LU103013B1 - Ready-to-use Portland pozzolana cement - Google Patents

Abstract

The present invention relates to a method for producing a binder, the method comprising the following steps: a) thermally activating a clay at elevated temperature to form an activated clay, b) mixing the activated clay at elevated temperature with a reactive agent such that the reactive agent is reacted by the heat of the activated clay, the reactive agent being reacted by the thermal energy of the activated clay, the reactive agent being converted into a lye-forming material.

Description

thyssenkrupp Industrial Solutions AG 221308P00LU thyssenkrupp AG LU103013 1/9

Ready-to-use Portland pozzolana cement

The invention relates to a process for producing a ready-to-use

Portland pozzolana cement.

Calcined clay or naturally tempered pozzolana, for example, has been suggested as a cement substitute or SCM. Calcined clay is a suitable, naturally occurring clay that can be thermally tempered at a suitable temperature.

temperature so that it acquires pozzolanic properties. Clays suitable for this purpose generally contain clay minerals in the form of 1-layer and/or 2-

Layers of phyllosilicates, such as kaolinite, illite or montmorillonite. In addition, these clays can contain accompanying minerals such as quartz, feldspar, calcite,

Dolomite, but also metal oxides and hydroxides or especially iron hydroxides.

Naturally occurring clays are often rich in iron and/or contain other colouring metals, so that during conventional calcination, for example, a reddish and/or brownish discolouration of the product occurs. Although this colouring is not relevant for the strength and other building material properties, it is

Plant operators and building material customers classify it as undesirable. According to current

The acceptance of a building material by end users depends on the status, i.e. the

Market potential of calcined clays and thus the potential for possible CO>»-

Savings depend significantly on their color.

In addition, the activated clays (on their own) cannot be used as binding agents, i.e. they require another component that creates a basic environment when mixed with water and thus causes the clay to set. A more artificial pozzolan must therefore be mixed with at least one suitable component that acts as a stimulant.

For example, in the cement industry, activated clays are used as a substitute to reduce the clinker factor. This can also reduce CO2 emissions, since, unlike lime, no CO2 is released from the clays during thermal treatment. These clays are activated at a temperature of 800 °C, for example. An important point for the finished product is that the customer usually expects a white or at most light gray product, but the clays used are often

Iron or manganese. In an oxidizing mode of clay activation, these elements are oxidized within their corresponding minerals at the required temperatures and then have an intense reddish to brownish color. Therefore, these activated clays are either produced under a reducing atmosphere or after activation at correspondingly high

Temperatures in a reducing environment reduce and thereby decolorize.

The product must then be cooled at least to such an extent that extensive renewed oxidation by cooling with ambient air, with a corresponding color change towards red/brown, no longer occurs (at least not to an optically disturbing extent).

The calcination of fine-grained mineral solids, such as clay, is conventionally carried out in rotary kilns, multi-storey furnaces, fluidized bed furnaces or

Entrained flow ovens. This ensures that a required minimum temperature is maintained for the residence time necessary for the treatment in this process.

For example, US 4,948,362 A describes a process for calcining clay in which

Kaolin clay to increase the whiteness and minimize abrasiveness in a

The clay powder is treated in a multi-storey oven using a hot calcining gas. In an electrostatic filter, the calcined clay powder is separated from the exhaust gas of the

Calcination furnace and further processed to obtain the desired product.

Currently, two methods of cooling are used. In the first

In this method, water is used for cooling and water vapor is produced with a

Temperature around the boiling point and under normal pressure. In a second method, the product is cooled in a screw with cooling water, producing warm water at about 60 °C. Both are energy levels in which thermal energy in a

The system network cannot be used or can only be used to a very limited extent.

thyssenkrupp Industrial Solutions AG 221308P00LU thyssenkrupp AG LU103013 3/9

WO 2015/104466 A1 describes the production of cement with a

Heat treatment and subsequent mixing cooling with pozzolanic

substances known.

EP 3218 320 B1 discloses a process for the heat treatment of natural clays and/or zeolites, wherein the clay and/or zeolite is calcined in the calcination zone in an entrained flow calciner or a fluidized bed in a temperature range of 350 to 1050 °C under reducing conditions, wherein during the

Calcination under reducing conditions results in a reduction of reddish colored trivalent iron to divalent iron.

US 9 458 059 B2 discloses a process for producing synthetic pozzolans with desired color characteristics by cooling under reducing conditions.

DE 102011014498 B4 describes a method for producing a

Clinker substitute for use in cement production, whereby a thermal treatment of the clay under reducing conditions at a

Temperature of 600 to 1,000 °C and intermediate cooling of the reduction product under exclusion of oxygen to a temperature < 300 °C.

From DE 10 2008 020 600 B4 a process for the heat treatment of fine-grained mineral solids is known, wherein the solids are passed through a flash reactor in which they are brought into contact with hot gases at a temperature of 450 to 1500 °C and a residence time of between 0.5 and 20 seconds, and wherein the solids are then passed through a residence time reactor at a temperature of 500 to 890 °C, from which they are withdrawn after a residence time of 1 to 600 minutes.

From US 2012 / 160 135 A1 a process is known for producing synthetic pozzolans with desired color properties by cooling under a reducing atmosphere.

thyssenkrupp Industrial Solutions AG 221308P00LU thyssenkrupp AG LU103013 4/9

EP 3615 489 A2 describes a process for producing grey synthetic

Pozzolans with an initial rapid cooling below 600 °C are known.

From WO 2015/039 198 A1 a process for producing a preparation for the partial substitution of Portland cement with a grey colour is known.

DE 10 2020 211 750 A1 describes a method and a device for optimal

Heat recovery during cooling of color-optimized activated clays is known.

EP 3070 064 B1 describes a process for producing a low-carbon

Clinkers known.

The object of the invention is to provide a process by which a binder with an activated clay can be easily produced.

This object is achieved by methods having 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 binder. The

The method comprises the following steps: a) Thermally activating a clay at elevated temperature to form an activated

Clay, b) mixing the activated clay at elevated temperature with a reactive agent so that the reactive agent is reacted by the heat of the activated clay,

It is essential that the reactive agent is activated by the thermal energy of the

A chemical conversion takes place, the energy required for this is extracted from the activated clay and this is cooled quickly and efficiently. The reactive agent is thereby converted into a lye-forming material. A lye-forming material in the sense of the invention is a

Material which creates an alkaline medium under the influence of water.

An example of this would be lime, CaCOs. Under the influence of heat, CaO forms, which would be a lye-forming material in the sense of the invention. When water is added, Ca(OH) is formed, and thus an alkaline medium. This alkaline medium is required to set the activated clay. This creates a complete binding agent that can be used directly. Another example of a reactive agent is

Old cement brick, which is obtained from old concrete during processing, but which itself must first be reactivated.

Optionally, further treatment can be carried out afterwards, for example in

Grinding can be done. It can also be useful to add other ingredients optionally.

The process according to the invention has two advantages. Firstly, the waste heat from the

Activation of the clay is used to carry out a further process, the thermal treatment of the reactive agent to form the lye-forming material. On the other hand, this cools the activated clay very quickly and efficiently.

In a further embodiment of the invention, color optimization takes place in a reducing atmosphere between step a) and step b). Many clays contain color-giving components, for example and in particular fur. If these are reduced, the product becomes more gray, which improves the acceptance of the product.

However, it is crucial that the reduced activated clay is then cooled without further oxidation taking place. There are a number of strategies for this, mostly cooling under protective gas or very rapid cooling. The process according to the invention is synergistic here. By mixing the activated clay with a reactive agent, not only is a simple cooling achieved, but the chemical reaction in the reactive agent also extracts more energy from the activated clay and more quickly, so that the color can be maintained more easily after reduction. There is also another effect. CO2 is released from lime, from

Old cement brick water. These gases are created in the immediate vicinity of the heat-emitting activated clay and thus contribute to a local atmosphere that is at least less oxygen-rich.

In a further embodiment of the invention, the amount of phosphorus added in step b) is

Amount of the reactive agent between 10 wt.% and 250 wt.%, preferably between thyssenkrupp Industrial Solutions AG 221308P00LU thyssenkrupp AG LU103013 6/9 15 wt.% and 150 wt.%, more preferably between 20 wt.% and 50 wt.%, particularly preferably between 23 wt.% and 26 wt.%, of the mass of the activated

Tones. Here, the mass of the activated tone is considered as 100%. The

The total amount depends on the amount added. In this

Mixing ratios provide efficient cooling on the one hand, and a product that can be used immediately with optimal binding properties on the other.

In a further embodiment of the invention, the binder is cooled after step b). For example, the binder can be a mixture of activated clay and reactive agent/lye-forming material and can be cooled to a temperature of 300 °C in step b). The binder is then cooled in a direct current entrainment system.

Heat exchangers with separation cyclones (if necessary in a cascade of such) further cool it, in particular to below 100°C, so that it can be stored, filled or transported away.

In a further embodiment of the invention, the reactive agent is selected from the group comprising lime, limestone, dolomite, old cement stone.

Lime, limestone or dolomite are particularly preferred if the clay is activated in step a) at a temperature between 1200 °C and 950 °C.

Old cement brick is particularly preferred if the clay in step a) has a

Temperature between 950 °C and 700 °C is activated.

In a further embodiment of the invention, the mixing in step b) takes place in a mixer. For example, the mixer is equipped with a

Mixing tool, for example a screw mixer. Through active and intimate mixing, . Alternatively, the mixer is a static

Mixer, i.e. a mixer without moving parts, which is advantageous at high temperatures. A mixer that allows the solids to be mixed thoroughly and has as little gas volume as possible is preferred. This means that as little oxygen as possible is present, which could cause the activated clay to change color.

thyssenkrupp Industrial Solutions AG 221308P00LU thyssenkrupp AG LU103013 7/9

The method according to the invention is explained in more detail below using an embodiment shown in the drawings.

Fig. 1 first exemplary embodiment

Fig. 2 second exemplary embodiment

Fig. 3 third exemplary embodiment

Fig. 4 fourth exemplary embodiment

Fig. 1 shows a first exemplary embodiment of a system for carrying out the method according to the invention. Clay is fed into a

Preparation device 10, in which the clay is dried and crushed, for example. From there, the clay is transferred to a preheater 20. The preheater 20 can be designed, for example, as a cascade of direct current heat exchangers with a separating cyclone. From there, the clay is transferred to the calciner 30 for thermal activation, which is brought to the temperature required for activation by a combustion chamber 40. The activated clay is then transferred to a

reduction device 50 for color optimization.

For this purpose, hydrogen, hydrocarbon-containing gases, carbon monoxide, synthesis gas or mixtures of these, in particular with nitrogen, exhaust air from the process and/or carbon dioxide, are fed to the reducing agent supply 140. The activated and color-optimized clay is transferred to a mixer 60 and there mixed with a reactive agent fed via the reactive agent supply 110, for example

Old cement brick, intimately mixed. Not only by mixing with a preferably much cooler material, but especially by implementing the

Reactive agent in a lye-forming material, heat is quickly removed from the clay and thus the clay is quickly cooled, so that re-oxidation of the color-optimized

Tones is prevented. In addition, a mixer 60 is particularly suitable for intimately mixing two solids with the lowest possible gas content above the solid. The resulting

The product is cooled further in a material cooler 70 and discharged via the product output 120. In the example shown, air in particular is introduced into the material cooler 70 via the gas supply 130 and heated there. The heated air is then transferred to the preparation device 10, where the clay is dried by the heat introduced with the air. The air leaves the preparation device 10 via the preparation exhaust air 160. The exhaust gas emerging from the reduction device 50, which may still contain unburned components, is fed to the calciner 30 and is completely burned there. The gas leaves the calciner 30 and is transferred to the preheater 20, where it preheats the clay and is itself cooled before being discharged via the preheater exhaust air 150.

Fig. 2 shows a second exemplary embodiment, which differs from the first exemplary embodiment in that the mixer 60 is dispensed with and instead the reactive agent is fed directly into the material cooler 70 via the reactive agent feed 110. The material cooler 70 is preferably designed as a

Cascade of co-current heat exchangers with separation cyclone, whereby the colour-optimised activated clay and the reactive agent are mixed together in the first

DC heat exchanger of the cascade.

In Fig. 3, a third exemplary embodiment is shown, which differs from the first exemplary embodiment in that a portion of the air heated in the material cooler 70 is additionally fed into the reduction device 50. Furthermore, at least a portion of the gases from the preheater exhaust air 150 and the preparation exhaust air 160 of the

Combustion chamber 40.

Fig. 4 shows a fourth exemplary embodiment which differs from the second exemplary embodiment in that a portion of the air heated in the material cooler 70 and at least a portion of the gases from the preheater exhaust air 150 and the preparation exhaust air 160 are additionally supplied to the combustion chamber 40.

Reference numerals 10 Preparation device 20 Preheater 30 Calciner

Combustion chamber

Reduction device 60 Mixer thyssenkrupp Industrial Solutions AG 221308P00LU thyssenkrupp AG LU103013 9/9 70 Material cooler 100 Clay feed 110 Reactive agent feed 120 Product output 130 Gas feed 140 Reducing agent feed 150 Preheater exhaust air 160 Preparation exhaust air

Claims (6)

thyssenkrupp Industrial Solutions AG 221308P00LU thyssenkrupp AG LU103013 1/1 Patent claims 1. A process for producing a binder, the process comprising the following steps: a) thermally activating a clay at an elevated temperature to form an activated clay, b) mixing the activated clay at an elevated temperature with a reactive agent such that the reactive agent is reacted by the heat of the activated clay, the reactive agent being reacted by the thermal energy of the activated clay, the reactive agent being converted into a lye-forming material. 2. Process according to claim 1, characterized in that between step a) and step b) a colour optimization takes place in a reducing atmosphere. 3. Process according to one of the preceding claims, characterized in that the amount of the reactive agent added in step b) is between 10% by weight and 250% by weight, preferably between 15% by weight and 150% by weight, more preferably between 20% by weight and 50% by weight, particularly preferably between 23% by weight and 26% by weight, of the mass of the activated clay. 4. Method according to one of the preceding claims, characterized in that after step b) the binder is cooled. 5. Process according to one of the preceding claims, characterized in that the reactive agent is selected from the group comprising lime, limestone, dolomite, old cement stone. 6. Method according to one of the preceding claims, characterized in that the mixing in step b) takes place in a mixer (60).