Preparation process of silver nitrate

Abstract

The invention relates to the technical field of silver nitrate, and discloses a preparation process of silver nitrate, which comprises the following steps: performing first oxidation reaction on silver, nitric acid and hydrogen peroxide at normal temperature and normal pressure; after charging is completed in the first oxidation reaction and the temperature is stable, raising the temperature to 88-92 DEG C, and carrying out a second oxidation reaction; carrying out heat preservation on the reaction liquid of the second oxidation reaction at 88-92 DEG C for 4.5-6 hours, and carrying out a third oxidation reaction; adding silver oxide into the reaction liquid of the third oxidation reaction, mixing and stirring, and standing to obtain a precipitate and a supernatant liquid; and evaporating and concentrating the supernatant, and cooling and crystallizing to obtain silver nitrate crystals. The preparation process of the silver nitrate is simple to operate, the prepared silver nitrate is high in purity and yield and low in nitrogen oxide content, the production benefit is effectively improved, and the environmental protection pressure is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of silver nitrate, and in particular to a preparation process of silver nitrate. Background Art

[0002] Silver nitrate is a colorless crystal that is easily soluble in water, ammonia, glycerol, and slightly soluble in ethanol. Under certain conditions, such as when exposed to light, this colorless crystal will be reduced to pure silver. In the air, silver nitrate easily absorbs moisture and decomposes slightly. In addition, pure silver nitrate is stable to light, but due to the purity of general products, its aqueous solution and solid are often stored in brown reagent bottles to prevent decomposition.

[0003] In terms of chemical properties, silver nitrate exhibits strong oxidizing properties, which enables it to play a key role in certain reactions. For example, it can react with chloride ions to form a white precipitate, so it is often used to detect the chloride ion content in water samples; at the same time, silver nitrate can also react with other acids and salts to prepare other silver salts, such as silver chloride and silver bromide.

[0004] Silver nitrate has a wide range of uses. In the field of photography, it is an important component of photosensitive materials and is used to make movie films, X-ray negatives and photographic films. In the electroplating industry, silver nitrate is used for silver plating of electronic components and other crafts, and is also widely used as a silver plating material for mirrors and thermos flasks. In addition, it is used in the inorganic industry to make other silver salts, and in the electronics industry to make conductive adhesives, new gas purifiers, A8x molecular sieves, silver-plated pressure-equalizing suits and gloves for live working. At the same time, silver nitrate is also used in the medical field. For example, it is used in medicine to corrode hyperplastic granulation tissue, and its dilute solution can be used as a bactericidal agent for eye infections.

[0005] At present, the preparation process of silver nitrate is to react nitric acid with silver metal to produce silver nitrate and nitric oxide gas. However, this method uses a large amount of nitric acid, and nitric acid is a strong oxidizing agent with high corrosiveness, which has extremely high requirements for equipment and pipelines. At the same time, it is not stable enough and is prone to produce a large amount of toxic gases, which poses safety and environmental hazards. In addition, during the preparation process, the reaction temperature is high and the reaction is strong, which makes the yield of the prepared silver nitrate low and the production cost high.

[0006] Therefore, it is urgent to provide a preparation process in which silver nitrate is of good quality and high yield. Summary of the invention

[0007] In order to solve at least one of the above technical problems and develop a preparation process of silver nitrate with good quality and high yield, the present application provides a preparation process of silver nitrate.

[0008] On the one hand, the present application provides a process for preparing silver nitrate, comprising the following steps: S1. At room temperature and pressure, silver, nitric acid and hydrogen peroxide undergo a first oxidation reaction. The reaction formula of the first oxidation reaction is as follows: 2Ag+2HNO3+H2O2→2AgNO3+2H2O; S2. After the first oxidation reaction is completed and the temperature is stable, the temperature is raised to 88-92°C to carry out the second oxidation reaction. The reaction formula of the second oxidation reaction is as follows: Ag+2HNO3→AgNO3+H2O+NO2; S3, the reaction liquid of the second oxidation reaction is kept at 88-92°C for 4.5-6h, and a third oxidation reaction is carried out. The reaction formula of the third oxidation reaction is as follows: 3Ag+4HNO3→3AgNO3+2H2O+NO; S4, adding silver oxide to the reaction solution of the third oxidation reaction, mixing and stirring, and then standing to obtain a precipitate and a supernatant; S5. Take the supernatant, evaporate and concentrate it, cool and crystallize it to obtain silver nitrate crystals.

[0009] By adopting the above technical scheme, the preparation process of silver nitrate of the present application is simple to operate, and the prepared silver nitrate has high purity and yield, which effectively improves production efficiency and reduces environmental pressure.

[0010] The first oxidation reaction of the present application is carried out at room temperature, which effectively reduces the reaction risk and energy consumption, and avoids the violent reaction between hydrogen peroxide and nitric acid at a high temperature, which releases a large amount of heat and causes the system temperature to rise rapidly, thereby inducing accidents such as uncontrolled reaction and splashing, and produces excessive nitrogen oxides, which affects the quality of the silver nitrate product.

[0011] The present invention increases the temperature after the first oxidation reaction to carry out the second oxidation reaction and maintains the temperature for a period of time at a specific temperature to carry out the third oxidation reaction, so as to make the reaction more complete and further improve the reaction efficiency and the yield of silver nitrate.

[0012] Optionally, in S1, silver and water are added into a reactor at normal temperature and pressure, and then nitric acid and hydrogen peroxide are added to cause a first oxidation reaction.

[0013] Optionally, in S1, the dripping flow rate of nitric acid is 85-150 kg / h.

[0014] Optionally, in S1, hydrogen peroxide is added dropwise every 5 minutes, and the rate of each addition is 30-50 kg / h.

[0015] Optionally, in S1, the time for each dropwise addition of the hydrogen peroxide is 0.5-1 min.

[0016] By adopting the above technical solution, the nitric acid and hydrogen peroxide of the present application adopt a specific flow process, which helps to control the reaction rate and temperature, avoid excessive flow added at one time, excessive local concentration, and excessively violent reaction, which is not conducive to the stability and safety of the reaction process.

[0017] Optionally, in S2, the weight of nitric acid is 1-1.2 times the weight of silver; the weight of hydrogen peroxide is 20-25wt% of the weight of silver.

[0018] Optionally, the weight ratio of silver to water is 14-18:1.

[0019] Optionally, the concentration of the nitric acid is 63-68wt%; the concentration of the hydrogen peroxide is 45-55wt%.

[0020] Optionally, in S3, the heating rate is 0.3-0.6°C / min.

[0021] Optionally, in S5, the standing time is 4.5-5.5h.

[0022] In summary, the present invention includes at least one of the following beneficial technical effects: 1. The preparation process of silver nitrate of the present application is simple to operate, and the prepared silver nitrate has high purity and yield, which effectively improves production efficiency and reduces environmental pressure; 2. The first oxidation reaction of the present application is carried out at room temperature, which effectively reduces the reaction risk and energy consumption, and avoids the violent reaction of hydrogen peroxide and nitric acid at a high temperature, which releases a large amount of heat and causes the system temperature to rise rapidly, thereby inducing accidents such as uncontrolled reaction and splashing, and produces excessive nitrogen oxides, which affects the quality of silver nitrate products; 3. The nitric acid and hydrogen peroxide in the present application adopt a specific flow process, which helps to control the reaction rate and temperature, avoid excessive flow added at one time, excessive local concentration, and excessively violent reaction, which is not conducive to the stability and safety of the reaction process; 4. The present application raises the temperature after the first oxidation reaction to carry out the second oxidation reaction and keeps the temperature at a specific temperature for a period of time to carry out the third oxidation reaction, so that the reaction is more complete, further improving the reaction efficiency and the yield of silver nitrate. DETAILED DESCRIPTION

[0023] Glossary Normal temperature and pressure: 25℃, 101kPa.

[0024] The present application is further described in detail below with reference to the embodiments.

[0025] The present invention provides a process for preparing silver nitrate, comprising the following steps: S1. At room temperature and pressure, silver, nitric acid and hydrogen peroxide undergo a first oxidation reaction. The reaction formula of the first oxidation reaction is as follows: 2Ag+2HNO3+H2O2→2AgNO3+2H2O; S2. After the first oxidation reaction is completed and the temperature is stable, the temperature is raised to 88-92°C to carry out the second oxidation reaction. The reaction formula of the second oxidation reaction is as follows: Ag+2HNO3→AgNO3+H2O+NO2; S3, the reaction liquid of the second oxidation reaction is kept at 88-92°C for 4.5-6h, and a third oxidation reaction is carried out. The reaction formula of the third oxidation reaction is as follows: 3Ag+4HNO3→3AgNO3+2H2O+NO; S4, adding silver oxide to the reaction solution of the third oxidation reaction, mixing and stirring, and then standing to obtain a precipitate and a supernatant; S5. Take the supernatant, evaporate and concentrate it, cool and crystallize it to obtain silver nitrate crystals. Specific embodiments

[0026] The raw material models of this application are as follows. Unless otherwise specified, the raw materials of this application are all commercially available: Silver: National Standard No. 1 silver ingot; Silver oxide: CAS number, 1301-96-8.

[0027] Test items and methods: Silver nitrate purity and impurity content: tested in accordance with the standard of "GBT670-2007 Chemical Reagent Silver Nitrate"; Silver nitrate yield: the ratio of the actual mass of silver nitrate obtained by inputting metallic silver to the theoretical mass of silver nitrate.

[0028] Examples 1-3 Example 1 A preparation process of silver nitrate comprises the following steps: S1, take 800.4kg silver ingot and put it into the reactor, then add 57.2kg deionized water; S2. At room temperature and pressure, 800.4 kg of nitric acid with a concentration of 63 wt% is added to the reactor at a flow rate of 85 kg / h, and 160 kg of hydrogen peroxide with a concentration of 55 wt% is added dropwise to the reactor to perform a first oxidation reaction, wherein the reaction formula of the first oxidation reaction is as follows: 2Ag+2HNO3+H2O2→2AgNO3+2H2O; S3. After the first oxidation reaction is completed and the temperature is stable, the temperature is raised to 88°C at a heating rate of 0.3°C / min to perform a second oxidation reaction; wherein the reaction formula of the second oxidation reaction is as follows: Ag+2HNO3→AgNO3+H2O+NO2; S4, keeping the reaction liquid of the second oxidation reaction at 88° C. for 6 hours, and performing a third oxidation reaction; the reaction formula of the third oxidation reaction is as follows: 3Ag+4HNO3→3AgNO3+2H2O+NO; S5, mixing the material after the third oxidation reaction with 3.3 kg of silver oxide, stirring and standing for 4.5 hours to obtain a precipitate and a supernatant; S6, taking the supernatant, evaporating and concentrating it, cooling and crystallizing it, and obtaining silver nitrate crystals; In S2, hydrogen peroxide was added dropwise every 5 minutes, the rate of each addition was 30 kg / h, and the time of each addition was 0.5 minutes.

[0029] Example 2 A preparation process of silver nitrate comprises the following steps: S1, take 800.4kg of silver ingot and put it into the reactor, then add 50.4kg of deionized water; S2. At room temperature and pressure, 886.4 kg of nitric acid with a concentration of 65 wt% is added to the reactor at a flow rate of 85 kg / h, and 184 kg of hydrogen peroxide with a concentration of 50 wt% is added dropwise to the reactor to perform a first oxidation reaction, wherein the reaction formula of the first oxidation reaction is as follows: 2Ag+2HNO3+H2O2→2AgNO32H2O; S3, after the first oxidation reaction is completed and the temperature is stabilized at 60°C, the temperature is raised to 90°C at a heating rate of 0.5°C / min to carry out a second oxidation reaction; wherein the reaction formula of the second oxidation reaction is as follows: Ag+2HNO3→AgNO3+H2O+NO2; S4, keeping the reaction liquid of the second oxidation reaction at 90° C. for 5 hours, and performing a third oxidation reaction; the reaction formula of the third oxidation reaction is as follows: 3Ag+4HNO3→3AgNO3+2H2O+NO; S5, mixing the material after the third oxidation reaction with 3.3 kg of silver oxide and stirring, and then standing for 5 hours to obtain a precipitate and a supernatant; S6, taking the supernatant, evaporating and concentrating it, cooling and crystallizing it, and obtaining silver nitrate crystals; Wherein, in S2, hydrogen peroxide is added dropwise every 5 minutes, the rate of each addition is 30 kg / h, and the time of each addition is 0.5 minutes.

[0030] Example 3 A preparation process of silver nitrate comprises the following steps: S1, take 800.4kg silver ingot and put it into the reactor, then add 44.5kg deionized water; S2. At room temperature and pressure, 960.5 kg of nitric acid with a concentration of 68 wt% is added to the reactor at a flow rate of 85 kg / h, and 200.1 kg of hydrogen peroxide with a concentration of 45 wt% is added dropwise to the reactor to perform a first oxidation reaction, wherein the reaction formula of the first oxidation reaction is as follows: 2Ag+2HNO3+H2O2→2AgNO3+2H2O; S3. After the first oxidation reaction is completed and the temperature is stable, the temperature is raised to 92° C. at a heating rate of 0.6° C. / min to perform a second oxidation reaction; wherein the reaction formula of the second oxidation reaction is as follows: Ag+2HNO3→AgNO3+H2O+NO2; S4, keeping the reaction liquid of the second oxidation reaction at 92° C. for 4.5 hours, and performing a third oxidation reaction; the reaction formula of the third oxidation reaction is as follows: 3Ag+4HNO3→3AgNO3+2H2O+NO; S5, mixing the material after the third oxidation reaction with 3.3 kg of silver oxide and stirring, and then standing for 5.5 hours to obtain a precipitate and a supernatant; S6, taking the supernatant, evaporating and concentrating it, cooling and crystallizing it, and obtaining silver nitrate crystals; Wherein, in S2, hydrogen peroxide is added dropwise every 5 minutes, the rate of each addition is 30 kg / h, and the time of each addition is 0.5 minutes.

[0031] Comparative Example 1 Based on Example 2, except for the different method of adding nitric acid in S2, the other steps are consistent with Example 2; wherein, the method of adding nitric acid is: at normal temperature and pressure, 886.4 kg of nitric acid with a concentration of 65 wt % is added to the reactor at one time.

[0032] Comparative Example 2 Based on Example 2, except for the different method of adding hydrogen peroxide in S2, the other steps are consistent with Example 2; wherein, the method of adding hydrogen peroxide is as follows: at room temperature and pressure, 886.4 kg of nitric acid with a concentration of 65 wt % is added to the reactor at a flow rate of 85 kg / h, and at the same time, 184 kg of hydrogen peroxide with a concentration of 50 wt % is added to the reactor at one time.

[0033] Comparative Example 3 Based on Example 2, except that in S3, after the first oxidation reaction is completed and the temperature is stable, the temperature is raised to 80° C. at a heating rate of 0.5° C. / min to carry out the second oxidation reaction, the remaining steps are consistent with Example 2.

[0034] Comparative Example 4 Based on Example 2, except that in S3, after the first oxidation reaction is completed and the temperature is stable, the temperature is raised to 95°C at a heating rate of 0.5°C / min to carry out the second oxidation reaction, the remaining steps are consistent with Example 2.

[0035] Comparative Example 5 Based on Example 2, except for the different reaction temperature in S2, the remaining steps are consistent with Example 2; wherein, S2: controlling the temperature of the reactor to 45° C., adding 886.4 kg of nitric acid with a concentration of 65 wt % to the reactor at a flow rate of 85 kg / h, and at the same time, adding 184 kg of hydrogen peroxide with a concentration of 50 wt % to the reactor dropwise to carry out a first oxidation reaction, wherein the hydrogen peroxide is added dropwise once every 5 min, the rate of each addition is 30 kg / h, and the time of each addition is 0.5 min.

[0036] The nitrates prepared in Examples 1-3 and Comparative Examples 1-5 were tested for performance. The test results are shown in Table 1.

[0037] Table 1 It can be seen from Examples 1-3, Comparative Examples 1-5 and Table 1 that the silver nitrate prepared by the specific silver nitrate preparation process in the present application meets the national priority standard, and the yield of the prepared silver nitrate is high; It can be seen from Comparative Examples 1-2, Example 2 and Table 1 that the present application adopts a specific feeding process to gradually add nitric acid and hydrogen peroxide into the reactor, which helps to control the reaction rate and temperature, effectively improve the quality of the silver nitrate product, and increase the yield of silver nitrate, thereby increasing production revenue; It can be seen from Comparative Examples 3-4, Example 2 and Table 1 that the second oxidation reaction of the present application is more conducive to the reaction at a specific temperature and improves the comprehensive performance of silver nitrate; It can be seen from Comparative Example 5, Example 2 and Table 1 that the first oxidation reaction of the present application is carried out at room temperature and pressure, which effectively reduces the reaction risk and avoids the violent reaction of hydrogen peroxide and nitric acid at a high temperature, which releases a large amount of heat, affects the quality of the silver nitrate product, and reduces the yield.

[0038] Embodiment 4-7 Based on Example 2, except that the flow rate of nitric acid in S2 is different, the remaining steps are consistent with Example 2.

[0039] Example 4 In S2, the flow rate of nitric acid is 92 kg / h.

[0040] Example 5 In S2, the flow rate of nitric acid is 108 kg / h.

[0041] Example 6 In S2, the flow rate of nitric acid is 125 kg / h.

[0042] Example 7 In S2, the flow rate of nitric acid is 150 kg / h.

[0043] Embodiment 8-9 Based on Example 5, except for the different dropping rate of hydrogen peroxide in S2, the remaining steps are consistent with Example 5.

[0044] Example 8 Hydrogen peroxide was added dropwise every 5 minutes, at a rate of 40 kg / h and for 0.5 minutes.

[0045] Example 9 Hydrogen peroxide was added dropwise every 5 minutes, at a rate of 50 kg / h and for 0.5 minutes.

[0046] Embodiment 10-11 Based on Example 8, except for the different time of adding hydrogen peroxide, the other steps are the same as Example 8.

[0047] Example 10 Hydrogen peroxide was added dropwise every 5 minutes, with a rate of 40 kg / h and a duration of 0.8 minutes.

[0048] Embodiment 11 Hydrogen peroxide was added dropwise every 5 minutes, at a rate of 40 kg / h and for 1 minute.

[0049] The performance of the silver nitrate prepared in Examples 4-11 was tested, and the test results are shown in Table 2.

[0050] Table 2 It can be seen from Examples 4-7, 2 and Table 2 that the specific flow rate of nitric acid used in S2 of the present application is more conducive to promoting the effective progress of the oxidation reaction and improving the comprehensive performance of silver nitrate; It can be seen from Examples 8-11, 5 and Table 2 that the specific flow rate of hydrogen peroxide used in S2 of the present application makes the comprehensive performance of the prepared silver nitrate more excellent.

[0051] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, all equivalent changes made according to the principles of the present application should be included in the protection scope of the present application.

Claims

1. A process for preparing silver nitrate, characterized in that, The following steps are involved: S1. At room temperature and pressure, silver, nitric acid and hydrogen peroxide undergo a first oxidation reaction. The reaction formula of the first oxidation reaction is as follows: 2Ag+2HNO3+H2O2→2AgNO3+2H2O; S2. After the first oxidation reaction is completed and the temperature is stable, the temperature is raised to 88-92°C to carry out the second oxidation reaction. The reaction formula of the second oxidation reaction is as follows: Ag+2HNO3→AgNO3+H2O+NO2; S3, the reaction liquid of the second oxidation reaction is kept at 88-92°C for 4.5-6h, and a third oxidation reaction is carried out. The reaction formula of the third oxidation reaction is as follows: 3Ag+4HNO3→3AgNO3+2H2O+NO; S4, adding silver oxide to the reaction solution of the third oxidation reaction, mixing and stirring, and then standing to obtain a precipitate and a supernatant; S5. Take the supernatant, evaporate and concentrate it, cool and crystallize it to obtain silver nitrate crystals.

2. A process for preparing silver nitrate according to claim 1, characterized in that, In S1, silver and water are added into a reactor at normal temperature and pressure, and then nitric acid and hydrogen peroxide are added to cause a first oxidation reaction.

3. A process for preparing silver nitrate according to claim 1, characterized in that, In the S1, the dripping flow rate of nitric acid is 85-150 kg / h.

4. A process for preparing silver nitrate according to claim 1, characterized in that, In S1, hydrogen peroxide is added dropwise every 5 minutes, and the rate of each addition is 30-50 kg / h.

5. A process for preparing silver nitrate according to claim 4, characterized in that, The time for each dropwise addition of the hydrogen peroxide is 0.5-1 min.

6. A process for preparing silver nitrate according to claim 1, characterized in that, In S1, the weight of nitric acid is 1-1.2 times the weight of silver; the weight of hydrogen peroxide is 20-25wt% of the weight of silver.

7. A process for preparing silver nitrate according to claim 2, characterized in that, The weight ratio of silver to water is 14-18:

1.

8. A process for preparing silver nitrate according to claim 1, characterized in that, The concentration of the nitric acid is 63-68wt%; the concentration of the hydrogen peroxide is 45-55wt%.

9. A process for preparing silver nitrate according to claim 1, characterized in that: In S2, the heating rate is 0.3-0.6°C / min.

10. A process for preparing silver nitrate according to claim 1, characterized in that: In S4, the standing time is 4.5-5.5h.

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