Preparation of non-fossil coal from lignin

Abstract

The invention relates to a method for producing non-fossil coke from lignin, the method comprising the steps of: providing lignin; subjecting the lignin to increased pressure; subjecting the lignin to elevated temperature, wherein the combination of increased pressure and elevated temperature causes the release of volatile organic compounds (VOCs); and recovering the coke. The invention further relates to an apparatus (1000) for producing non-fossil coke from lignin, the use of the apparatus (1000) and the coke obtainable by the method.

Description

Technical Field

[0001] This invention relates to a method for preparing coke. Furthermore, this invention relates to an apparatus for producing non-fossil coke from lignin. Even further, this invention relates to coke that can be obtained by said method. Background Technology

[0002] Metallurgical coke is a high-carbon fuel primarily used in the steel manufacturing industry to provide heat and reduce iron oxide in iron ore. It is produced by heating coal under airless conditions, a process called "carbonization," which removes volatile components and leaves behind a carbon-rich, solid, porous material.

[0003] The process of preparing metallurgical coke includes the following steps: Coal selection and preparation: The coal used to produce metallurgical coke is typically high-quality bituminous coal with low sulfur and ash content. The coal is crushed and screened to remove any impurities.

[0004] Charging: Coal is loaded into the coke oven, a large refractory-lined furnace chamber. The furnace is then sealed, and natural gas or coke oven gas is used as fuel to gradually raise the temperature to approximately 2000°F (1093°C).

[0005] Carbonization: Coal is carbonized for about 18 to 24 hours, during which volatile components are removed, leaving solid coke.

[0006] Quenching: After the carbonization process is completed, water or air is used to quench the coke to cool it and prevent it from continuing to react.

[0007] Recycling: Collecting the volatile components that are expelled during carbonization and using them as fuel or chemical feedstock.

[0008] This method of producing metallurgical coke has several drawbacks. The carbonization process releases large amounts of greenhouse gases, such as carbon dioxide, and other pollutants into the atmosphere, exacerbating climate change and air pollution. Furthermore, coking plant workers may be exposed to potentially harmful gases such as benzene and ammonia, which can lead to health problems. Moreover, coal is a non-renewable resource, and traditional coke production methods rely on it. Coke production requires a large amount of energy, typically derived from fossil fuels, further increasing greenhouse gas emissions and exacerbating climate change.

[0009] Overall, the production of metallurgical coke is an important process for the steel industry, but it comes with several major drawbacks that need to be addressed to make the process more sustainable and environmentally friendly.

[0010] The process of producing coke from biomass is similar to that used in traditional coal-based coke production, but instead of coal, biomass such as sawdust or agricultural waste is used. The process involves heating the biomass in an anaerobic environment to produce a solid, high-carbon fuel.

[0011] The process of preparing biomass coke includes the following steps: Biomass selection and preparation: The biomass used to produce coke must be of high quality and free of contaminants such as sand, stones, or metals. The biomass is crushed, sieved, and dried to remove any moisture.

[0012] Charging: The prepared biomass is loaded into a coke oven, which is similar to the coke oven used in traditional coke production.

[0013] Carbonization: Biomass is carbonized at a high temperature of approximately 1200°C to 1500°C for several hours. During carbonization, volatile components are removed, leaving a carbon-rich solid porous material.

[0014] Coke quenching: After the carbonization process is completed, the coke is cooled with water or air to prevent further reaction.

[0015] Recycling: Volatile components removed during carbonization can be collected and used as fuel or chemical feedstock.

[0016] The amount of biomass available for coke production is limited, and the production cost of biomass coke is higher than that of conventional coke due to the higher cost of raw materials and the technologies used. Biomass coke also has a lower energy density than conventional coke, making it unsuitable for certain industrial processes. There are also concerns that the production of biomass coke could lead to deforestation and habitat loss.

[0017] Compared to traditional coal-based coke, biomass coke has the potential to be a more sustainable and environmentally friendly option. Biomass is a renewable resource, and using it in coke production can reduce dependence on non-renewable coal. However, the higher cost and lower energy density of biomass coke may limit its widespread adoption in industrial applications. Furthermore, further research and development are needed to optimize the production process and reduce environmental impact. Summary of the Invention

[0018] One object of the present invention is to overcome at least some of the aforementioned problems and to provide a method for producing non-fossil coke from lignin. Aspects of the invention are defined in the independent claims. According to a first aspect of the invention, a method for producing non-fossil coke from lignin as defined in claim 1 is provided. According to a second aspect of the invention, an apparatus for producing non-fossil coke from lignin as defined in claim 11 is provided. According to a third aspect of the invention, the use of the apparatus of the second aspect as defined in claim 15 is provided. According to a fourth aspect of the invention, coke obtainable by the method of the first aspect as defined in claim 16 is provided.

[0019] Surprisingly, it has been found that high-quality lignin coke can be prepared through this invention, which has a high energy density similar to that of conventional metallurgical coke and contains more non-fossil carbon than biomass coke. Attached Figure Description

[0020] The invention will now be described in more detail with reference to the accompanying drawings, which illustrate an apparatus for producing non-fossil coke from lignin. Detailed Implementation

[0021] This invention relates to a method for producing non-fossil coke from lignin, in which the lignin is subjected to elevated temperatures and increased pressures, thereby releasing volatile organic compounds (VOCs) from the lignin during the coking process. These VOCs can be recovered for further processing. After the VOC release, coke is recovered, the coke having a Hardness represented by a Hard Grove Grindability Index (HGI) in the range of 30 to 90 and a Porosity in the range of 35% to 55%. The recovered high-quality coke is suitable, for example, to replace all or at least a portion of the coke in metallurgical processes. The invention also relates to an apparatus for carrying out the method. Figure 1 An embodiment of the device is shown.

[0022] Figure 1An apparatus 1000 according to at least some embodiments is shown. In one embodiment, the apparatus includes a storage silo 20 for storing lignin, from which lignin is supplied to a solid base 30. The lignin is supplied from the silo 20 to the solid base 30 in a coke oven 120 by means of a feed conveyor 40 adapted to transfer the lignin feedstock from the storage silo 20 to the solid base 30. The solid base 30 is adapted to convey the lignin through the coke oven to a first calendering roll 60, wherein heat 50 for heating the lignin and intermediate products in the coking process is applied to the first calendering roll 60. The first calendering roll 60 is equipped with means 70 for applying pressure to the lignin and intermediate products in the coking process. When the lignin and intermediate products are heated 50 and pressurized 70 through the first calendering roll 60, VOCs are released, which are optionally directed to a recovery 80 for further use. Optionally, one or more additional calendering rolls 65 are provided, similarly adapted to apply heat 55 and pressure 75 to the lignin and intermediate products. After being subjected to pressure 70 and heat 55 by the first calendering roll 60 and optionally the additional calendering rolls 65, coke is formed. After optional cooling and heat recovery 90, the coke is conveyed from the coke oven 120 to the coke storage device 110, optionally via a conveyor 100.

[0023] As described above, this technology relates to a method for producing non-fossil coke from lignin. In one embodiment, the method includes the steps of: providing lignin; subjecting the lignin to increased pressure; subjecting the lignin to increased temperature, wherein the combination of increased pressure and increased temperature causes the release of volatile organic compounds (VOCs); and recovering the coke. Lignin is typically provided in the form of lignin fragments; however, in some embodiments, lignin is provided in the form of aqueous pulp, for example, in one embodiment, lignin precipitated from black liquor in a pulp mill is the lignin source.

[0024] Lignin is a complex organic polymer found in the cell walls of many plant species. In one embodiment, lignin is obtained from softwood. Softwood is commonly used in a variety of applications, such as construction, furniture, paper, and packaging materials. The specific properties and characteristics of each type of wood may depend on where and how the wood is grown and how it is processed. However, all softwoods contain lignin. In one embodiment, lignin is obtained from softwoods selected from: pine, spruce, fir, cedar, hemlock, Douglas fir, redwood, yew, juniper, larch, American larch, western red cedar, eastern white pine, white cedar, and mixtures thereof.

[0025] In another embodiment, lignin is obtained from hardwoods. Hardwoods are commonly used, for example, in the manufacture of furniture and flooring. Like softwoods, the properties of hardwoods can also depend on their growth and processing conditions. In another embodiment, lignin is obtained from hardwoods selected from: oak, maple, cherry, walnut, ash, birch, hickory, mahogany, teak, poplar, beech, sycamore, elm, alder, ebony, eucalyptus, and mixtures thereof.

[0026] Other sources of lignin are also used in the various embodiments. In one embodiment, lignin is obtained from agricultural residues. Upgrading agricultural residues that would normally be left to decompose or burn provides a valuable source of renewable lignin. In one embodiment, lignin is obtained from agricultural residues selected from: wheat straw, rice straw, bagasse, and mixtures thereof. In one embodiment, lignin is obtained from energy crops typically grown for bioenergy production. In one embodiment, lignin is obtained from at least one energy crop selected from: willow, miscanthus, and switchgrass.

[0027] It has been found that lignin from different sources can be mixed and used together. For example, lignin obtained from hardwood can be mixed with lignin obtained from softwood. Similarly, lignin contained in hardwood can be mixed with lignin obtained from agricultural residues. Furthermore, lignin obtained from softwood can be mixed with lignin obtained from agricultural residues. In one embodiment, the lignin is obtained from the group consisting of hardwood, softwood, agricultural residues, and mixtures thereof.

[0028] As mentioned above, lignin can be obtained from industrial residues such as black liquor. Historically, black liquor was evaporated to increase its solids content, then injected into a furnace and burned, thereby recovering process chemicals valuable to pulp mills. Because lignin recovered from black liquor has an unpleasant odor, it is typically burned. However, lignin has become a valuable resource and can be recovered from black liquor by various methods. Typically, lignin is recovered from black liquor through precipitation processes, such as acid precipitation. Therefore, in one embodiment, lignin is obtained from black liquor in a pulp mill. In another embodiment, lignin is recovered from black liquor through a precipitation process. In yet another embodiment, lignin is recovered from black liquor through an acid precipitation process.

[0029] As described above, lignin is provided and subjected to increased pressure. In one embodiment, the increased pressure is provided by bringing the lignin into contact with the outer surface of a first calender roll and the planar surface of the bed, wherein the calender roll is adapted to move perpendicular to the bed. The pressure is provided by a mechanical load applied by the calender roll to the lignin located on the planar surface of the bed.

[0030] In another embodiment, pressure is provided by contacting the lignin with the outer surfaces of the first calender roll and the lower calender roll, wherein at least one of the first and lower calender rolls is adapted to move perpendicular to the lower or first calender roll. The perpendicular movement of the first and / or lower calender roll relative to the lower and first calender rolls applies a mechanical load to the lignin in contact with the calender rolls. For various embodiments, the term "lower" with respect to the lower calender roll means that the calender roll is located below or beneath the first calender roll. In one embodiment, the pressure exerted on the lignin is increased to 0.5–5 kg / cm². 2 The pressure range is suitable to be 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8 or 4.9 kg / cm². 2 .

[0031] To release VOCs, the lignin is heated in addition to being subjected to pressure. In one embodiment, the lignin is heated by at least one surface in contact with it, for example, at least a planar surface or a first calender roll. In another embodiment, the lignin is heated by more than one surface in contact with it, for example, simultaneously heating a planar surface and a first calender roll, or simultaneously heating a first calender roll and a lower calender roll.

[0032] The surface to be heated can be heated in a variety of ways. For example, in one embodiment, steam is used to heat the one or more surfaces. In another embodiment, electricity is used to heat the one or more surfaces. In one embodiment, a combustible gas is used to heat the one or more surfaces.

[0033] In one embodiment, the lignin is subjected to a temperature in the range of 50–600°C, preferably 100–500°C, suitably 200–400°C, particularly 250–350°C, for example about 260, 270, 280, 290, 300, 310, 320, 330 or 340°C.

[0034] As described above, the combination of heating and pressurization leads to the release of VOCs. In one embodiment, VOCs are recovered for further processing. VOCs refer to all organic compounds that exist in a gaseous or highly volatile liquid state at normal room temperature. VOCs refer to all organic compounds that have a vapor pressure equal to or greater than 0.01 kPa at 20°C, or that have equivalent volatility under specific usage conditions. VOC chains typically have fewer than twelve carbon atoms and contain other elements such as oxygen, fluorine, chlorine, bromine, sulfur, or nitrogen. In one specific embodiment, the recovered VOCs are burned to provide at least a portion of the heat for heating the surface of the flat surface and / or the surface of the first calender roll, or the surface of the first calender roll and / or the surface of the lower calender roll. Increased pressure and elevated temperature are applied until the coke to be recovered has the desired porosity and desired hardness.

[0035] The ideal porosity and hardness of metallurgical coke can vary depending on the specific requirements of the steelmaking process and the particular blast furnace in which the coke will be used. However, generally speaking, there are certain ranges of porosity and hardness considered suitable for metallurgical coke used in steelmaking processes.

[0036] Porosity refers to the amount of voids or pores within coke. In the context of metallurgical coke, porosity is an important factor because it affects the permeability of coke in a blast furnace. Higher porosity allows gases to flow more easily through the coke bed, and the reaction between the coke and the hot gases proceeds more rapidly. The porosity of coke can be measured using various methods, such as mercury intrusion porosimetry (MIP) (ISO 15901-1:2016) or gas adsorption (ISO 15901-2:2022). In MIP, mercury is forced into the pores of the coke under high pressure, and the volume of mercury absorbed is measured. In gas adsorption, the coke is exposed to a gas, typically nitrogen, and sometimes carbon dioxide, and the amount of gas absorbed by the coke is measured.

[0037] The porosity of metallurgical coke used in steelmaking typically falls between 25% and 35%. This porosity level allows for sufficient gas flow through the coke bed in the blast furnace, which is essential for the reduction of iron oxide and steel production.

[0038] Therefore, in one embodiment, the lignin is subjected to increased pressure and elevated temperature until the resulting coke has a porosity in the range of 20% to 40%, preferably 25% to 35%, such as 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33% or 34%, as measured by MIP according to ISO 15901-1:2016 and / or by gas adsorption method according to ISO 15901-2:2022.

[0039] Hardness refers to a material's resistance to deformation, indentation, or scratching. In the context of metallurgical coke, hardness is important because it affects the coke's strength and its ability to withstand the weight of materials above it in the blast furnace.

[0040] The hardness of coke is typically measured according to ASTM D409-17. The coke sample is crushed and sieved to a suitable particle size range for testing, typically 0.6–1.8 mm. A weighed coke sample (typically 50 g) is placed in a ball ring mill and rotated at 60 revolutions per minute (rpm). After a specified grinding time, such as 600 revolutions per minute or 10 minutes, the mill is stopped, and the ground material is sieved through a standard 75-micron sieve. The undersize portion is expressed as a percentage of the total sample, and the HGI is calculated using the formula HGI = 100(-undersize percentage × 1.7), where 1.7 is a constant for converting the undersize percentage to the HGI scale. The test is repeated at least twice to obtain an average HGI value.

[0041] The hardness of metallurgical coke used in steelmaking typically ranges from 60 to 90 HGI (Hardgrove Grindability Index). This hardness level ensures that the coke can withstand the weight of the material above it in the blast furnace and maintain its structural integrity during the steelmaking process.

[0042] Therefore, in one embodiment, the lignin is subjected to increased pressure and elevated temperature until the resulting coke has a hardness in the range of 50 to 100 HGI, preferably 60 to 90 HGI, for example, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88 or 89 HGI as measured according to ASTM D409-17.

[0043] The exact porosity and hardness requirements of coke depend largely on the application to which it will be used. Therefore, porosity and hardness can be adjusted as needed by varying the duration of increased pressure and elevated temperature.

[0044] Another embodiment relates to an apparatus for producing non-fossil coke from lignin. In one embodiment, the apparatus includes: a lignin inlet; a first calendering roll; a lower calendering roll or solid base (located at a frame), wherein the first calendering roll and the lower calendering roll or solid base are configured to press against each other; a surface for receiving lignin from the inlet at one of the calendering rolls or the solid base; a heating device for heating at least one of the following: the surface for receiving lignin, the first calendering roll, and the solid base or second calendering roll; an outlet for discharging VOCs released during the pressurization and heating of the lignin; and an outlet for recovering the coke.

[0045] In one embodiment, the surface used to receive lignin is a solid base or a lower calendering roll. In another embodiment, the first calendering roll and the lower calendering roll or solid base are configured to press against each other to apply pressure to the lignin, preferably increasing the pressure on the lignin to a range of 0.5–5 kg / cm², suitably 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8 or 4.9 kg / cm². Applying pressure and heat to lignin releases VOCs from it, leaving behind non-fossilized coke, which has a hardness and porosity particularly suitable for use as metallurgical coke. Therefore, in one embodiment, the method is carried out using the aforementioned equipment.

[0046] As described above, non-fossil coke with a hardness and porosity suitable for use as metallurgical coke can be obtained by the method described above. Similarly, non-fossil coke suitable for use as metallurgical coke can be obtained using the equipment described above. Therefore, one embodiment relates to non-fossil coke that can be obtained by the method described above.

[0047] Industrial applicability

[0048] Embodiments of the present invention can be used to produce non-fossil coke from lignin, such as lignin recovered as a byproduct from pulp mill processes. The methods and apparatus are also suitable for coking lignin from a variety of different sources, ranging from hardwoods and softwoods to agricultural residues and energy crops.

Claims

1. A method for producing non-fossil coke from lignin, the method comprising the following steps: Provides lignin; The lignin is subjected to increased pressure; The lignin is subjected to elevated temperatures, wherein the combination of increased pressure and elevated temperature causes the release of volatile organic compounds; and Recycle coke.

2. The method according to claim 1, wherein the lignin is obtained from softwood, preferably from softwood selected from: pine, spruce, fir, cedar, hemlock, Douglas fir, redwood, yew, juniper, larch, American larch, western red cedar, eastern white pine, white cedar and mixtures thereof.

3. The method according to claim 1, wherein the lignin is obtained from hardwood, preferably from hardwood selected from: oak, maple, cherry, walnut, ash, birch, hickory, mahogany, teak, poplar, beech, sycamore, elm, alder, ebony, eucalyptus, and mixtures thereof.

4. The method according to any one of the preceding claims, wherein the lignin is obtained from a pulp mill, and in particular, the lignin is obtained from black liquor of a pulp mill, preferably by precipitation.

5. The method according to any one of the preceding claims, wherein increased pressure is provided by contacting the lignin with the outer surface of the first calender roll (60) and the planar surface of the bed, wherein the calender roll is adapted to move perpendicular to the bed.

6. The method according to any one of claims 1 to 4, wherein pressure is provided by contacting lignin with the outer surface of the first calender roll and the outer surface of the lower calender roll, wherein at least one of the first calender roll (60) and the lower calender roll is adapted to move perpendicular to the lower calender roll or the first calender roll (60).

7. The method according to any one of the preceding claims, wherein at least one surface in contact with the lignin is heated.

8. The method according to any one of the preceding claims, wherein more than one surface in contact with the lignin is heated.

9. The method according to any one of the preceding claims, wherein the pressure subjected to the lignin is increased to 0.5–5 kg / cm². 2 The pressure range is suitable to be 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8 or 4.9 kg / cm². 2 .

10. The method according to any one of the preceding claims, wherein the lignin is subjected to a temperature in the range of 50–600°C.

11. The method according to any one of the preceding claims, wherein the VOC is recovered for further processing.

12. An apparatus (1000) for producing non-fossil coke from lignin, comprising: frame; Lignin enters the body; First calendering roll (60); A lower calendering roll or solid base (30) is disposed at the frame, wherein the solid base (30) is adapted to convey lignin through the coke oven to a first calendering roll (60), and wherein the first calendering roll (60) and the lower calendering roll or solid base (30) are configured to press against each other to apply 0.5–5 kg / cm² to the lignin. 2 Pressure within the range; A surface for receiving lignin from the inlet at one of the calendering rolls or at a solid base (30); A heating device (50) is used to heat at least one of the following: a surface for receiving lignin, a first calendering roll (60), and a solid base (30) or a second calendering roll (65). Outlet (80) for discharging VOCs released during the pressurization and heating of lignin from the device; as well as Exported for the purpose of recycling coke.

13. The apparatus (1000) according to claim 12, wherein the surface for receiving lignin is a solid base (30) or a lower calendering roll.

14. The apparatus (1000) according to claim 12 or 13, wherein the first calendering roll (60) and the lower calendering roll or solid base (30) are configured to press against each other to apply pressure to the lignin, preferably increasing the pressure on the lignin to a suitable value of 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8 or 4.9 kg / cm². 2 The pressure.

15. Use of the device (1000) according to any one of claims 12 to 14 in the method according to any one of claims 1 to 11.

16. Coke that can be obtained by the method according to any one of claims 1 to 11.

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