Composite tailing foaming material prepared based on dual foaming system and preparation method of composite tailing foaming material

Abstract

The invention discloses a composite tailing foaming material prepared based on a dual foaming system and a preparation method thereof, and belongs to the technical field of solid waste resource utilization and building materials. The composite tailing foaming material prepared based on the double foaming system comprises the following components in parts by mass: 40-50 parts of iron tailings, 20-30 parts of copper tailings, 25-35 parts of a fluxing agent, 15-25 parts of water and 0.7-1.2 parts of a foaming agent. The preparation method comprises the following steps: carrying out ball milling and sieving pretreatment on the tailings and other raw materials; a proper amount of raw materials are weighed according to a used formula and fully mixed, and a primary foaming system is established by taking lauryl sodium sulfate and polyvinyl alcohol as dominant materials; calcining by using a proper firing system, and establishing a secondary foaming system by using silicon carbide as a dominant material; and naturally cooling to obtain the foaming material. The dual foaming system realizes an efficient and controllable foaming process through temperature gradient regulation and control and multi-mechanism cooperation, and finally the foamed ceramic material with a uniform pore structure and excellent performance is prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource utilization and building materials, and particularly relates to a composite tailings foam material prepared based on a double foaming system and a preparation method thereof. Background Art

[0002] In recent years, vigorously carrying out research on energy-saving and low-carbon building materials has gradually become a development trend. As an emerging green energy-saving wall material, foamed ceramics have the characteristics of light weight, high strength and excellent thermal insulation performance.

[0003] Existing ceramic foaming technologies mostly use a single chemical or physical foaming system. Chemical foaming relies on the decomposition of aluminum powder or hydrogen peroxide to produce gas. Although the expansion rate is high (up to 300%), the reaction rate is difficult to control. Physical foaming mainly uses surfactants (such as sodium lauryl sulfate) or protein-based foaming agents. Although the foam pores are relatively uniform (pore size 50-300μm), the foaming ratio is usually less than 50%, and the foam half-life is less than 20 minutes.

[0004] The Chinese invention patent application with application number CN202310432084.5 discloses an alumina ceramic and its preparation method. Alumina, Suzhou clay and calcined bauxite are used as the main raw materials, and sodium lauryl sulfate solution and other reagents are used to sinter the foamed ceramic at 1500-1550°C. The foamed ceramic has a bulk density of 1.03-2.42 kg / m 3 , with a porosity of 33.14% to 52.36%. This preparation method has many problems: First, sodium dodecyl sulfate (SDS) decomposes at a low temperature, preventing continuous gas production during the subsequent high-temperature stage. This causes the bubbles that have already formed to collapse due to gas escape during the high-temperature melting stage, making it impossible to maintain the pore structure. Ultimately, the material density increases and the porosity decreases. Second, the gas produced by the decomposition of the organic foaming agent is concentrated in the low-temperature stage, when the slurry has not yet softened, and the bubbles are prone to merging or rupturing. Third, the pores formed at the low temperature stage may lack connectivity due to poor melt fluidity, resulting in increased brittleness of the material.

[0005] The Chinese invention patent application with application number CN202410951239.0 discloses a foamed ceramic based on copper-molybdenum tailings and its preparation method. The foamed ceramic is prepared by using copper-molybdenum tailings, potassium feldspar, sodium carbonate, and waste glass as the main raw materials, using silicon carbide and other foaming agents to assist foaming, and sintering at 940-990°C. The apparent density of the foamed ceramic is 0.48-0.82 kg / m 3, with a compressive strength of 4.77 to 25.75 MPa. This preparation method has many problems: First, SiC reacts with oxides to produce gas only at high temperatures; no bubbles form at low temperatures. This results in gas escape when the viscosity of the high-temperature melt is too low, making it difficult to form stable and evenly distributed pores, and prone to large or closed-pore structures. Second, if the heating rate is improperly controlled, the SiC gas production rate may exceed the melt's encapsulation capacity, causing bubbles to merge or rupture. Third, higher temperatures and longer holding times are required to complete foaming, increasing energy consumption and production costs.

[0006] Tailings are solid waste remaining after ore has been processed through the mineral processing process. They are mainly composed of fine-grained rocks, mineral residues and mineral processing reagents. With the large-scale development of global mineral resources, the problem of tailings storage is becoming increasingly serious. The use of tailings in the preparation of lightweight foaming materials for application in the field of building materials is expected to further increase the recycling rate of tailings, such as the Chinese invention patent application with application number CN202311007273.4, but the existing technology has significant limitations. On the one hand, the tailings themselves lack gelling activity, and when the addition amount exceeds 50%, it will cause the compressive strength of the material to drop sharply. On the other hand, the density heterogeneity of tailings particles (usually 2.8 to 4.5 g / cm 3 ) and a wide particle size distribution (D50 = 10-200 μm) lead to poor bubble stability during the foaming process, which is manifested as bubble merging to form millimeter-scale macropores (pore diameter > 800 μm) or local collapse to form structural defects. Summary of the Invention

[0007] In response to the above problems, the present invention provides a composite tailings foam material prepared based on a double foaming system and a preparation method thereof. This double foaming system realizes an efficient and controllable foaming process through temperature gradient regulation and multi-mechanism collaboration, and ultimately produces a foam material with uniform pore structure and excellent performance.

[0008] To achieve the above object, the present invention is implemented through the following technical solutions:

[0009] The invention provides a composite tailings foaming material prepared based on a double foaming system. The composite tailings foaming material comprises the following components, calculated by weight: 40 to 50 parts of iron tailings, 20 to 30 parts of copper tailings, 25 to 35 parts of flux, 15 to 25 parts of water and 0.7 to 1.2 parts of foaming agent.

[0010] In the preferred embodiment, the mass ratio of the iron tailings to the copper tailings is 40:30.

[0011] In a preferred embodiment, the flux is composed of a mixture of waste glass and sodium carbonate. Waste glass melts at high temperatures to form a silicate liquid phase, lowering the melting temperature and increasing the melt viscosity. Sodium carbonate further promotes the formation of a low-temperature liquid phase, forming a viscous glassy matrix that provides mechanical support for the bubbles. The flux also promotes viscosity-temperature matching: during the high-temperature stage of SiC foaming, the moderate melt viscosity allows bubbles to expand effectively and resist merging or rupturing.

[0012] In a further preferred embodiment, the mass fraction of waste glass in the flux is 75% to 90%, the balance is sodium carbonate, and the sum of the mass fractions of waste glass and sodium carbonate is 100%.

[0013] In a preferred embodiment, the foaming agent comprises two systems, the first system comprises 0.2 to 0.5 parts of sodium dodecyl sulfate (SDS) and 0.1 to 0.4 parts of polyvinyl alcohol (PVA), and the second system comprises 0.3 to 0.4 parts of silicon carbide (SiC).

[0014] The double foaming system cleverly plays the synergistic role of the foaming agents in different stages. Among them, the low-temperature stage (dominated by SDS and PVA): in the early stage of ball milling and calcination, PVA stabilizes the bubbles in the slurry through its surface activity to form initial pores. SDS decomposes at a lower temperature, releasing gas, and together with PVA forms an initial bubble network. The high-temperature stage (dominated by SiC): when the temperature rises to above 800°C, PVA has completely decomposed, but at this time SiC begins to react with metal oxides or oxygen in the tailings to generate CO2 or CO gas. The reaction temperature of SiC is synchronized with the melt formation temperature. At this time, the melt is in a viscous semi-molten state, which is conducive to its effective encapsulation of gas and inhibition of bubble escape.

[0015] In a further preferred embodiment, the foaming agent comprises 0.35 parts of silicon carbide, 0.35 parts of sodium lauryl sulfate and 0.25 parts of polyvinyl alcohol.

[0016] In the preferred embodiment, the composite tailings foam material prepared based on the double foaming system has an apparent porosity of 5.74%, a total porosity of 72.75%, and an apparent density of 0.645 g / cm 3 , compressive strength is 10.48MPa, and thermal conductivity is 0.125W / (m·K).

[0017] The present invention also provides a method for preparing the composite tailings foam material based on the double foaming system, comprising the following steps:

[0018] S1: ball milling the iron tailings and copper tailings respectively;

[0019] S2: mixing the iron tailings after ball milling in step S1, the copper tailings after ball milling in step S1, a flux, water and a foaming agent to prepare a slurry;

[0020] S3: evenly spreading the slurry obtained in step S2 in a mold, compacting the surface, calcining, and naturally cooling to obtain the composite tailings foaming material.

[0021] In a preferred embodiment, the ball milling in step S1 has a rotation speed of 300 to 450 rpm and a duration of 15 to 45 minutes.

[0022] In a preferred embodiment, the iron tailings and copper tailings after ball milling in step S1 are passed through a 120-mesh nylon sieve.

[0023] In a preferred embodiment, the calcination process in step S3 is as follows: heating to 750-850°C at 8-12°C / min, then heating to 1050-1100°C at 2-8°C / min, and finally keeping the temperature for 10-40 minutes.

[0024] The rapid heating phase rapidly passes through the decomposition temperature range of PVA and SDS, utilizing their short-term effects to form initial bubbles and prevent gas loss due to excessive decomposition. The slow heating phase slows the heating rate, allowing the SiC to slowly release gas as the melt gradually forms. Due to the increased melt viscosity at this time, bubbles can be effectively encapsulated. The holding phase stabilizes the melt viscosity through heat preservation, and due to surface tension, bubbles are evenly distributed and fixed.

[0025] In a further preferred embodiment, during the calcination process in step S3, the temperature is increased to 1070° C. at a rate of 4° C. / min.

[0026] In a further preferred embodiment, during the calcination process in step S3, the holding time is 25 minutes.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The conventional firing process in the production of foam materials rarely enables the foam materials to maintain high compressive strength at a low apparent density. However, the present invention can not only achieve a compressive strength far exceeding the corresponding standard, but also has the excellent performance of extremely low thermal conductivity.

[0029] 2. The present invention uses a composite material of iron and copper tailings as raw material, rather than a single tailing. This can fully utilize the advantages of both tailings and compensate for their respective deficiencies, thereby producing a foam material with better performance. Specifically, the iron in the iron tailings can improve the mechanical strength of the foam material, while the copper and zinc in the copper tailings can improve the product's oxidation resistance while maintaining mechanical strength.

[0030] 3. The flux used in the present invention contains a certain amount of waste glass. Waste glass is not only widely available and low in cost, but also environmentally friendly and pollution-free, thus enabling the recycling of resources.

[0031] 4. The present invention adopts a double foaming system to prepare tailings foaming material. In the first round of foaming, sodium lauryl sulfate is used to obtain a slurry that is conducive to foaming, and the property of polyvinyl alcohol to form a network structure in water is used to assist sintering; the second round of foaming is carried out by foaming bubbles generated by silicon carbide at high temperature, which replenishes bubbles to a greater extent to ensure the foaming effect, and the first round of foaming system can be used to stabilize the foaming, thereby further improving the foaming efficiency.

[0032] 5. The present invention's optimized preparation process precisely controls the matching relationship between melt viscosity and foaming rate by adjusting the flux ratio and heating rate. Setting the holding time ensures sufficient bubble growth and stability, preventing excessive expansion or collapse. This makes the production of foamed materials more efficient and scientific.

[0033] 6. The present invention achieves a high tailings utilization rate of 70%. The preparation method is simple, easy to operate, and suitable for large-scale production. The entire preparation process does not require complex equipment and technology, only ordinary ball mills and kilns, making it suitable for promotion and application in small enterprises near mining areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the SEM image (500 times) of the sample in Example 6. DETAILED DESCRIPTION

[0035] The following is a detailed description of the embodiments of the present invention in conjunction with the embodiments. It should be noted that the embodiments described are only partial examples of the present invention, and based on the technical concept of the present invention, other embodiments that can be obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0036] Example 1

[0037] A composite tailings foaming material prepared based on a double foaming system comprises the following components, calculated by mass: 45 parts of iron tailings, 25 parts of copper tailings, 25 parts of waste glass, 5 parts of sodium carbonate, 20 parts of water, 0.35 parts of silicon carbide, 0.35 parts of sodium lauryl sulfate and 0.25 parts of polyvinyl alcohol.

[0038] The method for preparing the composite tailings foam material based on the double foaming system comprises the following steps:

[0039] S1: The iron tailings and copper tailings were ball milled for 30 min at a speed of 360 rpm and passed through a 120-mesh nylon sieve;

[0040] S2: Weigh the iron tailings after ball milling in step S1, the copper tailings after ball milling in step S1, waste glass, sodium carbonate, water, silicon carbide, sodium lauryl sulfate and polyvinyl alcohol according to mass parts and mix them evenly to prepare a slurry;

[0041] S3: evenly spread the slurry prepared in step S2 in a mold, compact the surface, heat it to 800° C. at 10° C. / min, then heat it to 1070° C. at 5° C. / min, keep it warm for 20 minutes, and cool it naturally to obtain the composite tailings foam material.

[0042] The performance of this embodiment is shown in Table 1.

[0043] Example 2

[0044] A composite tailings foaming material prepared based on a double foaming system, the components of which are basically the same as those in Example 1, with the only difference being that the material contains 40 parts of iron tailings and 30 parts of copper tailings.

[0045] The preparation method of the composite tailings foam material based on the double foaming system is the same as that in Example 1.

[0046] The performance of this comparative example is shown in Table 1.

[0047] Comparative Example 1

[0048] A composite tailings foaming material prepared based on a double foaming system, the components of which are basically the same as those in Example 1, except that the material contains 35 parts of iron tailings and 35 parts of copper tailings.

[0049] The preparation method of the composite tailings foam material based on the double foaming system is the same as that in Example 1.

[0050] The performance of this comparative example is shown in Table 1.

[0051] Table 1 Differences in raw materials and corresponding properties between Examples 1 to 2 and Comparative Example 1

[0052]

[0053] As can be seen from Table 1, when the total tailings content is 70%, iron tailings is the component with the highest melting point in the mixture. As the iron tailings content decreases, the apparent density of the sample decreases, and the compressive strength decreases significantly. Although the total porosity increases, the closed porosity may not change significantly. For example, in Comparative Example 1, although the apparent density decreases due to the small amount of iron tailings added, the compressive strength is too low, and the balance between apparent density and compressive strength is not well maintained. In comparison, the various properties of Example 2 are more balanced.

[0054] Example 3

[0055] A composite tailings foaming material prepared based on a double foaming system comprises the following components, calculated by mass: 40 parts of iron tailings, 30 parts of copper tailings, 25 parts of waste glass, 5 parts of sodium carbonate, 20 parts of water, 0.35 parts of silicon carbide, 0.35 parts of sodium lauryl sulfate and 0.25 parts of polyvinyl alcohol.

[0056] The method for preparing the composite tailings foam material based on the double foaming system comprises the following steps:

[0057] S1: The iron tailings and copper tailings were ball milled for 30 min at a speed of 360 rpm and passed through a 120-mesh nylon sieve;

[0058] S2: Weigh the iron tailings after ball milling in step S1, the copper tailings after ball milling in step S1, waste glass, sodium carbonate, water, silicon carbide, sodium lauryl sulfate and polyvinyl alcohol according to mass parts and mix them evenly to prepare a slurry;

[0059] S3: evenly spread the slurry prepared in step S2 in a mold, compact the surface, heat it to 800° C. at 10° C. / min, then heat it to 1070° C. at 5° C. / min, keep it warm for 10 minutes, and cool it naturally to obtain the composite tailings foam material.

[0060] The performance of this embodiment is shown in Table 2.

[0061] Example 4

[0062] A composite tailings foam material prepared based on a double foaming system, the components of which are consistent with those in Example 3.

[0063] The preparation method of the composite tailings foam material based on the double foaming system is basically the same as that of Example 3, with the only difference being that the insulation time in step S3 is 25 minutes.

[0064] The performance of this comparative example is shown in Table 1.

[0065] The preparation steps are the same as those in Example 3. The detailed firing system differences and corresponding properties are shown in Table 2.

[0066] Table 2 Differences in holding time and corresponding performance of Examples 3 to 4

[0067]

[0068] Table 2 shows that as the holding time increases, the blowing agent fully expands at high temperatures, resulting in a slow increase in the apparent porosity of the sample, while the total porosity increases significantly. It is conceivable that continued holding would result in little change in the total porosity, destroying the original closed-cell structure and transforming it into an open-cell structure. Simultaneously, the apparent density and compressive strength would gradually decrease.

[0069] Example 5

[0070] A composite tailings foaming material prepared based on a double foaming system comprises the following components, calculated by mass: 40 parts of iron tailings, 30 parts of copper tailings, 25 parts of waste glass, 5 parts of sodium carbonate, 20 parts of water, 0.35 parts of silicon carbide, 0.35 parts of sodium lauryl sulfate and 0.25 parts of polyvinyl alcohol.

[0071] The method for preparing the composite tailings foam material based on the double foaming system comprises the following steps:

[0072] S1: The iron tailings and copper tailings were ball milled for 30 min at a speed of 360 rpm and passed through a 120-mesh nylon sieve;

[0073] S2: Weigh the iron tailings after ball milling in step S1, the copper tailings after ball milling in step S1, waste glass, sodium carbonate, water, silicon carbide, sodium lauryl sulfate and polyvinyl alcohol according to mass parts and mix them evenly to prepare a slurry;

[0074] S3: evenly spread the slurry prepared in step S2 in a mold, compact the surface, heat it to 800° C. at 10° C. / min, then heat it to 1070° C. at 2° C. / min, keep it warm for 25 minutes, and cool it naturally to obtain the composite tailings foam material.

[0075] The performance of this embodiment is shown in Table 3.

[0076] Example 6

[0077] A composite tailings foam material prepared based on a double foaming system, the components of which are consistent with those in Example 5.

[0078] The preparation method of the composite tailings foam material based on the double foaming system is basically the same as that of Example 5, with the only difference being that the temperature is raised to 1070° C. at 4° C. / min in step S3.

[0079] The performance of this embodiment is shown in Table 3.

[0080] Example 7

[0081] A composite tailings foam material prepared based on a double foaming system, the components of which are consistent with those in Example 5.

[0082] The preparation method of the composite tailings foam material based on the double foaming system is basically the same as that of Example 5, with the only difference being that the temperature is raised to 1070° C. at 6° C. / min in step S3.

[0083] The performance of this embodiment is shown in Table 3.

[0084] Example 8

[0085] A composite tailings foam material prepared based on a double foaming system, the components of which are consistent with those in Example 5.

[0086] The preparation method of the composite tailings foam material based on the double foaming system is basically the same as that of Example 5, with the only difference being that the temperature is raised to 1070° C. at 8° C. / min in step S3.

[0087] The performance of this embodiment is shown in Table 3.

[0088] Table 3 Differences in terminal heating rates and corresponding performances of Examples 5 to 8

[0089]

[0090] As shown in Table 3, as the heating rate accelerates, the apparent density of the sample first decreases and then increases. This is because the heating rate affects the synchronization between the decomposition of the blowing agent and the formation of bubbles. If the temperature is raised too slowly, bubbles may escape prematurely, the porosity decreases, and the thermal conductivity increases. If the temperature is raised too quickly, the decomposition of the blowing agent lags, resulting in uneven bubble distribution, coarse or broken pores, the formation of interconnected pores, and an increase in thermal conductivity. Overall, the performance of the sample in Example 6 is better.

[0091] Figure 1 is the SEM image of the sample of Example 6, Figure 1 It can be seen that the pore wall of the sample in Example 6 is relatively thin, the overall pore size is relatively uniform, a small part presents alternating large and small pores, and only a small number of clumps and clusters of crystals are attached to the pores.

[0092] The above embodiments are merely specific examples of the present invention. Those skilled in the art will understand that any extension of the technical effects achieved through material substitution, parameter adjustment, or other methods based on the dual foaming system of the present invention falls within the substantive scope of the present invention. Any technical solutions achieved through equivalent substitution or adaptive modification based on the dual foaming system of the present invention should be included within the scope of protection defined by the claims and their equivalents.

Claims

1. A composite tailings foam material prepared based on a double foaming system, characterized in that: The invention comprises the following components in parts by mass: 40 to 50 parts of iron tailings, 20 to 30 parts of copper tailings, 25 to 35 parts of flux, 15 to 25 parts of water and 0.7 to 1.2 parts of foaming agent.

2. The composite tailings foam material prepared based on the double foaming system according to claim 1, characterized in that, The mass ratio of the iron tailings to the copper tailings is 40:

30.

3. The composite tailings foam material prepared based on the double foaming system according to claim 1, characterized in that, The flux is composed of a mixture of waste glass and sodium carbonate.

4. The composite tailings foam material prepared based on the double foaming system according to claim 3, characterized in that, The mass fraction of the waste glass in the flux is 75% to 90%, the balance is sodium carbonate, and the sum of the mass fractions of the waste glass and sodium carbonate is 100%.

5. The composite tailings foam material prepared based on the double foaming system according to claim 1, characterized in that, The foaming agent comprises two systems. The first system comprises 0.2-0.5 parts of sodium lauryl sulfate and 0.1-0.4 parts of polyvinyl alcohol, and the second system comprises 0.3-0.4 parts of silicon carbide.

6. The composite tailings foam material prepared based on the double foaming system according to claim 5, characterized in that, The foaming agent comprises 0.35 parts of silicon carbide, 0.35 parts of sodium lauryl sulfate and 0.25 parts of polyvinyl alcohol.

7. A method for preparing a composite tailings foam material based on a double foaming system as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: S1: ball milling the iron tailings and copper tailings respectively; S2: mixing the iron tailings after ball milling in step S1, the copper tailings after ball milling in step S1, a flux, water and a foaming agent to prepare a slurry; S3: evenly spreading the slurry obtained in step S2 in a mold, compacting the surface, calcining, and naturally cooling to obtain the composite tailings foaming material.

8. The method for preparing a composite tailings foam material prepared based on a double foaming system according to claim 7, wherein: The ball milling in step S1 has a rotation speed of 300 to 450 rpm and a duration of 15 to 45 minutes.

9. The method for preparing a composite tailings foam material prepared based on a double foaming system according to claim 7, wherein: The iron tailings and copper tailings after ball milling in step S1 are passed through a 120-mesh nylon sieve.

10. The method for preparing a composite tailings foam material based on a double foaming system according to claim 7, wherein: The calcination process in step S3 is as follows: heating to 750-850° C. at 8-12° C. / min, then heating to 1050-1100° C. at 2-8° C. / min, and finally keeping the temperature for 10-40 minutes.

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