CA2397796C - Method and apparatus for grinding of particulate material - Google Patents
Method and apparatus for grinding of particulate material Download PDFInfo
- Publication number
- CA2397796C CA2397796C CA002397796A CA2397796A CA2397796C CA 2397796 C CA2397796 C CA 2397796C CA 002397796 A CA002397796 A CA 002397796A CA 2397796 A CA2397796 A CA 2397796A CA 2397796 C CA2397796 C CA 2397796C
- Authority
- CA
- Canada
- Prior art keywords
- shaft
- cross
- downwardly
- feed shaft
- grinding
- 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 - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C4/00—Crushing or disintegrating by roller mills
- B02C4/28—Details
- B02C4/286—Feeding devices
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- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Crushing And Grinding (AREA)
- Disintegrating Or Milling (AREA)
- Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
- Control And Other Processes For Unpacking Of Materials (AREA)
Abstract
A description is provided of a method as well as an apparatus for grinding particulate material, such as cement raw materials, cement clinker or similar materials, in a roller mill (1) by subjecting the material to pressing action in a zone (13) between opposite, rotating surfaces where the material is directed to the grinding zone via a feed shaft (11). The method is peculiar in that the material in the feed shaft (11) is accelerated through the action of gravity to a desired velocity without involving essential air admixture, whereas the apparatus is peculiar in that the feed shaft is essentially of a vertical configuration, with a downwardly reduced cross-section, where the reduction of the shafts cross-sectional circumference per height unit is downwardly decreasing.The described configuration of the feed shaft has, surprisingly, proved that the material over a given height of fall may attain high velocities and that this is achievable without involving admixture of air into the material. It has thus been established that it will be possible for the material to attain velocities which are close to the velocity achievable in connection with the free fall of individual particles. <IMG>
Description
METHOD AND APPARATUS FOR GRINDING OF PARTICULATE MATERIAL
The present invention relates to an apparatus for grinding of particulate material such as cement raw materiafs, cement clinker or similar materials, in a roller mill, such as a roller press, ring-roller mill, vertical mill or a similar unit. The shaft being of substantially vertical configuration and with a downwardly reduced cross-section.
An apparatus of the aforementioned kind is prior art.
In recent years, developments in grinding technology have primarily been devoted to impriving the cost efficiency of the grinding process. In this context, the primary focus has been to improve the operating economy of the grinding process and to reduce the capital cost of the grinding machines relative to their capacity ratings. A method widely used to lower the investments costs involves uprating of the operating speed of a machine, and hence its productivity. Needless to say, the operating speed of a machine can only be increased up to a certain point, and, furthermore, it is a recongnized fact that problems are likely to occur in connection with the operation of, for example, a roller press if the peripheral velocity of the rollers is increased arbitrarily.
Such operating problems may be ascribable to many different causes. On explanation could be the difficulty of achieving an acceleration of the material shich is to be ground in the roller press to an extent which corresponds to the peripheral velocity of the rollers. Such acceleration of the material is usually achieved by means of the rollers by physical contact with the latter and/or through the action of gravity. However, the capability of the rollers is restricted to a very short range of operation, thereby F ~ 8~h 'at ''~ PCT/IB01/00057 PCT intsmat:,:?r :,)itcatipn severly limiting the rate of acceleration, and in a shaft the force of gravity will either be counteracted by the friction of the material against the shaft and/or the friction present in the material itself. Also, acceleration accomplished in a traditional shaft will also entail significant admixture of air, which is undesirable, and this will also adversely affect the grinding process. Use of a vertical shaft with a circular or rectangular cross-section and with an identical cross-sectional area across the entire length will enable the force of gravity to accelerate the material to a high velocity, but in this scenario there will be a simultaneous increase in the distance between the particles, thereby decreasing the density of the material an involving air admixture. By using a shaft of a pyrimidal or conical configuration, it will be possible to maintain the distance between the particles, but in a shaft of this type the material will be influenced by forces of friction which are so substantial that the terminal velocities attainable are quite small. In such ordinary shafts the cross-sectional circumference is a liniarly decreasing function of the height. The reduction of the cross-sectional circumference per height unit thus remains constant for these shafts.
It is the objective of the present, invention to provide an apparatus for remedying the aforementioned deficiencies.
This is achieved by an apparatus of the kind mentioned in the introduction, and being characterized in that the reduction of the shaft's cross-sectional circumference per heiht unit is downwardly decreasing.
The described configuration of the feed shaft has, -surprisingly, proved that the material over a given height AMENDED SHEET
of fall may attain high velocities, and that this is feasible without involving admixture of air into the material. It has thus been established that it will be possible for the material- to attain velocities which are close to t he velocity achievable in connection with the free fall of individual particles.
The material can be accelerated to a velocity of more than 1.5 m/s. However, it is preferred that the material be accelerated to a velocity of more than 5 m/s, and preferably of more t:an 10 m/s.
An example of the cross-sectional characteristics according to the invention is known from the form of a free-falling water jet, for example from a slow-running water tap. At the top, at the outlet of the water tap, the water flow rate is quite small, with the width of the water jet corresponding roughly to the outlet. Further downstream of the jet the force of gravity has increased the water flow rate, but since the water flow throughout the jet is the same, and since the density throughout the jet is also the same, this means that the cross-section of the water jet is smaller. In this way the water jet will attain an almost hyperbolic shape and the characteristics of the cross-sectional area as a functior_ of the height of fall can be expressed by means of the formula:
V
(1) A=~1+0) _gh , where A is the cross-sectional area V is the volume flow g is the gravity acceleration h is the ~eight of fall A is a correction element which describes the friction in the mater=al, assuming for water a small value which is close to C
The water jet must be assumed to roughly circular and, therefore, its circumference can be calculated on the basis of the formula:
The present invention relates to an apparatus for grinding of particulate material such as cement raw materiafs, cement clinker or similar materials, in a roller mill, such as a roller press, ring-roller mill, vertical mill or a similar unit. The shaft being of substantially vertical configuration and with a downwardly reduced cross-section.
An apparatus of the aforementioned kind is prior art.
In recent years, developments in grinding technology have primarily been devoted to impriving the cost efficiency of the grinding process. In this context, the primary focus has been to improve the operating economy of the grinding process and to reduce the capital cost of the grinding machines relative to their capacity ratings. A method widely used to lower the investments costs involves uprating of the operating speed of a machine, and hence its productivity. Needless to say, the operating speed of a machine can only be increased up to a certain point, and, furthermore, it is a recongnized fact that problems are likely to occur in connection with the operation of, for example, a roller press if the peripheral velocity of the rollers is increased arbitrarily.
Such operating problems may be ascribable to many different causes. On explanation could be the difficulty of achieving an acceleration of the material shich is to be ground in the roller press to an extent which corresponds to the peripheral velocity of the rollers. Such acceleration of the material is usually achieved by means of the rollers by physical contact with the latter and/or through the action of gravity. However, the capability of the rollers is restricted to a very short range of operation, thereby F ~ 8~h 'at ''~ PCT/IB01/00057 PCT intsmat:,:?r :,)itcatipn severly limiting the rate of acceleration, and in a shaft the force of gravity will either be counteracted by the friction of the material against the shaft and/or the friction present in the material itself. Also, acceleration accomplished in a traditional shaft will also entail significant admixture of air, which is undesirable, and this will also adversely affect the grinding process. Use of a vertical shaft with a circular or rectangular cross-section and with an identical cross-sectional area across the entire length will enable the force of gravity to accelerate the material to a high velocity, but in this scenario there will be a simultaneous increase in the distance between the particles, thereby decreasing the density of the material an involving air admixture. By using a shaft of a pyrimidal or conical configuration, it will be possible to maintain the distance between the particles, but in a shaft of this type the material will be influenced by forces of friction which are so substantial that the terminal velocities attainable are quite small. In such ordinary shafts the cross-sectional circumference is a liniarly decreasing function of the height. The reduction of the cross-sectional circumference per height unit thus remains constant for these shafts.
It is the objective of the present, invention to provide an apparatus for remedying the aforementioned deficiencies.
This is achieved by an apparatus of the kind mentioned in the introduction, and being characterized in that the reduction of the shaft's cross-sectional circumference per heiht unit is downwardly decreasing.
The described configuration of the feed shaft has, -surprisingly, proved that the material over a given height AMENDED SHEET
of fall may attain high velocities, and that this is feasible without involving admixture of air into the material. It has thus been established that it will be possible for the material- to attain velocities which are close to t he velocity achievable in connection with the free fall of individual particles.
The material can be accelerated to a velocity of more than 1.5 m/s. However, it is preferred that the material be accelerated to a velocity of more than 5 m/s, and preferably of more t:an 10 m/s.
An example of the cross-sectional characteristics according to the invention is known from the form of a free-falling water jet, for example from a slow-running water tap. At the top, at the outlet of the water tap, the water flow rate is quite small, with the width of the water jet corresponding roughly to the outlet. Further downstream of the jet the force of gravity has increased the water flow rate, but since the water flow throughout the jet is the same, and since the density throughout the jet is also the same, this means that the cross-section of the water jet is smaller. In this way the water jet will attain an almost hyperbolic shape and the characteristics of the cross-sectional area as a functior_ of the height of fall can be expressed by means of the formula:
V
(1) A=~1+0) _gh , where A is the cross-sectional area V is the volume flow g is the gravity acceleration h is the ~eight of fall A is a correction element which describes the friction in the mater=al, assuming for water a small value which is close to C
The water jet must be assumed to roughly circular and, therefore, its circumference can be calculated on the basis of the formula:
(2) O=;TD=TC 4(1+0) ~ 7 h , where 0 is the circumference D is the diameter of the water jet As it appears from the aforementioned formula, the circumference is proportional not to the height of fall but to the height of fall to power =1/.
According to the invention it is preferred that the shaft be configured so that its cross-sectional area as a function of the fall of height is essentially as defined in the formula above. To make allowance for the friction which occurs when feeding particulate material via a shaft according to the invention, the correction element A must be within the range 0 and 0.2, preferably lower than 0.1.
The shaft may, for example, be made up of a number of pyramidal or conical sections so that the reduction of the cross-sectional circumference of the shaft exhibits a gradual, downwardly decreasing trend. To ensure that the shape of such a shaft does not deviate too much from the formula (1) indicated above, it is preferred that the number of sections incorporated is at least 3, but preferably at least 5, and most preferably at least 10.
However, it is preferred that the reduction of the cross-sectional circumference of the shaft exhibits a continuous downwardly decrease, and that for example the shaft is of a 3_5 trumpet-shaped configuration.
In principle, it will be possible to use the shaft according to the invention fcr conveying any particulate material from one level to a lower level by the action of gravity, and for this purpose the shaft should be of a substantially vertical 5 configuration, with a downwardly reduced cross-section where the reduction of the cross-sectional circumference of the shaft is downwardly decreasing.
The invention will be explained in further details in the followina with reference being made to the drawing, which is diagrammatical, and where Fig. 1 shows a roller press installaticn comprising a feed shaft according to the invention.
In Fig. 1 is seen a roller press installation comprising a roller press 1 with two oppositely rotating rollers 3 and 5.
During the operation of the roller press, the material to be ground is fed from a bin 7 via a feed conveyor 9 and a feed shaft 11 to a grinding zone 13 between the rollers 3 and 5.
According to the invention the depicted shaft is formed with a downwardly reduced cross-section in such a way that the reduction of the shaft"s cross-sectional circumference per height unit is also downwardly decreasing. Ideal_y the shaft is formed with a downwardly decreasing cross-section which is inversely proportional to the steadily downwardly increasing velocity of the material due to the gravity-induced acceleration. 1--lence it will be possible for the material to achieve a velocity close to the velocity of a free fall without admixture of air, allowing the roller press to be operated at higher roller velocities, thereby increasing its rate of production.
The applicant filing the present patent application has conducted tests with a shaft configured in accordance with the aforementioned auidelines, with a final cross section of 0.1 x 0.1- metr=s and a heiaht Of 5 metres, and has recorded a materiai velocity which is close to 10 m/s withcut air admixture.
According to the invention it is preferred that the shaft be configured so that its cross-sectional area as a function of the fall of height is essentially as defined in the formula above. To make allowance for the friction which occurs when feeding particulate material via a shaft according to the invention, the correction element A must be within the range 0 and 0.2, preferably lower than 0.1.
The shaft may, for example, be made up of a number of pyramidal or conical sections so that the reduction of the cross-sectional circumference of the shaft exhibits a gradual, downwardly decreasing trend. To ensure that the shape of such a shaft does not deviate too much from the formula (1) indicated above, it is preferred that the number of sections incorporated is at least 3, but preferably at least 5, and most preferably at least 10.
However, it is preferred that the reduction of the cross-sectional circumference of the shaft exhibits a continuous downwardly decrease, and that for example the shaft is of a 3_5 trumpet-shaped configuration.
In principle, it will be possible to use the shaft according to the invention fcr conveying any particulate material from one level to a lower level by the action of gravity, and for this purpose the shaft should be of a substantially vertical 5 configuration, with a downwardly reduced cross-section where the reduction of the cross-sectional circumference of the shaft is downwardly decreasing.
The invention will be explained in further details in the followina with reference being made to the drawing, which is diagrammatical, and where Fig. 1 shows a roller press installaticn comprising a feed shaft according to the invention.
In Fig. 1 is seen a roller press installation comprising a roller press 1 with two oppositely rotating rollers 3 and 5.
During the operation of the roller press, the material to be ground is fed from a bin 7 via a feed conveyor 9 and a feed shaft 11 to a grinding zone 13 between the rollers 3 and 5.
According to the invention the depicted shaft is formed with a downwardly reduced cross-section in such a way that the reduction of the shaft"s cross-sectional circumference per height unit is also downwardly decreasing. Ideal_y the shaft is formed with a downwardly decreasing cross-section which is inversely proportional to the steadily downwardly increasing velocity of the material due to the gravity-induced acceleration. 1--lence it will be possible for the material to achieve a velocity close to the velocity of a free fall without admixture of air, allowing the roller press to be operated at higher roller velocities, thereby increasing its rate of production.
The applicant filing the present patent application has conducted tests with a shaft configured in accordance with the aforementioned auidelines, with a final cross section of 0.1 x 0.1- metr=s and a heiaht Of 5 metres, and has recorded a materiai velocity which is close to 10 m/s withcut air admixture.
Claims (7)
1. An apparatus for grinding of particulate material which apparatus comprises a roller mill by which the material to be ground is subjected to a pressing action in a zone between opposite, rotating surfaces as well as a shaft for feeding particulate material to the grinding zone of the roller mill, the shaft being of a substantially vertical configuration and with a downwardly reduced cross-section wherein the reduction of the shaft's cross-sectional circumference per height unit is downwardly decreasing.
2. An apparatus according to claim 1 wherein the cross-sectional area of the shaft as a function of the height of fall is in accordance with the formula where A is the cross-sectional area V is the volume flow g is the gravity acceleration h is the height of fall A is within the range 0 and 0.2.
3. An apparatus according to claim 2 wherein A is lower than 0.1.
4. An apparatus according to claim 1 wherein the shaft is made up of at least 3 pyramical or conical sections.
5. An apparatus according to claim 1, 2 or 3 wherein the reduction of the cross-sectional circumference of the shaft exhibits a continuous downwardly decrease.
6. An apparatus according to claim 5 wherein the shaft is of a trumpet-shaped configuration.
7. An apparatus according to any one of claims 1 to 6 wherein the particulate material is cement or cement clinker.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DKPA200000147 | 2000-01-28 | ||
| DKPA200000147 | 2000-01-28 | ||
| PCT/IB2001/000057 WO2001054818A1 (en) | 2000-01-28 | 2001-01-19 | Method and apparatus for grinding of particulate material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2397796A1 CA2397796A1 (en) | 2001-08-02 |
| CA2397796C true CA2397796C (en) | 2009-01-13 |
Family
ID=8159040
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002397796A Expired - Fee Related CA2397796C (en) | 2000-01-28 | 2001-01-19 | Method and apparatus for grinding of particulate material |
Country Status (19)
| Country | Link |
|---|---|
| EP (1) | EP1261431B1 (en) |
| JP (1) | JP2003520676A (en) |
| KR (1) | KR100729026B1 (en) |
| CN (1) | CN1139431C (en) |
| AT (1) | ATE397493T1 (en) |
| AU (1) | AU771192B2 (en) |
| BR (1) | BR0107809A (en) |
| CA (1) | CA2397796C (en) |
| CZ (1) | CZ299850B6 (en) |
| DE (1) | DE60134307D1 (en) |
| DK (1) | DK1261431T3 (en) |
| ES (1) | ES2307582T3 (en) |
| MX (1) | MXPA02007282A (en) |
| PL (1) | PL196219B1 (en) |
| PT (1) | PT1261431E (en) |
| RU (1) | RU2253512C2 (en) |
| TW (1) | TW466136B (en) |
| WO (1) | WO2001054818A1 (en) |
| ZA (1) | ZA200204389B (en) |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE621430A (en) * | 1961-08-26 | |||
| ZA741753B (en) * | 1974-03-18 | 1975-10-29 | De Beers Ind Diamond | Rolls crushers |
| CH624313A5 (en) * | 1977-06-24 | 1981-07-31 | Buehler Ag Geb | |
| US4396158A (en) * | 1981-05-28 | 1983-08-02 | Olsen Jerome A | Device and method for processing hatchery offal |
| DE3525935A1 (en) * | 1985-07-19 | 1987-01-29 | Krupp Polysius Ag | METHOD AND SYSTEM FOR CRUSHING GROUND MATERIAL |
| JPS6320045A (en) * | 1986-07-11 | 1988-01-27 | 宇部興産株式会社 | Grinding equipment |
| FR2620635B1 (en) * | 1987-09-17 | 1992-09-11 | Fives Cail Babcock | PROCESS OF FINE GRINDING OF MINERALS AND CRUSHER FOR THE IMPLEMENTATION OF THIS PROCESS |
| JPH01110838U (en) * | 1988-01-20 | 1989-07-26 | ||
| DE4126899A1 (en) * | 1991-08-14 | 1993-02-18 | Krupp Polysius Ag | METHOD AND APPENDIX FOR CRUSHING SPROEDEM GRILLS |
| DK205591A (en) * | 1991-12-23 | 1993-06-24 | Smidth & Co As F L | PROCEDURE FOR GRINDING PARTICULATED MATERIAL IN A ROLLING PRESSURE, AND DEVICE FOR EXERCISING THE PROCEDURE |
| JPH06285854A (en) * | 1993-03-31 | 1994-10-11 | Hisao Sato | Apparatus for treatment of expanded styrol |
| EP0841860B1 (en) * | 1995-06-13 | 2003-04-02 | Mark H. Sterner | Method and device for preparing dehydrated pea soup |
| ID29450A (en) * | 1998-12-08 | 2001-08-30 | Micro Motion Inc | CORIOLIS MASS FLOW CONTROLLER |
-
2000
- 2000-12-01 TW TW089125627A patent/TW466136B/en not_active IP Right Cessation
-
2001
- 2001-01-19 BR BR0107809-7A patent/BR0107809A/en active Search and Examination
- 2001-01-19 PL PL356139A patent/PL196219B1/en not_active IP Right Cessation
- 2001-01-19 EP EP01900219A patent/EP1261431B1/en not_active Expired - Lifetime
- 2001-01-19 CA CA002397796A patent/CA2397796C/en not_active Expired - Fee Related
- 2001-01-19 CN CNB018038522A patent/CN1139431C/en not_active Expired - Fee Related
- 2001-01-19 CZ CZ20022579A patent/CZ299850B6/en not_active IP Right Cessation
- 2001-01-19 PT PT01900219T patent/PT1261431E/en unknown
- 2001-01-19 WO PCT/IB2001/000057 patent/WO2001054818A1/en active IP Right Grant
- 2001-01-19 ES ES01900219T patent/ES2307582T3/en not_active Expired - Lifetime
- 2001-01-19 KR KR1020027008658A patent/KR100729026B1/en not_active IP Right Cessation
- 2001-01-19 MX MXPA02007282A patent/MXPA02007282A/en active IP Right Grant
- 2001-01-19 AT AT01900219T patent/ATE397493T1/en not_active IP Right Cessation
- 2001-01-19 AU AU23915/01A patent/AU771192B2/en not_active Ceased
- 2001-01-19 DK DK01900219T patent/DK1261431T3/en active
- 2001-01-19 RU RU2002123056/03A patent/RU2253512C2/en not_active IP Right Cessation
- 2001-01-19 JP JP2001554793A patent/JP2003520676A/en active Pending
- 2001-01-19 DE DE60134307T patent/DE60134307D1/en not_active Expired - Fee Related
-
2002
- 2002-05-31 ZA ZA200204389A patent/ZA200204389B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DE60134307D1 (en) | 2008-07-17 |
| ZA200204389B (en) | 2003-08-27 |
| TW466136B (en) | 2001-12-01 |
| WO2001054818A1 (en) | 2001-08-02 |
| ATE397493T1 (en) | 2008-06-15 |
| PL356139A1 (en) | 2004-06-14 |
| DK1261431T3 (en) | 2008-07-21 |
| KR100729026B1 (en) | 2007-06-14 |
| PL196219B1 (en) | 2007-12-31 |
| CA2397796A1 (en) | 2001-08-02 |
| JP2003520676A (en) | 2003-07-08 |
| MXPA02007282A (en) | 2003-02-12 |
| CN1139431C (en) | 2004-02-25 |
| RU2253512C2 (en) | 2005-06-10 |
| BR0107809A (en) | 2002-10-22 |
| KR20020062776A (en) | 2002-07-29 |
| CN1400924A (en) | 2003-03-05 |
| CZ299850B6 (en) | 2008-12-10 |
| CZ20022579A3 (en) | 2003-01-15 |
| PT1261431E (en) | 2008-09-08 |
| AU2391501A (en) | 2001-08-07 |
| EP1261431A1 (en) | 2002-12-04 |
| AU771192B2 (en) | 2004-03-18 |
| EP1261431B1 (en) | 2008-06-04 |
| RU2002123056A (en) | 2004-03-10 |
| ES2307582T3 (en) | 2008-12-01 |
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| EEER | Examination request | ||
| MKLA | Lapsed |