DE102009059016A1 - Treating free-flowing grain from inorganic raw material, comprises continuously supplying grain to heated treatment chamber over grain inlet and then heating the grain in it, and exposing treatment gas flowing between gas inlet and -outlet - Google Patents

Abstract

The method comprises continuously supplying the grain to a heated treatment chamber (2) over a grain inlet (7) and then heating the grain in it, exposing a treatment gas flowing between a gas inlet (9) and a gas outlet (10), transporting to a grain outlet by a gravitational force and then continuously discharging from the treatment chamber, and transporting the grain as a granular layer to a first chute, which is arranged within the treatment chamber, over a partial section between the grain inlet and the grain outlet, where the first chute ends at a transfer opening above the grain outlets. The method comprises continuously supplying the grain to a heated treatment chamber (2) over a grain inlet (7) and then heating the grain in it, exposing a treatment gas flowing between a gas inlet (9) and a gas outlet (10), transporting to a grain outlet by a gravitational force and then continuously discharging from the treatment chamber, and transporting the grain as a granular layer to a first chute, which is arranged within the treatment chamber, over a partial section between the grain inlet and the grain outlet, where the first chute ends at a transfer opening above the grain outlets. The granular layer has a minimum thickness of less than 3 cm, and is transferred over the transfer opening to a second chute that is arranged within the treatment chamber and contrarily extends itself to the first chute within the treatment chamber. The grain inlet lies in an upper opening plane and the transfer opening lies in a lower opening plane. A connecting line between the grain inlet and the transfer opening encloses with the horizontals to a contact angle, which is as larger as a specific repose angle of the grain. The first chute has a sliding surface, which encloses with the horizontals to a cascade angle, which is as larger as the specific repose angle of the grain. The contact angle or the cascade angle is maximum 5[deg] larger than the specific repose angle of the grain. The treatment gas flows through the treatment chamber from bottom to top and through the transfer opening. The treatment gas is a chlorine-containing reaction gas and the grain in the treatment chamber receives a retention time of 30 minutes. An independent claim is included for a treatment module for treating a free-flowing grain from an inorganic raw material.

Description

The present invention relates to a method for the treatment of flowable granules of inorganic raw material by the grain continuously fed via a grit inlet to a heated treatment chamber, heated therein while exposed to a flowing between a gas inlet and a gas outlet, treatment gas, and transported by gravity to a Körnungsauslass and is continuously discharged from the treatment room.

The invention furthermore relates to a treatment module suitable for carrying out the method for treating free-flowing granules of inorganic raw material, having a heatable treatment space which has a granulation inlet in an upper region and a granulation outlet in a lower region, and a gas inlet and a gas outlet for a treatment gas.

State of the art

Mineral raw materials can be freed from impurities such as iron, titanium, alkali metals and alkaline earth metals by treatment under a chlorine-containing atmosphere at high temperature (thermochlorination). For the thermochlorination different methods and reactors are used, which are essentially fluidized bed, rotary kiln and shaft furnaces.

Fluidized bed ovens are used in particular for ore processing and are suitable for high material conversions. In the EP 1 098 846 B1 Such a cleaning method is also proposed for the purification of a raw material of quartz granules. In this case, a bed of grain is flowed through in a reactor from bottom to top of chlorine-containing treatment gas, which is introduced via a plurality of nozzle openings, which are distributed over a large area. The bed is slightly raised by the flow of the treatment gas to form a so-called "fluidized bed". Reactor and gas shower are made of quartz glass.

By this procedure, a largely uniform treatment of the grain is ensured; However, it may come to a segregation of fine dust due to an air view effect. The known method is also suitable only for discontinuous operation.

This disadvantage avoids the continuous purification of crystalline quartz powder by thermochlorination in a rotary kiln, such as in the EP 737 653 A1 described. It is proposed to supply the quartz powder to be cleaned to an electrically heated rotary kiln in which it successively passes through a preheating chamber, a reaction chamber and a gas desorption chamber. In this case, metallic impurities of the quartz powder react with the chlorine-containing treatment gas to form volatile metal chlorides. The treatment gas and the gaseous reaction products are sucked off.

The thermochlorination in a rotary kiln also leads to a uniform treatment intensity of the grain and high grain fineness can be achieved. However, the cleaning of ultrafine powders and dusts is not readily possible because they are easily discharged with the gas stream. The rotary kiln has a large space requirement and the rotating components of the furnace are subject to considerable wear. In addition, it comes through frontally open ends of the rotary kiln to a considerable heat radiation.

The two last-mentioned disadvantages avoids the shaft furnace method for continuous cleaning of free-flowing quartz sand, as for example from the DD-PS 144 868 is known. The quartz sand to be cleaned is fed continuously from above to the vertically oriented shaft furnace. Due to its own weight, the silo-like quartz sand bed gradually passes through the furnace from top to bottom, passing through a warm-up zone, a thermochlorination zone and a cooling zone. These zones are designed as filling funnel-like, closed containers, which are arranged one above the other and connected to each other via an inlet or an outlet for the quartz sand. The treatment gas is introduced via a line in the center of the bed in the lower part of the container, which forms the Thermochlorierzone. In order to prevent the penetration of oxygen into the Thermochlorierzone and thus prevent the regression of the resulting during chlorination of volatile chlorides in solid metal oxides, a gas curtain of inert gas is generated at the entrance and exit area.

The shaft furnace is relatively simple in construction and has no moving parts. However, because of its heat-insulating effect, heating the granulation pad from the outside to the inside takes a long time and forces a relatively slow throughput. The procedure also does not lead to a sufficiently reproducible purity of the grain, which can be attributed to different treatment intensities within the silo-like granulation in the thermochlorination zone, which results from uneven distribution of the treatment gas and by a pronounced silo flow in the bulk due to flow edge effects.

One of these standard methods fundamentally different method for the purification of SiO ₂ grain by thermochlorination is from the DE 198 13 971 A1 known. Therein it is proposed to disperse the SiO ₂ grain to be cleaned in a fuel gas flame containing a chlorine-containing fuel gas component. The purified SiO ₂ granules and the gaseous reaction products are introduced directly into a cyclone and separated from each other.

Technical task

The invention has for its object to provide a method that allows a reliable and reproducible treatment of free-flowing inorganic grain, in particular the purification of particularly finely divided mineral resources, with low consumption of treatment gas.

Furthermore, the invention has for its object to provide a compact and flexible reactor as possible for performing the method.

With regard to the method, this object is achieved on the basis of a method of the type mentioned in the introduction, that the grain is transported over at least a section between Grannungseinlass and Körnungsauslass as a grain layer on a disposed within the treatment room first chute, which ends at a transfer opening above the Körnungsauslasses ,

In the modification of the known shaft furnace method according to the invention, the grain is not exposed to the treatment gas in a silo-like, vertical bed within the reaction vessel, but it trickles due to their flowability along a slope to form a grain layer of comparatively small thickness through at least a portion of the treatment space. As a result of this movement and because of the comparatively small thickness of the graining layer on the chute, a comparatively large graining surface is available to the treatment gas, which enables a uniform and effective treatment of the grain and thus, for example, a high degree of purity. The movement of the grain occurs due to their flowability and their own weight. Moveable mechanical parts are not required.

In that regard, the invention combines the advantages of rotary kiln and shaft furnace method while avoiding their disadvantages.

The grain gradually flows in the form of the granulation layer from the granulation outlet via the transfer opening in the direction of the granulation outlet and is treated with the treatment gas. On the slide, a bed forms with a grain-specific angle of repose. Depending on the "slope" of the chute, the thickness of the grain layer is substantially constant, or it decreases from top to bottom, or it increases from top to bottom. The grain-specific angle of repose depends, for example, on the grain size, grain size distribution, morphology and chemical composition of the grain. As a rule, the grain-specific angle of repose decreases with the mean grain size.

The chute extends between the grit inlet and the transfer opening. It is in the simplest case a plate inclined to the vertical; However, it may also be formed, for example, half-shell-shaped. Even with a horizontal orientation of the chute, a bed with the grain-specific angle of repose arises between the grain outlet and the transfer opening, but in this case, there are still or poor-moving grain areas within the grain layer. The chute can also run helically within the treatment room. All that is essential is that a granulation layer with the specific angle of repose forms on the chute and between the grain outlet and the transfer opening.

The treatment gas is, for example, a chlorine-containing gas, as is otherwise used in the prior art for the purification of mineral bulk material, a doping gas for doping the grain, or a flushing gas such as hydrogen or helium for exchange with another adsorbed on the graining surface gas. During the treatment with the treatment gas, the grain is heated to a high temperature within the treatment space, for example to a temperature above 800 ° C.

Inorganic graining is quartz sand of naturally occurring raw material, synthetic quartz glass grain, SiC grain or graphite and the like.

The granulation passes through the transfer opening into a region of the treatment space arranged below the first slide. In this space may be arranged another slide for receiving the granulation layer, or it is a free space which opens into the granulation outlet and in which the granulation can be poured up and removed via the granulation outlet.

In the method according to the invention thus results in at least two granulation beds within the treatment chamber, of which a bed on the first slide and a further bed below the first slide are formed.

It has been shown that, due to this procedure, within the treatment space with a relatively low layer thickness of trickling granulation, a rapid heating of the granulation and a uniform and effective treatment can be achieved. This contributes to the fact that the granulation layer can be heated from all sides, especially from below. The process is continuous and therefore also advantageous from a productivity point of view.

The thinner the granulation layer is formed on the chute, the higher the treatment effect, in particular a cleaning effect. Therefore, a procedure is preferred in which the granulation layer above the transfer opening has a minimum thickness of less than 5 cm, preferably a minimum thickness of less than 3 cm.

From the transfer opening, the layer thickness either decreases or increases in the direction of the grain inlet in accordance with the grain-specific angle of repose. The minimum thickness of the graining layer, due to the ratio of addition and removal of the grain, will either be above the transfer port at or below the grain inlet, depending on the slope of the first chute. Ideally, the removal of the grain is such that a minimum layer thickness approaches zero.

At the transfer opening there is a bridging between the bed on the first slide and the area below it.

In a preferred variant of the method, it is provided that the granulation layer is transferred via the transfer opening to a second chute disposed within the treatment space, which extends opposite to the first chute within the treatment space.

In this embodiment, at least two slides are arranged within the treatment space, which form a cascade with one another, for example by running zigzag or meandering within the treatment space. At the transfer opening, the granulation layer passes from the first, upper chute to the second, lower chute. The respective granulation layers are connected via a granulation bridge which extends through the transfer opening. The second chute ends at the grain outlet or at another transfer opening, so that one or more further chutes can be arranged in cascade manner below the second chute.

Due to this spreading of the grain in the form of a cascade-like grain layer extending within the treatment space, a particularly high surface area and an effective treatment effect result, even at high throughputs.

This contributes to the fact that the graining layer has underside grains resting on the first chute and a free upper side, the graining layer being turned over from the first to the second chute in such a way that at least part of the undersize grains come to rest on the free upper side. The "turning" of the graining layer at the transition from the first, upper chute to the lower chute additionally contributes to the homogenization of the reaction with the treatment gas.

In order to ensure optimal trickling of the grain over the granulation layer, it has proven useful if the granulation inlet in an upper opening plane and the transfer opening lie in a lower opening plane, wherein the connecting line between Grazernseinlass and transfer opening with the horizontal includes a plant angle that is at least as large is like a specific angle of repose of the grain.

This ensures that a grain charge with the grain-specific angle of repose can form between the grain inlet and the transfer opening. Otherwise, it may slow down the trickle or backwater. The connecting line between the granulation inlet and the transfer opening results as a connection between the intersections of the respective opening plane and the opening center line.

A large installation angle has the advantage that one and the same treatment module can be used for a large number of different grain sizes and grain-specific angles of repose. On the other hand results in plant angles that are much larger than the grain-specific angle of repose, an unnecessarily high bed and thus a comparatively poorer treatment and cleaning effect. Therefore, a procedure is preferred in which the installation angle is adapted to the grain-specific angle of repose, such that the contact angle by a maximum of 10 °, preferably a maximum of 5 °, greater than the specific angle of repose of the grain. In the case of a quartz glass grain size typical angle of repose in the range of 25 to 36 degrees, so that plant angles up to 46 degrees, preferably a maximum of 41 degrees prove to be particularly favorable.

In a particularly preferred procedure, it is provided that the first chute has a sliding surface which encloses with the horizontal a cascade angle which is at least as great as a specific angle of repose of the grain.

In this procedure, the slope of at least the first chute is greater than the grain-specific angle of repose. This results in the formation of a graining layer which is thin in the region of the grain inlet and which increases downwards according to the grain-specific angle of repose, and is largest at the transfer port. The large cascade angle has the advantage that the grain on the chute can not rest stably, but trickles away. As a result, areas with little movement are avoided within the granulation layer, which contributes to a more uniform treatment. It is also particularly advantageous that the treatment room can be emptied completely of grain even without tilting.

For this it is sufficient if the cascade angle is slightly larger than the grain-specific angle of repose. On the other hand, at cascade angles, which are significantly greater than the grain-specific angle of repose, an unnecessarily high bed and thus a comparatively poorer treatment and cleaning effect. Therefore, a procedure is preferred in which the cascade angle is adapted to the grain-specific angle of repose, such that the contact angle is greater than the specific angle of repose of the grain by a maximum of 10 °, preferably a maximum of 5 °.

It has proven particularly useful if the treatment gas flows through the treatment space from bottom to top and through the transfer opening.

The treatment gas is guided over at least a partial section within the treatment chamber in countercurrent to the movement of the granulation layer. This results in a particularly effective treatment effect.

This applies in particular to the granulation layer in the region of the transfer opening. Because there, the treatment gas is forcibly passed simultaneously with the opposite grain through the transfer opening, so that it comes to a particularly intimate contact and thus to an effective treatment, in particular an effective cleaning. In this context, it has proved to be advantageous if the opening width of the transfer opening has a maximum of 20 mm. The maximum opening width determines the layer thickness of the granulation layer in the region of the transfer opening.

It has proven useful if the treatment gas is a chlorine-containing reaction gas and the grain in the treatment room undergoes a residence time of at least 30 minutes.

The throughput through the treatment room determines the mean residence time of the granulation. For different areas of the graining layer, however, different treatment periods result. The grain areas with minimal residence time can be easily determined empirically. The throughput is to be adjusted on the basis of this finding so that a minimum residence time of 30 minutes or longer results. In the case of cleaning the grain using a chlorine-containing reaction gas usually results in a sufficient cleaning effect.

With regard to the reactor, the object stated above, starting from a reactor of the type mentioned in the introduction, is achieved by a first chute extending at least over a partial section between the grain inlet and the grain outlet in the treatment space, which ends at a transfer opening above the grain outlet.

The treatment module is part of a cleaning system. It replaces the treatment room in the known shaft furnace. In a modification to this, at least one chute is provided in the invention within the treatment space, which serves to receive a granulation layer which is moved downwards along a slope due to the flowability of the granulation and is thereby exposed to a treatment gas. The graining layer has a small thickness compared to the known silo-like vertical bed, so that a uniform treatment of the granulation with the treatment gas, prevents silo, and thus enables effective treatment. Movable mechanical parts are not required because the movement of the grain is due to their flowability and their own weight.

In that regard, the invention combines the advantages of rotary kiln and shaft furnace while avoiding their disadvantages.

The chute extends between the grit inlet and the transfer opening. It is in the simplest case a plate inclined to the vertical; However, it may also be formed, for example, half-shell-shaped. Even with a horizontal orientation of the chute is between the grain inlet and the transfer opening a bed with the specific grain for the angle of repose, However, this results in motionless or low-motion grit areas within the granulation layer. The chute can also run helically within the treatment room.

The treatment chamber can be heated to a high temperature by means of a heating device, for example to a temperature above 800 ° C., preferably above 1200 ° C.

In the region of the treatment space below the transfer opening, a further chute for receiving the granulation layer can be arranged, or it is a free space, which is connected to the grain outlet, and in which the grain is heaped up and can be removed via the grain outlet.

Advantageous embodiments of the treatment module of the invention will become apparent from the dependent claims. Insofar as in the subclaims specified embodiments of the treatment module, the procedures mentioned in subclaims for the method according to the invention are modeled, reference is made for supplementary explanation to the above statements on the corresponding method claims. The remaining modifications are discussed in more detail below.

The transfer opening preferably has a maximum opening width of 20 mm.

The maximum opening width determines the maximum layer thickness of the granulation layer in the area of the transfer opening. Due to a small opening width, an intimate contact with the treatment gas results when it is forcibly passed through the transfer opening simultaneously with the counterflowing grain.

It has proved to be advantageous if the treatment space and the at least one slide consist of quartz glass.

Quartz glass is characterized by high mechanical resistance and temperature resistance and contributes little to an additional contamination of the grain to be cleaned; this applies in particular when the grain to be cleaned is quartz glass grains. A particular advantage of this construction is also the transparency of the quartz glass components, in that the grain size can be effectively heated by thermal radiation. For example, transparent walls of the treatment space allow the rapid heating of the grain from the outside and transparent chutes the heating of the granulation layer from all sides, especially from below.

The treatment module is suitable for connection with other components of the treatment device. In a particularly preferred embodiment, it is provided for this purpose that the treatment module has a lower side, which is provided with connection elements for grit inlet of at least one further treatment chamber.

The connectable treatment chamber can be a further treatment module, in particular a cleaning module for cleaning the grain, a desorption module by means of which gases, such as HCl or chlorine, adsorbed on the grain using a purge gas are removed, or it is at the treatment chamber around a cooling device or around an oven for melting the grain.

In the simplest case, the connection element is the grain outlet of the upper treatment module. This corresponds, for example via a ground joint, with the grain inlet of the treatment chamber.

embodiment

The invention will be explained in more detail with reference to an embodiment and a drawing. In detail shows in a schematic representation

1 A first embodiment of a cleaning module for carrying out the method according to the invention in a side view,

2 the cleaning module of 1 in a top view (without grain),

3 a second embodiment of a cleaning module for performing the method according to the invention, and

4 a third embodiment of a cleaning module for performing the method according to the invention.

This in 1 illustrated cleaning module 1 consists of a in plan view ( 2 ) round containers with an inner diameter of 30 cm made of quartz glass. The container 2 is completely sealed from the environment and from a heated oven chamber 16 surround.

Inside the container 2 are three slides 3 . 4 . 5 of quartz glass arranged in cascade to each other. At the slides 3 . 4 . 5 it is at an angle to the central axis 17 and oriented to the vertical quartz glass plates, with the inner wall of the reaction vessel 2 are welded. Of the Tilt angle of the plates is in 1 with α, it is for all plates 3 . 4 . 5 about 10 °.

The two upper slides 3 . 4 each end just before the opposite side wall of the container 2 leaving a circular segment-shaped transfer opening 6 with a maximum opening width of 5 cm. The lower slide 5 ends at a graining outlet 8th at the bottom of the container 2 that as a ball cut 19 is formed and to which a (not shown in the figure) cooling chamber is connected.

At the top of the container 2 is a grit inlet 7 intended. A gas inlet 9 is as in the opening of the grain outlet 8th protruding supply line formed of quartz glass, and as a gas outlet 10 is in the upper part of the container 2 a quartz glass tube passed through the container side wall gas-tight.

About the grit inlet 7 gets quartz sand 11 on the top chute 3 and forms on this a graining layer 18 with an angle of repose β (in 1 For reasons of a clearer representation, the corresponding vertex angle is drawn with the horizontal). The angle of repose β is specific to the particular quartz glass grain and in the exemplary embodiment is about 36 degrees.

The midline 12 the grain intake 7 intersects with the opening plane at a point P1, and the center line 13 the transfer opening 6 intersects in its opening plane at a point P2. The connecting line between P1 and P2 forms a plant angle γ with the horizontal. The plant angle γ is always greater than the grain-specific angle of repose β, and it is 40 degrees in the embodiment. The same installation angle γ is also between the upper transfer opening 6 and the lower transfer opening 15 , as well as between the lower transfer opening 15 and the upper opening plane of the grain outlet 8th realized. The thickness of the graining layer 18 above the respective transfer openings 6 . 15 is about 1 to 2 cm.

From the transfer opening 6 the grain gets 11 on the second slide 4 , The graining layer 18 It is turned in such a way that previously on the slide 3 overlying grain 11 on the slide 4 comes to rest on the surface. About the slide 4 the grain gets 11 to the transfer opening 15 and from there to the bottom slide 5 , wherein the granulation layer 18 is turned again.

The grain 11 when trickling through the container 2 along cascading grain layer 18 by means of the oven 16 heated to a temperature of about 1270 ° C. Because of the comparatively small thickness of the granulation layer 18 and the transparency of the container wall and the slides 3 . 4 . 5 is the graining layer 18 Heatable from all sides by heat radiation, so that the heating in a short time succeeds. Because of the encapsulation of the container 2 the heat losses by radiation compared to a rotary kiln are relatively low.

From below, via the gas inlet 9 , becomes countercurrent to the direction of movement of the granulation layer 18 , a chlorine-containing cleaning gas introduced into the container. This flows through the container 2 from bottom to top and reacts with impurities of the quartz sand grain 11 with the formation of volatile chlorides. Due to the comparatively large spreading surface of the grain 11 over the cascaded slides 3 . 4 . 5 , the small thickness of the graining layer 18 and the intimate contact of grain 11 and cleaning gas in the area of the transfer openings 6 and 15 results in a particularly uniform and effective cleaning effect.

The throughput through the cleaning module 1 depends on the removal of the grain 11 over the grain outlet 8th (or via downstream facilities). If the removal is stopped, the grain inflow is also automatically stopped, as the beds on the slides 3 . 4 . 5 can not build up steeper. In that regard, the cleaning module shows 1 a certain self-control. With continuous removal, the throughput is typically 20 kg / h and the minimum residence time of the grain at 60 min.

In the in the 3 and 4 schematically shown embodiments of the cleaning module are the same or equivalent components and components of the device designated by the same reference numerals.

In the embodiment of the cleaning module 21 according to 3 are on the ground 22 of the container 2 two sampling nozzles 23 . 24 for the grain 11 provided by the respective cleaning gas via the supply lines 26 . 27 made of quartz glass in the container 2 is initiated. The lowest slide 25 ends here at the central axis 17 , Because of their shorter length, it turns on the slide 25 a smaller layer thickness of the granulation layer 18 a, so that in this embodiment allows a slightly larger throughput with the same cleaning effect.

This in 4 illustrated cleaning module 41 also consists of a round top container with an inner diameter of 30 cm made of quartz glass. The container 2 is completely from the Environment completed and heated by a furnace chamber 16 surround.

Inside the container 2 are two slides 43 . 44 of quartz glass arranged in cascade to each other. At the slides 43 . 44 it is at an angle to the central axis 17 and oriented to the vertical quartz glass plates, with the inner wall of the reaction vessel 2 are welded. The angle of inclination of the plates is in 1 denoted by α and is 40 °. This angle is 4 degrees greater than the grain-specific angle of repose of the quartz glass grains to be cleaned.

The upper slide 43 ends just before the opposite side wall of the container 2 leaving a circular segment-shaped transfer opening with a maximum opening width of 5 cm. The lower slide 44 ends at a graining outlet 8th at the bottom of the container 2 ,

At the top of the container 2 is a grit inlet 7 intended. A gas inlet 9 is as in the opening of the grain outlet 8th protruding supply line formed of quartz glass, and as a gas outlet 10 is in the upper part of the container 2 a quartz glass tube passed through the container side wall gas-tight.

About the grit inlet 7 gets quartz sand 11 on the top chute 43 and forms on this a graining layer 45 with an angle of repose β (in 4 For reasons of a clearer representation, the corresponding vertex angle is drawn with the horizontal). The angle of repose β is specific to the particular quartz glass grain and in the exemplary embodiment is about 36 degrees.

The midline 12 the grain intake 7 intersects with the opening plane at a point P1, and the center line 13 the transfer opening 6 intersects in its opening plane at a point P2. The connecting line between P1 and P2 forms a plant angle γ with the horizontal. The plant angle γ is always greater than the grain-specific angle of repose β and also greater than the angle of inclination of the plates 43 . 44 α and he is in the exemplary embodiment 45 degrees. The same installation angle γ is also between the transfer opening and the upper opening plane of the granulation outlet 8th realized. The graining layer 45 has above the respective transfer openings or above the Körnungsauslasses 8th their largest thickness and each at the top of the slides 43 . 44 their smallest thickness, which is about 1 to 2 cm.

The grain 11 when trickling through the container 2 along cascading grain layer 45 by means of the oven 16 heated to a temperature of about 1270 ° C. Because of the comparatively small thickness of the granulation layer 45 and the transparency of the container wall and the slides 43 . 44 is the graining layer 45 Heatable from all sides by heat radiation, so that the heating in a short time succeeds. Because of the encapsulation of the container 2 the heat losses by radiation compared to a rotary kiln are relatively low.

From below, via the gas inlet 9 , becomes countercurrent to the direction of movement of the granulation layer 45 , a chlorine-containing cleaning gas in the container 2 initiated. This flows through the container 2 from bottom to top and reacts with impurities of the quartz sand grain 11 with the formation of volatile chlorides. Due to the comparatively large spreading surface of the grain 11 over the cascaded slides 43 . 44 the small thickness of the graining layer 45 and the intimate contact of grain 11 and cleaning gas in the area of the transfer openings results in a particularly uniform and effective cleaning effect.

The throughput through the cleaning module 1 depends on the removal of the grain 11 over the grain outlet 8th (or via downstream facilities). If the removal is stopped, the grain inflow is also automatically stopped, as the beds on the slides 43 . 44 can not build up steeper. In that regard, the cleaning module shows 1 a certain self-control. With continuous removal, the throughput is typically 20 kg / h and the minimum residence time of the grain at 60 min.

At the with a ball cut 19 provided grit outlet 8th is a (not shown in the figure) identical desorption connected, in which the on the grain 11 adhering cleaning gas is removed. For this purpose is through the gas inlet 9 the desorption chamber hydrogen into the container 2 initiated, which substitutes the adhering chlorine-containing reaction gas.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1098846 B1 [0004]
• EP 737653 A1 [0006]
• DD 144868 [0008]
• DE 19813971 A1 [0010]

Claims (17)

Process for the treatment of free-flowing granules of inorganic raw material by the granulation ( 11 ) via a granulation inlet ( 7 ) a heated treatment room ( 2 continuously supplied, heated therein and one between a gas inlet ( 9 ) and a gas outlet ( 10 ) and by gravity to a granulation outlet ( 8th ) and continuously discharged from the treatment room ( 2 ), characterized in that the grain ( 11 ) over at least part of the way between the granulation inlet ( 7 ) and graining outlet ( 8th ) as a graining layer ( 18 ; 45 ) on a first chute ( 3 ; 43 ) transported at a transfer opening ( 6 ) above the grain outlet ( 8th ) ends. Method according to claim 1, characterized in that the granulation layer ( 18 ; 45 ) has a minimum thickness of less than 5 cm, preferably a minimum thickness of less than 3 cm. Method according to claim 1 or 2, characterized in that the granulation layer ( 18 ; 45 ) via the transfer opening ( 6 ) to one within the treatment room ( 2 ) arranged second slide ( 4 ; 44 ), which are opposite to the first chute ( 3 ; 43 ) within the treatment room ( 2 ). Method according to claim 3, characterized in that the grain inlet ( 7 ) in an upper opening plane (P1) and the transfer opening ( 6 ) lie in a lower opening plane (P2), and that the connecting line between grain inlet (P2) 7 ) and transfer opening ( 6 ) includes with the horizontal a plant angle (γ) which is at least as large as a specific angle of repose (β) of the grain ( 11 ). Method according to one of the preceding claims, characterized in that the first chute ( 43 ; 43 ) has a sliding surface which includes with the horizontal a cascade angle (α) which is at least as large as a specific angle of repose (β) of the grain ( 11 ). Method according to claim 4 or 5, characterized in that the installation angle (γ) or the cascade angle (α) is greater than the specific angle of repose (β) of the grain size by a maximum of 10 °, preferably a maximum of 5 °. 11 ). Method according to one of the preceding claims, characterized in that the treatment gas the treatment room ( 2 ) from bottom to top and through the transfer opening ( 6 ) flows through. Method according to one of the preceding claims, characterized in that the treatment gas is a chlorine-containing reaction gas and that the grain ( 11 ) in the treatment room ( 2 ) experiences a residence time of at least 30 minutes. Treatment module for the treatment of free-flowing granulation ( 11 ) of inorganic raw material, with a heatable treatment room ( 2 ), which in an upper area has a grit inlet ( 7 ) and in a lower area a Körnungsauslass ( 8th ) and a gas inlet ( 9 ) and a gas outlet ( 10 ) for a treatment gas, characterized in that in the treatment room ( 2 ) a first slide ( 3 ; 43 ) at least over a part of the route between the granulation inlet ( 7 ) and graining outlet ( 8th ) located at a transfer opening ( 6 ) above the grain outlet ( 8th ) ends. Treatment module according to claim 9, characterized in that below the transfer opening ( 6 ) a second slide ( 4 ; 44 ), which are opposite to the first chute ( 3 ; 43 ) within the treatment room ( 2 ). Treatment module according to claim 10, characterized in that the granulation inlet ( 7 ) in an upper opening plane (P1) and the transfer opening ( 6 ) lie in a lower opening plane (P2), and that the connecting line between grain inlet (P2) 7 ) and transfer opening ( 6 ) includes with the horizontal a plant angle (γ) which is at least as large as a specific angle of repose (β) of the grain ( 11 ). Treatment module according to one of claims 9 to 11, characterized in that the first chute ( 3 ; 43 ) has a sliding surface which includes with the horizontal a cascade angle (α) which is at least as large as a specific angle of repose (β) of the grain ( 11 ). Treatment module according to claim 11 or 12, characterized in that the installation angle (γ) or the cascade angle (α) by a maximum of 10 °, preferably a maximum of 5 °, greater than the specific angle of repose (β) of the grain ( 11 ). Treatment module according to one of claims 9 to 13, characterized in that the gas inlet ( 9 ) in a plane below the level of the transfer opening ( 6 ) is arranged. Treatment module according to one of claims 9 to 14, characterized in that the transfer opening ( 6 ) is formed with a maximum opening width of 20 mm. Treatment module according to one of claims 9 to 15, characterized in that the Treatment room ( 2 ) and the at least one slide ( 3 . 4 . 5 . 43 . 44 ) consist of quartz glass. Treatment module according to one of claims 9 to 16, characterized in that it has a bottom, which with a connection element ( 19 ) is provided for grit inlet of at least one treatment chamber.

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