Firework mould pressing barrel based on cassava flour pre-gelatinization and preparation method of firework mould pressing barrel

Abstract

The invention relates to the technical field of firework cylinders, in particular to a firework mold pressing cylinder based on cassava flour pregelatinization and a preparation method thereof, and the mold pressing cylinder is prepared from the following raw materials in parts by weight: a framework material compounded by crystal transformation method II type anhydrous gypsum and calcium carbonate stone powder, pregelatinized cassava flour, wood fibers, stearic acid and a proper amount of water. The tapioca flour is pre-gelatinized by warm water at 40-60 DEG C, and the pre-gelatinization degree is greater than or equal to 80 The crystal transformation method II type anhydrous gypsum is prepared from ardealite through a low-temperature crystal transformation method. The preparation method comprises the following steps: pre-gelatinizing the tapioca flour, pulping, mixing with other dry blends and hot water, and finally carrying out high-temperature compression molding. Through the synergistic effect of the pre-gelatinized tapioca flour and the crystal transformation method gypsum, the dry basis dosage of the tapioca flour is remarkably reduced, meanwhile, the compressive strength and the falling resistance of the mold pressing barrel are greatly improved, the multiple purposes of reducing the cost, improving the performance and absorbing industrial solid waste phosphogypsum are achieved, the product quality is stable, and the mold pressing barrel is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of fireworks tube technology, specifically to a fireworks molding tube based on cassava flour pre-gelatinization and its preparation method. Background Technology

[0002] In fireworks and firecracker production, molded cylinders are often used as supports, separators, or fixing components for explosives. These components need to have sufficient compressive strength and impact resistance, while also being lightweight, cost-effective, and manufactured using stable processes.

[0003] Existing technologies generally use calcium carbonate powder or ordinary calcined gypsum as the skeleton material and cassava flour as the main natural binder, employing a "one-step" hot pressing process, as exemplified by the fireworks and firecrackers molded mass material and its preparation method disclosed in patent CN118955078A. This process suffers from two major problems: 1. Low binder efficiency: After cassava flour is mixed with the aggregate in dry powder form, gelatinization and bonding rely on the instantaneous high temperature within the mold. This process results in uneven and insufficient gelatinization. To ensure the basic strength of the product, the dry basis content of cassava flour is typically as high as about 10%, leading to high costs. Furthermore, excessive cassava flour may introduce drawbacks such as high hygroscopicity. 2. Limitations in skeleton material performance: Traditional stone powder consumes a large amount of resources. Existing technologies attempt to use type II anhydrous gypsum, obtained by calcining industrial by-product phosphogypsum at high temperatures (600-800℃), as all or part of the skeleton material. However, the high-temperature calcination process consumes a huge amount of energy, significantly reducing its economic and environmental benefits. Secondly, the anhydrous gypsum produced in this way often suffers from incomplete crystal structure development, irregular particle morphology, and a wide particle size distribution. This results in unsatisfactory specific surface area and surface activity, making it difficult to form a uniform and dense coating and bonding interface when mixed with adhesives (such as cassava flour). To compensate for this poor interfacial bonding efficiency and ensure that the product does not crack, a relatively high amount of adhesive must still be maintained in actual formulations, usually close to 10%. This significantly reduces the cost reduction potential brought about by utilizing solid waste gypsum, limiting its contribution to overall cost reduction and efficiency improvement, and also failing to fully leverage its technological advantages as a solid waste resource product.

[0004] Therefore, how to synergistically address both adhesive activation and framework material modification to significantly reduce the amount of expensive adhesives used, while ensuring or even improving product performance, and to achieve efficient resource utilization of industrial solid waste, has become a pressing technical problem in this field. Summary of the Invention

[0005] The present invention aims to overcome the above-mentioned defects of the prior art and provide a firework molded cylinder with better overall performance, lower cost and more environmentally friendly method of preparation thereof.

[0006] In a first aspect, the present invention provides a fireworks molding cylinder based on pregelatinized cassava flour, which is made from the following raw materials in parts by weight: 820-910 parts of skeleton material, 50-70 parts of pregelatinized cassava flour, 25-40 parts of wood fiber, 3-6 parts of stearic acid, and water added in an amount of 60%-70% of the total dry material weight; wherein, the total dry material is the sum of skeleton material, pregelatinized cassava flour, wood fiber and stearic acid; the skeleton material is a compound material of anhydrous gypsum of type II crystallization method and calcium carbonate powder.

[0007] Furthermore, in the skeleton material, the amount of anhydrous gypsum of the transcrystalline type II is 300-350 parts by weight, and the amount of calcium carbonate powder is 520-560 parts by weight.

[0008] Furthermore, the anhydrous gypsum of the type II crystallization method is prepared by using phosphogypsum as raw material, adding 1%-3% of a chemical crystallization agent by mass of phosphogypsum, and calcining at 150-220℃ for 1.5-2.5 hours, with a fineness D50≤15μm.

[0009] Furthermore, the chemical crystallizing agent is potassium sulfate or sodium chloride.

[0010] Furthermore, the pregelatinized cassava flour is prepared by mixing cassava flour with warm water at 40-60℃ at a weight ratio of 1:(0.9~1.2) and stirring for 5-15 minutes, and its pregelatinization degree is not less than 80%.

[0011] Secondly, this invention provides a method for preparing a fireworks molding cylinder based on cassava flour pregelatinization, comprising the following sequential steps: S1 Pregelatinization treatment: Mix cassava flour with warm water at 40-60℃ in a certain proportion to make pregelatinized cassava flour slurry; S2 Preparation and Dry Mixing: Weigh out the anhydrous gypsum of type II crystallization method, calcium carbonate powder, wood fiber and stearic acid according to the proportion, and mix them evenly to obtain dry mix. S3 Wet mixing: Add the pregelatinized cassava flour slurry and hot water at 90-100℃ to the dry mixture and stir to form a uniform slurry; S4 Hot Press Molding: The slurry is injected into a mold preheated to 200-260℃, held under pressure of 8-15MPa for 8-12 minutes, and then heated and cured at 200-260℃ until no steam escapes from the outside of the mold; S5 Demolding: Open the mold and remove the formed molded cylinder.

[0012] Further, in step S1, the weight ratio of the cassava flour to warm water is 1:(0.9~1.2), and the stirring time is 5-15 minutes.

[0013] Furthermore, in step S2, the dry mixing time is 3-5 minutes.

[0014] Furthermore, in step S4, the preheating temperature of the mold is 220-240℃, and the holding pressure is 10-12MPa.

[0015] Compared with the prior art, the technical solution of this application has the following beneficial effects: 1. Significantly reduced adhesive usage and outstanding cost advantages: The pre-gelatinization process greatly improves the bonding efficiency of cassava flour. At the same time, the use of gypsum modified by the crystallization method and with optimized surface properties significantly reduces the ineffective adsorption of adhesives. Under the dual effect, the dry basis usage of cassava flour is greatly reduced, and the raw material cost is significantly reduced.

[0016] 2. Significantly improved overall mechanical properties of the product: Pregelatinized cassava flour slurry has good fluidity, enabling it to more evenly and fully coat and bridge aggregate particles; the crystallization process of gypsum can form a denser interfacial bond with the adhesive. The synergistic effect of these two processes increases the compressive strength of the product by 15%-22% compared to traditional "one-step" stone powder-based products, and also significantly improves its drop resistance (drop test pass rate).

[0017] 3. Significant environmental and resource benefits: One of the core framework materials, the crystallization gypsum, is derived from industrial solid waste phosphogypsum, realizing the high-value utilization of bulk solid waste, reducing dependence on natural stone powder, and conforming to the direction of green manufacturing.

[0018] 4. Stable product quality and strong process controllability: The pregelatinization process is independent and controllable, ensuring the uniformity of adhesive activity; the crystallization method of gypsum has stable properties. The combination of these two factors results in batch consistency of the final product that is far superior to that of traditional unstable processes. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0020] 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.

[0021] Example 1: A fireworks molding cylinder based on cassava flour pregelatinization, the raw materials of which are prepared in the following parts by weight: Type II anhydrous gypsum by crystallization: 320 parts Calcium carbonate powder: 540 parts Pregelatinized tapioca flour (on a dry basis): 65 parts Wood fiber: 30 parts Stearic acid: 5 parts Water: 650 parts (approximately 67% of the total dry weight) Preparation method as follows Figure 1 As shown: S1 Pregelatinization Treatment: Weigh 10kg of cassava flour, add 10kg of warm water at 50℃, and mechanically stir for 10 minutes to obtain a uniform viscous slurry with a pregelatinization degree ≥85%.

[0022] S2 Preparation and Dry Mixing: Weigh out the anhydrous gypsum of type II crystallization method, calcium carbonate powder, wood fiber and stearic acid according to the proportion, and put them into the mixer and dry mix for 4 minutes until uniform. The anhydrous gypsum of type II crystallization method is prepared by adding 2% potassium sulfate to phosphogypsum as a crystallization agent, calcining it at 180℃ for 2 hours, and grinding it to D50=12μm.

[0023] S3 Wet Mixing: Add the pregelatinized cassava flour slurry (equivalent to 65 parts on a dry basis) obtained in step S1 and hot water at 95°C to the dry mixture in step S2, and stir quickly to form a uniform slurry.

[0024] S4 Hot Press Molding: The slurry is injected into the mold cavity preheated to 230℃, the mold is closed and held under 12MPa pressure for 10 minutes. At the same time, the mold is continuously heated to keep the internal temperature at about 230℃ until no obvious water vapor escapes from the outer wall of the mold.

[0025] S5 Demolding: Open the mold, remove the formed molded cylinder, and obtain product M1 after cooling.

[0026] Example 2: A fireworks molding cylinder based on cassava flour pregelatinization, the raw materials of which are prepared in the following parts by weight: Type II anhydrous gypsum by crystallization: 300 parts Calcium carbonate powder: 560 parts Pregelatinized tapioca flour (on a dry basis): 70 parts Wood fiber: 35 parts Stearic acid: 6 parts Water: 600 parts (approximately 61% of the total dry weight) Preparation method: S1 Pregelatinization Treatment: Weigh 10kg of cassava flour, add 9kg of warm water at 55℃, stir for 12 minutes to obtain pregelatinized slurry.

[0027] S2 Preparation and Dry Mixing: Weigh each dry material according to the proportion and dry mix for 3 minutes. Type II anhydrous gypsum by crystallization method is prepared by adding 1.5% sodium chloride to phosphogypsum as a crystallization agent, calcining at 200℃ for 1.8 hours, and grinding to D50=14μm.

[0028] S3 Wet Mixing: Add the pre-gelatinized slurry (equivalent to 70 parts on a dry basis) and 98°C hot water to the dry mix and stir to form a slurry.

[0029] S4 Hot Press Molding: The slurry is injected into a mold preheated to 220°C, held under pressure of 10MPa for 12 minutes, and then heated and cured at 220°C until no steam is emitted.

[0030] S5 Demolding: Open the mold and remove product M2.

[0031] Example 3: A fireworks molding cylinder based on cassava flour pregelatinization, the raw materials of which are prepared in the following parts by weight: Type II anhydrous gypsum by crystallization: 350 parts Calcium carbonate powder: 520 parts Pregelatinized tapioca flour (on a dry basis): 60 parts Wood fiber: 40 parts Stearic acid: 4 parts Water: 650 parts (approximately 66% of the total dry weight) Preparation method: S1 Pregelatinization Treatment: Weigh 10kg of cassava flour, add 12kg of warm water at 45℃, stir for 8 minutes to obtain pregelatinized slurry.

[0032] S2 Preparation and Dry Mixing: Weigh each dry material according to the proportion and dry mix for 5 minutes. Type II anhydrous gypsum by crystallization method is prepared by adding 2.5% potassium sulfate to phosphogypsum as a crystallization agent, calcining at 160℃ for 2.2 hours, and grinding to D50=10μm.

[0033] S3 Wet Mixing: Add the pre-gelatinized slurry (equivalent to 60 parts on a dry basis) and 92°C hot water to the dry mix and stir to form a slurry.

[0034] S4 Hot Press Molding: The slurry is injected into a mold preheated to 240°C, held under pressure of 14MPa for 9 minutes, and then cured by heating at 240°C.

[0035] S5 Demolding: Open the mold and remove product M3.

[0036] Comparative Example 1: Preparation of molded cylinders using the traditional "one-step method": Raw materials: 795 parts calcium carbonate powder, 150 parts ordinary cassava flour (approximately 10.7% of dry materials), 50 parts lignocellulose, 5 parts stearic acid, and 6500 parts water.

[0037] Preparation: Mix all dry materials, add 95℃ hot water and stir, then directly pour into a 200℃ mold, pressurize at 10MPa and heat to solidify until no steam is released, then demold to obtain product D.

[0038] Performance testing and comparison: Key performance tests were conducted on the products obtained in Examples M1, M2, and M3 and Comparative Example D, and the results are shown in the table below:

[0039] Results analysis: Test data shows that the fireworks molding cylinders prepared in embodiments M1-M3 of this invention, through the synergistic effect of pre-gelatinized cassava flour and anhydrous gypsum prepared by a specific process with optimized surface structure using a crystallization method II, significantly reduce the dry basis amount of cassava flour adhesive, by more than 30% compared to traditional methods. Simultaneously, the compressive strength and drop resistance (drop pass rate) of the product are significantly improved, and production costs are significantly reduced, with process stability far superior to the traditional "one-step method." This fully demonstrates the comprehensive technical advantages of this invention in ensuring and improving product performance while achieving cost reduction, efficiency improvement, and resource utilization of industrial solid waste.

[0040] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A fireworks molding cylinder based on cassava flour pre-gelatinization, characterized in that: Made from the following parts by weight of raw materials: The mixture comprises 820-910 parts of skeleton material, 50-70 parts of pregelatinized cassava flour, 25-40 parts of lignocellulose, 3-6 parts of stearic acid, and water at a weight of 60%-70% of the total dry material. The total dry material is the sum of the skeleton material, pregelatinized cassava flour, lignocellulose, and stearic acid. The skeleton material is a compound of anhydrous gypsum of type II crystallization method and calcium carbonate powder.

2. The firework molding cylinder based on cassava flour pregelatinization according to claim 1, characterized in that: In the skeleton material, the amount of anhydrous gypsum of type II crystallization method is 300-350 parts by weight, and the amount of calcium carbonate powder is 520-560 parts by weight.

3. A fireworks molding cylinder based on cassava flour pre-gelatinization according to claim 1 or 2, characterized in that: The anhydrous gypsum of the transcrystallization method II is prepared by using phosphogypsum as raw material, adding 1%-3% of chemical transcrystallization agent by mass of phosphogypsum, and calcining at 150-220℃ for 1.5-2.5 hours, with a fineness D50≤15μm.

4. A fireworks molding cylinder based on cassava flour pregelatinization according to claim 3, characterized in that: The chemical crystallizing agent is potassium sulfate or sodium chloride.

5. A fireworks molding cylinder based on cassava flour pregelatinization according to claim 1, characterized in that: The pregelatinized cassava flour is prepared by mixing cassava flour with warm water at 40-60℃ at a weight ratio of 1:(0.9~1.2) and stirring for 5-15 minutes, with a pregelatinization degree of not less than 80%.

6. A method for preparing a firework molded cylinder based on cassava flour pregelatinization according to any one of claims 1-5, characterized in that: Includes the following steps: S1 Pregelatinization treatment: Mix cassava flour with warm water at 40-60℃ in a certain proportion to make pregelatinized cassava flour slurry; S2 Preparation and Dry Mixing: Weigh out the anhydrous gypsum of type II crystallization method, calcium carbonate powder, wood fiber and stearic acid according to the proportion, and mix them evenly to obtain dry mix. S3 Wet mixing: Add the pregelatinized cassava flour slurry and hot water at 90-100℃ to the dry mixture and stir to form a uniform slurry; S4 Hot Press Molding: The slurry is injected into a mold preheated to 200-260℃, held under pressure of 8-15MPa for 8-12 minutes, and then heated and cured at 200-260℃ until no steam escapes from the outside of the mold; S5 Demolding: Open the mold and remove the formed molded cylinder.

7. The method for preparing the fireworks molding cylinder according to claim 6, characterized in that: In step S1, the weight ratio of cassava flour to warm water is 1:(0.9~1.2), and the stirring time is 5-15 minutes.

8. The method for preparing the fireworks molding cylinder according to claim 6, characterized in that: In step S2, the dry mixing time is 3-5 minutes.

9. The method for preparing the fireworks molding cylinder according to claim 6, characterized in that: In step S4, the preheating temperature of the mold is 220-240℃, and the holding pressure is 10-12MPa.

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