Preparation method of red mud-based high-sulfur tailings solid waste unfired brick

Abstract

The application discloses a preparation method of a red mud-based high-sulfur tailings solid waste unfired brick, and comprises the following steps: (1) mixing red mud, high-sulfur tailings powder and water, then heating, keeping warm and continuously stirring; after completion, performing solid-liquid separation, and washing, drying, grinding the obtained solid product to obtain a pretreated mixture; (2) mixing the alkaline liquid obtained through the solid-liquid separation and the washing liquid obtained through washing, then adding seaweed acid powder to neutralize; then performing solid-liquid separation, collecting the liquid phase to obtain mixing water; (3) taking the pretreated mixture, fly ash, aggregate, Portland cement and water reducing agent as raw materials, then adding the mixing water to form a slurry, and performing pressing and shaping after curing to obtain the unfired brick. The method utilizes the alkaline characteristics of the red mud to improve the volume stability of the high-sulfur tailings, alleviates the adverse effect of the high-sulfur tailings on the mechanical properties of the unfired brick, and realizes the resource utilization of the high-sulfur tailings and the red mud.

Description

Technical Field

[0001] This invention relates to the field of non-fired brick preparation technology, and in particular to a method for preparing non-fired bricks from red mud-based high-sulfur tailings solid waste. Background Technology

[0002] Bricks made by firing raw materials with fuel are called sintered bricks. Their disadvantages include high energy consumption and the generation of large amounts of greenhouse gases, sulfur dioxide, nitrogen oxides, and other toxic and harmful gases. Furthermore, the mining of clay required for brick production easily damages land resources. Non-fired bricks are a new type of building material made from non-clay raw materials, formed through pressing and curing. They do not require a high-temperature sintering process, thus effectively overcoming the aforementioned disadvantages of sintered bricks. High-sulfur tailings are a type of tailings. Compared to ordinary tailings, high-sulfur tailings contain a higher content of sulfur, such as tailings generated during the mining of lead-zinc and copper mines, which contain sulfides such as pyrite. When high-sulfur tailings are used as raw material to prepare non-fired bricks, the sulfides react with oxygen and mixing water to form sulfuric acid. This sulfuric acid reacts with calcium hydroxide, a cement hydration product in the non-fired bricks, to form calcium sulfate, which further transforms into expansive hydrated calcium sulfoaluminate (ettringite). Since the aforementioned processes mainly occur in the later stages of hydration in unfired bricks, the formation of ettringite easily creates internal stress within the bricks, leading to cracks and, in severe cases, even complete cracking and reduced mechanical properties. This characteristic of high-sulfur tailings prevents its direct use in unfired brick production like ordinary tailings, limiting its application. Exploring ways to overcome these problems is of significant practical importance for the resource utilization of this solid waste. Summary of the Invention

[0003] This invention discloses a method for preparing non-fired bricks from red mud-based high-sulfur tailings solid waste. This method utilizes the characteristics of red mud to improve the volume stability of high-sulfur tailings, mitigating its adverse effects on the mechanical properties of the non-fired bricks, while simultaneously realizing the resource utilization of large quantities of solid waste such as high-sulfur tailings and red mud. To achieve the above objectives, this invention discloses the following technical solutions.

[0004] A method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks includes the following steps:

[0005] (1) Mix red mud, high-sulfur tailings powder and water, then heat and keep warm while stirring continuously. After completion, perform solid-liquid separation, and wash, dry and grind the obtained solid product to obtain a pretreated mixture.

[0006] (2) The alkaline liquid obtained from the above solid-liquid separation is mixed with the washing liquid obtained from the washing process, and then alginate powder is added for neutralization. After completion, solid-liquid separation is performed, and the liquid phase is collected to obtain the mixed water.

[0007] (3) Using the pretreated mixture, fly ash, aggregate, silicate cement and water-reducing agent as raw materials, then adding the mixing water to form a slurry, pressing it into shape and curing it, thus obtaining non-fired bricks.

[0008] Further, in step (1), the ratio of red mud to high-sulfur tailings is 10 parts by weight: 4-6.5 parts by weight, and the material-to-liquid ratio of red mud to water is 1g: 10-15ml. Optionally, the fineness of the high-sulfur tailings is 200-300 mesh. Further, in step (1), the heating and heat preservation temperature is 50-70℃, and the time is 6-8h. The sulfuric acid formed by the reaction of sulfides in the high-sulfur tailings helps to promote the dissolution of alkaline components in the red mud and reduce the alkali content of the red mud itself.

[0009] Furthermore, in step (1), the ratio of water to solid product is 1g:20-35ml, and washing helps to further remove the residual red mud leachate from the solid product.

[0010] Furthermore, in step (1), the drying temperature is 110-130°C and the time is 1-2 hours.

[0011] Furthermore, in step (1), the fineness of the pretreated mixture obtained after grinding is not less than 150 mesh.

[0012] Furthermore, in step (2), the alginic acid is added to adjust the pH of the system to between 7 and 7.2.

[0013] Further, in step (3), the proportions of each component in the raw materials are as follows: 60-75 parts by weight of pretreated mixture, 25-32 parts by weight of fly ash, 40-48 parts by weight of fine aggregate, 30-35 parts by weight of silicate cement, and 0.15-0.27 parts by weight of water-reducing agent. The water-cement ratio of the mixing water to the cementitious material is 0.15-0.18, where the cementitious material refers to the pretreated mixture, fly ash, and silicate cement.

[0014] Further, in step (3), the fine aggregate includes any one of river sand, manufactured sand, coal gangue, etc. Optionally, the particle size of the fine aggregate is 1-3 mm.

[0015] Furthermore, in step (3), the water-reducing agent includes any one of polycarboxylate water-reducing agents, naphthalene-based water-reducing agents, lignin sulfonate water-reducing agents, etc.

[0016] Furthermore, in step (3), the raw materials also include at least one of barium slag and strontium slag. The barium and strontium elements provided by the barium and strontium slag help reduce the radioactivity in the red mud. Optionally, the amount of barium slag and / or strontium slag added is 15 to 18 parts by weight.

[0017] Furthermore, in step (3), the raw materials also include any one of polyethylene fiber, polypropylene fiber, or polyacrylonitrile fiber, which helps to further improve the mechanical properties of the non-fired bricks. Optionally, the amount of fiber added is 3 to 5 parts by weight. Optionally, the length of the fiber is 10 to 20 mm.

[0018] Furthermore, in step (3), the molding pressure is 8-12 MPa and the holding time is 20-30 s.

[0019] Furthermore, in step (3), the maintenance method is natural maintenance, which lasts for 14 to 28 days, and water is sprayed once every 18 to 24 hours during the maintenance period.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This invention involves mixing red mud, high-sulfur tailings, and water to form a mixture, which is then stirred under heating conditions. This process causes the soluble Na and K alkaline substances in the red mud to dissolve, while simultaneously reacting the sulfides in the high-sulfur tailings. The resulting sulfuric acid is neutralized by the alkaline substances provided by the red mud. On one hand, this effectively eliminates the problem of insufficient volume stability in high-sulfur tailings, which can easily lead to a decrease in the strength of unfired bricks. On the other hand, the alkaline leachate formed from the red mud in this process activates the high-sulfur tailings, causing the silicon-oxygen tetrahedra and aluminum-oxygen tetrahedra in the tailings to depolymerize and form active [SiO4]. 4- [AlO4] 5- The alginic acid reacts with Ca(OH)₂, a cement hydration product in the unfired bricks, to form hydrated calcium silicate and hydrated calcium aluminate, thereby enhancing the mechanical strength of the unfired bricks and helping to compensate for the insufficient strength of red mud-based unfired bricks. Furthermore, this invention converts the alkaline wastewater generated during the preparation of the pretreated mixture into mixing water for the unfired bricks, avoiding the generation of alkaline wastewater and overcoming the problem of efflorescence on the unfired bricks when using the wastewater. When alginic acid powder is added to the wastewater, it utilizes the alkaline environment provided by the wastewater to dissolve and undergo an acid-base neutralization reaction. This eliminates the alkalinity of the wastewater and converts the alginic acid into alginate. Simultaneously, the red mud, under the action of sulfuric acid generated from the high-sulfur tailings, can dissolve some aluminum, iron, calcium, and other elements. The polyvalent metal ions formed by these elements can cross-link the alginate to form a gel-like solid. This invention uses this method to solidify and remove the main alkaline elements Na and K from the wastewater. This allows the waste liquid to be used as mixing water in the preparation of non-fired bricks, achieving resource utilization, reducing waste liquid generation, and avoiding the problem of efflorescence on non-fired bricks. Attached Figure Description

[0022] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention and do not constitute an undue limitation of the invention. The embodiments of the invention are described in detail below with reference to the accompanying drawings, wherein:

[0023] Figure 1 The image shows a sample of the non-fired bricks prepared in Example 1 below. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0025] In the following embodiments, the main components of the red mud and high-sulfur tailings are shown in Tables 1 and 2 below.

[0026] Table 1 (Unit: wt.%)

[0027] Element <![CDATA[SiO2]]> <![CDATA[Al2O3]]> S Fe CaO MgO <![CDATA[MnO2]]> LOI Red mud 57.27 8.04 7.68 7.16 6.81 1.36 0.53 10.39

[0028] Table 2 (Unit: wt.%)

[0029] Element <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO <![CDATA[Fe2O3]]> <![CDATA[TiO2]]> <![CDATA[Na2O]]> <![CDATA[K2O]]> MgO LOI High sulfur tailings 20.34 19.86 5.92 28.73 2.16 10.44 0.04 1.25 9.38

[0030] Example 1

[0031] A method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks includes the following steps:

[0032] (1) Red mud powder and high-sulfur tailings powder with a fineness of 200 mesh were added to clean water at a ratio of 10 parts by weight: 5.5 parts by weight, with a material-to-liquid ratio of 1g:15ml. The resulting slurry was then heated to 60℃ and kept at that temperature for 7.5 hours, with continuous stirring during the heating process. After the process was completed, the system was cooled to room temperature and then filtered, and the solid product and filtrate were collected separately. The solid product was mixed with clean water at a ratio of 1g:30ml and washed, then filtered. The resulting solid product was dried at 115℃ for 1.5 hours and then ground. After the process was completed, the mixture was passed through a 200-mesh sieve to obtain the pretreated mixture.

[0033] (2) Mix the filtrate with the washing liquid obtained after washing and filtration, and then add alginate powder to adjust the pH of the system to 7.2. After standing for 10 minutes, filter to remove solids, collect the filtrate, and obtain the mixed water.

[0034] (3) Weigh the raw materials according to the following proportions: 70 parts by weight of the pretreated mixture in this embodiment, 28 parts by weight of fly ash, 45 parts by weight of fine aggregate, 33 parts by weight of 42.5 ordinary Portland cement, and 0.2 parts by weight of water-reducing agent. Wherein: the fly ash is Grade II fly ash, and the fine aggregate is river sand with a continuous gradation of 1-3 mm particle size. The water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of 25%.

[0035] (4) Mix the above raw materials evenly, then add the mixing water described in this embodiment at a water-cement ratio of 0.17. After stirring evenly, pour the resulting slurry into a mold, and then press it into shape under a pressure of 8 MPa for 30 seconds. Allow the resulting brick blank to cure naturally for 28 days, and spray water every 24 hours during the curing period, just enough to wet the surface of the brick blank. After completion, the unfired brick is obtained (e.g., Figure 1 (As shown).

[0036] The compressive strength and efflorescence degree of the unfired bricks prepared in this embodiment were tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012). The efflorescence degree is classified as follows: No efflorescence: Salt precipitation on the sample surface is almost invisible. Slight efflorescence: A fine and obvious efflorescence film appears on the sample surface, but the experimental surface is still clear. Moderate efflorescence: Obvious efflorescence layer appears on some surfaces or edges of the sample. Severe efflorescence: Brick powder, chipping, and peeling occur on the sample surface. The tested compressive strength was 33.61 MPa, and the efflorescence degree was no efflorescence.

[0037] Example 2

[0038] A method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks includes the following steps:

[0039] (1) Red mud powder and high-sulfur tailings powder with a fineness of 300 mesh were added to clean water at a ratio of 10 parts by weight: 6.5 parts by weight, with a material-to-liquid ratio of 1g:10ml. The resulting slurry was then heated to 50℃ and kept at that temperature for 8 hours, with continuous stirring during the heating process. After the process was completed, the system was cooled to room temperature and then filtered, and the solid product and filtrate were collected separately. The solid product was mixed with clean water at a ratio of 1g:35ml and washed, then filtered. The resulting solid product was dried at 130℃ for 1 hour and then ground. After the process was completed, it was passed through a 150-mesh sieve to obtain the pretreated mixture.

[0040] (2) Mix the filtrate with the washing liquid obtained after washing and filtration, and then add alginate powder to adjust the pH of the system to 7.0. After standing for 15 minutes, filter to remove solids, collect the filtrate, and obtain the mixed water.

[0041] (3) Weigh the raw materials according to the following proportions: 75 parts by weight of the pretreated mixture in this embodiment, 32 parts by weight of fly ash, 48 parts by weight of fine aggregate, 35 parts by weight of 42.5 ordinary Portland cement, and 0.27 parts by weight of water-reducing agent. Wherein: the fly ash is Grade II fly ash, and the fine aggregate is continuously graded coal gangue with a particle size of 1-3 mm. The water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of 28%.

[0042] (4) Mix the above raw materials evenly, then add the mixing water described in this embodiment at a water-cement ratio of 0.18. After stirring evenly, pour the resulting slurry into a mold, and then press it into shape under a pressure of 10 MPa for 25 seconds. Allow the resulting brick blanks to cure naturally for 28 days, and spray water every 20 hours during the curing period, just enough to wet the surface of the brick blanks. After completion, non-fired bricks are obtained.

[0043] The compressive strength and efflorescence degree of the unfired bricks prepared in this embodiment were tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012). The compressive strength was measured to be 30.46 MPa, and the efflorescence degree was found to be zero.

[0044] Example 3

[0045] A method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks includes the following steps:

[0046] (1) Red mud powder and high-sulfur tailings powder with a fineness of 250 mesh were added to clean water at a ratio of 10 parts by weight: 4 parts by weight, with a material-to-liquid ratio of 1g:15ml. The resulting slurry was then heated to 70℃ and kept at that temperature for 6 hours, with continuous stirring during the heating process. After the process was completed, the system was cooled to room temperature and then filtered, and the solid product and filtrate were collected separately. The solid product was mixed with clean water at a ratio of 1g:25ml and washed, then filtered. The resulting solid product was dried at 120℃ for 1.5 hours and then ground. After the process was completed, the mixture was passed through a 150-mesh sieve to obtain the pretreated mixture.

[0047] (2) Mix the filtrate with the washing liquid obtained after washing and filtration, and then add alginate powder to adjust the pH of the system to 7.1. After standing for 10 minutes, filter to remove solids, collect the filtrate, and obtain the mixed water.

[0048] (3) Weigh the raw materials according to the following proportions: 60 parts by weight of the pretreated mixture in this embodiment, 25 parts by weight of fly ash, 40 parts by weight of fine aggregate, 30 parts by weight of 42.5 ordinary Portland cement, 0.15 parts by weight of water-reducing agent, 15 parts by weight of barium slag, and 3 parts by weight of polypropylene fiber. Wherein: the fly ash is Grade II fly ash, the fine aggregate is river sand with a continuous gradation of 1-3 mm particle size, the water-reducing agent is a naphthalene-based water-reducing agent with a water reduction rate of 25%, and the polypropylene fiber has a length of 20 mm.

[0049] (4) Mix the above raw materials evenly, then add the mixing water described in this embodiment at a water-cement ratio of 0.16. After stirring evenly, pour the resulting slurry into a mold, and then press it into shape under a pressure of 12 MPa for 20 seconds. Allow the resulting brick blanks to cure naturally for 28 days, and spray water every 18 hours during the curing period, just enough to wet the surface of the brick blanks. After completion, non-fired bricks are obtained.

[0050] The compressive strength and efflorescence degree of the unfired bricks prepared in this embodiment were tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012). The compressive strength was measured to be 37.27 MPa, and the efflorescence degree was found to be zero.

[0051] Example 4

[0052] A method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks includes the following steps:

[0053] (1) Red mud powder and high-sulfur tailings powder with a fineness of 200 mesh were added to clean water at a ratio of 10 parts by weight: 4.5 parts by weight, with a material-to-liquid ratio of 1g:12ml. The resulting slurry was then heated to 55℃ and kept at that temperature for 6.5 hours, with continuous stirring during the heating process. After the process was completed, the system was cooled to room temperature and then filtered, and the solid product and filtrate were collected separately. The solid product was mixed with clean water at a ratio of 1g:20ml and washed, then filtered. The resulting solid product was dried at 110℃ for 2 hours and then ground. After the process was completed, it was passed through a 250-mesh sieve to obtain the pretreated mixture.

[0054] (2) Mix the filtrate with the washing liquid obtained after washing and filtration, and then add alginate powder to adjust the pH of the system to 7.0. After standing for 10 minutes, filter to remove solids, collect the filtrate, and obtain the mixed water.

[0055] (3) Weigh the raw materials according to the following proportions: 64 parts by weight of the pretreated mixture in this embodiment, 27 parts by weight of fly ash, 42 parts by weight of fine aggregate, 31 parts by weight of 42.5 ordinary Portland cement, 0.22 parts by weight of water-reducing agent, 18 parts by weight of strontium slag, and 5 parts by weight of polyethylene fiber. Wherein: the fly ash is Grade II fly ash, the fine aggregate is river sand with a continuous gradation of 1-3 mm particle size, the water-reducing agent is polycarboxylate superplasticizer with a water reduction rate of 25%, and the polyethylene fiber has a length of 10 mm.

[0056] (4) Mix the above raw materials evenly, then add the mixing water described in this embodiment at a water-cement ratio of 0.17. After stirring evenly, pour the resulting slurry into a mold, and then press it into shape under a pressure of 10 MPa for 30 seconds. Allow the obtained brick blanks to cure naturally for 28 days, and spray water once every 24 hours during the curing period, just enough to wet the surface of the brick blanks. After completion, non-fired bricks are obtained.

[0057] The compressive strength and efflorescence degree of the unfired bricks prepared in this embodiment were tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012). The compressive strength was measured to be 38.11 MPa, and the efflorescence degree was found to be zero.

[0058] Example 5

[0059] A method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks includes the following steps:

[0060] (1) Mix red mud powder and high-sulfur tailings powder with a fineness of 200 mesh at a ratio of 10 parts by weight to 5.5 parts by weight and then grind them. After grinding, pass the mixture through a 200-mesh sieve to obtain the pretreated mixture.

[0061] (2) Weigh the raw materials according to the following proportions: 70 parts by weight of the pretreated mixture in this embodiment, 28 parts by weight of fly ash, 45 parts by weight of fine aggregate, 33 parts by weight of 42.5 ordinary Portland cement, and 0.2 parts by weight of water-reducing agent. Wherein: the fly ash is Grade II fly ash, and the fine aggregate is continuously graded river sand with a particle size of 1-3 mm. The water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of 25%.

[0062] (3) Mix the above raw materials evenly, then add the mixing water prepared according to the method in Example 1 above at a water-cement ratio of 0.17. After stirring evenly, pour the resulting slurry into a mold, and then press it into shape under a pressure of 8 MPa for 30 seconds. Allow the obtained brick blanks to cure naturally for 28 days, and spray water once every 24 hours during the curing period, just enough to wet the surface of the brick blanks. After completion, non-fired bricks are obtained.

[0063] The compressive strength and efflorescence degree of the unfired bricks prepared in this embodiment were tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012). The compressive strength was measured to be 16.04 MPa, and the efflorescence degree was severe.

[0064] Example 6

[0065] A method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks includes the following steps:

[0066] (1) Red mud powder and high-sulfur tailings powder with a fineness of 200 mesh were added to clean water at a ratio of 10 parts by weight: 4.5 parts by weight, with a material-to-liquid ratio of 1g:12ml. The resulting slurry was then heated to 55℃ and kept at that temperature for 6.5 hours, with continuous stirring during the heating process. After the process was completed, the system was cooled to room temperature and then filtered, and the solid product and filtrate were collected separately. The solid product was mixed with clean water at a ratio of 1g:20ml and washed, then filtered. The resulting solid product was dried at 110℃ for 2 hours and then ground. After the process was completed, it was passed through a 250-mesh sieve to obtain the pretreated mixture.

[0067] (2) Mix the filtrate with the washing liquid obtained after washing and filtration to obtain mixing water, which is used for later use.

[0068] (3) Weigh the raw materials according to the following proportions: 64 parts by weight of the pretreated mixture in this embodiment, 27 parts by weight of fly ash, 42 parts by weight of fine aggregate, 31 parts by weight of 42.5 ordinary Portland cement, 0.22 parts by weight of water-reducing agent, 18 parts by weight of strontium slag, and 5 parts by weight of polyethylene fiber. Wherein: the fly ash is Grade II fly ash, the fine aggregate is river sand with a continuous gradation of 1-3 mm particle size, the water-reducing agent is polycarboxylate superplasticizer with a water reduction rate of 25%, and the polyethylene fiber has a length of 10 mm.

[0069] (4) Mix the above raw materials evenly, then add the mixing water described in this embodiment at a water-cement ratio of 0.17. After stirring evenly, pour the resulting slurry into a mold, and then press it into shape under a pressure of 10 MPa for 30 seconds. Allow the obtained brick blanks to cure naturally for 28 days, and spray water once every 24 hours during the curing period, just enough to wet the surface of the brick blanks. After completion, non-fired bricks are obtained.

[0070] The compressive strength and efflorescence degree of the unfired bricks prepared in this embodiment were tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012). The compressive strength was measured to be 28.32 MPa, and the efflorescence degree was severe.

[0071] Example 7

[0072] A method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks includes the following steps:

[0073] (1) Red mud powder and high-sulfur tailings powder with a fineness of 300 mesh were added to clean water at a ratio of 10 parts by weight: 6.5 parts by weight, with a material-to-liquid ratio of 1g:10ml. The resulting slurry was then heated to 50℃ and kept at that temperature for 8 hours, with continuous stirring during the heating process. After the process was completed, the system was cooled to room temperature and then filtered, and the solid product and filtrate were collected separately. The solid product was mixed with clean water at a ratio of 1g:35ml and washed, then filtered. The resulting solid product was dried at 130℃ for 1 hour and then ground. After the process was completed, it was passed through a 150-mesh sieve to obtain the pretreated mixture.

[0074] (2) Mix the filtrate with the washing liquid obtained after washing and filtration, and then add 10% hydrochloric acid solution to adjust the pH of the system to 7.0. After standing for 15 minutes, filter to remove solids, collect the filtrate, and obtain the mixed water.

[0075] (3) Weigh the raw materials according to the following proportions: 75 parts by weight of the pretreated mixture in this embodiment, 32 parts by weight of fly ash, 48 parts by weight of fine aggregate, 35 parts by weight of 42.5 ordinary Portland cement, and 0.27 parts by weight of water-reducing agent. Wherein: the fly ash is Grade II fly ash, and the fine aggregate is continuously graded coal gangue with a particle size of 1-3 mm. The water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of 28%.

[0076] (4) Mix the above raw materials evenly, then add the mixing water described in this embodiment at a water-cement ratio of 0.18. After stirring evenly, pour the resulting slurry into a mold, and then press it into shape under a pressure of 10 MPa for 25 seconds. Allow the resulting brick blanks to cure naturally for 28 days, and spray water every 20 hours during the curing period, just enough to wet the surface of the brick blanks. After completion, non-fired bricks are obtained.

[0077] The compressive strength and efflorescence degree of the unfired bricks prepared in this embodiment were tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012). The compressive strength was measured to be 31.15 MPa, and the efflorescence degree was severe.

[0078] Example 8

[0079] A method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks includes the following steps:

[0080] (1) Red mud powder and high-sulfur tailings powder with a fineness of 200 mesh were added to clean water at a ratio of 10 parts by weight: 5.5 parts by weight, with a material-to-liquid ratio of 1g:15ml. After stirring and mixing evenly, the resulting slurry was filtered, and the solid product and filtrate were collected separately. The solid product was mixed with clean water at a ratio of 1g:30ml, washed, and then filtered. The resulting solid product was dried at 115℃ for 1.5 hours and then ground. After completion, it was passed through a 200-mesh sieve to obtain the pretreated mixture.

[0081] (2) Mix the filtrate with the washing liquid obtained after washing and filtration, and then add alginate powder to adjust the pH of the system to 7.2. After standing for 10 minutes, filter to remove solids, collect the filtrate, and obtain the mixed water.

[0082] (3) Weigh the raw materials according to the following proportions: 70 parts by weight of the pretreated mixture in this embodiment, 28 parts by weight of fly ash, 45 parts by weight of fine aggregate, 33 parts by weight of 42.5 ordinary Portland cement, and 0.2 parts by weight of water-reducing agent. Wherein: the fly ash is Grade II fly ash, and the fine aggregate is river sand with a continuous gradation of 1-3 mm particle size. The water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of 25%.

[0083] (4) Mix the above raw materials evenly, then add the mixing water described in this embodiment at a water-cement ratio of 0.17. After stirring evenly, pour the resulting slurry into a mold, and then press it into shape under a pressure of 8 MPa for 30 seconds. Allow the obtained brick blanks to cure naturally for 28 days, and spray water once every 24 hours during the curing period, just enough to wet the surface of the brick blanks. After completion, non-fired bricks are obtained.

[0084] The compressive strength and efflorescence degree of the unfired bricks prepared in this embodiment were tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012). The compressive strength was measured to be 19.54 MPa, and the efflorescence degree was measured to be moderate.

[0085] Example 9

[0086] A method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks includes the following steps:

[0087] (1) Red mud powder and high-sulfur tailings powder with a fineness of 250 mesh were added to clean water at a ratio of 10 parts by weight: 4 parts by weight, with a material-to-liquid ratio of 1g:15ml. The resulting slurry was then heated to 70℃ and kept at that temperature for 6 hours, with continuous stirring during the heating process. After the process was completed, the system was cooled to room temperature and then filtered, and the solid product and filtrate were collected separately. The solid product was mixed with clean water at a ratio of 1g:25ml and washed, then filtered. The resulting solid product was dried at 120℃ for 1.5 hours and then ground. After the process was completed, the mixture was passed through a 150-mesh sieve to obtain the pretreated mixture.

[0088] (2) Mix the filtrate with the washing liquid obtained after washing and filtration, then add 10% hydrochloric acid solution to adjust the pH of the system to 7.1, and then add alginate powder to the system at a mass fraction of 0.1%. After stirring, let it stand for 10 minutes, then filter to remove solids, collect the filtrate, and obtain the mixed water.

[0089] (3) Weigh the raw materials according to the following proportions: 60 parts by weight of the pretreated mixture in this embodiment, 25 parts by weight of fly ash, 40 parts by weight of fine aggregate, 30 parts by weight of 42.5 ordinary Portland cement, 0.15 parts by weight of water-reducing agent, 15 parts by weight of barium slag, and 3 parts by weight of polypropylene fiber. Wherein: the fly ash is Grade II fly ash, the fine aggregate is river sand with a continuous gradation of 1-3 mm particle size, the water-reducing agent is a naphthalene-based water-reducing agent with a water reduction rate of 25%, and the polypropylene fiber has a length of 20 mm.

[0090] (4) Mix the above raw materials evenly, then add the mixing water described in this embodiment at a water-cement ratio of 0.16. After stirring evenly, pour the resulting slurry into a mold, and then press it into shape under a pressure of 12 MPa for 20 seconds. Allow the resulting brick blanks to cure naturally for 28 days, and spray water every 18 hours during the curing period, just enough to wet the surface of the brick blanks. After completion, non-fired bricks are obtained.

[0091] The compressive strength and efflorescence degree of the unfired bricks prepared in this embodiment were tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012). The compressive strength was measured to be 36.23 MPa, and the efflorescence degree was severe.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks, characterized in that, Including the following steps: (1) Mix red mud, high sulfur tailings powder and water, then heat and keep warm while stirring continuously; after completion, perform solid-liquid separation, and wash, dry and grind the obtained solid product to obtain pretreated mixture; the ratio of red mud to high sulfur tailings is 10 parts by weight: 4~6.5 parts by weight, and the ratio of red mud to water is 1g: 10~15ml. (2) The alkaline liquid obtained from the above solid-liquid separation is mixed with the washing liquid obtained from the washing process, and then alginate powder is added for neutralization; After completion, solid-liquid separation is performed, and the liquid phase is collected to obtain the stirred water; (3) Using the pretreated mixture, fly ash, aggregate, silicate cement, and water-reducing agent as raw materials, and then adding the mixing water to form a slurry, pressing it into shape and curing it, a non-fired brick is obtained; the proportion of each component in the raw materials is: 60-75 parts by weight of pretreated mixture, 25-32 parts by weight of fly ash, 40-48 parts by weight of aggregate, 30-35 parts by weight of silicate cement, and 0.15-0.27 parts by weight of water-reducing agent; the water-cement ratio of the mixing water to the cementitious material is 0.15-0.18, and the cementitious material refers to the pretreated mixture, fly ash, and silicate cement.

2. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to claim 1, characterized in that, The fineness of the high-sulfur tailings is 200-300 mesh.

3. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to claim 1, characterized in that, In step (1), the heating and heat preservation temperature is 50~70℃ and the time is 6~8h.

4. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to claim 1, characterized in that, In step (1), the ratio of water used for washing to solid product is 1g:20~35ml.

5. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to claim 1, characterized in that, In step (1), the drying temperature is 110~130℃ and the time is 1~2 hours.

6. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to claim 1, characterized in that, In step (1), the fineness of the pretreated mixture obtained after grinding is not less than 150 mesh.

7. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to claim 1, characterized in that, In step (2), the alginic acid is added to adjust the pH of the system to between 7 and 7.

2.

8. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to claim 1, characterized in that, In step (3), the aggregate includes any one of river sand, manufactured sand, and coal gangue.

9. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to claim 1, characterized in that, In step (3), the particle size of the aggregate is 1~3mm.

10. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to claim 1, characterized in that, In step (3), the water-reducing agent includes any one of polycarboxylate water-reducing agent, naphthalene-based water-reducing agent, and lignin sulfonate water-reducing agent.

11. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to any one of claims 1-10, characterized in that, In step (3), the raw materials also include at least one of barium slag and strontium slag.

12. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to claim 11, characterized in that, The amount of barium slag and / or strontium slag added is 15 to 18 parts by weight.

13. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to any one of claims 1-10, characterized in that, In step (3), the raw materials also include any one of polyethylene fiber, polypropylene fiber, and polyacrylonitrile fiber.

14. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to claim 13, characterized in that, The amount of fiber added is 3 to 5 parts by weight.

15. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to claim 13, characterized in that, The fiber has a length of 10~20mm.

16. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to any one of claims 1-10, characterized in that, In step (3), the molding pressure is 8~12MPa and the holding time is 20~30s.

17. The method for preparing red mud-based high-sulfur tailings solid waste non-fired bricks according to any one of claims 1-10, characterized in that, In step (3), the maintenance method is natural maintenance, which takes 14 to 28 days, and water is sprayed once every 18 to 24 hours during the maintenance period.

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