LU103193B1 - Component grinding of cement components - Google Patents

Abstract

The present invention relates to a process for producing a cement from at least two components, characterized in that at least two of the components are ground separately.

Description

thyssenkrupp Polysius GmbH 230120P00LU thyssenkrupp AG 08/30/2023 LU103193 1/7

Component grinding of cement components

The invention relates to a method for the efficient grinding of various

Components for a cement.

In cement, the substitution rate is increasing.

The proportion of fired clinker has been reduced. Common substitutes today include unfired limestone, calcined clays, pozzolans, granulated blast furnace slag, steel slag,

Fly ash, and the like. To achieve the specified strength classes, the cements typically have to be ground more finely. This leads to higher energy consumption during grinding. In addition, the different components have different grindabilities, so the easier-to-grind components are ground much finer than necessary.

This further increases the energy requirement for grinding.

Another point to consider is the vibration level of the mill. This can be

Moisture, which is, however, detrimental to the product, must be counteracted. It is therefore necessary to maintain the required fineness with the least possible water addition and a sufficiently low vibration level in the mill.

US 2013/0040257 A1 discloses a method and a device for

cement production known.

EP 3 326 720 B1 describes a process for the processing of multiphase mineral

raw materials known.

A process for producing cement is known from EP 2 906 510 B1.

EP 2 980 036 B1 discloses a process for grinding cement clinker.

The object of the invention is to provide a method for grinding in which all

Components are ground to the required fineness in an energy-efficient manner.

thyssenkrupp Polysius GmbH 230120P00LU thyssenkrupp AG 08/30/2023 LU103193 217

This object is achieved by the method with the features specified in claim 1

Features. Advantageous further developments emerge from the subclaims, the following description and the drawings.

The process according to the invention serves to produce a cement from at least two components. For example, the cement can be a cement classified as CEM I. Clinker is preferably selected as the first component. Clinker, burnt lime, creates an alkaline environment when mixed with water during setting. Gypsum, for example, can be selected as the second component, which is used as a sulfate carrier to adjust the setting behavior. At least two of the components are ground separately. This allows the first component and the second component

Each individually can be optimally ground depending on the grindability and the

The fineness required for the final product can be achieved. This allows, for example, the more difficult-to-grind component to be ground more finely without the easier-to-grind component being ground unnecessarily finely, thus consuming unnecessary energy.

In a further embodiment of the invention, the first component is clinker and the second component is selected from the list comprising gypsum, unfired

Limestone, calcined clays, pozzolans, granulated blast furnace slag, steel slag, fly ash, old concrete,

Old cement brick. The clinker substitutes have the advantage that the

Clinker production avoids very high carbon dioxide emissions (from the lime), thus making it easy to prevent emissions. In addition, some substances, such as pozzolans, can impart advantageous properties to the concrete made from cement, for example, in terms of water resistance.

In a further embodiment of the invention, the separate grinding takes place one after the other in the same device. Especially with a vertical roller mill, it is particularly easy to change the grinding material, so that a quick change simplifies a separate process in just one device, which in turn reduces the

Investment reduced.

thyssenkrupp Polysius GmbH 230120P00LU thyssenkrupp AG 08/30/2023 LU103193 3/7

In a further embodiment of the invention, the second component is ground finer than the first component. Clinker as the first component has a high

reactivity, practically all clinker substitutes that can be chosen as the second component have a lower reactivity, so that a finer

Grinding is necessary. Therefore, the cement is normally ground as a mixture, which in turn results in the comparatively easy-to-grind clinker being ground much more finely, making it significantly finer than the third component. By separating the clinker and grinding it coarser to the required fineness, grinding energy is saved.

In a further embodiment of the invention, the first component is applied to a

Fineness of at least 5250 cm?/g according to Blaine. A

Fineness not exceeding 6000 cm?/g, preferably not exceeding 5750 cm?/g, particularly preferably not exceeding 5500 cm?/g. The fineness of at least 5250 cm?/g according to

Blaine for clinker corresponds to a residue of less than 8% of the particles on a 25 um sieve.

In a further embodiment of the invention, the second component is applied to a

Ground to a Blaine fineness of at least 6000 cm?/g. A Blaine fineness of at least 6000 cm?/g corresponds to a residue of less than 1% of the particles on a 32 µm sieve for granulated blast furnace slag.

In a further embodiment of the invention, clinker and gypsum are ground together.

In a further embodiment of the invention, a fineness of at least 5250 cm?/g up to 6750 cm?/g according to Blaine and a residue of less than 8 wt.%

Residue on the 25 um sieve achieved during grinding.

In a further embodiment of the invention, at least one third component is used to produce the cement. The third component is different from the second component and is selected from the list comprising gypsum, unburned limestone, calcined clays, pozzolans, granulated blast furnace slag, steel slag,

thyssenkrupp Polysius GmbH 230120P00LU thyssenkrupp AG August 30, 2023 LU103193 4/7

Fly ash, old concrete, old cement block. At least two of the components are ground together and at least two of the components are ground separately. For example, the clinker can be ground together with the gypsum (as the third component) and the second component, for example granulated blast furnace slag, separately, or the gypsum and the second component, for example granulated blast furnace slag, are ground together and the clinker separately, or the clinker and the gypsum are ground together and the second component, for example granulated blast furnace slag, and the gypsum are also ground together separately. Thus, there is no joint

Mixing and grinding of all components takes place in a single grinding step, as is currently the norm. This allows the different grindability of the clinker and the second component to be specifically taken into account.

In particular, the clinker substitutes selected as the second component typically require a lower fineness than the clinker. At the same time, they exhibit lower grindability, so that when milled together, the more easily grindable material is overground, resulting in excessive energy consumption.

In a further embodiment of the invention, size-selective separation takes place after milling. The coarse fraction is returned to the mill, the

Fine fraction is extracted as a product. This opens the possibility of

Use also of mills that cannot immediately achieve the necessary fineness for the entire ground material.

For a vertical roller mill, a classifier has proven particularly suitable for size-selective separation, as the material to be ground is carried out of the vertical roller mill in a gas stream and can thus be fed directly to a classifier. The classifier preferably separates only the coarse fraction. The fine fraction is then separated from the gas stream, for example, in a dust filter.

In a further embodiment of the invention, a

Vertical roller mill is selected. The vertical roller mill achieves the required

Finenesses in an energy-efficient manner with a high throughput and can also be switched between different grinding materials comparatively quickly and easily.

In a further embodiment of the invention, a combination of a high-pressure roller mill and a ball mill is used for grinding. Preferably, a size-selective separation is used, producing a coarse fraction, a medium fraction, and a fine fraction. For example, this can be a classifier.

The material input stream is fed to the size-selective separation device and the coarse fraction is fed to the high-pressure roller mill.

The material crushed by the high-pressure roller mill is returned to the material input stream. The middle fraction is removed from the size-selective separation device of the

The material ground in the ball mill is then

Material is fed back into the size-selective separation device. The

The fine fraction is either removed as product or passed through a second size-selective separation device, whereby the second coarse fraction of the

ball mill. This makes it easy to achieve higher finenesses.

The method according to the invention is explained in more detail below with reference to embodiments shown in the drawings.

Fig. 1 first example

Fig. 2 second example

Fig. 1 shows a first exemplary device for carrying out the method according to the invention. Via the material feed 10, a

Clinker gypsum or a mixture of activated clay and gypsum is fed to a vertical roller mill 21. Gas is also fed to the vertical roller mill via a gas supply 12.

As a result, the light, ground material is discharged with the gas stream and fed to a size-selective separating device 30, which is also housed in a housing with the

vertical roller mill 21. There, the separation takes place into a

Coarse fraction 32, which is fed back to the vertical roller mill and into a

Fine fraction, which is fed into a dust separator 40 thyssenkrupp Polysius GmbH 230120P00LU thyssenkrupp AG 30.08.2023 LU103193 6/7 to separate solids and gas. The gas is discharged via gas outlet 44 and can theoretically be

Gas inlet 12 is returned. The finished product is removed via product outlet 42. Through separate grinding, the cement can be produced with all components at the optimal fineness and no component being ground too finely, thus optimizing the energy requirement for grinding.

Fig. 2 shows a second exemplary device for carrying out the method according to the invention. A clinker

Gypsum or a mixture of activated clay and gypsum of a size-selective

separating device 34, which divides the material into a fine fraction 31, a

medium fraction 33 and a coarse fraction 32. The coarse fraction 32 is subjected to a high-pressure

Roller mill 22 and crushed there. The ground material 25 is fed to the material feed 10 and thus to the renewed size-selective separation. The middle fraction 33 is fed to a ball mill 23 and the ground material 25 from the ball mill 23 is fed back to the size-selective separation device 34. The fine fraction is fed to a second size-selective separation device 35, the second coarse fraction 36 from the second size-selective separation device 35 is added to the middle fraction 33 and the

Ball mill 23. The fine fraction of the second size-selective

Separator 35 is fed to a dust separator 40, the gas is

Gas outlet 44 and the product is removed via product outlet 42.

Reference numerals 10 Material feed 12 Gas feed 21 Vertical roller mill 22 High-pressure roller mill 23 Ball mill 25 Ground material size-selective separation device 30 31 Fine fraction 32 Coarse fraction 33 Medium fraction 34 Size-selective separation device thyssenkrupp Polysius GmbH 230120P00LU thyssenkrupp AG 30.08.2023 LU103193 717 35 Second size-selective separation device 36 Second coarse fraction 40 Dust separator 42 Product outlet 44 Gas outlet

Claims (12)

thyssenkrupp Polysius GmbH 230120P00LU thyssenkrupp AG 30.08.2023 LU103193 1/2 Patent claims 1. A process for producing a cement from at least three components, characterized in that at least two of the components are ground together and at least two of the components are ground separately. 2. Process according to claim 1, characterized in that the first component is clinker, the second component being selected from the list comprising gypsum, unburnt limestone, calcined clays, pozzolans, granulated blast furnace slag, steel slag, fly ash, old concrete, old cement brick. 3. Method according to one of the preceding claims, characterized in that the separate grinding takes place successively in the same device. 4. Process according to one of the preceding claims, characterized in that the second component is ground more finely than the first component. 5. A process according to any one of the preceding claims, characterized in that the first component is ground to a Blaine fineness of at least 5250 cm?/g. 6. A process according to any one of the preceding claims, characterized in that the second component is ground to a Blaine fineness of at least 6000 cm?/g. 7. A process according to any one of the preceding claims, characterized in that clinker and gypsum are ground together. 8. A process according to any one of the preceding claims, characterized in that a fineness of at least 5250 cm?/g up to 6750 cm?/g according to Blaine and a residue of less than 8 wt.% residue on the 25 µm sieve is achieved during grinding. 9. Process according to one of the preceding claims, characterized in that at least one third component is used to produce the cement, wherein the third component is different from the second component and is selected from the list comprising gypsum, unburnt limestone, calcined clays, pozzolans, granulated blast furnace slag, steel slag, fly ash, old concrete, old cement block, wherein at least two of the components are ground together and at least two of the components are ground separately. 10. Method according to one of the preceding claims, characterized in that after grinding, a size-selective separation takes place, the coarse fraction (32) being returned to the mill, the fine fraction (31) being removed as product. 11. Method according to one of the preceding claims, characterized in that a vertical roller mill (21) is selected for grinding. 12. Method according to one of claims 1 to 10, characterized in that a combination of a material bed roller mill (22) and a ball mill (23) is used for grinding.