CA2019959C - Method and apparatus for process for processing ground-up mixtures of minerals - Google Patents
Method and apparatus for process for processing ground-up mixtures of mineralsInfo
- Publication number
- CA2019959C CA2019959C CA002019959A CA2019959A CA2019959C CA 2019959 C CA2019959 C CA 2019959C CA 002019959 A CA002019959 A CA 002019959A CA 2019959 A CA2019959 A CA 2019959A CA 2019959 C CA2019959 C CA 2019959C
- Authority
- CA
- Canada
- Prior art keywords
- separator
- free fall
- discharge ducts
- underpressure
- generally horizontal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000000034 method Methods 0.000 title claims abstract description 30
- 239000000203 mixture Substances 0.000 title claims abstract description 22
- 229910052500 inorganic mineral Inorganic materials 0.000 title claims abstract description 13
- 239000011707 mineral Substances 0.000 title claims abstract description 13
- 159000000001 potassium salts Chemical class 0.000 claims abstract description 17
- 238000000926 separation method Methods 0.000 claims abstract description 7
- 239000002245 particle Substances 0.000 claims description 8
- 230000003750 conditioning effect Effects 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- 239000012811 non-conductive material Substances 0.000 claims 2
- 230000005686 electrostatic field Effects 0.000 claims 1
- 239000004020 conductor Substances 0.000 abstract description 4
- 230000001143 conditioned effect Effects 0.000 abstract description 3
- 239000003570 air Substances 0.000 description 15
- 239000012141 concentrate Substances 0.000 description 8
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 5
- 235000010755 mineral Nutrition 0.000 description 4
- 235000002639 sodium chloride Nutrition 0.000 description 3
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- YGSDEFSMJLZEOE-UHFFFAOYSA-N salicylic acid Chemical compound OC(=O)C1=CC=CC=C1O YGSDEFSMJLZEOE-UHFFFAOYSA-N 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052925 anhydrite Inorganic materials 0.000 description 1
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 1
- 229910052928 kieserite Inorganic materials 0.000 description 1
- FJKROLUGYXJWQN-UHFFFAOYSA-N papa-hydroxy-benzoic acid Natural products OC(=O)C1=CC=C(O)C=C1 FJKROLUGYXJWQN-UHFFFAOYSA-N 0.000 description 1
- 229960004889 salicylic acid Drugs 0.000 description 1
- 239000011833 salt mixture Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C7/00—Separating solids from solids by electrostatic effect
- B03C7/003—Pretreatment of the solids prior to electrostatic separation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C7/00—Separating solids from solids by electrostatic effect
- B03C7/006—Charging without electricity supply, e.g. by tribo-electricity, pyroelectricity
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C7/00—Separating solids from solids by electrostatic effect
- B03C7/02—Separators
- B03C7/12—Separators with material falling free
Abstract
A process and a device is disclosed for the electrostatic separation of mineral mixtures, especially raw potassium salts, in a free fall separator, into a coarse fraction and a fine fraction, after the ground-up mixture has been conditioned and electrostatically charged. Each of the fractions is separately electrostatically processed and the fine fraction is fed to a free fall separator where a vertical air flow is generated in the direction from the inlet to foot of the separator. To generate the air flow, tubes or annular pipes made of electrically non-conducting material, are arranged in the discharge ducts of the free fall separator. These devices have nozzle openings oriented towards the foot of the separator and they are connected to a device which generates a negative pressure.
Description
It is well known that mixtures of minerals, and in particular raw potassium salts, can be broken down into their component fractions by electrostatic means. To accomplish this, the raw potassium salts are ground until the intergrowths are destroyed, then the fraction having a grain size of up 5 to 2 mm is separated out of the ground material. This fraction of the raw potassium salts is then mixed with small amounts of chemical conditioners which facilitate the transfer of charge between the particles of the mixture during the subsequent step when the mixture is triboelectrically charged under defined conditions of relative humidity and temperature in the ambient air. The 10 triboelectrically charged mixture is then fed to electrostatic free fall separators where it is separated into a product fraction, middlings and residue. This method of processing potassium salts is described in detail by Singewald et al.
in the journal "Chem.-lng.-Techn." 55 (1983), pp. 30 to 45.
However, it is also a known fact that extremely fine fractions having 15 grain sizes of less than 0.1 mm, which may be present in substantial quantities in the ground mixtures of potassium salts, exert a highly disruptive influence on the electrostatic processing of these mixtures. Therefore, German Patents 12 59 803 and 12 79 572 reveal processes by means of which these disrupting influences can be largely avoided. According to these processes, 20 the ground-up mixture of raw potassium salts can be broken down in a first electrostatic stage into a "fines" fraction, comprising the extremely fine-sizedfractions, a residue, a pre-concentrated product fraction and possibly a middlings fraction. In both cases, it si necessary by means of a wet process to further treat the separated fines fraction before a saleable product can be 25 produced from it. The considerably amounts (up to 20%) of fine-sized materialpresent in ground-up raw potassium salts can cause serious disruptions when the material is then further processes by wet means.
This gave rise to the need to find ways by which even the fine-sized fractions of ground mixtures of minerals, and in particular raw potassium salts,30 can be processed electrostatically, i.e. using dry methods.
In general terms, the present invention provides, in one aspect thereof, a process for processing ground-up mixtures of minerals, especially raw potassium slats, having substantial amounts of fines, by means of electrostatic separation in free fall separators following conditioning and triboelectric r D
_ ~3~ 2019~59 charging wherein, following conditioning and triboelectric charging, the mineralmixture is separated in a defined separation size range into a coarse fraction and a fine fraction, and the coarse fraction is then electrostatically processedin free fall separators, while the fine fraction is separately fed to an electrostatic free fall separator in which the fine fraction is exposed to an electric filed on which is superimposed an air flow oriented vertically from theinlet to the foot of the separator.
In another aspect, the invention provides apparatus for carrying out the above method, wherein tubes or annular pipes made of electrically non-conducting materials are arranged in the discharge ducts of the free fall separator, said pipes or tubes being provided with a number of nozzle openings directed towards the foot of the separator and being connected with a device which produces a negative pressure.
The separation size range in question here is between 0.04 and 0.315 mm. The preferred size range for this process is between 0.063 and 0.2 mm.
The flow rate of the vertical air flow is advantageously less than 3 m/sec and preferentially less than 1 m/sec.
The invention is described below on the basis of the processing of raw potassium salt. In order to implement the process according to the invention, the raw potassium slat is ground to sizes below 2 mm and conditioned using known chemical conditions; it is then triboelectrically charged by setting the individual salt particles in vigorous motion, for example in a fluidized bed, in a suitably warmed carrier air flow having a predetermined relative humidity. The fine fractions of the salt mixture are carried out of the fluidized bed in the carrier air flow and then separated from the carrier air, for example in a cyclone or another suitable fines separating device.
The separated fine fraction containing particle sizes of less than 0.1 mm is then fed into an electrostatic tube, belt or roll separator, preferably a tube or belt separator.
Particularly good separating results can be achieved in separators n which an air flow is generated and maintained from the feed chute to the bottom end of the separator. The flow rate of this air flow should be less than 3 m/sec, and preferentially less than 1 m/sec.
D
~ -4 2019gS9 The air flow in the direction of fall through the free fall shaft is almost totally free of swirling and this considerably improves the deflection of the charged salt particles, particularly the finest low-weight sizes, towards the oppositely charged electrode.
An air flow of this type can advantageously be generated by means of tubes made of electrically non-conducting material whose walls contain a large number of nozzle-like openings pointing towards the foot of the separator and connected via a control device to a system for generating negative pressure.
These tubes are arranged in the particles discharge ducts of the separator; theyrun parallel to its horizontal axis or lower edge and they extend over almost the entire length of the separating ducts.
The present invention will be described by way of examples, with reference to the accompanying drawings, wherein:
Figure 1 is a diagrammatic representation of an apparatus according to 1 5 the present invention;
Figure 2 is a diagrammatic representation of the separator of Figure 1, showing a detail thereof;
Figure 3 is a diagrammatic representation of a method according to German Patent 12 59 803; and Figure 4 is a diagrammatic representation similar to that of Figure 3 but showing the method of the present invention.
Turning now to Figures 1 and 2, a device is depicted by way of example in diagrammatic form in Figures 1 and 2.
The apparatus is shown as comprising an upright rectangular chamber or free fall shaft 2. The free fall shaft 2 displays two side walls which are generally upright and each of which merges with a downwardly and inwards inclined bottom wall, so that the bottom walls form a hopper-like downwardly narrowing generally wedge shaped configuration which extends parallel with obtuse angled corners between the side walls and the bottom walls.
Below the free fall shaft 2, which is bounded by the belt electrodes 1, one at each side wall of the chamber 2, generally horizontal tubes 7 are arranged each in one of particle discharge ducts 4 to 6. As shown, the tubes 7 only partly obstruct the passage through the respective discharge duct 4 -~5~ 2019959 6. The tubes 7 are connected to the device for generating negative pressure, for instance a vacuum pump.
Fig. 2 depicts, in diagrammatic form, a part section through such a tube 7, showing the openings 8 oriented towards the bottom of the discharge duct.
5 It is, of course, possible to provide a large number of such tubes 7 in a free fall shaft.
It is also, however, possible to fit in the discharge ducts of the separator on or more horizontally arranged annular pipes (not shown in the diagrammatic drawings) made of electrically non-conducting material which would define 10 horizontally elongated annular chamber having in their outer walls downwardlyoriented nozzles or nozzle openings. With these annular pipes it is also possible to achieve the desired air flow if the annular chambers are connected via suitable control devices to a device for generating negative pressure.
The air flowing through the nozzle-like openings 8 into the tubes 7 or the 15 annular chamber creates a slight negative pressure in the upper part 9 of theparticle discharge ducts, and in turn this negative pressure creates, in the free fall shaft 2, a vertically directed downward air flow running from the inlet to the bottom of the separator.
As already mentioned, when they are separated from the coarse 20 fractions and further processed by wet means, the fines fraction (up to 20%) contained in the ground-up raw potassium salts can considerably disrupt the dissolving process and drastically increase the amounts of process liquor used.
These disadvantage are avoided by the process according tot he invention and are replaced by the advantages of being able to fully process the raw 25 potassium salts by the dry electrostatic separating procedure.
In the following examples, a ground-up raw potassium salt is used as the mineral mixture.
This raw potassium salt has a K20 content of 18.2%. Apart from very small amounts of kieserite and anhydrite, the remainder consists of rock salt.
30 The raw potassium salt is conditioned using 150 g/t salicylic acid and then fed to the fluidized bed device where it is treated and triboelectrically charged byair having 10% relative humidity and a temperature of 60C.
The coarse and fine fractions separated in the fluidized bed device have the following screen analyses:
D
i -6- ` 2019959 Coarse Fraction Fines Fraction Grain Size (mm) Content wt.% Grain Size (mm) Content wt.%
>0.5 29.2 >0.1 11.1 0.2 to 0.5 47.5 0.063 to 0.1 33.3 0.16 to 0.2 8.7 0.04 to 0.063 31.7 0.1 to 0.16 12.1 >0.04 23.9 >0.1 2.5 In each case 10 t of the raw potassium salt pretreated in the manner described are used in the following examples.
10 ExamPle 1 (comparison, as per German Patent 12 59 803) This example follows the process flow chart illustrated in Fig.3. The following separating results are obtained:
Amount K20 Content K20 Yield (t) (%) (%) Product pre-concentrate 2.98 44.1 72.2 Fines fraction 0.76 38.7 16.1 Residue 6.26 3.4 11.7 Mixing the product pre-concentratethe fines fraction gives a concentrate having 43.0 wt.% K20 in a yield of 88.3 wt.% K20. The residue contains a mean K20 content of 3.4 wt%, namely 2.3 wt.% in the >0.1 mm screen fraction and 8.2 wt.% in the <0.1 mm screen fraction.
20 Example 2 (comparison, as per diagram in Figure 4, but without air flow) Following the triboelectric charging process, the fine and coarse fractions are fed to separate electrostatic free fall separators. The following separating results are obtained:
D
Quantity Content K2O Yield Relative to Relative to Separator Overall Process (t) (%) (%) (%) Coarse Concentrate 2.88 46.7 92.7 73.9 Coarse Residue 5.32 2.0 7.3 5.9 Fine Concentrate0.83 35.5 80.2 16.2 Fine Residue 0.97 7.5 19.8 4.0 Mixing the coarse and fine concentrates gives a concentrate having a 44.2 wt.% K2O content in a yield of 90.1 wt.% K2O. This corresponds to an increase of 1.8% in the K2O yield compared with the results obtained in Example 1.
10 ExamPle 3 (according to the invention, separate processing of the fines fraction by means of an air flow in the free fall shaft, as per the diagram in Fig. 4) The following separating results are obtained:
QuantityContentK2O Yield Relative to Relative to Separator Overall Process (t) (%) (%) (%) Coarse Concentrate 2.88 46.7 92.7 74.0 Coarse Residue 5.32 2.0 7.3 5.9 Fine Concentrate0.86 39.6 92.8 18.7 Fine Residue 0.94 2.8 7.2 1.4 'l D
-8- 201~S9 Mixing the coarse and fine concentrates give a concentrate having a 45.1 wt.% K20 content in a yield of 92.7 wt.% K20. Compared with the results according to Examples 1 and 2, this is where the highest values are obtained. A comparison of the separating results further shows that the fines 5 separating efficiency of the separator is considerably improved by the vertical air flow.
D
in the journal "Chem.-lng.-Techn." 55 (1983), pp. 30 to 45.
However, it is also a known fact that extremely fine fractions having 15 grain sizes of less than 0.1 mm, which may be present in substantial quantities in the ground mixtures of potassium salts, exert a highly disruptive influence on the electrostatic processing of these mixtures. Therefore, German Patents 12 59 803 and 12 79 572 reveal processes by means of which these disrupting influences can be largely avoided. According to these processes, 20 the ground-up mixture of raw potassium salts can be broken down in a first electrostatic stage into a "fines" fraction, comprising the extremely fine-sizedfractions, a residue, a pre-concentrated product fraction and possibly a middlings fraction. In both cases, it si necessary by means of a wet process to further treat the separated fines fraction before a saleable product can be 25 produced from it. The considerably amounts (up to 20%) of fine-sized materialpresent in ground-up raw potassium salts can cause serious disruptions when the material is then further processes by wet means.
This gave rise to the need to find ways by which even the fine-sized fractions of ground mixtures of minerals, and in particular raw potassium salts,30 can be processed electrostatically, i.e. using dry methods.
In general terms, the present invention provides, in one aspect thereof, a process for processing ground-up mixtures of minerals, especially raw potassium slats, having substantial amounts of fines, by means of electrostatic separation in free fall separators following conditioning and triboelectric r D
_ ~3~ 2019~59 charging wherein, following conditioning and triboelectric charging, the mineralmixture is separated in a defined separation size range into a coarse fraction and a fine fraction, and the coarse fraction is then electrostatically processedin free fall separators, while the fine fraction is separately fed to an electrostatic free fall separator in which the fine fraction is exposed to an electric filed on which is superimposed an air flow oriented vertically from theinlet to the foot of the separator.
In another aspect, the invention provides apparatus for carrying out the above method, wherein tubes or annular pipes made of electrically non-conducting materials are arranged in the discharge ducts of the free fall separator, said pipes or tubes being provided with a number of nozzle openings directed towards the foot of the separator and being connected with a device which produces a negative pressure.
The separation size range in question here is between 0.04 and 0.315 mm. The preferred size range for this process is between 0.063 and 0.2 mm.
The flow rate of the vertical air flow is advantageously less than 3 m/sec and preferentially less than 1 m/sec.
The invention is described below on the basis of the processing of raw potassium salt. In order to implement the process according to the invention, the raw potassium slat is ground to sizes below 2 mm and conditioned using known chemical conditions; it is then triboelectrically charged by setting the individual salt particles in vigorous motion, for example in a fluidized bed, in a suitably warmed carrier air flow having a predetermined relative humidity. The fine fractions of the salt mixture are carried out of the fluidized bed in the carrier air flow and then separated from the carrier air, for example in a cyclone or another suitable fines separating device.
The separated fine fraction containing particle sizes of less than 0.1 mm is then fed into an electrostatic tube, belt or roll separator, preferably a tube or belt separator.
Particularly good separating results can be achieved in separators n which an air flow is generated and maintained from the feed chute to the bottom end of the separator. The flow rate of this air flow should be less than 3 m/sec, and preferentially less than 1 m/sec.
D
~ -4 2019gS9 The air flow in the direction of fall through the free fall shaft is almost totally free of swirling and this considerably improves the deflection of the charged salt particles, particularly the finest low-weight sizes, towards the oppositely charged electrode.
An air flow of this type can advantageously be generated by means of tubes made of electrically non-conducting material whose walls contain a large number of nozzle-like openings pointing towards the foot of the separator and connected via a control device to a system for generating negative pressure.
These tubes are arranged in the particles discharge ducts of the separator; theyrun parallel to its horizontal axis or lower edge and they extend over almost the entire length of the separating ducts.
The present invention will be described by way of examples, with reference to the accompanying drawings, wherein:
Figure 1 is a diagrammatic representation of an apparatus according to 1 5 the present invention;
Figure 2 is a diagrammatic representation of the separator of Figure 1, showing a detail thereof;
Figure 3 is a diagrammatic representation of a method according to German Patent 12 59 803; and Figure 4 is a diagrammatic representation similar to that of Figure 3 but showing the method of the present invention.
Turning now to Figures 1 and 2, a device is depicted by way of example in diagrammatic form in Figures 1 and 2.
The apparatus is shown as comprising an upright rectangular chamber or free fall shaft 2. The free fall shaft 2 displays two side walls which are generally upright and each of which merges with a downwardly and inwards inclined bottom wall, so that the bottom walls form a hopper-like downwardly narrowing generally wedge shaped configuration which extends parallel with obtuse angled corners between the side walls and the bottom walls.
Below the free fall shaft 2, which is bounded by the belt electrodes 1, one at each side wall of the chamber 2, generally horizontal tubes 7 are arranged each in one of particle discharge ducts 4 to 6. As shown, the tubes 7 only partly obstruct the passage through the respective discharge duct 4 -~5~ 2019959 6. The tubes 7 are connected to the device for generating negative pressure, for instance a vacuum pump.
Fig. 2 depicts, in diagrammatic form, a part section through such a tube 7, showing the openings 8 oriented towards the bottom of the discharge duct.
5 It is, of course, possible to provide a large number of such tubes 7 in a free fall shaft.
It is also, however, possible to fit in the discharge ducts of the separator on or more horizontally arranged annular pipes (not shown in the diagrammatic drawings) made of electrically non-conducting material which would define 10 horizontally elongated annular chamber having in their outer walls downwardlyoriented nozzles or nozzle openings. With these annular pipes it is also possible to achieve the desired air flow if the annular chambers are connected via suitable control devices to a device for generating negative pressure.
The air flowing through the nozzle-like openings 8 into the tubes 7 or the 15 annular chamber creates a slight negative pressure in the upper part 9 of theparticle discharge ducts, and in turn this negative pressure creates, in the free fall shaft 2, a vertically directed downward air flow running from the inlet to the bottom of the separator.
As already mentioned, when they are separated from the coarse 20 fractions and further processed by wet means, the fines fraction (up to 20%) contained in the ground-up raw potassium salts can considerably disrupt the dissolving process and drastically increase the amounts of process liquor used.
These disadvantage are avoided by the process according tot he invention and are replaced by the advantages of being able to fully process the raw 25 potassium salts by the dry electrostatic separating procedure.
In the following examples, a ground-up raw potassium salt is used as the mineral mixture.
This raw potassium salt has a K20 content of 18.2%. Apart from very small amounts of kieserite and anhydrite, the remainder consists of rock salt.
30 The raw potassium salt is conditioned using 150 g/t salicylic acid and then fed to the fluidized bed device where it is treated and triboelectrically charged byair having 10% relative humidity and a temperature of 60C.
The coarse and fine fractions separated in the fluidized bed device have the following screen analyses:
D
i -6- ` 2019959 Coarse Fraction Fines Fraction Grain Size (mm) Content wt.% Grain Size (mm) Content wt.%
>0.5 29.2 >0.1 11.1 0.2 to 0.5 47.5 0.063 to 0.1 33.3 0.16 to 0.2 8.7 0.04 to 0.063 31.7 0.1 to 0.16 12.1 >0.04 23.9 >0.1 2.5 In each case 10 t of the raw potassium salt pretreated in the manner described are used in the following examples.
10 ExamPle 1 (comparison, as per German Patent 12 59 803) This example follows the process flow chart illustrated in Fig.3. The following separating results are obtained:
Amount K20 Content K20 Yield (t) (%) (%) Product pre-concentrate 2.98 44.1 72.2 Fines fraction 0.76 38.7 16.1 Residue 6.26 3.4 11.7 Mixing the product pre-concentratethe fines fraction gives a concentrate having 43.0 wt.% K20 in a yield of 88.3 wt.% K20. The residue contains a mean K20 content of 3.4 wt%, namely 2.3 wt.% in the >0.1 mm screen fraction and 8.2 wt.% in the <0.1 mm screen fraction.
20 Example 2 (comparison, as per diagram in Figure 4, but without air flow) Following the triboelectric charging process, the fine and coarse fractions are fed to separate electrostatic free fall separators. The following separating results are obtained:
D
Quantity Content K2O Yield Relative to Relative to Separator Overall Process (t) (%) (%) (%) Coarse Concentrate 2.88 46.7 92.7 73.9 Coarse Residue 5.32 2.0 7.3 5.9 Fine Concentrate0.83 35.5 80.2 16.2 Fine Residue 0.97 7.5 19.8 4.0 Mixing the coarse and fine concentrates gives a concentrate having a 44.2 wt.% K2O content in a yield of 90.1 wt.% K2O. This corresponds to an increase of 1.8% in the K2O yield compared with the results obtained in Example 1.
10 ExamPle 3 (according to the invention, separate processing of the fines fraction by means of an air flow in the free fall shaft, as per the diagram in Fig. 4) The following separating results are obtained:
QuantityContentK2O Yield Relative to Relative to Separator Overall Process (t) (%) (%) (%) Coarse Concentrate 2.88 46.7 92.7 74.0 Coarse Residue 5.32 2.0 7.3 5.9 Fine Concentrate0.86 39.6 92.8 18.7 Fine Residue 0.94 2.8 7.2 1.4 'l D
-8- 201~S9 Mixing the coarse and fine concentrates give a concentrate having a 45.1 wt.% K20 content in a yield of 92.7 wt.% K20. Compared with the results according to Examples 1 and 2, this is where the highest values are obtained. A comparison of the separating results further shows that the fines 5 separating efficiency of the separator is considerably improved by the vertical air flow.
D
Claims (11)
1 . Method for processing ground-up mixtures of minerals, particularly potassium salts having substantial amounts of fines, said method comprising the steps of:
chemical conditioning of the mineral mixture;
subsequently triboelectrically charging the mixture;
subsequently separating the mixture into a coarse fraction and a fine fraction, each fraction having a defined size range;
electrostatically separating the coarse fraction in a free fall separator;
electrostatically separating the fine fraction in a free fall separator in an electrostatic field on which is superimposed an air flow oriented vertically from the inlet to the foot of the separator.
chemical conditioning of the mineral mixture;
subsequently triboelectrically charging the mixture;
subsequently separating the mixture into a coarse fraction and a fine fraction, each fraction having a defined size range;
electrostatically separating the coarse fraction in a free fall separator;
electrostatically separating the fine fraction in a free fall separator in an electrostatic field on which is superimposed an air flow oriented vertically from the inlet to the foot of the separator.
2. The method of claim 1, wherein the separation in the coarse fraction and a fine fraction is carried out in a separation particle size range of from 0.04 to 0.315 mm.
3. The method of claim 2, wherein the separation in a coarse fraction and a fine fraction is carried out in a predetermined particle size range of 0.063 to 0.2 mm.
4. The method of claim 1, wherein the flow rate of the vertical air flow is less than 3 m/sec.
5. The method of claim 4, wherein the flow rate is less than 1 m/sec.
6. Electrostatic free fall separator for processing ground-up mixtures of minerals, especially raw potassium salts, having substantial amounts of fines, said separator comprising, in combination:
(a) a generally vertical free fall shaft having an upper feeding end and a lower end which communicates with a plurality of discharge ducts;
(b) said discharge ducts being provided with tubular members;
(c) each said tubular member being connected to a source of underpressure;
(d) said tubular members defining a plurality of nozzle openings directed in a downward direction.
(a) a generally vertical free fall shaft having an upper feeding end and a lower end which communicates with a plurality of discharge ducts;
(b) said discharge ducts being provided with tubular members;
(c) each said tubular member being connected to a source of underpressure;
(d) said tubular members defining a plurality of nozzle openings directed in a downward direction.
7. Electrostatic free fall separator for processing ground-up mixtures of minerals, especially raw potassium salts, having substantial amounts of fines, said separator comprising, in combination:
(a) a generally vertical free fall shaft having an upper feeding end and a lower end which communicates with a plurality of discharge ducts;
(b) said discharge ducts being provided with generally horizontal tubes disposed in each of said discharge ducts;
(c) said generally horizontal tubes being connected to a source of underpressure;
(d) each said generally horizontal tube being provided with a plurality of downwardly directed nozzle openings.
(a) a generally vertical free fall shaft having an upper feeding end and a lower end which communicates with a plurality of discharge ducts;
(b) said discharge ducts being provided with generally horizontal tubes disposed in each of said discharge ducts;
(c) said generally horizontal tubes being connected to a source of underpressure;
(d) each said generally horizontal tube being provided with a plurality of downwardly directed nozzle openings.
8. Electrostatic free fall separator for processing ground-up mixtures of minerals, especially raw potassium salts, having substantial amounts of fines, said separator comprising, in combination:
(a) a generally vertical free fall shaft having an upper feeding end and a lower end which communicates with a plurality of discharge ducts;
(b) said discharge ducts being passages which are provided with generally horizontal tubes made of an electrically non-conductive material and disposed in each of said discharge ducts such that they only partly obstruct the respective duct;
(c) said generally horizontal tubes being connected to a source of underpressure;
(d) each said generally horizontal tube being provided with a plurality of downwardly directed nozzle openings;
whereby the tubes transmit each to the respective passage an underpressure when the source of underpressure is activated.
(a) a generally vertical free fall shaft having an upper feeding end and a lower end which communicates with a plurality of discharge ducts;
(b) said discharge ducts being passages which are provided with generally horizontal tubes made of an electrically non-conductive material and disposed in each of said discharge ducts such that they only partly obstruct the respective duct;
(c) said generally horizontal tubes being connected to a source of underpressure;
(d) each said generally horizontal tube being provided with a plurality of downwardly directed nozzle openings;
whereby the tubes transmit each to the respective passage an underpressure when the source of underpressure is activated.
9. Electrostatic free fall separator for processing ground-up mixtures of minerals, especially raw potassium salts, having substantial amounts of fines, said separator comprising, in combination:
(a) a generally vertical free fall shaft having an upper feeding end and a lower end which communicates with a plurality of discharge ducts;
(b) said discharge ducts being provided with generally horizontal tubes disposed in each of said discharge ducts;
(c) said generally horizontal tubes defining a generally horizontal annular chamber connected to a source of underpressure;
(d) each said annular chamber communicating with the respective discharge duct via a plurality of downwardly directed nozzle openings;
whereby the tubes transmit each to the respective passage an underpressure when the source of underpressure is activated.
(a) a generally vertical free fall shaft having an upper feeding end and a lower end which communicates with a plurality of discharge ducts;
(b) said discharge ducts being provided with generally horizontal tubes disposed in each of said discharge ducts;
(c) said generally horizontal tubes defining a generally horizontal annular chamber connected to a source of underpressure;
(d) each said annular chamber communicating with the respective discharge duct via a plurality of downwardly directed nozzle openings;
whereby the tubes transmit each to the respective passage an underpressure when the source of underpressure is activated.
10. Electrostatic free fall separator for processing ground-up mixtures of minerals, especially raw potassium salts, having substantial amounts of fines, said separator comprising, in combination:
(a) a generally vertical free fall shaft having an upper feeding end and a lower end which communicates with a plurality of discharge ducts;
(b) said discharge ducts being passages which are provided with generally horizontal tubes of annular cross-section made of an electrically non-conductive material and disposed in each of said discharge ducts such that they only partly obstruct the respective duct;
(c) said generally horizontal tubes being connected to a source of underpressure;
(d) each said generally horizontal tube being provided with a plurality of downwardly directed nozzle openings;
whereby the tubes transmit each to the respective passage an underpressure when the source of underpressure is activated.
(a) a generally vertical free fall shaft having an upper feeding end and a lower end which communicates with a plurality of discharge ducts;
(b) said discharge ducts being passages which are provided with generally horizontal tubes of annular cross-section made of an electrically non-conductive material and disposed in each of said discharge ducts such that they only partly obstruct the respective duct;
(c) said generally horizontal tubes being connected to a source of underpressure;
(d) each said generally horizontal tube being provided with a plurality of downwardly directed nozzle openings;
whereby the tubes transmit each to the respective passage an underpressure when the source of underpressure is activated.
11. A device according to one of claims 7, 8, 9 or 10 wherein:
(a) said free fall shaft has the general shape of an upright rectangular chamber including two opposed side walls and two downwardly convergent, opposed bottom walls defining a straight, elongated lower wedge-shaped portion at which the chamber merges with said discharge ducts;
(b) said horizontal tubes being generally parallel with the elongation of the wedge-shaped portion.
(a) said free fall shaft has the general shape of an upright rectangular chamber including two opposed side walls and two downwardly convergent, opposed bottom walls defining a straight, elongated lower wedge-shaped portion at which the chamber merges with said discharge ducts;
(b) said horizontal tubes being generally parallel with the elongation of the wedge-shaped portion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3921072.3 | 1989-06-28 | ||
| DE3921072A DE3921072A1 (en) | 1989-06-28 | 1989-06-28 | Electrostatic processing of crude potash with no wet stage - using free fall separator in which vertical air flow is maintained |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2019959A1 CA2019959A1 (en) | 1990-12-28 |
| CA2019959C true CA2019959C (en) | 1996-09-10 |
Family
ID=6383706
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002019959A Expired - Lifetime CA2019959C (en) | 1989-06-28 | 1990-06-27 | Method and apparatus for process for processing ground-up mixtures of minerals |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA2019959C (en) |
| DD (1) | DD300081A5 (en) |
| DE (1) | DE3921072A1 (en) |
| IT (1) | IT1247699B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103977903B (en) * | 2013-02-07 | 2017-03-29 | 李庆宪 | Electrostatic conduction-type preparation equipment |
| CN104941812B (en) * | 2015-07-20 | 2017-03-29 | 中国矿业大学 | The fine granule material friction electrical selection method and device of lateral negative-pressure adsorption |
| CN105903570B (en) * | 2016-05-20 | 2017-08-29 | 昆明理工大学 | A kind of impact type triboelectric separator |
-
1989
- 1989-06-28 DE DE3921072A patent/DE3921072A1/en active Granted
-
1990
- 1990-06-27 IT IT04809790A patent/IT1247699B/en active IP Right Grant
- 1990-06-27 CA CA002019959A patent/CA2019959C/en not_active Expired - Lifetime
- 1990-06-27 DD DD342160A patent/DD300081A5/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| IT1247699B (en) | 1994-12-30 |
| DE3921072A1 (en) | 1991-01-10 |
| IT9048097A0 (en) | 1990-06-27 |
| IT9048097A1 (en) | 1991-12-27 |
| DE3921072C2 (en) | 1991-08-08 |
| DD300081A5 (en) | 1992-05-21 |
| CA2019959A1 (en) | 1990-12-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3493109A (en) | Process and apparatus for electrostatically separating ores with charging of the particles by triboelectricity | |
| US4266673A (en) | Apparatus for classifying dust materials | |
| CA2221386C (en) | Electrostatic separation device for sorting triboelectrically charged mixtures | |
| US3975263A (en) | Material separation apparatus and method | |
| US4950388A (en) | Separation of mixtures in a wind tunnel | |
| SU938733A3 (en) | Pneumatic classifier | |
| EP0420380A2 (en) | Particle separator | |
| US5580002A (en) | Method and apparatus for heating and grinding materials | |
| US4715951A (en) | Apparatus for separating granulate material | |
| EP0456913A1 (en) | Suction-sifter | |
| US4133749A (en) | Process of separating solid granular metallurgical products and their precursors and apparatus | |
| US5080235A (en) | Small particle separator | |
| CA2019959C (en) | Method and apparatus for process for processing ground-up mixtures of minerals | |
| US4070274A (en) | Coarse concentrated iron ore for catalytic purposes | |
| US6359246B1 (en) | Process and device for separating broken beans and shells | |
| JP2000262929A (en) | Method for sorting crushed material and apparatus therefor | |
| US5160351A (en) | Process of and apparatus for cleaning a dedusting electrostatic precipitator | |
| WO2011041828A1 (en) | Pneumatic separation of loose materials | |
| AU592010B2 (en) | Separation of mixtures in a wind tunnel | |
| SU1176976A1 (en) | Pneumatic separator for loose materials | |
| CA2019960C (en) | Process for treating mineral mixtures | |
| WO1998036840A1 (en) | Equipment and method for producing ultra fine dry powders by means of a high-energy power gas | |
| US11260402B2 (en) | Electrostatic separation device, and associated separation method and use | |
| US20240009707A1 (en) | Air classifier | |
| EP4037845B1 (en) | Device for sorting powder particles |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |