FI126846B - Process for the preparation of combination particles - Google Patents

Description

METHOD FOR PREPARING COMPOUND ARTICLES

Background of the Invention

Field of the Invention

The present invention relates to a process for the preparation of composite particles having a kaolin portion and a limestone portion, which are joined together by activating the surfaces of the particles of the separate portions, for example by calcination.

Description of the Prior Art

Concrete is the most common building material in the world. It is composed of aggregate and cement, which is generally made up of Portland cement. With the growth of the construction industry, more and more cement is needed. In this case, attempts have been made to replace it, at least in part, with other substances, or to add fillers.

For example, U.S. Patent No. 4,588,443 describes a method for producing concrete using particles of various sizes mixed with a surfactant dispersant.

Cement raw materials include calcium carbonate, iron oxide, aluminum and silica, which react to form various minerals such as silicates and aluminates. Cement also contains small amounts of other materials such as sodium and calcium oxides. When the cement and other concrete components come into contact with water, these materials will be hydrated, causing the concrete to harden. However, the hydration of the various components occurs at different stages and speeds and is, for the most part, difficult to control. In practice, Portland cement activation, that is, hydration, will never be complete. This leaves water in the concrete even after the initial cure. The amount of water is often reduced to improve the strength and durability of the concrete. This is conventionally done, for example, with pliers. However, the increase in these numbers contributes to the quality of the concrete.

The challenge in replacing Portland cement is, among other things, to form a cement that is economical but still functions as an effective and inexpensive binder.

One alternative binder used is metakaolin, which is conventionally added to the concrete as a powder. Due to its pozzolanicity, metakaolin reacts with excess calcium hydroxide in the concrete to compact the concrete by filling voids. It also protects the concrete structure from environmental influences such as steel corrosion. Thus, the use of metakaolin can achieve stronger, more durable concrete, improve its workability and reduce shrinkage, even without the use of separate additives. Metakaolin syntheses have also been used.

Metakaolin has been used to replace about 1/3 of Portland cement in concrete products. The magnitude of this proportion is dependent on the amount of the above-mentioned excess calcium hydroxide produced by Portland cement and the time of its formation.

As another alternative to conventional Portland cement, various composite particles have been formed. One such is described in WO 2010/130511 A1, where the combination described consists of calcium carbonate and metakaolin. This is prepared by mixing kaolin or other clay with finely ground calcium carbonate (CaCCh) and heat treating this combination at 750 ° C for about 20 minutes. WO 2010/037903, in turn, describes a structured binder consisting of metakaolin sintered on the surface of which calcium carbonate and plasticizing organic polymers and Portland cement are precipitated. This product is prepared by calcining kaolin before being contacted with other ingredients. Metakaolin sinter (spherical) is brittle and bulky. When calcined, these balls disintegrate to form loose kaolin sheets. When using metakaolin as such as part of a cement, activation requires high temperatures and bases stronger than Ca (OH) 2 (e.g. NaOH). This has been the main obstacle to the spread of the use of these types of cements.

Geopolymers have also been formed to replace some of the Portland cement. In these, the activation is not dependent on the formation of hydrates, nor on high temperatures, and their production does not result in the same carbon dioxide emissions as in the manufacture of Portland cement. Geopolymer cements are formed by crosslinking silicates into 3D silico-aluminate structures (J. Davidovits, Geopolymer Cement, a review, January 2013). However, the conventional silicate-based geopolymer does not yet contain the necessary components to be used as such as the sole binder for concreting.

Brief Description of the Invention

It is an object of the present invention to provide a binder suitable for concrete or mortar that can be mixed with other dry constituents of concrete without the uncontrolled premature passage of the pozzolanic reaction before the addition of separate concrete water.

It is a particular object of the invention to provide a dry product suitable for the preparation of concrete or mortar and acting as a binder which as such contains the dry components required for the pozzolanic reaction.

The invention is thus based on the utilization of a novel process for the preparation of binder powder. The powder in question consists of composite particles or precursors thereof (by-products described below), which composite particles contain a kaolin portion and a lime-stone portion, the particles of which are adhered to one another.

By calcining, a pozzolanically reactive layer is applied to the particle surfaces of said portions, whereby the invention enables the production of a hydraulic binder moiety by the poszolane reaction, either with or without a separate Portland cement, and without the need for a separate hydraulic binder. These composite products can also avoid the addition of discrete fillers to end products utilizing hydraulic binders, such as concrete or mortar.

The pozzolanic reaction is particularly effected by means of metakaolin and calcium oxide or calcium hydroxide mixed with it.

The present invention thus relates to a process for preparing a powder containing composite particles formed by calcination of limestone and kaolin. By calcining, different portions of the composite particles can be activated, at least on their surfaces, to form a 4D binder powder. Thus, at least one portion of the composite particles has been calcined to convert it into a pozzolanically reactive form. In calcination, limestone is converted, at least in part, to calcium oxide (relative to limestone as determined by calcining conditions), whereas kaolin is at least partly converted to metakaolin.

The limestone particle particles can also be reacted on their surfaces to form calcium hydroxide, even before the use of the composite particles in, for example, concrete or mortar. From the limestone portion of this embodiment, agglomerates can also be formed by means of the invention, whereby the hydroxide on the surface of the particles first acts as a binder in the formation of the agglomerate and then optionally as a sintering agent in the formation of the Sint granule. More specifically, the process for preparing the composite particles of the present invention is characterized in what is set forth in the characterizing part of claim 1. The composite particle so produced, in turn, is characterized by what is stated in the characterizing part of claim 6, and the concrete product is characterized by what is stated in claim 12.

The invention provides significant advantages. Among other things, a method has been provided for bringing into concrete or mortar all the components required for the pozzolanic reaction in one dry product.

Because the composite particles can be brought into the concrete as a dry powder, it is possible to effectively mix all the dry ingredients in the concrete before adding water. This will significantly reduce premature hydration.

Separate concrete production is not even required when the powder of the invention can be produced separately, in a centralized industrial production.

The process according to the invention is not dependent on the calcium hydroxide produced by OPC nor on the timing of its production, but the requirements for concrete are determined by the so-called. yhdistelmäpartikkelinmäärä.

The reaction of calcium oxide with calcium hydroxide (quenching) produces heat which can accelerate the pozzolanic reaction and thus affect the early strength of the concrete. This early strength can also be increased by reducing the need for water. Since the non-toning water may also contain potassium hydrogen carbonate (Ca (HCO3) 2), the invention can also reduce the so-called. bleeding phenomenon.

Further, the invention can be used to improve the properties of cement and concrete without the high quality requirements of kaolin. In particular, the quality of the concrete (such as chloride resistance) can be influenced simply by adjusting the mixing step (including turbulence and homogenization) during manufacture.

The composite particle of the invention can be formed continuously, in particular by using economical and compact equipment. The small size of the equipment, in turn, allows it to be placed in a concrete station, thus maximizing the energy economy.

The invention will now be described in more detail with reference to the accompanying drawings and a detailed description.

Brief Description of the Drawings

Figure 1 illustrates various possible structures of kaolin.

Figure 2 is a microscope image (Figure 2A and Figure 2B) of a kaolin where the kaolin bundles have begun to disintegrate into particles.

Figure 3 is a schematic view of a calcining furnace according to an embodiment of the invention, in which also a possible connection to the pre-treatment section and the processing space is illustrated.

Figure 4 is a schematic view of an apparatus pre-treatment part of an embodiment of the invention combined with a processing space suitable for reacting calcium oxide to form a hydroxide.

Figure 5 is a more detailed schematic view of the stator portion (and its connection to the rotor portion) of the pretreatment portion of the apparatus according to an embodiment of the invention, wherein Figure 5A shows rotor blade and stator swivel blade positions relative to each other; differences between fixed wings.

Fig. 6 is a schematic view of an apparatus pre-treatment section and a processing space according to a particularly preferred embodiment of the invention, illustrating a portion of the hardware subassemblies described below and their locations within the assembly.

Fig. 7 is a diagram illustrating one way of assembling parts of an apparatus according to the invention to produce the composite products 1-3 of the invention.

Detailed Description of Embodiments of the Invention

The present invention relates to composite binder particles wherein the limestone moiety is combined with a kaolin moiety, wherein at least one moiety of the combination is in calcined form. In practice, the composite particles are produced by combining limestone particles (or particles containing limestone and silicate), at least on the surface of which have been calcined into calcium oxide (CaO), kaolin particles in which kaolin is optionally calcined to metakaolin.

The limestone portion is composed of limestone containing particles, whereby this portion preferably consists of either limestone particles or limestone-silicate particles. In the following, these will be referred to simply as "limestone particles". It has been found that by using both limestone and silica-containing particles in calcination, the silicate stone also receives calcium oxide on its surface.

Limestone thus refers, in the context of the invention, to a limestone material excavated which contains calcium oxide.

The composite particles or their calcined limestone fraction (CaO) can optionally be subjected to a quench reaction, whereby the calcium oxide in the limestone portion is further converted to calcium hydroxide (Ca (OH) 2).

Kaolin, in the context of the invention, is understood to mean a material containing various clay minerals, such as kaolinite, illite, vermiculite, smectite and chlorite. These clay minerals have a tetrahedral and octahedral moiety, and the relationships between these moieties (especially water and its ions in the structure) determine whether it is an inelastic or an expanding material.

Kaolinite, illite, and chlorite are non-expandable, whereas vermiculite is moderately expandable and smectite is highly expandable (Figure 1). These expansion properties (and the resulting particle sizes) can be utilized to activate the kaolin portion of the products of the invention. The kaolin utilized in the present invention is preferably> 50% kaolinite.

Optionally, kaolinite can also be formed into sialates, such as polysilates, of which the various sylate structures of the sodium, potassium and calcium ions are common, such as poly (sialate), poly (disialate), poly (sialate-siloxo) and poly (sialate-disiloxo). These occur in particular in the mineral structure of sodalite, sanidine, leucite, calcilite, and anorthite. This modification of the kaolinite can be accomplished, for example, by polycondensation of the kaolinite at elevated temperature and pressure using an aqueous alkaline solution (such as a NaOH solution).

Based on the above, the present invention provides four main products:

Product 1 is a composite particle in which calcination of the alloy has caused the limestone particle to be converted from its surface to calcium oxide, and at the same calcination has reacted kaolin to metakaolin. This composite product 1 already contains, as such, a small amount of aggregate required for concrete, not just binder alone.

Product 2 is the corresponding composite particle in which the calcination of the alloy has reacted the whole limestone to calcium oxide and at the same time made the kaolin react to the metakaolin. The difference with product 1 is thus that the limestone is entirely calcium oxide. This can be accomplished by selecting (in known manner) limestone particles of sufficiently small size or by intensifying calcination. These combination products 1 and 2 have the advantage, inter alia, of their functionality as pozzolanic binders.

Product 3 is a composite particle in which the metakaolin in its activated form is completely mixed with limestone particles calcined into calcium oxide, but the calcium oxide is further reacted to calcium hydroxide prior to mixing. This product has the advantage, among other things, of easy transport to the desired application.

Product 4 is a composite particle in which the activated form of metakaolin is mixed with limestone particles calcined into calcium oxide, but the calcium oxide is reacted to calcium hydroxide prior to mixing. In addition to these main products, the present invention makes it possible to produce a composite product 5, which is a spherical agglomerate formed from calcium hydroxide and metakaolin. This product has the advantage, among other things, of easy mixing with other dry ingredients of concrete, for example.

In addition to composite products, product and intermediate streams generated in the process of the invention can also be separated into fractions for use, for example, in the formation of the aforementioned composite products at various sites. The most significant of these are as follows: Intermediate 1 consists of limestone particles calcined at least on their surfaces to form calcium oxide. Intermediate 2 consists of limestone particles calcined at least on the surface into calcium oxide and further quenched into calcium hydroxide.

The product particles are all preferably smaller in size than 2 mm. Of course, composite particles in which the limestone portion is still partially (from the core portion) in the original limestone form are larger in size than those with the fully calcined (and optionally slaked) limestone portion.

Preferably said composite particles of limestone (or a mixture of limestone and silicate) of original cardiac content contain from 50 to 95% by volume, more preferably from 75 to 95% by volume, preferably about 90% by volume, of this core, the remainder being calcium oxide (or calcium hydroxide) and the kaolin content. In this surface area, the ratio of calcium oxide to metakaolin is preferably 1: 1 to 3: 1, preferably about 2: 1.

What these different combination products have in common is the fact that they all contain limestone and kaolin. All of these products and by-products, in turn, have in common the fact that they are recovered dry, i.e. solid, in powder form, easily transportable and mixed with other dry ingredients (and, of course, water), and containing at least one calcined component.

When the components of the composite products are brought together, said composite particles are formed in which the kaolin particles and the calcium oxide particles are bonded together through hydroxide. The hydrates contained in said combination products provide very good corrosion protection.

The limestone portion of the combinations is thus preferably based on limestone, the particles of which are obtained, for example, by crushing limestone obtained from quarrying, preferably to a particle size of 50 µm to 5 mm, whereby the fully calcined particles are preferably crushed to 50 µm.

As stated above, the limestone particles may be at least externally (possibly completely) in the form of burnt lime, i.e. calcium oxide (CaO). This step can be carried out, for example, by calcining.

Unless otherwise stated, the calcined limestone particles may in the following be either calcium oxide or calcium hydroxide with at least surface limestone particles.

The CaO layer formed by calcination constitutes 5-100% by volume of the total limestone-based particle. With respect to the particle diameter, which may be, for example, 50 to 1000 µm, this layer is preferably about 15 µm in thickness.

Optionally, this calcium oxide is further reacted to slaked lime, i.e., calcium hydroxide (Ca (OH) 2).

After the optional quenching reaction, the composite particle of the invention thus has a core particle at least on the surface in the form of calcium hydroxide (although oxide may be present) and at least one other material (in particular the kaolin portion of the composite particle).

According to one embodiment of the invention, the limed limestone is fractionated and the fractions containing particles of different sizes are separately subjected to further processing, or alternatively, the large limestone particles (> 20 mm) are crushed.

According to a preferred embodiment, the process of the invention comprises the steps of fractionating the limestone crushed into particles of suitable size (for example, through a sieve), mixing the desired fraction with the kaolin particles in a fluid state, adhering the kaolin particles to the limestone surface. Alternatively, the same calcination can also result in limestone-based particles which, at least on the surface, are in the form of calcium hydroxide (together with the kaolin particles), since the calcination converts this hydroxide to an oxide.

In another preferred embodiment, the method of the invention comprises the steps of grinding the limestone crushed into particles to a finer particle size prior to fractionation (e.g., through a sieve), burning the desired fraction into calcium oxide (CaO), mixing with kaolin or metakaolin particles in a fluidized and conducting this mixture to quench CaO to Ca (OH) 2. The kaolin-containing mixture (in its basic form) can then be subjected to calcination to give product 2. The metakaolin-containing mixture is already in the form of product 3 after quenching. During grinding, CaO-free surfaces are formed. The quenching reaction then occurs rapidly.

The crushing, optional grinding, and fractionation are preferably adjusted so as to obtain particles in the size distribution of 0.01 to 2 mm. More preferably, two or more of the following fractions are collected, most preferably all of the above fractions (according to the size of the largest screen-passing particles): 2 mm, 1 mm, 0.5 mm, and 0.25 mm

During calcination, the surface of the limestone-based particle is at least partially converted to calcium oxide, preferably 1-10%, preferably 1-5%. In particular, the calcination is adjusted to achieve a coverage of 10 to 100%, more preferably 10 to 85%, preferably 40 to 80%.

In general, it can be assumed that in the fraction containing the smallest particles, CaO is formed on the surface of the limestone at a higher coverage than in the fraction containing the largest particles.

Optional quenching of CaO is accomplished by adding water, preferably as water vapor and / or mist, to the mixture of limestone and kaolin moiety in an amount stoichiometric to the amount of water required to quench CaO. Kaolin and CaO are preferably mixed with each other in a ratio which corresponds to a substance combination produced by them which is theoretically 1 / 1.35 (kaolin / calcium oxide) and practically 1/1. Thus, the present invention preferably uses a ratio of 1/1 to 1 / 1.4. The addition of water vapor is preferably carried out with stirring to form a substantially homogeneous fluid. The resulting reaction mixture is then subjected to a processing in which the quenching reaction of CaO is completed while allowing the nano- or micro-sized calcium hydroxide (Ca (OH) 2) formed to adhere to the surface of the kaolin particle. During this processing, the temperature of the reaction mixture rises to about 200 ° C.

Due to the hydroxide formed, the kaolin portion of the reaction mixture particles and the calcium oxide portion of the particles bond to each other at their surfaces. The attachment (or adhesion) of Ca (OH) 2 to the surface of a kaolinic particle occurs without a chemical reaction, by physical forces (such as by charge). The criterion for the amount of Ca (OH) 2 on the kaolin surface is its corrosion protection to the steels in the final product (especially in concrete). For example, for a complete pozzolanic reaction, 1 kg of metakaolin requires the same amount of Ca (OH) 2 as it produces about 10 kg of Portland cement.

Either in the quenching of CaO due to the added water or due to the rapid rise in temperature (calcination), the kaolin in the form of fractions decomposes into smaller particles (Fig. 2) and thus becomes more suitable for the present invention.

The kaolin used as the raw material must be in a reactive form (in the form of kaolinite) in which it could participate in the pozzolanic reaction. However, final activation (i.e., reacting the kaolin to the metakaolin) occurs during optional calcination.

During calcination, the kaolinite mineral as part of the kaolin is burned at high temperature, whereupon it is activated and forms, at least in part (especially on the surface) high-reactivity metakaolin preferably> 40%, more preferably 40-60% and most preferably about 50%.

Al 2 Si 2 O 5 (O H) 4 → Al 2 O 3 · 2 SiO 2 + 2 H 2 O

The high temperature first causes (at 100 to 200 ° C) the removal (by evaporation) of the absorbed water, which begins the reorganization of kaolinite. Thereafter, as the temperature rises further, dehydroxylation begins, whereby also bound water is removed. This combustion causes so-called "kaolin". activation, that is, the formation of metakaolin.

The term "kaolin particles or a portion of kaolin" as used herein refers to particles in the form of either kaolin or metakaolin (or kaolin particles reacted with metakaolin on their surfaces).

The calcining of the invention is preferably carried out at a temperature> 500 ° C, more preferably 600-800 ° C, most preferably about 700 ° C.

By lowering the temperature, e.g., by 100 ° C, after reaching the highest calcination temperature, and maintaining this reduced temperature for a period of time, preferably> 10 minutes, until the desired end result is achieved, the proportions of activated kaolin or limestone can be adjusted.

During the crushing and optional grinding of limestone, there is always some dusty limestone, which during calcination is formed as loose calcium oxide.

As discussed above, both limestone and kaolin may only partially react during calcination. Particularly preferably, in such calcined particles, kaolin is about 50% in the form of kaolin and about 50% in the form of metakaolin, while the calcium oxide is in the form of 20-100% in the form of calcium oxide, and 0-80% in the form of calcium hydroxide. This results in a calcined composite particle which enables the hydraulic binder to be produced by the pozzolanic reaction, either in combination with a separate Portland cement or as such, the only pozzolanic binder. When the particle of the invention is used as the sole pozzolanic binder, the water-induced pozzolanic reaction is effected by the use of metakaolin and microsized (or nanosized) calcium hydroxide and calcium oxide particles on its surface. Thus, in the context of the invention, "pozzolanicity" refers to the ability of the silicate in kaolin to react with calcium hydroxide to form calcium silicate hydrate.

Alios · 2SiO2 + 8Ca (OH) 2 + 7.34H2O → 2 (2CaO · SiO2 · 1.17H2O) + 4CaO · A1203 · 13H20 As a result of this pozzolanic reaction, the limestone particles provide a corrosion-resistant and polymeric network coat which also helps limestone fraction to kaolin content of composite particles.

The composite particle of the invention may also be formed into a Concrete product containing one or more binders, at least a portion of which is a pozzolanic binder. Thus, 25-100% by weight of the total dry weight of the binder is the above-mentioned composite particle, and the remainder is preferably Portland cement.

The composite particles according to the invention give concrete in particular early strength and porosity, whereby its frost resistance is very high. The reaction of the calcium oxide contained in the pozzolanic binder with water also forms a larger size calcium hydroxide which compensates for the shrinkage in the concrete. The pozzolanic reaction also generates enough heat to raise the temperature of the concrete product by about 30 ° C.

The products and intermediates of the invention may be prepared by the apparatus described below.

The apparatus includes at least a calcining furnace 1 (Figure 3). Such a furnace 1 preferably includes vibrators 11 for providing kinetic energy to the particles to be treated and for conveying them from the feed end of the furnace 1 to its outlet end.

It is also possible to use a corresponding calcining furnace as a kiln for the raw material 23 to react, at least on the surface, with calcium oxide (CaO).

The heat or radiation energy required for the calcination or incineration reaction, in turn, is preferably provided by electric resistors or other heating elements 12 disposed in the furnace 1 (or 23).

Preferably, the calcining furnace 1 also includes a storage space 13 for storing calcined or burned particles where the temperature can be lowered than in furnace 1, as well as drain screws 14 disposed at the outlet end of furnace 1, through which the calcined particles are collected.

The calcining (or incineration) temperature is preferably from 500 to 800 ° C, preferably from 600 to 800 ° C, and the residence time in the furnace is generally 10 to 20 minutes. The rebellion produces activated particles from kaolin, which are easily adhered to calcium hydroxide, for example, by simple physical forces such as van der Waals forces, or adhere to matrices such as rubber and other polymers.

The limestone raw material can also be processed in separate parts of the plant, for example, to burn it at least from the surface of the particles to CaO. Because a natural product (limestone) is available here, which is available in various sizes, it is according to one embodiment subjected to crushing before the actual processing. This step is performed especially if the average particle diameter of the raw material is> 20 mm. Metals can also be removed from the raw material. Thus, optional auxiliary components are selected from the group comprising raw material dispensing and processing means 32 generally disposed in the equipment prior to other processing components, which in turn include, for example: o particle fractionator or crusher 21 (preferably precursor fractionator), limestone crude. for crushing the material into smaller (<20 mm) particles, preferably in the form of a notched roll, or for separating limestone particles of different sizes from each other and transporting them for separate further processing, o horizontal apparatus 22 for controlling feedstock feed, or o for feedstock furnace 23, CaO. , to form at least on limestone surfaces, or to form kaolin in the form of metakaolin, o or more of these (e.g., both crusher 21 and horizontal equipment 22), - or metal removal means 3, preferably disposed in the equipment so as not to interrupt flow of processable material passing through, including: o a metal detector 31, or o a metal separator 32 optionally coupled to a metal stripper 33, o or both (both a detector 31 and a separator 32 which optionally includes a stripper 33).

However, if limestone with a diameter of <20 mm is used, it may be subjected to grinding or fractionation without separate (post-quarry) crushing.

It is also common to place the limestone and kaolin tanks 4 required for the storage of the raw materials in connection with this particular apparatus, whereby they are preferably placed immediately before the particle crusher 21, if any.

The apparatus also includes: - a particle pre-treatment and mixing part 5, in which the limestone raw material (<20 mm particles) can be mixed with kaolin in a fluid state and processed into particles of a desired size, preferably by means of a blow-diffuser.

According to one embodiment of the invention, the calcium hydroxide may be formed by a hardware section optionally attached to the pretreatment section 5 comprising (see Figure 4): a processing section 6 wherein the material derived from the pretreatment section 5 can be reacted to convert calcium oxide to , and - optionally one or more accessory parts.

The processing part 6 connected to the pretreatment part 5 performs a quenching reaction of burnt lime (i.e., calcium oxide):

CaO + H 2 O -> Ca (OH) 2. According to this embodiment, the particles obtained from the raw material, at least in the form of CaO, are ground in the pre-treatment section 5, in particular to the micron class, for example, particles having an average diameter of 1 to 20 µm. At the same time, the CaO particles absorb water to their surface and at least partially enter their pore structure. Because of the very small amount of water, the quenching reaction does not occur to a significant extent in this pre-treatment section 5. However, the quenching reaction is completed in the processing section 6 of the apparatus.

Kaolin does not react significantly when exposed to water, but any Kaoine packages that may be present may be broken down into smaller particles, yielding the desired particles. These particles also attach to the formed hydroxide.

Hardware components can also be utilized to adjust process conditions or to adjust product properties such as purity.

The apparatus pretreatment portion 5 includes the following auxiliary portions: a rotor portion 51, a stator portion 52, and a water mist generator 53. Thus, the pretreatment portion 5 has a single rotor portion 51 preferably at a speed of 200 to 900 m / s. Its rotation speed and direction of rotation are adjustable, preferably by adjusting the peripheral speed (wing speed) to 100-900 m / s, more preferably 100-300 m / s, most preferably 300 m / s.

Similarly, the pretreatment section 5 has one stator section 52 comprising stator blades 52a, b, preferably of steel and V-shaped and arranged in a ring, in particular such that the outer ring has a pivotable blade 52a for adjusting the blade angle 52b. solid. This stator member 52 is arranged such that the CaO particles accelerated from the rotor member 51 can be impacted by said stator vanes 52a, b at a suitably adjusted impact angle (see Figure 5). This is intended, among other things, to adjust the ratio of radial velocity to tangential velocity.

The rotor portion 51 and the stator portion 52 combined so that particles from the rotor portion 51 can be guided to the stator portion 52 are well suited for grinding the particles. The water mist generator 53, such as a nozzle, in turn, can be used to spray water into this pre-treatment section 5 which thus functions as both a refiner and a pre-hydration chamber.

The high rotation speed of the rotors allows the use of small diameter rotors (such as 250 to 600 mm diameter), and the rotating blades 52a of the stator can control the radial speeds and the magnitude of the impact on the particle. The device thus uses high-speed motors to bring the rotors up to 9000 rpm or up to 20,000 rpm. In this pretreatment section 5, the particles have an average delay of <1 s, typically 0.01 to 0.1 s.

Optional auxiliary components may be provided to the apparatus among those capable of promoting the operation or control of the pretreatment section 5, including: an amount of water dispenser 54 for adjusting the amount of and a stator 52 for controlling the blade angle adjustment, which is preferably coupled to the rotor portion 51 and the stator portion 52, or both (both dispenser 54 and adjustment means 55).

The hardware processing space 6 may include the following auxiliary part: screw part 61.

In the preconditioning section 5 described above, calcium oxide, kaolin and, for example, water for quenching calcium oxide are pretreated with strong turbulence. This gives the particles a strong attrition as well as shocks 51a / 12a, b (i.e. overpressure and underpressure pulses) of the blades of the apparatus, which further produce cavitation. Water mist (or vapor) that hits the surface of CaO, and condensing water, results in a quenching reaction of CaO, resulting in a thin film of Ca (OH) 2 which is partially broken by attrition.

The powdered and pre-hydrated slurry (i.e., fluid) formed by the apparatus pretreatment section 5 may be introduced into a processing space 6 having a two screw screw member 61, preferably a two screw screw conveyor 61, particularly preferably a two helix screw conveyor 61. In this screw member 61 a reaction whereby the hydroxide formation reaction is completed without substantially agitating the slurry to be added thereto. At the same time, the Ca (OH) 2 in the meta stage and the kaolin particles adhere to each other.

Optionally, the progress of the reaction can be promoted by raising the temperature, for example to> 100 ° C, preferably to 100-300 ° C, most preferably to 100-295 ° C. In process space 6, small attrition also occurs between the CaO particles, which promotes the reaction. This attrition is controlled by adjusting the speed of the two screws in the screw portion 61.

Because of the variation in the amount of CaO grit (i.e., particles of other materials in the raw material) to be processed, inaccuracies are created in the process, with little delay in adjustment (also by hardware). This causes slight vapor formation. With the help of the screws of the processing part 6 of the apparatus, the steam formed can be transported in the space formed by the screws of the screw part 61. from the discharge head either by its so-called to the feed head or directly to the equipment pretreatment section 5. The screw speed is thus adjusted as the process temperature develops. Water vapor also reduces the amount of air entering the processing space as it is introduced into this rotor crush feeder. If the steam is condensed before use, it is preferably made at a condensation temperature <120 ° C. When this condensation temperature is <100 ° C, a negative pressure is obtained, and when this temperature is> 100 ° C, excess pressure must be applied.

It is also advantageous to track the volume of the processing space 6 increasing towards its discharge end, whereby the equipment is not blocked by the expansion of the material to be processed.

In order to maintain a suitable reaction rate, the temperature in processing state 6 is preferably allowed to rise to a level> 100 ° C, more preferably 100-310 ° C, particularly preferably 110-300 ° C, most preferably 260-290 ° C.

Optional auxiliary components may be monitored from the set capable of promoting control of the processing space 6, and include: - temperature measuring means 62, preferably disposed within or below processing portion 6, more preferably screw portion 61 thereof, and communicating with rotor portion 51 and stator portion 5 52, preferably through these adjusting means 55, so that the temperature of the calcium oxide to be processed can be measured from the screw portion 61 to control rotor speed and stator blade angles, or separate heating means 63 preferably located in the processing portion 6, or (both measuring means 62 and heating means 63).

Some of the auxiliary portions of the preferred embodiments described above and their mutual positions are illustrated in Figure 6.

One way of combining the above described pieces of equipment to produce the various products according to the invention is illustrated in Figure 7. The particles thus prepared can be used, for example, as a binder in concrete, mortar or rubber, or as a filler, especially paper.

The manufactured product has good opacity and has many different adhesion mechanisms that provide good adhesion in the final applications.

The following examples are not intended to limit the scope of the invention, but merely to illustrate the products and advantages thereof that may be obtained with certain embodiments.

eXAMPLES

Example 1

Product 2 according to the invention was formed using an alternative method in which wholly calcined limestone particles (0 <0.25 mm) were mixed with kaolin in a fluid state, screw quenched (to give Product 3), and further recycled to obtain the desired product 2. ). Indirect analysis was performed to determine the relationship between CaO and Ca (OH) 2 after calcination.

The mixture used in the reaction: kaolin 5.6 kg

CaO 4.4 kg total 10.0 kg

1000 g of the mixture was taken for analysis and quenched and calcined to give a product mixture containing, in addition to kaolin, 440 g of a mixture of CaO and Ca (OH) 2 formed by water. This product mixture was titrated with 1000 N HCl using phenolphthalein as an indicator, on the basis of which the ratio of CaO to Ca (OH) 2 was calculated. The analysis results are given in Table 1.

table 1

Example 2

Calcined limestone particles collected at different fractions at 800 ° C were used as Intermediate 1. These calcined intermediates (at least the calcified limestone particles on the surface of CaO) were titrated with 1000 N HCl using phenolphthalein as an indicator, and the amount of CaO in the particles was calculated. The analysis results are given in Table 2.

Table 2

Example 3

Calcination was carried out at 800 ° C for mixtures of limestone-stone particles (5.00 g) collected in different size fractions and 0.25 mm sieve-permeable kaolin particles (2.00 g) and allowed to cool at 700 ° C for 10 minutes at 700 ° C. I drive. Lowering of the corresponding mixtures at lower temperatures was also performed. Combined extracts 1 and 2 were thus formed. These calcined products (about 50% at least calcareous limestone particles and about 50% silicate) were titrated with 1000 N HCl using phenolphthalein as an indicator, which was used to calculate the amount of CaO. on the surfaces of limestone particles. The analysis results are given in Table 3.

Table 3

The fraction of the smallest size is thus calcined to ca. 90%, i.e. substantially completely, to CaO.

Claims (13)

A process for producing composite particles which act as a binder, which composite particles contain a limestone portion based on limestone particles or limestone silicate stone particles, characterized in that - the limestone portion is mixed with a kaolin portion containing the kaolin particles or the limestone portion is excreted or limestone particles or the mixture of these portions is subjected to calcination, wherein the activated layer formed during the calcination provides on the surface of at least one particle's particles, that the particles of the particles are adhered to each other to composite particles, and - at least the limestone particles or limestone silicate stone particles , where they react to calcium oxide at least on their surfaces, preferably to 10 - 100%, preferably to 10 - 85%, most preferably to 10 - 50%, and - a quenching reaction of calcium oxide is carried out by means of a water mist. calcium hydroxide is formed on the surface of the limestone particles or limestone silicate rock particles. Process according to claim 1, characterized in that the kaolin particles are formed from raw materials containing kaolinite, illite, vermiculite, smectite or chlorite or two or more of said minerals, preferably at least kaolinite, most preferably> 50% kaolinite. Method according to claim 1 or 2, characterized in that at least the kaolin particles are calcined under conditions where they are activated to metakaolin at least on their surfaces, preferably to> 40%, preferably to 40 to 60% and most preferably to about 50%. Method according to claim 1 or 2, characterized in that the quenching reaction of calcium oxide is carried out so that calcium hydroxide particles having an average diameter of <100 nm are formed at least on the surface of the limestone particles or limestone silicate rock particles. Process according to one of the preceding claims, characterized in that the calcination is carried out at a temperature of> 500 ° C, preferably of 600 -800 ° C, most preferably of about 700 ° C. 6. Composite particles which are intended to be used as binder of concrete and which contain a limestone portion based on limestone particles or limestone silicate stone particles, characterized in that - the limestone portion is bonded to a kaolin portion containing kaolin particles, wherein at least one portion comprises are at least partially in a calcined form, - the limestone particles or limestone silicate stone particles occur in a form in which they react to calcium oxide at least on their surfaces, preferably at 10 - 100%, preferably at 10 - 85%, most preferably at 10 - 85%. 50%, and - the calcium oxide of limestone particles or limestone silicate rock particles is in a quenched form, i.e. in a form of calcium hydroxide, said calcium hydroxide preferably being in the form of particles having an average diameter of <100 nm. Composite particles according to claim 6, characterized in that they are made by a process according to any one of claims 1-5. Composite particles according to claim 6 or 7, characterized in that they are smaller than 2 mm in size. Composite particles according to any one of claims 6-8, characterized in that the kaolin particles are selected from raw materials containing kaolinite, illite, vermiculite, smectite or chlorite or two or more of said minerals, preferably at least kaolinite, most preferably> 50%. kaolinite. Composite particles according to any one of claims 6-9, characterized in that the kaolin particles are present in a form in which they are activated to metakaolin at least on their surfaces, preferably to> 40%, preferably to 40 to 60% and most preferably to about 50%. %. Composite particles according to any one of claims 6 to 10, characterized in that they are selected from the following: limestone particles or limestone silicate rock particles, the surface of which has calcium oxide layers which are bonded to metakaolin particles, which are completely reacted to calcium oxide particles, bound to metakaolin particles, completely to calcium oxide and further to calcium hydroxide reacted limestone particles, which are bound to metakaolin particles, limestone particles or limestone silicate stone particles, which on their surface react to calcium oxide and further to calcium oxide, and further to calcium hydroxide, and further to calcium hydroxide. , which are formed of limestone particles, which have fully reacted to calcium oxide and further to calcium hydroxide, as well as metakaolin. Concrete product containing one or more adhesives, at least part of which is pozzolant adhesive, characterized in that 25 - 100% of the total weight of the total adhesive is composite particles according to any one of claims 6-11. Concrete product according to claim 12, characterized in that the dry weight of the total binder comprises 0 - 75% of Portland cement.