Method for machining hard metals

Abstract

The present invention relates to a method for processing hard metals, more particularly hard metal scrap, in which: the hard metals are alloyed with a low-melting alloying metal in a reaction chamber of a reactor (10) while heat is applied; the alloying metal is then converted into a gaseous phase in the presence of an inert gas; the alloying metal is subsequently at least partially condensed in a condensation step; and the reaction chamber is at a positive pressure relative to ambient pressure, at least during the condensation phase. More particularly, according to the invention, inert gas is continuously supplied to the reaction chamber from an inert gas source (60) outside the reaction chamber via an inert gas supply line (61) at least temporarily during the condensation phase, and the inert gas is released to the environment from a condenser (30) at least during several phases of the condensation phase. In this way, the plant complexity can be significantly reduced compared to hard metal decomposition methods known in the prior art.

Description

Technical Field

[0001] The present invention relates to a process for processing hard metals, particularly hard metal scrap, where the hard metal is alloyed with a low melting point alloy in the reaction space of a reactor under the supply of heat, and then the alloy is converted into the gas phase in the presence of an inert gas, and subsequently, the alloy is condensed in a condensation step.

Background Art

[0002] Such a process is known from German Patent Invention No. 31 44 284 C2. For this purpose, several crucibles are stacked within the receiving space. The crucibles hold the hard metal scrap and the zinc material to be processed. The receiving space is sealed from the environment and connected to a vacuum line connected to a vacuum pump. To process the hard metal material, the receiving space is first evacuated to remove internal oxygen. Subsequently, an inert gas, such as argon, is injected into the receiving space, and then the receiving space is heated to melt and introduce the zinc material into the liquid phase. The zinc material diffuses into the hard metal matrix and reacts with the cobalt of the hard metal material. In this way, the hard metal is alloyed. When the cobalt material reacts with the zinc material, reaction products are formed and the volume significantly increases. The increase in volume breaks the bond between the carbide hard material phase and the metal binder. Subsequently, zinc can be distilled in the condensed phase and separated in the condenser. For this, the temperature in the receiving space is increased until the zinc evaporates. The vaporous zinc material flows into the condenser together with the inert gas. In the condenser, the zinc material is condensed and the inert gas flows back to the hard metal. Therefore, the zinc vapor can be absorbed here again, resulting in a closed circuit. To enable the maintenance of the flow in this circuit, a delicate pressure gradient is set between the receiving space containing the hard metal and the condenser using a vacuum pump. This requires a significant amount of equipment. In particular, the sealing of the receiving space, as well as the use and control of the vacuum pump, considerably affect the cost. Furthermore, complex system control is required.

[0003] After the condensation phase is complete, a porous, hard metal structure remains in the receiving space, which can be ground into a fine powder for reuse. Similarly, the condensed zinc material can be used in a new recycling process. [Overview of the project] [Problems that the invention aims to solve]

[0004] This invention addresses the problem of creating the type of process described earlier, which can be used to significantly reduce the cost and effort of the necessary equipment. [Means for solving the problem]

[0005] This problem is solved by continuously supplying an inert gas to the reaction space via an inert gas supply line from an inert gas source located outside the reaction space, at least temporarily, during the condensation phase, and by releasing the inert gas from the condenser into the environment at least at regular intervals during the condensation phase.

[0006] According to the present invention, the reaction space is continuously flushed with an externally supplied inert gas during the condensation phase. In relation to the present invention, flushing can be carried out continuously throughout the condensation phase. However, flushing may also be carried out at intervals. It is important that the externally supplied inert gas passes over the hard metal to be processed during the condensation phase, where the inert gas absorbs the vaporized zinc material. The zinc material is then routed to the condenser in vapor form, where it can be separated. Thus, the mass flow created by the temperature gradient between the high-temperature and low-temperature ends is supported by the inert gas flow. The inert gas, without zinc material, then leaves the condenser. The inert gas can be expanded to the ambient pressure outside the reactor and condenser and released into the environment. The inert gas may also be returned to the reaction space, thus increasing the pressure. This can be done, for example, using a suitable pump. According to the present invention, continuous flushing is carried out at an overpressure compared to the ambient pressure in the reaction space. In this way, a vacuum pump is not required. According to the present invention, since operating conditions in a vacuum, i.e., operating conditions of negative pressure relative to the environment, are not required, there is no need to satisfy stringent requirements for sealing the reaction space from the environment. In particular, the present invention eliminates the formation of an initial vacuum, which was required in the prior art to remove oxygen from the reaction space. Rather, according to the present invention, an inert gas is used to flush the air out of the reaction space and to remove it in the first phase thanks to a pressure reduction to ambient pressure. This can be monitored, for example, by an air sensor, particularly an oxygen sensor. Once sufficient oxygen has been removed from the reaction space, the reaction space is heated, and hard metals can be alloyed with alloying materials.

[0007] According to the present invention, an excess pressure relative to the ambient pressure in the range of 1 mbar to 90 mbar can be provided. The plant can operate safely at this pressure.

[0008] As described above, according to the present invention, in the flushing phase, an inert gas is introduced into the reaction space from an inert gas source, where the inert gas replaces the air present in the reaction space, and this is discharged into the environment through a closable opening, and the opening is subsequently closed again. A pressure valve may be used to constitute the closable opening. In particular, it may be a regulated pressure valve connected to a control device. In this regard, an air sensor, such as an oxygen sensor, connected to a control device may be provided, where the signal pickup of the air sensor is preferably located in the reaction space, in a condenser, or in another gas transport area of ​​the plant.

[0009] In a particularly preferred modification of the present invention, a vapor mixture containing an inert gas and zinc vapor may be provided, which is discharged from the reaction space via a vapor pipe and routed to a condenser via a heating pipe to which a heater is assigned. This heater assigned to the heating pipe is preferably provided and can be operated separately from a heating device that heats the reaction space. In this way, the heating level in the heating pipe can be directly influenced so as to reliably prevent or clearly cause zinc condensation in the heating pipe.

[0010] The process according to the present invention may be designed such that the main amount of zinc condenses and collects in a condenser. A separator may be used to separate any residual zinc in the inert gas stream. The separator ensures that any zinc material in the form of vapor is not removed from the condenser and condensed in downstream plant components. In particular, according to the present invention, the separator may be used to carry out at least a phased release of the inert gas stream from the condenser to the environment during the condensation phase. The separated zinc material may be collected separately or preferably returned to the condenser to feed into previously collected condensed zinc material.

[0011] A further modification of the present invention provides one or more receptacles arranged in a reaction space, each containing a receiving space for containing a hard metal, a receptacle including at least one flow channel, or at least one flow channel assigned to a receptacle, a flow channel forming a spatial connection between the receiving space and a gas transport area of ​​a reactor located outside the receiving space, and an exhaust channel extending from the provided receiving space, wherein an inert gas is supplied through at least one flow channel, and together with the gas phase alloy, the inert gas is released from the receiving space. This constitutes a considerable advantage over solutions known from the prior art as specified in German Patent Invention No. 31 44 284 C2, in which no flow channels are provided, but rather only connection paths in the form of capillaries. The purpose of these capillaries is to prevent zinc vapor from entering the gas transport area from the receiving space. The inventors recognized that, due to the guidance of the flow of inert gas according to the present invention, a flow channel may be provided instead of a capillary, through which a large volume of flow can enter the receiving space. This creates a far more effective flow into the receiving space. The flow channel is preferably designed so that a line of sight is possible from the receiving space through the flow channel to the gas transport area in order to reduce flow resistance to the flow.

[0012] Within the scope of the present invention, in particular, at least 1 mm 2 ~30mm 2 A cross-section of the flow channel can be provided.

[0013] The containment vessels, crucibles, steam piping, and / or collection containers are preferably made of a material inert to zinc vapor, such as graphite or ceramic.

[0014] Therefore, if a housing is provided that includes a bottom and surrounding walls rising from there, and a wall having a notch in its rim facing outward when viewed from the bottom, the notch forming a flow channel, the housing can be easily manufactured.

[0015] According to the present invention, several containers are stacked such that their discharge channels are aligned with one another, and a line section of steam piping is provided that is transported along a path through the aligned discharge channels, where a channel remains between the outer wall of the line section and the discharge channel for releasing the gas phase of the alloy from the receiving space of the containers. The steam piping facilitates the structural assignment of the individual containers to each other. Furthermore, the mixture of inert gas and vaporized zinc transported in the channel heats the steam piping during the condensation phase, ensuring that condensation within the steam piping is prevented. In addition, the selected arrangement configuration achieves a compact design.

[0016] If a line section of an inert gas supply line opening into the upper region of the reaction space, and a line inlet of a steam pipe positioned within the reaction space at a geodetic height below the opening of the inert gas supply line are provided, then at the beginning of the machining process, air present in the reaction space can be effectively moved out of the reaction space by the delivery of the target gas along the path.

[0017] The condenser has a simple structure when it is provided, which includes a cup-shaped collection container, the top of which is airtightly closed by a removable cover, and the end of a steam pipe inserted into a through-hole in the cover.

[0018] The present invention will be described in more detail below based on exemplary embodiments shown in the drawings. [Brief explanation of the drawing]

[0019] [Figure 1] This shows a cross-sectional view of a plant used for processing hard metals, seen from the side. [Figure 2] Shows a perspective view of the container. [Figure 3] Shows a cross-sectional view of the container taken from the side of the container in FIG. 2. [Figure 4] Shows details of the portion indicated by IV taken from FIG. 3. [Figure 5] Shows details of the portion indicated by V in FIG. 3.

Mode for Carrying Out the Invention

[0020] FIG. 1 shows a processing plant according to the invention which can be used for processing hard metals, particularly hard metal scrap. The processing plant includes a reactor housing 10 having a crucible 14. The crucible 14 can be shaped like a cup. The crucible includes a bottom at the bottom from which walls rise. At its upper end, the crucible 14 forms an opening which can be closed by a cover 17. When the cover 17 is removed, the crucible 14 can be loaded with the container 20, as will be described in detail later.

[0021] The crucible 14 is surrounded in at least some regions by a heating device 15 having heating elements 15.1. The heating elements 15.1 can be formed by known resistance heaters.

[0022] The cover 17 includes a through-hole 17.1 through which a steam pipe 11 is introduced into the reaction space surrounded by the crucible 14. Further, the cover 17 has a second through-hole 17.2. An inert gas supply line 61 opens in the region of this second through-hole 17.2. A heat insulating material 16 is provided laterally of the heating device 15 and the heat insulating material can be made of refractory bricks. Further heating elements 15.2 are arranged above the cover 17. A heat insulating material 16, for example made of refractory bricks, is arranged above these further heating elements 15.2.

[0023] The inert gas supply line 61 is sent along a path and connected to an inert gas source 60. The inert gas source 60 can be, for example, a high-pressure inert gas reservoir where the inert gas is preferably argon.

[0024] A control device not shown in FIG. 1 can be used to control the flow of the inert gas fed by the inert gas source 60 in the inert gas supply line 61. In particular, this control device includes a pressure reducer and a volume flow controller.

[0025] <^ One line section 62 of the inert gas line 61 leads to the reaction space surrounded by the crucible 14. Preferably, as shown in FIG. 1, the end section 63 of the line section 62 is sent along a path through the through-hole 17.2 of the cover 17.

[0026] The steam pipe 11 has a line inlet 11.1 located in the region of the bottom of the crucible 14. From this line inlet 11.1, a line section 11.2 is sent vertically upward through the cover 17 from the reaction space along a path. The line section 11.2 transitions to a heating pipe 11.3. The heating pipe 11.3 is sent along a path to the end portion 11.4 of the steam pipe 11. The end portion 11.4 has an outlet port 11.5. This outlet port 11.5 opens into the condenser 30.

[0027] The condenser 30 is preferably in the form of a collecting container 31 and is cup-shaped. The collecting container 31 has a bottom from which walls rise. In its upper region, there is a cover 32 that closes the collecting container 31. The end portion 11.4 of the steam pipe 11 is sent along a path through this cover 32.

[0028] As can be seen from FIG. 1, a heating device 33 having one or more heating elements 33.1 is assigned to the collecting container 30. The heating element 33.1 is designed as a resistance heater. The heating element 33.1 is covered laterally, for example, by a heat insulating material made of refractory bricks.

[0029] The heating pipe 11.3 is assigned to a heater 50. This heater 50 surrounds the heating pipe 11.3 in at least some areas and is positioned along at least a portion of the length of the heating pipe 11.3. The heater 50 may be used to generate heat and transfer it to the heating pipe 11.3.

[0030] Figure 1 further shows that the reactor 10 may include a separator 40. This separator 40 is preferably assigned to the condenser 30. The separator 40 is spatially connected to a collection space surrounded by a collection container 31. The separator includes condensing surfaces, which are not shown in detail in the drawings. These condensing surfaces are part of the guide area of ​​the separator 40. Furthermore, the separator 40 includes an inert gas discharge line 42.

[0031] As described above, the containers 20 can be stacked in the reaction space of the crucible 14. For this purpose, the containers 20 are sized so that they can be inserted into the reaction space when the cover 17 is removed. Preferably, all containers 20 are of the same design to reduce the number of different parts required.

[0032] Figure 2 shows that the containment 20 includes a bottom 21, from which the surrounding walls 22 rise. The walls 22 include a rim 22.1 that faces outward when viewed from the bottom 21. A notch is made in the rim 22.1 to form a flow channel 23. It is also conceivable that the walls 22 have apertures that form the flow channel 23.

[0033] The bottom 21 includes a line section 24 that protrudes from the bottom 21 in the same direction as the wall 22. As shown in Figure 3, the line section 24 forms a discharge channel 25 that passes through the containment 20. Therefore, the upper end of the discharge channel 25 facing outward when viewed from the bottom 21 forms a channel opening 25.1. Another channel opening 25.2 of the discharge channel 25 is provided in the region of the bottom 21.

[0034] Figure 4 shows that the channel opening 25.1 is recessed from the rim 22.1 toward the bottom 21. Figure 4 further shows that a recess 27 may be provided in the upper rim of the line section 24.

[0035] Figure 5 shows a cross-section of the flow channel 23. As shown in this embodiment, the flow channel 23 is preferably in the shape of a rectangular notch or aperture. They have a width B and a depth T.

[0036] The flow cross-sectional area of ​​flow channel 23 is 1-30 mm². 2 The following applies:

[0037] The containment 20 is preferably made of graphite.

[0038] The housing 20 has an inner circumferential surface 21.1 and an outer circumferential surface 26. The inner surface 21.1 and the outer surface 26 are spaced apart from each other, forming an upper annular rim.

[0039] The bottom portion 21, together with the inner surface 21.1 and outer surface of the line section 24, defines the boundary of the receiving space.

[0040] The lower surface 21.2 of the base 21 has shoulders 21.3 on the rim. These shoulders 21.3 can be used to align and stack the containers 20 with each other. As a result, the shoulders 21.3 of the upper container 20 rest on the rim 22.1 of the container 20 directly below it. Therefore, the containers 20 are fixed to each other in the direction of the plane of the base 21 so that their shapes fit together perfectly.

[0041] The container 20 is sealed by the container 20 placed above it, where the bottom 21 of the upper container 20 is placed on the rim 22.1 of the lower container 20 in a sealing manner. In this way, a receiving space is formed at the bottom of the container 20, which is spatially connected to the outer surface 26 and the adjacent area via the flow channel 23. Furthermore, the discharge channel 25 is used to spatially connect this receiving space to the discharge channel 25 of the upper container 20 located above it, and to the discharge channel 25 of the lower container 20 located directly below it. This is made possible, in particular, because the upper rim of the line section 24 is slightly recessed and / or a recess 27 is provided in the line section 24, as shown in Figure 4.

[0042] As shown in Figure 1, multiple containers 20 can be stacked in the reaction space as described above, where the discharge channels 25 of each container 20 are interaligned. The bottom 21 of the lowest container 20 rests on the support surface of the crucible 14. A collection area is formed below the bottom 21 of the lower container 20 in the crucible, where the line inlet 11.1 is located. A lid 28 may be used to close the upper container 20.

[0043] As shown in Figure 1, the steam pipe 11 is routed through mutually aligned discharge channels 25. Therefore, the remaining cross-section is formed as a channel 12 between the outside of the steam pipe 11 and the line section 24 that forms the discharge channels 25.

[0044] The operating principle of reactor 10 is described in more detail below. First, individual containers 20 are filled with hard metal material and zinc material to be machined. The containers 20 are then stacked in the reaction space of crucible 14. Next, steam piping 11 is inserted into the aligned discharge channel 25 until the line inlet 11.1 reaches the bottom region of crucible 14. A cover 17 may then be used to close crucible 14.

[0045] A gas transport region 13.1 is formed between the outer surface 26 of the containment 20 and the inner wall of the crucible 14. This gas transport region 13.1 is spatially connected to the deck-side supply region 13, and an inert gas supply line 61 also opens there. When the cover 17 is in place and the upper end insulation material 16 is applied, the inert gas source 60 is opened. As a result, the inert gas flows from the inert gas source 60 through the inert gas supply line 61 into the reaction space.

[0046] The air in the reaction space is moved from top to bottom, where the inert gas flows through the gas transport area 13.1 and the flow channel 23 into the receiving space of the containment 20. In this way, the air is moved out of the receiving space and guided through the channel 12 towards the line inlet 11.1 of the steam pipe 11. Furthermore, the air in the gas transport area 13.1 is moved towards the line inlet 11.1. The air then flows through the steam pipe 11 into the condenser 30.

[0047] The separator 40 has a valve, which is open. Therefore, air can be moved away from the condenser 30. The air flows from the separator 40 to the environment via the inert gas discharge line 42 or other discharge point.

[0048] As soon as the air is removed from the plant, the valve is closed again. Then the preheating phase in the first heating phase begins. A heating device 15 is used to raise the reaction space to a temperature above the solidus temperature of the zinc material. The zinc material liquefies and diffuses into the hard metal matrix. In this process, the zinc material reacts with the cobalt in the hard metal matrix. When the cobalt material reacts with the zinc material, reaction products are formed, significantly increasing the volume. This increase in volume breaks the bond between the carbide hard material phase and the metal binder. This alloying process can take several hours. After the alloying process is complete, preferably when all the cobalt has reacted with the zinc material, a second heating phase occurs. In the second heating phase, the temperature of the reaction space in the crucible 14 is further raised to the temperature at which the zinc material evaporates. If an inert gas is supplied from the inert gas source 60 through the inert gas supply line 61 into the reaction space, the inert gas flows through the flow channel 23 into the receiving space of the containment 20. The gas transport region 13.1 ensures that all receiving spaces are filled as uniformly as possible with inert gas. For this purpose, the sum of the cross-sections of the flow channels 23 is preferably less than or equal to the cross-section of the inert gas supply line 61. The inert gas takes in the gaseous zinc material in the receiving spaces of the containment 20 and supplies it to the discharge channel 25. In the discharge channel 25, a mixture of inert gas and zinc vapor is carried through channel 12 toward the bottom of the crucible 14. As a result of the continuous inflow of inert gas from the inert gas source 60, an overpressure is created relative to the pressure in the collection container 31 of the condenser 30. This helps to force the gas mixture out of the reaction space through the vapor piping 11.

[0049] The vapor mixture flows into the collection container 31 via the heating pipe 11.3. The heating device 15 prevents the zinc material from the zinc vapor from condensing within the region of the heating pipe 11.3. This ensures that the zinc material enters the collection container 31 in the gas phase.

[0050] The heating device 33 of the condenser 30 is used to set a temperature level such that the zinc material condenses and collects in the collection container 31. In this way, the heating device 33 controls the temperature so that, if possible, the zinc material is collected in liquid form in the condenser 30.

[0051] The continuous inflow of inert gas into the reaction space also increases the pressure in the condenser 30. A pressure valve is provided to prevent excessive back pressure from building up in the collection container 31. When the upper threshold is reached, this pressure valve opens to release the inert gas from the collection container 31 into the environment. Preferably, the pressure valve is part of the separator 40. When the pressure in the collection container 31 drops again to the lower threshold, the pressure valve closes again. The inert gas exits the separator 40 via the inert gas release line 42.

[0052] A temperature sensor is preferably assigned to the steam pipe 11. This temperature sensor directly or indirectly measures the temperature of the gas mixture as it is transported along the path through the steam pipe 11. High temperatures are generated in the heating pipe 11.3 as long as zinc vapor is taken into the inert gas flow through the steam pipe 11. High temperatures are generated in the heating pipe 11.3. If the amount of zinc taken into the inert gas flow decreases, the temperature in the heating pipe 11.3 decreases. If the temperature decreases, the heater 50 introduces additional heat into the heating pipe 11.3 to prevent the zinc from condensing. The temperature decrease can be used to determine whether zinc material is still being transported from the container 20. If no more zinc material is being transported away, the system may preferably be swept away using an inert gas, after which the process may be completed in a controlled manner.

[0053] Finally, the separated (split) hard metal may be removed from the container 20 and sent for further processing. For example, the hard metal may then be ground in a suitable mill. It may then be reused to produce a new hard metal body. The process according to the present invention may be used to recycle hard metal with a residual zinc content of less than 50 ppm.

[0054] According to the present invention, a process is provided for processing hard metal scrap, in which the hard metal is alloyed with a low-melting-point alloy, such as zinc, in the reaction space of a reactor 10 by applying heat. The resulting alloy is then converted to a gas phase in the presence of an inert gas, so that the alloy is at least partially condensed in a condensation step. The process is carried out such that there is an excess pressure in the reaction space compared to the ambient pressure, at least during the condensation phase. During the condensation phase, the inert gas is supplied to the reaction space at least temporarily from an inert gas source 60 located outside the reaction space via an inert gas supply line 61. Furthermore, in this manner, during the condensation phase, the inert gas is released from the condenser 30 into the environment at least at regular intervals.

Claims

1. 1. A process for processing hard metals, in particular hard metal scrap, in which the hard metals are alloyed with a low-melting-point alloy in a reaction space of a reactor (10) under the supply of heat, after which the alloy is converted into the gas phase in the presence of an inert gas, and the alloy is subsequently at least partially condensed in a condensation step, and an overpressure relative to the ambient pressure exists in the reaction space at least during the condensation stage, 1. A process according to claim 1 , characterized in that the inert gas is permanently supplied to the reaction space from an inert gas source (60) located outside the reaction space via an inert gas supply line (61) at least temporarily during the condensation stage, and that the inert gas is released from a condenser (30) to the environment at least at certain intervals during the condensation stage.

2. 2. The process according to claim 1, characterized in that the overpressure relative to ambient pressure ranges from 1 mbar to 90 mbar.

3. 3. The process according to claim 1 or 2, characterized in that in the flushing stage, an inert gas is introduced from the inert gas source into the reaction space, wherein the inert gas replaces the air present in the reaction space, and this air is discharged to the environment through a closable opening, and subsequently the opening is closed again.

4. 4. The process according to claim 1, wherein the vapor mixture comprising the inert gas and zinc vapor is discharged from the reaction space via a vapor line (11) and routed to the condenser (30) via a heating line assigned to a heater.

5. 5. The process according to claim 4, characterized in that the inert gas discharged from the condenser (30) is expanded to ambient pressure or the inert gas discharged from the condenser (30) is compressed by a compressor and recycled to the reaction space.

6. 6. The process of claim 4 or 5, characterized in that the inert gas is routed from the condenser (30) to a separator (40), and in that the inert gas in the separator (40) flows past a condensing surface of the condenser (30) to separate any remaining zinc residues from the inert gas.

7. 7. The process according to claim 4, wherein one or more containers (20) are arranged in the reaction space, each of which comprises a receiving space for receiving the hard metal, wherein the containers (20) comprise at least one flow channel (23) or at least one flow channel (23) is assigned to the containers (20), wherein the flow channel (23) forms a spatial connection between the receiving space and a gas conveying area (13.1) of the reactor (10) located outside the receiving space, and wherein a discharge channel (25) is provided which is routed out of the receiving space, such that an inert gas is fed via the at least one flow channel (23) and is discharged from the receiving space together with the alloy present in the gas phase.

8. 8. The process according to claim 7, characterized in that the container (20) comprises a bottom (21) and a peripheral wall (22) rising therefrom, and that the wall (22) comprises a cut-out in a rim (22.1) facing away from the bottom (21), which cut-out forms the flow channel (23).

9. The cross section of the flow channel (23) is 1 mm ２ ~30mm ２ 9. The process according to claim 7 or 8, characterized in that it comprises:

10. 10. The process according to any one of claims 7 to 9, characterized in that several containers (20) are stacked so that the discharge channels (25) of the containers (20) are aligned with one another, and that line sections (11.2) of the steam pipe (11) are routed through the aligned discharge channels (25), wherein a channel (12) is left between an outer wall of the line section (11.2) and the discharge channel for discharging the gas phase of the alloy from the receiving space of the container (20).

11. 11. The process according to any one of claims 4 to 10, characterized in that the line section (62) of the inert gas supply line (61) opens into the upper region of the reaction space, and that the line inlet (11.1) of the steam pipe (11) is located in the reaction space at a geodetic altitude below the opening of the inert gas supply line (61).

12. 12. The process according to any one of claims 4 to 11, characterized in that the condenser (30) comprises a cup-shaped collecting vessel (31), the end (11.4) of the steam pipe (11) opens into the condenser (30), and the line inlet (11.1) of the steam pipe is located in the reaction space at a geodetic height below the opening of the steam pipe (11).

13. 7. The process according to claim 6, characterized in that a pressure valve is provided which establishes a connection between a gas conveying region and the environment or the circuit line, and when a pressure threshold is reached in the gas conveying region, the pressure valve opens and releases inert gas to the environment or the circuit line, wherein the pressure valve is arranged downstream of the separator (40).

14. Apparatus for carrying out the process according to any one of claims 1 to 13.

Images