A method for preparing porous ceramics using high-iron slag

Abstract

This invention discloses a method for preparing porous ceramics using high-iron slag. The method involves grinding high-iron slag powder, methacrylamide, N,N-methylenebisacrylamide, and water in a ball mill, then passing the mixture through a 150-mesh sieve to obtain a slurry. Ammonium persulfate and N,N,N,N-tetramethylethylenediamine are then added sequentially to water and stirred to obtain a mixture. This mixture is added to the slurry, stirred until homogeneous, and then poured into a mold. After the slurry in the mold solidifies, it is dried and demolded to obtain a green body. The green body is then dried and fired in a kiln at a maximum firing temperature of 1050–1250℃ for 1–3 hours. After firing, it is cooled to obtain porous ceramics. This invention not only enables the use of high-iron slag as a raw material for the production of porous ceramics, but also results in porous ceramics with good flexural strength and porosity.

Description

Technical Field

[0001] This invention belongs to the field of porous ceramic materials technology, specifically relating to a method for preparing porous ceramics using high-iron slag. Background Technology

[0002] Mineral slag, a byproduct of mineral mining and beneficiation, is a massive solid waste that can severely harm the environment if not properly managed. However, utilizing it as a raw material for certain bulk products can generate significant economic and social benefits. For instance, the chemical composition of mineral slag is similar to that of ceramic raw materials, making it possible to use it in the preparation of porous ceramics. Porous ceramics are a novel type of ceramic material with wide applications in gas or liquid filtration, purification and separation, chemical catalyst carriers, sound absorption and vibration damping, and many other areas, possessing considerable economic value.

[0003] However, in the preparation process of porous ceramics, the composition of the raw material has a significant impact on the pore size and porosity of the porous ceramics, which in turn affects the performance of the porous ceramic materials. Using low-quality and complex slag as raw material to prepare porous ceramics will reduce the flexural strength and porosity of the porous ceramics, which seriously hinders the application of slag in the production of porous ceramics. Summary of the Invention

[0004] To address the aforementioned shortcomings, this invention discloses a method for preparing porous ceramics using high-iron slag. This method not only enables the use of high-iron slag as a raw material in the production of porous ceramics, but also results in porous ceramics with good flexural strength and porosity.

[0005] This invention is achieved using the following technical solution:

[0006] A method for preparing porous ceramics using high-iron slag, comprising the following steps:

[0007] (1) Take high-iron slag powder, methacrylamide, N,N-methylenebisacrylamide and water, put them into a ball mill and grind them, and then pass them through a 150-mesh sieve to obtain a slurry. The weight ratio of the high-iron slag powder, methacrylamide, N,N-methylenebisacrylamide and water is 100:(2~6):(0.5~3):(30~45).

[0008] (2) Take ammonium persulfate and N,N,N,N-tetramethylethylenediamine and add them to water in sequence, then stir and mix to obtain a mixture. The weight ratio of ammonium persulfate, N,N,N,N-tetramethylethylenediamine and water is (5-20):(1-10):(10-100). The weight ratio of methacrylamide and ammonium persulfate in step (1) is 100:(5-20).

[0009] (3) Add the mixture obtained in step (2) to the slurry obtained in step (1), stir and mix evenly, then pour into the mold. After the slurry in the mold has solidified, dry and demold to obtain the green body; add the mixture containing ammonium persulfate and N,N,N,N-tetramethylethylenediamine to the slurry containing high-iron slag powder, methacrylamide, N,N-methylenebisacrylamide and water to react. Use ammonium persulfate and N,N,N,N-tetramethylethylenediamine to initiate the cross-linking reaction between high-iron slag powder, methacrylamide and N,N-methylenebisacrylamide, improve the curing effect of the slurry, and thus improve the strength of the ceramic green body;

[0010] (4) After drying the green body obtained in step (3), it is placed in a kiln for firing. The firing temperature is maintained at 1050-1250℃ for 1-3 hours. After firing, it is cooled to obtain porous ceramic.

[0011] Furthermore, the high-speed iron slag powder is obtained by crushing high-speed iron slag, and the particle size of the high-speed iron slag powder is not higher than 300 micrometers.

[0012] Furthermore, the high-iron slag powder comprises the following components by mass fraction: silicon dioxide 30-55%, aluminum oxide 8-18%, ferric oxide 10-22%, calcium oxide 10-20%, magnesium oxide 2-8%, and other oxides and loss on ignition totaling 5-13%. The other oxides include sulfur trioxide, potassium oxide, sodium oxide, manganese oxide, titanium oxide, zinc oxide, etc.

[0013] Furthermore, if the content of silicon dioxide, aluminum oxide, calcium oxide and ferric oxide in the high-speed iron slag powder does not meet the composition requirements of the high-speed iron slag powder, natural minerals are added, wherein the natural minerals are one or more combinations of quartz, clay, limestone and red mud.

[0014] Furthermore, in step (1), the high-iron slag powder and water are first put into a ball mill for grinding. When the particle size of the material in the ball mill reaches 20 to 200 micrometers, methacrylamide and N,N-methylenebisacrylamide are added in sequence for mixing and grinding. Then, the mixture is passed through a 150-mesh sieve to obtain a slurry.

[0015] Furthermore, a foaming agent is added to the slurry obtained in step (1) and stirred to form a large number of bubbles. Then, the mixture obtained in step (2) is poured into the slurry, stirred evenly, and then poured into a mold. After the slurry in the mold has solidified, it is dried and demolded to obtain the green body. Adding a foaming agent to the slurry first, and then adding the mixture for reaction and solidification, can ensure sufficient foaming and operation time, which is beneficial for forming a porous structure and actual production operation.

[0016] Furthermore, in step (3), the mixture obtained in step (2) is added to the slurry obtained in step (1) and stirred until uniform. Then, a foaming agent is added and stirred until uniform, so that a large number of bubbles are formed in the slurry. The mixture is then poured into a mold. After the slurry in the mold has solidified, it is dried and demolded to obtain a blank. The weight of the foaming agent is 0.5 to 8% of the weight of the high-iron slag powder in step (1). The mixture is added to the slurry first for reaction, and then the foaming agent is added for foaming treatment, and then solidification is carried out. This shortens the time before foaming and bubble solidification, making it less likely for the foam to break after formation, and avoiding the formation of porous structure due to reduced foam.

[0017] Furthermore, the foaming agent is one or more combinations of sodium dodecylbenzenesulfonate, hydrogen peroxide, animal protein, plant protein, and triethanolamine lauryl sulfate. This invention screens suitable foaming agents and selects appropriate addition times based on the characteristics of the foaming agent type, thereby facilitating better foaming effects and promoting the formation of porous structures.

[0018] Furthermore, the stirring speed in step (2) is 150–300 r / min; the stirring speed in step (3) is 200–400 r / min. In step (2), controlling the stirring speed of ammonium persulfate, N,N,N,N-tetramethylethylenediamine and water promotes the rapid dissolution and uniform mixing of ammonium persulfate and N,N,N,N-tetramethylethylenediamine in water; in step (3), since the properties of the mixture and slurry are different, adjusting the stirring speed can promote the rapid and uniform mixing of the two materials, and can also promote the interaction of the components in the materials, thereby improving the reaction efficiency.

[0019] Furthermore, in step (4), the green body is dried at 50-80°C, and the moisture content of the dried green body is less than 3%. The moisture content of the dried green body is strictly controlled to be below 3% to avoid cracking of the green body during subsequent firing.

[0020] Compared with existing technologies, this technical solution has the following advantages:

[0021] 1. The porous high-speed ferrous slag ceramic material prepared by this invention has interconnected micropores between the macroscopic large air bubbles, resulting in a high apparent porosity (through-pore ratio), which is one of the characteristics of the porous high-speed ferrous slag ceramic material prepared by this invention. The porous high-speed ferrous slag ceramic material prepared by this invention can be used in ceramic membrane products for filtration, noise reduction products for sound absorption and vibration damping, carrier products for chemical catalysis, and special wall materials for construction, etc.

[0022] 2. This invention utilizes high-iron ore slag as a raw material to produce porous ceramics that achieve exceptionally high flexural strength while maintaining high porosity. Furthermore, it achieves high apparent porosity (without or with minimal use of pore-forming agents). Simultaneously, this invention fully leverages the production of porous slag ceramic materials from high-iron ore waste, possessing high porosity, high apparent porosity, and high flexural strength. This solves the problem of reduced flexural strength and porosity in porous ceramics when using low-quality, complex-composition slag.

[0023] 3. The process of this invention is simple, easy to operate, and highly controllable, making it suitable for large-scale production. Moreover, by using a large amount of high-iron ore waste slag as raw material to prepare porous ceramic materials with high porosity, and applying these materials to manufacture ceramic membrane products, the production cost of ceramic membranes can be significantly reduced. At the same time, through the utilization of slag waste, green, low-carbon and environmentally friendly social benefits can be achieved. Attached Figure Description

[0024] Figure 1 This is a 10 μm electron microscope image of the tubular ceramic film material obtained in Example 1.

[0025] Figure 2 These are images of the green body and the fired sample obtained in Example 3. Implementation

[0026] The present invention is further illustrated by the following examples, but these are not intended to limit the invention. Specific experimental conditions and methods not specified in the following examples are generally conventional methods well known to those skilled in the art.

[0027] Example 1: A method for preparing porous ceramics using high-iron slag, comprising the following steps:

[0028] (1) First, put the high-iron slag powder and water into a ball mill for grinding. When the particle size of the material in the ball mill reaches 100 micrometers, then add methacrylamide and N,N-methylenebisacrylamide in sequence for grinding. Then pass the mixture through a 150-mesh sieve to obtain a slurry. The weight ratio of the high-iron slag powder, methacrylamide, N,N-methylenebisacrylamide and water is 100:3.33:0.8:44.

[0029] The high-speed ore slag powder comprises the following components by mass fraction: silicon dioxide 43.05%, aluminum oxide 11.47%, ferric oxide 16.88%, calcium oxide 15.53%, magnesium oxide 4.52%, sulfur trioxide 4.24%, and other oxides and loss on ignition totaling 4.31%; the high-speed ore slag powder is obtained by crushing high-speed ore slag, and the particle size of the high-speed ore slag powder is 120 micrometers;

[0030] (2) Take ammonium persulfate and N,N,N,N-tetramethylethylenediamine and add them to water in sequence. Then stir and mix them at a speed of 200 r / min to obtain a mixture. The weight ratio of ammonium persulfate, N,N,N,N-tetramethylethylenediamine and water is 7:3:50. The weight ratio of methacrylamide and ammonium persulfate in step (1) is 100:14.

[0031] (3) Add the mixture obtained in step (2) to the slurry obtained in step (1), and then stir and mix evenly at a speed of 300 r / min. Pour the mixture into the mold, and after the slurry in the mold has solidified, dry and demold to obtain the blank of the tubular ceramic film.

[0032] (4) The green body is dried at 60°C, and the moisture content of the dried green body is 2%. Then it is fired in a kiln at a maximum firing temperature of 1130°C for 3 hours. After firing, it is cooled to obtain a tubular ceramic membrane. The tubular ceramic membrane has a flexural strength of 120 MPa, an apparent porosity of 46%, an average filtration pore size of 1.5 micrometers, and an air flux of 200 M. 3 / M 2 ·h·ba.

[0033] Example 2: A method for preparing porous ceramics using high-iron slag, comprising the following steps:

[0034] (1) First, put the high-iron slag powder and water into a ball mill for grinding. When the particle size of the material in the ball mill reaches 150 micrometers, then add methacrylamide and N,N-methylenebisacrylamide in sequence for grinding. Then pass through a 150-mesh sieve to obtain a slurry. The weight ratio of the high-iron slag powder, methacrylamide, N,N-methylenebisacrylamide and water is 100:6:3:30.

[0035] The high-speed ore slag powder comprises the following components by mass fraction: 30% silicon dioxide, 8% aluminum oxide, 22% ferric oxide, 20% calcium oxide, 8% magnesium oxide, 6% sulfur trioxide, and other oxides and loss on ignition totaling 6%; the high-speed ore slag powder is obtained by crushing high-speed ore slag, and the particle size of the high-speed ore slag powder is 150 micrometers.

[0036] (2) Take ammonium persulfate and N,N,N,N-tetramethylethylenediamine and add them to water in sequence. Then stir and mix them at a speed of 150 r / min to obtain a mixture. The weight ratio of ammonium persulfate, N,N,N,N-tetramethylethylenediamine and water is 18:9:50. The weight ratio of methacrylamide and ammonium persulfate in step (1) is 100:20.

[0037] (3) Add foaming agent to the slurry obtained in step (1) and stir at a speed of 300 r / min to form a large number of bubbles in the slurry. Then add the mixture obtained in step (2) to the slurry and stir evenly at a speed of 200 r / min. Pour the mixture into a mold and wait for the slurry in the mold to solidify. Then dry and demold to obtain the blank of the porous ceramic sound-absorbing board. The weight of the foaming agent is 8% of the weight of the high-iron slag powder in step (1). The foaming agent is a combination of hydrogen peroxide and animal protein, and the weight ratio of hydrogen peroxide to animal protein is 5:3.

[0038] (4) The blank is dried at 50°C. The moisture content of the dried blank is 2%. Then it is placed in a kiln for firing. The blank is kept at the highest firing temperature of 1250°C for 1 hour. After firing, it is cooled to obtain a porous ceramic sound-absorbing plate. The flexural strength of the porous ceramic sound-absorbing plate is 25MPa, the apparent porosity is 80%, the specific gravity is 0.5, the average pore diameter of macropores (bubbles) is 2-3 mm, and the average pore diameter of micropores is 20-40 micrometers.

[0039] Example 3: A method for preparing porous ceramics using high-iron slag, comprising the following steps:

[0040] (1) First, put the high-iron slag powder and water into a ball mill for grinding. When the particle size of the material in the ball mill reaches 80 micrometers, then add methacrylamide and N,N-methylenebisacrylamide in sequence for grinding. Then pass through a 150-mesh sieve to obtain a slurry. The weight ratio of the high-iron slag powder, methacrylamide, N,N-methylenebisacrylamide and water is 100:2:0.5:30.

[0041] The high-speed ore slag powder comprises the following components by mass fraction: 55% silicon dioxide, 18% aluminum oxide, 10% ferric oxide, 10% calcium oxide, 2% magnesium oxide, 3% sulfur trioxide, and other oxides and loss on ignition totaling 2%; the high-speed ore slag powder is obtained by crushing high-speed ore slag, and the particle size of the high-speed ore slag powder is 300 micrometers.

[0042] (2) Take ammonium persulfate and N,N,N,N-tetramethylethylenediamine and add them to water in sequence. Then stir and mix them at a speed of 200 r / min to obtain a mixture. The weight ratio of ammonium persulfate, N,N,N,N-tetramethylethylenediamine and water is 15:3:35. The weight ratio of methacrylamide and ammonium persulfate in step (1) is 100:5.

[0043] (3) Add the mixture obtained in step (2) to the slurry obtained in step (1), and then stir and mix evenly at a speed of 350 r / min. Then add the foaming agent and continue stirring and mixing evenly until a large number of bubbles are formed in the slurry. Pour the mixture into a mold, and after the slurry in the mold has solidified, dry and demold to obtain the blank of the porous ceramic wall lightweight brick. See Figure 2 The foaming agent is 5% of the weight of the high-speed iron slag powder in step (1); the foaming agent is a combination of sodium dodecylbenzenesulfonate and triethanolamine lauryl sulfate, and the weight ratio of sodium dodecylbenzenesulfonate to triethanolamine lauryl sulfate is 2:3.

[0044] (4) The green body is dried at 70°C, and the moisture content of the dried green body is 2.5%. Then it is fired in a kiln at the highest firing temperature of 1200°C for 2 hours. After firing, it is cooled to obtain porous ceramic lightweight wall bricks. See [link to relevant documentation]. Figure 2 The porous ceramic wall lightweight brick has a flexural strength of 20 MPa, an apparent porosity of 70%, a specific gravity of 0.65, an average pore diameter of macropores (bubbles) of 0.3–1.5 mm, and an average pore diameter of micropores of 30–50 micrometers.

[0045] Example 4: A method for preparing porous ceramics using high-iron slag, comprising the following steps:

[0046] (1) A certain high-iron ore slag was selected, whose chemical composition was: silicon oxide 16.58%, aluminum oxide 6.48%, ferric oxide 27.57%, calcium oxide 13.97%, titanium oxide 4.14%, sodium oxide 0.65%, and other oxides and loss on ignition totaled 30.61%. Because the content of silicon dioxide, aluminum oxide, and ferric oxide deviates from the composition range of the high-iron slag powder, namely: silicon dioxide 30-55%, aluminum oxide 8-18%, ferric oxide 10-22%, and calcium oxide 10-20%, in order to make the chemical composition of the slag meet the requirements for use, 300 kg of clay, 80 kg of quartz, and 100 kg of limestone are added to 1 ton of slag. After ball milling and mixing, the average particle size reaches 80 micrometers. The main chemical composition of the composite slag after formulation and processing is: silicon dioxide 31.44%, aluminum oxide 12.35%, ferric oxide 18.63%, and calcium oxide 13.36%, which meets the chemical composition requirements for preparing porous high-iron slag ceramics.

[0047] (2) The composite high-iron slag powder, methacrylamide, N,N-methylenebisacrylamide and water prepared in step (1) are put into a ball mill for grinding, and then passed through a 150-mesh sieve to obtain a slurry. The weight ratio of the high-iron slag powder, methacrylamide, N,N-methylenebisacrylamide and water is 100:4:1.5:37.

[0048] (3) Take ammonium persulfate and N,N,N,N-tetramethylethylenediamine and add them to water in sequence. Then stir and mix them at a speed of 300 r / min to obtain a mixture. The weight ratio of ammonium persulfate, N,N,N,N-tetramethylethylenediamine and water is 2:1:10. The weight ratio of methacrylamide and ammonium persulfate in step (2) is 10:1.

[0049] (4) Add the mixture obtained in step (3) to the slurry obtained in step (2), and then stir and mix evenly at a speed of 400 r / min. Then add the foaming agent and continue to stir and mix evenly until a large number of bubbles are formed in the slurry. Pour the mixture into a mold and wait for the slurry in the mold to solidify. Then dry and demold to obtain the green body of the porous ceramic catalyst carrier. The weight of the foaming agent is 0.75% of the weight of the composite high-iron slag powder in step (2). The foaming agent is a combination of sodium dodecylbenzene sulfonate and plant protein. The weight ratio of sodium dodecylbenzene sulfonate to plant protein is 1:1.5.

[0050] (5) The green body is dried at 80°C. The moisture content of the dried green body is 2.5%. Then it is placed in a kiln for firing. The firing temperature is 1050°C for 3 hours. After firing, it is cooled to obtain a porous ceramic catalyst carrier. The porous ceramic catalyst carrier has a flexural strength of 18MPa, an apparent porosity of 63%, a specific gravity of 0.75, an average pore size of macropores (bubbles) of 0.1 to 0.5 mm, and an average pore size of micropores of 20 to 40 micrometers.

[0051] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing porous ceramics using high iron slag, characterized by: It comprises the following steps: (1) Put high-iron slag powder and water into a ball mill for grinding, when the particle size of the material in the ball mill reaches 20-200 microns, then add methacrylamide and N, N-methylene bisacrylamide successively for grinding, then pass through a 150-mesh screen to obtain a slurry, the weight ratio of the high-iron slag powder, methacrylamide, N, N-methylene bisacrylamide and water is 100:(2-6):(0.5-3):(30-45); The high-iron slag powder is obtained by crushing high-iron slag, the particle size of the high-iron slag powder is not higher than 300 microns; the high-iron slag powder comprises the following components with the following mass fractions: silicon oxide 30-55%, aluminum oxide 8-18%, ferric oxide 10-22%, calcium oxide 10-20%, magnesium oxide 2-8%, and other oxides and loss on ignition, which account for 5-13% in total; (2) Put ammonium persulfate and N, N, N, N-tetramethyl ethylenediamine successively into water, then stir and mix under the condition that the speed is 150-300 r / min to obtain a mixed solution, the weight ratio of ammonium persulfate, N, N, N, N-tetramethyl ethylenediamine and water is (5-20):(1-10):(10-100), and the weight ratio of methacrylamide and ammonium persulfate in step (1) is 100:(5-20); (3) Put the mixed solution obtained in step (2) into the slurry obtained in step (1) and stir and mix uniformly under the condition that the speed is 200-400 r / min, then add a foaming agent and continue to stir and mix uniformly, so that a large number of bubbles are formed in the slurry, then pour the slurry into a mold, after the slurry in the mold is solidified, dry and demold to obtain a blank, the weight of the foaming agent is 0.5-8% of the weight of the high-iron slag powder in step (1); (4) Dry the blank obtained in step (3) at 50-80℃, the water content of the dried blank is less than 3%, put it into a kiln for firing, keep the highest firing temperature at 1050-1250℃ for 1-3h, after the firing is completed, cool to obtain a porous ceramic.

2. The method for preparing porous ceramics using high-iron slag according to claim 1, characterized by: If the contents of silicon oxide, aluminum oxide, calcium oxide and ferric oxide in the high-iron slag powder do not meet the composition requirements of the high-iron slag powder in claim 1, add natural minerals, the natural minerals are one or a combination of several of quartz, clay, limestone and red mud.

3. The method for preparing porous ceramics using high-iron slag according to claim 1, characterized by: The foaming agent is one or a combination of several of sodium dodecyl benzene sulfonate, hydrogen peroxide, animal protein, plant protein and triethanolamine lauryl sulfate.

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