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

Definitions

• the present invention relates to a method for grinding of particulate material such as cement raw materials, ceraenc clinker or similar materials, in a roller mill, such as a roller press, ring-roller mill, vertical mill or a similar unit, by subjecting the material to pressing action in a zone between opposite, rotating surfaces where the material is directed to the grinding zone via a eed shaf .
• the invention also relates to an apparatus for carrying out the method according to the invention.
• Such operating problems may be ascribable to many different causes.
• One explanation could be the difficulty cf achieving an acceleration of the material which 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.
• the capability of the rollers is restricted to a very short range of operation, thereby severely 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.
• 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.
• 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 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 the 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 than 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.
• the water flow rate is quite small, with the width of the water jet corresponding roughly to the outlet.
• 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 function of the height of fall can be expressed by means of the formula:
• A is the cross-sectional area
• V is the volume flow g is the gravity acceleration h is the height of fall
• ⁇ is a correction element which describes the friction in the material, 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 cf the formula:
• the circumference is proportional not to the height of fall but to the height of fall to power ⁇ A.
• 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.
• the correction element ⁇ 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.
• the number of sections incorporated is at least 3, but preferably at least 5, and most preferably at least 10.
• the reduction of the cross- sectional circumference of the shaft exhibits a continuous downwardly decrease, and that for example the shaft is of a trumpet-shaped configuration.
• the shaft according to the invention for 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 configuration, with a downwardly reduced cross-section where the reduction of the cross-sectional circumference of the shaft is downwardly decreasing.
• Fig. 1 shows a roller press installation comprising a feed shaft 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.
• 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.
• the applicant filing the present patent application has conducted tests with a shaft configured in accordance with the a orementioned guidelines, with a final cross section cf 0.1 x 0.1 metres and a height of 5 metres, and has recorded a material velocity which is close to 10 m/s without air admixture .

Landscapes

• 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)

Priority Applications (9)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8159040

Family Applications (1)

Country Status (19)

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Citations (1)

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• 2000
  • 2000-12-01 TW TW089125627A patent/TW466136B/zh not_active IP Right Cessation
• 2001
  • 2001-01-19 BR BR0107809-7A patent/BR0107809A/pt active Search and Examination
  • 2001-01-19 JP JP2001554793A patent/JP2003520676A/ja active Pending
  • 2001-01-19 MX MXPA02007282A patent/MXPA02007282A/es active IP Right Grant
  • 2001-01-19 KR KR1020027008658A patent/KR100729026B1/ko not_active Expired - Fee Related
  • 2001-01-19 CZ CZ20022579A patent/CZ299850B6/cs not_active IP Right Cessation
  • 2001-01-19 DK DK01900219T patent/DK1261431T3/da active
  • 2001-01-19 WO PCT/IB2001/000057 patent/WO2001054818A1/en not_active Ceased
  • 2001-01-19 PT PT01900219T patent/PT1261431E/pt unknown
  • 2001-01-19 CA CA002397796A patent/CA2397796C/en not_active Expired - Fee Related
  • 2001-01-19 EP EP01900219A patent/EP1261431B1/en not_active Expired - Lifetime
  • 2001-01-19 RU RU2002123056/03A patent/RU2253512C2/ru not_active IP Right Cessation
  • 2001-01-19 AT AT01900219T patent/ATE397493T1/de not_active IP Right Cessation
  • 2001-01-19 AU AU23915/01A patent/AU771192B2/en not_active Ceased
  • 2001-01-19 CN CNB018038522A patent/CN1139431C/zh not_active Expired - Fee Related
  • 2001-01-19 DE DE60134307T patent/DE60134307D1/de not_active Expired - Fee Related
  • 2001-01-19 PL PL356139A patent/PL196219B1/pl not_active IP Right Cessation
  • 2001-01-19 ES ES01900219T patent/ES2307582T3/es not_active Expired - Lifetime
• 2002
  • 2002-05-31 ZA ZA200204389A patent/ZA200204389B/xx unknown

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