CN115435597A - Preparation method of low-heat-conductivity multilayer composite magnesium aluminate spinel brick for rotary kiln - Google Patents

Abstract

The invention relates to the technical field of fireproof energy-saving materials, and discloses a preparation method of a low-heat-conduction multilayer composite magnesium aluminate spinel brick for a rotary kiln, which comprises a working layer, a heat insulation layer and a heat insulation layer, and is characterized in that: the working layer is connected with the heat insulation layer, a gap is formed in the heat insulation layer, and the heat insulation layer is located in the gap; the working layer is made of aggregate, powder, a bonding agent and an additive, the aggregate and the powder account for 100wt%, the aggregate accounts for 60-65wt%, and the powder accounts for 35-40wt%, and the low-heat-conductivity multilayer composite magnesia-alumina spinel brick for the rotary kiln has the advantages that: the product of the invention depends on the advantages of a multilayer composite structure, has excellent high-temperature service performance, has a thermal conductivity coefficient far lower than that of similar products, can greatly reduce the surface temperature of a cylinder body when being used in a transition zone of a cement kiln through tests, and is 50-80 ℃ lower than that of similar products in the market.

Description

Preparation method of low-heat-conductivity multilayer composite magnesia-alumina spinel brick for rotary kiln

Technical Field

The invention relates to the technical field of fireproof energy-saving materials, in particular to a preparation method of a low-heat-conduction multilayer composite magnesia-alumina spinel brick for a rotary kiln.

Background

The rotary kiln is one of the main equipments in the production process of cement, lime, etc. The cement kiln will be exemplified below. The transition zone of the rotary cement kiln is adjacent to the burning zone, the kiln coating is not as firm as the burning zone, the temperature changes frequently, the flame enters and exits when hanging, the kiln coating falls off when hanging, the kiln lining material is always in a state without the protection of the kiln coating and is directly exposed under high-temperature radiation and hot airflow scouring, so the transition zone of the rotary cement kiln is a section zone, particularly a lower transition zone, with the most rigorous use condition of refractory materials in the rotary cement kiln. In the lower transition zone, granular clinker is strongly washed away, because the fluctuation range of the temperature bottom is far beyond other sections, the fiery plastic balls exchange heat with cold air (about 1100-1200 ℃) from the grate cooler, the heat exchange temperature difference is about 400-500 ℃, the clinker balls and the kiln skin exchange heat with secondary air of the grate cooler, and the thermal stress is very large. The clinker balls with 25-30% of liquid phase quantity are hardened and adhered to each other to form the kiln skin, and the kiln skin is extremely unstable under the action of the clinker balls and the kiln skin falling off from a burning zone, so that the workload is the worst. Therefore, the refractory material in the interval not only has high refractoriness, high refractoriness under load and high strength of the fired belt refractory material, but also has good thermal shock resistance and kiln coating hanging performance, so that the section of the kiln lining material not only bears chemical erosion caused by clinker, alkali compounds and the like, and thermal shock stripping of the material, erosive wear of the material and mechanical stress of mechanical vibration caused by thermal stress caused by temperature change.

The magnesia-chrome brick is commonly used in the transition zone before, but part of chrome in the magnesia-chrome brick can be changed from' Cr ³⁺ Conversion to virulent carcinogenic Cr ⁶⁺ ", is gradually eliminated by the rotary kiln. At present, the mainstream material used in the transition zone of the foreign rotary kiln is basically magnesia-alumina spinel bricks. Although the performance of the materials is very suitable for the service condition of the transition zone, the thermal conductivity of the magnesia-chrome brick is very high, and the thermal conductivity of the magnesia-alumina spinel brick reaches 4.3 w/m.k at 500 ℃, which is a very important factor for restricting the application of the magnesia-alumina spinel brick. The transition zone is not protected by a stable kiln crust unlike a firing zone, the temperature of the barrel is too high, so that the barrel is easy to deform to cause potential safety hazards, and meanwhile, the excessive heat loss also causes great energy waste, so that the invention provides the preparation method of the low-heat-conduction multilayer composite magnesia-alumina spinel brick for the rotary kiln.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides a preparation method of a low-heat-conduction multilayer composite magnesia-alumina spinel brick for a rotary kiln, which solves the problems in the background art.

(II) technical scheme

In order to realize the purpose, the invention provides the following technical scheme: the preparation method of the low-heat-conduction multilayer composite magnesium aluminate spinel brick for the rotary kiln comprises a working layer, a heat insulation layer and a heat insulation layer, wherein the working layer is connected with the heat insulation layer, a notch is formed in the heat insulation layer, and the heat insulation layer is positioned in the notch; the working layer is made of aggregate, powder, a bonding agent and an additive, the sum of the aggregate and the powder is 100wt%, the aggregate accounts for 60-65wt%, and the powder accounts for 35-40wt%; the composite binder accounts for 6-8wt% of the aggregate and the powder. The aggregate: 5-10wt% of fused magnesia particles with the granularity of 0-1mm, 10-15wt% of fused magnesia-alumina spinel particles with the granularity of 0-1mm, 25-30wt% of fused magnesia particles with the granularity of 1-3mm, 15-20wt% of fused magnesia particles with the granularity of 3-5mm, and the powder material comprises the following components in percentage by weight: 5-10wt% of fused magnesia-alumina spinel fine powder with the granularity less than 0.074mm, 15-20wt% of fused magnesia-alumina spinel fine powder with the granularity less than 0.074mm, 1-2wt% of metal aluminum powder with the granularity less than 0.045mm, 5wt% of defect spinel fine powder with the granularity less than 0.003mm and 1-2wt% of yttrium oxide fine powder with the granularity less than 0.045 mm.

Preferably, the composite binder is urea-formaldehyde resin and sulfurous acid pulp, and the binder is prepared from the following components in percentage by weight: the mass ratio of the sulfurous acid pulp waste liquid is 3.

Preferably, the main chemical component of the fused magnesia particles is MgO, and the content of MgO is 97 to 97.5 weight percent; the magnesium aluminate spinel particles mainly comprise the following chemical components: the MgO content is 32 to 33 weight percent, the Al2O3 content is 64 to 65 weight percent; the content of Al2O3 in the defect spinel fine powder is more than 90wt%.

Preferably, the heat-insulating layer is composed of aggregate, mixed fine powder and a high-temperature reinforcing agent, wherein the sum of the aggregate, the mixed fine powder and the high-temperature reinforcing agent is 100wt%, the aggregate is 55-60wt%, the mixed fine powder is 37-40wt%, the high-temperature reinforcing agent is 3-5wt%, the pore-forming agent is 1-2wt%, and the bonding agent is 3-5wt% of the sum of the aggregate, the mixed fine powder and the high-temperature reinforcing agent. The aggregate is as follows: 15-20wt% of porous magnesite grains with the granularity of 0-1mm, 25-30wt% of olivine grains with the granularity of 1-3mm and 15-20wt% of olivine grains with the granularity of 3-5 mm. The fine powder is: 30-35wt% of olivine fine powder with the granularity less than 0.074mm and 10-15wt% of porous magnesite fine powder with the granularity less than 0.074 mm.

Preferably, the high-temperature reinforcing agent is a product disclosed in Chinese patent ZL201410488950.3, the pore-forming agent is polyethylene fibers with the thickness of 0.3mm and 0.5mm, the bonding agent is low-sodium silica sol, and the chemical components of the bonding agent comprise, by mass, na2O < 0.006% and SiO2 > 30%.

Preferably, the heat insulation layer is a nano aerogel plate, the thermal conductivity of the nano aerogel plate is less than 0.02W/(m.K) (800 ℃), the maximum use temperature is 1150-1250 ℃, and the section of the notch is preferably trapezoidal, rectangular or in other geometrical shapes.

Preferably, the preparation method of the composite magnesia-alumina spinel brick comprises the following steps:

step one, batching:

a working layer: and (3) putting the granules with the particle size of not less than 0.074mm into a mixing mill, adding the composite binder into the mixing mill, mixing and milling for 5 minutes, adding the rest powder, and mixing and milling for 10 minutes for later use. Heat insulation layer: and (3) putting the granules with the particle size not less than 0.074mm and the pore-forming agent into a mixing mill, adding the novel binding agent, mixing and milling for 5 minutes, then sequentially adding the rest powder, and mixing and milling for 10 minutes for later use.

And step two, after the batching is finished, the mould is partitioned into a mould with the length ratio of 1-3 by a partition plate: 1-2, respectively adding the mud materials of the working layer and the heat insulation layer into the two compartments, and forming by adopting a press machine after extracting the partition plates.

And step three, drying the green bricks naturally for 24 hours, and then drying for 24 hours at 110 ℃.

And fourthly, firing.

Taking out the formed green brick, drying for 24 hours at 110 ℃, putting the green brick into a kiln, preserving the heat for 4 to 8 hours at 1510 to 1530 ℃, cooling, and bonding the nanometer aerogel plate to the notch of the cooled product to obtain the product.

(III) advantageous effects

Compared with the prior art, the invention provides a preparation method of a low-heat-conduction multilayer composite magnesia-alumina spinel brick for a rotary kiln, which has the following beneficial effects:

the preparation method of the low-heat-conductivity multilayer composite magnesium aluminate spinel brick for the rotary kiln, disclosed by the invention, has the beneficial effects that: the product of the invention depends on the advantages of a multilayer composite structure, has excellent high-temperature service performance, has a thermal conductivity coefficient far lower than that of similar products, can greatly reduce the surface temperature of a cylinder body when being used in a transition zone of a cement kiln through tests, and is 50-80 ℃ lower than that of similar products in the market.

Drawings

FIG. 1 is a schematic structural diagram of a preparation method of a low-heat-conductivity multilayer composite magnesia-alumina spinel brick for a rotary kiln, which is provided by the invention;

fig. 2 is a structural cross-sectional view of the preparation method of the low-heat-conductivity multilayer composite magnesium aluminate spinel brick for the rotary kiln.

In the figure: 1. working layer 2, heat preservation layer 3, insulating layer.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1:

as shown in figures 1 and 2, the low-heat-conduction multilayer composite magnesia-alumina spinel brick for the rotary kiln comprises a working layer 1, a heat insulation layer 2 and a heat insulation layer 3, wherein the working layer 1 is connected with the heat insulation layer 2, a notch is formed in the heat insulation layer 2, and the heat insulation layer 3 is positioned in the notch. The working layer 1 is prepared from aggregate, powder and a composite binder according to the following weight ratio: 65wt% of aggregate, 5wt% of fused magnesia particles with the granularity of 0-1mm, 10wt% of fused magnesia-alumina spinel particles with the granularity of 0-1mm, 30wt% of fused magnesia particles with the granularity of 1-3mm and 20wt% of fused magnesia particles with the granularity of 3-5 mm; 35wt% of powder, 10wt% of fused magnesia-alumina spinel fine powder with the granularity less than 0.074mm, 17wt% of fused magnesia-alumina spinel fine powder with the granularity less than 0.074mm, 2wt% of metal aluminum powder with the granularity less than 0.045mm, 5wt% of defect spinel fine powder with the granularity less than 0.003mm and 1 wt% of yttrium oxide fine powder with the granularity less than 0.045 mm. The heat-insulating layer 2 is prepared from aggregate, mixed fine powder, a high-temperature reinforcing agent, a pore-forming agent and an additional novel bonding agent according to the following weight ratio: 60wt% of aggregate, 36wt% of mixed fine powder, 4wt% of high-temperature reinforcing agent, 1.5wt% of pore-forming agent and 3-5wt% of novel bonding agent. The aggregate is as follows: 20wt% of porous magnesite grains with the granularity of 0-1mm, 25wt% of olivine grains with the granularity of 1-3mm and 15wt% of olivine grains with the granularity of 3-5 mm. The fine powder is: 30wt% of olivine fine powder with the granularity of less than 0.074mm and 10wt% of porous magnesite fine powder with the granularity of less than 0.074 mm. The pore-forming agent is polyethylene fiber, and the length of each of the pore-forming agent is 0.3mm and 0.5mm, and the length of each pore-forming agent accounts for 50 percent. The heat insulation layer 3 is a nanometer aerogel plate.

The preparation method comprises the following steps:

step one, batching:

a working layer: and (3) putting the granules with the particle size of not less than 0.074mm into a mixing mill, adding the composite binder into the mixing mill, mixing and milling for 5 minutes, adding the rest powder, and mixing and milling for 10 minutes for later use. Heat insulation layer: and (3) putting the granules with the particle size not less than 0.074mm and the pore-forming agent into a mixing mill, adding the novel binding agent, mixing and milling for 5 minutes, then sequentially adding the rest powder, and mixing and milling for 10 minutes for later use.

And step two, after the batching is finished, the mould is partitioned into a mould with the length ratio of 1-3 by a partition plate: 1-2, respectively adding the mud materials of the working layer and the heat insulation layer into the two compartments, and forming by adopting a press machine after extracting the partition plates.

And thirdly, naturally drying the green brick for 24 hours, and then drying the green brick for 24 hours at 110 ℃.

And fourthly, firing.

Taking out the formed green brick, drying at 110 ℃ for 24 hours, putting into a kiln, keeping the temperature at 1510 ℃ for 5 hours, cooling, and bonding the nano aerogel plate to the notch of the cooled product to obtain the product.

The implementation effect is as follows:

example 1 after the product is used in a transition zone of a rotary cement kiln, the temperature of a cylinder is reduced by 83 ℃ compared with the traditional magnesia-alumina spinel brick.

Specific example 2:

as shown in figures 1 and 2, the low-heat-conduction multilayer composite magnesium aluminate spinel brick for the rotary kiln comprises a working layer 1, an insulating layer 2 and a heat-insulating layer 3, wherein the working layer 1 is connected with the insulating layer 2, a gap is formed in the insulating layer 2, and the heat-insulating layer 3 is positioned in the gap. The working layer 1 is prepared from aggregate, powder and a composite binder according to the following weight ratio: 65wt% of aggregate, 5wt% of fused magnesia particles with the granularity of 0-1mm, 10wt% of fused magnesia-alumina spinel particles with the granularity of 0-1mm, 30wt% of fused magnesia particles with the granularity of 1-3mm and 20wt% of fused magnesia particles with the granularity of 3-5 mm; 35wt% of powder, 10wt% of fused magnesia-alumina spinel fine powder with the granularity less than 0.074mm, 17wt% of fused magnesia powder with the granularity less than 0.074mm, 2wt% of metal aluminum powder with the granularity less than 0.045mm, 5wt% of defect spinel fine powder with the granularity less than 0.003mm and 1.5wt% of yttrium oxide fine powder with the granularity less than 0.045 mm. The heat-insulating layer 2 is prepared from aggregate, mixed fine powder, a high-temperature reinforcing agent, a pore-forming agent and an additional novel bonding agent according to the following weight ratio: 60wt% of aggregate, 36wt% of mixed fine powder, 4wt% of high-temperature reinforcing agent, 2wt% of pore-forming agent, and 3-5wt% of novel bonding agent. The aggregate is as follows: 20wt% of porous magnesite grains with the granularity of 0-1mm, 25wt% of olivine grains with the granularity of 1-3mm and 15wt% of olivine grains with the granularity of 3-5 mm. The fine powder is: 30wt% of olivine fine powder with the granularity of less than 0.074mm and 10wt% of porous magnesia fine powder with the granularity of less than 0.074 mm. The pore-forming agent is polyethylene fiber, and the length of each of the pore-forming agent is 0.3mm and 0.5mm, and the length of each pore-forming agent accounts for 50 percent. The heat insulation layer 3 is a nanometer aerogel plate.

The preparation method comprises the following steps:

step one, batching:

a working layer: and (3) putting the granules with the particle size of not less than 0.074mm into a mixing mill, adding the composite binder into the mixing mill, mixing and milling for 5 minutes, adding the rest powder, and mixing and milling for 10 minutes for later use. Heat insulation layer: and (3) putting the granules with the particle size not less than 0.074mm and the pore-forming agent into a mixing mill, adding the novel binding agent, mixing and milling for 5 minutes, then sequentially adding the rest powder, and mixing and milling for 10 minutes for later use.

And secondly, after the material preparation, partitioning the die into a plurality of parts with the length ratio of 1-3: 1-2, respectively adding the mud materials of the working layer and the heat insulation layer into the two compartments, and forming by adopting a press machine after extracting the partition plates.

And step three, drying the green bricks naturally for 24 hours, and then drying for 24 hours at 110 ℃.

And fourthly, firing.

Taking out the formed green brick, drying at 110 ℃ for 24 hours, placing in a kiln, preserving heat at 1510 ℃ for 5 hours, cooling, and bonding the nanometer aerogel plate to the notch of the cooled product to obtain the product.

The implementation effect is as follows:

example 2 after the product is used in a transition zone of a rotary cement kiln, the temperature of a cylinder is reduced by 93 ℃ compared with the traditional magnesia-alumina spinel brick.

From the above embodiment 1 and embodiment 2, it can be seen that the heat conductivity coefficient of the product of the invention is far lower than that of the common magnesium aluminate spinel brick in the market, and the porous magnesia and olivine used can realize lower volume density, thereby reducing the self weight of the thermal equipment, effectively reducing the load when the motor of the equipment runs, the current when the motor runs and the power consumption per ton of the product due to the reduction of the self weight of the thermal equipment, simultaneously improving the running stability of the motor, reducing the maintenance times and providing guarantee for the long-term stable running of the equipment. The lower heat conductivity coefficient can also reduce heat loss, and the higher load soft temperature and thermal shock stability ensure the use safety and longer service life of the product. The magnesium aluminate spinel brick is used for replacing the prior common magnesium aluminate spinel brick, and has the advantages of prolonged service life and remarkable energy-saving and consumption-reducing effects.

In conclusion, the preparation method of the low-heat-conductivity multilayer composite magnesium aluminate spinel brick for the rotary kiln, disclosed by the invention, has the beneficial effects that: the product of the invention depends on the advantages of a multilayer composite structure, has excellent high-temperature service performance, has a thermal conductivity coefficient far lower than that of similar products, can greatly reduce the surface temperature of a cylinder body when being used in a transition zone of a cement kiln through tests, and is 50-80 ℃ lower than that of similar products in the market.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising one of 8230; \8230;" 8230; "does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (7)

1. The preparation method of the low-heat-conduction multilayer composite magnesium aluminate spinel brick for the rotary kiln comprises a working layer, a heat insulation layer and a heat insulation layer, and is characterized in that: the working layer is connected with the heat insulation layer, a gap is formed in the heat insulation layer, and the heat insulation layer is located in the gap; the working layer is made of aggregate, powder, a bonding agent and an additive, the sum of the aggregate and the powder is 100wt%, the aggregate accounts for 60-65wt%, and the powder accounts for 35-40wt%; the composite binder accounts for 6-8wt% of the aggregate and the powder. The aggregate is as follows: 5-10wt% of fused magnesia particles with the granularity of 0-1mm, 10-15wt% of fused magnesia-alumina spinel particles with the granularity of 0-1mm, 25-30wt% of fused magnesia particles with the granularity of 1-3mm, 15-20wt% of fused magnesia particles with the granularity of 3-5mm, and the powder material comprises the following components in percentage by weight: 5-10wt% of electric melting magnesia-alumina spinel fine powder with the granularity less than 0.074mm, 15-20wt% of electric melting magnesia powder with the granularity less than 0.074mm, 1-2wt% of metal aluminum powder with the granularity less than 0.045mm, 5wt% of defect spinel fine powder with the granularity less than 0.003mm and 1-2wt% of yttrium oxide fine powder with the granularity less than 0.045 mm.

2. The preparation method of the low-heat-conductivity multilayer composite magnesium aluminate spinel brick for the rotary kiln according to claim 1 is characterized in that: the composite binder is urea-formaldehyde resin and sulfurous acid paper pulp, and the binder is prepared from the following components in percentage by weight: the mass ratio of the sulfite pulp waste liquid is 3.

3. The preparation method of the low-heat-conductivity multilayer composite magnesium aluminate spinel brick for the rotary kiln according to claim 1 is characterized in that: the main chemical component of the fused magnesia particles is MgO, and the content of the MgO is 97 to 97.5 weight percent; the magnesium aluminate spinel particles mainly comprise the following chemical components: the MgO content is 32 to 33 weight percent, the Al2O3 content is 64 to 65 weight percent; the content of Al2O3 in the defect spinel fine powder is more than 90wt%.

4. The preparation method of the low-heat-conductivity multilayer composite magnesium aluminate spinel brick for the rotary kiln according to claim 1 is characterized in that: the heat-insulating layer is composed of aggregate, mixed fine powder and high-temperature reinforcing agent, wherein the sum of the aggregate, the mixed fine powder and the high-temperature reinforcing agent is 100wt%, the aggregate accounts for 55-60wt%, the mixed fine powder accounts for 37-40wt%, the high-temperature reinforcing agent accounts for 3-5wt%, the pore-forming agent accounts for 1-2wt%, and the bonding agent accounts for 3-5wt% of the sum of the aggregate, the mixed fine powder and the high-temperature reinforcing agent. The aggregate is as follows: 15-20wt% of porous magnesite grains with the granularity of 0-1mm, 25-30wt% of olivine grains with the granularity of 1-3mm and 15-20wt% of olivine grains with the granularity of 3-5 mm. The fine powder is as follows: 30-35wt% of olivine fine powder with the granularity of less than 0.074mm, and 10-15wt% of porous magnesia fine powder with the granularity of less than 0.074 mm.

5. The preparation method of the low-heat-conductivity multilayer composite magnesium aluminate spinel brick for the rotary kiln according to claim 1 is characterized in that: the high-temperature reinforcing agent is a product disclosed by Chinese patent ZL201410488950.3, the pore-forming agent is polyethylene fibers with the thickness of 0.3mm and 0.5mm, the bonding agent is low-sodium silica sol, and the high-temperature reinforcing agent comprises the chemical components with the mass percentage of Na2O less than 0.006 percent and SiO2 more than 30 percent.

6. The preparation method of the low-heat-conductivity multilayer composite magnesium aluminate spinel brick for the rotary kiln according to claim 1 is characterized in that: the heat insulation layer is a nano aerogel plate, the heat conductivity coefficient of the nano aerogel plate is less than 0.02W/(m.K) (800 ℃), the highest use temperature is 1150-1250 ℃, and preferably, the section of the notch is trapezoidal, rectangular or in other geometrical shapes.

7. The preparation method of the low-heat-conductivity multilayer composite magnesium aluminate spinel brick for the rotary kiln according to claim 1 is characterized in that: the preparation method of the composite magnesium aluminate spinel brick comprises the following steps:

step one, batching:

a working layer: and (3) putting the granules with the particle size of not less than 0.074mm into a mixing mill, adding the composite binder into the mixing mill, mixing and milling for 5 minutes, adding the rest powder, and mixing and milling for 10 minutes for later use. Heat insulation layer: and (3) putting the granules with the particle size not less than 0.074mm and the pore-forming agent into a mixing mill, adding the novel binding agent, mixing and milling for 5 minutes, then sequentially adding the rest powder, and mixing and milling for 10 minutes for later use.

And step two, after the batching is finished, the mould is partitioned into a mould with the length ratio of 1-3 by a partition plate: 1-2, respectively adding the mud materials of the working layer and the heat insulation layer into the two compartments, and forming by adopting a press machine after extracting the partition plates.

And step three, drying the green bricks naturally for 24 hours, and then drying for 24 hours at 110 ℃.

And fourthly, firing.

Taking out the formed green brick, drying for 24 hours at 110 ℃, putting the green brick into a kiln, preserving the heat for 4 to 8 hours at 1510 to 1530 ℃, cooling, and bonding the nanometer aerogel plate to the notch of the cooled product to obtain the product.

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