Crushing method of waste solid composite propellant

Abstract

The invention belongs to the technical field of solid composite propellant recovery, and particularly relates to a crushing method of a waste solid composite propellant. The preparation method comprises the following steps: firstly, generating a composite precipitate of ferric hydroxide and aluminum hydroxide by using ferric trichloride hexahydrate and aluminum trichloride hexahydrate, filtering and washing the precipitate, mixing and ball-milling with carbon nanotubes and ethanol, and finally calcining to obtain the nano composite grinding aid. After the nano composite grinding aid is prepared into suspension liquid, the suspension liquid and the waste solid composite propellant are jointly crushed and screened, and crushed solid composite propellant particles can be obtained through separation. The prepared nano composite grinding aid can improve the performance of the propellant, the crushing method is particularly suitable for combustion recovery of the waste solid composite propellant, and in the combustion recovery process, the recovery heat value and the energy utilization rate of the propellant can be remarkably increased by enhancing the combustion efficiency and energy release.

Description

Technical Field

[0001] The invention belongs to the technical field of solid composite propellant recovery, and in particular relates to a method for crushing waste solid composite propellant. Background Art

[0002] Composite propellant is a high-energy-density fuel widely used in rockets, missiles and other weapons and equipment. However, during the production and storage process, due to the influence of time and storage conditions, solid composite propellants may experience surface hardening, interface shedding, density reduction, loss of energetic components, etc. Therefore, generally after 5 to 10 years, the aged composite solid composite propellant will enter the scrap period.

[0003] Waste solid composite propellant contains ingredients such as oxidizer, fuel, adhesive, etc., which cause a certain degree of damage to the environment and pose certain safety hazards. Therefore, the recovery and resource utilization of the effective components of the composite propellant are of great practical significance. The first step in recycling composite propellants is to crush the waste solid composite propellant. Smaller particle size can be more easily sorted and recycled, and it is also easier to carry out harmless treatment, thereby reducing pollution to the environment. The inventor's previous patent CN118684252B discloses a method for recycling waste solid composite propellant, which makes the composite propellant and aluminum-containing powder into a slurry fluid and then burns it for recovery. The precondition of this method also requires the composite propellant to be crushed.

[0004] Waste solid composite propellants are generally crushed by wet method. When using wet method, the particles of solid composite propellants are particularly easy to precipitate, which is not conducive to feeding. In addition, solid composite propellants are elastic, and pressure will cause their shape to change, allowing them to be squeezed out through a relatively small aperture. However, after extrusion, the material rebounds to a larger size, resulting in poor crushing effect.

[0005] Grinding aids can improve the crushing effect of waste solid composite propellants, but there are few reports on grinding aids for waste solid composite propellants. Existing grinding aids for solid waste are difficult to use in waste solid composite propellants. For example, patent EP123456789A1 discloses an iron-aluminum complex as a grinding aid in various industrial products (including cement and mineral grinding), but the crushing effect of this iron-aluminum complex in elastic materials is not ideal.

[0006] Therefore, finding a method that can effectively crush waste solid composite propellants is a technical problem to be solved. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a method for crushing waste solid composite propellant.

[0008] The technical means adopted by the present invention are as follows: A method for crushing waste solid composite propellant comprises the following steps: S1. mixing ferric chloride hexahydrate, aluminum chloride hexahydrate and water in a mass ratio of (10-25): (5-15): (60-85), adding an appropriate amount of aqueous ammonia, adjusting the pH value to 8-10, filtering and washing the resulting precipitate, mixing it with carbon nanotubes and ethanol in a mass ratio of (5-10): (1-3): (22-55), putting it into a ball mill for ball milling, and then drying and calcining to obtain a nanocomposite grinding aid; S2. uniformly mixing the nanocomposite grinding aid with water to form a suspension having a density of 1.3 to 1.9 g / cm³, and adding the suspension and the solid composite propellant in a mass ratio of (25 to 50): (10 to 20) into a pulverizing device for pulverization; S3. The material obtained after the pulverization is sieved with a screen to separate and obtain pulverized solid composite propellant particles.

[0009] Preferably, the solid composite propellant is a hydroxyl-terminated composite propellant.

[0010] Preferably, in step S1, the ball milling medium is tungsten carbide balls, the ball milling speed is 250 rpm, the ball-to-material ratio is 50:1, and the ball milling time is 10 h.

[0011] Preferably, in the step S1, the calcination is carried out under an inert gas atmosphere at 600° C. for 2 h.

[0012] Preferably, in step S2, the pulverizing device is a shearing pulverizing pump, the rotation speed of the pulverizing pump rotor is 2000-2500 r / min, the single pulverizing time is 5 min, the single feed amount is 10 kg, and the pulverizing is performed 3-5 times in total.

[0013] Preferably, in step S3, the aperture of the sieve is 0.2-1 mm.

[0014] Preferably, in the step S3, the remaining material after screening is subjected to magnetic separation to separate magnetite powder, and then centrifuged to separate nano-alumina powder, and the magnetite powder and nano-alumina powder are reused as nano-composite grinding aids.

[0015] The beneficial effects of the present invention are as follows: 1) The present invention provides a grinding aid suitable for waste solid composite propellant. Ferric chloride hexahydrate and aluminum chloride hexahydrate are synthesized into a magnetite and alumina composite material by a co-precipitation method, and then the composite material is mixed with carbon nanotubes and ethanol, and then mechanically ball-milled, dried, and calcined to obtain a nano-composite grinding aid. The nano-composite grinding aid is mixed with water in a certain proportion to form a suspension, and then mixed with the solid propellant in proportion, so that the concentration of the material can be adjusted more flexibly, and the particles of the propellant can be in a suspended state, so that it can be transported to the crushing equipment by pumping, and the precipitation problem can be prevented during the feeding process, thereby realizing a more uniform crushing process and achieving a better crushing effect.

[0016] 2) The nanocomposite grinding aid prepared by the present invention has a relatively large hardness, and can assist in promoting the grinding process of the propellant particles during the pulverization process, so as to make the discharging process smoother, improve the grinding efficiency, and reduce energy consumption. The nanocomposite grinding aid also has good dispersibility, can reduce the agglomeration of solid composite propellant particles, help improve the performance of the propellant, and can improve the combustion efficiency during combustion recovery.

[0017] 3) The crushed waste solid composite propellant of the present invention is particularly suitable for combustion recovery. During the combustion process, the nanocomposite grinding aid remaining in the separation process can undergo redox reaction and catalytic reaction with the solid composite propellant to increase the combustion temperature and heat transfer efficiency. By enhancing the combustion efficiency and energy release, the recovery calorific value and energy utilization rate of the propellant can be significantly improved.

[0018] 4) The properties of nano-composite grinding aids and solid composite propellants are very different. The magnetite powder and nano-alumina powder in the crushed materials can be recovered and recycled through screening, magnetic separation, and centrifugation, which reduces the cost of crushing waste solid composite propellants, improves economic benefits, and helps build a resource-saving and environmentally friendly society. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 These are the TGA experimental test results of the solid composite propellant particles obtained in Examples 1-3 and Comparative Example 4. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is described in more detail below in conjunction with the embodiments.

[0021] Unless otherwise specified, various materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0022] Preparation of nano-composite grinding aid: Iron trichloride hexahydrate, aluminum trichloride hexahydrate and water are mixed in a mass ratio of 15:10:75, and then an appropriate amount of ammonia water is added to adjust the pH value to 9 to produce a composite precipitate of iron hydroxide and aluminum hydroxide. The filtered precipitate is washed, mixed with carbon nanotubes and ethanol in a mass ratio of 10:1:35 and put into a ball mill for ball milling. The ball milling medium is tungsten carbide balls, the speed is set to 250 rpm, the ball-to-material ratio is 50:1, the ball milling time is 10 hours, the ball-milled material is dried at 80°C for 4 hours, and the dried material is calcined at 600°C in an argon atmosphere for 2 hours to obtain a nano-composite grinding aid.

[0023] A certain amount of nanocomposite grinding aid and water were weighed and placed in a mixing tank. The stirrer was rotated at 700 r / min and stirred evenly for 10 min to obtain a suspension. The ratio of magnetite powder to water was adjusted according to the above method to obtain three groups of suspensions of different densities in Examples 1-3. The specific ratios are shown in Table 1 below.

[0024] Table 1 Suspension formula and density ; The suspension prepared in Example 1-3 and the waste solid composite propellant were added to a shearing type crushing pump at a mass ratio of 35:15 for crushing. The rotor speed of the shearing type crushing pump was 2300 r / min, the single crushing time was 5 min, the single feed amount was 10 kg, and the crushing times were 3 times. The crushed material was preliminarily screened through a sieve with an aperture of 0.2 mm to separate the solid composite propellant particles. The material smaller than 0.2 mm was recovered by a magnetic separator to recover the magnetite powder, and then further separated by a centrifuge to obtain nano alumina powder. The speed of the centrifuge was set to 3500 rpm, and the centrifugation time was 15 min.

[0025] In this embodiment, the ratio of the components of the waste solid composite propellant is: 35.71wt% of terminal hydroxyl polybutadiene, 23.21wt% of ammonium perchlorate, 5.36wt% of cyclotrimethylene trinitramine, 3.57wt% of toluene diisocyanate, 10.71wt% of dioctyl sebacate, and 21.43wt% of aluminum.

[0026] In Comparative Example 1, while the components of the waste solid composite propellant remain unchanged, magnetite powder is used as a grinding aid, the true density of the magnetite powder is 4.7 g / cm³, the magnetic content is 98%, and the density of the prepared suspension is 1.6 g / cm³.

[0027] In Comparative Example 2, while the components of the waste solid composite propellant remain unchanged, nano-alumina is used as the grinding aid, the true density of nano-alumina is 4.0 g / cm³, and the density of the prepared suspension is 1.6 g / cm³.

[0028] In Comparative Example 3, when the components of the waste solid composite propellant remain unchanged, calcium carbonate is used as the grinding aid, and the purity of calcium carbonate needs to be above 98%. The density of the prepared suspension is 1.6 g / cm³.

[0029] In Comparative Example 4, no grinding aid was used, and the waste solid composite propellant was directly added into a shearing type pulverizing pump for pulverization. The speed of the rotor of the shearing type pulverizing pump was 2300 r / min, and the pulverization times were 10 times.

[0030] The waste solid composite propellant particles obtained in Examples 1-3 and Comparative Examples 1-4 were sieved by a sieving method, and the pulverization fineness was shown in Table 2.

[0031] Table 2 Particle size composition of crushed waste solid composite propellant ;

[0032] It can be seen that after the materials of Examples 1-3 were crushed three times, the particle size greater than 1 mm was less than 12.17%, and more material particles were distributed in a finer particle size range (<0.2mm and 0.2~0.5mm). After the materials of Comparative Examples 1, 2 and 3 were crushed five times, the particle size greater than 1 mm was more than 30.73%, and after Comparative Example 4 was crushed 10 times, the particle size greater than 1 mm was 46.74%, and the particle size distribution was smaller than that of other embodiments. The experiment shows that the nano-composite grinding aid prepared by the present invention can effectively assist in promoting the grinding process of propellant particles during the crushing process, improve the grinding efficiency, reduce the cost of crushing waste solid composite propellants, and improve economic benefits.

[0033] The crushed solid composite propellant in Example 1-3 was subjected to LC-MS test, and the contents of each component in the crushed solid composite propellant particles are shown in Table 3 below.

[0034] Table 3 Analysis of the content of the solid composite propellant after crushing of Example 1-3 ;

[0035] It can be seen that after recovery, magnetite, alumina and carbon nanotubes appeared in Examples 1-3, indicating that nanocomposite grinding aids remained in the crushed materials after magnetic separation and centrifugal recovery, and the greater the density of the suspension used, the higher the residual ratio.

[0036] In order to determine the effect of residual nanocomposite grinding aid on the combustion performance of solid composite propellant, TGA test was performed on the solid composite propellant particles obtained in Examples 1-3 and Comparative Example 4. The test results are shown in Figure 1. It can be seen that in the temperature range of 200-300°C, the decomposition rates of all embodiments are basically the same. In the temperature range of 300-600°C, the decomposition rate of Example 3 decreases the fastest, the decomposition rates of Examples 1 and 2 decrease faster, and the decrease rate of Comparative Example 4 is relatively slow. In the temperature range of 600-800°C, the burnout rates of the solid composite propellants in Examples 1-3 are higher than that in Comparative Example 4, indicating that the nanocomposite grinding aid accelerates the decomposition reaction of the solid composite propellant.

[0037] The high calorific value of Examples 1-3 and Comparative Examples 1-4 was tested using oxygen bomb calorimetry. The test results are shown in Table 4 below.

[0038] Table 4 High calorific value of solid composite propellant after crushing ;

[0039] The t-test was used to compare the mean calorific value of the embodiment group and the comparative example group. p The value is 0.002. The calorific value of the solid composite propellant crushed according to the method is generally higher than that of the comparative example, and there is a significant difference in the calorific value. The crushing method of the present invention can effectively increase the combustion calorific value of the solid composite propellant and improve the energy utilization rate.

[0040] The above implementation modes are only used to illustrate the technical solutions of the present invention, but not to limit the present invention. Although the present invention has been described in detail with reference to the above implementation modes, those skilled in the art should understand that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for crushing waste solid composite propellant, It is characterized in that The following steps are involved: S1. mixing ferric chloride hexahydrate, aluminum chloride hexahydrate and water in a mass ratio of (10-25): (5-15): (60-85), adding an appropriate amount of ammonia water, adjusting the pH value to 8-10, filtering and washing the resulting precipitate, mixing it with carbon nanotubes and ethanol in a mass ratio of (5-10): (1-3): (22-55), putting it into a ball mill for ball milling, and then drying and calcining to obtain a nanocomposite grinding aid; S2. uniformly mixing the nanocomposite grinding aid with water to form a suspension having a density of 1.3 to 1.9 g / cm³, and adding the suspension and the solid composite propellant in a mass ratio of (25 to 50): (10 to 20) into a pulverizing device for pulverization; S3. The material obtained after the pulverization is sieved with a screen to separate and obtain pulverized solid composite propellant particles.

2. A method for crushing waste solid composite propellants according to claim 1, It is characterized in that The solid composite propellant is a hydroxyl-terminated composite propellant.

3. A method for crushing waste solid composite propellant according to claim 1, It is characterized in that In the step S1, the ball milling medium is tungsten carbide balls, the ball milling speed is 250 rpm, the ball-to-material ratio is 50:1, and the ball milling time is 10 h.

4. A method for crushing waste solid composite propellant according to claim 1, It is characterized in that In the step S1, the calcination is carried out at 600° C. for 2 h in an inert gas atmosphere.

5. A method for crushing waste solid composite propellant according to claim 1, It is characterized in that In step S2, the pulverizing device is a shearing pulverizing pump, the rotation speed of the pulverizing pump rotor is 2000-2500 r / min, the single pulverizing time is 5 min, the single feed amount is 10 kg, and the pulverizing is performed 3-5 times in total.

6. A method for crushing waste solid composite propellant according to claim 1, It is characterized in that In step S3, the aperture of the sieve is 0.2-1 mm.

7. A method for crushing waste solid composite propellant according to claim 1, It is characterized in that In the step S3, the remaining materials after screening are subjected to magnetic separation to separate magnetite powder, and then centrifuged to separate nano-alumina powder. The magnetite powder and nano-alumina powder are reused as nano-composite grinding aids.

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