Method and system for agglomerating coke particles

Abstract

The present disclose describes a method (100) and system (200) for agglomerating coke particles The method (100) comprising pre-mixing (110) coke particles and a binder into a pre-mixed blend, paddle mixing (120) the pre-mixed blend into a paddle mixed blend in a continuous paddle mixer (220), where the continuous paddle mixer (220) comprises a mixing chamber (221), a shaft (222), and a plurality of paddles (223) connected to the shaft (222) along the longitudinal direction (224) of the shaft (222), where at least one paddle is rotatably connected to the shaft (222) such that the angle (225) of the at least one paddle is adjustable, and carbonizing (130) the paddle mixed blend, where, during paddle mixing (120) the, the continuous paddle mixer (220) is arranged such that the shaft (222) is aligned substantially horizontal, and where the pre-mixed blend is heated to a temperature of at least 80 °C.

Description

Method and system for agglomerating coke particlesField of inventionThe present invention relates to the field of agglomeration of coke.Background

[0001] The demand for synthetic graphite has increased significantly in recent years, largely due to its use as anode material in lithium ion batteries.

[0002] The process of producing synthetic graphite from coke particles may generally be subdivided into three steps, i) an agglomeration step, ii) a calcination step, and iii) a graphitization step. According to state of the art, the agglomeration step is subdivided into sub steps including a step of pre-mixing a batch of coke particles and a binder, and a step of hot mixing the batch of pre-mixed coke particles and binder by exposing the batch to a heat treatment program. The step of hot- mixing is generally performed by feeding the batch of pre-mixed coke particles and binder into a hot mixer followed by slowly heating the batch to a temperature suitable for carbonization over a period of several hours. When the temperature program is finished, the batch is transferred to a cooling mixer while the hot mixer is cooled and prepared for the next batch. The cycle time for a typical hot mixer according to the state of the art is generally approximately 10 - 12 hour, thereby defining a lower time requirement for agglomerating coke particles with a binder.

[0003] It is an aim of the present invention to provide a method for agglomerating coke particles that addresses some of the issues with the prior art.Summary of the invention

[0004] A first aspect of the present invention provides a method for agglomerating coke particles, the method comprising pre-mixing coke particles and a binder into a pre-mixed blend, paddle mixing the pre-mixed blend into a paddle mixed blend in a continuous paddle mixer, where the continuous paddle mixer comprises a mixing chamber, a shaft, and a plurality of paddles connected to the shaft along the longitudinal direction of the shaft, where at least one paddle is rotatably connected to the shaft such that the angle of the at least one paddle is adjustable, and carbonizing the paddle mixed blend, where, during paddle mixing, the continuous paddle mixer is arranged such that the shaft is aligned substantially horizontal, and where the pre-mixed blend is heated to a temperature of at least 80 °C.

[0005] In an embodiment of the invention the method comprises continuously feeding the continuous paddle mixer with the premixed blend.

[0006] In another embodiment of the invention the mixing chamber of the continuous paddle mixer is cylindrical and comprises a cylindrical chamber wall, a first end and a second end, and where each of the plurality of paddles is arranged with a separation distance from the cylindrical chamber wall of less than 3 mm.

[0007] In yet another embodiment of the invention the continuous paddle mixer is provided with an inlet at the first end and an outlet at the second end.

[0008] In yet another embodiment of the invention the plurality of paddles are arranged to provide continuous paddle mixing along the full length of the mixing chamber.

[0009] In yet another embodiment of the invention each paddle comprises a blade having a width in the range 20 - 100 mm, preferably in the range 25 - 50 mm, most preferably in the range 30 - 35 mm.

[0010] In yet another embodiment of the invention the continuous paddle mixer comprises an inlet and where the inlet is provided with a cooler.

[0011] In yet another embodiment of the invention each paddle is rotated by a speed in the range 25 m / s - 70 m / s measured at the tip of said paddle.

[0012] In yet another embodiment of the invention the coke particles and the binder are introduced into the pre-mixer in powder form.

[0013] In yet another embodiment of the invention the residence time of any portion of the pre-mixed blend in the continuous paddle mixer is less than 1 minute.

[0014] A first aspect of the present invention provides a system comprises a pre-mixer configured to pre-mix coke particles and a binder into a pre-mixed blend, a continuous paddle mixer, comprising a mixing chamber, a shaft, a plurality of paddles connected to the shaft along the longitudinal direction of the shaft, where at least one paddle is rotatably connected to the shaft such that the angle of the at least one paddle is adjustable, and a carbonizer configured to carbonize the paddle mixed blend, where the continuous paddle mixer is configured to paddle mix the pre-mixed blend into a paddle mixed blend, to operate with the shaft being aligned substantially horizontal, and to heat the pre-mixed blend to a temperature of at least 80 °C.

[0015] In an embodiment of the invention the mixing chamber of the continuous paddle mixer comprises a chamber wall and where each of the plurality of paddles is arranged with an adjustable separation distance from the chamber wall.

[0016] In another embodiment of the invention the mixing chamber of the continuous paddle mixer is cylindrical and comprises a cylindrical chamber wall, a first end and a second end, and where each of the plurality of paddles is arranged with a separation distance from the cylindrical chamber wall of less than 3 mm.

[0017] In yet another embodiment of the invention the continuous paddle mixer is configured to rotate the shaft such that each paddle is rotated by a speed in the range 25 m / s - 70 m / s measured at the tip of the paddle.

[0018] In yet another embodiment of the invention the continuous paddle mixer comprises an inlet and where the inlet is provided with a cooler.Brief description of the drawings

[0019] Figure 1 is a schematic illustration of a method for agglomerating coke particle according to the present invention,

[0020] Figure 2 is a schematic illustration of a system for agglomerating coke particle according to the present invention, and

[0021] Figure 3 is a schematic illustration of a continuous paddle mixer.Detailed description of the invention

[0022] In the following, general embodiments as well as particular exemplary embodiments of the invention will be described. References will be made to the accompanying drawings. It shall be noted, however, that the drawings are exemplary embodiments only, and that other features and embodiments may well be within the scope of the invention as claimed. Further, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The term "invention" may herein be used interchangeably with the term "disclosure". The term "producing" may herein be used interchangeably with the term "obtaining".

[0023] Unless otherwise defined, all terms of art, notations and other scientific terms or terminology used herein are intended to have the meanings commonly understood by those of skill in the art to which this invention pertains. Certain terms of art, notations, and other scientific terms or terminology may, however, be defined specifically as indicated below.

[0024] The present invention provides a method and a system for agglomerating coke particles. The present invention is generally based on the employment of a continuous paddle mixer in the process of agglomerating coke particles, more specifically on the employment of a continuous paddle mixer in an agglomeration line between a pre-mixer and a carbonizer.

[0025] Figure 1 schematically illustrates the method 100 according to the present invention, where the method 100 comprises pre-mixing 110 coke particles and a binder into a pre-mixed blend, paddle mixing 120 the pre-mixed blend into a paddle mixed blend in a continuous paddle mixer 220, and carbonizing 130 the paddle mixed blend. As will be appreciated by a person skilled in the art, thesystem 200 described herein, schematically illustrated in figure 2, may generally be employed in order to carry out the method 100. Various components of the system 200 may thus be configured to perform at least part of the method 100.

[0026] Figure 2 schematically illustrates a system 200 according to the present invention. The system comprises a pre-mixer 210 configured to pre-mix coke particles and a binder into a pre-mixed blend, a continuous paddle mixer 220 configured to paddle mix the pre-mixed blend into a paddle mixed blend, to / at a temperature of at least 80 °C, and a carbonizer 240 configured to carbonize the paddle mixed blend. The pre-mixed blend may be transported from the premixer 210 to the continuous paddle mixer 220, and the paddle mixed blend may be transported from the continuous paddle mixer 220 to the carbonizer 240 by suitable transport means 231.

[0027] Pre-mixing of coke particles and a binder into a pre-mixed blend may generally be performed in any suitable mixer, herein generally referred to as a pre-mixer. Examples of suitable pre-mixers include a standard batch based paddle mixer, a screw mixer, and a drum mixer. Pre-mixing of coke particles and a binder may be performed in order to form a homogeneous mix of coke particles and a binder, and may thus be performed over a time period that may be adjusted according to a predetermined homogeneity. The coke particles and the binder may both be in dry form prior to being pre-mixed, optionally with a D50 particle size in the range 1 micron - 100 micron, or preferably with a D50 particle size of in the range 2 micron - 25 micron.

[0028] The temperature during pre-mixing may generally be kept at room temperature, e.g., in the range 1 - 40 °C, preferably in the range 10 °C - 30 °C. More particularly the temperature during pre-mixing may be kept below the softening point, or at least below the liquidation point, of the binder. The latter is preferable when pre-mixing coke particles and a binder in a dry form, as a temperature below the softening point of the binder may limit unwanted agglomeration during pre-mixing. In a particular example, the temperature during pre-mixing is kept below 250 °C, preferably below 40 °C. The latter has been found to be beneficial as many binders become sticky at temperatures above said threshold. . As will be appreciated by a person skilled in the art with knowledge of the present invention, a variety of binders may generally be employed. As a way of example, the binder may comprise or consist of any one or more of pitch, lignin and lignosulfonate. The binder may preferably be pitch. Liquidation point may, as will be appreciated by a person skilled in the art generally be defined as the temperature where a substance becomes liquid over a practical time limit.

[0029] Once a pre-mixed blend of coke particles and a binder is obtained, said premixed blend may be subjected to paddle mixing in a continuous paddle mixer 220. The pre-mixed blend may, as schematically illustrated in figure 2, for example be transferred from the pre-mixer 210 to the continuous paddle mixer 220 by any suitable transport means 231, such as via suction, screw feeder etc., and optionally assisted by gravity. The pre-mixed blend may be introduced into the continuous paddle mixer 220 at a stable rate, e.g. by suitable transport means 231, for example a screw feeder. The introduction of the pre-mixed blend into the continuous paddle mixer 220 has been found to be preferable in order to ensure a stable output rate from the continuous paddle mixer 220 and thus also in order to ensure a stable and consequently homogeneous treatment of the premixed blend in the continuous paddle mixer 220.

[0030] As schematically illustrated in figures 2 and 3, the continuous paddle mixer 220 comprises a mixing chamber 221, a shaft 222 and a plurality of paddles 223 connected to the shaft 222 along the longitudinal direction 224 of the shaft 222. The mixing chamber 221 may generally take on a variety of shapes, but is preferable cylindrical or conical. The shaft 222 may extend through the mixing chamber 221, and may be configured to rotate within the mixing chamber 221, for example by means of a motor 230 located on the outside on the mixing chamber 221. The plurality of paddles 223 connected to the shaft 222 along the longitudinal direction 224 of the shaft 222 may be configured to perform paddle mixing of the pre-mixed blend and be configured to drive the pre-mixed blend through the mixing chamber 221. As a way of example, the pre-mixed blend may enter the mixing chamber 221 at one end before being continuously paddle mixed and simultaneously transferred through the mixing chamber 221 by means of the plurality of paddles 223, before exiting the continuous paddle mixer at an outlet of the mixing chamber 221 as a paddle mixed blend. A paddle 223 may generally herein be considered as a mixing blade, or more generally as a mixing element configured to perform mixing.

[0031] In order to drive the pre-mixed blend through the mixing chamber 221, at least one of the plurality of paddles 223 connected to the shaft 222 may be arranged at a non-zero angle 225. More specifically, as schematically illustrated in figure 3, the at least one paddle 223 may be arranged with a non-zero angle 225 relative to the longitudinal direction 224 of the shaft 222. Said angle 225 may cause the paddle 223 to apply a force to the pre-mixed blend as the paddle 223 impacts the pre-mixed blend, thereby forcing the pre-mixed blend forward through the mixing chamber 221. More generally, any one or more of the plurality of paddles 223 connected to the shaft 222 along the longitudinaldirection 224 of the shaft 222 may be arranged with a non-zero angle 225 relative to the longitudinal direction 224 of the shaft 222. The alignment, e.g. the rotational alignment, of the paddles 223 may generally be chosen to determine the residence time of the pre-mixed blend inside the mixing chamber 221 of the continuous paddle mixer 220 and thus for example the degree of mixing and / or the heating of the pre-mixed blend. In a particular embodiment of the present invention, any one or more of the plurality of paddles 223 may be rotatably connected to the shaft 222 such that the angle 225 of said paddle(s) is adjustable. The latter enables customization of the operation of the continuous paddle mixer 220, i.e., that the residence time of the pre-mixed blend in the continuous paddle mixer 220 may be adjusted on demand. Different residence times may be preferable for different types pre-mixed blends, for example based on particle sizes, binder type, etc.

[0032] The continuous paddle mixer 220 may, as schematically illustrated in figures 2 and 3, be arranged such that the shaft 222 is aligned in a substantially horizontal direction, i.e., such that the angle between the longitudinal direction 224 of the shaft and the horizontal plane is less than 45 °. The shaft 222 is preferably aligned with a angle relative to the horizontal plane of less than 10 °, more preferably with an angle of less than 2 °, and most preferably with an angle of 0 °. The mixing chamber 221 may generally be arranged with the same angle relative to the horizontal plane as the shaft 222. In a particular example, the mixing chamber 221 may be cylindrical, and the shaft 222 may be linear and arranged along the central axis of the mixing chamber 221. A substantially horizontal arrangement of the shaft 222 and the mixing chamber 221 is preferred as it limits the influence of gravity on the movement of the pre-mixed blend though the mixing chamber 221 and allows for control of residence time of the pre-mixed blend inside the mixing chamber 221.

[0033] The continuous paddle mixer may according to the present invention be configured to heat the pre-mixed blend to a temperature of at least 80 °C. Said temperature may be employed in order to bring the pre-mixed blend to a temperature above the softening point of the binder. As various binders have various softening points, the exact temperature may vary, and may thus generally be at least T, where T is in the range 80 °C - 350 °C. As a way of example, when pitch is used as a binder, the continuous paddle mixer may be configured to heat the pre-mixed blend to a temperature of at least T, where T is in the range 80 °C - 250 °C. Said temperature limit may be chosen as most pitches has a softening point in the range 80 °C to 250 °C. Since most types of pitch practically liquidize, i.e., obtain a liquidity that allows for liquid behaviourwithin a practical time period, at a temperature approximately 50 °C above the softening point, the continuous paddle mixer may be configured to heat the premixed blend to a temperature of at least T, where T is in the range 130 °C - 300 °C. The continuous paddle mixer may thus simultaneously heat and paddle mix the pre-mixed blend, thereby forming a paddle mixed blend. Heating the pre-mixed blend to temperature of at least 80 °C has empirically been found to be preferable in order to ensure that the binder employed reaches a viscosity that enables agglomeration of the binder and the coke particles in the pre-mixed blend. By combining mixing with heating in the continuous paddle mixer, the pre-mixed blend may be turned into a paddle mixed blend, where the paddle mixed blend may comprise agglomerates of coke particles and binder.

[0034] The continuous paddle mixer may in an embodiment of the present invention be configured to heat the pre-mixed blend to a temperature of at most 350 °C. Performing paddle mixing at a temperature below the carbonization temperature of the binder may in certain processes be preferable in order to ensure a homogeneous paddle mixed blend with a limited number of carbonized clusters and / or limits the production of flue gas. It may also further be preferable that the continuous paddle mixer is configured to heat the pre-mixed blend at temperatures close to the softening point or melting point of the binder, i.a. in order to save energy and to reduce equipment wear. A temperature of at most 350 °C has been found empirically to be preferred in order to limit power consumption and equipment wear. In a particular example the continuous paddle mixer may be configured to heat the pre-mixed blend to a temperature of at most 520 °C. The latter is particularly preferable when using pitch as a binder, as the carbonization threshold for pitch lies generally around 520 °C.

[0035] The paddle mixed blend may, as schematically illustrated in figure 1 and 2, subsequently to leaving the continuous paddle mixer 220 be transferred to a carbonizer 240 and carbonized. The paddle mixed blend may for example be transferred between the continuous paddle mixer 220 and the carbonizer 240 by a suitable transport means 231, for example by one or more of gravity, a screw mixer, by vacuum etc. The carbonizer 240 may generally be a heat treatment unit configured to carbonize the paddle mixed blend, and may for example be a standard batch based hot mixer or generally a device configured to heat the paddle mixed blend to a temperature suitable for causing carbonization, optionally while stirring the paddle mixed blend. Carbonization may generally be performed in order to solidify the binder, and thus to form solid agglomerates of coke and carbonized binder. The carbonization may generally be performed under inert conditions.

[0036] The carbonizing of the paddle mixed blend may for example be performed at a temperature in the range 500 - 1200 °C, optionally in the range 600 - 650 °C. The latter range has been found to be preferable for ensuring desirable carbonization of the paddle mixed blend while keeping the power consumption and equipment wear within acceptable limits. The duration of the carbonization treatment may generally be in the range 2 - 3 hours, but may vary based on for example the volume, particle size, binder type etc. of the paddle mixed blend. Since the paddle-mixed blend is already agglomerated when exiting the continuous paddle mixer, the carbonizer may be kept constantly at a high temperature without having to undergo time consuming cooling between batches.

[0037] The shaft of the continuous paddle mixer may generally according to the present invention be rotated in order to expose the pre-mixed blend to high shear forces inside the mixing chamber. Said high shear forces may generally cause the formation of a paddle mixed blend with homogeneous particle size, and with homogeneous distribution of binder. Generally the continuous paddle mixer may be configured such that each paddle is rotated with a speed of at least 25 m / s, preferably in the range 25 m / s - 70 m / s, measured at the tip of said paddle. As will be appreciated by a person skilled in the art with knowledge of the present invention, the exact speed of the paddles may vary for example with the holding time of the pre-mixed blend inside the mixing chamber of the continuous paddle mixer. A speed of at least 25 m / s, preferably in the range 25 m / s - 70 m / s, of each paddle measured at the tip of said paddle has been found to be suitable for obtaining a paddle mixed blend with homogeneous particle size, and with homogeneous distribution of binder.

[0038] The residence time of any portion of the pre-mixed blend in the continuous paddle mixer may generally be less than 1 minute. However, as will be appreciated by a person skilled in the art with knowledge of the present invention, the exact residence time may vary based on for example the desired properties of the paddle mixed blend, the velocity of the paddles, the angle of the paddles, the binder type, the coke particle size etc. It has been found empirically that suitable results are obtained by keeping the residence time below 1 minute. A residence time in the order of 1 minute is preferred in order to maintain a desirable output, and thereby reducing the power consumption and equipment wear of the continuous paddle mixer.

[0039] As schematically illustrated in figure 3, the continuous paddle mixer 220 may comprise a mixing chamber 221 where the mixing chamber 221 is cylindrical and comprises a cylindrical chamber wall, a first end 242 and a second end 243. Acylindrical mixing chamber is preferred in order to ensure even conditions inside the continuous paddle mixer 220 along the full length of the mixing chamber 221. As further schematically illustrated in figure 3, each of the plurality of paddles 223 may be arranged such that the tip of each paddle is verging to the wall of the mixing chamber, i.e., where tip of each paddle is close but not touching the wall of the mixing chamber. Such an arrangement of the plurality of paddles 223 is preferable in order to limit the build-up of material along the wall of the mixing chamber 221. In a particular embodiment each of the plurality of paddles is arranged with a separation distance 226 from the cylindrical chamber wall of less than 3 mm, preferably less than 2 mm.

[0040] As schematically illustrated in figure 3, the continuous paddle mixer 220 may comprise a cylindrical mixing chamber with a cylindrical chamber wall, a first end242 and a second end 243. The cylindrical mixing chamber may be provided with an inlet 227 at the first end 242 and an outlet 228 at the second end 243. The provision of an inlet 1 1 at the first end 242 and an outlet 228 at the second end243 is generally preferable to providing the inlet 1 1 and the outlet 228 in the cylindrical chamber wall, as the former allow for more homogeneous heating conditions inside the mixing chamber 221. More specifically, the provision of an inlet 227 at the first end 242 and an outlet 228 at the second end 243 allows the cylindrical mixing chamber to be provided with a heating means 241 on the outside of, or in the wall of the cylindrical mixing chamber that may itself be cylindrically symmetrical or be connected to heating elements that is cylindrically symmetrical, e.g. heating jacket or similar. The continuous paddle mixer 220 may thus allow for homogeneous heat transfer along the full length of the mixing chamber 221 to a pre-mixed blend undergoing paddle mixing. Heating means 241 may here for example be resistive heating, oil-based heating, induction heating etc. In the example where the heating means are resistive heating, the resistive heating may for example be evenly distributed on the outside of the mixing chamber or in the wall of the mixing chamber 221. Electrical resistive heating is preferable, for example relative to oil-based heating, as electrical resistive heating has a lower fire hazard and thus lower requirements related to environment, health and safety. The inlet 227 may be arranged such that feeding of the pre-mixed blend into the mixing chamber 221 may be assisted by gravity.

[0041] Figure 3 schematically illustrates a continuous paddle mixer 220 where the plurality of paddles 223 are arranged to provide continuous paddle mixing along the full length of the mixing chamber 221. Continuous paddle mixing along the full length of the mixing chamber 221 may generally be obtained if anylongitudinal segment of the mixing chamber 221 is covered by at least one paddle 223. As each paddle 223 generally may have an extension in the longitudinal direction 224 of the shaft 222, the continuous paddle mixer 220 may be provided with at least N paddles 223 with a blade with a width B, such that the length L of the mixing chamber is such that L < N*B. The continuous paddle mixer 220 may thus in a particular example comprise at least N paddles 223 with equal width B such that L = N*B. As will be appreciated by a person skilled in the art, the continuous paddle mixer 220 may generally comprise various types and number of paddles 223. Several paddles 223 may for example be provided symmetrically along the shaft 222. Continuous paddle mixing along the full length of the mixing chamber 221 is generally preferred in order to limit build-up of material at either end and / or at various positions inside the mixing chamber 221. The paddles 223 may be arranged on the shaft 222 in one or more rows. The number of rows of paddles may for example be 2, 4, 6 or 8.

[0042] Each paddle may generally according to the present invention comprises a blade having a width B in the range 20 - 100 mm. The blade of a paddle may be the part of the paddle being furthest from the shaft. The blade, i.e., the shape of the blade may be linear, or alternatively be curved. In a particular embodiment, one or more of the paddles may have a blade with a width in the range 25 - 50 mm, most preferably in the range 30 - 35 mm. Blades with a width of 30 - 35 mm has been found to be preferable when the mixing chamber is 20 cm in diameter, for example in order to balance centrifugal forces of the continuous paddle mixer under operation.

[0043] The method for agglomerating coke particles may according to the present invention be performed continuously. More specifically, the continuous paddle may be continuously fed with the pre-mixed blend, and may thus continuously produce a paddle mixed blend. The method for agglomerating coke particles may employ a plurality of carbonizers per continuous paddle mixer, where each of the carbonizers for example may be operated in batch mode while the continuous paddle mixer operates continuously. A suitable redirection system may thus be installed between the continuous paddle mixer and the plurality of carbonizers in order to transport the paddle mixed blend from the continuous paddle mixer to any one of the carbonizers.

[0044] According to a particular embodiment of the present invention the coke particles and the binder may be introduced into the pre-mixer in powder form. The latter allows for even starting conditions for the method according to the present invention as both the coke particles and the binder may be prepared / acquired according to predetermined properties. Pre-mixing coke particles and binder indry-form is also preferable in order to reduce the requirement for maintenance of the pre-mixer, as a dry premix i.a. will result in a reduced stiction in the premixer. A dry form may herein generally be considered as a substance with a moisture level of less than 3 %, preferably less than 1 %, and more preferably less than 0,1 %.

[0045] Figure 3 schematically illustrates a continuous paddle mixer 220 that comprises an inlet 227, and where the inlet 227 is provided with a cooler 229. Said cooler 229 may here be employed in order to avoid stiction of the pre-mixed blend to the inlet 227 as the pre-mixed blend enters the mixing chamber 221. As the continuous paddle mixer 220 generally is operated at elevated temperatures, any inlet 227 of the mixing chamber 221 may reach an elevated temperature that may be sufficient to cause softening of the binder in the pre-mixed blend and thus stiction of the pre-mixed blend to the inlet 1 1 of the mixing chamber 221. The inlet 1 1 of the mixing chamber 221 may optionally, or additionally be provided with a low stiction coating 244 on the inside. The low stiction coating 244 may be chosen from the group of polytetrafluoroethylene coating, chlorotrifluoroethylene coating, polychlorotrifluoroethylene coating and tetrafluorethylene-perpfluoropropylene coating.

[0046] In an example, the method according to the present invention may be performed by introducing dry coke particles and pitch into a pre-mixer followed by premixing the coke particles and the pitch into a pre-mixed blend. The ratio between the coke particles and the pitch may here be 20: 1, with the D50 particles sizes of the coke particles and the pitch being 11 micron and 4 micron respectively. From the pre-mixer, the pre-mixed blend may subsequently be transported at a rate of 100 kg / hour into a continuous paddle mixer pre-heated to 230 °C, where a given portion of the pre-mixed blend may be heated and paddle mixed into paddle mixed blend over a period of 1 minute. The continuous paddle mixer may comprise a cylindrical mixing chamber with an diameter of 20 cm, a shaft arranged in the centre of the mixing chamber, and 12 paddles, each arranged on the shaft and with a distance to the mixing chamber wall of 2 mm. The continuous paddle mixer may be operated at a speed of 3000 rpm, resulting in a velocity of the tip of each paddle to be approximately 29 m / s. The paddle mixed blend may then be introduced into a carbonizer that is pre-heated to a temperature of 600 °C and be maintained as this temperature for 3 hours.

Claims

Claims1. A method (100) for agglomerating coke particles, the method (100) comprising pre-mixing (110) coke particles and a binder into a pre-mixed blend in a premixer (210), paddle mixing (120) the pre-mixed blend into a paddle mixed blend in a continuous paddle mixer (220), where the continuous paddle mixer (220) comprises a mixing chamber (221), a shaft (222), and a plurality of paddles (223) connected to the shaft (222) along the longitudinal direction (224) of the shaft (222), where at least one paddle is rotatably connected to the shaft (222) such that the angle (225) of the at least one paddle is adjustable, and carbonizing (130) the paddle mixed blend in a carbonizer (240), where, during paddle mixing (120), the continuous paddle mixer (220) is arranged such that the shaft (222) is aligned substantially horizontal, and where the pre-mixed blend is heated to a temperature of at least 80 °C.

2. The method (100) according to claim 1, where the method (100) comprises continuously feeding the continuous paddle mixer (220) with the premixed blend.

3. The method (100) according to any one of the preceding claims, where the mixing chamber (221) of the continuous paddle mixer (220) is cylindrical and comprises a cylindrical chamber wall, a first end and a second end, and where each of the plurality of paddles (223) is arranged with a separation distance (226) from the cylindrical chamber wall of less than 3 mm.

4. The method (100) according to claim 3, where the continuous paddle mixer (220) is provided with an inlet (227) at the first end and an outlet (228) at the second end.

5. The method (100) according to any one of the preceding claims, where the plurality of paddles (223) are arranged to provide continuous paddle mixing (120) along the full length of the mixing chamber (221).

6. The method (100) according to any one of the preceding claims, where each paddle comprises a blade having a width in the range 20 - 100 mm, preferably in the range 25 - 50 mm, most preferably in the range 30 - 35 mm.

7. The method (100) according to any one of the preceding claims, where the continuous paddle mixer (220) comprises an inlet (227) and where the inlet (227) is provided with a cooler (229).

8. The method (100) according to any one of the preceding claims, where each paddle is rotated by a speed in the range 25 m / s - 70 m / s measured at the tip of said paddle.

9. The method (100) according to any one of the preceding claims, where the coke particles and the binder are introduced into the pre-mixer (210) in powder form.

10. The method (100) according to any one of the preceding claims, where the residence time of any portion of the pre-mixed blend in the continuous paddle mixer (220) is less than 1 minute.

11. A system (200) for agglomerating coke particles, the system (200) comprises a pre-mixer (210) configured to pre-mix coke particles and a binder into a premixed blend, a continuous paddle mixer (220), comprising a mixing chamber (221), a shaft (222), a plurality of paddles (223) connected to the shaft (222) along the longitudinal direction (224) of the shaft (222), where at least one paddle (223) is rotatably connected to the shaft (222) such that the angle (225) of the at least one paddle (223) is adjustable, and a carbonizer (240) configured to carbonize the paddle mixed blend, where the continuous paddle mixer (220) is configured to paddle mix the premixed blend into a paddle mixed blend, to operate with the shaft (222) being aligned substantially horizontal, and to heat the pre-mixed blend to a temperature of at least 80 °C.

12. The system (200) according to claim 11, where the mixing chamber (221) of the continuous paddle mixer (220) comprises a chamber wall and where each of the pluralityof paddles (223) is arranged with an adjustable separation distance (226) from the chamber wall.

13. The system (200) according to claim 12 or 13, where the mixing chamber (221) of the continuous paddle mixer (220) is cylindrical and comprises a cylindrical chamber wall, a first end and a second end, and where each of the plurality of paddles (223) is arranged with a separation distance (226) from the cylindrical chamber wall of less than 3 mm.

14. The system (200) according to any one of the claims 11 - 13, where the continuous paddle mixer (220) is configured to rotate the shaft (222) such that each paddle (223) is rotated by a speed in the range 25 m / s - 70 m / s measured at the tip of the paddle (223).

15. The system (200) according to any one of the claims 11 - 14, where the continuous paddle mixer (220) comprises an inlet (227) and where the inlet (227) is provided with a cooler (229).

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