EP3268500A1

EP3268500A1 - Method and device for granulating molten material

Info

Publication number: EP3268500A1
Application number: EP16711505.4A
Authority: EP
Inventors: Alfred Edlinger
Original assignee: Radmat AG
Current assignee: Radmat AG
Priority date: 2015-03-13
Filing date: 2016-03-14
Publication date: 2018-01-17
Also published as: WO2016145466A1; US20180057901A1; JP2018509373A; CA2979558A1; SG11201707251UA; AT516906A1

Abstract

The invention relates to a method for granulating molten material, in particular slags, in which the molten material is introduced into a granulating chamber, in which water is stored as a cooling liquid, wherein the molten material is quenched preferably by evaporation of water and granulated. An acid is added to the water.

Description

Method and device for granulating

molten material

The invention relates to a method for granulating molten material, in particular slags, in which the molten material in a

Granulation chamber is placed in the water as

Coolant is kept, the molten material preferably with evaporation of the water

quenched and granulated.

Furthermore, the invention relates to a device for

Implementation of this procedure. Mineral melts, for example blast furnace slags, are usually granulated with the aid of water to obtain an amorphous product which is in the glass phase, i. a metastable phase solidifies. After one

Milling process can be such a product as latent

hydraulically active component cements are admixed. The heat of fusion of the melt flow is at a

such procedure converted into a low-temperature heat of water and is not available. Mineral melts, such as blast furnace slags, must be extremely fast (about 10 ³ K / sec) below their

Recrystallization point (depending on the basicity between about 600 and 850 ° C) are cooled to obtain a cemented amorphous product. Under this

Recrystallization temperature can be found with a much lower cooling gradient Auslangen. To increase the slag-glass content of the granules and the slag grindability over a

To improve cold water granulation is in the

WO 01/051674 Al a boiling water granulation has been proposed in which the molten melt is introduced into a cooling water initially introduced with boiling temperature. This is the latent enthalpy of evaporation of the

Cooling water for rapid cooling available, whereby the slag-glass content is maximized. The granules surprisingly have a very low apparent density and floats on the boiling water, thereby significantly improving slag grindability over grindability when using cold water granulation. The granulate itself is discharged from the boiling water at a temperature exceeding the boiling point of the water, the adhesive water being discharged during the

Granules already evaporates, so that directly produces a dry granules. Since water is discharged together with the granules only in vapor form, there is no wastewater problem. Steam will be in the episode

condensed and recycled together with make-up water to cover the water vapor losses the granulator. The by-products formed in the slag-water reaction, such as H ₂ S remain in the condensation of water in the gas phase and are here in concentrated form, so that a meaningful and economical workup succeeds.

In addition to blast furnace slags have various slags such. Steelworks slags, non-ferrous metallurgical slags, artificial slags such as e.g. Slags from the primary Al electrolysis (Spent Potliner with lime carrier slagging up) contaminants. This is especially true for

highly problematic dusts from metallurgy, the Cement production (cement kiln bypass dusts) and the

Waste incineration, which should be slagged.

On the one hand, these impurities make it impossible to use them as active binders (for example in cements), on the other hand they are environmentally problematical and can in some cases only be deposited in hazardous waste landfills. Such impurities are e.g. Compounds of F, Cl, alkalis, S,

Heavy metals (e.g., Cr, V, Ni, Mo, Cu, Sn, Zn, Cd, Hg), rare earths, but also Fe and free lime and unreacted CaO and MgO, respectively.

The invention therefore aims to be molten

Granulating material, in particular slags, in an energy-efficient manner, wherein said impurities are to be separated in a simple manner or converted into usable substances. At the same time, the granules obtained should have a particularly high reactivity

get, for example, in the cement industry

To be used.

To solve this problem, the invention essentially provides in a method of the type mentioned that an acid is added to the water. As acid. may preferably be a mineral acid, in particular

Sulfuric acid, hydrochloric acid, nitric acid or phosphoric acid, or an organic acid, especially formic acid, acetic acid, fatty acid (e.g., stearic acid) or

Ligninsulfonic acid, or mixtures thereof are used. Particularly preferred is the use of sulfuric acid. Furthermore, a mixture of at least one mineral acid with at least one organic acid is preferred. The granulation is thus carried out using a

Acid bath, with the most diverse

molten feeds give many beneficial effects.

The liquid melt solidifies on coming into contact with the acid bath from the outside, whereby a part of the acid bath evaporates. As a result, in the reactor due to the turbulent flow and the bubbling of the boiling acid bath to further entry of mechanical forces and consequently to a further comminution of the

Melt particles, which also promotes heat transfer.

Due to the presence of sulfuric acid in the

Granulating water is a sulfating Granulation achieved in which a sulfation takes place at the micro level of the solidifying particles. This is an increase of imperfections in the microstructure of the granulated

Materials, i. the incorporation of foreign bodies at the molecular level, the sulfation to a drastic increase in hydraulic activity in the context of

Use of the granules as a hydraulic binder or as a mixed component in cements leads. As a result, the early strength of the binder can be significantly increased.

It has been found that the sulfation reaction or the etching of kalsilikatischen melts especially to the reaction products colloidal silica, various modifications of Ca (S0 ₄ ) ₂ , such as gypsum, anhydrite and hemihydrate, leading, which for the early strength of

Cement are responsible. Depending on the content of other major melt components such as MgO, Al2O3, Fe ₂ C> 3 apparently their sulfates or other by-products such as Ettringite, zeolites, etc. All of these groups of substances have interesting properties in terms of cement technology. Similar reactions have also been observed using acids other than sulfuric acid, especially acids stronger than the silica. There are then no sulfates, but the corresponding alkaline earth salts, which may be water-soluble in contrast to the sulfates.

As a result of the evaporation of water, which is extremely energy-dense, the melt is cooled more than 10 ³ K / sec below the recrystallization temperature (depending on the basicity between about 600 and 850 ° C.), whereby the granules are amorphous or nanocrystalline (with a basicity of CaO / Si0 ₂ of greater than 1.8) is obtained, which leads to optimal cement-technological properties.

Characterized in that the melt according to the invention

vaporizing water is quenched, the granules come to a lesser extent in contact with liquid water, resulting in the unwanted prehydration of

cement-technologically hydraulically active amorphous slags leads (C-S-H phase formation).

Furthermore, the addition of sulfuric acid leads to

Granulation to ensure that the halogens contained in the slag, in particular F and Cl, and the contained

Sulfur compounds (sulfites, sulfides) in the

Acid anhydride form (HF, HCl, H ₂ S) are converted, which are withdrawn with the vapor vapors and then to

corresponding acid can be condensed. Especially hydrofluoric acid has a high market value and can therefore be utilized in an economically advantageous manner. Another effect of sulfuric acid is that in the melt existing free lime with the sulfuric acid in largely insoluble gypsum (preferably as hemihydrate) reacts, which is required in the cement as a solidification regulator. Thus, granules are obtained which are in the

Essentially free of free lime is. In the case of using the granules as a hydraulic binder is the

Presence of free lime from a cement technology point of view undesirable, because the free lime expands in the presence of water and thus would break the desired bond.

The present process is particularly suitable for the granulation of blast furnace slag. Under one

Blast furnace slag is understood to mean a calcium silicate-aluminate melt with the following main constituents:

CaO:> 30% by weight, in particular 35-45% by weight, Si0 ₂ :> 30% by weight, in particular 33-38% by weight

ΆΙ2Ο3:> 6% by weight, in particular 10-13% by weight

Furthermore, optionally 6-12 wt.% MgO, 0.1-0.5 wt.% Fe, 0.2-0.4 wt.% Mn, 0.3-0.5 wt. Na ₂ 0, 0.7-0.8 wt .-% K ₂ 0, 1.2-1.9 wt .-% S and / or ~ 1 wt .-% Ti0 _{2 be} contained. The present method is also suitable for the

Granulation of other slags, e.g. alloyed

Slags that follow follow main ingredients include:

CaO:> 30% by weight, in particular 35-45% by weight, Si0 ₂ :> 30% by weight, in particular 33-38% by weight, - A1 ₂ 0 ₃ :> 6% by weight, in particular 10-13% by weight. In general, the method according to the invention is suitable and advantageous for melts which have a CaO / SiO ₂ ratio of 0.6-1.6, in particular 0.85-1.4. The present method is not only suitable for the

Granulation of blast furnace slag, but especially for the granulation of steelworks slags.

Steelworks slags contain embedded in the matrix Alite and Belit shares, by the effect of

Granulated water contained acid, in particular

Sulfuric acid, be opened or exposed. Alite (tricalcium silicate, short C ₃ S) and belite (dicalcium silicate, short C ₂ S) are important constituents of

Portland cement clinker. The invention obtained

Granulate contains increased proportions of alite and belite and is therefore particularly suitable as a hydraulic binder or as a component of composite cements.

Steelworks slags also contain high levels of

Iron and heavy metal compounds. Heavy metals, in particular chromium, in particular chromium (VI) oxide, are undesirable in the cement. The heavy metals contained are good acid-soluble and therefore readily dissolve in the acid bath, especially in the granulated water mixed with sulfuric acid. Iron also goes into solution and iron sulfate is formed. In the presence of Na arises

Sodium sulfate. Ferrous sulfate and sodium sulfate can be advantageously used for further use. Iron sulfate is used for example in wastewater treatment for phosphate precipitation.

Steelwork slags are often used with dolomite

Basenbildner offset. That's why Steelworks slags contain free MgO, which in the

Granulation chamber reacts with the sulfuric acid to magnesium sulfate, which can be separated in the sequence. Similarly, melted steel mill dust

granulated, the heavy metals contained dissolve in the acid bath as described above.

Furthermore, it has been found that the inventive method for the granulation of a mixture of

Blast furnace slag and steelworks slag is suitable. The mixture preferably comprises 50-70% by weight, in particular approx.

60 wt .-%, blast furnace slag and 30-50 wt .-%, in particular 40 wt.%, Steel mill slag. The steel mill slag used is preferably steel mill slag from LD steelmaking. Steelworks slag usually has one

Iron oxide content of 15-25 wt .-% and a

Chromium oxide content of 1200 ppm. Granulating the slag mixture in sulfuric acid gives FeS0 ₄

(divalent Fe), FeS0 ₄ is usually the

chromium-containing cement added to avoid the formation of 6-valent Cr via the redox reaction. Thus, with the method according to the invention a latent hydraulic binder can be produced, which can be used in an advantageous manner as a mixed cement component for the production of a high-early, chromium-stabilized cement.

The process according to the invention is also suitable for the processing and granulation of secondary slags, e.g. Ladle slags, slags and

Fine slag. Such slags are generally not recyclable and must therefore be dumped. The slags have a high fluoride content because fluorspar has been added to liquefy the slag melt. In the sulfuric acid bath, fluorine is liberated as hydrofluoric acid, which goes into the gas phase and can be easily separated after condensation.

When using highly basic slag melts in the process according to the invention, such. of LD steelworks slags, electric arc furnace slags,

Ladle slags and secondary slags, it is preferred if the basicity (CaO / SiO 2) of the slag is adjusted to a value of 0.85-1.4. The setting can

preferably by adding acidic components, e.g. Quartz sand, used foundry sands, blast furnace slag, flue dust from waste incineration plants, fly ash from hard coal power plants.

The inventive method is further suitable for the processing of spent carbonaceous

Cathode material, in particular spent cathode tubs from aluminum production. Used cathode sinks, also called Spent Potliners, fall in the

Aluminum production after the Hall-Heroult process in large quantities and make due to their high content

Toxic substances have always been a disposal problem. Spent Potliners are mixed with lime in a pre-process and melted down. The melt is then freed from carbon (eg gasified in a shaft furnace or dissolved in an iron bath) and slag is formed which essentially contains calcium fluoroaluminate. In the inventive granulation of such a slag using an acid bath, in particular sulfuric acid, calcium fluoroaluminate is in amorphous or partially crystalline Calcium sulfoaluminate converted, wherein further hydrofluoric acid is formed. Calcium sulfoaluminate is highly reactive hydraulically and is used, for example, as an early strength accelerator in composite cements.

The inventive method is also suitable for

Granulation of desulfurization slags that arise as follows. Pig iron, which comes from the blast furnace, has a high sulfur content and is therefore subject to desulfurization. The pig iron is placed on pans for this purpose and mixed with calcium carbide and calcium oxide. The calcium reacts with the iron sulfide (FeS) and the sulfur is converted into the slag as calcium sulfide (CaS). The slag is then removed. The problem here is that calcium sulfide is partially soluble in water and thus represents a threat to groundwater. For this reason, the desulfurization slag usually has to be disposed of in sealed special depots. Furthermore, the desulfurization slag is hazardous because the remaining calcium carbide portion reacts with water to produce the highly flammable gas acetylene.

When granulating the desulfurization slag below

Use of a particular with sulfuric acid

acidified granulating water and under oxidizing

Conditions will be the carbon content from the

Calcium carbide content of slag in water gas and

Ca (OH) ₂ / CaO converted. CaS is converted into Ca (OH) ₂ / CaO and H ₂ S. H ₂ S, for example, can be converted to elemental sulfur in the Claus process or it can

Due to the high H ₂ S partial pressure oxidized and hydrolyzed to sulfuric acid. As already mentioned, various organic acids can also be used instead of sulfuric acid, the carboxyl group of the respective organic acid evidently having a positive complexing effect on the alkaline earth ions (Ca, Mg), which increase the number of defects in the slag glass. In addition, it also further reduces the hydrolyzing action of the granulating water and thus increases the slag reactivity in the cement.

In the context of the invention it can be provided that the pH of the water is lowered by adding the acid. The pH of the granulating water is thus regulated by adding an acid or an acid mixture. With regard to the running during the granulation, above

described chemical reactions, the corresponding acid consumption is to replace this by tracking of new acid in the Granulierwasser. In this case, it is possible to proceed in such a way that the pH of the water is measured and the supply of the acid is controlled to a

to maintain the prescribed pH of the water. It is thus created a pH control loop to ensure a given pH. The pH specification is based on the respective circumstances. For example, the

Stoichiometry of the salt formation reactions can be adjusted via the pH-controlled acid addition.

In a conventional water granulation has the

Granulating water to a pH of about 8-11. This basic value results from the partial hydration of the melt in a water bath, whereby Ca (OH) 2 is formed. The addition of an acid is preferably carried out in the case of granulation of blast furnace slag in such an amount that the pH of the granulating water is lowered to a value of about 6-8. In the case of the addition of sulfuric acid, Ca (OH) 2 is bound by the sulfuric acid and thereby neutralized, with a thin Gipsaut on the

Slag particle surface arises.

The caused by the addition of acid pH lowering of the water occurs here in particular in areas of the

Water baths in which the acid is not yet with the

Melt or the granules has reacted. Such areas may be in the immediate vicinity of the acid task, preferably separate from the water application, or along a flow path in which the acid in the granulation chamber is supplied to the area of the actual granulation. It is preferably possible to carry out a plurality of pH measurements along the flow path in order to determine the dynamics of the reaction conversion (kinetics of sulfation). From this, a criterion for controlling the shear forces determining rotor speed can then be formed. These shearing forces

affect the speed of

Sulfatization reaction significant.

In general, the amount of acid addition depends, inter alia, on the chemical composition of the granules to be granulated

Melt, in particular of the CaO content of the melt, and the desired amount of colloidal silica in

Granules off. Furthermore, the amount of acid addition depends on the throughput of the melt, ie on the amount of melt introduced into the granulation chamber per unit of time. A preferred procedure provides, in the case of the addition of sulfuric acid, that H ₂ S0 _{4 is added} in an amount of 2-15% by weight, in particular 2-10% by weight, per unit time, based on the weight of the molten material added in the unit time.

The acid is preferred to the water continuously

added.

In the granulation of steel mill slag, a larger amount of acid, especially sulfuric acid is required to lower the pH of Granulierwassers compared to the granulation of blast furnace slag. Steelworks slag contains free CaO and FeO, which reacts with sulfuric acid, so that only a subset of the supplied sulfuric acid is actually usable for the pH reduction. Preferably, the pH is lowered by the acid addition to a value of about 5-6 and by means of the pH control loop described above at this value

held .

In the context of the process according to the invention, it is possible to lower the temperature of the mineral melt below its recrystallization temperature and salt decomposition temperature by the evaporation of water, in which case the

Water vaporization enthalpy crucial importance. The molten material is preferably introduced at a temperature of 1250-1700 ° C in the granulation chamber and cooled suddenly.

To improve the cooling performance, the strongly endothermic heterogeneous water gas reaction can be used in addition to water evaporation. The method is preferably carried out in this context such that

Carbon and / or carbon-containing compounds, such as hydrocarbons, introduced into the granulating chamber to cause a water gas reaction. In addition to the advantage of improved cooling causes the

Water gas reaction the emergence of economic

recyclable gaseous products such as in particular CO and H2. Here, therefore, the sensible slag heat (about 450 kWh / t) is partially converted into chemical energy in a very advantageous manner.

The supporting water gas reaction is also very advantageous if certain slag contents are to be reduced "in situ". The water gas reaction causes, for example, a reduction of chromium (VI) oxide

Chromium (III) oxide. Furthermore, a Zn metallization, a Nickelelsalzreduktion and a phosphate reduction

respectively.

The granulation water held in the granulation chamber can be designed as a water bath into which the molten material is poured. The water bath is kept at a temperature such that the introduced through the molten material

thermal energy to an evaporation of the

Granulation while simultaneously quenching the melt leads. It is preferably provided here that the molten material is introduced into a water bath initially charged with boiling temperature. The introduction of the melt preferably takes place through the interior of a dip tube immersed in the water bath and open at the bottom.

Alternatively, it can be provided that the liquid

Granulating water is held only in a lower region of the granulating chamber in a sump. The molten material is preferred in this case 00027

15 above the preferred below the boiling point

introduced water sump, i. Not

poured directly into the water. By the with the

introduced melt registered thermal energy, the water of the sump is evaporated and there is superheated steam. The solidified melt particles are removed in this embodiment together with the superheated steam via a discharge opening and the

Melt granules are placed in a separator such as e.g. in a cyclone separator, separated from the H20 dam f. The separated superheated but pressureless steam is exergetically valuable and can be reused accordingly. The

deposited dust-like hot granules are preferably cooled to below 100 ° C, e.g. by air.

The withdrawn steam stream with the granules should preferably have a temperature of 200-600 ° C. The

Temperature control is preferably carried out by

Adjustment of introduced into the granulation chamber

Amount of water. For this purpose, a desired value of the temperature of the withdrawn water vapor is given and the temperature of the water vapor is measured, the measurement being e.g. at the outlet of the separator (e.g., cyclone separator). If the setpoint is exceeded, the amount of water introduced into the granulation chamber is increased. Will the setpoint

falls below, in the granulation chamber

introduced reduced amount of water.

To achieve the finest possible particles, the

Granulation of the melt is preferably carried out so that the molten material in the granulation chamber of a mechanical disintegration by means of a

Desintegrators is subjected. The expanding Water vapor additionally supports the grinding work. Preferably, the molten material is thereby

applied directly to the disintegrator. The

Mechanical disintegration is advantageously carried out by means of a rotor, which is preferably arranged directly below the feed point of the molten material, so that the material impinges on the rotor in the molten state. The rotor can in this case be arranged so that its axis of rotation is substantially aligned with the introduced melt jet. Furthermore, it is preferred if the point of impact of the melt on the rotor of liquid granulating water is kept substantially free, in particular by the said

Dip tube.

The disintegrator is intended to inter alia

Apply shear forces on the introduced melt. In an embodiment of the disintegrator as a rotor, the melt is thrown radially outward by the rotation and in this way further divided. The disintegrator, in particular rotor, preferably has guide elements, such as e.g. Shovels on which cavitation is induced. The cavitation is on the one hand by the shear forces

favors the slag due to the

Centrifugal forces is exposed, on the other hand, by the sudden evaporation of Granulierwassers. In the micro range, vapor explosions occur, followed by implosions, which results in extremely intensive comminution of the forming granulate particles. The height

Grinding fineness of the obtained in this way

Slag particles increase the hydraulic

Activity potential, so that a cement technology use is favored. A further increase in the fineness of the granules obtained can preferably be achieved in that the

Desintegrator, in particular the rotor in the direction of

Rotary axis reciprocates axially, preferably is vibrated. Preferably, a frequency of the outward and

Movement of> 100 Hz, preferably> 500 Hz, preferably> 1 kHz, in particular> 20 kHz (ultrasound) are selected. In order to reduce the high thermal load of the rotor, in particular in the area of the task of the molten material, a preferred method provides that the water is passed through axial openings of the rotor or through at least one radially extending channel of the rotor, whereby a cooling of the rotor can be achieved. In addition, this is an additional cooling effect on the

molten material exerted because the guided by the rotor water after its exit into the

Granulating chamber as additional granulating water for

Is available, whose enthalpy of vaporization a

additional cooling effect brings with it.

The slag granules can be cooled in the granulation to a temperature of about 150-300 ° C, wherein the gaseous Granulierwasser is passed together with the formed, mostly porous granules in the optionally boiling water bath upwards. The vaporous granulation water can be withdrawn together with the reaction gases, such as HF, CO, H ₂ and SO ₂ , via a gas outlet. Furthermore, part of the possibly boiling granulation water (granulated liquor) can be used together with the above-floating granules

be continuously withdrawn via an overflow. The Overheated melt particles are freed of drainage water by dripping and evaporation processes, which leads to a further increase in hydraulic power, since these can not hydrate. The withdrawn granular liquor can be recycled to the granulation combiner as return water. The granular liquor contains dissolved solid components, such as heavy metals, FeS0 ₄ , Na ₂ SC> 4 and the like., Which concentrate due to the circulation of the water. If necessary, the mentioned are dissolved

Ingredients by means of a suitable separation unit, such. a filter, sieve, cyclone, a centrifuge or the like separated and discharged from the circulation.

Likewise, it can be provided according to a preferred variant of the method that the evaporated granulating water is circulated after condensation and is brought to the boiling point after the return.

A particularly preferred process variant provides that the granulation chamber is designed as a grinding media mill and the molten material with metallic

Abrasive media of the grinding mill quenched and the solidified material particles by the action of

Grinding media are ground.

In a preferred procedure, the acid is added to the granulating water at a point at which the molten material has already been subjected to partial cooling, so that the acid under its

Decomposition temperature remains. The addition of the acid at a cooler point compared to the melting task causes a reduction in the decomposition of the acid (in the case of H2SO4 this is a breakdown into S0 ₃ and H ₂ O avoided). At a Training in which the melt is applied to a rotating disintegrator, the acid task can be done on a radially opposite the central melting task farther out. The introduction of the

Melting can in one embodiment with above a sump of Granulierwasser arranged rotating

Disintegrator (rotor), for example, via running inside the rotor lines that open at a radial distance from the axis of rotation at the surface of the rotor. Alternatively or additionally, the addition of acid can also take place in countercurrent to the particles thrown radially outwards by the rotor, specifically

for example, by injecting the acid into the

Granulation chamber.

According to another aspect of the invention is a

Apparatus for carrying out the inventive

Method provided comprising a granulation chamber with a water basin for receiving a water bath

or -sumpes, a task device for the

molten material, a water inlet opening into the water basin, a supply for the acid and a discharge opening for the granulated material. A preferred embodiment provides that a sensor is provided for determining the pH of the water stored in the water tank, which cooperates with a volume control of the acid supply in order to maintain the pH of the water at a predetermined value.

The feeding device for the molten material advantageously comprises a dip tube projecting into the granulating chamber. A preferred training provides that in the

Granulation chamber in the area of Materialaufgäbe a

Disintegrator, in particular a rotor is arranged. The disintegrator, in particular the rotor is in this case preferably arranged adjacent to the water bath or to the sump.

Furthermore, it can be provided that the rotor axial

Having perforations or at least one extending in the radial direction channel for passing water. In particular, the rotor may have a channel which preferably opens into the feed region of the molten material for the introduction of reactive gases and / or

Have water vapor.

A particularly preferred embodiment provides that instead of a separate, in the granulation chamber

arranged disintegrators, metallic grinding media are responsible for the supportive disintegration of the solidifying particles. The execution is like this

in that the granulation chamber is designed as a grinding media mill filled with metallic grinding bodies. The molten material is thus introduced into a grinding media mill and quenched in contact with metallic grinding media of the grinding media mill and the solidified

Material particles are ground by the action of the grinding media. Preferably, the grinding mill mill has a housing formed by a drum which can be driven in rotation and is in particular a ball mill, lintel mill,

Drum mill, tube mill or screen drum mill formed.

Due to the deterrence of the molten material to metallic grinding media succeeds a very fast Cooling of the melt under the

Recrystallization, so that a hydraulically active, amorphous product with particularly high

Cement-technological activity arises. The fast

Cooling is achieved by the metal grinding media provide a very large surface available, so that upon contact of the melt, a rapid increase in the specific surface of the

Volume of melt takes place in order to dissipate the heat as quickly as possible. Another reason for the quick

Cooling is in the high heat storage number, i. the heat capacity related to the volume, the grinding media due to their material, namely metal. At the same time, the solidifying melt particles are comminuted by the grinding action of the grinding bodies, which likewise causes an enlargement of the surface available for heat transfer. The simultaneous deterrence and crushing by the grinding media further causes that already one

essential part of the crushing work in the

molten state takes place, so that the specific grinding work in comparison to the comminution in the solid state reduced to about half.

The slag melt is abruptly on the cold

Cooled bodies (quenched) and therefore does not come in contact with liquid water, which is known

Prehydration of cementitiously hydraulically active amorphous slags leads (CSH phase formation). In addition, the possibly superheated, pressureless steam which may be present in the grinding chamber activates the cement technology Potential. The grinding action of the grinding media described above, in particular the shear forces produced by them, significantly reduce the molecular localization states, which leads to a further increase of the metastable system state of the slag. In particular, a strong and very advantageous increase in early slag cement strength can be ascertained. Thus, the

Cement clinker content of mixed cements are drastically reduced and also the very advantageous clinker-free, sulphatic cement stimulation ("sulphate cement")

be performed.

The cooling power required to quench the introduced molten material is determined by the

Evaporated water produced according to the invention, an acid was added. The cooling takes place here by the heat of vaporization at the surface of the grinding media, so that the grinding media are cooled accordingly. For the deterrence of molten material

required cooling power is thus provided indirectly, namely by mediation of the grinding media, by evaporation heat available. The grinding media are used here as "intermediate carrier", which required

Heat capacity and thermal conductivity, the required surface and the volume required to increase the heat transfer provide. The metallic grinding bodies are on the one hand by the

Evaporated heat of the water cooled and take on the other hand, the corresponding amount of heat on the other hand in contact with the molten material for cooling the same again.

To cool the grinding media using the

Evaporation heat is preferably provided that the According to the invention, pH-regulated water or the steam is introduced via a multiplicity of openings into the grinding chamber of the grinding body mill, which are formed in an inner jacket delimiting the grinding chamber. The mill is in this case preferably double-walled, wherein between the inner shell and an outer shell a

annular cavity is formed, which is charged with water. This forms a water bath whose level is chosen so that a lower portion of the grinding media bed is arranged in a water bath. Due to the effect of heat, the water contained in the annular cavity is brought to evaporate and enters via the openings formed in the inner shell into the grinding chamber, where the required heat of vaporization removes heat from the grinding bodies and cools them. Due to the openings results in a on the Mahlkörperbett (especially in the axial direction of the grinding chamber)

even water or steam entry. In a preferred manner, the openings can be designed to converge towards the grinding chamber in cross-section or nozzles, in particular over the axial length of the grinding chamber extending slot nozzles, form, resulting in a

Pressure distribution and therefore leads to a homogenization of the water or steam inlet into the grinding chamber.

A preferred side effect of the water or

Steaming over the apertured inner sheath is to cause the grinding media to vibrate thereby improving the grinding effect and reducing the occurrence of the Leidenfrost effect. A further preferred embodiment provides that metal balls, in particular steel balls, as grinding bodies,

can be used, the diameter of which is preferably at least 15mm, in particular at least 20mm. In this way, the balls provide a sufficient mass

Available to ensure the required grinding performance. It also makes it a simple size

Differentiation between the grinding media and the milled feed enables what is e.g. following

Facilitates separation steps.

In principle, all metal balls can be the same size. However, an optimization of the grinding action can preferably be achieved by the metal balls having a predetermined size distribution. In this case, a size bandwidth is preferred in which the

Ball diameter between 15 and 30 mm.

To ensure an efficient grinding effect, the training is preferably developed such that the

Metal balls are set to form a moving ball bed in motion. The training of the moving

Ball bed can be done here in various ways. For example, the balls may be affected by the action of the flow of a gaseous medium, e.g. Air or

Steam to be moved. Alternatively or additionally, the movement of the metal balls can be produced by the balls being set in motion by moving drivers, for example by a stirrer, blades, guide plates or the like. Alternatively or additionally, the grinding chamber can be formed by a rotationally driven drum, on the wall of which the balls rise and then fall down due to gravity. The invention in this context prefers that the

Mahlkörpermühle is designed as a ball mill, tumble mills, drum mill, tube mill, stirred ball mill or sieve drum mill. As with all media mills, media and media are moved in the ball mill. This results in collisions between the grinding bodies with each other and between grinding media and walls. The regrind becomes

crushed when it is between the bodies. The comminution of the particles is thus done by

Impact, shear and impact stress.

The invention will be explained in more detail with reference to embodiments shown schematically in the drawing. 1 shows a first embodiment of a granulating device for carrying out the invention

2 shows a second embodiment of a granulating device, FIG. 3 shows a cross section of a granulating device designed as a ball mill, FIG. 4 shows a longitudinal section of the device according to FIG. 3 and FIG. 5 shows an enlarged detail of the device according to FIGS. 3 and 4.

In Fig. 1, a granulating device 1 is shown having a trained as a dip tube 2 feeding device for molten material 3. Inside the

Granulating device 1 is a granulating chamber 4

trained in a water bath with a

Water surface 5 is recorded. The discharge of the granulated material takes place via a discharge opening 7.

The dip tube 2 dips to just above a trained as a rotor 8 disintegrator in the water, so the introduced through the dip tube 2 melt jet 3 strikes the rotor 8 directly or only passes through a small layer of water, which evaporates abruptly. The rotor 8 is rotatably mounted about a rotation axis 9 and driven for rotation in accordance with the arrow 10. The slag jet 3 is preferably, as shown in Fig. 1, centrally placed, ie in the region of the axis of rotation 9 of the rotor 8. In the center 11 of the rotor 8 wiest this on a rounded or convex portion on which the melt jet 3 impinges and of there due to the rotation is thrown outwards. The rotor 8 is arranged substantially at the bottom of the granulating chamber 4. In a radially inner, central portion of the rotor 8, however, a sump or a mixing chamber 12 is formed below the rotor 8, which forms a recessed portion of the granulation chamber 4 and is filled with water. The rotor 8 has axial openings 13, through which the water is sucked out of the mixing chamber 12.

The rotor 8 has radially outward of the axial

Openings 13 guide surfaces 14, which act as a cavitator. The granulation water is in fact submitted at such a temperature that it is in the region of the introduction of the melt jet 3 or in the region of the rotor 8 due to the introduced with the melt thermal

Energy evaporates abruptly. The expanding steam causes together with the mechanical forces caused by the rotor 8, in particular shear forces, a grinding action on the solidifying melt particles, so that a very fine-grained granules formed. To the

Guide surfaces 14 leads the expanding steam in

Interaction with the mentioned forces in the micro range too Steam explosions followed by implosions, ie to

Cavitation, whereby an extremely intensive crushing of the forming granule particles is achieved. For cooling the central region 11 of the rotor 8, a feed channel 15 is provided, which runs in the interior of the shaft 16 of the rotor 8 and in the central region 11 for

Training radial channels 17 is deflected radially. About the supply channel 15 and the radial channels 17 can

For example, water or steam for cooling the central portion 11 of the rotor 8 are supplied. Furthermore, via the supply channel 15 and the radial channels 17 reactive gases, such as 0 ₂ , air, CI ₂ , S0 ₂ , CH ₄ and / or coal dust or hydrocarbons can be introduced together with air / 0 ₂ or water.

The solidified melt particles 18 leave the rotor 8 in the radially outer region of the same and rise due to their low density in the, preferably boiling, water bath upwards. In this case, a distributor 25 may be provided, which comprises, for example, blade body. At the bath surface 5, the solidified melt particles 18 are discharged together with the granulating water via the discharge opening 7 designed as an overflow.

The gaseous constituents are withdrawn via a reaction gas outlet, schematically represented by 21, which is water vapor and, for example, HF, CO, H ₂ and SO ₂ .

The water bath is now an acid, in particular

Sulfuric acid added. The acid is added via the water supply 6. The acid is added to the mixing chamber 12 added water at 19 added. The

Volume control of the acid admixing takes place here in

Dependence of measured values of a pH sensor 20 in such a way that a predetermined pH of the water bath is achieved or maintained, or depending on the chemical composition of the melt and the

Melt throughput.

The water supply is fed by return water, which is obtained from the discharge opening 7. The granulated liquor withdrawn via the discharge opening is subjected to at least one separation step for this purpose, in which the granules obtained are separated off. The return water obtained in this way is over the

Line 22 returned. To compensate for evaporated

Water is added to the recycled water at 23 additional water.

For the separation of contained in the return water,

In particular dissolved there components, such as FeS0 ₄ , Na2SC and various heavy metals, a subset of the water can be discharged at 24.

In the modified embodiment of FIG. 2 is the

Granulating only presented as a sump, in the chamber 12 below the rotor 8. The water is supplied via line 6 with a temperature below the

Boiling temperature introduced into the granulation chamber. In the sump can via the line 26 carbon and / or

Hydrocarbons are introduced in the

Granulation chamber 4 in addition to the granulation (with the aid of the evaporating water from the chamber 12) a

Cause water gas reaction. The frozen Melt particles are drawn off in this embodiment together with the water vapor and the forming water gas through the discharge opening 7 and in the cyclone 27, the melt granules 18 of the reaction gases (CO / H2) and H ₂ 0 vapor is separated. Via the channel 15, pressurized water can be introduced.

The acid addition can be carried out in the embodiment of FIG. 2 directly into the granulation chamber, i. Preferably, the acid is supplied via channels extending in the rotor 8, which open at a distance from the axis of rotation at the surface of the rotor, i. at a point where the temperature is below the decomposition temperature of the acid. The supply of acid is indicated by 19. Alternatively or additionally, the introduction of the acid can also take place via nozzles 19 ', with which the acid in countercurrent to the

Granules in the radially inwardly extending direction is injected into the granulation chamber.

In Fig. 3 and 4 is designed as a ball mill

Granulation device shown. In Fig. 3, a ball mill 28 is shown in cross section, whose

cylindrical drum 29 is rotatably mounted about the rotation axis 30. In operation, the drum 29 is driven to rotate in the direction of the arrow 31. The drum 29 has an outer jacket 32 and a grinding chamber 33 delimiting inner jacket 34. Between the outer shell 32 and the inner shell 33 is an annular cavity 35th

formed, which distributed over a plurality of regularly over the circumference of the grinding chamber 33, preferably

slit-shaped openings 36 is connected to the grinding chamber 33. Coaxially to the axis of rotation 30 opens a slag entry 37 into the grinding chamber 33, wherein the slag entry has a centrally arranged in the interior of the grinding chamber 33 slag tundish 38, the slot-shaped entry opening 39 extends in the axial direction of the drum 29 and is disposed eccentrically within the grinding chamber 6 ,

The drum 29 has at the slag entry 37 opposite side to a rotation axis 30 coaxial discharge opening 40, to which a

Discharge line 41 is connected (Fig. 4).

In place of the perforated inner jacket 34 or in addition to this is in the interior of the grinding chamber 33 in the axial direction of the drum 29th

extending spray bar 42, whose

Sprühöff ments are directed downwards. Inside the grinding chamber 33, a metal ball bed 43 is provided, the metal, in particular steel balls, the grinding body of the ball mill 28 form. The metal balls are in the operation of the ball mill 28 by the rotating in the direction of arrow 31 drum 29 as shown in Fig. 3 taken upwards (arrow 44) and fall after

Reaching a critical height due to gravity back down (arrow 45).

During operation of the ball mill 28, as indicated at 46, water is passed into a water supply annular chamber 20 arranged in the drum 29, which is separated from the grinding chamber 33 by a diaphragm 48. The diaphragm 48 is only in the region of the water inlet annular chamber 47 formed liquid-permeable, so that the water inlet annular chamber 47 a in the grinding chamber 33rd

trained water bath 49 feeds, which is always in

Bottom area of the drum 29 is located. In particular, the water of the water bath 49 fills the annular cavity 35 between the outer jacket 32 and the inner jacket 34 of the drum 29. As in the detail view according to FIG. 5

can be seen, the annular cavity 35 a

Variety of axial direction of the drum 29 extending partitions 50, so that in the annular cavity 35, a plurality of circumferentially adjoining chambers 51 are formed. Each chamber 51 is in this case connected via a slot-shaped opening 36 with the grinding chamber 33, wherein the slot-shaped openings 36 to the grinding chamber 33 have converging walls 52, so that there is a nozzle effect.

When the drum 39 is rotating, blast furnace slag 53 is now introduced into the grinding chamber 33 at a temperature of 1300-1600 ° C. via the slag tundish 38, wherein the

Blast furnace slag 53 passes onto the ball bed 43, which has a temperature of at most 400-600 ° C. The slag is attached to the surface of the metal balls of the

Ball bed 16 abruptly cooled. At the same time takes place due to the movement of the balls a division of the

Slag in solidifying particles. The solidifying particles are further comminuted by the milling effect of the ball bed 43 until they reach a minimum upper grain boundary of e.g. 60μιτι have to from the ball mill 28th

be discharged. The particles are in the

Ball mill 28 cooled so far that they have a temperature of 600 - 800 ° C or lower when discharging. The ball mill 28 can in this case be designed so that they Has at least two in the axial direction adjoining grinding spaces, which by a

Sieve device communicate with each other, and the grinding media are sized so that in each grinding chamber a higher grinding fineness is achieved to the previous grinding chamber. Alternatively, a mill cascade is conceivable. The longer the residence time of the particles in the mill, the deeper the ground particles are cooled, so that the exergetic utilization can be further improved.

Simultaneously with the cooling of the slag to the

Ball surfaces is carried out by the action of the water bath 49, a continuous cooling of the metal balls. The water is caused to evaporate by the heat imparted by the slag, requiring heat of vaporization which is withdrawn from the metal balls for the purpose of cooling them. Due to the sudden increase in volume, the evaporating water escapes via the apertures 36 formed as slit nozzles from the chambers 51, the nozzle effect due to the

Pressure gradient leads to an axial equalization of the outflowing amount of steam. The effluent from the chambers 51 steam leads to an additional mechanical action on the balls of the ball bed 43 so that they are excited to vibrate, which the grinding effect

improved.

Inside the grinding chamber is formed a mixture of superheated steam and the dust of the ground slag particles. The superheated steam / dust mixture is discharged via the discharge opening 40 and the discharge line 41.

Claims

Claims:

1. Method of Granulating Molten

Material, in particular slags, in which the

molten material in a granulation chamber

is introduced, is kept in the water as the cooling liquid, wherein the molten material is preferably quenched and evaporated under evaporation of the water, characterized in that an acid is added to the water.

2. The method according to claim 1, characterized in that the acid is a mineral acid, in particular

Sulfuric acid, hydrochloric acid, nitric acid or phosphoric acid, or an organic acid, especially formic acid, acetic acid, fatty acids (e.g., stearic acid) or

Lignosulfonic acid, or mixtures thereof is used.

3. The method according to claim 1 or 2, characterized

characterized in that the pH of the water is measured and the supply of the acid is controlled to maintain a predetermined pH of the water. -

4. The method according to claim 1, 2 or 3, characterized

in that the molten material is introduced into a water bath initially charged with boiling temperature or above a water sump initially charged with boiling temperature.

5. The method according to any one of claims 1 to 4, characterized in that the molten material in the granulating chamber is subjected to a mechanical disintegration by means of a disintegrator.

6. The method according to claim 5, characterized in that the mechanical disintegration is carried out by means of a rotor.

7. The method according to claim 5 or 6, characterized

in that the disintegrator is arranged at least partially adjacent to a water bath or to a water sump.

8. The method according to claim 6 or 7, characterized

characterized in that the water by axial

Breakthroughs of the rotor or by at least one extending in the radial direction channel of the rotor is passed.

9. The method according to any one of claims 1 to 8, characterized in that the evaporated water is circulated after a condensation and after the

Return is brought to boiling temperature.

10. The method according to any one of claims 1 to 9, characterized in that the granulating chamber as

Mahlkörpermühle is formed and quenched the molten material with metallic grinding media of the grinding media mill and the solidified material particles are ground by the action of the grinding media.

11. The method according to any one of claims 1 to 10, characterized in that the carbon and / or

carbonaceous compounds, e.g.

Hydrocarbons are introduced into the granulation chamber to effect a water gas reaction.

12. Apparatus for carrying out the method according to one of claims 1 to 11, comprising a granulation chamber with a water basin for receiving a water bath

or -sumpes, a task device for the

molten material, one in the water basin

opening water inlet, a supply for the acid and a discharge opening for the granulated material.

13. The apparatus according to claim 12, characterized in that a sensor for determining the pH of the im

Reservoir water is provided, which cooperates with a volume control of the acid supply to maintain the pH of the water at a predetermined value.

14. The apparatus according to claim 12 or 13, characterized

in that the molten material feeding device comprises a dip tube protruding into the granulating chamber.

15. Device according to claim 12, 13 or 14, characterized in that a disintegrator, in particular a rotor, is arranged in the granulation chamber in the area of the material deposit.

16. The apparatus according to claim 15, characterized in that the disintegrator, in particular the rotor is arranged adjacent to the water bath or to the sump.

17. The apparatus of claim 15 or 16, characterized

in that the rotor has axial openings or at least one channel extending in the radial direction for the passage of water.

18. The apparatus of claim 15, 16 or 17, characterized in that the rotor has a preferably opening into the task area of the molten material channel for the introduction of reactive gases and / or

Has water vapor.

19. The device according to one of claims 12 to 18, characterized in that the granulation chamber as filled with metallic grinding media grinding media mill

is trained.

20. The apparatus according to claim 19, characterized in that the grinding media mill one of a rotating

drivable drum formed housing, and in particular as a ball mill, tumbling mills, drum mill, tube mill or sieve drum mill is formed.

21. Device according to claim 19 or 20, characterized

in that the grinding bodies are formed by metal balls, in particular steel balls, whose diameter is preferably at least 15 mm, in particular at least 20 mm.

22. Device according to claim 19 or 20, characterized

characterized in that the grinding media mill has a grinding chamber delimiting, provided with perforations inner shell and an outer shell, wherein the inner and outer sheath define an annular space, which forms the water basin and is connected to the water inlet.