WO2001019522A1 - Method and apparatus for grinding of particulate material - Google Patents

Method and apparatus for grinding of particulate material Download PDF

Info

Publication number
WO2001019522A1
WO2001019522A1 PCT/EP2000/007977 EP0007977W WO0119522A1 WO 2001019522 A1 WO2001019522 A1 WO 2001019522A1 EP 0007977 W EP0007977 W EP 0007977W WO 0119522 A1 WO0119522 A1 WO 0119522A1
Authority
WO
WIPO (PCT)
Prior art keywords
separator
vertical
mill
mill housing
louvre
Prior art date
Application number
PCT/EP2000/007977
Other languages
French (fr)
Inventor
Søren Worre JØRGENSEN
Original Assignee
F L Smidth & Co A/S
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by F L Smidth & Co A/S filed Critical F L Smidth & Co A/S
Priority to AU69962/00A priority Critical patent/AU6996200A/en
Publication of WO2001019522A1 publication Critical patent/WO2001019522A1/en

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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
    • B02C15/00—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
    • B02C23/18—Adding fluid, other than for crushing or disintegrating by fluid energy
    • B02C23/24—Passing gas through crushing or disintegrating zone
    • B02C23/32—Passing gas through crushing or disintegrating zone with return of oversize material to crushing or disintegrating zone
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C15/00—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs
    • B02C2015/002—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs combined with a classifier
    • 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
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding

Definitions

  • the present invention relates to a method for grinding of particulate material such as cement raw materials, cement clinker and similar materials in a vertical mill comprising a mill housing which encases a grinding table being rotatable about a vertical axis, at least one roller being rotatable about a substantially stationary axis, a nozzle ring system surrounding at least parts of the circumference of the grinding table for injecting a gas stream up around the grinding table and ascending up through the mill housing, as well as a separator with a louvre for sorting the material entrained in the gas stream.
  • the invention also relates to a vertical mill for carrying out the method according to the invention.
  • a vertical mill of the aforementioned kind is known, for example, from GB-B- 2214106.
  • This prior art mill functions ideally in accordance with an operating principle in which the material which is ground on the grinding table by the grinding rollers is flung outwards from the rotating grinding table and across the surrounding nozzle ring by means of which finer particles are dispersed and suspended in the conveying gas flowing up through the nozzle ring and are passed to a separator mounted in the top of the mill where the material is sorted into a fine fraction which is discharged from the mill as a finished product and into an insufficiently ground coarser fraction which is returned to the grinding table for renewed grinding.
  • the average vertical gas velocity through the mill housing to the louvre of the separator is at least 7 m/s, preferably at least 9 m/s.
  • a vertical mill for use in the method is characterised in that the cross-sectional area lying between the mill housing and the separator decreases from a horizontal plane immediately above the roller or rollers to a horizontal plane at the louvre ofthe separator.
  • the efficiency ofthe combined separation process in the mill housing and the separator can be enhanced. This is due to the fact that the separation of fine and coarse material particles will take place to a greater extent in the separator and to a lesser extent in the mill housing when the vertical mill is operated with a vertical gas velocity increasing from at least 7 m/s.
  • a vertical mill comprising a grinding table 1 which is rotatable about its central vertical axis and driven via a gear unit 2. Rolling on the grinding table 1 are grinding rollers 3 which are mounted on shafts (not shown) and urged down towards the grinding table 1 by means of known, but now shown, pull or pressure means.
  • the vertical mill is encased by a mill housing 5 which at its upper end has a built-in separator 6.
  • the separator 6 has in its inlet a louvre 7 which may be adjustable.
  • the separator may also comprise a rotor (not shown) which is fitted inside the louvre and is rotatable about a vertical axis.
  • the separator 6 is equipped with an outlet hopper 8 with an outlet 9 extending down towards the grinding table 1.
  • the grinding table 1 is surrounded by a nozzle ring 10 through which conveying gas flows from a chamber 11 under the nozzle ring and grinding table. Gas is fed to the chamber 11 from a gas supply duct 12.
  • Fresh, unground material to be fed to the vertical mill is introduced into the vertical mill through a supply duct 13 ending at the top of a feed pipe 14 which is fitted coaxially with the grinding table 1 and at some distance above its central section 15.
  • the material which is introduced to the vertical mill through the supply duct 13 passes down through the feed pipe 14 to the central part 15 of the grinding table wherefrom, resulting from the rotation of the grinding table in use, the material is flung outwards and ground under the grinding rollers 3.
  • the ground material is flung onward beyond the nozzle ring 10 and scavenged by the conveying gas which flows up through the nozzle ring 10.
  • Particles which are too heavy to be suspended in the conveying gas and carried up through the vertical mill drop through the nozzle ring and are discharged from the space under the nozzle ring via an outlet 16 wherefrom the particles are lifted to the supply duct 13 by means of an external conveyor indicated at 17 and returned to the vertical mill for renewed grinding.
  • the design principle of the vertical mill involves decreasing the free cross-sectional area in a horizontal plane from the mill housing to the louvre of the separator from a horizontal plane immediately above the rollers 3 to a horizontal plane at the louvre 7 of the separator.
  • the upwardly decreasing cross-sectional area is obtained by means of a hopper 8 which is designed with an increasing cross-sectional area in the upwards direction towards the separator 6.
  • the wall of the mill housing 5 may be of a conical configuration with a decreasing diameter or the cross-sectional area in the direction towards the separator or the mill housing may be equipped with internal fittings.
  • the vertical gas velocity through the vertical mill is at least 7 m/s, preferably at least 9 m/s.

Abstract

Described is a method as well as a vertical mill for grinding of particulate material such as cement raw materials, cement clinker and similar materials, which vertical mill comprises a mill housing (5) which encases a grinding table (1) rotatable about a vertical axis. At least one roller (3) is rotatable about a substantially stationary axis, and a nozzle ring system (10) surrounds at least parts of the circumference of the grinding table (1) for injecting a gas stream up around the grinding table and ascending up through the mill housing. A separator (6) with louvre (7) sorts the material entrained in the gas stream. The method is peculiar in that the average vertical gas velocity in the plane between the mill housing (5) and the separator (6) increases from a horizontal plane immediately above the roller or rollers (3) to a horizontal plane at the louvre (7) of the separator and in that the vertical gas velocity through the mill housing (5) to the louvre (7) of the separator is at least 7 m/s, preferably at least 9 m/s. Such a method enhances the efficiency of the combined separation process in the mill housing and the separator.

Description

METHOD AND APPARATUS FOR GRINDING OF PARTICULATE MATERIAL
The present invention relates to a method for grinding of particulate material such as cement raw materials, cement clinker and similar materials in a vertical mill comprising a mill housing which encases a grinding table being rotatable about a vertical axis, at least one roller being rotatable about a substantially stationary axis, a nozzle ring system surrounding at least parts of the circumference of the grinding table for injecting a gas stream up around the grinding table and ascending up through the mill housing, as well as a separator with a louvre for sorting the material entrained in the gas stream. The invention also relates to a vertical mill for carrying out the method according to the invention.
A vertical mill of the aforementioned kind is known, for example, from GB-B- 2214106. This prior art mill functions ideally in accordance with an operating principle in which the material which is ground on the grinding table by the grinding rollers is flung outwards from the rotating grinding table and across the surrounding nozzle ring by means of which finer particles are dispersed and suspended in the conveying gas flowing up through the nozzle ring and are passed to a separator mounted in the top of the mill where the material is sorted into a fine fraction which is discharged from the mill as a finished product and into an insufficiently ground coarser fraction which is returned to the grinding table for renewed grinding.
However, in practice it has emerged that not only does a sorting process take place in the separator, but also in the mill housing itself. In terms of energy usage, this is undesirable since the effectiveness of the separation process in the separator must be considered as being superior to that effected in the mill housing. It is an object of the present invention to provide a method for grinding of particulate method in a vertical mill whereby the aforementioned disadvantage is reduced.
This is achieved by a method of the kind mentioned in the introduction and being characterised in that the vertical gas velocity, calculated as the average vertical gas velocity over the cross-sectional area lying between the mill housing and the separator, increases from a horizontal plane immediately above the roller or rollers to a horizontal plane at the louvre of the separator.
Preferably, the average vertical gas velocity through the mill housing to the louvre of the separator is at least 7 m/s, preferably at least 9 m/s. A vertical mill for use in the method is characterised in that the cross-sectional area lying between the mill housing and the separator decreases from a horizontal plane immediately above the roller or rollers to a horizontal plane at the louvre ofthe separator.
Thus the efficiency ofthe combined separation process in the mill housing and the separator can be enhanced. This is due to the fact that the separation of fine and coarse material particles will take place to a greater extent in the separator and to a lesser extent in the mill housing when the vertical mill is operated with a vertical gas velocity increasing from at least 7 m/s.
The invention will now be described in detail with reference made to the accompanying figure which is a diagrammatical drawing depicting a vertical section through a vertical mill.
In the figure is shown a vertical mill comprising a grinding table 1 which is rotatable about its central vertical axis and driven via a gear unit 2. Rolling on the grinding table 1 are grinding rollers 3 which are mounted on shafts (not shown) and urged down towards the grinding table 1 by means of known, but now shown, pull or pressure means.
The vertical mill is encased by a mill housing 5 which at its upper end has a built-in separator 6. The separator 6 has in its inlet a louvre 7 which may be adjustable. The separator may also comprise a rotor (not shown) which is fitted inside the louvre and is rotatable about a vertical axis. At its lower end the separator 6 is equipped with an outlet hopper 8 with an outlet 9 extending down towards the grinding table 1.
The grinding table 1 is surrounded by a nozzle ring 10 through which conveying gas flows from a chamber 11 under the nozzle ring and grinding table. Gas is fed to the chamber 11 from a gas supply duct 12.
Fresh, unground material to be fed to the vertical mill is introduced into the vertical mill through a supply duct 13 ending at the top of a feed pipe 14 which is fitted coaxially with the grinding table 1 and at some distance above its central section 15.
The material which is introduced to the vertical mill through the supply duct 13 passes down through the feed pipe 14 to the central part 15 of the grinding table wherefrom, resulting from the rotation of the grinding table in use, the material is flung outwards and ground under the grinding rollers 3.
The ground material is flung onward beyond the nozzle ring 10 and scavenged by the conveying gas which flows up through the nozzle ring 10. Particles which are too heavy to be suspended in the conveying gas and carried up through the vertical mill drop through the nozzle ring and are discharged from the space under the nozzle ring via an outlet 16 wherefrom the particles are lifted to the supply duct 13 by means of an external conveyor indicated at 17 and returned to the vertical mill for renewed grinding.
Lighter particles of ground material which can be suspended in and carried up through the vertical mill by the conveying gas stream are diverted, as indicated by means of arrows, to the louvre 7 in the inlet ofthe separator and into the separator 6 in which the material is divided into a fine fraction which is extracted from the vertical mill via a top outlet 18 and a coarse fraction which falls down along the sides in the outlet hopper 8, out through the outlet 9 and down into the feed pipe 14.
In order to reduce the sorting process which takes place in the mill housing and hence to achieve benefits from a reduction of energy usage, the design principle of the vertical mill involves decreasing the free cross-sectional area in a horizontal plane from the mill housing to the louvre of the separator from a horizontal plane immediately above the rollers 3 to a horizontal plane at the louvre 7 of the separator. In the embodiment shown the upwardly decreasing cross-sectional area is obtained by means of a hopper 8 which is designed with an increasing cross-sectional area in the upwards direction towards the separator 6. Alternatively, the wall of the mill housing 5 may be of a conical configuration with a decreasing diameter or the cross-sectional area in the direction towards the separator or the mill housing may be equipped with internal fittings. The latter option would be particularly advantageous for converting existing mills. During the operation of the vertical mill, this will lead to an increase in the gas velocity up through the vertical mill from a horizontal plane immediately above the rollers 3 to a horizontal plane at the louvre 7 of the separator. In order to substantially reduce the sorting process in the mill housing while simultaneously ensuring low energy usage, it is preferred that the vertical gas velocity through the vertical mill is at least 7 m/s, preferably at least 9 m/s.

Claims

1. A method for grinding of particulate material such as cement raw materials, cement clinker and similar materials in a vertical mill comprising a mill housing (5) which houses a grinding table (1 ) rotatable about a vertical axis, at least one grinding roller (3) rotatable about a substantially stationary axis, a nozzle ring system (10) surrounding at least parts of the circumference of the grinding table (1 ) for injecting a gas stream up around the grinding table and ascending up through the mill housing, and a separator (6) with a louvre (7) for sorting the material entrained in the gas stream, characterised in that the vertical gas velocity, calculated as the average vertical gas velocity over the cross-sectional area lying between the mill housing (5) and the separator increases from a horizontal plane immediately above the roller (3) to a horizontal plane at the louvre (7) of the separator.
2. A method according to claim 1 , in which the average vertical gas velocity through the mill housing (5) to the louvre (7) of the separator is at least 7 m/s.
3. A method according to claim 1 , in which the vertical gas velocity through the mill housing (5) to the louvre (7) of the separator is at least 9 m/s.
4. A vertical mill for carrying out the method according to claim 1 , comprising a mill housing (5) which houses a grinding table (1 ) rotatable about a vertical axis, at least one grinding roller (3) rotatable about a substantially stationary axis, a nozzle ring system (10) surrounding at least parts of the circumference of the grinding table (1 )for injecting a gas stream up around the grinding table and ascending up through the mill housing, and a separator (6) with a louvre (7) for sorting the material entrained in the gas stream, characterised in that the cross-sectional area lying between the mill housing (5) and the separator decreases from a horizontal plane immediately above the roller or rollers (3) to a horizontal plane at the louvre (7) of the separator.
5. A vertical mill according to claim 4, further including means for causing the average vertical gas velocity through the mill housing to be at least 7 m/s.
PCT/EP2000/007977 1999-09-14 2000-08-16 Method and apparatus for grinding of particulate material WO2001019522A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU69962/00A AU6996200A (en) 1999-09-14 2000-08-16 Method and apparatus for grinding of particulate material

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DKPA199901295 1999-09-14
DKPA199901295 1999-09-14

Publications (1)

Publication Number Publication Date
WO2001019522A1 true WO2001019522A1 (en) 2001-03-22

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PCT/EP2000/007977 WO2001019522A1 (en) 1999-09-14 2000-08-16 Method and apparatus for grinding of particulate material

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WO (1) WO2001019522A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103406186A (en) * 2013-08-09 2013-11-27 成都建筑材料工业设计研究院有限公司 Technology and device for baking and grinding high-moisture chalk through vertical mill
CN104907150A (en) * 2015-05-05 2015-09-16 铜陵海源超微粉体有限公司 High-moisture vertical mill drying in-series grinding process

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2117667A (en) * 1982-01-23 1983-10-19 Steag Ag Coal-milling plant with grit recirculation and separation of pyrite and mine-waste
DE3443808A1 (en) * 1983-11-30 1985-06-05 Mitsubishi Jukogyo K.K. Process for grinding solid materials
FR2599276A1 (en) * 1986-05-27 1987-12-04 Pfeffer Ag Geb Comminution installation with air flow
EP0283682A2 (en) * 1987-03-24 1988-09-28 Mitsubishi Jukogyo Kabushiki Kaisha Roller mill
GB2214106A (en) * 1987-12-24 1989-08-31 Smidth & Co As F L Edge runner mill feed control
JPH06296886A (en) * 1993-04-16 1994-10-25 Sumitomo Metal Ind Ltd Production of fine powder of granulated blastfurnace slag

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2117667A (en) * 1982-01-23 1983-10-19 Steag Ag Coal-milling plant with grit recirculation and separation of pyrite and mine-waste
DE3443808A1 (en) * 1983-11-30 1985-06-05 Mitsubishi Jukogyo K.K. Process for grinding solid materials
FR2599276A1 (en) * 1986-05-27 1987-12-04 Pfeffer Ag Geb Comminution installation with air flow
EP0283682A2 (en) * 1987-03-24 1988-09-28 Mitsubishi Jukogyo Kabushiki Kaisha Roller mill
GB2214106A (en) * 1987-12-24 1989-08-31 Smidth & Co As F L Edge runner mill feed control
GB2214106B (en) 1987-12-24 1991-06-26 Smidth & Co As F L Vertical roller mill
JPH06296886A (en) * 1993-04-16 1994-10-25 Sumitomo Metal Ind Ltd Production of fine powder of granulated blastfurnace slag

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 1995, no. 01 28 February 1995 (1995-02-28) *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103406186A (en) * 2013-08-09 2013-11-27 成都建筑材料工业设计研究院有限公司 Technology and device for baking and grinding high-moisture chalk through vertical mill
CN104907150A (en) * 2015-05-05 2015-09-16 铜陵海源超微粉体有限公司 High-moisture vertical mill drying in-series grinding process

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Publication number Publication date
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