WO2012007385A1

WO2012007385A1 - Method for producing pressed articles containing coal particles

Info

Publication number: WO2012007385A1
Application number: PCT/EP2011/061619
Authority: WO
Inventors: Hado Heckmann; Josef Stockinger
Original assignee: Siemens Vai Metals Technologies Gmbh
Priority date: 2010-07-12
Filing date: 2011-07-08
Publication date: 2012-01-19
Also published as: CN102959058A; KR20130096705A; AT510135A1; US20130174695A1; CN102959058B; EP2593536A1; AT510135B1; EP2593536B1

Abstract

The invention relates to a method for producing pressed articles containing coal particles, to the pressed articles obtained in this way, and to the use of the pressed articles in methods for producing pig iron in a fixed bed or in methods for producing carbon carriers for methods for producing pig iron in a fixed bed. To this end, at least a partial amount of the coal particles is subjected to at least two impregnation steps in which they are impregnated with at least one substance before being mixed with a binder system containing water.

Description

Description OF THE INVENTION Process for the Production of Presslines Containing Carbon Particles

Field of engineering

The invention relates to a process for the production of pellets containing pellets, the pellets obtained thereby and the use of the pellets in processes for producing pig iron in a fixed bed or in processes for the preparation of carbon carriers for processes for producing pig iron in a fixed bed.

State of the art

In processes for the production of pig iron in a fixed bed, for example in

Melter gasifiers, or in processes for the preparation of carbon carriers for

Process for the production of pig iron in a fixed bed, for example coke production for blast furnaces, used compacts containing carbon particles, such as briquettes, must have a certain fall and pressure resistance after discharge from the press. The drop resistance is required so that the original size of the compacts in the course of charging in a process without prejudice to inevitable falls, for example when transferring from one to another conveyor belt or when charging in a material bunker, as much as possible. The

Compressive strength is required to maintain the original size of the compacts after being charged into a material bunker or fixed bed reactor, despite pressure exerted by superposed layers of material.

These strength requirements are also summarized under the term cold strength.

In addition to the cold strength and the hot strength of compacts - especially when used in thermal processes - a criterion for their suitability for use. In the particular case of using fine particle carbon particles containing pellets in pig iron production processes, such as in a melter gasifier or blast furnace, the term hot strength refers to a) strength remaining after pyrolysis of the pellets in a high temperature zone

Semi-coke or coke particles, and b) strength of these

Semi-coke or coke particles after a chemical attack of a hot, C0 ₂ -containing gas. A minimum level of hot-strength makes it possible, after the conversion of the compacts by pyrolysis in Halbkoks- or

Coke particles existing size of these particles is largely retained.

In the case of pig iron production in a fixed bed, the development of

Sub-grain from compacts or coke particles prior to charging in a fixed bed or within a fixed bed therefore undesirable, because this the permeability of the fixed bed is deteriorated. In the particular case of a procedure for

Pig iron production affects both gas permeability and gas

Drainage behavior of the fixed bed with respect to the molten pig iron and the slag. If the permeability of the fixed bed deteriorates, its productivity, its specific energy requirement and its detrimental effects are detrimental

To expect product quality.

From WO 02 / 50219A1 it is known to produce compacts with sufficient cold strength from fine-grained carbon particles by means of a binder system of quicklime and molasses. Here, fine-grained coal particles of fine coal and quicklime are mixed, the mixture for the purpose of progressing the quenching reaction with moisture from the coal particles rest, then added molasses, kneaded the resulting mixture and finally pressed from her pellets.

There are coals which show an extraordinarily high water absorption capacity, in particular characterized by a high inherent moisture content. For use in pig iron production, however, the moisture content of the compacts should not be too high, ie at a maximum of 7% by weight. This is because this moisture in the use of the pellets for pig iron production or for the production of carbon carriers for

Process for pig iron production energetically polluting, since the moisture content of the compacts, the specific consumption of carbon carriers increases significantly. Therefore, coals whose moisture is higher must be dried before processing into compacts. In addition to the unwetted pore volume already present in the undried coal, the expulsion of water from cavities in the

Drying produced additional pore volume. The unwetted pore volume can absorb a corresponding amount of water or aqueous media. Of course, the additional pore volume can again absorb water or aqueous medium. Moreover, certain coals also tend to have extra pore volume due to grain damage, especially during intense drying to generate. When drying a coal with a high water absorption capacity to an acceptable moisture before the application described in WO 02 / 50219A1

Process for the production of compacts, a large additional pore volume is generated. Therefore, a dried carbon particle sucks a significant portion of the molasses needed to form a bond on the particle surface, which is to be understood as an aqueous solution, into its pores. Therefore, for such coals with commonly used molasses additions of <10% by weight, based on the weight of the coal to be processed, sufficient strength for the compacts can not be achieved. However, in order to produce compacts with sufficient strength based on molasses binder, must

to dispense with the generation of unwetted pore volume by drying, or

the more molasses is added, as is absorbed by the pore volume and therefore not available for binding to the surface of the carbon particles.

However, these measures are undesirable for reasons of process economy.

Even with naturally less moist coals, which do not have to be dried to achieve a moisture content of the compacts of at most 7% by weight, some of the molasses is absorbed into the pores of the carbon particles. However, molasses contains components which act catalytically with respect to a reaction of carbon with hot, C0 ₂ -containing gases, whereby in particular in the hot zones of a production of pig iron serving fixed bed at temperatures> 800-1000 ° C, depending on the pressure, the extent a conversion of solid carbon with C0 _{2 increases} according to Boudouard reaction. As a result, the hot strength of molasses-treated compacts is relieved by pyrolysis-derived, semi-coke or coke particles.

The use of bitumen as a binder proposed in WO9901583A1 does not pose such problems associated with molasses. However, the production of pellets with bitumen is associated with very high binder costs.

The use of an aqueous bitumen emulsion as a binder system proposed in AT005765U1 reduces bitumen consumption by more than 50%. In practice, however, it has been found that the feeds of moisture substantially above 5% by weight, so that when using such bitumen emulsions stable compacts arise. There is also the problem that pores present in the carbon particles can absorb aqueous bitumen emulsion or deprive the emulsion of water and thus destabilize it due to droplet coalescence, before a substantially uniform distribution of the emulsion within the material to be processed into compacts and, correspondingly, uniform wetting the particle surface can be made through the emulsion. This reduces the effectiveness of the emulsion as a binder.

Summary of the invention

Technical task

The object of the present invention is to provide a process for the production of compacts, in which these disadvantages of the prior art are overcome, and compacts with sufficient green and hot strength even with the use of carbon particles, which must be pre-dried, using a known Lesser amount of a water-containing binder system can be produced.

Technical solution

This object is achieved by a method for producing a compact containing carbon particles, in which the carbon particles are mixed with a water-containing binder system and the resulting mixture is further processed by pressing into compacts,

characterized,

that before mixing with the water-containing binder system

at least a subset of the carbon particles is subjected to at least two impregnation steps in which it is impregnated with at least one substance. Advantageous effect of the invention

During the impregnation, the substance either penetrates into the pores of the carbon particles and accordingly prevents the penetration of components of the aqueous binder system by filling in the pore space. Or the substance settles in the Exit points of the pores on the carbon particle surface, also called pore necks, and prevents by this clogging of the pore necks penetration of components of the aqueous binder system in the pores.

In this way it is prevented that aqueous binder system, which is needed on the coal particle surface for binding purposes, can no longer fulfill these binding purposes after penetration into the pores. Accordingly, as compared with a method in which aqueous binder system can penetrate the pores, the amount of aqueous binder system required is reduced. Preferably, the coal particles to be processed into compacts become

or at least a subset of them, prior to the impregnation step, subjected to drying to a moisture content of less than 8% by weight, preferably to a moisture content of less than 7% by weight. A moisture in a range from greater than or equal to 4% by weight to less than 8% by weight is particularly preferred, a moisture in a range from greater than or equal to 5% by weight to less than 7% by weight is particularly preferred.

The aqueous binder system may contain one or more other components besides water.

The impregnation step may consist of steaming the carbon particles with the substance, spraying the carbon particles with the substance, mixing the substance into a moving bed of carbon particles, or mixing the substance into one

Fluidized bed of coal particles exist.

It may be subjected to at least two impregnation steps, a subset or all of the coal particles to be processed into compacts. It can also be three, four, five, six, seven, eight, nine, ten or more impregnation steps. If the total amount of carbon particles to be processed into compacts is subjected to at least two impregnation steps, the above-described effects of the impregnation will occur in the total amount of coal particles to be processed into compacts.

When a subset of the coal particles to be processed into compacts is subjected to at least two impregnation steps, less becomes

Impregnant consumed as in an impregnation of the entire Compacts to be processed coal particles. However, the above-described effects of impregnation occur in the subset and thus contribute to an improvement in the properties of the compact. A first impregnation will improve the efficiency and / or durability of a subsequent impregnation. With only one impregnation step, the effect caused by the impregnation may decrease with increasing age of the pellets - for example, such that the briquettes behave brittle after a certain time. A decrease in the by impregnation

caused effects, for example, by incomplete closure of the

Pores have been caused by the impregnating agent or separation of the impregnating agent from the pore walls, for example due to cooling and / or contraction.

If two impregnation steps are carried out, such effects can be reduced or prevented. It is particularly advantageous if

different impregnating agents can be used for the first and second impregnation steps. For example, in the second impregnation step, penetration and subsequent closure of pores that were still incomplete or not sealed after the first impregnation step can take place-because the impregnation agent in the second impregnation step is, for example, another

Viscosity and / or other wetting properties against the carbon particles has.

It may be advantageous if a subset or the total amount of coal particles to be processed into compacts is subjected to more than two impregnation steps. Unopened or unwetted pores remaining after a preceding impregnation step may be impregnated or wetted or sealed in one of the subsequent impregnation steps.

The carbon particles can be impregnated in all impregnation steps with the same substance. In different impregnation steps can also

different substances are used.

The substance with which it is impregnated is preferably used as a liquid or by means of a liquid for impregnation. As a liquid, for example, substances that are liquid at the temperature prevailing at the impregnation step are. Impregnation by means of a liquid denotes, for example, impregnation with substances which, although they are not themselves liquid under the conditions prevailing during the impregnation step, are emulsified or suspended in a liquid.

In contrast to the use of solid substances, the penetration into pores or the clogging of pore necks is thereby improved or even made possible in the first place.

In order to ensure that a substance used in the impregnation step remains liquid during the impregnation step, the carbon particles to be impregnated are preferably heated to a temperature at which the substance is liquid.

In one embodiment, the substance impregnated with the carbon particles in at least one of the impregnation steps is water.

Then, in the impregnation step, water is sucked into the pores which, as a result, no longer tend to absorb components of the aqueous binder system supplied to the carbon particles after the impregnation step. As a result, in previous methods, components sucked into pores and thus rendered ineffective for binding the compacts can make a contribution to binding the compacts.

By limiting the proportion of water impregnated compacts in a feed mixture for a pig iron production process in combination with

Carbon carriers having a low moisture content than these compacts can limit the water input into the pig iron production process to an acceptable level.

According to another embodiment, the substance with which carbon particles are impregnated in at least one of the impregnation steps is a water-insoluble and / or water-repellent substance.

If the pores are filled with such a substance in the impregnation step and the pore walls are coated with such substances, the tendency of the pores to absorb components of the aqueous binder system decreases. Will the

Exit points of the pores on the carbon particle surface of such substances closed, no components of the aqueous binder system can penetrate more into the pores. As a result, so far sucked in pores and thus for the Binding of the compacts ineffective components make a contribution to the binding of the compacts.

The water-insoluble and / or water-repellent substance preferably belongs to that from waxes, organic coking or refinery products, as well as plastics

or waste plastic existing group of substances. It can also be used oil. It can also be bitumen. These substances are usually available in large quantities at low cost. The impregnation step is advantageously carried out at a temperature at which the water-insoluble and / or water-repellent substance is liquid, in particular viscous. As viscous in this sense, liquids are considered whose viscosity is at least 1 Pas, and a maximum of 100 Pas, for example, 10 Pas. In these conditions, the substance spreads on the surface of the carbon particles and penetrates into the exit points of the pores but hardly into the interior of the pores. As a result, the consumption of the water-insoluble and / or water-repellent substance in the impregnation step is kept low. Advantageously, the water-insoluble and / or water-repellent substance solidifies on cooling in the exit points of the pores on the coal particle surface.

According to another embodiment, the substance with which carbon particles are impregnated in at least one of the impregnation steps is an aqueous solution of a substance or a mixture of substances. For example, it is molasses, which is an aqueous solution of a mixture of carbohydrates and other natural products.

In principle, dissolved substances of all kinds, which improve the hot strength and cold strength of the compacts, can be used, for example starch or lignin bases from waste liquors of pulp production.

It is preferred to use solutions of substances or mixtures of substances which are converted by heat treatment and / or chemical reaction into water-insoluble substances. This will ensure that those of these substances or

Substance mixtures caused effects are not diminished by the fact that they are dissolved in the water of the binder system containing water and flushed out of the pores. According to another embodiment, the substance with which the carbon particles are impregnated in at least one of the impregnation steps is an aqueous one

Suspension of solid colloids, wherein the solid has water-repellent properties. Examples include suspensions of colloidal talc, graphite or waxes in water. If the solids settle in the pores or in the pore necks, the entry of water-containing binder systems is made more difficult due to the high surface tension of the water-repellent solids.

According to a further embodiment, the substance with which the carbon particles are impregnated in at least one of the impregnation steps, an emulsion containing on the one hand water and on the other hand carbonaceous substances such as bitumens, raw tars obtained from hard coal, pitches, waxes, oils.

When such emulsions penetrate into the pores, the carbonaceous ones become

Substances deposited in thin layers on the pore surface. During pyrolysis, carbon films are formed from these thin layers. These reduce the reactivity of the compact to hot C0 ₂ -containing gases compared to an embodiment in which no thin layers of the substances are deposited in the pores. Such an effect also occurs if the substance with which the subset of the carbon particles is impregnated in the impregnation step is not an emulsion,

for example, if the substance is bitumen.

The occurrence of such an effect is due to the fact that the carbon layers formed from the substances contain little or no catalytically active substances with respect to reaction with hot C0 ₂ -containing gases. In contrast, contain the carbon particles or the material to be processed into compacts, catalytically active compounds, such as iron or alkalis. Accordingly, the

Reactivity of a compact whose surface and pores are covered with a carbon layer resulting from the substances, lower than that of a compact without such a carbon layer.

When coal particles are used, which require pre-drying before processing into compacts, it is advantageous for economic reasons not to advance the drying substantially below 5% by weight of moisture, ie to a maximum of 4% by weight of moisture. As a result, the formation of additional pore volume is limited as a result of drying and taken accordingly less substance in the impregnation step of pores. Accordingly, less is achieved in the impregnation step Substance consumed. In addition, less equipment and energy expense must be operated for drying.

The lower limit of the amount of substance added in the impregnation step, called impregnating agent, is 0.5% by weight, preferably 1% by weight, the upper limit is 5% by weight, preferably 3% by weight, more preferably 2% by weight, based on the weight of the compacts to be processed good, so the coal particles. Addition of more than 5% by weight of impregnating agent does not make economic sense. If less than 0.5% by weight of impregnating agent is added, impregnation is no longer effective.

According to one embodiment of the method according to the invention contains

Binder system molasses and quicklime or hydrated lime. It can also consist of these components.

According to other embodiments, the binder system contains molasses in combination with strong inorganic acids, such as phosphoric acid, sulfuric acid, nitric acid.

According to one embodiment of the method according to the invention contains

Binder system an emulsion of bitumen in water. It can also consist of such an emulsion.

According to further embodiments, the binder system contains products from waste liquors of pulp production, starches, cellulose, beet pulp, waste paper pulp, groundwood, or long-chain polyelectrolytes such as carboxymethylcellulose.

Since quicklime or hydrated lime binder systems have the disadvantage that quicklime CaO and hydrated lime Ca (OH) _{2 increase} the reactivity of the pellets against hot C0 ₂ -containing gases due to catalytic activity, have the Embodiments without lime or hydrated lime have the advantage of providing compacts with comparatively lower reactivity.

According to one embodiment of the method according to the invention also iron or iron oxide-containing particles are processed in a mixture with the carbon particles.

According to a particular embodiment of the inventive method, the

Pressings are subjected to a heat treatment after the pressing.

The heat treatment is carried out at a temperature higher than the pressure. The heat treatment causes a drying and / or hardening of the compacts. The

Heat treatment can be carried out at temperatures of preferably> 250 ° C and <350 ° C, where irreversible chemical processes can convert binder components.

For example, water-soluble binder components may be rendered water-insoluble

Connections are converted.

The compounds formed during such conversions can contribute to the

Strength of the compacts afford.

In the case of a molasses-containing binder system, for example, a conversion of molasses by caramelization. According to a particular embodiment of the inventive method, the

Coal particles after the impregnation step before mixing with the water-containing binder system subjected to a heat treatment.

The heat treatment causes a drying. In the event that solutions or emulsions are present in the pores, the heat treatment additionally causes a concentration of the solutions, suspensions or emulsions and, accordingly, one

Coating of the pore walls with dissolved, suspended or emulsified

Components. These may, in addition to the aqueous binder system added thereafter, contribute to increased hot strength and cold strength

Deliver pellets.

Furthermore, the heat treatment can be the transformation of the due

Heat treatment initially resulting coating the pore walls in water-insoluble compounds, or cause in the reactivity of the carbon particles to hot C0 ₂ containing gases lowering compounds. The

Maximum temperature of the heat treatment is due to the pyrolysis of the carbon particles limited and is at 350 ° C. The lower limit for the temperature at this

Heat treatment is 150 ° C.

If the same water-containing emulsion is used for the impregnation, as it is used as the water-containing binder system, so is in the

Impregnation step added amount less than that in the subsequent

Mixing added amount of water containing binder system.

For example, when using bitumen in water - emulsion in

Impregnation step and as a binder system is carried out in the impregnation step, an addition of 2 -3% by weight, while added as a binder later 7-10% by weight.

The same applies if the same aqueous solution of a substance or a mixture of substances is used for the impregnation, as it is used as the water-containing binder system. For example, when using molasses in the

Impregnation step and as a binder system is carried out in the impregnation step, an addition of 3 to 5% by weight, while added as a binder later 6 to 8% by weight. The limits of the specified ranges are included. In these cases, after the addition in the impregnation step, a heat treatment is necessary to remove the carrier liquid water so far that the emulsified substances or the dissolved substances settle in the pores or the pore necks. As a result, the pores are occupied or the

Pore necks blocked. Overall, therefore, less water-containing binder system is required for the production of the compacts as in a production without

Impregnation step.

The processing into compacts after the impregnation steps can be carried out by known methods, for example as described in WO 02 / 50219A1 or in AT005765U 1, or by any method suitable for processing coal particles with a water-containing binder system into compacts.

An inventive after the impregnation steps with a

water-insoluble and / or water-repellent substance addition of water-containing binder systems in the production of compacts reduces the process costs compared to conventional methods such as WO02 / 50219A1. The avoidance of a water absorption of the coal during the production of On the one hand, compacts containing water-containing binder systems reduce specific coal consumption in pig iron production processes in which the compacts or coke produced therefrom are used, since less water from the binder system is present in the compact and correspondingly less energy has to be expended for its evaporation. On the other hand, an in

conventional method for the production of compacts due to the absorption of water from the binder system occurring need for post-drying of the compacts when using the method according to the invention omitted, or the

Drying costs are reduced, resulting in an energy savings. Accordingly, since the provision or operation of devices for post-drying can be dispensed with, or the dimensions of the devices and the cost of their operation can be reduced, this is equivalent to operating cost and investment cost reduction.

As an additional advantageous effect of the impregnation steps, depending on the nature of the substance used for impregnation, a reduction in the C0 ₂ reactivity of the resulting after pyrolysis of the pellets in a melter carburetor or the cokes obtained from compacts may result. A low CO ₂ reactivity is desired in the operation of a melter gasifier so that the semi-coke in the fixed bed of the melter gasifier or the coke in the fixed bed of a blast furnace remain stable from the charge to the bed surface until reaching the immediate gasification zone in the area of the oxygen nozzles or the tuyeres and thereby promote the permeability of the fixed bed with respect to the gassing and the drainage of molten phases. The reduction of the C0 ₂ reactivity of the coke or the coke is achieved in that the inner surface of the pores of the carbon particles in the compact can no longer be coated by the impregnation of a binder which contains reactivity-promoting substances. For example, the binder component molasses contains alkalis as reactivity-promoting substances. If the impregnation, for example with substances containing bitumen or waxes, prevents molasses coating the inner surface of the pores, the C0 ₂ reactivity is thus reduced compared to semi-coke or coke obtained by a process without impregnation step. A minor proportion of undersized coke is commonly used in the COREX® or Fl N EX® process for the production of pig iron in a fixed bed of a melter gasifier

Charcoal added to improve the permeability of the fixed bed. at

Use of compacts according to the invention, or from such produced coke, a softening of the charcoal or coke particles is inhibited by hot C0 ₂ and thus counteracts a disintegration of the particles. , In fact, in the case of compacts produced according to the invention, it is also possible to determine an improved thermo-mechanical stability of the semi-coke relative to compacts produced in a conventional manner. Thermo-Mechnical stability thus relates to the aspect of

Hot strength, the strength of the after pyrolysis of the compacts in one

High-temperature zone remains residual semi-coke or coke particles. Thermo-mechanical stability refers to a test method in which the compacts are subjected to a thermal shock procedure, and the resulting semi-coke is subjected to drumming. The improved thermo-mechanical stability is represented by the fact that the proportion of coarse grain of the tumbled Halbkokses compared to conventionally produced compacts by the inventive

Impregnation is increased.

With a fixed bed packed from pyrolysis-derived semicarbons packed in accordance with the invention, a significantly better gas permeability and a better drainage behavior of the fixed bed are made possible than in the prior art. The improvement in the reactivity of the semi-coke therefore makes it possible to reduce or even avoid coke addition to COREX® or FINEX® feed coal

In the field of coking technology, the quality of the coke produced therefrom is known to be improved by increasing the bulk density of the feed coal. The use of many carburets for the production of metallurgical coke is even possible by a compression of the feed coal. In addition to stamped coking plants were therefore

Developed process variants for coking plants in bulk operation, which provided a briquetting or partial briquetting of the carburetor. From today's perspective, however, a briquetting with bituminous binder for economic reasons, a

Hot briquetting or briquetting with coal tar-based binder for reasons of health protection, and briquetting with molasses or comparable binders because of the entry of undesirable substances in the coke problematic.

The inventive method for the production of compacts makes it possible to reduce the consumption of binder or to curb the harmful effects of reactant-promoting binder components even in the production of coke using compacts of the starting materials.

The compacts may be, for example, briquettes or slugs from a compaction.

The pellets contain up to 97% by weight of carbon particles,

and up to 15% by weight of components of a binder system,

and, based on the weight of the material to be processed to compacts

Carbon particles, water-insoluble and / or water-repellent substances, or solids with water-repellent properties, in an amount whose lower limit

0.5% by weight, preferably 1% by weight, and the upper limit thereof is 5% by weight, preferably 3% by weight, particularly preferably 2% by weight

The 15% by weight of the components of a binder system are to be understood as meaning that the water is not included as a component of the binder system, ie the 15% by weight relates to the nonaqueous components of the binder

Binder system.

According to one embodiment, the compact also contains iron or iron oxide-containing particles. Such particles can, for example, in the pig iron or

Steel production incurred dusts or sludges.

Description of embodiments

Table 1 shows the evaluation of tests for the production of compacts with regard to the drop resistance (SF) and the puncture strength (PDF) of the pellets during a test campaign. The pellets are after the

inventive method with impregnation of a subset of the carbon particles with two impregnation steps, or produced with an impregnation step. The compacts are briquettes.

As the water-containing binder system, a system consisting of molasses and quicklime was used. The molasses itself had a water content of 20

% By mass.

The following commercially available molasses was used in the binder system:

Sugar cane molasses from Täte & Lyle with a total sugar content of 51%. As burnt lime in the binder system burnt lime white fine lime from Walhalla Kalk was used.

For impregnation bitumen and commercial hydraulic oil was used as

Impregnating agent used. As bitumen Mexphalte 55 Shell was used. The commercial hydraulic oil used was less viscous than the bitumen under the conditions of use.

The admixture of the impregnating agent bitumen was carried out in a Pfugscharmischer the company Lödige type FM130D, the other mixtures were in a

Batch mixer type R08 W manufactured by Eirich. The kneading machine from Köppern used for kneading purposes consisted of a vertical cylindrical container, through which a centrally rotating shaft with kneading arms is guided.

The production of the green compacts was carried out by means of a trial roller press type 52/10 from Köppern. The chosen pillow-shaped format for the

Green compacts had a nominal volume of 20 cm ³ . The task of the material to be pressed was done by means of gravitational arbiter. From the experimental roller press associations were made consisting of several green compacts. These associations contain green compacts both in the margins of the associations and in the middle of the associations.

In order to obtain individual green compacts or individual compacts for determining the fall resistance or the point compressive strength, the bandages are broken along the dividing seams between the individual green compacts. As a rule, the associations break up during discharge from the trial roller press into individual green compacts. After kneading in the kneader, the kneaded mixtures were subjected to pressing as a material to be pressed in the trial roll press to produce green compacts.

The resulting green compacts are still soft - which is indicated in the jargon by the word "green" - and are subjected to curing to arrive at the finished compact This curing, for example, by at least partial drying by storage in air and / or a thermal treatment done.

After pressing, individual green compacts were examined immediately, in the jargon green, for drop resistance (SF) and puncture resistance (PDF). The results of these studies are shown in the "immediate" columns for PDF and SF.

Fall and dot compressive strength measurements were repeated after 1 hour of air curing and after 24 hours air hardening. The results of these studies are shown in the columns containing "1 h" and "24 h".

In the fall test (based on ASTM D440) to determine the fall resistance, a 2 kg sample of green compacts or compressed by drying in air or by thermal drying compacts four times through a downpipe from a height of 5 m into a container, the bottom is formed in the form of a solid steel plate. The drop tube has a diameter of 200 mm and the collecting container has a diameter of 260 mm. The thickness of the steel plate is 12 mm. The evaluation of the fall test by sieve analysis takes place after the second and fourth fall. The numerical values for falling resistance SF in Table 1 indicate in each case the fraction of the grain fraction> 20 mm after four falls.

For the determination of the dot compressive strength, a type 469 testing machine from ERICHSEN was used. In this test method individual green compacts or hardened by drying in air or by thermal drying compacts clamped between two conditions, of which the lower is coupled to a load cell and the upper is continuously tracked by spindle drive for applying a creeping swelling pressure load. The lower edition is formed by a round plate of 80 mm diameter and the upper by a horizontal round iron of 10 mm diameter. The Feed rate for the upper support is 8 mm / min. The

Puncture resistance PDF is considered a maximum load bearing of a green

or a hardened compact registered before breakage - the entries in Table 1 indicate the average point compressive strength at break due to point pressure loading in Newton. In each case, six green compacts or compacts from the middle region and six green compacts or pellets from the edge region of the bandages obtained in the trial roller press were examined. From the data obtained in these studies, averages were calculated, with the minimum and maximum values, respectively, being disregarded. The

Mean values are given in Table 1.

Table 1

In experiment 1, a mixture was 70% by weight of Ensham coal with a medium

Particle size d50 of 0.95 mm together with 30% by weight of Ensham coal with a mean particle size d50 of 0.57 mm is used as material to be processed into pellets of carbon particles. This material to be processed into compacts was processed into compacts by impregnating by subjecting the coal to be processed to drying and then by granulation to a desired grain size. The resulting carbon particles are subjected to an impregnation step with the addition of bitumen. To the carbon particles thus obtained then takes place the addition of a water-containing binder system, in this case molasses with the addition of the solid, finely divided binder component quicklime, with mixing, wherein the mixing can be one or more stages. The resulting mixture is subjected to kneading and pressing. The product obtained after curing is the briquette.

Ensham coal comes from Ensham Resources of Queensland, Australia. The molasses in the water-containing binder system was used in an amount of 8% by weight, based on the weight of the material to be processed into compacts. The molasses itself contained a proportion of 20% by weight of water. In addition to molasses, the water-containing binder system consisted of 2% by weight, based on the weight of the material to be processed into compacts, Ensham coal, of burnt lime.

Dot crush strength and crash resistance at different times are given in Table 1, first data column.

In experiment 2 by the process according to the invention, the same material to be processed into compacts was used. The entire Ensham coal used was impregnated with commercial hydraulic oil and allowed to rest overnight. The amount of oil used was 2% by weight based on the weight of Ensham coal to be processed into compacts. Then the entire Ensham coal already impregnated with oil was impregnated with bitumen. As bitumen was shell

Mexphalte 50/70 with a softening point of about 50 ° C used. The amount of bitumen used was 2% by weight, based on the weight of the material to be processed into compacts. After impregnation with bitumen, the processing was carried out analogously to experiment 1 after its only impregnation step. The temperature of the coal treated with oil and bitumen was 53 ° C before the molasses addition.

It can be seen that a two-stage impregnation results in compacts having higher resistance to impact compared to compacts produced by a single-stage impregnation and having a higher puncture resistance after 24 hours.

One part can also be impregnated with one part in 2 or more stages, while the other part is not impregnated or only impregnated in one stage.

Brief description of the drawings

The method according to the invention is outlined below with reference to the block diagrams shown in FIGS. 1 to 3. According to FIG. 1, the coal 1 to be processed into compacts, in this case briquettes, is subjected to drying 2 and then brought to a desired grain size by granulation 3. The carbon particles 4 thus obtained are then subjected to a first impregnation step 6 with the addition of a first impregnating agent 5. The product 7 of the first impregnation step 6 is subjected to a second impregnation step 8 with a second impregnation agent 9. To the product 10 of the second impregnation step 8 then takes place the addition of a water-containing

Binder system 1 1, in this case molasses with the addition of solid, finely divided

Quicklime binder components, with mixing 12, wherein the mixing 12 may be one or more stages. The mixture 13 thus obtained is subjected to kneading 14 and then to pressing 15. The product 17 obtained after curing 16 is the briquette. Generally, in the production of compacts according to the present invention, the addition of the molasses / quicklime binder system to the product to be processed can be done by adding molasses and quicklime at the same time, or by adding quicklime and molasses in succession.

It is preferred in the use of impregnating agents such as bitumen, that at first a subset of the for the production of the compacts

provided molasses is added, then a mixture takes place, and then

Quicklime is added. After the resulting mixture has been allowed to stand, the remainder of the molasses intended for the preparation of the compacts is added. Subset and residual amount in total provide the intended for the production of the pellets molasses. The advantage of this approach is that one

Kneading the quicklime in soft impregnating agent during mixing of the material to be processed to compacts with the water-containing binder system is avoided or reduced.

In the case of impregnation, it may happen that for the quenching reaction of

Branntkalkes necessary moisture is not sufficiently available - in non-impregnated coals, this moisture can be removed from the lime from the coal particles. In this case it is necessary to use the impregnated coals

Moisten moisture. This can be done with water or part of the aqueous molasses done the binder system. For this purpose, up to half, preferably up to one third of the molasses can be used.

LIST OF REFERENCE NUMBERS

1 coal

2 drying

3 grains

4 carbon particles

5 first impregnant

6 first impregnation step

7 product of the first impregnation step

8 second impregnation step

9 second impregnant

10 product of the second impregnation step

1 1 water-containing binder system

12 mixing

13 mixture

14 kneading

15 pressing

16 hardships

17 product obtained after curing

List of quotations

patent literature

WO02 / 50219A1 WO9901583A1 AT005765U1

Claims

claims

1) A process for producing a carbon particle-containing compact, in which the carbon particles are mixed with a water-containing binder system and the resulting mixture is further processed by pressing into compacts, characterized

that before mixing with the water-containing binder system

at least a subset of the carbon particles is subjected to at least two impregnation steps in which it is impregnated with at least one substance.

2) Method according to claim 1, characterized in that an impregnation step of vapor deposition of the carbon particles with the substance, from spraying the coal particles with the substance, by mixing the substance into a moving bed of

Carbon particles, or by mixing the substance in a fluidized bed of carbon particles is.

3) Method according to one of the preceding claims, characterized in that the substance, are impregnated with the carbon particles, water. 4) Method according to one of claims 1-2, characterized in that the

Substance with which carbon particles are impregnated is a water-insoluble and / or water-repellent substance.

5) Method according to one of claims 1-2, characterized in that the

Substance with which carbon particles are impregnated is an aqueous solution of a substance or a mixture of substances.

6) Method according to one of claims 1-2, characterized in that the

Substance, are impregnated with the carbon particles, an aqueous suspension of solid colloids, wherein the solid has water-repellent properties is.

7) Method according to one of claims 1-2, characterized in that the

Substance with which carbon particles are impregnated, an emulsion containing on the one hand water and on the other hand carbonaceous substances, is. 8) Method according to one of the preceding claims, characterized in that the lower limit of the amount of added in the at least two impregnation steps substance 0.3% by weight, preferably 0.5% by weight, particularly preferably 1% by weight, and the upper limit. 5 % By weight, preferably 3% by weight, particularly preferably 2% by weight, based on the weight of the carbon particles to be processed into compacts.

9) Method according to one of the preceding claims, characterized in that the binder system contains molasses and quicklime or hydrated lime.

10) Method according to one of the preceding claims, characterized in that the binder system contains an emulsion of bitumen in water. 1 1) Method according to one of the preceding claims, characterized in that also iron or iron oxide-containing particles in a mixture with the

Coal particles are processed.

12) Method according to one of the preceding claims, characterized in that the compact is subjected to a heat treatment after the pressing.

13) Method according to one of the preceding claims, characterized in that the carbon particles are subjected to a heat treatment after the impregnation step prior to mixing with the water-containing binder system.

14) compact containing up to 97% by weight of carbon particles and up to 15% by weight of components of a binder system,

characterized in that it contains, based on the weight of the material to be processed pellets carbon particles, water-insoluble and / or water-repellent substances, or solids having water-repellent properties, in an amount whose lower limit is 0.5% by weight, preferably 1% by weight , and whose upper limit is 5% by weight, preferably 3% by weight, particularly preferably 2% by weight 15) compact according to claim 14, characterized in that the water-insoluble and / or water-repellent substance belongs to the group consisting of waxes, organic coking or refinery products, and plastics or waste plastics, and waste oil group of substances.

16) compact according to one of claims 14 and 15, characterized in that the compact also contains iron or iron oxide-containing particles.

17) Use of a compact according to one of claims 14 to 16

in a process for the production of pig iron in a fixed bed as carbon carrier or in a process for the production of carbon carriers for a process for

Pig iron production in a fixed bed.