Method for preparing micro-dust smokeless sulfur-free firework powder material by taking corn flour as raw material and nitrated corn flour

Abstract

The invention belongs to the technical field of firework powder preparation, and provides a method for preparing a tiny-dust smokeless sulfur-free firework powder material by taking corn flour as a raw material and nitrated corn flour. The method comprises the following steps: mixing corn flour with a nitrating agent, and nitrating to obtain a nitrated corn flour crude product; mixing the nitrified corn flour crude product with water, and carrying out first washing; and after the first washing, adding an alkaline solution into the obtained system, and carrying out second washing to obtain the nitrated corn flour. By reasonably designing the composition of the nitrating agent, the nitration process and parameters, the nitrogen content of the obtained nitrated corn flour is 8-14.12%, and the obtained nitrated corn flour is easy to burn and basically free of residues, namely dust and smoke; the nitrogen distribution is uniform, the nitrogen content is proper, the stability is high (explosion is not prone to occurring) and the combustion safety is uniform, and the safety in the transportation and use process is guaranteed. Meanwhile, the corn flour serving as fifth natural starch is sufficient in source, wide in producing area and low in cost. In addition, the method provided by the invention is simple to operate.

Description

Technical Field

[0001] The invention relates to the technical field of fireworks agent preparation, and in particular to a method for preparing dust-free, smokeless and sulfur-free fireworks agent material by using corn powder as raw material, and nitrifying corn powder. Background Art

[0002] Previously, fireworks were made of black powder, but after the explosion, the pH value of black powder is as high as 2.5. Based on environmental protection requirements, researchers began to develop other substances as fireworks agents, such as corn flour. Corn flour is a polysaccharide carbohydrate with hydroxyl groups. When burned, it will produce thick smoke and a large amount of carbon black, which limits its application. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a method for preparing dust-free, smokeless and sulfur-free fireworks powder materials using corn powder as raw material, and nitrated corn powder. The nitrated corn powder obtained by the preparation method provided by the present invention is smokeless and substantially free of residue when burned, that is, dust-free.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing dust-free, smoke-free and sulfur-free fireworks powder material by using corn flour as raw material, comprising the following steps:

[0006] The corn flour and the nitrifying agent are mixed and nitrated to obtain a crude nitrated corn flour;

[0007] The crude nitrated corn meal is mixed with water and subjected to a first washing;

[0008] After the first washing, an alkaline solution is added to the obtained system, and a second washing is performed to obtain nitrated corn flour;

[0009] The nitrating agent comprises nitric acid, a catalyst and a nitrating protective agent;

[0010] The mass fraction of the nitric acid is 55-98%;

[0011] The nitrification protective agent is ammonium nitrate, potassium nitrate, sodium nitrate or sodium nitrite;

[0012] The catalyst is concentrated sulfuric acid or acetic anhydride, and the mass fraction of the concentrated sulfuric acid is 98%;

[0013] The mass ratio of the nitric acid to the catalyst is 0.6 to 5.5:1;

[0014] The mass of the nitrification protective agent is 0.5 to 15% of the mass of the nitric acid;

[0015] The mass ratio of the corn flour to the nitrifying agent is 1:2-9;

[0016] The nitrification comprises sequentially performing a first nitrification and a second nitrification;

[0017] The temperature of the first nitration is 10-25° C., the time is 20-60 min, and the first nitration is carried out under normal pressure;

[0018] The temperature of the second nitration is 25-30° C., and the time is 20-30 min. The second nitration is carried out under nitrogen and sealed conditions.

[0019] Preferably, the particle size of the corn flour is 0.2 to 25 μm;

[0020] The preparation method of the corn flour comprises the following steps:

[0021] The corn kernels are sequentially subjected to a first drying, a pulverizing, and a second drying to obtain the corn flour;

[0022] The moisture content of the corn flour is ≤5%;

[0023] Before the corn flour is mixed with the nitrifying agent, the method further comprises: drying the corn flour at a temperature of 80° C. for a time of 8 to 12 hours.

[0024] Preferably, the preparation method of the nitrating agent comprises the following steps:

[0025] first mixing nitric acid and a catalyst to obtain a mixed solution;

[0026] The mixed solution and the nitration protective agent are mixed for a second time to obtain the nitration agent.

[0027] Preferably, the temperature of the first mixing is -5 to 0°C; the first mixing is performed under stirring, and the stirring speed is 400 to 600 rpm;

[0028] The temperature of the second mixing is 5-10° C., and the time is 1-2 hours.

[0029] Preferably, mixing corn flour and nitrifying agent comprises: adding corn flour to nitrifying agent, during the process of adding corn flour, the temperature is 10-25° C., and the stirring speed is 150-200 rpm.

[0030] Preferably, after the nitrification, the process further comprises: filtering and collecting filter residues; washing and dehydrating the filter residues in sequence to obtain crude nitrated corn flour.

[0031] Preferably, the mass ratio of the crude nitrated corn flour to water is 1:1-2, the rotation speed of the first washing is 50-100 rpm, the temperature is 100-110° C., and the time is 10-50 min.

[0032] Preferably, the mass fraction of the alkaline solution is 2-6%, the alkali in the alkaline solution is an inorganic alkali, and the inorganic alkali is sodium carbonate or sodium bicarbonate;

[0033] The mass ratio of the crude nitrated corn flour to the alkaline solution is 1:0.05-0.5;

[0034] The second washing has a rotation speed of 50-100 rpm, a temperature of 100-110° C., and a time of 30-60 min.

[0035] Preferably, after the second washing, the method further comprises: filtering the obtained feed liquid and collecting the filter residue; washing, dehydrating and drying the filter residue in sequence to obtain nitrated corn flour; the number of washings is 3 to 5 times; the drying temperature is 20 to 60° C., the vacuum degree is 125 to 520 mmHg, and the drying time is 8 to 24 hours.

[0036] The present invention also provides nitrated corn flour obtained by the method described in the above technical scheme. The nitrated corn flour is dust-free, smoke-free and sulfur-free, and the nitrogen content of the nitrated corn flour is 8-14.12%.

[0037] The invention provides a method for preparing fine dust, smokeless and sulfur-free fireworks powder material by taking corn flour as raw material.

[0038] The present invention reasonably designs the composition of the nitrifying agent, the nitrification process and the parameters, so that the nitrogen content of the obtained nitrated corn flour is 8-14.12%, it is easy to burn, and basically does not produce smoke and dust, that is, it is dust-free; the nitrogen distribution is uniform and combined with the appropriate nitrogen content, so that the nitrated corn flour has high stability (not easy to explode) and uniform combustion safety, ensuring the safety during transportation and use. At the same time, corn flour, as the fifth largest natural starch, has sufficient sources, a wide range of production areas, and low costs. In addition, the method provided by the present invention is simple to operate. DETAILED DESCRIPTION

[0039] The present invention provides a method for preparing dust-free, smoke-free and sulfur-free fireworks powder material by using corn flour as raw material, comprising the following steps:

[0040] The corn flour and the nitrifying agent are mixed and nitrated to obtain a crude nitrated corn flour product;

[0041] The crude nitrated corn meal is mixed with water and subjected to a first washing;

[0042] After the first washing, an alkaline solution is added to the obtained system, and a second washing is performed to obtain nitrated corn flour;

[0043] The nitrating agent comprises nitric acid, a catalyst and a nitrating protective agent;

[0044] The mass fraction of the nitric acid is 55-98%;

[0045] The nitrification protective agent is ammonium nitrate, potassium nitrate, sodium nitrate or sodium nitrite;

[0046] The catalyst is concentrated sulfuric acid or acetic anhydride, and the mass fraction of the concentrated sulfuric acid is 98%;

[0047] The mass ratio of the nitric acid to the catalyst is 0.6 to 5.5:1;

[0048] The mass of the nitrification protective agent is 0.5 to 15% of the mass of the nitric acid;

[0049] The mass ratio of the corn flour to the nitrifying agent is 1:2-9;

[0050] The nitrification comprises sequentially performing a first nitrification and a second nitrification;

[0051] The temperature of the first nitration is 10-25° C., the time is 20-60 min, and the first nitration is carried out under normal pressure;

[0052] The temperature of the second nitration is 25-30° C., and the time is 20-30 min. The second nitration is carried out under nitrogen and sealed conditions.

[0053] In the present invention, unless otherwise specified, the raw materials used in the present invention are preferably commercially available products.

[0054] The invention mixes corn flour and a nitrifying agent, performs nitration, and obtains crude nitrated corn flour.

[0055] In the present invention, the particle size of the corn flour is preferably 0.2 to 25 μm. In the present invention, the method for preparing the corn flour preferably comprises the following steps: subjecting corn kernels to first drying, crushing and second drying in sequence to obtain the corn flour. In the present invention, the moisture content of the corn flour is preferably ≤5%. The present invention does not specifically limit the temperature and time of the first drying and the second drying, as long as the moisture content of the corn flour can be guaranteed to be ≤5%. The present invention does not specifically limit the parameters of the crushing, as long as the particle size of the corn flour can be 0.2 to 25 μm.

[0056] Before the corn flour is mixed with the nitrifying agent, the present invention preferably further comprises: drying the corn flour; the drying temperature is preferably 80° C.; the drying time is preferably 8 to 12 hours, and more preferably 10 hours.

[0057] In the present invention, the nitrating agent includes nitric acid, a catalyst and a nitration protective agent. In the present invention, the mass fraction of the nitric acid is 55-98%, specifically 55%, 60%, 65%, 68%, 70%, 75%, 80%, 85%, 90% or 98%. In the present invention, the nitration protective agent is ammonium nitrate, potassium nitrate, sodium nitrate or sodium nitrite. In the present invention, the mass of the nitration protective agent is 0.5-15% of the mass of the nitric acid, preferably 1-10%, specifically 1%, 1.67%, 2%, 3%, 5%, 8%, 10%, 11.1%, 14.3% or 15%. In the present invention, the catalyst is concentrated sulfuric acid or acetic anhydride; the mass fraction of the concentrated sulfuric acid is 98%. In the present invention, the mass ratio of the nitric acid to the catalyst is 0.6 to 5.5: 1, specifically 0.6: 1, 0.7: 1, 0.75: 1, 0.8: 1, 1: 1, 1.67: 1, 2: 1, 2.5: 1, 3: 1, 4: 1, 5: 1 or 5.5: 1. In the present invention, the concentrated sulfuric acid in the catalyst also has the function of a dehydrating agent.

[0058] In the present invention, the preparation method of the nitrating agent preferably comprises the following steps:

[0059] first mixing nitric acid and a catalyst to obtain a mixed solution;

[0060] The mixed solution and the nitration protective agent are mixed for a second time to obtain the nitration agent.

[0061] In the present invention, the temperature of the first mixing is preferably -5 to 0°C, specifically preferably -5°C; the first mixing is preferably carried out under stirring, and the stirring speed is preferably 400 to 600 rpm, more preferably 500 to 550 rpm; the present invention does not specifically limit the time of the first mixing, as long as the nitric acid and the catalyst protective agent can be fully dissolved and mixed.

[0062] In the present invention, the temperature of the second mixing is preferably 5 to 10° C., specifically preferably 5° C., and the time is preferably 1 to 2 hours, specifically preferably 2 hours.

[0063] In the present invention, the mass ratio of the corn flour to the nitrifying agent is 1:2-9, preferably 1:3-6, and specifically can be 1:2.83, 1:3.36, 1:4, 1:4.2, 1:4.47, 1:4.91, 1:5, 1:5.25, 1:5.37, 1:5.67, 1:6, 1:7 or 1:8.

[0064] In the present invention, mixing corn flour and nitrifying agent preferably comprises: adding corn flour to nitrifying agent; during the process of adding corn flour, the temperature is preferably 10-25° C., and the stirring speed is preferably 150-200 rpm.

[0065] In the present invention, the nitration includes sequentially performing a first nitration and a second nitration.

[0066] In the present invention, the temperature of the first nitration is 10-25° C., the time is 20-60 min, and the first nitration is carried out under normal pressure.

[0067] In the present invention, the temperature of the second nitration is 25-30° C., and the time is 20-30 min; the second nitration is carried out under nitrogen and sealed conditions.

[0068] After the nitrification, the present invention preferably further comprises: filtering and collecting the filter residue; washing and dehydrating the filter residue in sequence to obtain a crude nitrated corn flour. In the present invention, the filtration is preferably performed in a centrifuge. In the present invention, the number of times of washing is preferably 3 times.

[0069] After obtaining the crude nitrified corn flour, the present invention mixes the crude nitrified corn flour with water and performs a first washing.

[0070] In the present invention, the water is preferably deionized water. In the present invention, the mass ratio of the crude nitrated corn flour to water is preferably 1:1-2. In the present invention, the rotation speed of the first washing is preferably 50-100 rpm, more preferably 60-90 rpm, more preferably 70-80 rpm; the temperature is preferably 100-110°C, and the time is preferably 10-50 min.

[0071] After the first washing, the present invention adds an alkaline solution to the obtained system and performs a second washing to obtain nitrated corn flour.

[0072] In the present invention, the mass fraction of the alkaline solution is preferably 2-6%, specifically 3.5%, 4%, 4.5%, 5% or 5.5%; the alkali in the alkaline solution is preferably an inorganic alkali, and the inorganic alkali is preferably sodium carbonate or sodium bicarbonate.

[0073] In the present invention, the mass ratio of the crude nitrated corn flour to the alkaline solution is preferably 1:0.05-0.5, specifically 1:061, 1:0.182, 1:0.185 or 1:0.253.

[0074] In the present invention, the rotation speed of the second washing is preferably 50 to 100 rpm, more preferably 60 to 90 rpm, and more preferably 70 to 80 rpm; the temperature is preferably 100 to 110° C., and the time is preferably 30 to 60 min.

[0075] In the present invention, the first washing and the second washing are preferably carried out in a pressure-resistant four-port device, and the pressure-resistant four-port device is preferably equipped with a reflux condensation device.

[0076] After the second washing, the present invention preferably further comprises: filtering the obtained feed liquid, collecting the filter residue; washing, dehydrating and drying the filter residue in sequence to obtain nitrated corn flour. In the present invention, the number of washing is preferably 3 to 5 times; the drying temperature is preferably 20 to 60°C, the vacuum degree is preferably 125 to 520 mmHg, specifically 150 mmHg, 200 mmHg, 250 mmHg, 280 mmHg, 320 mmHg, 375 mmHg, 420 mmHg, 430 mmHg, 460 mmHg, 490 mmHg, 512 mmHg, 515 mmHg or 520 mmHg, and the time is preferably 8 to 24 hours.

[0077] The present invention also provides nitrated corn flour obtained by the method described in the above technical scheme. The nitrated corn flour is dust-free, smoke-free and sulfur-free, and the nitrogen content of the nitrated corn flour is 8-14.12%.

[0078] In the present invention, the nitrated corn flour is easily soluble in organic solvents, easily combustible, smokeless and substantially residue-free when burned, and can be used as a substitute material for propellants, propellants, explosives, and smokeless and sulfur-free pyrotechnic powder.

[0079] The present invention does not specifically limit the application method of the nitrated corn flour, and operations familiar to those skilled in the art can be used.

[0080] The following is a detailed description of the method for preparing dust-free, smokeless and sulfur-free fireworks powder material using corn powder as raw material and nitrifying corn powder provided by the present invention in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0081] Example 1

[0082] A pressure-resistant four-mouth reaction device with a volume of 20L and filled with 5000g of 75% nitric acid by mass was half immersed in a -5°C high-precision low-temperature constant temperature reactor, 3000g of acetic anhydride was added to the nitric acid, and stirring was started at a rate of 550rpm. When the acetic anhydride was completely dissolved in the nitric acid and mixed evenly, 50g of ammonium nitrate was added to the mixed solution, the temperature was raised to 5°C, and after keeping warm for 2h, a nitrating agent was obtained.

[0083] 1500g of corn flour with a moisture content of less than 5%, a particle size of 0.2-25μm and dried at 80℃ for 10h is slowly added to the nitrating agent, and stirring is started at a rate of 160rpm. The reaction temperature is controlled at 15℃ during the stirring process. After the corn flour is added, stir for 30min, then seal the reaction device, replace the air in the reaction device with nitrogen, after replacement 3 times, raise the temperature to 25℃, continue the reaction for 30min, filter with a centrifuge to remove a large amount of acid, wash the filter residue 3 times with 3000g of water each time, dehydrate, and obtain 1756g of crude nitrated corn flour.

[0084] A pressure-resistant three-mouth device with a volume of 20L and filled with 3000g of deionized water is half immersed in a high-precision constant temperature reactor, wherein a reflux condenser is installed on the pressure-resistant four-mouth device, 1756g of crude nitrated corn flour is added to the deionized water, stirring is started at a rate of 80rpm, and the high-precision constant temperature reactor is heated to 102°C. After keeping warm for 20min, 320g of a sodium carbonate solution with a mass fraction of 4% is added thereto. After keeping warm and stirring for 60min, the filter is filtered, and the filter residue is washed 3 times with 3000mL of water each time. After dehydration and drying at 35°C and a vacuum degree of 280mmHg for 12h, 1622g of nitrated corn flour with a nitrogen content of 10.23% is obtained, and the yield is 108.1% (theoretical yield is 84.3%).

[0085] The sample (nitrated corn flour) was tested for impact sensitivity using a 5kg drop weight. The characteristic drop height of the sample was 165.68cm, indicating that the sample had very good impact stability. The friction sensitivity explosion at a 35° swing angle was 0%. The random sampling test showed that the mean square deviation of nitration of the sample was 1.89, indicating that the sample had good nitration uniformity.

[0086] Example 2

[0087] A pressure-resistant four-necked reaction flask with a volume of 2000 mL and filled with 500 g of nitric acid with a mass fraction of 68% is half immersed in a -5°C high-precision low-temperature constant-temperature reactor, 300 g of acetic anhydride is added to the nitric acid, and stirring is started at a rate of 550 rpm. When the acetic anhydride is completely dissolved in the nitric acid and mixed evenly, 50 g of potassium nitrate is added to the mixed solution, the temperature is raised to 5°C, and after keeping warm for 2 hours, a nitrating agent is obtained.

[0088] 150g of corn flour with a moisture content of less than 5%, a particle size of 0.2 to 25μm, and dried at 80°C for 10h is slowly added to the nitrating agent, and stirring is started at a rate of 150rpm. The temperature is controlled at 15°C during the stirring process. After the corn flour is added, stir for 30min, then seal the reaction device, replace the air in the reaction device with nitrogen, after replacing 3 times, raise the temperature to 25°C, continue the reaction for 26min, filter with a centrifuge to remove a large amount of acid, wash the filter residue 3 times with 300g of water each time, dehydrate, and obtain 165g of crude nitrated corn flour.

[0089] A pressure-resistant four-necked flask device with a volume of 2 mL and filled with 300 g of deionized water is half immersed in a high-precision constant temperature reactor, wherein the pressure-resistant four-necked device is equipped with a reflux condenser, 165 g of crude nitrated corn flour is added to the deionized water, stirring is started at a rate of 80 rpm, and the high-precision constant temperature reactor is heated to 100° C. After keeping warm for 25 minutes, 30 g of a sodium bicarbonate solution with a mass fraction of 4% is added thereto, and after keeping warm and stirring for 30 minutes, it is filtered, and the filter residue is washed 3 times with 300 mL of water each time. After dehydration, it is dried at 40° C. and a vacuum degree of 320 mmHg for 10 hours to obtain 158 g of nitrated corn flour with a nitrogen content of 10.35%, and the yield is 105.3% (82.3% of the theoretical yield).

[0090] The sample (nitrated corn flour) was tested for impact sensitivity using a 5kg drop weight. The characteristic drop height of the sample was 162cm, indicating that the sample had very good impact stability. The friction sensitivity explosion at a 35° swing angle was 0%. The random sampling test showed that the mean square deviation of nitration of the sample was 1.91, indicating that the sample had good nitration uniformity.

[0091] Example 3

[0092] A pressure-resistant four-mouth reaction device with a volume of 2000mL and filled with 500g of 75% nitric acid by mass concentration was half immersed in a -5°C high-precision low-temperature constant temperature reactor, 300g of acetic anhydride was added to the nitric acid, and stirring was started at a rate of 550rpm. When the acetic anhydride was completely dissolved in the nitric acid and mixed evenly, 40g of sodium nitrate was added to the mixed solution, the temperature was raised to 5°C, and the mixture was kept warm for 2h to obtain a nitrating agent.

[0093] 160g of corn flour with a moisture content of less than 5%, a particle size of 0.2 to 25μm, and dried at 80°C for 10h is slowly added to the nitrating agent, and stirring is started at a rate of 160rpm. The reaction temperature is controlled at 12°C during the stirring process. After the corn flour is added, stir for 20min, then seal the reaction device, replace the air in the reaction device with nitrogen, after replacement 3 times, raise the temperature to 26°C, continue the reaction for 25min, filter with a centrifuge to remove a large amount of acid, wash the filter residue 3 times with 300g of water each time, dehydrate, and obtain 178g of crude nitrated corn flour.

[0094] A pressure-resistant four-necked flask device with a volume of 2000 mL and filled with 300 g of deionized water is half immersed in a high-precision constant temperature reactor, wherein the pressure-resistant four-necked device is equipped with a reflux condenser, 178 g of crude nitrated corn flour is added to the deionized water, stirring is started at a rate of 60 rpm, and the high-precision constant temperature reactor is heated to 101° C. After keeping warm for 15 minutes, 45 g of a sodium carbonate solution with a mass fraction of 4% is added thereto, and after keeping warm and stirring for 45 minutes, it is filtered, and the filter residue is washed 3 times with 300 mL of water each time. After dehydration, it is dried at 50° C. and a vacuum degree of 420 mmHg for 8 hours to obtain 169 g of nitrated corn flour with a nitrogen content of 9.72%, and the yield is 105.6% (82.8% of the theoretical yield).

[0095] The sample was tested for impact sensitivity using a 5kg drop weight. The characteristic drop height of the sample was 165cm, indicating that the sample had very good impact stability. The friction sensitivity explosion at a 35° swing angle was 0%. The random sampling test showed that the mean square error of nitration of the sample was 1.89, indicating that the sample had good nitration uniformity.

[0096] Example 4

[0097] A pressure-resistant four-necked flask reaction device with a volume of 20 L and filled with 5000 g of 98% sulfuric acid by mass was half immersed in a -5°C high-precision low-temperature constant temperature reactor, 3000 g of 70% nitric acid by mass was added to the sulfuric acid, and stirring was started at a rate of 550 rpm. When the sulfuric acid and the nitric acid were completely mixed, 50 g of ammonium nitrate was added to the solution, the temperature was raised to 5°C, and the solution was kept warm for 2 hours to obtain a nitrating agent.

[0098] 1800g of corn flour with a moisture content of less than 5%, a particle size of 0.2-25μm and dried at 80℃ for 10h is slowly added to the nitrating agent, and stirring is started at a rate of 160rpm. The reaction temperature is controlled at 15℃ during the stirring process. After the corn flour is added, stir for 40min, then seal the reaction device, replace the air in the reaction device with nitrogen, after replacement 3 times, raise the temperature to 25℃, continue the reaction for 20min, filter with a centrifuge to remove a large amount of acid, wash the filter residue 3 times with 3000g of water each time, dehydrate, and obtain 1972g of crude nitrated corn flour.

[0099] A pressure-resistant four-mouth device with a volume of 20L and filled with 3000g of deionized water is half immersed in a high-precision constant temperature reactor, wherein the pressure-resistant four-mouth device is equipped with a reflux condenser, 1972g of crude nitrated corn flour is added to the deionized water, stirring is started at a rate of 80rpm, and the high-precision constant temperature reactor is heated to 101°C. After keeping warm for 25min, 120g of a sodium carbonate solution with a mass fraction of 4% is added thereto. After keeping warm and stirring for 60min, the filter is filtered, and the filter residue is washed 3 times with 3000mL of water each time. After dehydration, it is dried at 45°C and a vacuum degree of 375mmHg for 10h to obtain 1920g of nitrated corn flour with a nitrogen content of 10.23%, and the yield is 106.7% (83.5% of the theoretical yield).

[0100] The sample (nitrated corn flour) was tested for impact sensitivity using a 5kg drop weight. The characteristic drop height of the sample was 160cm, indicating that the sample had very good impact stability. The friction sensitivity explosion at a 35° swing angle was 0%. The random sampling test showed that the mean square deviation of nitration of the sample was 1.89, indicating that the sample had good nitration uniformity.

[0101] Example 5

[0102] A pressure-resistant four-mouth reaction device with a volume of 2000mL and 500g of 75% nitric acid by mass was half immersed in a -5°C high-precision low-temperature constant temperature reactor, 300g of acetic anhydride was added to the nitric acid, and stirring was started at a rate of 550rpm. When the acetic anhydride was completely dissolved in the nitric acid and mixed evenly, 40g of sodium nitrate was added to the mixed solution, the temperature was raised to 5°C, and after keeping warm for 2h, a nitrating agent was obtained.

[0103] 200g of corn flour with a moisture content of less than 5%, a particle size of 0.2 to 25μm, and dried at 80°C for 10h is slowly added to the nitrating agent, and stirring is started at a rate of 160rpm. The reaction temperature is controlled at 10°C during the stirring process. After the corn flour is added, stir for 30min, then seal the reaction device, replace the air in the reaction device with nitrogen, after replacing 3 times, raise the temperature to 25°C, continue the reaction for 30min, filter with a centrifuge to remove a large amount of acid, wash the filter residue 3 times with 400g of water each time, dehydrate, and obtain 268g of crude nitrated corn flour.

[0104] A pressure-resistant four-necked flask device with a volume of 2000 mL and filled with 400 g of deionized water is half immersed in a high-precision constant temperature reactor, wherein the pressure-resistant four-necked device is equipped with a reflux condenser, 268 g of crude nitrated corn flour is added to the deionized water, stirring is started at a rate of 60 rpm, and the high-precision constant temperature reactor is heated to 101° C. After keeping warm for 20 minutes, 40 g of a sodium carbonate solution with a mass fraction of 3.5% is added thereto, and after keeping warm and stirring for 45 minutes, it is filtered, and the filter residue is washed 3 times with 400 mL of water each time. After dehydration, it is dried at 50° C. and a vacuum degree of 460 mmHg for 8 hours to obtain 238 g of nitrated corn flour with a nitrogen content of 9.72%, and the yield is 119% (93.0% of the theoretical yield).

[0105] The sample was tested for impact sensitivity using a 5kg drop hammer. The characteristic drop height of the sample was 172cm, indicating that the sample had very good impact stability. The friction sensitivity explosion at a 35° swing angle was 0%. The random sampling test showed that the mean square error of nitration of the sample was 1.89, indicating that the sample had good nitration uniformity.

[0106] Example 6

[0107] A pressure-resistant four-mouth reaction device with a volume of 2000mL and filled with 500g of 55% nitric acid by mass was half immersed in a -5°C high-precision low-temperature constant temperature reactor, 300g of 98% sulfuric acid by mass was added to the nitric acid, and stirring was started at a rate of 500rpm. When the sulfuric acid was completely dissolved in the nitric acid and mixed evenly, 50g of sodium nitrite was added to the mixed solution, the temperature was raised to 5°C, and the nitrating agent was obtained after keeping the temperature for 2h.

[0108] 300 g of corn flour with a moisture content of less than 5%, a particle size of 0.2 to 25 μm, and dried at 80° C. for 10 hours is slowly added to the nitrating agent, and stirring is started at a rate of 160 rpm. The reaction temperature is controlled at 10° C. during the stirring process. After the corn flour is added, stir for 30 minutes, then seal the reaction device, replace the air in the reaction device with nitrogen, after replacing 3 times, raise the temperature to 28° C., continue the reaction for 30 minutes, filter with a centrifuge, remove a large amount of acid, wash the filter residue 3 times with 500 g of water each time, and dehydrate to obtain 385.6 g of crude nitrated corn flour.

[0109] A pressure-resistant four-necked flask device with a volume of 2000 mL and filled with 500 g of deionized water is half immersed in a high-precision constant temperature reactor, wherein the pressure-resistant four-necked device is equipped with a reflux condenser, 385.6 g of crude nitrated corn flour is added to the deionized water, stirring is started at a rate of 60 rpm, and the high-precision constant temperature reactor is heated to 101° C. After keeping warm for 30 minutes, 60 g of a 5% sodium bicarbonate solution is added thereto, and after keeping warm and stirring for 50 minutes, it is filtered, and the filter residue is washed 3 times with 500 mL of water each time. After dehydration, it is dried at 52° C. and a vacuum degree of 430 mmHg for 8 hours to obtain 336 g of nitrated corn flour with a nitrogen content of 9.86%, and the yield is 112% (87.7% of the theoretical yield).

[0110] The sample was tested for impact sensitivity using a 5kg drop weight. The characteristic drop height of the sample was 175cm, indicating that the sample had very good impact stability. The friction sensitivity explosion at a 35° swing angle was 0%. The random sampling test showed that the mean square error of nitration of the sample was 1.89, indicating that the sample had good nitration uniformity.

[0111] Example 7

[0112] A pressure-resistant four-mouth reaction device with a volume of 2000mL and filled with 400g of nitric acid with a mass concentration of 68% is half immersed in a -5°C high-precision low-temperature constant temperature reactor, 500g of sulfuric acid with a mass fraction of 98% is added to the nitric acid, and stirring is started at a rate of 450rpm. When the sulfuric acid is completely dissolved in the nitric acid and mixed evenly, 40g of potassium nitrate is added to the mixed solution, the temperature is raised to 5°C, and the mixture is kept warm for 2h to obtain a nitrating agent.

[0113] 280g of corn flour with a moisture content of less than 5%, a particle size of 0.2-25μm and dried at 80℃ for 10h is slowly added to the nitrating agent, and stirring is started at a rate of 160rpm. The reaction temperature is controlled at 15℃ during the stirring process. After the corn flour is added, stir for 30min, then seal the reaction device, replace the air in the reaction device with nitrogen, after replacement 3 times, raise the temperature to 25℃, continue the reaction for 30min, filter with a centrifuge to remove a large amount of acid, wash the filter residue 3 times with 450g of water each time, and dehydrate to obtain 359.8g of crude nitrated corn flour.

[0114] A pressure-resistant four-necked flask device with a volume of 2000 mL and filled with 450 g of deionized water is half immersed in a high-precision constant temperature reactor, wherein the pressure-resistant four-necked device is equipped with a reflux condenser, 359.8 g of crude nitrated corn flour is added to the deionized water, stirring is started at a rate of 70 rpm, and the high-precision constant temperature reactor is heated to 101° C. After keeping warm for 25 minutes, 60 g of a sodium carbonate solution with a mass fraction of 4.5% is added thereto, and after keeping warm and stirring for 50 minutes, it is filtered, and the filter residue is washed 3 times with 450 mL of water each time. After dehydration, it is dried at 60° C. and a vacuum degree of 515 mmHg for 8 hours to obtain 345.8 g of nitrated corn flour with a nitrogen content of 10.37%, and the yield is 123.5% (96.7% of the theoretical yield).

[0115] The sample was tested for impact sensitivity using a 5kg drop weight. The characteristic drop height of the sample was 165cm, indicating that the sample had very good impact stability. The friction sensitivity explosion at a 35° swing angle was 0%. The random sampling test showed that the mean square error of nitration of the sample was 1.89, indicating that the sample had good nitration uniformity.

[0116] Example 8

[0117] A pressure-resistant four-mouth reaction device with a volume of 2000 mL and filled with 420 g of 70% nitric acid was half immersed in a -5°C high-precision low-temperature constant temperature reactor, 600 g of 98% sulfuric acid was added to the nitric acid, and stirring was started at a rate of 550 rpm. When the sulfuric acid was completely dissolved in the nitric acid and mixed evenly, 60 g of ammonium nitrate was added to the mixed solution, the temperature was raised to 5°C, and after keeping warm for 2 hours, a nitrating agent was obtained.

[0118] 220g of corn flour with a moisture content of less than 5%, a particle size of 0.2 to 25μm, and dried at 80°C for 10h is slowly added to the nitrating agent, and stirring is started at a rate of 180rpm. The reaction temperature is controlled at 10°C during the stirring process. After the corn flour is added, stir for 30min, then seal the reaction device, replace the air in the reaction device with nitrogen, after replacement 3 times, raise the temperature to 25°C, continue the reaction for 35min, filter with a centrifuge to remove a large amount of acid, wash the filter residue 3 times with 400g of water each time, and dehydrate to obtain 293.6g of crude nitrated corn flour.

[0119] A pressure-resistant four-necked flask device with a volume of 2000 mL and filled with 400 g of deionized water was half immersed in a high-precision constant temperature reactor, wherein the pressure-resistant four-necked device was equipped with a reflux condenser, 293.6 g of crude nitrated corn flour was added to the deionized water, stirring was started at a rate of 70 rpm, and the high-precision constant temperature reactor was heated to 101° C. After keeping warm for 30 minutes, 55 g of a sodium carbonate solution with a mass fraction of 4.5% was added thereto, and after keeping warm and stirring for 60 minutes, it was filtered, and the filter residue was washed 3 times with 400 mL of water each time. After dehydration, it was dried at 60° C. and a vacuum degree of 490 mmHg for 8 hours to obtain 273.6 g of nitrated corn flour with a nitrogen content of 10.42%, and the yield was 124.36% (97.4% of the theoretical yield).

[0120] The sample was tested for impact sensitivity using a 5kg drop weight. The characteristic drop height of the sample was 165cm, indicating that the sample had very good impact stability. The friction sensitivity explosion at a 35° swing angle was 0%. The random sampling test showed that the mean square error of nitration of the sample was 1.89, indicating that the sample had good nitration uniformity.

[0121] Example 9

[0122] A pressure-resistant four-mouth reaction device with a volume of 2000mL and filled with 450g of 98% nitric acid by mass concentration was half immersed in a -5°C high-precision low-temperature constant temperature reactor, 600g of 98% sulfuric acid by mass fraction was added to the nitric acid, and stirring was started at a rate of 550rpm. When the sulfuric acid was completely dissolved in the nitric acid and mixed evenly, 50g of ammonium nitrate was added to the mixed solution, the temperature was raised to 5°C, and the mixture was kept warm for 2h to obtain a nitrating agent.

[0123] 220g of corn flour with a moisture content of less than 5%, a particle size of 0.2 to 25μm, and dried at 80°C for 10h is slowly added to the nitrating agent, and stirring is started at a rate of 180rpm. The reaction temperature is controlled at 10°C during the stirring process. After the corn flour is added, stir for 30min, then seal the reaction device, replace the air in the reaction device with nitrogen, after replacing 3 times, raise the temperature to 25°C, continue the reaction for 35min, filter with a centrifuge to remove a large amount of acid, wash the filter residue 3 times with 500g of water each time, dehydrate, and obtain 423.5g of crude nitrated corn flour.

[0124] A pressure-resistant four-necked flask device with a volume of 2000 mL and filled with 450 g of deionized water was half immersed in a high-precision constant temperature reactor, wherein the pressure-resistant four-necked device was equipped with a reflux condenser, 423.5 g of crude nitrated corn flour was added to the deionized water, stirring was started at a rate of 70 rpm, and the high-precision constant temperature reactor was heated to 101° C. After keeping warm for 30 minutes, 60 g of a sodium carbonate solution with a mass fraction of 5.5% was added thereto, and after keeping warm and stirring for 60 minutes, it was filtered, and the filter residue was washed 3 times with 400 mL of water each time. After dehydration, it was dried at 58° C. and a vacuum degree of 512 mmHg for 8 hours to obtain 398.8 g of nitrated corn flour with a nitrogen content of 14.12%, and the yield was 181.273% (98.87% of the theoretical yield).

[0125] The sample was tested for impact sensitivity using a 5kg drop hammer. The characteristic drop height of the sample was 12cm, indicating that the sample had very high impact sensitivity. The friction sensitivity at a 35° swing angle was 80%. The random sampling test showed that the mean square error of nitration of the sample was 1.89, indicating that the sample had good nitration uniformity.

[0126] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing dust-free, smokeless and sulfur-free fireworks material using corn flour as raw material, characterized in that: The following steps are involved: The corn flour and the nitrifying agent are mixed and nitrated to obtain a crude nitrated corn flour product; The crude nitrated corn meal is mixed with water and subjected to a first washing; After the first washing, an alkaline solution is added to the obtained system, and a second washing is performed to obtain nitrated corn flour; The nitrating agent comprises nitric acid, a catalyst and a nitrating protective agent; The mass fraction of the nitric acid is 55-98%; The nitrification protective agent is ammonium nitrate, potassium nitrate, sodium nitrate or sodium nitrite; The catalyst is concentrated sulfuric acid or acetic anhydride, and the mass fraction of the concentrated sulfuric acid is 98%; The mass ratio of the nitric acid to the catalyst is 0.6 to 5.5:1; The mass of the nitrification protective agent is 0.5 to 15% of the mass of the nitric acid; The mass ratio of the corn flour to the nitrifying agent is 1:2-9; The nitrification comprises sequentially performing a first nitrification and a second nitrification; The temperature of the first nitration is 10-25° C., the time is 20-60 min, and the first nitration is carried out under normal pressure; The temperature of the second nitration is 25-30° C., and the time is 20-30 min. The second nitration is carried out under nitrogen and sealed conditions.

2. The method according to claim 1, characterized in that The particle size of the corn flour is 0.2 to 25 μm; The preparation method of the corn flour comprises the following steps: The corn kernels are sequentially subjected to a first drying, a pulverizing, and a second drying to obtain the corn flour; The moisture content of the corn flour is ≤5%; Before the corn flour is mixed with the nitrifying agent, the method further comprises: drying the corn flour at a temperature of 80° C. for a time of 8 to 12 hours.

3. The method according to claim 1, characterized in that The preparation method of the nitrating agent comprises the following steps: first mixing nitric acid and a catalyst to obtain a mixed solution; The mixed solution and the nitration protective agent are mixed for a second time to obtain the nitration agent.

4. The method according to claim 3, characterized in that The temperature of the first mixing is -5 to 0°C, the first mixing is performed under stirring, and the stirring speed is 400 to 600 rpm; The temperature of the second mixing is 5-10° C., and the time is 1-2 hours.

5. The method according to claim 1, characterized in that Mixing corn flour and nitrifying agent comprises: adding corn flour into nitrifying agent, during the process of adding corn flour, the temperature is 10-25° C., and the stirring speed is 150-200 rpm.

6. The method according to claim 1, characterized in that After the nitrification, the method further comprises: filtering and collecting filter residues; washing and dehydrating the filter residues in sequence to obtain crude nitrated corn flour.

7. The method according to claim 1, characterized in that The mass ratio of the crude nitrated corn flour to water is 1:1-2, the rotation speed of the first washing is 50-100 rpm, the temperature is 100-110° C., and the time is 10-50 min.

8. The method according to claim 1, characterized in that The mass fraction of the alkaline solution is 2-6%, the alkali in the alkaline solution is an inorganic alkali, and the inorganic alkali is sodium carbonate or sodium bicarbonate; The mass ratio of the crude nitrated corn flour to the alkaline solution is 1:0.05-0.5; The second washing has a rotation speed of 50-100 rpm, a temperature of 100-110° C., and a time of 30-60 min.

9. The method according to claim 1, characterized in that: After the second washing, the method further includes: filtering the obtained feed liquid and collecting the filter residue; washing, dehydrating and drying the filter residue in sequence to obtain nitrated corn powder; the number of washing times is 3 to 5 times; the drying temperature is 20 to 60° C., the vacuum degree is 125 to 520 mmHg, and the drying time is 8 to 24 hours.

10. Nitrated corn flour obtained by the method according to any one of claims 1 to 9, characterized in that: The nitrified corn powder is dust-free, smoke-free and sulfur-free, and the nitrogen content of the nitrified corn powder is 8-14.12%.