NL1004781C2 - Method and device for working up dust mixtures with at least two phases with different cooking temperatures. - Google Patents

Description

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Title: Method and device for working up dust mixtures with at least two phases with different boiling temperatures.

The invention relates to a process for working up dust mixtures with at least two phases with different boiling temperatures, including at least one heavy metal component from the group of cadmium and mercury, and for recovering at least one component from the phase with the higher boiling temperature by evaporation at a sub-atmospheric pressure in a vacuum chamber, and by separate condensation of the phases, in particular for the recovery of the heavy metals from the aqueous phase of electrolytic power sources.

Such substance mixtures, which consist of at least 50% by weight of solids and / or the liquid mercury and cannot be processed by a single operation, occur, for example, but not exclusively, with returned old batteries such as mercury batteries and nickel cadmium batteries containing a metal housing, an electrolyte with electrolyte water and a heavy metal such as mercury, and / or a heavy metal compound such as cadmium hydroxide. The latter two substances in particular are highly toxic and dangerous for the environment, which is why strict regulations exist to dispose of those substances. In addition, such batteries contain plastic sealing material and / or casings. All these components have different vapor pressures and boiling temperatures, which can be represented by so-called vapor pressure curves.

The plastics eligible for this purpose can be decomposed into easily volatile components (hydrocarbons) and high molecular weight solids by rising temperatures and falling pressures, whereby the easily volatile components can be evaporated and condensed, and the high molecular weight components 3 ·] - 2 - to remain in the residues of the dust mixture, where they are converted to carbon at appropriate temperatures. The non-toxic metals such as, for example, iron and zinc, also remain in the dust mixture, which at the end of the treatment process forms in a vacuum chamber a so-called "cake".

Such extremely inhomogeneous substance mixtures can only be separated with great difficulty into their individual components, the more so since their decomposition products and evaporable components can be separated from one another only with great difficulty. Hence there has been no lack of attempts, for example, to reprocess or render harmless the highly dangerous mercury batteries by thermal, physical and chemical processes.

It is known from DE 32 43 813 C2 to process batteries containing mercury by heating the batteries in a first process stage at a pressure of 0.95 bar under rinsing with an inert gas at 200 ° C and thereby opening them and in the 20 batteries as sealing material existing plastic components partially decomposes. The danpen formed therein, which also contain part of the mercury, are fed into an afterburner with the supply of air and combustion gas, in which the decomposition products of the plastic are burned at temperatures between 1500 and 2000 ° C. The off-gases from the afterburner are led into a cooling vessel in which the mercury is condensed. In a second process step, the battery debris is heated to 415 ° C, the remaining plastic components being decomposed and the decomposition products thereof also passed through the afterburner with a further amount of the mercury.

The mercury is also condensed in the cooling vessel, in a third process step the battery residues are heated to 510 ° C and the residual amounts of mercury are expelled by a pulsating pressure between 0.5 and 0.05 bar. Quantities of mercury leaving the cooling vessel are finally collected in a special cold trap.

- 3 -

The known method itself is cumbersome and time consuming and its energy balance is unfavorable because the inert and heated purge gas is passed through the entire device, but in particular because large quantities of fuel gas and combustion air must be supplied, which after heating up to 2000 ° C into the cooling vessel, which is subjected to a high thermal load. This gas is also dragged by the entire device, so also by the cold trap, which is hereby also subjected to a high thermal load, so that in both mercury capacitors not only the condensation heat of the mercury is released, but also the heat energy of the large quantities of gas carried away carried away. In addition, the mercury vapors necessarily heated at high temperature by the afterburner are extremely aggressive towards most metals because they lead to the formation of amalgam. Nothing has been said at all about the residence of the necessarily electrolyte water. No data are also provided on the processing of cadmium-containing substance mixtures.

From DE 44 02 499 Cl it is known for a contaminated solvent bath, i.e. a liquid, with components from the group formed by water, low-boiling substances and hydrocarbon solvents from cleaning methods for textiles, leather, fur, sheets, workpieces, electronic parts, etc. subjecting to vacuum distillation and supplying, by means of a temperature-dependent conversion, alternately to a first condenser for water and low-boiling substances with a first vacuum pump and to a second condenser for solvent gases with a second vacuum -30 pump and the non-evaporated residues to a finishing treatment, a very homogeneous temperature distribution prevails in the liquid due to a continuous movement by the boiling process. The temperature is measured in the vapor space above the liquid and therefore only shows the actual value for the fraction which has just evaporated, which means that the temperature measurement starts with the value for the lowest boiling component in each case, and that for a multitude of components, the transitions are smooth.

The evaporation, condensation and recovery of toxic heavy metals with significantly higher group 5 boiling points of mercury and cadmium from an irreversible bed of solids or sludge has not been treated.

US 4 401 463 discloses a pyrolysis process for the recovery of metals from old batteries with a supply of 3 to 12% oxygen without using a vacuum, in which the batteries are first reduced, the scrap is dried in a preheater by hot air and preheated and freed from organic components at temperatures up to 500 ° C in a subsequent pyrolysis oven. Here, the metallic cadmium necessarily transitions into its oxide form. The gases formed in this process are afterburned in a special oven. By raising the temperature to about 900 ° C and using a reducing atmosphere with hydrogen, the cadmium oxide is again reduced to cadmium and then distilled off. Finally, the cadmium vapor is condensed and poured into blocks. Not only are the organic components lost here, but the environment is also polluted by the combustion and heating gases, the combustion gases being passed through a venturi washing device to remove the chlorine present from the electrolyte vapors. The nickel remains in the extremely hot residues, which are exposed to an air stream provided for drying to recover heat. Nickel and other metals oxidize under strong heat development to form dust oxides. The nickel oxide, which is highly carcinogenic in dust form, also ends up in the atmosphere with the drying air, which is no longer permitted today. A temperature measurement to control the device differently does not take place.

The method is very cumbersome, not only in terms of equipment but also in terms of energy, and leads to a heavy burden on the environment.

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The object of the invention, on the other hand, is to provide a method of the nature described in the beginning, in which neither an inert purge gas, nor fuel gas and combustion air are required, and wherein the 5 components with the different cooking temperatures are reliable and inexpensive as well as energy-saving. and be separated from each other without burdening the environment. In addition, the pipes do not risk to be blocked by condensates.

Especially with heavy metals, including toxic components such as mercury and cadmium, which have the higher boiling temperatures, a clean recovery of these heavy metals will be possible in terms of equipment and environment.

In the initially indicated method according to the invention the solution of the stated objective takes place in that in the absence of oxygen a) the dust mixture is continuously measured in the dust mixture at an initial pressure of less than 100 mbar and in a temperature range in the absence of oxygen. wherein at least predominantly only the phase with the lower boiling temperature evaporates, the evaporated phase condenses in a condenser and the condensate is collected in a closable device, 25 b) when the temperature variation in the dust mixture changes due to the freedom of the residual dust mixture of the lower boiling temperature phase closes said device opposite the first capacitor, and c) further treating the residual dust mixture at further elevated temperatures, thereby treating at least one of the higher boiling temperature phases including at least one heavy metal component from the group of cadmium and kw I, expels in vapor form and the vapor condenses.

Due to the present measures, the dust mixture used can be disassembled very reliably, especially at low pressures and temperatures, into the separate components resp. phases and / or component or phase groups. Purging gases as well as combustion gases and combustion air are required as little as high combustion temperatures, so that the condensation surfaces connected after the vacuum chamber 5 are not burdened by large quantities of waste gases. Nor does the increased peak reactivity temperatures of the evaporated components vis-à-vis parts of the device result from the significantly lower peak temperatures of the process operation than in the prior art. This results in an unambiguously more favorable energy balance and nevertheless the individual components can be reliably separated from one another, possibly even by further purification.

Essential here is the temperature measurement in the load 15 itself, which is not reversible, and preferably in the middle of the load, because the coldest zone is located there. Namely, the heating takes place from the furnace mantle, namely via the edge zones of the load. Since the switchover only takes place when the coldest zone has also reached the boiling or evaporating temperature associated with the respective pressure, it is ensured that the components which can be evaporated below the switching point can also evaporate without leaving any residue.

On the other hand, because of the absence of oxidation, the temperatures of the charges cannot assume higher values than the controlled temperature of the furnace heating, so that evaporation takes place carefully, which is very favorable with organic substances. No pyrolysis takes place and no harmful substances, for example no chlorine compounds and no dioxins can be released, so that it is also not necessary to wash the waste gases wet.

In the presence of the higher boiling phase (s) in the form of a hydroxydic or oxidic metal compound, it is particularly advantageous if this compound is evaporated after its dissociation and / or reduction to its respective metal and condensed on a metal condenser.

- 7 - connected up to the capacitor for the condensation of the phase with the lower boiling temperature.

In the presence of mercury in the dust mixture of a mercury battery, it is particularly advantageous to first evaporate only the electrolyte water at a first temperature and condense it in a condenser, which is designed as a liquid condenser and is connected to the device via a shut-off valve, and that after the water evaporation has ended, the shut-off valve is closed, the temperature of the residual dust mixture is increased, the mercury is evaporated and condensed on the same condenser.

In this case, the mercury is obtained practically quantitatively in the condenser, while the electrolyte water is condensed in the device and the cake-shaped residue from the used substance mixture with all non-evaporated and non-evaporable components remains in the vacuum chamber.

In the presence of cadmium hydroxide in the dust mixture, it is particularly favorable if 20 a) a capacitor for the electrolyte water is used and a liquid condenser is connected to it, b) first only the free electrolyte water evaporates and condenses in the capacitor, 25 c) after evaporating the free electrolyte water further increases the temperature of the residual dust mixture, such that the cadmium hydroxide is dissociated into cadmium oxide, d) the water from the dissociation process condenses in the condenser, e) a reducing gas from the group to the cadmium oxide of hydrogen and hydrocarbons, thereby leaving the cadmium and evaporating the reaction water and condensing again in the condenser, f) collecting the total condensation water in the plant and closing it opposite the condenser, and when finally 1 004 '. - 8 - g) further decreases the underpressure and further increases the temperature, thereby evaporating the cadmium and condensing the cadmium vapor in the metal condenser.

Here again, the highly toxic cadmium is obtained practically quantitatively in the metal condenser, while the electrolyte water and the further formed reaction water are in the closed device and the unvaporised and non-evaporable residues of the used dust mixture remain in the vacuum chamber.

Further favorable embodiments of the present method are evident from the other method claims.

The invention also relates to a device for carrying out the present method with a heatable vacuum chamber, a condenser, at least one vacuum pump device connected to this afterwards, as well as with at least one temperature sensor for determining the temperature of the dust mixture and of the dry mass .

For solving the same task, such a device according to the invention is characterized in that the capacitor is connected to a device via a shut-off valve, and that the temperature sensor is connected to the shut-off valve via a control unit, the control unit being designed in this way that the shut-off valve is closed as soon as the temperature sensor detects that the temperature measured in the dust mixture rises after the water evaporation has ended.

Insofar as there are metals in the substance mixture, either in an elementary state such as, for example, mercury, or in the form of a hydroxydic or oxidic compound, which must first be dissociated and reduced to elemental metal, such as, for example, cadmium, it is particularly favorable if between the vacuum chamber and the condenser are fitted with a metal capacitor, which is connected to a circuit with a circulation pump, a heating device, a cooler and a control device, which is designed such that by switching from heating to cooling the condensing surfaces of the metal capacitor at 0 0 4 ·.

- 9 - the passage of non-metallic vapors is set at such a temperature that no condensation of the non-metallic vapors takes place and that the condensation surfaces are set at 5 temperatures when metal vapors enter, during which metal condensation takes place.

A particularly advantageous process operation then becomes possible when a switching valve is placed in the cycle between the heating device and the cooler, whereby the liquid fed into the cycle can optionally be passed through the cooler via a bypass line.

Two exemplary embodiments of the object of the invention are explained in more detail below with reference to Figures 1 and 2.

Herein: Fig. 1 shows a process scheme for recovering mercury from mercury batteries, and Fig. 2 shows a modified process scheme for recovering cadmium and nickel from nickel-cadmium battery.

Fig. 1 shows a heatable vacuum chamber 1, which has a door 2 and a heat-damping jacket 3. This contains, for example in a basket, a load 4 of a non-reversible dust mixture, in the center of which a temperature sensor T protrudes. A pressure sensor P is used to register the pressure inside the chamber. The charge 4 is heated from the outside, which means that either the vacuum chamber 1 is provided with a heating device, or a heating device (not shown) is arranged between the inner wall of the vacuum chamber 1 and the charge 4. As a result, the coldest zone of the load 4 is located in the middle of the load 4 during heating.

A suction line 5 leads from the vacuum chamber 1 to a condenser KI with condensation surfaces 6. The bottom of the

capacitor KI is through a pipe with a shut-off valve VI

1 0 0 4? Q 1 - 10 - connected to a device Bl, which has a discharge valve 7.

from the condenser K1 leads a suction line to a pump system 9 with a Roots pump 10, an intermediate pump 11 and 5 a water ring pump 12. Water ring pump 12 includes a water circuit with a return cooler K2 and a water separator 13, which is connected via a line 14 with a drain is connected. If necessary, a gas purifier (not shown), such as an absorber, can be switched in, in which decomposition products are separated from the plastic.

The vacuum chamber 1 is first driven at a temperature of the wall or heater below the boiling temperature given at the given process pressure (eg 42.4 mbar) so that no mercury evaporates. The temperature of the load cannot therefore exceed the relevant temperature of the wall or heating device. The electrolyte water is first condensed in the capacitor K1, which is transferred to the device B 1. As soon as a temperature rise at T indicates that the residual dust mixture is at least largely anhydrous in the middle as well, the shut-off valve VI is closed by means of the control unit 15. The temperature of the charge is now raised and the pressure is further reduced, so that the boiling temperature of the mercury is exceeded. This is now condensed quantitatively in the capacitor K1. Evaporative decomposition products of the plastic gaskets of the batteries are also separated in the liquid capacitor K1. The high molecular weight decomposition products and the carbon of the plastic seals and the other metals of the batteries remain in the dry mass, the so-called "cake", in the vacuum chamber and are worked up separately. No oxygen is supplied to the vacuum chamber 1.

In Fig. 2, the same parts as in Fig. 1 are indicated by the same indications, so that repetitions are superfluous. In this case, however, the capacitor K1 has an I / V; metal capacitor K3 with a condensing surface 16 upstream, which includes a cooling circuit 17 with a circulation pump 18, a heating device 19, a control device 20 and a cooler 21. However, the cooler 21 can be optionally passed by the control device 20, a changeover valve 22 and a bypass line 23.

Here, the capacitor KI also serves to condense the electrolyte water, in three stages. First, the free electrolyte water is expelled and condensed at a temperature and a pressure as described in FIG. Then the temperature of the charge is raised to, for example, 400 ° C, whereby the cadmium hydroxide is converted into cadmium oxide. The originally bound electrolyte water released in this process is condensed in this second stage, in the third stage the temperature of the charge is increased to 500 ° C and a reducing gas from the group of hydrogen and hydrocarbons is supplied, whereby the cadmium oxide is reduced to metallic cadmium. The reaction water thus formed and the slightly liquid decomposition products of the sealing material of the batteries are also condensed in the capacitor K1. The total amounts of condensate are now in the Bi device. As soon as the temperature sensor T indicates by temperature rise that the remaining charge is anhydrous, the control unit 15 closes the shut-off valve VI.

The control device 20 of the control unit 15 is now commanded via a control line 24 to switch the cooling circuit 17: while previously the condensation surface 16 was kept at a temperature of, for example, 80 ° C, so that no water could condense, the temperature thereof is now lowered to, for example, 20 ° C, whereby the cadmium in the metal capacitor K3 is quantitatively separated. The nickel remains together with other metals such as e.g. iron, 35 and the high molecular weight decomposition products of the plastic and with formed carbon in the remaining charge, the so-called cake, in the vacuum chamber 1, on which

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- 12 - the second embodiment is still discussed. In this case, too, oxygen is not supplied to the vacuum chamber 1 at any time during the process.

Example 1 (mercury materials): In a device according to Fig. 1 with a volume of the vacuum chamber of 0.2 m3, 100 kg of uncompleted old batteries with an amount of mercury of 0.7 kg and an amount of electrolyte water of 9 kg were placed in the vacuum chamber and it was first pressurized to 23 mbar. A pressure of 42.4 mbar and a temperature of 40 ° C were then set without supply of oxygen. The water evaporated, but not the mercury. 8.6 kg of water were condensed in the capacitor KI and transferred to the device B1 in about 480 minutes. The temperature of the substance mixture was kept constant by suitably controlled heating. The batteries opened automatically when the water evaporated. When the water evaporation ended, the temperature in the residual dust mixture started to rise. This was observed by the temperature sensor placed in the center of the dust mixture, after which the control unit 15 closed the shut-off valve VI. Then, without supply of oxygen, the pressure was lowered to 10'2 mbar and the temperature was raised to 300 ° C by the heater within 140 minutes, whereby the mercury gradually evaporated and also condensed in the condenser K1. After 90 minutes, only a dry mass of 88.8 kg with a residual mercury content of 1.7 mg per kg of dry mass remained, which was mechanically reduced. The iron present was sorted out with a magnetic peeler and added to normal steel scrap in a steel company. The manganese dioxide and zinc dust present were processed in a zinc smelter.

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Example 2 (nickel cadmium materials):

In a device according to Fig. 2 with a volume of the vacuum chamber of 0.015 m3, 10 kg of unopened old batteries with an amount of cadmium of 2.1 kg, an amount of nickel of 2.0 kg and an amount of electrolyte water of 1.8 kg into the vacuum chamber 1 and it was first evacuated at 20 mbar. Then, without oxygen supply, a pressure of 20 mbar and a temperature of 50 ° C were set. The water evaporated, but not the cadmium and also the nickel. In about 120 minutes, 1.65 kg of electrolyte water were condensed in the capacitor KI and transferred to the device B1. Subsequently, the temperature was raised to 400 ° C without supply of oxygen, so that the cadmium bound as hydroxide dissociated and was converted into cadmium oxide. A further 0.15 kg of reaction water were evaporated and condensed in the capacitor KI and transferred to the device B1. The temperature was then adjusted to 500 ° C, and methane was added to the residual dust mixture as the reducing gas for the duration of 60 minutes, until the cadmium oxide had been reduced to metallic cadmium. The water of reaction thus formed was also evaporated and condensed in an amount of 0.2 kg in the capacitor K1 and transferred to the device B1. Here too, the batteries opened automatically when the water evaporated. The temperature set by the evaporation of the water in the dust mixture by heating was continuously measured, and at the beginning of an additional temperature rise as a sign of the anhydrous dry mass, the device B1 was closed by the valve V1 opposite the capacitor K1. . Finally, the pressure was lowered to 10'2 mbar and the cadmium was evaporated under gradual temperature increase to 700 ° C and condensed in the metal capacitor K3. 2.1 kg of 1004781-14 cadmium were recovered. The cadmium content in the dry mass was thus 5.6 mg per kg of dry mass.

The metal condenser K3 was operated by means of the connected circuit 17 with the control device 20 so that the condensation surfaces 16 of the metal condenser K3 were set at a temperature of 80 ° C at the passage of the water vapor through the heating device 19, without condensation of water occurred, and that the condensation surfaces 16 were adjusted to a temperature of 20 ° C through the cooler 21 upon entering the cadmium vapors 10, with a quantitative condensation of the cadmium. Uzer and nickel remained in the dry mass and were reprocessed in a stainless steel processing plant.

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Claims (12)

A method for working up dust mixtures of at least two phases with different boiling temperatures, including at least one heavy metal component from the group formed by cadmium and mercury, and recovering at least one component from the phase with the higher boiling temperature by evaporation at sub-atmospheric pressure in a vacuum chamber (1), and by separate condensation of the phases, in particular for the recovery of the heavy metals from the aqueous phase of electrolytic power sources, characterized in that absence of oxygen a) treats the dust mixture under continuous temperature measurement in the dust mixture at an initial pressure of less than 100 mbar and in a temperature range, wherein at least 15 mainly evaporates only the phase with the lower boiling temperature, condenses the evaporated phase in a condenser (KI) and collecting the condensate in a closable device (B1), b) upon a change in temperature course in the dust mixture due to the freedom of the residual dust mixture from the lower boiling temperature phase, closing said device (B1) opposite the first capacitor (KI), and c) further treating the residual dust mixture at further elevated temperatures and at least one of the higher boiling temperature phases, including at least one heavy metal component from the group formed by cadmium and mercury, expels in vapor form and condenses the vapor. Process according to claim 1, characterized in that in the presence of the higher boiling phase (s) in the form of a hydroxydic or oxidic metal compound, this compound is evaporated after dissociation and / or reduction to the respective metal and a metal capacitor (K3) 35 condenses, which is connected to the capacitor (K1) - 16 - for the condensation of the phase with the lower boiling temperature 3. Process according to claim 1, characterized in that in the presence of mercury in the dust mixture of a mercury battery, only the electrolyte water is first evaporated at a first temperature and condensed in a condenser (Ki), which is designed as a liquid condenser and via a the shut-off valve (VI) is connected to the device (B1), and that after the water evaporation has ended, the shut-off valve is closed, the temperature of the residual dust mixture is increased, the mercury evaporates and condenses on the same condenser (K1). Process according to Claim 2, characterized in that in the presence of cadmium hydroxide in the substance mixture a) a liquid condenser is used as the capacitor (K1) for the electrolyte water and a metal condenser (K3) is first connected to it, b) firstly the free electrolyte water evaporates and condenses in the condenser (Kl), 20 c) after evaporation of the free electrolyte water, the temperature of the residual dust mixture increases even further, such that the cadmium hydroxide is dissociated into cadmium oxide, d) the water from the dissociation process condenses in the condenser (K1), e) feeds a reducing gas from the group of hydrogen and hydrocarbons to the cadmium oxide, thereby leaving the cadmium and evaporating the reaction water and condensing again in the condenser (K1), 30 f) the total condensation water in the device (Bl) and seal it opposite the capacitor (Kl), and finally g) the negative pressure is further reduced. decreases and the temperature increases even further, thereby evaporating the cadmium and condensing the cadmium vapor in the metal condenser (K3). Method according to claim 4, characterized in that the condensation surface of the metal condenser (K3) is kept at a temperature during the evaporation of the water, at which the water is not condensed, and that after the evaporation of the water and at the beginning of the evaporation of the cadmium the temperature of the condensing surface of the metal capacitor (K3) is set to a value, the cadmium condensing quantitatively. 6. Method according to claim 3, characterized in that the pressure during evaporation of the electrolyte water is adjusted to 10 between 20 and 50 mbar, preferably between 40 and 45 mbar, after closing the valve (VI) opposite the capacitor (K1) lowers the pressure to a value below 20 mbar, preferably in the range below 1 mbar, preferably from 10-2 mbar, and evaporates the mercury while increasing the temperature of the residual dust mixture and in the condenser (Kl) condenses. 7. Process according to claim 6, characterized in that the temperature of the residual dust mixture to form a practically mercury-free dry mass under vacuum is raised to a maximum of 400 ° C, preferably to a maximum of 300 ° C. Process according to claim 4 for the recovery of cadmium from electrolyte-containing nickel-cadmium batteries, characterized in that a) the pressure is evaporated between 20 and 50 mbar, preferably between 40 and 45 mbar, when the free electrolyte water evaporates. , and sets the temperature below 100 ° C, b) subsequently, to dissociate the cadmium hydroxide, increase the temperatures to values above 100 ° C to 400 ° C, 30 c) then reduce the cadmium oxide by means of a reducing gas from the group of hydrogen or hydrocarbons to cadmium under a further temperature rise to 500 ° C, d) measures the temperature which settles on evaporation in the dust mixture, and with a temperature rise the device (Bi) through the valve (V1) opposite the condenser (Kl), and finally 1004781 - 18 - e) before evaporating the cadmium, pressurize values below 20 mbar, preferably in the range below 1 mbar, preferably from 10'2 mbar, lowers and the cadmium evaporates under temperature increase and condenses in the metal-5 capacitor (K3). Process according to claim 8, characterized in that the temperature of the residual dust mixture is increased under vacuum to a maximum cadmium-free dry mass under vacuum to a maximum of 800 ° C, preferably to a maximum of 10 700 ° C. Device for carrying out the method according to at least one of claims 1 to 9, with a heatable vacuum chamber (1), a condenser (KI), at least one downstream vacuum pump device (9), and with at least one temperature sensor (T) for determining the temperature of the dust mixture and the dry mass, characterized in that the capacitor (KI) is connected via a shut-off valve (V1) to a device (B1), and that the temperature probe (T) is connected to the shut-off valve (V1) via a control unit (15), the control unit (15) being designed in such a way that the shut-off valve (V1) is closed as soon as the temperature sensor (T) establishes that the dust mixture temperature rises after the water evaporation has ended. Device according to claim 10, characterized in that a metal condenser (K3) is placed between the vacuum chamber (1) and the condenser (KI), which asm a circuit (17) with a circulation pump (18), a heating device (19 ), a cooler (21) and a control device (20) are connected, which is designed such that by switching from heating to cooling, the condensation surfaces of the metal condenser (K2) pass through non-metallic vapors at such a temperature be adjusted so that no condensation of the non-metallic vapors takes place and that the condensation surfaces are set at temperatures when metal vapors enter, at which a metal condensation takes place. 10 0 47 S1 - 19 - Device according to claim 11, characterized in that a switching valve (22) is placed in the circuit (17) between the heating device (19) and the cooler (21), as a result of which the liquid fed into the circuit is optionally provided via a bypass line on the cooler (21) can be passed. L b L; .