Process for preparing ceramic tiles, ceramic particles, or sintered products by wet direct modification of red mud slurry

Abstract

The present disclosure discloses a method for preparing ceramic tiles, ceramic particles, or sintered products by wet direct modification of red mud slurry, wherein the red mud slurry with a solid content of 10%-50% and a particle size within 0-2mm is discharged into a mixing tank as a raw material without pressure filtration, stacking, or other treatment methods, auxiliary materials are added to the mixing tank, and the red mud slurry is uniformly mixed and homogenized through stirring to modify the red mud slurry, with a ratio of the red mud slurry to the auxiliary materials of 1:1-9:1 by dry mass, and a percentage of silicon oxide and aluminum oxide by dry mass of the modified red mud slurry of 30-70%, then the red mud slurry after mixing and homogenization is subjected to pressure filtration; a solid waste filter cake is used as a raw material for sintered products, with a moisture content of 12-36%, to form ceramic wall, floor tiles, ceramic particles, or sintered products, then the ceramic wall, floor tiles, ceramic particles, or sintered products are made through molding, drying, and baking; the solid waste filter cake is also transported as the raw material for ceramic tiles, ceramic particles, or sintered products for subsequent processes; and a filtered liquid is recycled. 20 24 26 45 99 13 N ov 2 02 4 A B S T R A C T 2 0 2 4 2 6 4 5 9 9 1 3 N o v 2 0 2 4 T h e p r e s e n t d i s c l o s u r e d i s c l o s e s a m e t h o d f o r p r e p a r i n g c e r a m i c t i l e s , c e r a m i c p a r t i c l e s , o r s i n t e r e d p r o d u c t s b y w e t d i r e c t m o d i f i c a t i o n o f r e d m u d s l u r r y , w h e r e i n t h e r e d m u d s l u r r y w i t h a s o l i d c o n t e n t o f 1 0 % - 5 0 % a n d a p a r t i c l e s i z e w i t h i n 0 - 2 m m i s d i s c h a r g e d i n t o a m i x i n g t a n k a s a r a w m a t e r i a l w i t h o u t p r e s s u r e f i l t r a t i o n , s t a c k i n g , o r o t h e r t r e a t m e n t m e t h o d s , a u x i l i a r y m a t e r i a l s a r e a d d e d t o t h e m i x i n g t a n k , a n d t h e r e d m u d s l u r r y i s u n i f o r m l y m i x e d a n d h o m o g e n i z e d t h r o u g h s t i r r i n g t o m o d i f y t h e r e d m u d s l u r r y , w i t h a r a t i o o f t h e r e d m u d s l u r r y t o t h e a u x i l i a r y m a t e r i a l s o f 1 : 1 - 9 : 1 b y d r y m a s s , a n d a p e r c e n t a g e o f s i l i c o n o x i d e a n d a l u m i n u m o x i d e b y d r y m a s s o f t h e m o d i f i e d r e d m u d s l u r r y o f 3 0 - 7 0 % , t h e n t h e r e d m u d s l u r r y a f t e r m i x i n g a n d h o m o g e n i z a t i o n i s s u b j e c t e d t o p r e s s u r e f i l t r a t i o n ; a s o l i d w a s t e f i l t e r c a k e i s u s e d a s a r a w m a t e r i a l f o r s i n t e r e d p r o d u c t s , w i t h a m o i s t u r e c o n t e n t o f 1 2 - 3 6 % , t o f o r m c e r a m i c w a l l , f l o o r t i l e s , c e r a m i c p a r t i c l e s , o r s i n t e r e d p r o d u c t s , t h e n t h e c e r a m i c w a l l , f l o o r t i l e s , c e r a m i c p a r t i c l e s , o r s i n t e r e d p r o d u c t s a r e m a d e t h r o u g h m o l d i n g , d r y i n g , a n d b a k i n g ; t h e s o l i d w a s t e f i l t e r c a k e i s a l s o t r a n s p o r t e d a s t h e r a w m a t e r i a l f o r c e r a m i c t i l e s , c e r a m i c p a r t i c l e s , o r s i n t e r e d p r o d u c t s f o r s u b s e q u e n t p r o c e s s e s ; a n d a f i l t e r e d l i q u i d i s r e c y c l e d . A B S T R A C T 2 0 2 4 2 6 4 5 9 9 1 3 N o v 2 0 2 4 1 / 1 FIG. 1 FIG. 2 FIG. 3 1 / 1 the solid waste slurry with high solid waste filter water to solid filter pressing cake ratio filtrate recycling / discharging FIG. 1 water green bo drying / sintered dy / ball sintering auxiliary product material granulator stirring evenly molding solid waste filter cake FIG. 2 green body / drying / ball sintering the solid waste ceramics / mixing / ceramic slurry with filter high water to homoge nizing pressing particles / molding sintered sintered product solid ratio products auxiliary material filtrate recycling / discharging FIG. 3 20 24 26 45 99 13 N ov 2 02 4 1 / 1 t h e s o l i d w a s t e s l u r r y w i t h h i g h s o l i d w a s t e f i l t e r w a t e r t o s o l i d f i l t e r p r e s s i n g c a k e 2 0 2 4 2 6 4 5 9 9 1 3 N o v 2 0 2 4 r a t i o f i l t r a t e r e c y c l i n g / d i s c h a r g i n g F I G . 1 g r e e n b o d r y i n g / s i n t e r e d w a t e r d y / b a l l s i n t e r i n g p r o d u c t a u x i l i a r y m a t e r i a l g r a n u l a t o r s t i r r i n g e v e n l y m o l d i n g s o l i d w a s t e f i l t e r c a k e F I G . 2 g r e e n b o d y / d r y i n g / b a l l s i n t e r i n g t h e s o l i d w a s t e c e r a m i c s / m i x i n g / c e r a m i c s l u r r y w i t h f i l t e r h i g h w a t e r t o h o m o g e p a r t i c l e s / p r e s s i n g m o l d i n g s i n t e r e d n i z i n g s i n t e r e d p r o d u c t s o l i d r a t i o p r o d u c t s a u x i l i a r y m a t e r i a l f i l t r a t e r e c y c l i n g / d i s c h a r g i n g F I G . 3 c a k e 2 0 2 4 2 6 4 5 9 9 1 3 N o v 2 0 2 4 F I G . 2 c e r a m i c

Description

FIELD

[0001] The present disclosure relates to the field of the environmental protection, metallurgy, municipal engineering, mining, chemical engineering, and materials, specifically to a process for preparing ceramic tiles, ceramic particles, or sintered products by wet direct modification of red mud slurry. Background

[0002] In municipal, industrial and mining industries, the solid waste is discharged as slurry in many processes, such as the residual red mud, tailing mud, coal slurry, and tailings obtained after wet leaching and extraction of valuable elements in the smelting process, as well as municipal sludge, river sludge, and sludge formed in processes such as printing and dyeing, papermaking, material processing, and dust removal. The current method for utilizing these solid wastes is to first filter press these slurries in municipal, industrial, mining, or material processing industries to form tailings, and then transport them to sintering or ceramic production enterprises for resource utilization.

[0003] The red mud mainly comprises iron oxide, silicate, titanium oxide, incompletely-smelted aluminum containing minerals, and other metal oxides. Currently, the main scenarios with large-scale application potential are: raw materials produced by steelmaking, extraction of valuable elements, ecological restoration, and preparation of building materials. Generally speaking, the red mud with Fe2O3 content exceeding 30% can be considered a potential iron resource for the steel industry and can be used as a raw material for steel production. 2024264599   13 Nov 2024 However, due to the complex composition of impurities in the red mud, the impurities such as titanium dioxide, sodium oxide, aluminum oxide, and silicon dioxide in the red mud are not conducive to blast furnace ironmaking. Therefore, the total mixing amount of the red mud is low, usually not higher than 3%. Extracting the rare earth elements or other valuable elements from the red mud is relatively uneconomical, and its industrial production will meet certain challenges. Simultaneously, the red mud can only be reduced in quantity and cannot be fully quantified for consumption. As an ecological restoration material, although relevant optimizations can be made to address the shortcomings of strong alkalinity and low fertility level of the red mud, it is difficult to fundamentally achieve further development of substrate fertility. In addition, in order to prevent poor stability in vegetation reconstruction, it is necessary to consider the screening of resistant plants and the construction of plant communities through different plant configuration modes, which have long cycles and high costs. Simultaneously, the extensive research is still needed for practical application.

[0004] A large amount of Al2O3, SiO2, and some alkali metal oxides contained in red mud can be used as the main components for preparing ceramics, ceramic particles, or sintered products. Therefore, the red mud has potential in the preparation of ceramics or ceramic particles. Relevant scholars have further studied the solidification mechanism of the red mud ceramics on Na+ and found that plagioclase has a stronger solidification effect on Na+ compared to pyroxene. In ceramics with a mass fraction of 50% red mud, the dissolution rate of sodium and potassium ions is reduced by 91.6% compared to the unsintered red mud. Therefore, a large amount of the red mud can be used to prepare ceramic particles, sintered bricks, or ceramic tiles, achieving environmental and high-value utilization of the red mud. Besides, the 2024264599   13 Nov 2024 synergistic utilization of the red mud with coal gangue, coal slurry, sludge containing calorific value, as well as hazardous solid wastes such as anode mud and carbon slag emitted from the production process of electrolytic aluminum, can achieve the preparation of red mud ceramic particles and output steam or electricity at the same time. The process for extracting alumina from bauxite itself requires a large amount of steam, so the waste heat output from the kiln can be converted into steam, thereby achieving synergistic coupling with the material flow and energy flow of the alumina plant. It can be seen that the preparation of sintered materials such as ceramics or ceramic particles is an effective way to utilize red mud in an environmental, low-carbon, high-value, and bulk manner.

[0005] In addition, a large amount of sewage sludge with very high moisture content will be generated in urban domestic sewage treatment, which has become one of the major environmental problems that must be faced in the rapid development of urbanization. The existing disposal methods for sewage sludge, such as landfilling, composting, and incineration, are either not completely harmless or have high costs, making it difficult to dispose of the rapidly increasing discharge of sewage sludge. Based on the requirements of shale building materials for raw materials and the characteristics of the firing process, sewage sludge with a high moisture content is mixed with shale from a wide range of sources, and the water in sewage sludge is used as the necessary additional water in the production process of shale building material products. Simultaneously, the organic matter in the sewage sludge is used to supplement the heat value during the firing process of shale building material products, making it technically, economically, and environmentally friendly to directly use sewage sludge with a high moisture content for shale building material preparation. 2024264599   13 Nov 2024

[0006] However, there are several problems with the existing methods for preparing ceramic, ceramic or sintered raw materials: 1) The red mud slurry or raw materials with a high moisture content produced by alumina plants need to be dried in advance as raw materials due to their high moisture content, which will consume a lot of energy; 2) Even if extrusion molding technology is used, it is necessary to pre-filter and dehydrate these high moisture sludge raw materials or tail mud raw materials, and mix them with auxiliary materials. The existing mixing equipment has low efficiency in mixing and homogenizing wet materials, and also consumes a lot of energy; especially after pressure filtration, sludge or tailings are prone to compaction, and breaking them up will require additional energy consumption. Moreover, the dispersed particles are far less dispersed and have larger particle sizes than the suspended particles in the slurry, making it difficult to fully mix them with auxiliary materials; 3) During the wet material mixing process, as the moisture content of the auxiliary materials or mud fluctuates, it is not only necessary to test the moisture content, but also to add water to control its moisture content during the wet material mixing process, which increases the complexity of the process and wastes water resources.

[0007] summary

[0008] In order to deal with the shortcomings of existing technology, the present disclosure provides a process for preparing ceramic tiles, ceramic particles, or sintered products by wet direct modification of red mud slurry. The main purpose of this process is to: 1) Coupling processes between different industries, reducing 2024264599   13 Nov 2024 processes and energy consumption, and promoting the green and low-carbon transformation and upgrading of industries. Specifically, it refers to the process of directly using solid waste slurry with a high water to solid ratio from municipal, industrial, mining and other industries as raw materials for the subsequent preparation of sintered products. Compared with the existing method of first filtering and drying the solid waste slurry with a high water to solid ratio to form a filter cake with a certain moisture content, and then mixing the filter cake with other auxiliary materials and water to form sintered product raw materials, the auxiliary materials are directly mixed and homogenized with the solid waste slurry with a high water to solid ratio in this process, and then directly filtered to form raw materials of the sintered product; transforming the original solid waste discharging enterprises into production enterprises for sintered product raw materials allows building materials enterprises to directly utilize the filtered raw materials, reducing production costs. 2) Another purpose of this method is to better meet the requirements of solid waste utilization for thorough mixing of components and quality assurance. Sludge and tailings solid waste typically contain components such as alkali metals, heavy metals, and / or organic matter. Compared to traditional raw materials such as shale, clay, or slag, it is more necessary to thoroughly mix these solid wastes and auxiliary materials, so that they can fully react during the firing process, in order to solidify alkali metal and heavy metal ions, fully disperse and completely decompose and burn organic matter, and make the entire product composition react completely, effectively consolidating harmful 2024264599   13 Nov 2024 components such as alkali metal ions, free calcium oxide, or heavy metal ions, and achieving optimal overall performance. The solid waste particles in the slurry are small and suspended in the liquid, with the highest dispersion and particle size equal to their true particle size. After the auxiliary materials form a slurry, the wet-wet or solid-solid mixing process which is difficult is changed to simple liquid-liquid mixing or liquid-solid mixing, resulting in higher mixing efficiency, better quality of sintered raw materials after mixed slurry pressure filtration, and lower mixing energy consumption. 3) The advantage of this method is that solid waste slurry discharging enterprises can adjust their own processes to ensure the quality of the filter cake sold externally. The fluctuation of solid waste composition and moisture content is a major factor that makes it difficult to utilize. In solid waste discharging enterprises, the fluctuation of composition and moisture content of the solid waste slurry can be adjusted by changing the type of auxiliary materials or corresponding discharge process parameters according to the changes in the production process, so as to facilitate the control of the moisture and composition of the sintered product raw materials after pressure filtration. This makes it easier to coordinate the utilization of solid waste with the production source. The sintered product enterprises directly use raw materials with stable moisture and composition, and do not require further batching processes, which not only has low costs but also reduces the threshold for resource utilization enterprises. Therefore, the present disclosure is beneficial for controlling the quality of filter cake, improving process efficiency, reducing the utilization cost of sludge or tailings solid 2024264599   13 Nov 2024 waste in sintering product enterprises, and promoting the resource utilization of such solid waste. 4) The range of slurries that can be mixed is determined by the present disclosure. Not all slurries are suitable for direct modification and require appropriate components (the modified slurry should meet the sum of the percentages of silica and alumina of 40-80% by dry mass) and water to solid ratio (solid waste slurry with a high water to solid ratio having a solid content of 10% -50% and particle size mainly within 0-2mm), which can meet the processes of suspension, mixing, and subsequent sintering. Especially after pressure filtration, the moisture content can meet the requirements of 12-36% for ceramic particles or sintered products.

[0009] In order to achieve the above objectives, the present disclosure adopts the following technical solution:

[0010] A method for preparing ceramic tiles, ceramic particles, or sintered products by wet direct modification of red mud slurry, wherein the red mud slurry with a solid content of 10%-50% and a particle size within 02mm is discharged into a mixing tank as a raw material without pressure filtration, stacking, or other treatment methods, auxiliary materials are added to the mixing tank, and the red mud slurry is uniformly mixed and homogenized through stirring to modify the red mud slurry, with a ratio of the red mud slurry to the auxiliary materials of 1:1-9:1 by dry mass, and a percentage of silicon oxide and aluminum oxide by dry mass of the modified red mud slurry of 30-70%, then the red mud slurry after mixing and homogenization is subjected to pressure filtration; a solid waste filter cake is used as a raw material for sintered products, with a moisture content of 12-36%, to form ceramic wall, floor tiles, ceramic particles, or sintered products, then the ceramic wall, floor tiles, ceramic 2024264599   13 Nov 2024 particles, or sintered products are made through molding, drying, and baking; the solid waste filter cake is also transported as the raw material for ceramic tiles, ceramic particles, or sintered products for subsequent processes; and a filtered liquid is recycled.

[0011] In one embodiment, wherein the particle size of 98% of solid particles in the red mud slurry are within 0-2mm, and the solid particles is suspended in a liquid phase under stirring, with the solid content in different regions of the slurry changing within ± 5%, the red mud slurry includes the red mud slurry formed by extracting alumina in alumina industry, the red mud slurry with low iron left after iron selection from the red mud slurry formed by extracting alumina, or the red mud slurry formed by secondary slurry of a red mud.

[0012] In one embodiment, wherein the auxiliary materials include a mineral or solid waste powder, or a mixed powder of multiple minerals and / or solid waste, the minerals include shale, quartz, clay, and clay minerals, and the solid waste includes an industrial solid waste with high silicon aluminum component such as coal gangue, fly ash, gasification slag, tailings, and construction slag, and a maximum particle size of the powder is less than 2mm.

[0013] In one embodiment, wherein the auxiliary materials include another slurry excluding the red mud or a semi-solid viscous raw material obtained by pressure filtration of the red mud; the auxiliary materials include river silt, dredged sand, sludge generated and discharged during industrial production process of municipal sludge, slurry after wet beneficiation such as wet magnetic separation or flotation of solid waste, and tailings slurry after wet extraction of valuable elements from hazardous solid waste; slurry formed by manually wet grinding solid auxiliary materials, a maximum particle size of the solid particles is less than 2mm, which can be in the form of slurry or semi-solid viscous state, 2024264599   13 Nov 2024 with a solid content of 20%-80%.

[0014] In one embodiment, wherein, after adding the auxiliary materials to the red mud slurry in the mixing tank, the red mud slurry is homogenized by stirring to ensure a uniform composition of the mixed red mud slurry, a fluctuation rate of key indicators sampled from any two points in different areas of the homogenized red mud slurry is not greater than ± 10%; the key indicators include chemical compositions including silicon oxide, aluminum oxide, iron oxide, calcium oxide and magnesium oxide; content; solid content; calorific value; and ignition loss.

[0015] In one embodiment, the filtered liquid after pressure filtration is recycled, wherein for the red mud slurry directly produced and discharged in the alumina industry or the red mud slurry with a low iron after iron selection, auxiliary materials are directly added and homogenized before pressure filtration, and the filtered liquid is returned to the alumina plant for recycling; by utilizing the stored solid waste for secondary slurry, the slurry and auxiliary materials of the secondary slurry are mixed and homogenized, and then subjected to pressure filtration, the filtered liquid is returned to the secondary slurry for recycling.

[0016] In one embodiment, wherein a ceramic brick blank for preparing green bricks or balls include ordinary wall and floor tiles, ceramic floor stone brick blank, and the ceramic brick blank which is sintered includes standard bricks, porous bricks, or landscape bricks, with an average strength greater than 1.5 MPa; the particle size of extruded ceramic pellets is between 5-20mm, and the average compressive strength of a single ball is greater than 150N, the ball is directly applied in agriculture, forestry, and civil engineering without the need for subsequent high-temperature calcination processes.

[0017] In one embodiment, wherein traditional kilns include rotary kilns, tunnel 2024264599   13 Nov 2024 kilns, roller kilns, roasting kilns, sintering machines; the corresponding products include ceramic granules, sintered bricks, and ceramic tiles; the corresponding products include pellets produced by extrusion granulation, which is used as ceramic raw materials, refractory raw materials, cement mixtures or concrete admixtures, moisturizing ceramic particles, or ecological soil raw materials after high-temperature decarbonization roasting or activation.

[0018] In one embodiment, wherein the red mud slurry includes industrial or municipal sludge slurry.

[0019] DRAWINGS

[0020] FIG. 1 shows a traditional process for pre-treatment of the solid waste slurry, for example, the red mud slurry, with a high water to solid ratio;

[0021] FIG. 2 shows a process using solid waste filter cake to prepare ceramic tiles, ceramic particles or sintered products in the sintered products industry; and

[0022] FIG. 3 shows the process of the present disclosure, wherein the process shown in FIG. 1 and the process shown in FIG. 2 is coupled to create the new process of the present disclosure.

[0023] DETAILED DESCRIPTION

[0024] The present disclosure will be further described below. It should be noted that this embodiment is based on this technical solution and provides detailed implementation methods and specific operation processes. However, the scope of protection of the present disclosure is not limited to this embodiment.

[0025] Embodiment 1:

[0026] This embodiment provides a method for wet modification of sintered ceramic particles using red mud slurry directly produced and discharged from an alumina plant. The red mud slurry directly produced and discharged from the alumina plant is used as the main raw material, with 2024264599   13 Nov 2024 a solid content of 26% and a particle size of 90% less than 200 microns. Coal gangue powder is used as an auxiliary material, and the ratio of red mud to coal gangue is 3:2 by dry mass. After grinding the coal gangue, it is sieved through a 180 mesh (0.09mm) sieve, and the red mud slurry is discharged into a mixing tank. Then, the ground powder is added to the red mud slurry through a hopper, and the stirring blade in the red mud slurry is used for mixing and homogenization. In the modified slurry, the percentage of silica and alumina in a solid phase is 56% by dry mass. The solid suspension performance of the homogenized slurry is good, and the key indicators have been tested. The fluctuation of the composition in different regions of the homogenized slurry is less than ± 5%. After the slurry is filtered, the moisture content of the solid waste filter cake is 20%. Further, an extrusion granulator is used to extrude cylindrical particles with a diameter of 10mm and a length of 10-15mm. The average compressive strength of a single ball is greater than 150N. After shaping, the particles are sent to the roasting kiln for firing. The average compressive strength of the ceramic particles after firing is 16MPa, and the water absorption rate is 2.3%, which meets the requirements of the national standard for lightweight aggregates (GB / T17431.1-2010), and the cylinder compressive strength shall not be lower than 5.0MPa. Simultaneously, the filtered liquid meets the requirements for reuse in the alumina plant and can be returned to the alumina plant for recycling.

[0027] Embodiment 2

[0028] This embodiment provides a method for preparing sintered bricks directly by wet modification of red mud slurry. The main raw material is the red mud slurry directly produced and discharged from the alumina plant. The solid content of the red mud slurry is 33%, and 90% of the particle size is less than 150 microns. Coal gangue and slag powder are 2024264599   13 Nov 2024 mixed in a 1:1 ratio as the auxiliary material, and the ratio of the red mud to the auxiliary materials is 4:1 by mass. After crushing the coal gangue and slag, they are passed through a 2mm sieve, and the red mud slurry are discharged into the mixing tank. Then, the ground powder is added into the red mud slurry through a hopper, and mixed and homogenized through a mixing process. The sum of the percentages of silica and alumina in the modified slurry is 51% by dry mass. The solid suspension performance of the homogenized slurry is good, and the key indicators have been tested. The fluctuation of the composition in different regions of the homogenized slurry is less than ± 5%. After pressure filtration, the moisture content of the solid waste filter cake in the slurry is 22%. Further extrusion molding and cutting machines are used to form 290 x 190 x 90mm brick green bodies, with a flexural strength of 1.8-2.2MPa. The green bodies are then sent to tunnel drying kilns and tunnel firing kilns for firing. The average compressive strength of the brick green bodies after firing is 83MPa, and the finished product performance is qualified, meeting the requirements of the national standard for sintered pavement bricks (GB / T 26001-2010). The average flexural strength of SX type sintered pavement bricks is not less than 55MPa. Simultaneously, the filtered liquid meets the requirements for reuse in the alumina plant and can be returned to the alumina plant for recycling.

[0029] Embodiment 3

[0030] This embodiment provides a wet method for preparing sintered ceramic particles by directly modifying red mud slurry with a low iron after iron selection. The red mud slurry with a low iron after iron selection is used as the main raw material, and the solid content of the red mud slurry is 35%. The kiln slag slurry and fly ash powder after wet grinding and iron selection are used as auxiliary materials, and the ratio of desulfurization 2024264599   13 Nov 2024 tailings to auxiliary materials is 3:2 by dry mass. Simultaneously, kiln slag and fly ash with a particle size of less than 180 mesh are added to the red mud slurry, and the mixture is stirred and homogenized through a mixing process. The sum of the mass percentages of solid dry silica and alumina in the homogenized slurry is 48%, resulting in a homogenized slurry with a composition fluctuation of less than ± 7%. After the slurry is filtered, the moisture content of the solid waste filter cake is 18%. Further, an extrusion granulator is used to extrude cylindrical particles with a diameter of 12mm and a length of 10-16mm. The average compressive strength of a single ball is greater than 155N. After shaping, the particles are sent to a roasting kiln for firing. The average compressive strength of the fired ceramic particles is 13.52 MPa, and the water absorption rate is 3.3%, which meets the requirements of the national standard for lightweight aggregates (GB / T17431.1-2010), and the compressive strength of high-strength ceramic particles should not be lower than 6.5 MPa. The filtered liquid is returned to the alumina plant for recycling.

[0031] Embodiment 4

[0032] This embodiment provides a method for directly modifying and preparing ceramic particles by the stacked red mud which is pulpified again. The red mud slurry which is pulpified again is used as the main raw material, with a solid content of 40% and a particle size of less than 250 mesh. The construction waste soil is used as auxiliary material, and the ratio of red mud to auxiliary material is 7:3 by dry mass. The construction waste soil is pulpified again, with a solid content of 66% and a particle size of less than 2mm. The red mud slurry is mixed and homogenized with construction waste through mixing, and the percentage of the silica and alumina in the homogenized slurry is 62% by dry mass, obtaining a homogenized slurry with a composition 2024264599   13 Nov 2024 fluctuation of less than ± 6%. The moisture content of the solid waste filter cake after pressure filtration of the slurry is 12%. Further, an extrusion granulator is used to extrude cylindrical particles with a diameter of 15mm and a length of 10-15mm. The average compressive strength of a single ball is greater than 197N. After shaping, the particles are sent to a roasting kiln for firing. The average compressive strength of the fired ceramic particles is 11.64 MPa, and the water absorption rate is 6.3%, which meets the requirements of the national standard for lightweight aggregates (GB / T17431.1-2010). The compressive strength of high-strength ceramic particles in cylindrical form shall not be less than 6.5 MPa. The filtered liquid is returned to the secondary pulpified stage of the red mud for recycling.

[0033] Embodiment 5

[0034] This embodiment provides a wet direct modification process for preparing sintered bricks using the red mud slurry with a low iron produced by alumina plants after iron selection, with the selected red mud with a low iron as the main raw material and a solid content of 45%. The shale and tailings fine powder are used as auxiliary materials, with a particle size of less than 180 mesh. The ratio of red mud slurry to the auxiliary materials is 4:1 by dry mass. The auxiliary materials are added to the red mud slurry with a particle size less than 250 mesh, and mixed and homogenized through a stirring process. The homogenized slurry meets the requirement that the sum of the mass percentages of solid dry silica and alumina is 71%, obtaining a homogenized slurry with a component fluctuation of less than ± 10%. The remaining amount of the slurry after passing through an 80 mesh sieve does not exceed 1% by mass. The moisture content of the slurry after pressure filtration is 13%. It is further processed using an extrusion molding machine and a cutting machine to form a 290 x 190 x 90mm brick body with a flexural 2024264599   13 Nov 2024 strength of 1.8-2.2MPa. The brick body is then sent to a tunnel drying kiln and a tunnel firing kiln for firing. The average compressive strength of the brick body after firing is 66MPa. The performance of the sintered brick product is qualified and meets the requirements of the national standard for sintered pavement bricks (GB / T 26001-2010). The average flexural strength of SX type sintered pavement bricks is not less than 55MPa. The filtered liquid meets the requirements for returning to the alumina plant, so the filtered liquid is returned to the alumina plant for recycling.

[0035] Embodiment 6

[0036] This embodiment provides a method for directly modifying sintered bricks using a wet process of the stacked red mud which is pulpified again. The main raw material is the red mud slurry formed by the stacked red mud which is pulpified again. The solid content of the red mud slurry is 35%, and the mixture of fly ash and slag powder is used as auxiliary material. The ratio of red mud to auxiliary material is 6:4 by dry mass. After grinding coal gangue and slag, they are passed through a 2mm sieve, and the red mud slurry are discharged into the mixing tank. Then, the ground powder is added into the red mud slurry through a hopper, and mixed and homogenized through a mixing process. In the modified slurry, the percentage of silica and alumina in a solid phase is 52% by dry mass. The solid suspension performance of the homogenized slurry is good, and the key indicators have been tested. The fluctuation of the composition in different regions of the homogenized slurry is less than ± 5%. After pressure filtration, the moisture content of the solid waste filter cake in the slurry is 19%. Further extrusion molding and cutting machines are used to form 290 x 190 x 90mm brick green bodies with a flexural strength of 1.8-2.2MPa. The green bodies are then sent to tunnel drying kilns and tunnel firing 2024264599   13 Nov 2024 kilns for firing. The average compressive strength of the brick green bodies after firing is 85MPa, and the performance of the sintered brick products is qualified, meeting the requirements of the national standard for sintered pavement bricks (GB / T 26001-2010). The average flexural strength of SX type sintered pavement bricks is not less than 55MPa. Simultaneously, the filtered liquid is returned to the secondary slurry stage of the stored red mud for recycling.

[0037] Embodiment 7

[0038] This embodiment provides a method for directly modifying red mud slurry produced and discharged by an alumina plant to prepare ceramic tiles. The main raw material is directly produced and discharged red mud slurry, with a solid content of 46%. The mixture formed by mixing slag and shale in a 1:1 ratio is used as auxiliary material, and the ratio of red mud slurry to auxiliary material by dry mass is 1:1. The mixture of slag and shale is ground and passed through a 2mm sieve. The red mud slurry is discharged into a mixing tank, and then the ground auxiliary materials are added to the red mud slurry through a hopper, and stirred and homogenized through a stirring process. The modified slurry meets the requirement that the sum of the mass percentages of solid-phase dry silica and alumina is 46%. The solid suspension performance of the homogenized slurry is good, and the key indicators have been tested. The fluctuation of the composition in different regions of the homogenized slurry is less than ± 5%. After the slurry is filtered, the moisture content of the solid waste filter cake is 15%. Further, the corresponding preparation process of ceramic bricks is used to prepare 300 x 200 x 80mm ceramic brick green bodies with a flexural strength of 1.8-2.2MPa. After shaping, the ceramic tiles are sent to a roller kiln for firing. After firing, the compressive strength of the ceramic tiles is not less than 45MPa, and the water absorption rate is 0.06%. 2024264599   13 Nov 2024 Simultaneously, the filtered liquid meets the requirements for reuse in alumina plants and can be returned to alumina for recycling.

[0039] Embodiment 8

[0040] This embodiment provides a method for directly modifying and preparing ceramic tiles using red mud slurry with a low iron discharged after iron selection from the red mud slurry produced by an alumina plant. The red mud slurry with a low iron is used as the main raw material, with a solid content of 10%. Urban tailings and waste soil are mixed in a 1:1 ratio as auxiliary materials, and the mixture of urban tailings and waste soil is ground and sieved through a 2mm sieve. The ratio of red mud slurry to the auxiliary materials by dry mass is 3:2. The red mud slurry is discharged into the mixing pool, and the corresponding quality of urban tailings and slag mixture is added to the slurry through a hopper, and stirred and homogenized through a mixing process. In the modified slurry, the percentage of silica and alumina in a solid phase by dry mass is 48%. The solid suspension performance of the homogenized slurry is good, and the key indicators have been tested. The fluctuation of the composition in different regions of the homogenized slurry is less than ± 5%. After the slurry is filtered, the moisture content of the solid waste filter cake is 35%. Further, the corresponding preparation process of ceramic bricks is used to prepare 300 x 200 x 80mm ceramic brick green bodies with a flexural strength of 1.8-2.2MPa. After shaping, the ceramic tiles are sent to a roller kiln for firing. After firing, the compressive strength of the ceramic tiles is not less than 35MPa, and the water absorption rate is 0.7%. The filtered liquid can be returned to the red mud secondary slurry stage for recycling.

[0041] Embodiment 9

[0042] This embodiment provides a wet method for preparing sintered ceramic particles by directly modifying the red mud slurry after secondary slurry 2024264599   13 Nov 2024 storage. The red mud slurry is used as the main raw material, with a solid content of 40% and a particle size of 90% less than 1mm. The clay with a particle size less than 180 mesh is mixed with fly ash in a ratio of 1:3 by dry mass as auxiliary materials. The auxiliary materials are added to the red mud slurry and homogenized through a stirring process. The homogenized mixed slurry meets the requirement that the sum of the mass percentages of solid-phase dry silica and alumina is 52%, resulting in a homogenized slurry with a composition fluctuation of less than ± 7%. After the slurry is filtered, the moisture content of the solid waste filter cake is 18%. Further, an extrusion granulator is used to extrude cylindrical particles with a diameter of 12mm and a length of 10-15mm. The average compressive strength of a single ball is greater than 160N. After shaping, the particles are sent to the roasting kiln for firing. The average compressive strength of the fired ceramic particles is 12.65MPa, and the water absorption rate is 6.3%, which meets the requirements of the national standard for lightweight aggregates (GB / T17431.1-2010) that the cylindrical compressive strength of high-strength ceramic particles should not be less than 6.5MPa. The filtered liquid will be sent to the solid waste discharging enterprise for recycling.

[0043] For technicians in this field, various corresponding changes and modifications can be proposed based on the above technical solutions and concepts, and all of these changes and modifications should be included within the scope of protection of the present disclosure.

Claims

1. A method for preparing ceramic tiles, ceramic particles, or sintered products by wet direct modification of red mud slurry, wherein the red mud slurry with a solid content of 10%-50% and a particle size of 98% of solid particles within 0-2mm is discharged into a mixing tank as a raw material without pressure filtration, stacking, or other dewatering treatment methods, auxiliary materials are added to the mixing tank, and the red mud slurry is uniformly mixed and homogenized through stirring to modify the red mud slurry, with a ratio of the red mud slurry to the auxiliary materials of 1:19:1 by dry mass, and a percentage of silicon oxide and aluminum oxide by dry mass of the modified red mud slurry of 30-70%, then the red mud slurry after mixing and homogenization is subjected to pressure filtration to produce a solid waste filter cake; wherein the auxiliary materials comprise a mineral or solid waste powder, or a mixed powder of multiple minerals and / or solid waste, the minerals comprise shale, clay, and clay minerals, and the solid waste comprises coal gangue, fly ash, gasification slag, tailings, and construction slag, and a maximum particle size of the powder is less than 2mm;the solid waste filter cake is used as a raw material for sintered products, with a moisture content of 12-36%, to form ceramic wall, floor tiles, ceramic particles, or sintered products, then the ceramic wall, floor tiles, ceramic particles, or sintered products are made through molding, drying, and baking; the solid waste filter cake is also transported as the raw material for ceramic tiles, ceramic particles, or sintered products for subsequent processes; and a filtered liquid is recycled.

2. The method according to claim 1, wherein the particle size of 98% of solid particles in the red mud slurry are within 0-2mm, and the solid particles is suspended in a liquid phase under stirring, with the solid content in different regions of the slurry changing within ± 5%, the red mud slurry comprises the red mud slurry formed by extracting alumina in alumina industry, the red mud slurry with low iron left after iron selection from the red mud slurry formed by extracting alumina, or the red mud slurry formed by secondary slurry of a red mud.2024264599   29 Sep 20263. The method according to claim 1, wherein, after adding the auxiliary materials to the red mud slurry in the mixing tank, the red mud slurry is homogenized by stirring to ensure a uniform composition of the mixed red mud slurry, a fluctuation rate of key indicators sampled from any two points in different areas of the homogenized red mud slurry is not greater than ± 10%; the key indicators comprise chemical compositions including silicon oxide, aluminum oxide, iron oxide, calcium oxide and magnesium oxide; content; solid content; calorific value; and ignition loss.

4. The method according to claim 1, wherein the filtered liquid after pressure filtration is recycled, wherein for the red mud slurry directly produced and discharged in the alumina industry or the red mud slurry with a low iron after iron selection, auxiliary materials are directly added and homogenized before pressure filtration, and the filtered liquid is returned to the alumina plant for recycling; by utilizing the stored solid waste for secondary slurry, the slurry and auxiliary materials of the secondary slurry are mixed and homogenized, and then subjected to pressure filtration, the filtered liquid is returned to the secondary slurry for recycling.

5. The method according to claim 1, wherein a ceramic brick blank for preparing green bricks or balls comprises ordinary wall and floor tiles, ceramic floor stone brick blank, and the ceramic brick blank which is sintered comprises standard bricks, porous bricks, or landscape bricks, with an average strength greater than 1.5 MPa; the particle size of extruded ceramic pellets is between 5-20mm, and the average compressive strength of a single pellet is greater than 150N, the pellet is directly applied in agriculture, forestry, and civil engineering without the need for subsequent high-temperature calcination processes.

6. The method according to claim 1, wherein the baking takes place in traditional kilns, which comprise rotary kilns, tunnel kilns, roller kilns, roasting kilns, sintering machines;the ceramic or sintered products comprise ceramic granules, sintered bricks, ceramic tiles, and pellets produced by extrusion granulation, which is used as ceramic raw materials, refractory raw materials, cement mixtures or concrete admixtures, moisturizing ceramic particles, or ecological soil raw materials after high-temperature2024264599   29 Sep 2026decarbonization roasting or activation.

7. The method according to claim 1, wherein the red mud slurry comprises industrial or municipal sludge slurry.

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