High-density expanded ammonium nitrate explosive and method for preparing the same

Abstract

The present application relates to the technical field of explosives, in particular to a high-density expanded ammonium nitrate explosive and a preparation method thereof. The high-density expanded ammonium nitrate explosive comprises the following raw materials in parts by weight: 78-83.2 parts of ammonium nitrate, 4-4.5 parts of a composite oil phase, 4-5 parts of wood powder, 9-14 parts of porous granular ammonium nitrate, and 0.2-0.3 parts of a metal salt. The expanded ammonium nitrate explosive improves the explosive density through two-step improvement according to the oxygen balance principle, which is the basic principle of industrial explosive formula design: 1. Reducing the amount of ammonium nitrate and adding porous granular ammonium nitrate, which has the characteristic of greater bulk density, to improve the bulk density of the explosive; 2. Using the salt modification and crystallization control characteristics of the water phase additive to improve the density of the explosive. The water phase additive has the functions of filling pores and improving the crystalline structure of ammonium nitrate. Through formula design, adding an appropriate amount of water phase additive can improve the density of the expanded ammonium nitrate explosive.

Description

Technical Field

[0001] This invention relates to the field of explosives technology, specifically to a high-density expanded ammonium nitrate explosive and its preparation method. Background Technology

[0002] Traditional expanded ammonium nitrate explosives, as shown in Chinese invention patent publication CN106316722A, are prepared by using a vertical expansion crystallization mechanism to obtain expanded ammonium nitrate, which is then mixed with a composite oil phase and wood flour in a continuous mixing system. Finally, the mixed explosive is loaded and packaged to obtain the expanded ammonium nitrate explosive. However, traditional expanded ammonium nitrate explosives have the following disadvantages: 1) Traditional expanded ammonium nitrate explosives typically have a low bulk density, resulting in a low explosive energy per unit volume (volume energy density); 2) Due to its low density, its detonation velocity and intensity are relatively low, limiting its effect on breaking hard rocks; 3) Poor water resistance: Traditional expanded ammonium nitrate explosives are highly hygroscopic and tend to clump together when exposed to moisture, leading to decreased sensitivity and even "partial explosion" or "explosion failure". Summary of the Invention

[0003] The technical problem to be solved by this invention is: how to increase the bulk density of expanded ammonium nitrate explosive.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a high-density expanded ammonium nitrate explosive, which, by weight, comprises the following raw materials: 78-83.2 parts ammonium nitrate, 4-4.5 parts composite oil phase, 4-5 parts wood flour, 9-14 parts porous granular ammonium nitrate, and 0.2-0.3 parts metal salt.

[0005] Another technical solution adopted in this invention is: the preparation method of the above-mentioned high-density expanded ammonium nitrate explosive includes the following steps: S1: An aqueous phase is prepared using water, ammonium nitrate, and metal salts; the composite oil phase is then melted. S2: Mix the aqueous phase and the molten composite oil phase and then expand them. Add porous granular ammonium nitrate and wood flour to mix the explosives and obtain high-density expanded ammonium nitrate explosive.

[0006] The beneficial effects of this invention are as follows: Based on the basic principle of oxygen balance in industrial explosive formulation design, the expanded ammonium nitrate explosive of this invention improves the explosive density through two steps: 1. Reducing the amount of ammonium nitrate and adding porous granular ammonium nitrate, utilizing the greater packing density of porous granular ammonium nitrate to increase the explosive packing density; 2. Utilizing the salt modification and crystallization control characteristics of aqueous phase additives (metal salts) to increase the explosive density. Aqueous phase additives have the function of filling pores and improving the crystal structure of ammonium nitrate. Through formulation design, adding an appropriate amount of aqueous phase additives can increase the density of expanded ammonium nitrate explosives. Detailed Implementation

[0007] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments.

[0008] This invention is applicable to mountain blasting, and high-density expanded ammonium nitrate explosive is obtained by adjusting the formula and the content of its components.

[0009] A high-density expanded ammonium nitrate explosive, by weight, comprises the following raw materials: 78-83.2 parts ammonium nitrate, 4-4.5 parts composite oil phase, 4-5 parts wood flour, 9-14 parts porous granular ammonium nitrate, and 0.2-0.3 parts metal salt.

[0010] As can be seen from the above description, the beneficial effects of this invention are as follows: the industrial explosive formulation design follows the basic principle of oxygen balance. When the formulation is at or near zero oxygen balance, the products of the explosion reaction are likely to be all or almost all water and carbon dioxide, at which point the heat released is the greatest, and the blasting or work effect is optimal. Based on the above principle, this invention improves the explosive density through two steps: 1. Reducing the amount of ammonium nitrate and adding a higher content of porous granular ammonium nitrate, utilizing the greater packing density of porous granular ammonium nitrate to increase the explosive packing density; 2. Utilizing the salt modification and crystallization control characteristics of aqueous phase additives (metal salts) to increase the explosive density. Aqueous phase additives have the function of filling pores and improving the crystal structure of ammonium nitrate, reducing the internal pores of ammonium nitrate crystals. Through formulation design, adding an appropriate amount of aqueous phase additives can increase the density of expanded ammonium nitrate explosives; and because aqueous phase additives can form a dense coating layer, they also play a role in isolating moisture and improving water resistance.

[0011] The bulk density of ordinary expanded ammonium nitrate explosives is >0.42 g / cm³. 3 The bulk density of the expanded ammonium nitrate explosive of the present invention is ≥0.56 g / cm³. 3 Compared with ordinary expanded ammonium nitrate explosives, the expanded ammonium nitrate explosives of the present invention have increased density by 33%, and relatively increased detonation velocity and intensity, making them suitable for blasting medium-hard and harder rocks.

[0012] Preferably, the amount of metal salt added is 0.25 to 0.3 parts.

[0013] As can be seen from the above description, by conducting a single-factor comparative experiment with five sets of data (0 parts, 0.1 parts, 0.2 parts, 0.25 parts, and 0.3 parts respectively), the results showed that the experimental results were best when the content of the aqueous additive was 0.25 parts, and its bulk density was the largest.

[0014] Furthermore, the complex oil phase includes biodiesel, paraffin, and lubricating oil base oil.

[0015] Furthermore, the metal salt is at least one of NaNO3, Na2SO4 and Mg(NO3)2.

[0016] Preferably, the metal salt is Na2SO4 or Mg(NO3)2.

[0017] As can be seen from the above description, Na2SO4 has strong crystal refinement and high charge density, and its resistance to moisture absorption and agglomeration is better than that of sodium nitrate. It can increase the decomposition initiation temperature of ammonium nitrate and enhance thermal stability. Mg(NO3)2 has strong crystal modification and significantly increased density. At the same time, it reduces moisture absorption, improves oxygen balance, and increases detonation velocity and sympathetic detonation. Its overall performance improvement is far greater than that of sodium nitrate.

[0018] Another technical solution adopted in this invention is: the preparation method of the above-mentioned high-density expanded ammonium nitrate explosive includes the following steps: S1: An aqueous phase is prepared using water, ammonium nitrate, and metal salts; the composite oil phase is then melted. S2: Mix the aqueous phase and the molten composite oil phase and then expand them. Add porous granular ammonium nitrate and wood flour to mix the explosives and obtain high-density expanded ammonium nitrate explosive.

[0019] As can be seen from the above description, the present invention dissolves ammonium nitrate in water, then mixes it with a composite oil phase in a liquid state, and then performs continuous vacuum expansion to obtain high-density expanded ammonium nitrate explosive. This preparation method is simple and easy to promote.

[0020] Furthermore, the residue on ignition of ammonium nitrate is ≤0.04wt%, and the free water content of ammonium nitrate is ≤0.5wt%.

[0021] As can be seen from the above description, limiting the content of ammonium nitrate calcination residue and free water can prevent impurities from damaging the oil film structure and affecting the viscosity of the explosive, prevent water from diluting the composite oil phase and causing material stratification, ensure the stability of high-viscosity explosive components and uniform detonation performance, and improve production and storage safety.

[0022] Furthermore, the aqueous phase is kept at 120~135℃ after preparation.

[0023] As described above, excessively low aqueous phase insulation temperatures can lead to incomplete dissolution of inorganic salt additives and uneven material mixing, which is detrimental to the stable molding of high-viscosity systems. Excessively high temperatures can exacerbate water evaporation, induce thermal decomposition of ammonium nitrate, disrupt the oil-water system balance, and cause fluctuations in explosive performance and safety hazards. Reasonable control of the aqueous phase insulation temperature ensures complete dissolution of all components, uniform system performance, and stable explosive viscosity and overall quality.

[0024] Furthermore, the mass ratio of water to ammonium nitrate is 1:12~13.

[0025] Furthermore, when ammonium nitrate in S1 comes into contact with water, the water temperature is not lower than 60°C.

[0026] As can be seen from the above description, limiting the temperature of the liquid in the tank to no less than 60°C when feeding ammonium nitrate ensures that the ammonium nitrate dissolves quickly and completely, avoiding local crystallization, agglomeration and precipitation; it also prevents incomplete dissolution of raw materials from causing uneven mixing of components, ensures the uniformity and stability of the aqueous system, facilitates the formation of high-viscosity explosive oil film and overall viscosity stability, reduces impurity precipitation, and improves product consistency and production stability.

[0027] Furthermore, the kinematic viscosity of the composite oil phase after melting is 6.5~9.5 (100℃) mm. 2 / s.

[0028] Furthermore, the oil content of the composite oil phase is ≤35wt%.

[0029] Preferably, the oil content of the composite oil phase is 20~35wt%.

[0030] Furthermore, the composite oil phase has a dropping melting point of 55~80℃, a penetration of 60~80 (0.1mm), and a flash point ≥200℃.

[0031] As can be seen from the above description, limiting the kinematic viscosity, oil content, dropping melting point, penetration and flash point of the composite oil phase can stabilize the physical and chemical properties and binding and coating ability of the composite oil phase, ensure that the adsorption and coating effect of the composite oil phase on ammonium nitrate particles is uniform and consistent, and prevent the composite oil phase from precipitation, flow and stratification.

[0032] Furthermore, the melting temperature of the composite oil phase is 70~90℃.

[0033] Furthermore, the puffing is performed using a puffing crystallizer, wherein the temperature of the puffing crystallizer is 80~110℃ and the pressure is ≥0.060Mpa.

[0034] As described above, temperature and pressure determine the pore structure of expanded ammonium nitrate. Lower parameters result in insufficient expansion, weak oil absorption, and poor explosive viscosity; higher parameters lead to brittle particles and decreased stability. Pressure fluctuations before expansion cause uneven material structure and differences in the adsorption of the composite oil phase, resulting in unstable product viscosity and performance.

[0035] Furthermore, before expansion, the pressure inside the expansion crystallizer is ≤-0.060 MPa.

[0036] Preferably, before expansion, the pressure inside the expansion crystallizer is -0.070 to -0.060 MPa.

[0037] Furthermore, a dynamic mixer is used during mixing, with a frequency of 10~20Hz and a rotation speed of 100~200 r / min.

[0038] Furthermore, the temperature of the aqueous phase before mixing is 120~135℃, and the temperature of the composite oil phase is 70~95℃.

[0039] As described above, limiting the expanded aqueous phase temperature to 120–135℃ and the composite oil phase temperature to 70–95℃ is to ensure complete dissolution of salts in the aqueous phase and system stability, while preventing high-temperature aging, deterioration, and viscosity loss in the composite oil phase. This temperature refers to the temperature before entering the mixer.

[0040] Furthermore, the moisture content of the mixed powder is ≤0.15wt%, and the temperature is ≤55℃.

[0041] As can be seen from the above description, limiting the moisture content after mixing the drugs is necessary to prevent excessive moisture from diluting the composite oil phase, reducing the viscosity of the drug, and avoiding moisture absorption, clumping, and performance degradation. Temperature control is crucial: excessively high temperatures can cause the loss of the composite oil phase and a decrease in the stability of the explosive, while excessively low temperatures can lead to crystallization. This ensures that the viscosity and composition of the explosive are uniform and that the product quality is stable.

[0042] Example 1 of the present invention is: a high-density expanded ammonium nitrate explosive, which is composed of the following raw materials by weight: 78 kg ammonium nitrate, 4 kg composite oil phase, 4 kg wood flour, 9 kg porous granular ammonium nitrate, and 0.1 kg NaNO3; the composite oil phase is composed of biodiesel, paraffin wax, and lubricating oil base oil in a mass ratio of 3:3:4.

[0043] Example 2 of the present invention is: a high-density expanded ammonium nitrate explosive, which is composed of the following raw materials by weight: 80.6 kg ammonium nitrate, 4.25 kg composite oil phase, 4.5 kg wood flour, 11.5 kg porous granular ammonium nitrate, and 0.175 kg Na2SO4; the composite oil phase is composed of biodiesel, paraffin wax, and lubricating oil base oil in a mass ratio of 3:3:4.

[0044] Example 3 of the present invention is: a high-density expanded ammonium nitrate explosive, which is composed of the following raw materials by weight: 83.2 kg ammonium nitrate, 4.5 kg composite oil phase, 5 kg wood flour, 14 kg porous granular ammonium nitrate, 0.1 kg NaNO3, and 0.15 kg Na2SO4; the composite oil phase is composed of biodiesel, paraffin wax, and lubricating oil base oil in a mass ratio of 3:3:4.

[0045] Example 4 of the present invention is a method for preparing high-density expanded ammonium nitrate explosive, the specific steps of which are as follows: S1: Mix the raw materials ammonium nitrate and composite oil phase according to the ratio, start the ammonium nitrate crusher and screw feeder, and after the equipment is running smoothly, feed the materials according to the command from the control panel. The ammonium nitrate meets the technical requirements of GB / T2944-2017 and Table 1, and the composite oil phase meets the technical requirements of Table 2. Table 1

[0046] Table 2

[0047] S2: Calculate the required amounts of water, ammonium nitrate, and metal salt for the aqueous phase preparation. The mass ratio of water to ammonium nitrate is 1:12.5. Add water to the aqueous phase preparation tank according to the mixing ratio, start the steam valve and the agitator of the aqueous phase preparation tank at a speed of 40 r / min, raise the temperature to 60℃, add ammonium nitrate and metal salt, raise the temperature to 130℃, and continue stirring until the ammonium nitrate and metal salt are completely dissolved to obtain the aqueous phase. During this process, the steam pressure in the insulation jacket of the aqueous phase preparation tank should not exceed 0.3 MPa, and the steam pressure in the coil heating should not exceed 0.4 MPa. Calculate the amount of composite oil phase to be added, start the agitator of the wax melting tank and the oil phase preparation tank, and add biodiesel, paraffin and lubricating oil base oil in a mass ratio of 3:3:4 to the wax melting tank at 80℃ according to the ingredient ratio. After the biodiesel, paraffin and lubricating oil base oil melt, the composite oil phase is prepared and the melting vapor pressure is ≤0.20MPa. S3: Open the steam valve to preheat the dynamic mixer, the extrusion crystallizer, and their pipelines. Pump the 130℃ aqueous and 80℃ oil phase solutions into the water and oil phase storage tanks. Then, evacuate the extrusion crystallizer to ensure that the pressure inside the extrusion crystallizer is ≤-0.060Mpa. Start the dynamic mixer, set the frequency of the dynamic mixer to 15Hz, and the operating speed to 150r / min. Pump the water and oil phase solutions from the water and oil phase storage tanks into the dynamic mixer for mixing. During the mixing process, the steam pressure in the ammonium nitrate solution and oil phase delivery pipelines, as well as the dynamic mixer, should be ≤0.2MPa. S4: The mixed material flows into the expansion crystallizer by gravity. The temperature of the expansion crystallizer is 95℃, the pressure is 0.060Mpa, and the spindle speed is 1r / min. During the expansion process, the pressure of the preheating steam on the chassis of the expansion crystallizer and the heat preservation steam in the feed pipe is ≤0.2MPa. S5: The expanded material is mixed with porous granular ammonium nitrate and wood flour through a functional additive conveying screw. The moisture content of the mixed powder is ≤0.15wt% and the temperature is ≤55℃. Then it is conveyed to the roller press through a sealed discharge screw. S6: After passing through the roller press, the material is conveyed to the loading machine via a cooling mixing spiral, an explosion-proof belt, and a material spiral. S7: After the mixed explosives have cooled, they are loaded into bags using a loading machine. Each bag weighs 25±0.25kg. The finished bagged explosives should be stacked neatly, with no more than 10 bags per layer.

[0048] Example 5 of the present invention is a method for preparing high-density expanded ammonium nitrate explosive, the specific steps of which are as follows: S1: Mix the raw materials ammonium nitrate and composite oil phase according to the ratio, start the ammonium nitrate crusher and screw feeder, and after the equipment is running smoothly, feed the materials according to the command from the control panel. The ammonium nitrate meets the technical requirements of GB / T2944-2017 and Table 3, and the composite oil phase meets the technical requirements of Table 4. Table 3

[0049] Table 4

[0050] S2: Calculate the required amounts of water, ammonium nitrate, and metal salt for the aqueous phase preparation. The mass ratio of water to ammonium nitrate is 1:12. Add water to the aqueous phase preparation tank according to the mixing ratio, start the steam valve and the agitator of the aqueous phase preparation tank at a speed of 40 r / min, raise the temperature to 65℃, add ammonium nitrate and metal salt, raise the temperature to 120℃, and continue stirring until the ammonium nitrate and metal salt are completely dissolved to obtain the aqueous phase. During this process, the steam pressure in the insulation jacket of the aqueous phase preparation tank should not exceed 0.3 MPa, and the steam pressure in the coil heating should not exceed 0.4 MPa. Calculate the amount of composite oil phase to be added, start the agitator of the wax melting tank and the oil phase preparation tank, and add biodiesel, paraffin and lubricating oil base oil in a mass ratio of 3:3:4 to the wax melting tank at 70℃ according to the ingredient ratio. After the biodiesel, paraffin and lubricating oil base oil melt, the composite oil phase is prepared. The melting vapor pressure is ≤0.20MPa. S3: Open the steam valve to preheat the dynamic mixer, the extrusion crystallizer, and their pipelines. Pump the 120℃ aqueous and 70℃ oil phase solutions into the water and oil phase storage tanks. Then, evacuate the extrusion crystallizer to ensure the internal pressure is -0.065 MPa. Start the dynamic mixer, set its frequency to 10 Hz, and its operating speed to 100 r / min. Pump the water and oil phase solutions from the water and oil phase storage tanks into the dynamic mixer for mixing. During the mixing process, the steam pressure in the ammonium nitrate solution and oil phase delivery pipelines, as well as the dynamic mixer, should be ≤0.2 MPa. S4: The mixed material flows into the extrusion crystallizer by gravity. The temperature of the extrusion crystallizer is 80℃, the pressure is 0.065Mpa, and the spindle speed is 1r / min. During the extrusion process, the pressure of the preheating steam on the chassis of the extrusion crystallizer and the heat preservation steam in the feed pipe is ≤0.2MPa. S5: The expanded material is mixed with porous granular ammonium nitrate and wood flour through a functional additive conveying screw. The moisture content of the mixed powder is ≤0.15wt% and the temperature is ≤55℃. Then it is conveyed to the roller press through a sealed discharge screw. S6: After passing through the roller press, the material is conveyed to the loading machine via a cooling mixing spiral, an explosion-proof belt, and a material spiral. S7: After the mixed explosives have cooled, they are loaded into bags using a loading machine. Each bag weighs 25±0.25kg. The finished bagged explosives should be stacked neatly, with no more than 10 bags per layer.

[0051] Example 6 of the present invention is a method for preparing high-density expanded ammonium nitrate explosive, the specific steps of which are as follows: S1: Mix the raw materials ammonium nitrate and composite oil phase in the correct proportions, start the ammonium nitrate crusher and screw feeder, and after the equipment is running smoothly, feed the materials according to the command from the control panel. The ammonium nitrate meets the technical requirements of GB / T2944-2017 and Table 5, and the composite oil phase meets the technical requirements of Table 6. Table 5

[0052] Table 6

[0053] S2: Calculate the required amounts of water, ammonium nitrate, and metal salt for the aqueous phase preparation. The mass ratio of water to ammonium nitrate is 1:13. Add water to the aqueous phase preparation tank according to the mixing ratio, start the steam valve and the agitator of the aqueous phase preparation tank, with a rotation speed of 40 r / min, raise the temperature to below 60℃, add ammonium nitrate and metal salt, raise the temperature to 135℃, and continue stirring until the ammonium nitrate and metal salt are completely dissolved to obtain the aqueous phase. During this process, the steam pressure in the insulation jacket of the aqueous phase preparation tank should not exceed 0.3 MPa, and the steam pressure in the coil heating should not exceed 0.4 MPa. Calculate the amount of composite oil phase to be added, start the agitator of the wax melting tank and the oil phase preparation tank, and add biodiesel, paraffin and lubricating oil base oil in a mass ratio of 3:3:4 to the wax melting tank at 90℃ according to the ingredient ratio. After the biodiesel, paraffin and lubricating oil base oil melt, the composite oil phase is prepared and the melting vapor pressure is ≤0.20MPa. S3: Open the steam valve to preheat the dynamic mixer, the extrusion crystallizer, and their pipelines. Pump the 135℃ aqueous and 90℃ oil phase solutions into the water and oil phase storage tanks. Then, evacuate the extrusion crystallizer to ensure the internal pressure is -0.070 MPa. Start the dynamic mixer, set its frequency to 20Hz, and its operating speed to 200 r / min. Pump the water and oil phase solutions from the water and oil phase storage tanks into the dynamic mixer for mixing. During the mixing process, the steam pressure in the ammonium nitrate solution and oil phase delivery pipelines, as well as the dynamic mixer, should be ≤0.2 MPa. S4: The mixed material flows into the extrusion crystallizer by gravity. The temperature of the extrusion crystallizer is 110℃, the pressure is 0.070Mpa, and the spindle speed is 1r / min. During the extrusion process, the pressure of the preheating steam on the chassis of the extrusion crystallizer and the heat preservation steam in the feed pipe is ≤0.2MPa. S5: The expanded material is mixed with porous granular ammonium nitrate and wood flour through a functional additive conveying screw. The moisture content of the mixed powder is ≤0.15wt% and the temperature is ≤55℃. Then it is conveyed to the roller press through a sealed discharge screw. S6: After passing through the roller press, the material is conveyed to the loading machine via a cooling mixing spiral, an explosion-proof belt, and a material spiral. S7: After the mixed explosives have cooled, they are loaded into bags using a loading machine. Each bag weighs 25±0.25kg. The finished bagged explosives should be stacked neatly, with no more than 10 bags per layer.

[0054] The formulation of expanded ammonium nitrate explosive was validated using the preparation method of Example 4. The validation results are shown in Table 7. Table 7

[0055] As shown in Table 7, adding metal salts as water-based additives and replacing part of the ammonium nitrate with porous granular ammonium nitrate can improve bulk density, detonation velocity, and saturation; using Mg(NO3)2 as a metal salt has a better effect on improving detonation velocity.

[0056] In summary, the expanded ammonium nitrate explosive and its preparation method provided by this invention have the following advantages: (1) The above technical solution can bring the following advantages: Advantage 1: Increased density, significantly increasing volumetric energy density.

[0057] Advantage 2: Increased detonation velocity, enhanced intensity and work capacity, suitable for blasting medium-hard and harder rocks.

[0058] (1) Adding 0.2~0.3 parts by weight of aqueous phase additives (NaNO3, Na2SO4, Mg(NO3)2) can fill microbubbles, compact the gaps between particles, and reduce porosity; thus optimizing the crystal structure of inorganic salts, reducing internal pores and increasing the packing density of explosives; at the same time, adding porous granular ammonium nitrate can utilize the greater packing density of porous granular ammonium nitrate to increase the packing density of explosives.

[0059] (2) Increased density makes the detonation wave propagation more continuous, improves energy density, significantly improves fragmentation efficiency and sympathetic detonation distance, enhances hardness and work capacity, and is suitable for blasting medium-hard and above rocks.

[0060] (3) The aqueous phase additive forms a dense coating layer to isolate moisture; Na2SO4 can increase the decomposition initiation temperature of ammonium nitrate and enhance thermal stability.

[0061] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made using the present invention specification, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A high-density expanded ammonium nitrate explosive, characterized in that, By weight, it includes the following raw materials: 78-83.2 parts ammonium nitrate, 4-4.5 parts composite oil phase, 4-5 parts wood flour, 9-14 parts porous granular ammonium nitrate, and 0.2-0.3 parts metal salt.

2. The high-density expanded ammonium nitrate explosive according to claim 1, characterized in that, The composite oil phase includes biodiesel, paraffin wax, and lubricating oil base oil.

3. The high-density expanded ammonium nitrate explosive according to claim 1, characterized in that, The metal salt is at least one of NaNO3, Na2SO4 and Mg(NO3)2.

4. The method for preparing high-density expanded ammonium nitrate explosive as described in any one of claims 1-3, characterized in that, Includes the following steps: S1: An aqueous phase is prepared using water, ammonium nitrate, and metal salts; the composite oil phase is then melted. S2: Mix the aqueous phase and the molten composite oil phase and then expand them. Add porous granular ammonium nitrate and wood flour to mix the explosives and obtain high-density expanded ammonium nitrate explosive.

5. The method for preparing high-density expanded ammonium nitrate explosive according to claim 4, characterized in that, The aqueous phase is then kept at 120~135℃ after preparation.

6. The method for preparing high-density expanded ammonium nitrate explosive according to claim 4, characterized in that, The mass ratio of water to ammonium nitrate is 1:12~13.

7. The method for preparing high-density expanded ammonium nitrate explosive according to claim 4, characterized in that, When ammonium nitrate in S1 comes into contact with water, the water temperature is not lower than 60°C.

8. The method for preparing high-density expanded ammonium nitrate explosive according to claim 4, characterized in that, The kinematic viscosity of the composite oil phase after melting is 6.5~9.5 (100℃) mm. 2 / s.

9. The method for preparing high-density expanded ammonium nitrate explosive according to claim 4, characterized in that, The oil content of the composite oil phase is ≤35wt%.

10. The method for preparing high-density expanded ammonium nitrate explosive according to claim 4, characterized in that, The puffing process is performed using a puffing crystallizer, with a temperature of 80~110℃ and a pressure ≥0.060Mpa.

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