Kawasaki Jukogyo Kabushiki Kaisha

Taiheiyo Cement Corporation

Other

Chichibu Cement Co., Ltd.

Seisuke Sawamura

Hiroshi Ueda

Kanzaburo Sutoh

Mitsuaki Murata

Fuminori Ando

Yoshihiro Mitsuda

Akihiko Takayama

Isao Hashimoto

Yuji Yamamoto

Mitsunari Ichikawa

Kanzaburo Sutou

Ryuichi Okamura

Tsutomu Hirobe

Tsuneichi Shitara

A method of grinding cement clinkers and a cement clinker grinding apparatus having a vertical roller mill are provided. In the method, feed material is ground by a table and rollers. Next, substantially all the resultant ground material is taken out from an underside of the table and then converted to a separator for classifying the ground material by a bucket elevator. The resultant coarse powder provided by the separator is returned to a center of the table. In grinding, an pressing force of each of the rollers onto the table is selected so that a roller pressure per full sectional area of the roller ranges from 10 to 15 kg/cm,. Further, a circulation quantity of the coarse powder to be returned to the vertical roller mill is selected from 100 to 300% of the feed material charged into the center of the table. And the liquid of 0.5 to 3% of the feed material to be ground such as water alone or a mixture of water and diethylene glycol is sprayed on the only frictional grinding zone which is positioned outside a position where a relative speed between said table and each of said rollers is equal to zero, in the radial direction of said table. By spraying the liquid on the only frictional grinding zone, the materials are involved firmly between the table and the roller to form the layer of the ground materials, so that the vibration of the roller and table are restrained

Cement clinker grinding method using vertical roller mill and apparatus

The grinding efficiency can be improved by use of a vertical roller mill, while reducing the energy consumption and improving the product quality. The disclosed cement clinker grinding apparatus comprises a closed circuit for conveying the ground material from the vertical roller mill (21) to the external separator (28) by the bucket elevator (29), for classifying the conveyed material into coarse powder and fine powder, and further for returning the classified coarse powder into the vertical roller mill (21). That is, a part of the ground material conveyed by the bucket elevator (29) is divided by the distributing damper (32) and then directly returned to the vertical roller mill (21). Since the ground material are not conveyed by air flow conveyance (i.e., air sweep), it is possible to prevent an increase of power consumption of the suction fan (31). Further, since a part of the ground material is distributed by the distributing damper and then further ground again by the vertical roller mill, it is possible to obtain an optimum particle size distribution of the cement products, so that the cement quality can be improved.

Cement clinker grinding apparatus using vertical roller mill and its

A fluidized-bed classifier has a vessel defining a space divided into an upper fluidized-bed chamber and a lower gas chamber by a perforated dispersion plate having the shape of a funnel. Rising currents of a gas, such as air, are blown through the dispersion plate into the upper fluidized-bed chamber to produce a fluidized bed of a particulate material over the dispersion plate. The lower gas chamber is divided into a first gas chamber and a second gas chamber by a partition plate. The gas is supplied into the first air chamber so that rising gas currents of a velocity necessary for fluidizing coarse particles contained in the particulate material fed into the vessel are blown from the first air chamber through the dispersion plate into the fluidized-bed chamber. The gas is supplied into the second air chamber so that rising gas currents of a velocity lower than the velocity of the rising gas currents blown from the first air chamber into the fluidized-bed chamber are blown into the fluidized-bed chamber so that coarse particles contained in the particulate material are not fluidized and does not flow together with fine particles into a fine particle discharge chute.

Fluidized-bed classifier

A grinding apparatus includes a roller mill in which material particles are pre-ground, a tube mill connected to the roller mill through a fluidized-bed-type classifying device in which the material particles are classified by size and a circulation line is connected between the classifying device and the roller mill, wherein a fluidized portion of the pre-ground particles, which consists of a fine material component is fed into a tube mill, a remaining portion of the pre-ground particles, which consists of course material and some amount of fine material not fed into the tube mill is returned to the roller mill through the circulation line where the remaining portion of the pre-ground particles is again crushed together with newly fed material particles in the roller mill. The fluidized-bed-type classifying device is provided with a first chute through which the fine material component flows out to the tube mill and a second chute connected to the circulation line through which the remaining portion is returned to the roller mill. The inner hollow space of the fluidized-bed-type classifying device is divided into an air introduction section and a fluidized bed section by a porous partition plate arranged horizontally with inclination toward the second chute. The fluidized bed section communicates with both the tube mill and the roller mill and the air introduction section communicates with the material fluidizing air which has a controllable flow rate.

Method and apparatus for grinding material particles

Materials such as cement clinker are crushed by utilizing a crushing apparatus including a vertical roller mill provided with a rotatable table and a plurality of rollers and a distributing device for distributing materials preliminarily crushed by the vertical roller mill. The materials to be crushed is fed into the vertical roller mill, the materials are crushed between the table and the rollers by a pressing force applied to the rollers and substantially the whole amount of the crushed materials is then taken out from the vertical roller mill and conveyed to the distributing device. The crushed materials once conveyed to the distributing device is returned partially as they are to the vertical roller mill and again crushed together with the materials newly fed into the vertical roller mill. The materials are returned to the vertical roller mill by about 20% or more in weight ratio with respect to the newly fed materials when cement clinker is utilized as the materials to be crushed. The returning amount of the crushed materials are controlled in accordance with a power consumption of the rotatable table of the vertical roller mill, and the pressing force of the rollers is controlled in accordance with a power consumption of the rotatable table of the vertical roller mill. The crushed materials are fed to a tube mill installed downstream the vertical roller mill for carrying out a secondary crushing operation.

Crushing apparatus and crushing method

Growing community of inventors

Akashi, Japan

Seisuke Sawamura