.
_ g _ The gas and the ultrafine fraction 19 which is entrained with the gas are discharged from the further gas classifier 15 via an outlet line 21. ,The gas is cleaned by means of a cyclone 22, in which the ultrafine fraction 19 is separated out.
The ultrafine fraction 19 passes into a storage hopper 23 and, from there, to a granulation apparatus 24. A feed line 25 for a b:_nder 26 for granulating the ultrafine fraction 19 opens into the granulation apparatus 24. The binder 26 used in the exemplary embodiment shown is calcined lime or bentonite.
The ultrafine fraction 19 is granulatE~d to form granules 27 with a grain size of from 0.5 to 4 mm, and the granules 27 are likewise applied to the conveyor belt 9. They are fed for further processing together with the coarse fraction 6 and the second fine fraction 18.
However, it is also possible for the granules 27 to be fed to the first gas classifier 1 via a line (not shown in more detail in the figure) and to be introduced into this classifier together with the fine-grained ore 2.
According to a further preferred embodiment, the ultrafine fraction 19 is not fed to the granulation apparatus 24 but rather, as indicated by dashed line 28 in the figure, is discharged and fed, for example, for landfill. The advantage of this variant is that the step of granulating the ultrafine fraction 19, which in quantitative terms forms a relatively small proportion of the overall charge of fine-grained ore 2, is dispensed with, yet at the same time the ultrafine fraction 19 is prevented from causing disruption in subsequent processing steps, in particular from causing caking and adhesion. The small quantity of charge material lost is of only subordinate imporvance if ore - 1~ -prices are low.
In the exemplary embodiment shown, the gas which has been cleaned by means of the cyclone 22 is fed to a further gas-cleaning device 29 which may, for example, be an electrostatic filter. By means of the further gas-cleaning device 29, an extremel~r ultrafine fraction 30, which is still entrainf~d following cleaning in the cyclone 22, is separated out of the gas and is likewise fed to the granulation apparatus 24 and granulated together with the ultrafine fraction 19.
However, it is also equally possible for i~he extremely ultrafine fraction 30 to be discharged and landfilled, as indicated by dashed line 28 in the figure.
The second fine fraction 18 which is di:>charged from the second gas classifier 15 and is not entrained with the gas can at least in part be fed, via a line 31 which is indicated in dashed lines in the figure, to the granulation apparatus 24, where it i.s granulated together with the ultrafine fraction 19 and the extremely ultrafine fraction 30 and is fed for further processing.
The invention is to be explained in even mere detail on the basis of the following exemplary embodiment:
Fine-grained ore 2 with a grain size of from 0 to 12 mm, which represents 100% of the charge material, is introduced into the first gas classifier 1 and is separated into a coarse fraction 6, with a grain size of from 0.15 to 12 mm, and a first fine' fraction 8, with a grain size of from 0 to 0.15 mm. The coarse fraction 6 makes up 67% of the charge.
The first fine fraction, which makes u~ 33% of the charge, is introduced into the further gas classifier 15 and is separated into a second fine fraction 18, with a grain size of from ~;0 to 150 um, and an ultrafine fraction 19, with a grain size of from 0 to 20 um. The second fine fraction 18 makes up 29% of the fine-grained ore 2 which is used, and t:he ultrafine fraction 19 makes up 4% of the charge material.
Electrostatic filters are used to separate an extremely ultrafine fraction 30 with a grain size of up to 1 um out of the gas from which the ultrafine fraction 19 has been removed.
The invention is not restricted to th.e exemplary embodiment given above. Naturally, there is considerable scope for variations with regard to the grain size of the material used and with regard to the grain size of the fractions which are separated out and their quantitative proportions in the material used.
An installation for carrying out the process according to the invention, having a first gas classifier, provided with a feed for fine-grained ore, a gas feed line, an outlet line for a coarse fraction and an outlet line for gas and a first fine fraction entrained with the gas, and having a first gas-cleaning device which is connected downstream of the first gas classifier and separates the first fine fr<~ction out of the gas, is characterized in that an outlet line for the f first f fine fraction leading out of the f first gas-cleaning device has a line connection to a further gas classifier, which has a gas feed line, an outlet line for a second fine fraction and an outlet line for gas and an ultrafine fraction entrained with the gas, and in that a second gas-cleaning device, which separates the ultrafine fraction out of the gas, is connected downstream of the further gas classifier.
Preferably, an outlet line for the ultrafine fraction leading out of the second gas-cleaning device has a line connection to a granulation apparatus, a feed line for a binder opening into the granulation a;oparatus.
According to a further preferred embodiment, the granulation apparatus has a line connection to the feed for feeding fine-grained ore to the first gas classifier.
Advantageously, a common discharge apparatus is provided for the coarse fraction, the second fine fraction and the ultrafine fraction which is subjected to granulation.
_ 7 _ The gas-cleaning devices are expediently designed as cyclones.
Preferably, a further gas-cleaning device for separating out an extremely ultrafine frG.ction, which is entrained with the gas, is connected downstream of the second gas-cleaning device, an outlet line for the extremely ultrafine fraction leading out of. the further gas-cleaning device having a line connection to a granulation apparatus.
According to a further preferred embodiment of the installation according to the invention, the outlet line for the second fine fraction leading out of the further gas classifier has a line connection to a granulation apparatus.
Expediently, at least the first gas c:_assifier is designed as a dryer, a feed line for drying gas opening into the gas classifier.
Advantageously, a gas outlet line leading out of the first gas-cleaning device has a line connection to the gas feed line leading to the further gas cl;~ssifier.
The invention is explained in more detai7_ below with reference to the drawing and on the basis of an exemplary embodiment. The figure diagrammatically depicts a flow diagram for a preferred e~:nbodiment of the invention.
The figure illustrates a gas classifier 1, which is designed as a fluidized-bed unit and into which fine-grained ore 2 is introduced via a feed 3. The fine-grained ore 2, which forms a bed 4 in the gas classifier 1, is fluidized and subjected to gas classification by means of a gas supplied via a feed line 5. In the process, it is separated into a coarse fraction 6, which is discharged via an outlet line 7, and a first fine fraction 8, which is entrained with the gas.
In the exemplary embodiment shown, the fine-grained ore 2 used has a grain size of from 0 to 12 mm. It is separated into the coarse fraction 6, with a grain size of from 0.15 to 12 mm, and the first fine fraction 8, with a grain size of from 0 to 0.15 mm, by gas classification. The gas used is a drying gas, the fine-grained ore 2 being subjected to drying as well as gas classification.
The coarse fraction 6 which is discharged via the outlet line 7 is applied to a discharge: apparatus, which is designed as a conveyor belt 9, and is fed for further processing, for example direct reduction. The first fine fraction 8 is discharged from the gas classifier 1 together with the gas via an outlet line 10 and is separated out of the gas. An impingement separator 11 and a cyclone 12 are used for this purpose. The fine fraction 8 which has bean separated out passes into a storage hopper 13 and, from there, via a line 14, into a further gas classifier 15, which is likewise designed as a fluidized-bed unit. In the further gas classifier 15, the first fine' fraction 8 forms a bed 16. The gas used is gas from which the first fine fraction 8 has been removed by means of the cyclone 12 and which is supplied via a feed line 17.
In the further gas classifier 15, the first fine fraction 8, with a grain size of from 0 to 0.15 mm, is separated into a second fine fraction 18, with a grain size of from 20 to 150 um, and an ultrafine fraction 19, with a grain size of from 0 to 20 um. The second fine fraction 18 is discharged from the further gas classifier 15 via an outlet line 20, i;~ applied to the conveyor belt 9 and is fed for further processing together with the coarse fraction 6.
_ g _ The gas and the ultrafine fraction 19 which is entrained with the gas are discharged from the further gas classifier 15 via an outlet line 21. ,The gas is cleaned by means of a cyclone 22, in which the ultrafine fraction 19 is separated out.
The ultrafine fraction 19 passes into a storage hopper 23 and, from there, to a granulation apparatus 24. A feed line 25 for a b:_nder 26 for granulating the ultrafine fraction 19 opens into the granulation apparatus 24. The binder 26 used in the exemplary embodiment shown is calcined lime or bentonite.
The ultrafine fraction 19 is granulatE~d to form granules 27 with a grain size of from 0.5 to 4 mm, and the granules 27 are likewise applied to the conveyor belt 9. They are fed for further processing together with the coarse fraction 6 and the second fine fraction 18.
However, it is also possible for the granules 27 to be fed to the first gas classifier 1 via a line (not shown in more detail in the figure) and to be introduced into this classifier together with the fine-grained ore 2.
According to a further preferred embodiment, the ultrafine fraction 19 is not fed to the granulation apparatus 24 but rather, as indicated by dashed line 28 in the figure, is discharged and fed, for example, for landfill. The advantage of this variant is that the step of granulating the ultrafine fraction 19, which in quantitative terms forms a relatively small proportion of the overall charge of fine-grained ore 2, is dispensed with, yet at the same time the ultrafine fraction 19 is prevented from causing disruption in subsequent processing steps, in particular from causing caking and adhesion. The small quantity of charge material lost is of only subordinate imporvance if ore - 1~ -prices are low.
In the exemplary embodiment shown, the gas which has been cleaned by means of the cyclone 22 is fed to a further gas-cleaning device 29 which may, for example, be an electrostatic filter. By means of the further gas-cleaning device 29, an extremel~r ultrafine fraction 30, which is still entrainf~d following cleaning in the cyclone 22, is separated out of the gas and is likewise fed to the granulation apparatus 24 and granulated together with the ultrafine fraction 19.
However, it is also equally possible for i~he extremely ultrafine fraction 30 to be discharged and landfilled, as indicated by dashed line 28 in the figure.
The second fine fraction 18 which is di:>charged from the second gas classifier 15 and is not entrained with the gas can at least in part be fed, via a line 31 which is indicated in dashed lines in the figure, to the granulation apparatus 24, where it i.s granulated together with the ultrafine fraction 19 and the extremely ultrafine fraction 30 and is fed for further processing.
The invention is to be explained in even mere detail on the basis of the following exemplary embodiment:
Fine-grained ore 2 with a grain size of from 0 to 12 mm, which represents 100% of the charge material, is introduced into the first gas classifier 1 and is separated into a coarse fraction 6, with a grain size of from 0.15 to 12 mm, and a first fine' fraction 8, with a grain size of from 0 to 0.15 mm. The coarse fraction 6 makes up 67% of the charge.
The first fine fraction, which makes u~ 33% of the charge, is introduced into the further gas classifier 15 and is separated into a second fine fraction 18, with a grain size of from ~;0 to 150 um, and an ultrafine fraction 19, with a grain size of from 0 to 20 um. The second fine fraction 18 makes up 29% of the fine-grained ore 2 which is used, and t:he ultrafine fraction 19 makes up 4% of the charge material.
Electrostatic filters are used to separate an extremely ultrafine fraction 30 with a grain size of up to 1 um out of the gas from which the ultrafine fraction 19 has been removed.
The invention is not restricted to th.e exemplary embodiment given above. Naturally, there is considerable scope for variations with regard to the grain size of the material used and with regard to the grain size of the fractions which are separated out and their quantitative proportions in the material used.
Claims (19)
1. A process for the beneficiation of fine-grained ore (2), the ore (2) being subjected to gas classification by means of a gas, in which classification two fractions (6, 8) are formed, namely a coarse fraction (6) and a first fine fraction (8), the coarse fraction (6) being separated out and the first fine fraction (8) being entrained with the gas, then separated out of the gas and at least for the most part being fed for processing together with the coarse fraction (6), characterized in that the first fine fraction (8) is subjected to a further gas classification by means of a gas, in which a second fine fraction (18) and an ultrafine fraction (19) are formed, and the second fine fraction (18) is fed for processing together with the coarse fraction (6) and the ultrafine fraction (19) is entrained with the gas and is then separated out of the gas.
2. The process as claimed in claim 1, characterized in that the ultrafine fraction (19) which has been separated out of the gas is admixed with a binder (26) while being granulated, and is fed for processing or is discharged.
3. The process as claimed in claim 2, characterized in that granules (27) which are formed from the ultrafine fraction (19) are processed further together with the coarse fraction (6) and the second fine fraction (18).
4. The process as claimed in claim 2, characterized in that granules (27) which are formed from the ultrafine fraction (19) are admixed with the fine-grained ore (2) which is to be subjected to the first gas classification.
5. The process as claimed in one of claims 1 to 4, characterized in that gas from which the entrained ultrafine fraction (19) has been removed is subjected to further cleaning, in which an extremely ultrafine fraction (30) is separated out, and this fraction, preferably together with the ultrafine fraction (19), is granulated and fed for processing or discharged.
6. The process as claimed in one of claims 1 to 5, characterized in that at least a partial quantity of the second fine fraction (18) is likewise granulated, preferably together with the ultrafine fraction (19) and/or extremely ultrafine fraction (30).
7. The process as claimed in one of claims 1 to 6, characterized in that the first fine fraction (8) is separated out of the fine-grained ore (2) by means of the first gas classification with a particle size of up to 150 µm, and the ultrafine fraction (19) is separated out of the first fine fraction (8) with a particle size of up to 20 µm by means of the further gas classification.
8. The process as claimed in one of claims 1 to 7, characterized in that a drying gas is used at least in the first gas classification.
9. The process as claimed in one of claims 2 to 8, characterized in that calcined lime or bentonite is used as binder (26) for the granulation.
10. The process as claimed in one of claims 1 to 9, characterized in that gas which is used in the first gas classification and from which the first fine fraction (8) has been removed is used for the further gas classification.
11. An installation for carrying out the process as claimed in one of claims 1 to 10, having a first gas classifier (1), provided with a feed (3) for fine-grained ore (2), a gas feed line (5), an outlet line (7) for a coarse fraction (6) and an outlet line (10) for gas and a first fine fraction (8) entrained with the gas, and having a first gas-cleaning device (11, 12) which is connected downstream of the first gas classifier (1) and separates the first fine fraction (8) out of the gas, characterized in that an outlet line (14) for the first fine fraction (8) leading out of the first gas-cleaning device (11, 12) has a line connection to a further gas classifier (15), which has a gas feed line (17), an outlet line (20) for a second fine fraction (18) and an outlet line for gas and an ultrafine fraction (19) entrained with the gas, and in that a second gas-cleaning device (22), which separates the ultrafine fraction (19) out of the gas, is connected downstream of the further gas classifier (15).
12. The installation as claimed in claim 11, characterized in that an outlet line for the ultrafine fraction (19) leading out of the second gas-cleaning device (22) has a line connection to a granulation apparatus (24), a feed line (25) for a binder (26) opening into the granulation apparatus (24).
13. The installation as claimed in claim 12, characterized in that the granulation apparatus (24) has a line connection to the feed (3) for feeding fine-grained ore (2) to the first gas classifier (1).
14. The installation as claimed in claim 12 or 13, characterized in that a common discharge apparatus (9) is provided for the coarse fraction (6), the second fine fraction (18) and the ultrafine fraction (18) which is subjected to granulation.
15. The installation as claimed in one of claims 11 to 14, characterized in that the gas-cleaning devices are designed as cyclones (12, 22).
16. The installation as claimed in one of claims 11 to 15, characterized in that a further gas-cleaning device (29) for separating out an extremely ultrafine fraction (30), which is entrained with the gas, is connected downstream the second gas-cleaning device (22), an outlet line for the extremely ultrafine fraction (30) leading out of the further gas-cleaning device (29) having a line connection to a granulation apparatus (24).
17. The installation as claimed in one of claims 11 to 16, characterized in that the outlet line (20) for the second fine fraction (18) leading out of the further gas classifier (15) has a line connection (31) to a granulation apparatus (24).
18. The installation as claimed in one of claims 11 to 17, characterized in that at least the first gas classifier (1) is designed as a dryer, a feed line (5) for drying gas opening into the gas classifier (1).
19. The installation as claimed in one of claims 11 to 18, characterized in that a gas outlet line leading out of the first gas-cleaning device (11, 12) has a line connection to the gas feed line (17) leading to the further gas classifier (15).
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ATA1300/99 | 1999-07-27 | ||
| AT0130099A AT407346B (en) | 1999-07-27 | 1999-07-27 | METHOD FOR PROCESSING FINE-GRAIN ORE |
| PCT/EP2000/005565 WO2001007670A1 (en) | 1999-07-27 | 2000-06-16 | Method for the preparation of fine grain ores |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2378956A1 true CA2378956A1 (en) | 2001-02-01 |
Family
ID=3510913
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2378956 Abandoned CA2378956A1 (en) | 1999-07-27 | 2000-06-16 | Method for the preparation of fine grain ores |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP1204773A1 (en) |
| JP (1) | JP2003505240A (en) |
| KR (1) | KR20020016918A (en) |
| AT (1) | AT407346B (en) |
| AU (1) | AU5682600A (en) |
| CA (1) | CA2378956A1 (en) |
| MX (1) | MXPA02000629A (en) |
| WO (1) | WO2001007670A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3026129A4 (en) * | 2013-07-25 | 2017-03-08 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Method for manufacturing briquettes and reduced iron |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007216171A (en) * | 2006-02-17 | 2007-08-30 | Meiji Univ | Apparatus and method for separating powder |
| CN109894367A (en) * | 2017-12-11 | 2019-06-18 | 南京梅山冶金发展有限公司 | A kind of large blast furnace lump ore Screening Treatment method |
| CN114653594B (en) * | 2022-04-15 | 2023-05-30 | 广东亨益环保集团有限公司 | Post-type combined sorting process for sorting stock household garbage by using two-stage roller |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3181944A (en) * | 1962-05-07 | 1965-05-04 | Allied Chem | Zinc calcine for hydrometallurgical process |
| IT990357B (en) * | 1973-08-06 | 1975-06-20 | Centro Speriment Metallurg | PROCEDURE FOR THE PREPARATION OF THE SOLID FEEDING PHASE FOR FLUID BED REACTORS |
| AT400578B (en) * | 1994-03-24 | 1996-01-25 | Voest Alpine Ind Anlagen | METHOD FOR PROCESSING FINE ORE |
| DE19711629C2 (en) * | 1997-03-20 | 2000-01-13 | Ferrostaal Ag | Method and device for preparing fine ores for direct reduction |
-
1999
- 1999-07-27 AT AT0130099A patent/AT407346B/en not_active IP Right Cessation
-
2000
- 2000-06-16 CA CA 2378956 patent/CA2378956A1/en not_active Abandoned
- 2000-06-16 AU AU56826/00A patent/AU5682600A/en not_active Abandoned
- 2000-06-16 EP EP00942084A patent/EP1204773A1/en not_active Withdrawn
- 2000-06-16 JP JP2001512935A patent/JP2003505240A/en not_active Withdrawn
- 2000-06-16 KR KR1020027001091A patent/KR20020016918A/en not_active Application Discontinuation
- 2000-06-16 WO PCT/EP2000/005565 patent/WO2001007670A1/en not_active Application Discontinuation
- 2000-06-16 MX MXPA02000629A patent/MXPA02000629A/en not_active Application Discontinuation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3026129A4 (en) * | 2013-07-25 | 2017-03-08 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Method for manufacturing briquettes and reduced iron |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2003505240A (en) | 2003-02-12 |
| MXPA02000629A (en) | 2002-08-30 |
| AT407346B (en) | 2001-02-26 |
| AU5682600A (en) | 2001-02-13 |
| EP1204773A1 (en) | 2002-05-15 |
| ATA130099A (en) | 2000-07-15 |
| KR20020016918A (en) | 2002-03-06 |
| WO2001007670A1 (en) | 2001-02-01 |
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