CN1400924A - Method and apparatus for grinding of particulate material - Google Patents

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 shaft's 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.

Description

The method and apparatus that is used for grinding of particulate material

The present invention relates to a kind of like this method, promptly, by sheeted product in the zone between the surface in relative rotation that material is directed into milling zone via feed shaft, roller press such as roll squeezer, ring roller mill, vertical mill or similar device in grinding of particulate material such as cement raw material, clinker or similar material.The invention still further relates to a kind of device of implementing the inventive method.

The method and apparatus of mentioned kind belongs to prior art.

In recent years, the development on the grinding technique mainly is devoted to improve the cost efficiency of the operation of milling.At this on the one hand, primary focus is to improve the operating efficiency of grinding step and reduces the investment cost of grinder with respect to its capacity rating.A kind of method that is widely used in reducing investment cost relates to service speed and even the productivity ratio that improves machine.Much less, the service speed of machine only can be added to certain value, moreover also has such admitted facts, that is, if indiscriminately ad. as one wishes increase the peripheral speed of roller, just might go wrong in the operation of for example roll squeezer.

Such operational issue is attributed to many different reasons.A kind of being interpreted as is difficult to make the acceleration of waiting to be ground the material in roll squeezer to reach and the corresponding degree of the peripheral speed of roller.This acceleration of material normally by means of roller by contacting with roller physics and/or effect by gravity realizes.But, the ability of roller is limited in the very short working range, thereby has strictly limited acceleration, and gravity or the frictional force that is resisted against on the axle by material balance out in axle, and/or is balanced out by the frictional force of material self.Simultaneously, the acceleration that realizes in the tradition axle also can bring the impurity of significant air, and this does not wish to take place, and this point can have a negative impact to grinding step equally.The vertical shaft that use has circle or rectangular cross section and has same cross-sectional area along whole length, gravity is accelerated to material at a high speed, but in the case, also can increase the distance between the particle simultaneously, thereby reduce the density of material and included air plankton.By using the axle of pyramid or conical structure, can keep the gap between the particle, but in the axle of the type, material will be subjected to the influence of frictional force, institute is influenced so big so that speed final acquisition is very little.In the axle of this routine, section girth is the linear decrease function of height.Thereby the reduction of the section girth of each height unit still remains unchanged with respect to these axles.

The object of the present invention is to provide a kind of method and apparatus that overcomes above-mentioned defective.

This purpose is to realize that by a kind of like this method of mentioning it is characterized in that, the material in the feed shaft is accelerated to required speed by means of gravity, and can not comprise intrinsic contaminants in the air.Apparatus of the present invention are characterised in that the reduction of the axle section girth of each height unit is successively decreased downwards.

Surprisingly, the structure of described feed shaft confirms, specifies the material on the height of drop can obtain high speed, and this is practicable, can not comprise air plankton in material.Thereby just realized this point, that is, and the close speed of speed that material reaches in the time of can obtaining with the individual particle free-falling.

Material can be accelerated to speed greater than 1.5m/s.But, preferred feed can be accelerated to speed greater than 5m/s, is preferably greater than 10m/s.

Can for example understand an example of cross section characteristic of the present invention from the current form of free-falling from the tap of slow operation.At the top, in the outlet of tap, the flow velocity of water is very little, and the width of current is roughly corresponding with outlet.Along with further moving downward of current, gravity has improved the flow velocity of water, but since the water that runs through flow with and to run through the density of current also identical, so this means that the cross section of current is less.So, current will obtain near hyp shape, can be by following equation expression as the feature of the cross-sectional area of height of drop function: $\left(1\right)A=(1+\mathrm{\Δ})\frac{\stackrel{\·}{V}}{\sqrt{2\mathrm{gh}}}$ , wherein A is that cross-sectional area is that volume flow g is that acceleration of gravity h is a height of drop

Δ is to proofread and correct unit, its description be frictional force in the material, suppose that glassware for drinking water has to approach 0 smaller value.

Current must be presumed to be and be roughly circle, and therefore, its girth can calculate based on following formula: $\left(2\right)O=\mathrm{\πD}=\mathrm{\π}\sqrt{\frac{4}{\mathrm{\π}}(1+\mathrm{\Δ})\frac{\stackrel{\·}{V}}{\sqrt{2\mathrm{gh}}}},$ Wherein

O is a girth

D is the diameter of current

Can find out significantly that from above-mentioned formula girth is not directly proportional with height of drop but is directly proportional with 1/4 power of height of drop.

According to the present invention, the preferred axle of structure so promptly, is pressed top formula basically as its cross-sectional area of height of drop function and is limited.In order to deduct the frictional force that when supplying with granule materials, occurs, proofread and correct the scope that first Δ must be positioned at 0-0.2, preferably less than 0.1 by axle of the present invention.

For example, axle can be made of many pyramids or conical section, and the reduction of axle section girth just presents the trend of progressively successively decreasing downwards like this.For the shape that guarantees this does not differ greatly with above-mentioned formula (1), preferred the number in conjunction with section is 3 at least, but more preferably is 5 at least, most preferably is 10 at least.

But, the reduction of preferred axes section girth is to successively decrease downwards continuously, and for example this axle is flaring structure.

Say in principle, can utilize effect that axle of the present invention relies on gravity that any granule materials highly is transported on the lower height from one, for this reason, this should have the structure of perpendicular, and having the cross section of downward reduction, the reduction of its axis section girth is successively decreased downwards.

The present invention will be described in more detail below with reference to the accompanying drawing that briefly shows, wherein:

Fig. 1 shows a kind of roll squeezer device, and this device comprises the feed shaft of a basic invention.

A bench roller press device as can be seen from Figure 1, it comprises a roll squeezer 1, it has two rollers 3 and 5 in relative rotation.In roll squeezer operating period, material to be ground supplies to milling zone 13 between roller 3 and 5 by infeed conveyors 9 and feed shaft 11 from hopper 7.

According to the present invention, the axle of being described forms a cross section of reduction downwards in the following manner, that is, the reduction of the section girth of the axle of each height unit is also successively decreased downwards.In theory, this forms such cross section that successively decreases downwards, that is, it quickens because of gravity causes to be inversely proportional to the stable speed that increases progressively downwards of material.Therefore, material just can obtain to approach the speed of free-falling speed, and does not have air plankton, thereby allows roll squeezer with higher roller speed operation, improves its productivity ratio thus.

The applicant of application present patent application adopts according to the axle of above-mentioned policy structure and has done multinomial experiment, and wherein last cross section is 0.1m * 0.1m, is 5m highly, and the material speed that is write down approaches 10m/s, does not have air plankton.

Claims (9)

1. One kind in roller press (1) by sheeted product in the zone between the surface in relative rotation (13) that material is directed into milling zone via feed shaft (11) grinding of particulate material such as the method for cement raw material, clinker or similar material, it is characterized in that, material in this feed shaft (11) is accelerated to required speed by means of gravity, can not produce the intrinsic contaminant of air.
2. 2. the method for claim 1 is characterized in that, material is accelerated to speed greater than 1.5m/s.
3. 3. the method for claim 1 is characterized in that, material is accelerated to speed greater than 5m/s.
4. 4. the method for claim 1 is characterized in that, material is accelerated to speed greater than 10m/s.
5. 5. device of implementing the method according to any one of the preceding claims, this device comprises that a roller press (1) and one are used for granule materials is supplied to the axle (11) of the milling zone (13) of this roller press, this axle (11) has upright basically structure, and has a cross section of downward reduction, it is characterized in that the reduction of the section girth of this of each height unit spool is successively decreased downwards.
6. 6. device as claimed in claim 5, abide by following formula as this cross-sectional area of height of drop function: $A=(1+\mathrm{\Δ})\frac{\stackrel{\·}{V}}{\sqrt{2\mathrm{gh}}}$ , wherein A is that cross-sectional area is that volume flow g is that acceleration of gravity h is the scope that the height of drop Δ is positioned at 0-0.2, preferably less than 0.1.
7. 7. device as claimed in claim 5 is characterized in that, this axle is made of at least 3 pyramids or conical section.
8. 8. as claim 5 or 6 described devices, it is characterized in that the reduction of this section girth shows as continuously successively decreases downwards.
9. 9. device as claimed in claim 8 is characterized in that, this axle is flaring structure.

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