WO2025003290A1 - Method for processing a residue mixture containing the elements iron and/or calcium, and corresponding processing plant - Google Patents

Abstract

The invention relates to a method for processing a residue mixture (12) containing the elements iron and/or calcium for industrial use by at least partially separating at least one volatile element, in particular a volatile element from the following list of elements: Zn, Pb, Na, K, Cl, S, F and P, from this residue mixture (12) in a furnace (14), wherein this residue mixture (12) is in the form of a granular residue mixture or at least comprises a granular fraction. According to the invention, the furnace (14) is designed as a rotary furnace or rotary kiln (16) and a process gas having a hydrogen fraction of more than 5 vol.%, in particular of more than 50 vol.%, is fed to the rotary furnace or rotating kiln (16) for the processing of the residue mixture (12). The invention further relates to a corresponding computer program product, which prompts a processor to carry out the method, and to a corresponding processing plant (10) for processing a residue mixture (12) containing the elements iron and/or calcium for industrial use.

Description

Process for the treatment of a residue mixture containing the elements iron and/or calcium and corresponding treatment plant

The invention is based on a method for processing a residue mixture containing the elements iron and/or calcium for industrial use by at least partially separating at least one volatile element, in particular the following list of elements: Zn, Pb, Na, K, CI, S, F and P, from this residue mixture in a furnace, wherein this residue mixture is designed as a granular residue mixture or at least has a granular portion.

The invention is further based on a corresponding computer program product for carrying out the method and a corresponding processing plant for processing a residue mixture containing the elements iron and/or calcium for industrial use, comprising a furnace for at least partially separating at least one volatile element, in particular the following list of elements: Zn, Pb, Na, K, CI, S, F and P, from this residue mixture, wherein this residue mixture is designed as a granular residue mixture or at least has a granular portion.

In the blast furnace, converter and rolling mill of an integrated steelworks, dusts/sludges with a high content of iron and/or calcium oxide are usually produced. Of these dusts/sludges, blast furnace dust and converter dust are at least partially recycled by adding them to the initial sinter mixture, and mill scale, which has a high iron content, serves mainly as an iron carrier in sinter production.

When blast furnace dust and converter dust are recycled in the steelworks in this way, unwanted metals such as zinc, lead and alkali metals accumulate, which limits the internal circulation of these materials. In particular, when blast furnace dust and converter dust are recycled by adding them to sinter, these unwanted metals accumulate in the blast furnace through the sinter, which leads, for example, to the formation of deposits on and in the furnace wall of the blast furnace, thereby reducing its performance and the duration of the furnace cycle.

The term “granular mixture” in connection with the present Invention is understood to mean a mixture of a large number of solid particles which in turn are heterogeneously permeated by an environmental medium, such as air or water, so that bulk material properties arise.

The document EP 2 458 021 A1 describes a processing plant for processing a residue mixture containing the element iron for use in the metallurgical industry, with a rotary hearth furnace for at least partially separating the volatile metal elements zinc (Zn), lead (Pb), sodium (Na) and/or potassium (K) and for reducing the element iron from the residue mixture, whereby this residue mixture for processing in the furnace is present as a granular residue mixture of carbon composite agglomerates that were previously created from ironworks dust and other components, at least one of which provides the carbon. The said document also describes a corresponding method for processing a residue mixture containing the element iron for use in the metallurgical industry. However, the additional step of agglomerating the ironworks dust with other components to form the carbon composite agglomerates alone results in increased expenditure.

It is an object of the invention to provide a method and a processing plant for processing a residue mixture containing the elements iron and/or calcium for industrial use, in particular in the metallurgical industry, by means of which the processing can be carried out particularly easily.

The object is achieved according to the invention by the features of the independent claims. Preferred embodiments of the invention are specified in the subclaims, which can each represent an aspect of the invention individually or in combination.

In the method according to the invention for processing a residue mixture containing the elements iron and/or calcium for industrial use by at least partially separating at least one volatile element from this residue mixture in a furnace in which this residue mixture is designed as a granular residue mixture or at least has a granular portion, it is provided that the furnace is designed as a drum or rotary kiln and a process gas with a hydrogen portion is fed to the furnace for processing the residue mixture of more than 5% by volume, in particular more than 50% by volume. In other words, a drum or rotary kiln with a hydrogen-containing atmosphere is used to process the residue mixture.

A drum furnace or rotary kiln (DRO) is a cylindrical furnace for process processes that usually rotates continuously around its own axis during operation. The rotary kiln often has a slight inclination of the axis of rotation, which together with the rotational movement ensures product or fuel transport.

It has been found that when using a drum furnace or a rotary kiln to process the waste mixture, the particle size of the individual particles of the granulate can be significantly smaller than with a rotary hearth furnace, so that a preparatory step of agglomerating waste particles in the form of dust particles or similar can be omitted. Handling such a drum furnace or rotary kiln is also much easier than that of a rotary hearth furnace. The hydrogen content in the atmosphere - especially in combination with a small particle size of the granulate particles - also enables a chemical reduction of chemical components of the granulate material, for example the element iron (Fe) in a waste mixture containing this element.

The volatile elements, at least one of which must be at least partially separated, are in particular the elements from the following list: Zn, Pb, Na, K, CI, S, F and P.

According to a preferred embodiment of the invention, the granular residue mixture or the granular portion of the residue mixture consists of particles whose particle size is 85% by weight smaller than 10 millimeters (10 mm).

Advantageously, more than 50% by weight, in particular more than 80% by weight, of the granular residue mixture or the granular portion of the residue mixture is in the form of dust and/or - preferably dried - sludge when it is filled into the drum or rotary kiln. The particle size of the particles of the dust and/or - preferably dried - sludge is in the micrometer range, i.e. less than 1.0 mm, preferably less than 400 pm. According to a further preferred embodiment of the invention, the residue mixture contains not only the elements iron and/or calcium but also the element carbon (C), preferably of biogenic origin. Carbon of biogenic origin comes from a renewable raw material and not from a fossil raw material, and therefore has no fossil origin.

Due to the carbon in the residue mixture, the atmosphere in the furnace is enriched with carbon monoxide (CO) during the processing of the residue mixture and preferably has a carbon monoxide content of more than 5% by volume. The carbon monoxide is formed by the reduction of water vapor produced in the process to carbon and thus reduces the hydrogen required for the process.

According to yet another preferred embodiment of the invention, the drum or rotary kiln is operated at a kiln temperature of 830 °C to 1030 °C, preferably 880 °C to 990 °C, during the processing of the residue mixture. This temperature range of the kiln temperature has proven to be advantageous both for the separation process and for an optional reduction process.

In particular, it is intended that the residue mixture is exposed to the furnace temperature in the drum or rotary kiln for a period of 15 minutes to 150 minutes during its processing in the furnace. Such a period of time, in combination with the furnace temperature mentioned, has proven to be advantageous both for the separation process and for an optional reduction process.

Preferably, it is further provided that when separating the at least one volatile element from the residue mixture, this at least one volatile element is discharged via the atmosphere/a gas phase in the drum or rotary kiln and separated in a filter device.

The invention further relates to a computer program product which comprises instructions which, when executed by a processor of a control and/or regulating device, cause this processor to carry out an above-mentioned method.

In the processing plant according to the invention for processing a the elements Iron and/or calcium-containing residue mixture for industrial use, which has a furnace for at least partially separating at least one volatile element from this residue mixture, wherein this residue mixture is designed as a granular residue mixture or at least has a granular portion, it is provided that the furnace is designed as a drum or rotary kiln and the processing plant comprises a device for supplying a process gas to the drum or rotary kiln, which has a hydrogen portion of more than 5% by volume, in particular of more than 50% by volume. The advantages mentioned in connection with the processing method according to the invention also arise here: omission of the agglomeration step, simple handling and the possibility of reducing components by means of hydrogen from the atmosphere in the furnace.

The volatile elements, at least one of which must be at least partially separated, are in particular the elements from the following list: Zn, Pb, Na, K, CI, S, F and P.

According to a preferred embodiment of the processing plant according to the invention, it is provided that the device for supplying the process gas comprises a dosing system for providing a selectable hydrogen content in the process gas.

According to a further preferred embodiment of the processing plant according to the invention, it has gas-tight components for using the process gas with a hydrogen content, at least one of which is a component of the device for feeding the process gas into the drum or rotary kiln. The gas-tightness referred to here also relates in particular to the hydrogen content, i.e. the H2 in the process gas.

The furnace preferably has a heating device for direct or indirect heating, via which a furnace temperature inside the furnace of up to 1030 °C can be achieved. By means of this heating device, the furnace is operated during the processing process at a furnace temperature of 830 °C to 1030 °C, preferably from 880 °C to 990 °C.

In particular, it is intended that the treatment plant shall have a control and/or

Control device for controlling or regulating the operation of the processing plant This preferably has a processor, i.e. is computer-based.

Furthermore, it is preferably provided that the processing plant has a gas outlet with a filter device for separating the at least one volatile element discharged via the atmosphere/a gas phase in the drum or rotary kiln.

Finally, it is advantageous that the treatment plant is explicitly designed to carry out the above-mentioned process.

The invention is explained below by way of example with reference to the attached drawing using a preferred embodiment, wherein the features shown below can represent an aspect of the invention both individually and in combination. They show:

Fig. 1 shows a processing plant for processing an iron- and/or calcium-containing residue mixture for industrial use according to a preferred embodiment of the invention.

Fig. 1 shows a processing plant 10 for processing a residual material mixture 12 containing iron and/or calcium for industrial use. The central unit of this processing plant 10 is a furnace 14 in the form of a drum or rotary kiln 16 for at least partially separating at least one volatile element from the following selection of elements: Zn, Pb, Na, K, CI, S, F and P from the said residual material mixture 12. In the following, the residual material mixture 12, which contains the elements iron and/or calcium, is referred to simply as residual material mixture 12.

The drum or rotary kiln 16 shown here is designed as a typical rotary kiln (DRO), i.e. as a kiln 14 with a rotary tube 20 that is rotatably mounted about its longitudinal axis 18, which is shown in section in the figure so that the interior of the rotary tube 20 with the residual material mixture 12 located therein is visible. This interior of the rotary tube 20 essentially forms the interior 22 of the drum or rotary kiln 16. The rotary tube 20 is rotatably mounted via bearings 24, whereby the kiln 16 also has a drive 26 for rotating the rotary tube 20 about the longitudinal axis 18. The rotary tube 20 can be heated directly or indirectly via a heating device (not shown) and serves to receive and circulate the residual material mixture 12 in its interior 22. A slight inclination (of a few degrees) of the longitudinal axis 18 relative to the horizontal determines the direction in which the residual material mixture 12 flows through the drum or rotary kiln 16 from an inlet 28 to an outlet 30 of the kiln 16 (arrow 32). At the outlet 30, the processed residual material mixture 12 leaves the drum or rotary kiln 16 and is transferred to a - preferably closed - container 34.

In addition to the drum or rotary kiln 16, the processing plant 10 also has a feed device 36 for feeding residual material mixture 12 into the kiln 16, a device 38 for feeding a process gas into the interior 22 of the kiln 16 and a control and/or regulating device 40 for controlling or regulating the operation of the processing plant 10. The feed device 36 for feeding residual material mixture 12 into the drum or rotary kiln 16 in turn comprises a storage container 42 for holding residual material mixture 12 and a conveyor device 44 with a conveyor screw (not shown), via which the residual material mixture 12 can be transported or is transported from the storage container 40 to the inlet 28 of the drum or rotary kiln 16. In this example, the device 38 for supplying a process gas comprises several gas storage units 46, 48 and a metering system 50 for metered supply of the gases from these gas storage units 46, 48 to the outlet 30 of the drum or rotary kiln 16. The gas storage units 46, 48 are representative examples of various gas sources. One of the gases is hydrogen (H2), another is, for example, methane (CH4) or ammonia (NH3). The hydrogen content of the process gas or the atmosphere in the interior 22 of the drum or rotary kiln 16 can be adjusted via the metering system 50 of the device 38. The control and/or regulating device 40 for controlling or regulating the operation of the processing plant 10 controls components 26, 44, 50 of the drum or rotary kiln 16, the feed device 36 and/or the device 38 for supplying the process gas.

In the example shown here, the drum or rotary kiln 16 is used in countercurrent operation, in which the residue mixture 12 and the gas inside 22 of the kiln 16 move in opposite directions through the kiln 16. At the inlet 28 there is therefore a gas outlet 52 with a filter device 54 in which the said volatile elements accumulate. As an alternative to the countercurrent operation shown here, a direct current operation with a corresponding structure can also be used. be provided.

The processing plant 10 and in particular its drum or rotary kiln 16 is now operated in such a way that at least one volatile chemical element, in particular at least one chemical element from the following list of elements: Zn, Pb, Na, K, CI, S, F and P, is at least partially separated from the residual material mixture 12. For this purpose, the drum or rotary kiln 16 is operated at a furnace temperature of 830 °C to 1030 °C, preferably 880 °C to 990 °C, during the processing of the residual material mixture 12 and it is ensured that the residence time of the residual material mixture 12 in the interior 22 of the drum or rotary kiln 16 at this furnace temperature is 15 minutes to 150 minutes. These parameters have proven to be particularly favorable for the separation of the said elements. An optional chemical reduction via the hydrogen in the atmosphere can also be easily implemented with these parameters. The process gas supplied by device 38 has a hydrogen content of at least 5% by volume.

In the following, given boundary conditions, possible applications, particularly favorable process parameters and possible advantages of the invention and its various embodiments will be described again in other words:

This creates the opportunity to recycle or utilize:

(a) iron-containing residues with a grain size preferably < 10 mm,

(b) calcareous residues with a grain size preferably < 10 mm,

(c) carbonaceous residues and in particular biochar with a grain size preferably < 10 mm,

- Utilisation of low-quality (bio-) C-carriers (high ash content, low C content of < 85% by weight),

- Utilisation of mill scale and other iron-containing materials, e.g. chips, preferably with a grain size < 10 mm, whereby the residual materials contain/can contain in particular the following accompanying elements (as chemical elements in various compounds):

Zn, Pb, Na, K, CI, F, Cu, P, Mn, V, Cr in the residue mixture 12.

Recycling of mostly contaminated dust and sludge and other fine-grained residues with a grain size preferably up to 10 mm with simultaneous at least partial removal of the undesirable accompanying elements Zn, Pb, Na, K, CI and F in the drum or rotary kiln 16 under an H2-containing atmosphere. Iron-containing feedstocks are reduced in the process and can then be briquetted for reuse in the steel industry, for example in the electric arc furnace, smelter, smelting reduction furnace (SAF: Submerged Arc Furnace) or converter.

The following advantages arise: economic utilization of Fe and/or Ca-containing residues from the steel industry and other industries,

Production of HBI (hot briquetted iron) or cold briquetted iron from waste materials,

Saving of primary raw materials and/or

Utilization of inferior (organic) C-carriers and

Recovery of Zn and Pb even with low initial contents in the feedstocks.

Other metals that are in the residual materials can also be reduced in the rotary kiln and thus possibly be used for subsequent recycling. The accompanying elements that are separated out via the gas phase can also be used in subsequent steps if necessary.

This results in a process for the utilization of various residual materials (in particular fine-grained dust, sludge and other residual materials), whereby a grain size of < 10 mm is preferred as the maximum grain size (larger grain sizes require longer process times and reduce economic efficiency). The drum or rotary kiln process under an H2-containing atmosphere enables the reduction of the iron content, the utilization of C-containing feedstocks (both fossil carbon (fossil C) and bio-carbon (bio-C) and, for example, paper and plastic components) and the extensive removal of K, CI, Zn, Pb, Na and optionally F from residual materials. This limits the enrichment of Zn, Pb, Na, K and CI in the circuit to a permissible level and the volatile substances can be enriched in the filter device 54 and then processed more economically. Advantageously, during the reduction, the following elements are removed from the reaction product via the atmosphere/gas phase and separated in the filter device 54 with the specified separation degrees (based on the initial content in kg).

By the procedure according to the invention, the separation efficiencies listed in Table 1 are achieved for the elements mentioned:

Table 1: Separation efficiencies of selected volatile elements

The filter residues can optionally be further processed, in particular by washing or thermal treatment under oxidizing conditions, for example in the drum and/or rotary kiln 16, in order to separate the alkalis and the chlorine from the Zn and Pb oxides. The Zn and Pb oxides can optionally be further processed in a subsequent process under reducing conditions to metallic Zn and Pb (previously mentioned recovery of Zn and Pb).

After passing through the drum and/or rotary kiln 16, the reduced reaction product is collected in a closed container/collecting vessel 34 and protected from undesirable reoxidation. The material is then compacted, preferably hot or cold briquetted. This enables the product to be transported and stored as an HBI-like feedstock.

It is advantageous to add (bio-)C and lime to the briquetting process. This improves the melting behavior of the briquettes and the formation of slag in the melting unit.

The following additional features arise:

- advantageous pre-drying of possibly moist starting materials in order to (a) increase energy efficiency and (b) to advantageously reduce the exhaust gas volume flow, whereby a moisture content of < 10 wt. %, advantageously < 5 wt. %, calculated on the sum of the feedstocks, has an advantageous effect on the reduction kinetics when adding C-containing residues and

- the atmosphere inside 22 of the drum and/or rotary kiln 16 may contain, in addition to H2, the following components: CO, CO2, H2O, CH4

The composition of the gas introduced into the drum furnace/rotary kiln comprises reactive components, preferably either

- a mixture of H2 and H2O, where the hydrogen content is > 70 vol. %, advantageously > 80 vol. %, especially advantageously > 90 vol. %, accordingly H2O less than 30 vol. %, advantageously < 20 vol. %, especially advantageously < 10 vol. %, or

- a mixture of 5 to 90% by weight H2+ H2O, the remainder CO and CO2, wherein the weight ratio H2/H2O is > 2.3, advantageously > 4, particularly advantageously > 8 and the CO2 content in the supplied gas stream is limited to < 20 vol.%, advantageously < 10 vol.% and particularly advantageously < 5 vol.%

- The CO content is advantageously limited to < 30 vol.%

- other possible gas components, for example N2 < 30 vol.%, < 85 vol.% NH3 others in total < 10 vol.%. other process parameters

- the temperature in the furnace 16 is 830°C to 1030 °C, preferably 880°C to 990 °C; the throughput time of the feedstocks in the reduction area is 15 to 150 minutes.

The following waste materials can be used as input materials:

- for example filter dust from EAF, converter, vacuum treatment, hall dedusting, desulphurisation, blast furnace DR plant etc.,

- also scale, flame slag, chips, sludge (e.g. top sludge from blast furnaces, mill scale sludge from rolling mills, sludge from steelworks),

- other Fe-containing residues from non-steelworks industrial processes

- optionally, the residues have increased contents of Zn of > 2.5 wt.%, of alkalis (K2O and Na2Ö) of > 0.5 wt.% and of CI of > 0.15 wt.%.

- optionally, the residues contain oil residues,

- Grain size of the input materials is 85% < 10 mm, the rest may be oversize grain,

- optional: Fe content of the final product must not be less than 50 wt.%. reference sign

10 processing plant

12 residue mixtures

14 ovens

16 drum or rotary kiln

18 Longitudinal axis

20 rotary kilns

22 Interior (oven interior)

24 camps

26 drive

28 inlet

30 outlet

32 arrow (direction of travel)

34 containers

36 feeding device

38 Device for supplying a process gas

40 Control and/or regulating device

42 storage containers

44 conveyor system

46 H2 gas storage facilities

48 gas storage facilities (other gas)

50 dosing system

52 gas outlet

54 filter device

Claims

patent claims 1. Method for processing a residue mixture (12) containing the elements iron and/or calcium for industrial use by at least partially separating at least one volatile element, in particular the following list of elements: Zn, Pb, Na, K, CI, S, F and P, from this residue mixture (12) in a furnace (14), wherein this residue mixture (12) is designed as a granular residue mixture or at least has a granular portion, characterized in that the furnace (14) is designed as a drum or rotary kiln (16) and a process gas with a hydrogen content of more than 5% by volume, in particular of more than 50% by volume, is supplied to the drum or rotary kiln (16) for processing the residue mixture (12). 2. Method according to claim 1, characterized in that in the drum or rotary kiln (16), in addition to the separation of at least one volatile element from the residue mixture (12), a reduction of the element iron from the residue mixture (12) also takes place. 3. Method according to claim 1 or 2, characterized in that the granular residue mixture or the granular portion of the residue mixture (12) consists of particles whose particle size is 85% by weight smaller than 10 mm. 4. Method according to claim 3, characterized in that more than 50% by weight, in particular more than 80% by weight, of the granular residue mixture (12) or of the granular portion of the residue mixture (12) is in the form of dust and/or - preferably dried - sludge when it is filled into the drum or rotary kiln (16). 5. Method according to one of claims 1 to 4, characterized in that the residue mixture (12) contains, in addition to the elements iron and/or calcium, also the element carbon, preferably carbon of biogenic origin. 6. Process according to one of claims 1 to 5, characterized in that during the processing in the drum or rotary kiln (16) an atmosphere is formed which, in addition to hydrogen, also contains carbon monoxide - in a respective proportion of more than 5 % by volume. 7. Method according to one of claims 1 to 6, characterized in that the drum or rotary kiln (16) is operated at a furnace temperature of 830 °C to 1030 °C, preferably of 880 °C to 990 °C, during the processing of the residue mixture (12). 8. Process according to claim 7, characterized in that the residue mixture is exposed to the furnace temperature in the drum or rotary kiln (16) for a period of 15 minutes to 150 minutes during its processing in the furnace (16). 9. Method according to one of claims 1 to 8, characterized in that when separating the at least one volatile element from the residue mixture (12), this at least one volatile element is discharged via the atmosphere/a gas phase in the drum or rotary kiln (16) and separated in a filter device (54). 10. Computer program product comprising instructions which, when executed by a processor of a control and/or regulating device (40), cause this processor to carry out a method according to one of claims 1 to 9. 11. Processing plant (10) for processing a residue mixture (12) containing the elements iron and/or calcium for industrial use, with a furnace (14) for at least partially separating at least one volatile element, in particular the following list of elements: Zn, Pb, Na, K, CI, S, F and P, from this residue mixture (12), wherein this residue mixture (12) is designed as a granular residue mixture (12) or at least has a granular portion, characterized in that the furnace (14) is designed as a drum or rotary kiln (16) and the processing plant (10) has a device (38) for supplying a process gas into the drum or rotary kiln (16), which has a hydrogen portion of more than 5% by volume, in particular of more than 50% by volume. 12. Treatment plant according to claim 11, characterized in that the Device (38) for supplying the process gas a dosing system (50) for Provision of a selectable hydrogen content in the process gas. 13. Processing plant according to claim 11 or 12, characterized by gas-tight components (46, 48, 50) for using the process gas with hydrogen content, at least one of which is a component (46, 48, 50) of the device (38) for supplying the process gas into the drum or rotary kiln (16). 14. Processing plant according to one of claims 11 to 13, characterized by a control and/or regulating device (40) for controlling or regulating the operation of the processing plant (10). 15. Processing plant according to one of claims 11 to 14, set up to carry out the method according to one of claims 1 to 9.