Core-shell aluminized thermite, preparation method and application in biomass blasting device

Abstract

The application belongs to the technical field of nanocomposites, and particularly relates to a core-shell type thermite, a preparation method and application in a biomass blasting device. The preparation method comprises the following steps: S1, adding fly ash into a hydrochloric acid solution to dissolve the fly ash, then filtering to obtain a filtrate, adding a sodium hydroxide solution into the filtrate, then performing stirring, filtering and drying treatment to obtain a precipitate, calcining the precipitate to obtain iron oxide particles for standby; S2, adding aluminum powder and boron powder into an organic solvent to perform ultrasonic mixing, then performing heating and stirring to volatilize the organic solvent to obtain an aluminum-boron compound, and drying for standby; S3, adding the iron oxide particles, the aluminum-boron compound and an adhesive into an acetone solution to mix uniformly to obtain a mixture, performing stirring and ultrasonic treatment on the mixture to obtain a suspension; adding a polyvinyl alcohol emulsifier into deionized water and performing heating and stirring to obtain an emulsion; S4, in a high-speed dispersion homogenizer, adding the suspension dropwise into the emulsion to wrap the suspension in the emulsion to obtain an oil-in-water emulsion, and performing evaporation, filtering, washing and drying treatment on the oil-in-water emulsion to obtain the core-shell type nano thermite.

Description

Technical Field

[0001] This invention belongs to the field of nanocomposite materials technology, specifically relating to a core-shell thermite, its preparation method, and its application in biomass blasting devices. Background Technology

[0002] As is well known, biomass is one of the most important energy sources for human survival, ranking fourth after coal, oil, and natural gas, and is considered one of the most promising renewable energy sources of the 21st century. Furthermore, my country is an agricultural country rich in biomass resources, with annual usable biomass energy equivalent to approximately 460 million tons of standard coal, but actual utilization is less than 10% of the total. The large amount of biomass not being effectively utilized not only leads to resource waste but also causes environmental pollution. Activating biomass for applications such as engineering blasting is an important way to realize the energy utilization of biomass. The invention of a dedicated activation device for biomass blasting is of great significance in solving the increasingly serious energy problem. However, biomass has low sensitivity and requires a large amount of external energy to activate. Utilizing the advantages of metastable intermolecular complexes, such as ultra-high reaction rate, high volumetric energy density, and micro / nano-scale critical reaction propagation size, the invention of a thermal activation device based on nano-aluminothermic agents is of great significance.

[0003] Current research on nano-aluminothermic agents is extensive both domestically and internationally, primarily focusing on preparation methods. For example, Chinese patent 2022106277934 describes a method of preparing a suspension from aluminum particles, a copper source, and a carbon source in a specific ratio, followed by spray drying and calcination to obtain an aluminothermic agent containing a carbon framework. This method allows for sufficient contact between the aluminum particles and the carbon-framework copper oxide, reducing the electrostatic insensitivity without weakening the Al / CuO reactivity of the nano-aluminothermic agent. Another example is Chinese patent 2021110681841, which uses direct ink writing to safely and controllably mix hollow carbon nanospheres with Al / Fe2O3 nano-aluminothermic solid particles. This method safely and easily achieves the preparation of novel aluminothermic agent structures with controllable size and shape, providing new insights for the design of energetic materials. Patent 2021101742282 describes a method using Cu(NO3)2·H2O and urea to obtain a copper oxide precursor. The resulting porous copper oxide is then physically mixed with nano-aluminum powder to obtain an energetic nAl / pCuO composite material. Finally, nAl / pCuO@P4VP nano-aluminothermic agents are obtained through a P4VP self-assembly method. The prepared nano-aluminothermic agents exhibit excellent efficacy, with significantly reduced agglomeration between components, resulting in a substantial increase in the contact area between the nano-aluminum powder and copper oxide. This contributes to the energy release and improved reactivity of the nano-aluminothermic agents.

[0004] The rapid development of science and technology has broadened the application scope of blasting technology, expanding its application areas to include rock mass decomposition and public building demolition. However, the shortcomings of some existing traditional blasting devices, such as environmental safety, energy utilization, and environmental protection, are becoming increasingly apparent. Therefore, the research and application of a dedicated thermal initiation device based on fracturing agents has gradually become a focus of research in this field, aiming to fundamentally improve the safety and efficiency of blasting technology to meet the needs of social development. For example, Chinese Patent 2021112638121 discloses a non-explosive electronic detonator system, providing an improvement in the hardware structure of a non-explosive electronic detonator system, including a non-explosive detonator and a three-way connector. This system can increase the ignition probability of the detonator and has high flexibility. Another example is Chinese Patent 2020102508076, which uses a single layer of nitrocellulose ignition to achieve a stable combustion-to-detonation reaction. This process, while controlling the amount of nitrocellulose used, helps to increase the ignition probability of the detonator. This invention effectively solves the problem of wastewater treatment difficulties faced in the production of traditional detonators, while also helping to reduce production costs and minimize health hazards to workers during the production process. Furthermore, this innovative technology can also address the problems of insufficient detonation capability and low inherent safety in traditional non-detonating detonators. Chinese Patent 2019108462209 discloses a permissible electronic detonator for coal mines, in which the bottom charge is a high explosive with added flame suppressant, effectively preventing gas ignition. It also discloses the detonation technology of this permissible electronic detonator for coal mines, which, through careful design of the electronic detonator chip counter, ensures that the total delay time does not exceed 130 milliseconds, avoiding the danger of explosions caused by gas and coal dust.

[0005] In summary, current patents in the research of excitation devices mainly focus on improving the structure of detonator systems and improving the types or formulations of pyrotechnic agents. However, there are few inventions related to dedicated non-detonating detonators, with most being permitted electronic detonators for coal mines. Meanwhile, research on nanocomposite materials also focuses on innovation in preparation methods, with most being two-dimensional energetic materials. Existing preparation methods and technologies are insufficient to meet the needs of current societal development. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the objective of this invention can be achieved through the following technical solutions:

[0007] This invention is based on the high heat release from the aluminothermic reaction. Utilizing the advantages of metastable intermolecular complexes, such as ultra-high reaction rates, high volumetric energy density, and micro / nano-scale critical reaction propagation dimensions, and employing existing thermal analysis techniques, a novel nano-aluminothermic agent is developed. The useful components of this aluminothermic agent are extracted from fly ash and used as its main component. The prepared nano-aluminothermic agent is then applied as an ignition propellant in a dedicated activation device for biomass blasting.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for preparing a core-shell nano-aluminothermic agent, the method comprising the following steps:

[0010] S1. Add fly ash to hydrochloric acid solution to dissolve fly ash, then filter to obtain filtrate, add sodium hydroxide solution to filtrate, then stir, filter, and dry to obtain precipitate, and calcine the precipitate to obtain iron oxide particles for later use.

[0011] S2. Add aluminum powder and boron powder to an organic solvent and mix ultrasonically. Then, while heating and stirring, the organic solvent is evaporated to obtain an aluminum-boron composite. Dry it for later use.

[0012] S3. Add iron oxide particles, aluminum boron composite and binder to acetone solution and mix evenly to obtain a mixture. Stir and sonicate the mixture to obtain a suspension. Add polyvinyl alcohol emulsifier to deionized water and heat and stir to obtain an emulsion.

[0013] S4. In a high-speed dispersion homogenizer, the suspension is added dropwise to the emulsion, so that the suspension is encapsulated in the emulsion to obtain an oil-in-water emulsion. The oil-in-water emulsion is then evaporated, filtered, washed, and dried to obtain a core-shell nano-aluminothermic agent.

[0014] Furthermore, in step S1, the ratio of fly ash to hydrochloric acid solution is 1:25, and a certain amount of sodium hydroxide is slowly added to the ferric chloride solution until a reddish-brown precipitate is formed in the solution.

[0015] Furthermore, in step S1, the calcination temperature is 550–600℃ and the calcination time is 1–1.5 h.

[0016] Furthermore, in step S2, the mass ratio of aluminum powder to boron powder is 1:2.

[0017] Further, the adhesive mentioned in step S3 is one of dextrin, phenolic resin and carboxymethyl cellulose, and the mass ratio of the iron oxide particles, aluminum boron composite and adhesive is (60-65):(5-10):(30-40).

[0018] Furthermore, the content of polyvinyl alcohol emulsifier in the emulsion described in step S3 is 0.5 wt%.

[0019] A core-shell nano-aluminothermic agent is prepared by the preparation method described above.

[0020] The aforementioned core-shell nano-aluminothermic agent is used as an ignition propellant in a dedicated ignition device for biomass blasting.

[0021] An ignition device specifically designed for biomass blasting includes a charge casing, lead wires, an electronic control module, an ignition head, a reinforcing cap, and a main charge. The lead wires, electronic control module, ignition head, reinforcing cap, and main charge are all enclosed within the charge casing. The lead wires are connected to the electronic control module, which is connected to the ignition head. The reinforcing cap is adjacent to the ignition head, and the main charge is connected to the reinforcing cap. A core-shell nano-aluminothermic agent is installed at the ignition head as the ignition charge.

[0022] The beneficial effects of this invention are as follows: This invention is based on the chemical basis of the high heat released by the aluminothermic reaction. Combined with the excellent ignition performance and combustion characteristics of the obtained nano-aluminothermic agent, it can replace the initiating explosive component in digital detonators, thereby realizing the transformation of digital detonators without initiating explosives. At the same time, the "coal-based solid waste" technology is introduced to make full use of fly ash, a waste resource, to achieve the renewable utilization of resources. This not only helps to achieve sustainable development and promote energy conservation and emission reduction, but also makes an important contribution to saving a large amount of natural resources and reducing production costs. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0024] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0025] Figure 1 The structural model diagrams are shown for the high-energy nano-aluminothermic microspheres in Examples 1-6 of this invention.

[0026] Figure 2 The diagram shows the structure of the digital electronic detonator in Embodiments 1-6 of the present invention. In the diagram: 1. Lead wire; 2. Electronic control module; 3. Ignition head; 4. Reinforcing cap; 5. Main charge; 6. Charge shell. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] Preparation of core-shell nano-aluminothermic agents

[0030] S1. Add fly ash to hydrochloric acid solution at a material-to-liquid ratio of 1:25 to dissolve the fly ash, then filter to obtain filtrate. Add sodium hydroxide solution to the filtrate, then stir, filter, and dry to obtain precipitate. Calcine the precipitate to obtain iron oxide particles for later use.

[0031] S2. Add 1.0g of aluminum powder and 2.0g of boron powder to an organic solvent and mix them ultrasonically to coat the mixture. Then, while heating and stirring, the organic solvent is evaporated to obtain an aluminum-boron composite. Dry the composite for later use.

[0032] S3. Add 1.3g of iron oxide particles, 0.6g of aluminum boron composite and 0.1g of binder to 10ml of acetone solution and mix evenly to obtain a mixture. Stir and sonicate the mixture to obtain a suspension. Add 0.1g of polyvinyl alcohol emulsifier to 20ml of deionized water and heat and stir to obtain an emulsion.

[0033] S4. In a high-speed dispersion homogenizer, the suspension is added dropwise to the emulsion, so that the suspension is encapsulated in the emulsion to obtain an oil-in-water emulsion. The oil-in-water emulsion is then evaporated, filtered, washed, and dried to obtain a core-shell nano-aluminothermic agent.

[0034] The prepared core-shell nano-aluminothermic agent is used as an ignition propellant in a biomass blasting-specific activation device. The biomass blasting-specific activation device includes a charge shell 6, lead wires 1, an electronic control module 2, an ignition head 3, a reinforcing cap 4, and a main charge 5. The lead wires 1, electronic control module 2, ignition head 3, reinforcing cap 4, and main charge 5 are all enclosed within the charge shell 6. The lead wires 1 are connected to the electronic control module 2, the electronic control module 2 is connected to the ignition head 3, the reinforcing cap 4 is adjacent to the ignition head 3, and the main charge 5 is connected to the reinforcing cap 4. The core-shell nano-aluminothermic agent... The thermite is installed as the ignition charge at the ignition head 3; then the prepared biomass crushing agent (whose components are oxidizer (nitrates such as potassium nitrate or metal oxides such as copper oxide), combustible metal (aluminum powder, magnesium powder, etc.), and waste biomass powder (peanut shell powder, wheat straw powder, etc.)) is loaded into the biomass blasting-specific ignition device as the main charge 5. The ignition device is detonated by the detonator to generate a high temperature and high heat state, thereby giving the biomass crushing agent the high temperature ignition conditions to be ignited. Finally, the ignition state of the biomass crushing agent (i.e., the biomass crushing agent has been ignited and burned) is observed.

[0035] Example 2

[0036] Preparation of core-shell nano-aluminothermic agents

[0037] S1. Add fly ash to hydrochloric acid solution at a material-to-liquid ratio of 1:25 to dissolve the fly ash, then filter to obtain filtrate. Add sodium hydroxide solution to the filtrate, then stir, filter, and dry to obtain precipitate. Calcine the precipitate to obtain iron oxide particles for later use.

[0038] S2. Add 1.0g of aluminum powder and 2.0g of boron powder to an organic solvent and mix them ultrasonically to coat the mixture. Then, while heating and stirring, the organic solvent is evaporated to obtain an aluminum-boron composite. Dry the composite for later use.

[0039] S3. Add 1.2g of iron oxide particles, 0.6g of aluminum boron composite and 0.2g of binder to 10ml of acetone solution and mix evenly to obtain a mixture. Stir and sonicate the mixture to obtain a suspension. Add 0.1g of polyvinyl alcohol emulsifier to 20ml of deionized water and heat and stir to obtain an emulsion.

[0040] S4. In a high-speed dispersion homogenizer, the suspension is added dropwise to the emulsion, so that the suspension is encapsulated in the emulsion to obtain an oil-in-water emulsion. The oil-in-water emulsion is then evaporated, filtered, washed, and dried to obtain a core-shell nano-aluminothermic agent.

[0041] The prepared core-shell nano-aluminothermic agent is used as an ignition propellant in a biomass blasting-specific activation device. The biomass blasting-specific activation device includes a charge shell 6, lead wires 1, an electronic control module 2, an ignition head 3, a reinforcing cap 4, and a main charge 5. The lead wires 1, electronic control module 2, ignition head 3, reinforcing cap 4, and main charge 5 are all enclosed inside the charge shell 6. The lead wires 1 are connected to the electronic control module 2, and the electronic control module 2 is connected to the ignition head 3. The reinforcing cap 4 is located close to the ignition head 3, and the main charge 5 is connected to the reinforcing cap 4; the core-shell nano-aluminothermic agent is installed at the ignition head 3 as the ignition agent; then the prepared biomass shredder is loaded into the biomass blasting-specific ignition device as the main charge 5, and the biomass blasting-specific ignition device is detonated by the detonator to generate a high temperature and high heat state, thereby enabling the biomass shredder to have the high temperature ignition conditions to be detonated, and finally the ignition state of the biomass shredder (i.e., the biomass shredder has been ignited and burned) is observed.

[0042] Comparative Example 1

[0043] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, iron oxide particles, aluminum-boron composite and binder are directly dry-mixed in step 3 to prepare nano-aluminothermic agent, and the prepared nano-aluminothermic agent is used as ignition explosive in a biomass blasting-specific ignition device; then the prepared biomass fragmentation agent is loaded into the biomass blasting-specific ignition device as the main charge 5, and the biomass blasting-specific ignition device is detonated with a detonator. Finally, the ignition state of the biomass fragmentation agent is observed (i.e., the biomass fragmentation agent is not ignited and burned).

[0044] Comparative Example 2

[0045] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 lacks step S2, and step S3 is as follows: S3, iron oxide particles, aluminum powder and binder are added to acetone solution and mixed evenly to obtain a mixture. The mixture is stirred and ultrasonically treated to obtain a suspension. Polyvinyl alcohol emulsifier is added to deionized water and heated and stirred to obtain an emulsion. The other parts are the same as in Example 1. The prepared nano-aluminothermic agent is used as an ignition charge in a biomass blasting-specific ignition device. Then, the prepared biomass fragmentation agent is used as the main charge 5 and loaded into the biomass blasting-specific ignition device. The biomass blasting-specific ignition device is detonated with a detonator. Finally, the ignition state of the biomass fragmentation agent is observed (i.e., the biomass fragmentation agent is not ignited and burned).

[0046] Comparative Example 3

[0047] The difference between Comparative Example 3 and Example 1 is that Comparative Example 2 lacks step S2, and step S3 is as follows: S3, iron oxide particles, boron powder and binder are added to acetone solution and mixed evenly to obtain a mixture. The mixture is stirred and ultrasonically treated to obtain a suspension. Polyvinyl alcohol emulsifier is added to deionized water and heated and stirred to obtain an emulsion. The other parts are the same as in Example 1. The prepared nano-aluminothermic agent is used as an ignition charge in a biomass blasting-specific ignition device. Then, the prepared biomass fragmentation agent is used as the main charge 5 and loaded into the biomass blasting-specific ignition device. The biomass blasting-specific ignition device is detonated with a detonator. Finally, the ignition state of the biomass fragmentation agent (i.e., the biomass fragmentation agent is not ignited and burned) is observed.

[0048] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for preparing a core-shell nano-aluminothermic agent, characterized in that, The preparation method includes the following steps: S1. Add fly ash to hydrochloric acid solution to dissolve fly ash, then filter to obtain filtrate, add sodium hydroxide solution to filtrate, then stir, filter, and dry to obtain precipitate, and calcine the precipitate to obtain iron oxide particles for later use. S2. Add aluminum powder and boron powder to an organic solvent and mix ultrasonically. Then, while heating and stirring, the organic solvent is evaporated to obtain an aluminum-boron composite. Dry it for later use. S3. Add iron oxide particles, aluminum boron composite and binder to acetone solution and mix evenly to obtain a mixture. Stir the mixture and sonicate it to obtain a suspension. Polyvinyl alcohol emulsifier is added to deionized water and heated and stirred to obtain an emulsion; S4. In a high-speed dispersion homogenizer, the suspension is added dropwise to the emulsion, so that the suspension is encapsulated in the emulsion to obtain an oil-in-water emulsion. The oil-in-water emulsion is then evaporated, filtered, washed, and dried to obtain a core-shell nano-aluminothermic agent.

2. The method for preparing a core-shell nano-aluminothermic agent according to claim 1, characterized in that, In step S1, the ratio of fly ash to hydrochloric acid solution is 1:

25. Then, a certain amount of sodium hydroxide is slowly added to the ferric chloride solution until a reddish-brown precipitate is formed in the solution.

3. The method for preparing a core-shell nano-aluminothermic agent according to claim 1, characterized in that, In step S1, the calcination temperature is 550–600℃ and the calcination time is 1–1.5 h.

4. The method for preparing a core-shell nano-aluminothermic agent according to claim 1, characterized in that, In step S2, the mass ratio of aluminum powder to boron powder is 1:

2.

5. The method for preparing a core-shell nano-aluminothermic agent according to claim 1, characterized in that, The adhesive mentioned in step S3 is one of dextrin, phenolic resin and carboxymethyl cellulose, and the mass ratio of the iron oxide particles, aluminum boron composite and adhesive is (60-65):(5-10):(30-40).

6. The method for preparing a core-shell nano-aluminothermic agent according to claim 1, characterized in that, The content of polyvinyl alcohol emulsifier in the emulsion described in step S3 is 0.5 wt%.

7. A core-shell nano-aluminothermic agent is prepared by any one of the preparation methods described in claims 1-6.

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