RU2583432C2 - Method of manufacturing moulded articles containing coal particles - Google Patents

Abstract

FIELD: building industry.

SUBSTANCE: invention describes the method of manufacturing moulded articles comprising coal particles, in which the coal particles are mixed with a water-containing binder system, and the resulting mixture is processed by moulding to obtain the moulded articles, characterised in that before mixing with the water-containing binder system a partial amount of the coal particles are subjected to the impregnation stage at which the particles are impregnated with a substance. The said substance is added in the form of a liquid or using the liquid for impregnation, where the said substance is selected from the group consisting of water-insoluble and/or water repellent substances, aqueous colloidal suspension of a solid material. The solid material has water-repellent properties, and the lower limit of the amount of the said substance added at the stage of impregnation is 0.3 wt % relative to the weight of the coal particles of the material to be reprocessed into the moulding articles. Also the moulded article and its use in the process of iron smelting are disclosed.

EFFECT: obtaining moulding articles with sufficient strength.

13 cl, 3 dwg, 1 tbl

Description

Technical field

The invention relates to a method for manufacturing extruded articles containing coal particles, thus obtained extruded products, as well as the use of extruded products, in methods of smelting cast iron in a stationary layer or in methods for manufacturing carbon carriers for methods of smelting cast iron in a stationary layer.

State of the art

Used in the methods of smelting cast iron in a stationary layer, for example, in melting gasifiers or in the methods for producing carbon carriers for methods of smelting cast iron in a stationary layer, for example, production of coke for blast furnaces, pressed articles containing coal particles, for example, briquettes, should after exiting The press has a certain strength when dropped and compressive strength. Dumping strength is required so that the initial size of the pressed products during loading into the process, despite the inevitable dumping, for example, when transferring from one conveyor to another or when loading into a material hopper, remains essentially the same as possible. Compressive strength is required so that the initial value of the pressed products after loading into the material hopper or into a reactor with a stationary layer, despite the pressure produced by the overlying layers of the material, remains unchanged. These strength requirements are also collectively defined by the term “cold strength”.

Along with strength in the cold state, also the strength in the hot state of pressed products - especially when used in thermal processes - is a criterion for their suitability for use. In the special case of the use of pressed articles containing fine-grained particles of coal in a method of smelting cast iron in a stationary layer, such as, for example, in a melting gasifier or blast furnace, the term “hot strength” refers to a) the strength of the pressed articles remaining after pyrolysis in high temperature the area of the semicoke or coke particles; and b) the strength of these semicoke or coke particles, after the subsequent chemical exposure to the hot CO ₂ -containing gas. The minimum degree of strength in the hot state makes it possible that the particle size of the semi-coke or coke present after the conversion of the extruded products by pyrolysis, is essentially preserved. Therefore, in the method of smelting cast iron in a stationary layer, the formation of a fine fraction from pressed articles or coke particles before loading into the stationary layer or inside the stationary layer is undesirable, because the permeability of the stationary layer is thereby deteriorated. In a special case of the method of smelting cast iron in a stationary layer, this applies to both gas permeability and the drainage mode of the stationary layer with respect to molten iron and slag. If the permeability of the stationary layer worsens, then negative effects on its productivity, its specific energy consumption and its product quality should be expected.

From WO 02/50219 A1 it is known to manufacture pressed articles with sufficient cold strength from fine-grained particles of coal by means of a binder system from quicklime and molasses (molasses). At the same time, fine-grained particles of coal and quicklime are mixed, and the mixture, in order to continue the quenching reaction with moisture from the coal particles, remains at rest, then molasses is mixed, which plasticizes the resulting mixture, and finally, pressed articles are pressed from it.

There are coals that exhibit a very high ability to absorb water, in particular are characterized by high inherent humidity. However, for use in the smelting of pig iron, the humidity of the pressed products should not be too high, that is, lie at a maximum of 7%. This is explained by the fact that this moisture, when using pressed articles for smelting cast iron or for manufacturing carbon carriers for methods for smelting cast iron, acts as an energy load, since the specific consumption of carbon carriers increases markedly with increasing moisture in the pressed articles. Therefore, coals with a higher moisture content must be dried before being processed into pressed products. In addition to the non-wetted pore volume already existing in the non-dried coal, an additional pore volume is formed due to the removal of water from the cavities during drying. Unwetted pore volume can absorb an appropriate amount of water or an aqueous medium. Also, the additional pore volume can, of course, reabsorb water or an aqueous medium. In addition, certain coals also tend to - especially during intensive drying - form an additional pore volume due to damage to the grains. When drying coal with a high ability to absorb water to an acceptable humidity, a large additional pore volume is created before applying the method for manufacturing pressed articles described in WO 02/50219 A1. Therefore, the dried coal particle absorbs a significant part of the molasses necessary for binding on the surface of the particles, which should be understood as an aqueous solution. Therefore, for such coals with commonly used molasses additives in an amount of ≤10 wt.% (Weight%) with respect to the weight of the processed coal, it is impossible to achieve sufficient strength for pressed products. However, in order to still be able to produce pressed products with sufficient strength on the basis of molasses as a binder, it is necessary

- refuse to create an unimpaired pore volume by drying or

- add as much molasses as absorbed by the pore volume and therefore is not available for bonding coal particles on the surface.

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

Also, in the case of coals that are less moist by nature, which must not be dried in order to achieve a moisture content of the pressed articles, maximum 7 wt.%, Part of the molasses is absorbed into the pores of the coal particles. However, molasses contains components that act catalytically in relation to the reaction of carbon with hot CO ₂ -containing gases, which is why, in particular, in the hot zones of the stationary layer used for making cast iron at temperatures> 800-1000 ° С, depending on pressure, the degree of conversion of solid carbon with CO ₂ , according to the Bodo reaction, increases. As a result, the hot strength of the semi-coke or coke particles obtained from molded molded molded articles by pyrolysis is reduced.

The use of bitumen as a binder proposed in WO 9901583 A1 does not overcome such problems associated with the use of molasses. The manufacture of pressed products with bitumen is burdened, however, by the very high cost of the binder.

The use of an aqueous emulsion of bitumen as a binder system in AT 005765 U1 reduces the consumption of bitumen by more than 50%. However, in practice it turned out that the coke charge should have a moisture content significantly higher than 5 wt.%, So that when using such bitumen emulsions, stable pressed products are obtained. In addition, there is a problem in that the pores present in the coal particles can suck up an aqueous bitumen emulsion or remove water from the emulsion and thereby destabilize the latter, due to the coalescence of the droplets, before the substantially uniform distribution of the emulsion inside the processed into pressed articles can occur material and, accordingly, uniform wetting of the surface of the particles with an emulsion. Thus, the effectiveness of the emulsion as a binder is reduced.

SUMMARY OF THE INVENTION

Technical challenge

An object of the present invention is to provide a method for manufacturing extruded products, in which these disadvantages of the prior art are overcome and extruded products can be manufactured with sufficient strength in the dry state and hot condition even when using coal particles that must be pre-dried using a binder system containing less water in comparison with known methods.

Technical solution

This problem is solved by a method of manufacturing extruded products containing coal particles, in which the coal particles are mixed with a water-containing binder system, and the resulting mixture is then processed by pressing to obtain extruded products,

characterized in

that before mixing with a binder system containing water, a partial amount of coal particles is subjected to the stage of impregnation (impregnation), at which it is impregnated with a substance.

Preferred Effect of the Invention

When impregnated, the substance penetrates into the pores of the coal particles and prevents, respectively, by filling the pore space, the penetration of the components of the aqueous binder system. Or, the substance precipitates at the exit points of the pores on the surface of the coal particles, also called the neck of the pores, and prevents, through such blocking of the neck of the pores, the penetration of the components of the aqueous binder system into the pores.

In this way, it is prevented that the aqueous binder system, which is necessary on the surface of the coal particles in order to bind, will no longer be able to fulfill this binding goal after penetration into the pores. Accordingly, compared with the method in which the aqueous binder system can penetrate the pores, the mass of the desired aqueous binder system is reduced.

Preferably, the coal particles processed into pressed articles, or at least a partial amount thereof, are dried prior to the impregnation step to a moisture content of less than 8% by weight, preferably to a moisture content of less than 7% by weight. Humidity in the range of greater than / equal to 4 wt.% To less than 8 wt.% Is particularly preferred; humidity in the range of greater than / equal to 5 wt.% To less than 7 wt.% Is particularly preferred.

The aqueous binder system may, in addition to water, contain one or more other components.

The impregnation step may include applying by vaporization of the substance to the coal particles, irrigation of the coal particles by the substance, mixing the substance into a moving bed of coal particles, or mixing the substance into a vortex layer of coal particles.

A partial amount of coal particles that are subjected to an impregnation step before being mixed with a water-containing binder system, and coal particles that do not undergo an impregnation step may be the same material as for the type of coal and the average particle size. According to another embodiment, the partial amount of coal particles that are subjected to the impregnation stage before mixing with the water-containing binder system may be the same kind of coal as the coal particles that do not undergo the impregnation stage but have different average particle sizes than coal particles, which do not subject the impregnation step.

Not all coal particles processed into pressed articles are subjected to impregnation, but only a partial amount.

According to another embodiment, the partial amount of coal particles that are subjected to the impregnation stage before mixing with the water-containing binder system may be a different type of coal than coal particles that do not undergo an impregnation stage. In this case, the partial amount of coal particles to be impregnated and the non-impregnated coal particles may have the same or different average particle sizes.

If the partial amounts of coal particles from which the pressed articles are to be made are different in that they belong to different grades of coal, and from different grades of coal, pressed articles with different values for cold hardness or hot hardness would be obtained, then it is preferable to impregnate the partial amount from which pressed articles would be obtained with more unfavorable values for cold hardness or hot hardness .

If the coal particles from which the pressed articles are to be made belong to a single type of coal, but differ in that they have different average particle sizes, it may be preferable to impregnate, then a partial amount that has the maximum possible average particle size. Since the specific surface area for coal particles with a large average particle size is smaller than for coal particles with a smaller average particle size, in this way, for a given amount of impregnation agent, a greater part of the mass of coal particles processed into pressed articles can be impregnated than when impregnated with particles coal with a smaller average particle size.

If the coal particles from which the pressed articles are to be made belong to a single type of coal, but differ in that they have different average particle sizes, it may also be preferable to impregnate, then a partial amount that has the smallest possible average particle size. Since the specific surface for coal particles with a large average particle size is smaller than for coal particles with a smaller average particle size, for a given part of the mass to be impregnated, more surface is impregnated than when using a partial amount with a larger average particle size. This has the advantage that, for example, reactions with hot CO ₂ -containing gas that occur on the surface of the coal particles are more affected by the impregnation, since more surface is impregnated.

If the partial amount of coal particles from which the pressed articles are to be made has a negative effect on cold hardness or hot hardness compared to pressed articles that are made without this partial amount, it is preferable to impregnate this partial amount. In this way, one can reduce its negative effect on the properties of extruded products.

After the step of impregnating a partial amount of coal particles according to the invention has been performed, the impregnated partial amount of coal particles is combined with impregnated particles of coal, and the combined particles of coal are then processed into pressed articles.

The combination of the impregnated partial amount of coal particles with the non-impregnated particles of coal can be carried out at the stage of Association, in which only the Association and, if necessary, mixing. In this case, further steps are carried out for the manufacture of extruded products, namely, mixing the water-containing binder system with the product of association. The combination of the impregnated partial amount of coal particles with the non-impregnated coal particles can also be carried out during mixing with the water-containing binder system.

The substance to be impregnated is preferably administered as a liquid or by means of an impregnating liquid. As a liquid, for example, substances are described which, at the temperature occurring in the impregnation step, are liquid. Impregnation by means of a liquid is characterized, for example, by impregnation with substances which, although under the conditions occurring at the impregnation stage, are not themselves liquid, but are emulsified or suspended in a liquid.

Compared to the use of solids, this improves or even only makes it possible to penetrate into the pores or clog the necks of the pores.

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

According to an embodiment, the substance by which a partial amount of coal particles is impregnated in the impregnation step is water.

Then, at the impregnation stage, water is absorbed into the pores, which consequently no longer show any tendency to absorb the components of the aqueous binder system supplied to the coal particles after the impregnation stage. As a result, components that are absorbed into the pores in existing methods and thereby become useless for bonding pressed articles now contribute to the bonding of pressed articles.

By limiting the proportion of water-saturated extruded articles in the feed mixture for the cast iron smelting process in combination with carbon carriers that have lower moisture content than these pressed articles, the use of water in the cast iron smelting process can be limited to an acceptable extent.

According to another embodiment, a substance with which a partial amount of coal particles is impregnated in the impregnation step is water-insoluble and / or water-repellent (hydrophobic).

If the pores at the stage of impregnation are filled with such a substance, and the pore walls are coated with such substances, this reduces the tendency of the pores to absorb components of the aqueous binder system. If the exit points of the pores are closed from such substances on the surface of the coal particles, then no components of the aqueous binder system can penetrate the pores. As a result of this, components that are still absorbed into the pores and thereby become useless for bonding the pressed articles contribute to the bonding of the pressed articles.

Water-insoluble and / or water-repellent substance preferably belongs to the group consisting of waxes, organic coke products or refined products, as well as plastics or plastic wastes. Used oil may also be used. Bitumen may also be used. These substances are usually available in large quantities and do not require high costs.

The impregnation step is preferably carried out at a temperature at which the water-insoluble and / or water-repellent substance is liquid, in particular viscous. Viscous in this sense are liquids whose viscosity is at least 1 Pa · s and maximum 100 Pa · s, for example 10 Pa · s. Under these conditions, the substance is distributed over the surface of the coal particles and penetrates into the places where the pores exit, but hardly inside the pores. Due to this, the consumption of water-insoluble and / or water-repellent substances in the impregnation stage is kept low. Preferably, the water-insoluble and / or water-repellent solidifies upon cooling at the exit points of the pores on the surface of the coal particles.

According to another embodiment, the substance by which a partial amount of coal particles is impregnated in the impregnation step is an aqueous solution of a material or mixture of materials. For example, it is molasses, which is an aqueous solution of carbohydrates and other natural substances. In principle, substances of any type can be used that improve the hot hardness and cold hardness of pressed articles, for example, starch or an alkaline solution of lignin from spent alkali in a pulp production process.

It is preferable to use solutions of materials or mixtures of substances which, through heat treatment and / or a chemical reaction, are converted into water-insoluble substances. Thus, it is achieved that the effects caused by these materials or mixtures of materials are not reduced by dissolving them in water or in a water-containing binder system and washing them out of pores.

According to another embodiment, the substance by which a partial amount of coal particles is impregnated in the impregnation step contains a suspension of solid colloids, the substance having water-repellent properties. Examples of this are suspensions of colloidal talc, graphite or waxes in water. If solid materials are deposited in the pores or in the necks of the pores, the penetration of water-containing binder systems, due to the high surface tension of water-repellent solids, is difficult.

According to another embodiment, the substance by which a partial amount of coal particles is impregnated in the impregnation step is an emulsion containing, on the one hand, water and, on the other hand, carbon-containing substances, such as bitumen, crude tar obtained from coal, resins, waxes, oils.

When such emulsions penetrate into the pores, carbon-containing substances are deposited in thin layers on the surface of the pores. During pyrolysis, carbon layers are formed from these thin layers. They reduce the reactivity of the extruded products with respect to hot CO ₂ -containing gases in comparison with the embodiment in which thin layers of the substance do not precipitate in the pores. This effect also occurs when the substance by which a partial amount of coal particles is impregnated at the impregnation stage is not an emulsion, for example, when the substance is bitumen.

The occurrence of this effect lies in the fact that the carbon layers arising from substances contain little or no substances that act catalytically with respect to the reaction with hot CO ₂ -containing gases. In contrast, coal particles or material to be processed into pressed articles contain catalytically active compounds, for example, iron or alkalis. Accordingly, the reactivity of a pressed product, the surface of which and the pores are coated with a carbon layer obtained from substances, is less than the reactivity of a pressed product without such a carbon layer.

When using coal particles, which require drying before being processed into pressed articles, for economic reasons, it is preferable to perform drying not substantially lower than a moisture content of 5 wt.%, That is, to a maximum of 4 wt.% Moisture. Due to this, the occurrence of an additional pore volume due to drying is limited, and accordingly, less material is absorbed by the pores in the impregnation step. Accordingly, less material is consumed in the impregnation step. In addition, drying requires less hardware and energy costs.

The lower limit of the amount of substance added in the impregnation step, called the impregnating agent, is 0.3% by weight, preferably 0.5% by weight, particularly preferably 1% by weight, the upper limit is 5% by weight, preferably 4% by weight , particularly preferably 2 wt.%, with respect to the partial amount of material to be impregnated to be processed into pressed articles, that is, to a partial amount of carbon particles. The addition of more than 5 wt.% Impregnation means is not economically feasible. With the addition of less than 0.3% by weight of the impregnation agent, the impregnation becomes ineffective.

According to an embodiment of the method according to the invention, the binder system contains molasses, as well as quicklime or calcium hydroxide. It may also consist of these components.

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

According to an embodiment of the method of the invention, the binder system comprises an emulsion of bitumen in water. It may also consist of such an emulsion.

According to other embodiments, the binder system comprises pulp waste products, starch, cellulose, beet pulp, pulp, wood pulp, or also long-chain polyelectrolytes, such as carboxymethyl cellulose.

Since binder systems containing quicklime or calcium hydroxide have the disadvantage that quicklime CaO and calcium hydroxide Ca (OH) ₂ increase the reactivity of pressed articles with respect to hot CO ₂ -containing gases based on catalytic efficiency, without quicklime or calcium hydroxide, they have the advantage that pressed articles with relatively low reactivity are provided.

According to the embodiment of the method according to the invention, also iron-containing or containing iron oxide particles in a mixture with coal particles are processed into pressed articles.

According to a particular embodiment of the method according to the invention, the pressed articles are subjected to heat treatment after pressing. Heat treatment is carried out at an elevated temperature compared to pressing. Heat treatment causes drying and / or hardening of pressed products. Heat treatment can be carried out at temperatures preferably ≥250 ° C and ≤350 ° C, in which irreversible chemical processes can transform the components of the binder. For example, water-soluble binder components can be converted to water-insoluble compounds.

Compounds arising from such transformations can contribute to the strength of the extruded products.

In the case of a binder system containing molasses, for example, molasses is converted by caramelization.

According to a particular embodiment of the method according to the invention, at least a partial amount of coal particles that have been subjected to an impregnation step is subjected to heat treatment after the impregnation step, before being mixed with the water-containing binder system.

Heat treatment may be carried out in that the impregnated partial amount is separately subjected to heat treatment, and after heat treatment is combined with the impregnated coal particles, or the combination of the impregnated partial amount with the impregnated coal particles is carried out before the heat treatment of the coal particles.

Heat treatment causes drying. For the case when there are solutions or emulsions in the pores, heat treatment additionally causes the thickening of solutions, suspensions or emulsions and, accordingly, the coating of the pore walls with dissolved, suspended or emulsified components. They can, in addition to the subsequently added aqueous binder system, contribute to increased strength in the hot state and strength in the cold state.

In addition, heat treatment can cause the transformation of the coating of the pore walls, which first occurs due to heat treatment, into water-insoluble compounds or compounds that reduce the reactivity of coal particles with respect to hot CO ₂ -containing gases. The maximum heat treatment temperature is limited by the pyrolysis of coal particles and is 350 ° C. The lower limit for the temperature during this heat treatment is 150 ° C.

If the same water-containing emulsion as that used as the water-containing binder system is used for impregnation, the amount added in the impregnation step is less than the amount of water-containing binder system added with subsequent mixing. For example, when using an emulsion of bitumen in water at the stage of impregnation and as a binder system, an additive of 2-3 wt.% Is carried out at the stage of impregnation, while 7-10 wt.% Is later added as a binder system.

The same is true when the same aqueous solution of a substance or mixture of substances is used for impregnation as that used as the water-containing binder system. For example, when using molasses at the impregnation stage and as a binder system, 3-5% wt.% Is added at the impregnation stage, while 6-8 wt.% Is added later as a binder system. The boundaries of these ranges are also included. In these cases, after the addition at the stage of impregnation, heat treatment is necessary so that the water as a carrier liquid is removed to such an extent that emulsified substances or dissolved materials are deposited in the pores or on the necks of the pores. Thus, a coating is applied to the pores, or the neck of the pores is clogged. In general, a smaller amount of a water-containing binder system is required for the manufacture of extruded articles than in the manufacture without an impregnation step.

After mixing with the water-containing binder system, the processing of the pressed articles can be carried out by known methods, for example, as described in WO 02 / 50219A1 or AT 005765 U1, or by any method suitable for treating coal particles with a water-containing binder system.

Carried out in accordance with the invention only after the stage of impregnation of a partial amount of coal particles with an insoluble in water and / or water-repellent substance, the addition of a water-containing binder system in the manufacture of pressed articles reduces the cost of implementing the method relative to known methods, for example, as described in WO 02/50219 A1 . Preventing the perception of water by coal during the manufacture of molded products with water-containing binder systems reduces, on the one hand, the specific consumption of coal in cast iron smelting processes in which pressed products or coke obtained from them are used, since less water from the binder system is contained in the pressed product, and accordingly less energy for its evaporation should be used. On the other hand, the need for subsequent drying of the extruded products, which occurs in known methods for manufacturing extruded products based on the perception of water from the binder system, is eliminated by the application of the method of the invention, or the drying costs are reduced, which saves energy. Since, accordingly, you can refuse to create or operate devices for subsequent drying, or the size of these devices and the costs of their operation can be reduced, this is equivalent to a reduction in operating costs, as well as investment costs.

As an additional preferred effect of the impregnation step, depending on the type of substance used for impregnation, a decrease in the reactivity of the CO ₂ semicoke resulting from the pyrolysis of the pressed articles in the melting gasifier or obtained from the pressed coke articles may take place. A lower reactivity of CO _{2 is} desirable during the operation of the melting gasifier, so that the semi-coke in the stationary layer of the melting gasifier or coke in the stationary layer of the blast furnace from loading to the layer surface until the immediate gasification zone in the region of oxygen nozzles or tuyeres remains stable and thereby contribute to the permeability of the stationary layer regarding gas permeability and drainage of molten liquid phases. The decrease in the reactivity of CO _{2 of} semicoke or coke is achieved by the fact that the inner pore surface of the coal particles obtained from the impregnated partial amount of coal particles in the pressed product can no longer be coated with a binder, which contains substances that promote reactivity. For example, the component of the binder molasses contains alkali as substances promoting reactivity. If, by impregnation with, for example, substances containing bitumen or wax, the possibility that molasses will cover the inner surface of the pores is excluded, the reactivity of CO ₂ with respect to the semicoke or coke obtained by the method without an impregnation step is reduced.

A smaller portion of the fine-grained coke in the COREX® or FINEX® method for smelting cast iron in a stationary layer of a melting gasifier is often added to a coke charge to improve the permeability of the stationary layer. When using pressed articles made according to the method according to the invention, or from such a made coke, the decrease in the strength of the semi-coke or coke particles by means of hot CO _{2 is} slowed down and thus, the destruction of particles is prevented. In the case of extruded products made according to the invention, the improved thermomechanical stability of the semi-coke with respect to extruded products made in the usual way is also realized. Thermomechanical stability refers to the aspect of hot hardness, which relates to the hardness of the semi-coke or coke particles remaining in the high temperature zone after pyrolysis of the pressed products. Thermomechanical stability refers to the test method, in which the pressed products are subjected to a heat stroke procedure, and the resulting semi-coke is subjected to a drum test. Improved thermomechanical stability is ensured by the fact that the proportion of coarse grain of the semi-coke tested in the drum due to the impregnation according to the invention is increased in comparison with extruded products made in the usual way.

Using a stationary layer sealed with semi-coke obtained by pyrolysis from extruded articles made according to the invention, it is possible to noticeably better gas permeability and better drainage of the stationary layer than according to the prior art. Therefore, improving the properties of the reactivity of semi-coke makes it possible to reduce or even eliminate the addition of coke to the coke charge according to the COREX® or FINEX® methods.

In the field of coking technology, it is known that by increasing the density of the charge of the coke charge, the quality of the coke obtained from it improves. The use of many backfill coke charge to obtain blast furnace coke is generally only possible by compaction of the coke charge. Therefore, along with coke shops with tamping of loaded coal, variants of methods for coking in the filling mode have been developed, which include briquetting or partial briquetting of the coke charge. However, from a modern point of view, briquetting with a bitumen binder, for economic reasons, hot briquetting or briquetting with a binder based on coal tar, for health reasons, and briquetting with molasses or comparable binders, due to the introduction of undesirable materials into the coke, are problematic.

According to the invention, the method for manufacturing pressed articles provides the possibility that, in the manufacture of coke using pressed articles of filled materials, the consumption of a binder is reduced or the harmful effects of the reactive components of the binder are limited.

Pressed articles may be briquettes or potholes from briquetting.

Pressed articles contain up to 97 wt.% Of coal particles and up to 15 wt.% Of the components of the binder system, as well as, in relation to the weight of the material of coal particles processed into pressed articles, insoluble in water and / or water-repellent substances or solids with water-repellent properties in an amount whose lower limit is 0.5 wt.%, preferably 1 wt.%, and the upper limit of which is 5 wt.%, preferably 3 wt.%, particularly preferably 2 wt.%.

Moreover, 15 wt.% Of the components of the binder system should be understood in such a way that water is not included as a component of the binder system - 15 wt.% Relate, therefore, to non-aqueous components of the binder system.

According to an embodiment, the pressed article also contains particles containing iron or iron oxide. Such particles may, for example, come from dust or sludge arising from the smelting of iron or steel.

Description of execution forms

Table 1 shows the evaluation of the pressed fabrication tests with respect to dropping strength (SF) and the point compressive strength (PDF) of the molded products as part of the test. In this case, the pressed articles were made according to the invention according to the method by impregnating a partial amount of coal particles.

According to the prior art, pressed articles were made in such a way that all the coal particles were impregnated with water - with the addition of 3 wt.% Water for a minute.

Pressed articles are briquettes.

The strength when dropping raw pressed products and finished pressed products made in accordance with the invention, as well as raw pressed products and finished pressed products made according to the prior art — with correspondingly the same materials being filled in using 12% by weight of molasses and under otherwise identical conditions — have the same order of magnitude, both for raw pressed products, and for pressed products, dried in air or dried thermally.

As a water-containing binder system, a system consisting of molasses and quicklime was used. Molasses itself had a water content of 20% by weight. The following commercially available molasses was used in the binder system: sugar cane molasses from Tate & Lyle with a total sugar content of 51%. Quicklime in the binder system used quicklime such as white ground lime from Walhalla Kalk.

Bitumen was used as an impregnating agent for impregnation. Shell was used as bitumen Mexphalte 55.

Mixing of the impregnating substance in the form of bitumen was carried out in a mixer with ploughshare blades of the Lödige company type FM130D, the rest of the mixtures were prepared in a batch mixer type R08W of the company Erich.

The Koeppern mixer used for the kneading process consisted of a perpendicularly oriented cylindrical tank through which a rotating shaft with kneading levers was held in the center.

Raw pressed products were manufactured using a Koeppern type 52/10 test roller press. The selected pillow shape for raw pressed products had a nominal volume of 20 cm ³ . The supply of the pressed material was carried out by means of a gravitational batcher. At the same time, through the test roller press, structures (bundles) were made from a variety of crude extruded products. In these ligaments, raw pressed products are found both in the marginal region of the ligaments and in the middle region of the ligaments.

In order to obtain discrete compressive strength and compressive strength, to obtain individual raw extruded products or individual extruded products, the ligaments were broken along the dividing seams between the individual raw extruded products. As a rule, the ligaments were broken when they were withdrawn from the test roll press into individual raw pressed products.

After the kneading process in the mixer, the plasticized mixtures were pressed as a press material in a test roll press to obtain crude pressed products.

The raw pressed products obtained in this way are still soft - which is indicated by the term “grün” (“green”, “immature”) in professional jargon - and are cured to obtain a finished pressed product. This curing can be carried out, for example, at least in part, by storage in air and / or by heat treatment.

After extrusion, individual raw extruded products are directly, that is, fresh, examined for drop strength (SF) and point compressive strength (PDF). The results of these studies are shown in the “immediately” columns for SF and PDF. The drop strength and pressure compression strength measurements were repeated after 1 hour of curing in air and 24 hours of curing in air, respectively. The results of these studies are shown in the columns “1 hour” and “24 hours”.

In a dropping test (based on ASTM D440), to determine the dropping strength, a sample weighing 2 kg of raw pressed products or cured by air drying or by thermal drying of the pressed products was repeatedly dropped through a downpipe from a height of 5 m into a receiving tank, the bottom of which is made in the form of a massive steel plate. The drain pipe has a diameter of 200 mm, and the collection tank has a diameter of 260 mm. The thickness of the steel plate is 12 mm. The drop test evaluation was carried out by means of a sieve analysis (grain analysis) after the second and fourth drop. The numerical values for SF drop strength in Table 1 indicate a particle size fraction> 20 mm after four drops.

To determine the compressive strength, a type 469 test rig from ERICHSEN was used. In this test method, individual wet pressed products or cured by drying in air or by thermal drying, the pressed products were clamped between two plates, of which the lower one is connected to a force sensor, and the upper one is continuously fed through a spindle transfer mechanism to apply a gradual pulsating pressure load. The lower plate is formed by a round plate with a diameter of 80 mm, and the upper one - by horizontal bar metal with a diameter of 10 mm. The feed rate for the top cover is 8 mm / min. Point compressive strength PDF is recorded as the maximum load perception of a raw or cured molded product before breaking — the entries in Table 1 indicate the average point compressive strength when breaking due to point compressive loading in Newtons. Six raw pressed products or pressed products from the middle region and six raw pressed products or pressed products from the edge region of the bundles obtained in the test roll press were respectively investigated. From the data obtained during these studies, average values were calculated, and accordingly the minimum and maximum values were not taken into account. Average values are given in table 1.

Table 1 Experience No. PDF [H] immediately PDF [H] 1 h PDF [H] 24 h SF immediately SF 1 h one 46 84 149 70 78 2 104 166 252 73 67

In experiment 1, according to the prior art, a mixture of 70 wt.% Ensham coal with an average particle size of d50 of 0.95 mm was used, together with 30 wt.% Blackwater coal with an average particle size of d50 of 0.8-1.0 mm, as particles of coal processed into pressed articles.

Blackwater coal is supplied by BHP Billiton of Queensland, Australia. Ensham coal is supplied by Ensham Resources of Queensland, Australia. This material processed into extruded products was processed, as shown further in FIG. 1, for coal 1 into extruded products. A binder system containing molasses in water was used in an amount of 12 wt.% With respect to the weight of the material processed into pressed products. The molasses used contained the fraction of water itself, equal to 20 wt.%. The water-containing binder system contained, along with molasses, still quicklime in the amount of 2.5 wt.% With respect to the weight of the material processed into pressed products. Point compression strength and dropping strength at various points in time are shown in Table 1, in the first data column.

In experiment 2, according to the method according to the invention, the same material processed into pressed articles was used. In general, the used Ensham coal was impregnated with bitumen. Shell bitumen A with a softening point of 85 ° C was used as bitumen. The amount of bitumen used was 2.1 wt.% With respect to the weight of the material processed into pressed products, or 3 wt.% With respect to the impregnated Ensham coal. The temperature of the coal was 108 ° C before mixing bitumen. After soaking, the impregnated Ensham charcoal combined with Blackwater charcoal. After combining them, processing followed similarly to experiment 1, but a binder system containing molasses in water was used in an amount of 8 wt.% With respect to the weight of the material processed into extruded products. The molasses used itself contained a proportion of water of 20 wt.%. The water-containing binder system contained, along with molasses, still quicklime in an amount of 2 wt.% With respect to the weight of the material processed into pressed products. After the addition of quicklime, another 2% of water was mixed with the weight of the material processed into pressed products in order to provide the moisture necessary for quicklime for its reaction.

You can see that the molded products made according to the method of the invention have a higher pressure strength compared to the prior art, while their dropping strength is comparable to the dropping strength of molded products made according to the prior art.

Partial amount of coal particles to be impregnated may also undergo two or more impregnation steps.

Brief Description of the Drawings

Next, the method according to the invention is described using the flowcharts shown in figures 1-3.

Figure 1 shows a conventional method for manufacturing extruded articles without an impregnation step.

Figure 2 shows a method according to the invention for manufacturing pressed articles with an impregnation step, two types of coal being used.

Figure 2 shows a method of manufacturing pressed articles with an impregnation step according to the invention, wherein only one grade of coal is used.

According to figure 1, the coal 1 to be processed into pressed products, in this case briquettes, is dried 2 and then, by crushing 3 is brought to the desired particle size distribution. Then, the binder system 4 containing water, in this case molasses, is added to the coal particles obtained with this, if necessary with the addition of solid, fine-grained components of the binder, such as calcium hydroxide or quicklime, by mixing 5, and mixing 5 can be carried out in one step or in several stages. The resulting mixture is subjected to kneading (plasticization) 6 and pressing 7. The product 9 obtained after curing (hardening) 8 is a briquette.

Corresponding to the invention, the method of FIG. 2 differs from the method shown in FIG. 1 in that a partial amount A of coal particles 12, used for the manufacture of pressed articles, is subjected to an impregnation step 10, in which they are impregnated with the substance 11, an impregnation means. After this impregnation step 10, a mixing step 5 is carried out with a binder system 4 containing water and with a partial amount B of coal particles 13, which are used for the manufacture of pressed articles, as well as further processing of the resulting mixture, respectively, of FIG. 1. The coal particles used for the manufacture of extruded products are thus made up of a partial amount of A 12 and a partial amount of B 13. A partial amount of A 12 and a partial amount of B 13 belong to different grades of coal.

In contrast to FIG. 2, partial quantities A 12 and B 13 of coal particles used for the manufacture of extruded products, according to FIG. 3, refer to the same kind of coal. The coal 1 to be processed is dried 2, and then, by crushing 3, it is brought to the desired particle size distribution. The resulting coal particles are sieved 14. The resulting coarse fraction as a partial amount A of coal particles 12, used for the manufacture of pressed products, undergoes an impregnation stage 10, in which it is impregnated with a substance 11, which serves as an impregnation means. After this impregnation step 10, 5 is mixed with a binder system 4 containing water, and with a partial amount B of coal particles 13, which are used for the manufacture of pressed articles, as well as further processing of the resulting mixture, respectively, of FIG. 1. Partial amount B of coal particles 13, used for the manufacture of extruded products, is obtained by sieving 14 fine-grained fraction.

After the impregnation step 10, heat treatment 12 may be performed before mixing with the binder system 4 containing water.

In general, in the manufacture of extruded products according to the proposed invention, the addition of a water-containing binder molasses / quicklime system to the material processed into extruded products is carried out in such a way that molasses and quicklime are added at the same time, or so that quicklime and molasses are added one after another.

Moreover, when using bitumen impregnation means, it is preferable that a partial amount of molasses provided for the manufacture of pressed articles is first added, then mixing is carried out, and then quicklime is added. After the mixture thus obtained was at rest, the residual amount of molasses provided for the manufacture of pressed articles is added. The aforementioned partial amount and residual amount add up to molasses provided for the manufacture of molded products. The advantage of this method of action is that the mixing of hydrated lime into a soft impregnation agent is eliminated or reduced while mixing the material processed into the pressed products with a water-containing binder system.

Due to the addition of molasses, which itself contains water, before adding quicklime, quicklime can also use moisture from molasses for its reaction.

You can add up to half, preferably up to one third, molasses before adding quicklime.

List of Reference Items

1 coal

2 Drying

3 Crushing

4 Water-containing binder system

5 Mix

6 Kneading

7 Pressing

8 curing

9 Product

10 Stage impregnation

11 Substance (means of soaking)

12 Partial amount A of coal particles for the manufacture of extruded products

13 Partial amount B of coal particles for the manufacture of extruded products

14 Screening.

Reference List

Patent Literature

WO 02/50219 A1

WO 9901583 A1

AT 005765 U1.

Claims (13)

1. A method of manufacturing extruded articles containing coal particles, in which the coal particles are mixed with a water-containing binder system, and the resulting mixture is processed by pressing to obtain extruded products,
characterized in that before mixing with a binder system containing water, a partial amount of coal particles is subjected to an impregnation step in which the particles are impregnated with a substance,
wherein said substance is administered in the form of a liquid or by means of a liquid for soaking,
wherein said substance is selected from the group consisting of water-insoluble and / or water-repellent substances, an aqueous suspension of colloids of solid material, wherein
solid material has water repellent properties;
however, the lower limit of the amount of the specified substance added at the stage of impregnation is 0.3 wt.% with respect to the weight of coal particles of the material to be processed into pressed products. 2. The method according to p. 1, characterized in that the stage of impregnation includes applying by evaporation of the substance on the particles of coal, irrigation of the substance of the particles of coal, mixing the substance into a mobile filling of coal particles or mixing the substance into a vortex layer of coal particles. 3. The method according to any one of paragraphs. 1 and 2, characterized in that the substance with which the particles of coal are impregnated at the stage of impregnation, is an emulsion containing, on the one hand, water, and also, on the other hand, carbon-containing substances. 4. The method according to any one of paragraphs. 1 and 2, characterized in that the upper limit of the amount of substance added in the impregnation step is 5 wt.%, Preferably 3 wt.%, Particularly preferably 2 wt.%, Relative to the weight of the coal particles of the material to be processed into pressed articles . 5. The method according to any one of paragraphs. 1 and 2, characterized in that the binder system contains molasses, as well as quicklime or calcium hydroxide. 6. The method according to any one of paragraphs. 1-2, characterized in that the binder system contains an emulsion of bitumen in water. 7. The method according to any one of paragraphs. 1 and 2, characterized in that also iron-containing or containing iron oxide particles in a mixture with coal particles are processed into pressed products. 8. The method according to any one of paragraphs. 1 and 2, characterized in that the pressed products after pressing are subjected to heat treatment. 9. The method according to any one of paragraphs. 1 and 2, characterized in that at least a partial amount of coal particles that are subjected to the impregnation stage, after the impregnation stage, is subjected to heat treatment before mixing with the water-containing binder system. 10. A molded product containing up to 97 wt.% Coal particles, and up to 15 wt.% Components of the binder system,
characterized in that it, in relation to the weight of the material of the coal particles to be processed into pressed products, contains water-insoluble and / or water-repellent substances or solids with water-repellent properties in an amount, the lower limit of which is 0.3 wt.%, preferably 0.5 wt.%, particularly preferably 1 wt.%, and whose upper limit is 5 wt.%, preferably 3 wt.%, particularly preferably 2 wt.%. 11. A molded product according to claim 10, characterized in that the water-insoluble and / or water-repellent substance belongs to the group of substances consisting of waxes, organic products of coke production or refining, as well as plastics or plastic and waste oil production wastes. 12. A molded product according to claim 10 or 11, characterized in that the molded product also contains particles containing iron or iron oxide. 13. The use of pressed products according to any one of paragraphs. 10-12 in the process of smelting cast iron with a stationary layer as carbon carriers or in the manufacturing process of carbon carriers for the process of smelting cast iron in a stationary layer.

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