DE102007030896A1 - Method and associated good bed roller mill for the continuous comminution of brittle material to be ground - Google Patents

Abstract

The invention relates to a method for the continuous comminution of brittle material to be crushed, in particular ore, in which the ground material to be comminuted is guided through the gap of two counter-rotating rollers, wherein the roller casings have embedded hard bodies for forming an autogenous wear protection. Moreover, the invention relates to a roller mill corresponding to the implementation of the method.

Description

The The invention relates to a method for continuous comminution brittle ground material, in particular ore, in which that too comminuting regrind through the gap between two opposing rotating rollers is performed, the roller shells stored for the formation of an autogenous wear protection Have hard body. Moreover, the invention relates a corresponding to the implementation of the method Gutbettwalzenmühle.

In roll mills, brittle material to be ground is introduced into the nip, by which the two rotatably mounted, counterrotatable rolls are separated from one another, where they are subjected to pressure comminution in the material bed. Depending on the hardness of the material to be comminuted, the roll mantle, like the roll main body, is subjected to a very considerable load due to wear and continuous flexing movements of the entire roll. To minimize the wear of the roll shell through the grindable material to be shredded, it is from the DE 40 36 040 A1 known to provide the roll shell with embedded hard bodies, wherein the hard body protrude from the surface of the roll shell. In the space between adjacent hard bodies of the surface of the roll shell is stored in the use of the roll mill, the grinding material to be crushed, wherein a layer is formed which is fixed on the roll shell by the hard body and thus serves as the actual surface of the roll shells. Training and strength of these autogenous wear protection layers are dependent on various material properties, such as the fracture characteristics and the moisture of the ground material to be crushed. The individual particles of the ground material drawn into the nip are then comminuted in a bed of material, ie in a compressed between two armored roll surfaces bulk material when using a high pressure, which is referred to the Gutbettzerkleinerung.

Provided the humidity of essential parameters for training a good bed is because the moisture through adhesion forces between the individual particles of the ground material to be comminuted holding them together, it is necessary that the to be crushed Ground material has a certain minimum moisture. This is in the Usually unproblematic. But especially dry materials be comminuted by a good bed roller mill, so has It turned out that the layer of the material to be crushed is not formed on the surface of the roll mantle and thus it does not come to the benefits of having an autogenous wear protection layer on the surface of the roller mill offers.

For especially dry materials, ie those that absorb moisture from below two percent, it was observed that the desired Good bed or the autogenous wear protection layer actually not or insufficiently educated.

Such Materials are found, for example, in over-mining iron or other ores originating from very dry areas.

There in desert areas, the moistening of the to be ground Bans good because of the ever-present lack of water there, It is an object of the invention, a method and an associated Roller mill for continuous comminution especially dry and brittle material available too put.

The inventive object is achieved through the use of a wetted good bed on the roll surface. Further advantageous embodiments of the invention will become apparent from the corresponding to method claim 1 dependent claims.

A Another object of the invention is a roll mill for carrying out the inventive Provide process.

These The object is achieved in that in addition to a first material application for the regrind, at least a second application of material is arranged, which liquid and / or, a moistened regrind fraction and / or a Mahlgutfraktion with respect to the material to be ground applied changed composition on the rollers.

According to the invention, it is proposed to use a moistened good bed on the roll surface. In contrast to the known use of a good bed on the roll surface, which consists of the grinding stock itself to be comminuted, it is proposed according to the invention to use a moist bed of good quality against the material to be comminuted on the roll surface. If that is to be shredded Grind even wet, the use of a special wetted Gutbettts on the roll surface is not necessary. However, if the comminuted material to be comminuted has a particular dryness or in its state has only a slight tendency to form a Gutbettts or an autogenous wear protection layer, it has proved to be advantageous if a moist or moistened Gutbett is used on the roll surface.

One damp or moistened good bed can be obtained by by the rollers with different fractions of material applied become. This is the larger fraction to crushing regrind and the smaller fraction for example water, a moisture-added fraction of the ground material to be comminuted or a fraction containing other substances or mixtures of substances of the millbase.

In Advantageously, the invention, the roller with wet or moistened regrind is applied, the wet regrind continues is applied to the rollers from the nip and that too crushing regrind is added directly into the nip. there the wet millbase is in only a small concentration on the roll mill given, so that forms an autogenous wear protection and this used for crushing the drier grind becomes. This method has the advantage of having a substantial lower amount of moisture in the total amount of the crushed Mahlguts the rolling mill can be operated without waived the benefits of autogenous wear protection must become.

in this connection it is possible, the smaller and moister Mahlgutfraktion but it is, too, with the drier regrind fraction possible, different for different factions Choose places of application on the roller, so that the Moist millbase under the drier regrind on the roll surface comes to rest and so as a wear protection layer for the dry regrind serves.

In Advantageous embodiment of the invention, the fraction, the for the formation of the wear protection layer is thought clay, clay, fine sand or other materials, the one Have lumpiness, be attached to the smaller Fraction even more for the formation of a permanent wear protection layer inclines.

In Particularly advantageous embodiment of the invention is liquid sprayed on the roll surface and the entire Grindstock fraction to be comminuted is applied in a known manner to the Roll mill pitched. The advantage of this is one particularly simple modification of existing roll mills, since these only a short distance from the nip with water need to be sprayed so that the on the roll surface liquid present together with the to be comminuted Grist forms a bed of good.

there it has proved to be advantageous if water, seawater, sewage, agricultural waste, industrial wastewater and / or industrial liquid wastes as a liquid be used. In addition, it is also beneficial if viscosity-influencing substances or substance mixtures be used in the liquid. This allows the necessary total amount of liquid based on the amount be further reduced to the ground material to be crushed. The Viscosity-influencing substances, in an advantageous manner increase the viscosity of the liquid, usually cause the individual particles of the to be comminuted grinding material by stronger adhesion forces a more stable layer of good bed while reducing the form necessary amount of liquid. In the viscosity-influencing Substances may be binders, pulp, cellulose, vegetable flours, organic and / or inorganic salts or clay or clay minerals added to the liquid become.

In Preferably, the roller is 0.1% to 2%, preferably from 0.2% to 1% and more preferably from 0.3% to 0.5% liquid sprayed on per ton of regrind. Here is the quantity ratio expressed in liters per ton of grinding stock to be comminuted.

Around It has gotten to reduce the amount of fluid further proved to be advantageous when an arrangement for controlling the amount of liquid application is used, this arrangement with increasing Freilage the roll shell more liquid at the same roller rotation speed sprayed on the roller. This will create a loop created at the collapse of Gutbettbildung or wear protection layer formation more liquid sprayed on the roller and at sufficient training of Gutbettts is the amount of liquid reduced accordingly. This will only be liquid applied to the roller when a collapse of the manure bed or the wear protection layer requires this, so that to dispense with an excess of water application to the roller can, what a saving of liquid means.

Next the arrangement for regulating the amount of liquid application It is also possible to have a model for real-time calculation to use the order quantity, taking the model as input parameter the Mahlguteintrags performance and Mahlgutfeuchte and with Help of this model becomes a liquid application performance determined and set automatically. The use of a model for the real-time calculation of the order quantity has the advantage that the Freilage the roll shell does not need to be determined, but it can the grinding material input and the regrind moisture which are analytically easier to determine than the freeing of the roll mantle, which is complicated by computerized Control circuits must be determined.

to Implementation of the above method is a roll mill proposed, whose roller shells to form a Autogenous wear protection embedded hard body have, in addition to a first material for the millbase provided at least a second material loading is which liquid and / or a moistened regrind fraction and / or a Mahlgutfraktion with respect to the material to be ground applied composition to the rollers. In the simplest case, water is sprayed onto the roller mill, so as to keep the autogenous wear protection layer moist.

The second material application can be a simple spray head be that sprays liquid onto the rollers, so that from the liquid and the dry to crush Ground material formed an autogenous wear protection layer or it is possible that the second material application a previously moistened fraction to be comminuted millbase the rollers hangs up, the second material loading continues removed from the nip is as the material for the grinding stock to be comminuted.

In Advantageously, a spray head for the application of liquid on the rolls at an angle of 35 ° to 55 ° is preferred arranged at about 45 ° to the vertical of the roller, this angle being from the vertical outwards measured on the position of the nip.

Here By getting an optimal order of liquid on the Roller reaches, so that the roller mill with the least possible amount to form an autogenous wear protection layer can be operated.

Provided is provided to regulate the second material exposure, has it proved to be advantageous when the roll mill has an arrangement for regulating the power of the second material application, this arrangement for regulating the performance of the freeing of the Roll surface and from this the optimal amount of liquid application can determine or it is possible from the regrind the roller mill and the measured humidity of the crushing regrind an order amount of liquid or to determine already wetted regrind.

The The invention will be explained in more detail with reference to the following figures:

It demonstrate

table 1: The particle size distribution of the test material

table 2: Summary of experimental conditions and results

1 : Experimental setup,

2 : A sketch of the present invention Gutbettwalzenmühle mit- spraying

3 : Roll surface after trial E1

4 : Roll surface after trial E2

5 : Roll surface after trial E3

Table 1 shows the particle size distribution of an iron ore from Mauritania originating from the EI Aouj Mine. Here, the "material feed" column represents the cumulative material size distribution of the input material into the commodity bed mill in mass percent, the column "roll center" represents the cumulative material size distribution in the roll center, and the column "roll end" represents the cumulative material size distribution at the lateral ends of the roll. This ore presented was, according to Ver in Table 2, three tests were conducted to examine the influence of the amount of moisture on the formation of an autogenous wear protection layer when spraying water onto a roll mill. Table 1: cumulative mass%, screen passage Screen mesh size, mm material supply roll center roll end Total 31.5 100.00 100.00 100.00 100.00 22.4 93.26 100.00 100.00 100.00 16.0 80.54 98.79 88.27 96.95 11.2 67.48 94.95 73.12 91.13 8:00 54.25 88.74 56.65 83.13 5.60 43.49 83.10 44.63 76.37 2.80 26.46 69.40 29.12 62.36 1:00 11:32 49.32 14:51 43.23 0500 8.24 38.23 9.65 33.23 0315 6.23 30.96 6.87 26.75 0200 4:38 23:38 4:50 7.20 0125 2.85 16.60 2.72 14:17

• (1) Schätzung auf Basis von Fotografien
• (2) visuell-haptische Prüfung
• (3) max. Schichtdicke: 5 mm, limitiert durch Hohe der Hartkörper

From Table 2 it can be seen that in the first attempt, the dry ore was milled without spraying the roller. In Experiment E2, the dry ore was milled with a water feed rate of 0.75 liters per minute, which corresponds to a humidification of 0.13 liters of water per square meter of roll surface in the above-described roll mill, and the E3 attempt was with a spray rate of 2.0 liters per minute, which corresponds to an output of 0.36 liters of water per square meter roll surface under the conditions specified. Table 2: experimental condition E1 E2 E3 Humidification capacity per roller, l / min 0 0.75 2.00 Rotation frequency of the rolls, UPM 9.1 9.1 9.1 Water coating, l / m ² 0 0.13 0.36 Nitrogen pressure, bar 66 66 67 specific pressure, N / mm ² 4.25 4.25 4.29 Throughput, t / h 28.4 28.6 27.2 specific throughput, Ts / hm ³ 376 378 366 Energy requirement, net, kW 33.4 33.3 34.1 specific energy kWh / t 1.18 1.16 1.25 Roller cover,% ⁽¹⁾ 36 65 90 Good bed, visual and haptic examination ⁽²⁾ soft, brittle, lots of empty surfaces relatively firm, a bit brittle stuck, a little too wet average good bed layer thickness ⁽³⁾ 1.2 2.5 4.0

• (1) Estimation based on photographs
• (2) visual-haptic examination
• (3) max. Layer thickness: 5 mm, limited by height of the hard body

In 1 is therefore shown as water on the experimental roller mill 2 . 3 was sprayed on. This was a simple nozzle body 4 used the water at an angle of approximately 40 to 45 degrees to the axle vertical on the roller 2 . 3 sprayed on. The roller itself has a diameter of 0.8 meters and a width of 0.25 meters. The operating capacity of this roller mill is about 75 tons per hour. For the spraying experiments, an arrangement of two spray heads was arranged on both rollers at an angle of about 40 degrees with the vertical axis, said spray heads could give a maximum of about 2.5 liters per minute of water to the roller. For example, water was sprayed on every roller up to a maximum of 5 liters per minute during operation. To carry out the experiment, a relatively coarse nozzle was used so that the water was not finely dispersed. The finer the water is dispersed, the more efficient the effect of moistening, however, it is considered that a fine nozzle clogs more easily under the harsh conditions prevailing in the high bed roller mill than a coarse nozzle. Optimal atomization must be stopped by experimentation.

In 2 is the experimental setup off 1 shown in perspective view. It can be clearly seen as a nozzle body 4 , Hereby juxtaposed spray nozzles liquid on the roller 2 sprayed.

The result of experiment E1 is in 3 shown. It adheres only a little to comminuted regrind on the roll surface. The material is brittle and breaks out very easily. On most of the surface no or only a very thin wear protection layer has built up, which is removable with a soft brush from the surface of the roller.

Under the conditions of experiment E2, a significantly better adhesion of the wear protection layer to the roll surface is achieved. Of the 4 It can be seen that more material accumulates on the roll surface and that the wear protection layer thickens. Especially at the edge of the rollers more material has embedded. Nevertheless, the moistening performance is not sufficient, because on some parts of the roller surface no wear protection layer has yet built up. Under these conditions, the wear protection layer had already solidified and the stored material could be removed only with the aid of a steel brush from the surface of the roller.

The result of experiment E3 is a clearly complete adhesion of the wear protection layer on the surface of the rolls. In 5 is shown that the rollers are almost completely covered with the autogenous coating, and that the layer thickness has reached a maximum height, so that the embedded hard body have a same height as the intermediate wear protection layer. The embedded between the hard bodies material was difficult to remove under the experimental conditions E3, with a steel brush or a screwdriver had to be used to remove the anti-wear layer.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 4036040 A1 [0002]

Claims (16)

Process for continuous comminution brittle ground material, in particular ore, in which the to be crushed Ground material through the gap of two counter-rotating Rolling is performed, the rollers to form a Autogenous wear protection embedded hard body characterized by the use of a moistened Good bed on the roll surface. Method according to claim 1, characterized by Loading the rollers with wetted regrind, the to be comminuted regrind in a larger and a smaller fraction is divided and the smaller fraction moistened and the larger fraction open unburned becomes. Method according to claim 2, characterized by a different location of wetter and drier Fraction. Method according to one of claims 1 to 3, characterized by the use of a roller wear protection layer having a composition other than the millbase, wherein the good bed with Clay, clay, fine sand or other materials that have a tendency to lump have enriched. Method according to claim 1, characterized by Spraying liquid onto the roll surface the rollers. Method according to claim 5, characterized by Use of water, seawater, sewage, agricultural Waste, industrial wastewater and / or industrial Liquid waste as a liquid. Method according to one of claims 5 to 6, characterized by the use of viscosity-influencing Substances or mixtures of substances in the liquid. Method according to claim 7, characterized by Use of binders, pulps, cellulose, vegetable flour, organic and / or inorganic salts as viscosity-enhancing Substance or viscosity-influencing substance mixture. Method according to one of claims 5 to 8, characterized by the spraying of 0.1% to 2%, preferably from 0.2% to 1%, more preferably from 0.3% to 0.5% liquid per ton of regrind, with the ratio in liters per ton is specified. Method according to one of claims 5 to 9, characterized by the use of a control arrangement the liquid application amount, with increasing free-standing the roll shell more liquid at the same roller rotation speed the roller is sprayed on. Method according to one of claims 5 to 10, characterized by the use of a model for real-time calculation the order quantity of the liquid as input parameter the grinding material input power and the grinding material moisture are received and with Help the model determines a liquid application performance and is set automatically. Roll mill, whose roll shells for the formation of an autogenous wear protection embedded hard body have, characterized in that in addition to a first material loading for the regrind, at least a second application of material is arranged, which liquid and / or a moistened Grindstock fraction and / or a regrind fraction with opposite the regrind modified composition on the rollers applying. Roll mill according to claim 12, characterized in that that at least one spray head on each liquid one roller sprays each. Roll mill according to claim 13, characterized that the at least one spray head at an angle (α) is arranged from 35 ° to 55 °, by the by the roll axis drawn vertical plane opposite to the rolling direction is measured. Roller mill according to claim 12, that in addition the Mahlguteintragsort an arrangement is provided which is another Grist grain fraction is applied to the roller. Roll mill according to one of the claims 12 to 15, characterized in that an arrangement for regulation the power of the second material application is provided.