Curing agent based on silicon aluminum zincate sol system and graphite tailing sand curing method

Abstract

The invention discloses a curing agent based on a silicon aluminum zincate sol system and a graphite tailing sand curing method. The curing agent comprises a sol solution and ZnO, wherein the sol solution is prepared from any one or a mixture of more than two of sodium water glass or potash water glass, NaOH or KOH, aluminum sulfate, aluminum chloride and aluminum nitrate; when the graphite tailing sand needs to be solidified, the graphite tailing sand with the water content smaller than 30% is taken, the sol solution with the weight being 30%-50% of that of the graphite tailing sand is added, and ZnO with the weight being 3%-8% of that of the graphite tailing sand is added after even stirring; and mold shaping and curing demolding only need 1-2 h at the room temperature. In the preparation process of the curing agent, 'three wastes' are not discharged, the addition amount is small, the cost for curing the graphite tailing sand is relatively low, the strength of a cured product is higher, and the compressive strength of a 30-day sample and the compressive strength of a 90-day sample are 34-45 MPa and 50-66 MPa respectively and are obviously superior to those of an existing curing material.

Description

Technical Field

[0001] The invention belongs to the technical field of curing agents, relates to the treatment of waste tailings sand in the mining industry, and particularly relates to a curing agent based on a silicon aluminum zincate sol system and a graphite tailings sand curing method. Background Art

[0002] In recent years, with rapid economic development and the transformation and upgrading of industrial structures, the market demand for graphite materials has continued to grow. Graphite's application and production have been particularly increasing in new energy and new materials sectors. However, the graphite beneficiation process generates large quantities of graphite tailings. These byproducts of graphite mining and processing have historically been considered waste and stored in tailings ponds. In fact, due to the particle size of graphite tailings ranging from 200 to 400 mesh, they are highly susceptible to dust emission, posing a significant threat to the environment, human production, and daily life. Promptly treating and minimizing environmental damage has become an urgent issue. The rational utilization of graphite tailings can help conserve resources, improve economic efficiency, better protect the environment, and promote the sustainable development of the graphite mining industry. Therefore, adopting appropriate tailings treatment methods to maximize the value of graphite tailings and minimize their environmental impact has become a widely researched topic. Actively searching for new materials that are environmentally friendly, resource-efficient, and capable of effectively managing graphite tailings is of great significance.

[0003] Currently, adhesives that can be used to solidify graphite tailings include organic resins such as unsaturated resins and epoxy resins. While these materials offer high strength, they are relatively expensive and lack high-temperature resistance. Inorganic materials such as aluminum dihydrogen phosphate (Al(H2PO)3) and low-temperature glass powder are also excellent curing agents for graphite tailings, offering high strength. However, these curing agents require high temperatures and, therefore, are also expensive to prepare. Ordinary Portland cement is also a widely used curing material, but experiments have shown that the strength of products containing 20% cement in the curing process falls far short of the strength of the aforementioned two curing agents, and increasing the amount of cement increases the cost. Oxychloride cement products offer high strength but poor water resistance. Therefore, it is necessary to develop a relatively inexpensive curing agent that produces a relatively high-strength product and can cure graphite tailings at room temperature. Summary of the Invention

[0004] In view of the defects and shortcomings in the prior art, the object of the present invention is to provide a curing agent based on a silicoaluminozincate sol system, which is mainly used for the curing treatment of graphite tailings sand and has the advantages of low preparation cost, high curing efficiency, and high strength of the cured product.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A curing agent based on a silicoaluminozincate sol system comprises a sol solution prepared from sodium water glass or potassium water glass, NaOH or KOH, any one of aluminum sulfate, aluminum chloride, and aluminum nitrate, or a mixture of two or more thereof, and ZnO.

[0007] As a preferred embodiment of the present invention, the preparation method of the curing agent comprises the following steps:

[0008] (1) Weigh sodium water glass or potassium water glass and set aside;

[0009] (2) Weigh any one of aluminum sulfate, aluminum chloride, and aluminum nitrate, or a mixture of two or more thereof, and add water to form a clear solution;

[0010] (3) Weigh NaOH or KOH and add water to make a clear solution;

[0011] (4) Weigh ZnO and set aside;

[0012] (5) Take one portion each of the solutions of step (2) and step (3); pour the solution of step (3) into the solution of step (2) while stirring;

[0013] (6) Take one portion each of the solution from step (5) and step (1); pour the solution from step (5) into step (1) under stirring to generate a transparent low molecular weight sol solution;

[0014] Then the sol solution of step (6) and ZnO are used to solidify the graphite tailings sand.

[0015] As a preference of the present invention, the molar number n of the sodium water glass or potassium water glass is ≤2.5.

[0016] As a preferred embodiment of the present invention, in step (1), 40% to 50% of sodium water glass or 40% to 50% of potassium water glass is weighed.

[0017] As a preferred embodiment of the present invention, a 20% to 40% clear solution is prepared in step (2).

[0018] As a preferred embodiment of the present invention, a 20% to 40% clear solution is prepared in step (3).

[0019] As a preferred embodiment of the present invention, in step (5), equal weight portions of the solutions of step (2) and step (3) are taken; and in step (6), equal weight portions of the solutions of step (5) and step (1) are taken.

[0020] The present invention also provides a method for solidifying graphite tailings using the above-mentioned curing agent, which specifically comprises the following steps: taking graphite tailings, adding a sol solution of 30% to 50% by weight of the graphite tailings, wherein the sol solution is the solution of the above-mentioned step (6), stirring evenly, and then adding ZnO of 3-8% by weight of the graphite tailings and mixing evenly; shaping the graphite tailings into a mold at room temperature, and curing and demolding in just 1 to 2 hours.

[0021] As a preferred embodiment of the present invention, the added amount of ZnO is 4-6% of the weight of the graphite tailings sand.

[0022] As a preference of the present invention, the water content of the graphite tailings sand is less than 30%.

[0023] Advantages and beneficial effects of the present invention:

[0024] (1) The curing agent provided by the present invention has the advantages of low preparation cost, high curing efficiency, and high strength of the product after curing. The preparation process of the curing agent does not discharge "three wastes" and the addition amount is small. Therefore, the cost of curing graphite tailings sand is relatively low, which solves the technical problem of high cost of existing curing agents.

[0025] (2) The graphite tailings sand solidified sample using the curing agent of the present invention has a compressive strength of 34 to 45 MPa at 30 days; while the sample block solidified with 30% ordinary Portland cement has a compressive strength of 10 to 15 MPa at 30 days. It can be seen that the curing agent provided by the present invention has a higher strength after curing.

[0026] (3) The present invention designs three types of sol curing agents: SiO2-Al2O3, SiO2-Al2O3-CaO, and SiO2-Al2O3-ZnO. Experiments on the curing of graphite tailings show that the SiO2-Al2O3 sol system takes 5 to 8 hours to cure graphite tailings; the SiO2-Al2O3-CaO system only takes 10 to 20 minutes; and the SiO2-Al2O3-ZnO system takes 1 to 2 hours. Obviously, in the actual production process, 5 to 8 hours is too inefficient to prepare a finished product, while 10 to 20 minutes can only complete the mixing process but cannot achieve the preparation and molding process. Therefore, it can be seen that the 1 to 2 hour curing time of the SiO2-Al2O3-ZnO system is most conducive to achieving a complete preparation process.

[0027] (4) In the present invention, the combined action of Si, Al, and Zn is the optimal combination of curing agents. ZnO can cause linear aluminosilicate oligomer molecules to aggregate and grow within a suitable event range and cross-link into a network structure, forming dense aluminosilicate (SiO2-Al2O3-ZnO) gel aggregates, thereby improving product strength.

[0028] (5) In the graphite tailings sand solidified samples prepared using the curing agent of the present invention, the SiO2-Al2O3-ZnO gel structure transforms into a SiO2-Al2O3-ZnO zeolite crystal structure over time. Experiments show that the compressive strengths of the 7d, 30d, and 90d samples are 10-16 MPa, 34-45 MPa, and 50-66 MPa, respectively. This shows that the graphite tailings sand blocks using this curing agent become increasingly "solid." DETAILED DESCRIPTION

[0029] To make it clearer to those skilled in the art, the technical solution of the present invention is described in detail below. It should be noted that the present invention is not limited to the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0030] As early as the 1940s, researchers discovered that adding a small amount of sodium hydroxide (NaOH) to cement slurry significantly accelerated the hydration reaction of cement. NaOH can quickly dissolve silica-alumina materials and act as a catalyst. Based on this, the "alkali activation" theory was proposed. Subsequent researchers further studied the relevant properties of alkali-activated fly ash cementitious materials: they realized that the properties of the alkali activator (especially the ratio of SiO2 / Na2O) play an important role in the dynamics, structure and composition of the initial formation of hydrated gel, pointed out that the degree of polymerization of SiO2 will also affect the stability of the final polymer, and specifically studied the mechanical properties of alkali-activated slag concrete with water glass, NaOH, sodium carbonate (Na2CO3) as activators and limestone as fine aggregate. The results showed that the strength of alkali-activated slag concrete and ordinary Portland cement fine aggregate concrete is equivalent; in addition, some researchers also investigated the effects of the type, dosage and incorporation form of alkali activators on the strength of alkali-activated pozzolan cementitious materials. The results showed that a mixed activator of water glass and potassium hydroxide (KOH) is the best activator, and there is an optimal range for the dosage of alkaline activators. At the optimal dosage, the activation effect is the best and the strength of the cementitious material is also the highest; through research, The effects of alkali activator and temperature on the setting time of alkali-activated slag cementitious materials showed that compared with ordinary Portland cement, the reaction rate of alkali-activated slag was significantly faster. The setting time of slag activated by sodium silicate (Na2SiO3) solution was the fastest, while the setting times of NaOH and Na2CO3 were moderate. The setting time gradually decreased with increasing temperature (20-31°C). Under the condition of a certain alkali activator dosage, when the water glass modulus was 1.4, the strength of the specimens at all ages was high. When the water glass modulus was fixed and the alkali activator dosage was 4%-12%, the strength of the specimens first increased and then decreased. When the alkali activator dosage was 8%, the strength of the specimens reached its maximum. Appropriately increasing the curing temperature accelerated the rate of hydration reaction and improved the compressive strength of the cementitious material. Kaolin activated with a modulus of 1.0 and an 8% water glass dosage achieved a 3-day compressive strength of 115.6 MPa and a 7-day compressive strength of 131.9 MPa.

[0031] The structural analysis of the hydration reaction mechanism of alkali-activated fly ash cementitious materials at 1d, 3d, 7d, 14d and 28d showed that the glass phase in fly ash dissolved in an alkaline environment, and the -Si-O-Si- and -Si-O-Al- bonds broke during the dissolution process. The broken -Si-O- and -Al-O- bonds reacted with the alkali metal ions Na + , K + With OH - The reaction generates oligomers [—Si—O—Na, —Si—O—Ca—OH, Al(OH)4 - 、Al(OH)5 2- 、Al(OH)63- As the hydration reaction proceeds, the chemical composition and ion concentration in the solution continue to change, and these oligomers Ca 2+ The divalent ions are gradually cross-linked to form a gel-like precursor, and as the reaction continues, its content gradually increases to form a highly dense network space structure.

[0032] The results of the base activation theory have led us to realize that:

[0033] (1) Strong bases such as NaOH and KOH can catalyze the dissolution of active ingredients in silicate mineral powders (such as volcanic ash and fly ash) and aluminate mineral powders (kaolin) in water. The dissolution products exist in the form of low molecular weight Na2SiO3 (—Si—O—Na) or K2SiO3 (—Si—O—K) and NaAlO2 (—Al—O—Na) fragments respectively;

[0034] (2) As the hydration reaction of these oligomer fragments begins, they gradually cross-link to form a gel-like precursor with larger molecular chains. As the reaction continues, the content of the precursor gradually increases to form a dense three-dimensional network structure, thereby solidifying to obtain strength.

[0035] (3) Because kaolin contains a large amount of aluminate components, it has a higher relative activity. The amount of its dissolved -Al-O-Na fragments in the solution is larger, resulting in a denser gel network. In addition, -Si-O-Na fragments and -Al-O-Na fragments can react to form zeolite crystal structures in a strong alkaline environment. Therefore, the strength of its solidified specimens is higher than that of silicate specimens.

[0036] In summary, although the activity of graphite tailings is not as high as that of volcanic ash, fly ash and kaolin, by artificially adding soluble -Si-O-Na fragments and -Al-O-Na fragments into it and simulating the same environmental conditions as alkali-activated kaolin, higher strength test blocks similar to those of alkali-activated kaolin can be obtained.

[0037] The present invention provides a curing agent based on a silicoaluminozincate (SiO2-Al2O3-ZnO) sol system based on the study, recognition and understanding of the research results of predecessors. The curing agent is mainly used as a curing agent for graphite tailings sand. Specifically, the curing agent includes a sol solution prepared from any one of sodium water glass (molar number n≤2.5) or potassium water glass (molar number n≤2.5), NaOH or KOH, aluminum sulfate [Al2(SO4)3] or aluminum chloride [AlCl3] or aluminum nitrate [Al(NO3)3] or a mixture of two or more thereof, and ZnO. The above materials can all be industrial grade purity products.

[0038] In this embodiment, the preparation method of the curing agent includes the following steps:

[0039] (1) Weigh a certain amount of 40% to 50% sodium water glass (mole number n ≤ 2.5) or 40% to 50% potassium water glass (mole number n ≤ 2.5) and place it in a glass, ceramic, enamel, fiberglass or stainless steel container;

[0040] (2) Weigh a certain amount of Al2(SO4)3 or AlCl3 or Al(NO3)3 or a mixture of any two or more of aluminum sulfate, aluminum chloride, and aluminum nitrate, place it into any container mentioned in step (1), and add tap water at room temperature to make a 20% to 40% clear solution;

[0041] (3) Weigh a certain amount of NaOH or KOH into any of the containers mentioned in step (1), and add tap water at room temperature to make a 20% to 40% clear solution;

[0042] (4) Weigh a certain amount of ZnO and set aside;

[0043] (5) Take equal weights of the solutions from step (2) and step (3); slowly pour the solution from step (3) into the solution from step (2) while stirring. Initially, white flocs will form. As the amount of solution from step (3) increases, the flocs dissolve until a clear solution is formed. The main chemical reactions that occur during this process are as follows:

[0044] Al 3+ +OH - →Al(OH)3↓

[0045] Al(OH)3↓+OH - →AlO2 - +HO -

[0046] (6) Take equal weights of the solution from step (5) and the solution from step (1); slowly pour the solution from step (5) into step (1) while stirring to generate a transparent low molecular weight sol solution; the main chemical reactions occurring during this process are as follows:

[0047] SiO3 2- +AlO2 - →—Si—O—Al—

[0048] Then the sol solution of step (6) and ZnO are used to solidify the graphite tailings sand.

[0049] In this embodiment, the solidification method of graphite tailings is as follows: take a certain amount of graphite tailings with a water content of less than 30% and add a sol solution of 30% to 50% of its weight, i.e., the solution of step (6), stir evenly, and then add 5% of the weight of the graphite tailings ZnO; shape the mold at room temperature, and after about 1 hour, the graphite tailings slurry begins to solidify and harden; in this process, the linear aluminosilicate oligomer molecules are 2+ Under the action of the aggregates, they grow and cross-link into a network structure, forming dense silicate aluminum zincate (SiO2-Al2O3-ZnO) gel aggregates to form strength.

[0050] In order to enable those skilled in the art to further understand the curing process and curing effect, a specific implementation case is provided below.

[0051] Example 1:

[0052] 1. Curing agent based on aluminosilicate zincate (SiO2-Al2O3-ZnO) sol system:

[0053] In this embodiment, the curing agent includes a sol solution prepared from Al2(SO4)3, KOH, 50% sodium water glass solution (n≤2.5) and ZnO;

[0054] The specific preparation method comprises the following steps:

[0055] (1) Weigh 50 g of 50% sodium water glass solution (n ≤ 2.5) and place it in a glass, ceramic, enamel, fiberglass or stainless steel container for later use;

[0056] (2) Weigh 20 g of Al2(SO4)3 into a glass, ceramic, enamel, fiberglass, or stainless steel container and dissolve it in 80 g of tap water to obtain a 20% clear Al2(SO4)3 aqueous solution;

[0057] (3) Weigh 20 g of KOH and place it in a glass, ceramic, enamel, fiberglass, or stainless steel container. Dissolve it in 80 g of tap water to obtain a 20% clear KOH aqueous solution.

[0058] (4) Weigh 5 g of ZnO powder and set aside;

[0059] (5) Take equal weights of an Al2(SO4)3 aqueous solution and a KOH aqueous solution. Slowly pour the 20% KOH aqueous solution into the 20% Al2(SO4)3 aqueous solution while stirring to obtain a clear aqueous solution containing 10% KAlO2.

[0060] (6) Take equal weights of 50% sodium water glass solution and a clear aqueous solution containing 10% KAlO2, slowly pour the clear aqueous solution containing 10% KAlO2 into the 50% sodium water glass solution while stirring, and mix well to obtain a clear sol solution.

[0061] 2. Graphite tailings sand solidification process:

[0062] Weigh 100g of graphite tailings with a water content of less than 30%, add 50g of sol solution, stir evenly, then add 5g of ZnO powder, mix evenly and pour into a mold to shape; at room temperature, demould after 1h and carefully place it in the designated place; it can be moved to another location at will after three days, and can be used after one week.

[0063] Example 2:

[0064] The difference from Example 1 is that the curing agent includes a sol solution prepared from Al2(SO4)3, NaOH, 50% sodium water glass solution (n≤2.5) and ZnO, and the remaining steps are the same as Example 1.

[0065] Example 3:

[0066] The difference from Example 1 is that the curing agent includes a sol solution prepared from Al(NO3)3, KOH, 50% sodium water glass solution (n≤2.5) and ZnO, and the remaining steps are the same as Example 1.

[0067] Example 4:

[0068] The difference from Example 1 is that the curing agent includes a sol solution prepared from AlCl3, KOH, 50% sodium water glass solution (n≤2.5) and ZnO, and the remaining steps are the same as Example 1.

[0069] Example 5:

[0070] The difference from Example 1 is that the curing agent includes a sol solution prepared from Al2(SO4)3, KOH, 40% potassium water glass solution (n≤2.5) and ZnO, and the remaining steps are the same as Example 1.

[0071] Comparative Example 1:

[0072] The difference from Example 1 is that ZnO is not added;

[0073] Comparative Example 2:

[0074] The difference from Example 1 is that CaO is used instead of ZnO;

[0075] Comparative Example 3:

[0076] The difference from Example 1 is that 30% of ordinary Portland cement-based curing material is used.

[0077] The present invention measured the curing time and the cured samples of Example 1 and the comparative example, and the results were as follows:

[0078]

[0079]

[0080] The above test results show that the strength of the product after curing of the aluminosilicate curing system is higher than that of ordinary silicate cement curing materials. The addition of ZnO or CaO can not only improve the strength of the cured product, but also greatly shorten the curing time. However, the curing time of the SiO2-Al2O3-CaO system is too short to realize the preparation and molding process; the 1-2h curing time of the SiO2-Al2O3-ZnO system is most conducive to realizing a complete preparation process; therefore, considering the curing time and the strength of the cured product, the SiO2-Al2O3-ZnO system has obvious advantages.

[0081] It should be noted that the present invention conducted strength tests on the cured products of Examples 2 to 5, and the results were basically consistent with those of Example 1, so they are not illustrated one by one.

[0082] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or removed according to actual needs to meet the requirements of different situations.

Claims

1. A curing agent based on aluminosilicate zincate sol system, characterized in that: The curing agent comprises a sol solution prepared from sodium water glass or potassium water glass, NaOH or KOH, any one of aluminum sulfate, aluminum chloride, aluminum nitrate or a mixture of two or more thereof, and ZnO.

2. The curing agent based on the aluminosilicate zincate sol system according to claim 1, characterized in that: The preparation method of the curing agent comprises the following steps: (1) Weigh sodium water glass or potassium water glass and set aside; (2) Weigh any one of aluminum sulfate, aluminum chloride, and aluminum nitrate, or a mixture of two or more thereof, and add water to form a clear solution; (3) Weigh NaOH or KOH and add water to make a clear solution; (4) Weigh ZnO and set aside; (5) Take one portion each of the solutions of step (2) and step (3); pour the solution of step (3) into the solution of step (2) while stirring; (6) Take one portion each of the solution from step (5) and step (1); pour the solution from step (5) into step (1) under stirring to generate a transparent low molecular weight sol solution; Then the sol solution of step (6) and ZnO are used to solidify the graphite tailings sand.

3. A curing agent based on aluminosilicate zincate sol system according to claim 2, characterized in that: The molar number n of the sodium water glass or potassium water glass is ≤2.

5.

4. The curing agent based on the aluminosilicate zincate sol system according to claim 2, characterized in that: In step (1), 40% to 50% of sodium water glass or 40% to 50% of potassium water glass is weighed.

5. The curing agent based on the aluminosilicate zincate sol system according to claim 2, characterized in that: In step (2), a 20% to 40% clear solution is prepared.

6. The curing agent based on the aluminosilicate zincate sol system according to claim 2, characterized in that: In step (3), a 20% to 40% clear solution is prepared.

7. The curing agent based on the aluminosilicate zincate sol system according to claim 2, characterized in that: In step (5), equal weight portions of the solutions of step (2) and step (3) are taken; and in step (6), equal weight portions of the solutions of step (5) and step (1) are taken.

8. A method for solidifying graphite tailings sand using the curing agent based on the silicate aluminum zincate sol system according to any one of claims 1 to 7, characterized in that: The specific steps are: take graphite tailings, add 30% to 50% of its weight of sol solution, stir evenly, then add 3-8% of ZnO by weight of graphite tailings and mix evenly; shape the mold at room temperature, and solidify and demold in just 1 to 2 hours.

9. The method according to claim 8, characterized in that The added amount of ZnO is 4-6% of the weight of the graphite tailings sand.

10. The method according to claim 8, characterized in that The water content of the graphite tailings sand is less than 30%.

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