Nitrate production method

Abstract

The invention relates to the field of chemical manufacturing methods, and discloses a nitrate manufacturing method, which comprises a nitric acid dilution stage, a neutralization reaction stage, an evaporation stage, a crystallization stage, a crushing stage, a centrifugal separation stage, a blanking stage, a packaging stage, a waste gas treatment stage, an oxidation reduction stage, a discharge stage and an acid dilution stage, selecting a container capable of bearing the corrosion of nitric acid, ensuring that the container is clean and free of impurities, and respectively pouring a proper amount of water and nitric acid into the prepared container; a dilute nitric acid dripping method is adopted, the reaction intensity of metal and dilute nitric acid can be controlled, nitric oxide generated when the metal reacts with the dilute nitric acid can be reduced through the dilute nitric acid dripping at a constant speed, and therefore the treatment pressure of the spray tower is reduced, and the spray tower can adopt clear water to intercept nitric oxide in waste gas; a reducer and a catalyst are matched to realize reduction of part of nitrogen oxides, so that the repeated utilization rate of dilute nitric acid is increased, and the production cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of chemical manufacturing methods, in particular to a nitrate manufacturing method. Background Art

[0002] The existing preparation processes of nitrates mainly include oxidation method, nitric acid method, evaporation method and bioconversion method. Among them, the oxidation method is to oxidize ammonia into nitrous acid, and then further oxidize it into nitric acid, and finally combine it with metal cations to form nitrates; In the existing nitrate manufacturing process through oxidation, the metal reactant is directly mixed and soaked with dilute nitric acid to obtain a nitrate solution. However, the reaction is violent during the reaction. Since a large amount of nitrogen oxides will be generated when nitric acid and metal react, the nitrogen oxide treatment device at the tail will be under very high pressure when the reaction is violent, which will cause huge pressure on the exhaust gas treatment equipment at the end, which may easily lead to the discharge of nitrogen oxides into the air due to insufficient treatment capacity of the exhaust gas treatment equipment, thereby causing environmental pollution. In addition, the existing method for treating nitrogen oxides is to use a spray tower to spray alkali solution (sodium hydroxide solution) in the spray tower to neutralize and absorb nitrogen oxides, but this will cause secondary pollution. Although the alkali solution can absorb nitrogen oxides, sodium nitrate will be formed (nitrogen oxides react with water to form nitric acid and sodium hydroxide to form sodium nitrate), and the treatment process of sodium nitrate is complicated and costly. At the same time, nitrogen oxides are generated quickly, in large quantities, and the process is intermittent, so it is impossible to use clean water spray plus catalyst redox method, and the reuse rate of nitric acid cannot be effectively improved. Summary of the invention

[0003] The object of the present invention is to provide a method for producing nitrates, which can effectively solve the problems in the background technology.

[0004] To achieve the above object, the technical solution adopted by the present invention is: The nitrate manufacturing method comprises a nitric acid dilution stage, a neutralization reaction stage, an evaporation stage, a crystallization stage, a crushing stage, a centrifugal separation stage, a feeding stage, and a packaging stage. After the neutralization reaction stage, there are also an exhaust gas treatment stage, an oxidation-reduction stage, and a discharge stage.

[0005] As a further preferred embodiment of the present invention, the following steps are included: S1. During the nitric acid dilution stage, select a container that can withstand the corrosion of nitric acid and ensure that it is clean and free of impurities. Pour appropriate amounts of water and nitric acid into the prepared containers respectively. Slowly pour the nitric acid into the water while gently stirring with a glass rod to evenly dissipate the heat. Always pour water into the acid rather than the other way around to avoid violent reactions. Continue stirring until the nitric acid is completely dissolved and mixed evenly, and set aside.

[0006] S2, neutralization reaction stage, clean the reactor to ensure that its interior is clean and free of impurities, then safely transfer the required metal into the reactor, and then seal the reactor to ensure that there is no gas or liquid leakage during the experiment. Subsequently, heat the reactor to make the temperature inside the reactor reach a level suitable for the reaction of the metal with dilute nitric acid. When the temperature inside the reactor reaches a predetermined value, start to slowly add dilute nitric acid to the reactor. It is necessary to pay attention to controlling the dropping speed to avoid excessive reaction. Dilute nitric acid reacts with the metal in the reactor to generate nitrates. During this process, the temperature in the reactor needs to be kept stable to ensure that the reaction proceeds fully.

[0007] S2.1. In the waste gas treatment stage, the metal in the reactor reacts with the dilute nitric acid solution to produce a certain amount of nitrogen oxides, and the waste gas containing nitrogen oxides is discharged into the spray tower through the reactor. By spraying clean water in the spray tower, most of the nitrogen oxides are intercepted and absorbed, thereby forming dilute nitric acid. The dilute nitric acid in the spray tower can be collected and reused.

[0008] S2.2, in the oxidation-reduction stage, after the exhaust gas containing nitrogen oxides is treated by a spray tower, the exhausted exhaust gas will still contain a small amount of nitrogen oxides. At this time, the exhaust gas discharged through the spray tower is introduced into the reducer. Then, the exhaust gas entering the reducer cooperates with the catalyst to undergo oxidation-reduction reaction, thereby reducing nitrogen monoxide and nitrogen dioxide into nitrogen and then discharging them.

[0009] S3, evaporation stage, after the nitrate melt is obtained in the reactor, the nitrate solution is introduced into the concentration reactor through a pipeline, so as to evaporate the water in the nitrate melt to reach the required concentration.

[0010] S5. Crystallization. After obtaining the nitrate solution of the required concentration, the nitrate solution is pumped into the crystallizer. Since the interior of the crystallizer is usually designed to be in a vacuum state, the solution will flash, that is, the solvent evaporates rapidly, causing the solution to quickly reach an oversaturated state. As the solvent continues to evaporate, the concentration of nitrate gradually increases until it reaches the saturation point. At this time, nitrate molecules begin to aggregate with each other to form tiny crystal nuclei. The crystal nuclei continue to grow in the solution, gradually become larger, and form visible crystal particles. After the nitrate melt in the crystallizer is completely crystallized, its crystals are discharged.

[0011] S6. Crushing. The crusher is arranged above the centrifugal separation equipment, and the crystallizer is arranged above the crusher. A filter bag is arranged in the centrifuge, that is, the nitrate crystals in the crystallizer directly fall into the crusher after being discharged, so that the nitrate crystals are crushed by the crusher, and the crushed nitrate crystals directly fall into the filter bag in the centrifuge. When the nitrate crystals in the filter bag are temporarily stored to a set weight, the water contained in the nitrate can be dehydrated by the centrifuge.

[0012] S7, unloading. After the nitrate crystals are dehydrated by the centrifuge, the filter bag containing the nitrate crystals is hoisted into the automatic weighing device by the hoisting equipment, and the unloading weight is pre-set on the automatic weighing device.

[0013] S8. Packaging: a packaging mechanism is arranged below the automatic metering device, that is, the automatic metering device releases a set weight of nitrate crystals at a time, thereby completing the packaging of the nitrate crystals.

[0014] As a further preferred embodiment of the present invention, an electric dropper can be selected for the droplet dripping in the neutralization reaction stage.

[0015] As a further preferred embodiment of the present invention, the filter bag is a polytetrafluoroethylene filter bag.

[0016] Compared with the prior art, the present invention has the following beneficial effects: In the present invention, the dilute nitric acid dripping method is adopted to control the reaction intensity of the metal and the dilute nitric acid, and the nitrogen oxides generated when the metal reacts can be reduced by the uniform dripping of the dilute nitric acid, thereby reducing the processing pressure of the spray tower, and the spray tower can use clean water to intercept the nitrogen oxides in the exhaust gas, and cooperate with the reducer and the catalyst to achieve the reduction of part of the nitrogen oxides, thereby improving the reuse rate of the dilute nitric acid and reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0018] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0019] like Figure 1 As shown, the nitrate manufacturing method provided by the present invention includes a nitric acid dilution stage, a neutralization reaction stage, an evaporation stage, a crystallization stage, a crushing stage, a centrifugal separation stage, a feeding stage, and a packaging stage. After the neutralization reaction stage, there are also an exhaust gas treatment stage, an oxidation-reduction stage, and a discharge stage.

[0020] The following steps are involved: First, during the nitric acid dilution stage, select a container that can withstand the corrosion of nitric acid and make sure it is clean and free of impurities. Pour appropriate amounts of water and nitric acid into the prepared containers respectively. Slowly pour the nitric acid into the water while gently stirring with a glass rod to dissipate the heat evenly. Always pour water into the acid rather than the other way around to avoid violent reactions. Continue stirring until the nitric acid is completely dissolved and mixed evenly. Set aside.

[0021] During the neutralization reaction stage, clean the reactor to ensure that its interior is clean and free of impurities. Then, transfer the required metal to the reactor safely. Then, seal the reactor to ensure that there will be no gas or liquid leakage during the experiment. Subsequently, heat the reactor to make the temperature inside the reactor reach a level suitable for the reaction of the metal with dilute nitric acid. When the temperature inside the reactor reaches the predetermined value, slowly add dilute nitric acid to the reactor. An electric dropper can be used for the droplet in the neutralization reaction stage. It is necessary to control the droplet speed to avoid excessive reaction. Dilute nitric acid reacts with the metal in the reactor to generate nitrates. During this process, the temperature inside the reactor needs to be kept stable to ensure that the reaction proceeds fully and the waste gas During the treatment stage, the metal in the reactor reacts with the dilute nitric acid solution to produce a certain amount of nitrogen oxides, and the waste gas containing nitrogen oxides is discharged into the spray tower through the reactor, and most of the nitrogen oxides are intercepted and absorbed by spraying clean water in the spray tower, thereby forming dilute nitric acid, and the dilute nitric acid in the spray tower can be collected and reused. In the oxidation-reduction stage, after the waste gas containing nitrogen oxides is treated by the spray tower, the discharged waste gas will still contain a small amount of nitrogen oxides. At this time, the waste gas discharged through the spray tower is introduced into the reducer, and the waste gas entering the reducer is combined with the catalyst for oxidation-reduction reaction, thereby reducing nitric oxide and nitrogen dioxide to nitrogen and then discharged.

[0022] In the evaporation stage, after the nitrate melt is obtained in the reactor, the nitrate melt is introduced into the concentration reactor through a pipeline, so that the water in the nitrate melt can be evaporated to reach the required concentration.

[0023] During the crystallization stage, after obtaining the nitrate solution of the required concentration, the nitrate solution is pumped into the crystallizer. Since the interior of the crystallizer is usually designed to be in a vacuum state, the solution will flash, that is, the solvent evaporates rapidly, causing the solution to quickly reach an oversaturated state. As the solvent continues to evaporate, the concentration of nitrate gradually increases until it reaches the saturation point. At this time, nitrate molecules begin to aggregate with each other to form tiny crystal nuclei. The crystal nuclei continue to grow in the solution, gradually becoming larger and forming visible crystal particles. After the nitrate melt in the crystallizer is completely crystallized, its crystals are discharged.

[0024] In the crushing stage, the crusher is arranged above the centrifugal separation equipment, and the crystallizer is arranged above the crusher. A filter bag is arranged in the centrifuge, that is, the nitrate crystals in the crystallizer fall directly into the crusher after being discharged, so that the nitrate crystals are crushed by the crusher, and the crushed nitrate crystals fall directly into the filter bag in the centrifuge. The filter bag adopts a polytetrafluoroethylene filter bag. When the nitrate crystals in the filter bag are temporarily stored to a set weight, the water contained in the nitrate can be dehydrated by the centrifuge. In the feeding stage, after the nitrate crystals are dehydrated by the centrifuge, the filter bag containing the nitrate crystals is hoisted into the automatic meter by a hoisting device, and the automatic meter pre-sets the feeding weight. In the packaging stage, a packaging mechanism is arranged below the automatic meter, that is, the automatic meter releases a set weight of nitrate crystals at a time, thereby completing the packaging of the nitrate crystals.

[0025] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for producing nitrates, characterized in that: The process comprises a nitric acid dilution stage, a neutralization reaction stage, an evaporation stage, a crystallization stage, a crushing stage, a centrifugal separation stage, a feeding stage and a packaging stage. After the neutralization reaction stage, an exhaust gas treatment stage, an oxidation-reduction stage and a discharge stage are also arranged.

2. The method for producing nitrate according to claim 1, characterized in that: The following steps are involved: S1. Nitric acid dilution stage: select a container that can withstand nitric acid corrosion and ensure that it is clean and free of impurities. Pour appropriate amounts of water and nitric acid into the prepared containers respectively. Slowly pour the nitric acid into the water while gently stirring with a glass rod to evenly dissipate the heat. Continue stirring until the nitric acid is completely dissolved and mixed evenly. Set aside. S2, neutralization reaction stage, clean the reactor to ensure that the inside is clean and free of impurities, then safely transfer the required metal into the reactor, and then seal the reactor to ensure that there is no gas or liquid leakage during the experiment, then heat the reactor to make the temperature in the reactor reach a level suitable for the reaction of the metal with dilute nitric acid, when the temperature in the reactor reaches a predetermined value, slowly add dilute nitric acid into the reactor, and the dilute nitric acid reacts with the metal in the reactor to generate nitrate; S2.1, in the waste gas treatment stage, the metal in the reactor reacts with the dilute nitric acid solution to produce a certain amount of nitrogen oxides, and the waste gas containing nitrogen oxides is discharged into the spray tower through the reactor, and most of the nitrogen oxides are intercepted and absorbed by the spray of clean water in the spray tower, thereby forming dilute nitric acid, and the dilute nitric acid in the spray tower can be collected and reused; S2.2, oxidation-reduction stage, after the exhaust gas containing nitrogen oxides is treated by the spray tower, the exhaust gas discharged will still contain a small amount of nitrogen oxides. At this time, the exhaust gas discharged by the spray tower is introduced into the reducer. Then, the exhaust gas entering the reducer cooperates with the catalyst to undergo oxidation-reduction reaction, thereby reducing nitrogen monoxide and nitrogen dioxide into nitrogen gas for emission; S3, evaporation stage, after the nitrate melt is obtained in the reactor, the nitrate solution is introduced into the concentration reactor through a pipeline, so as to evaporate the water in the nitrate melt to reach the required concentration; S5, crystallization. After obtaining the nitrate solution of the required concentration, the nitrate solution is pumped into the crystallizer. Since the interior of the crystallizer is usually designed to be in a vacuum state, the solution will flash, that is, the solvent evaporates rapidly, causing the solution to quickly reach a supersaturated state. As the solvent continues to evaporate, the concentration of nitrate gradually increases until it reaches the saturation point. At this time, the nitrate molecules begin to aggregate with each other to form tiny crystal nuclei. The crystal nuclei continue to grow in the solution, gradually become larger, and form visible crystal particles. After the nitrate melt in the crystallizer is completely crystallized, its crystals are discharged; S6, crushing, the crusher is arranged above the centrifugal separation equipment, and the crystallizer is arranged above the crusher, the centrifuge is provided with a filter bag, that is, the nitrate crystals in the crystallizer are discharged and directly fall into the crusher, so that the nitrate crystals are crushed by the crusher, and the crushed nitrate crystals directly fall into the filter bag in the centrifuge, when the nitrate crystals in the filter bag are temporarily stored to a set weight, the water contained in the nitrate can be dehydrated by the centrifuge; S7, unloading, after the nitrate crystals are dehydrated by the centrifuge, the filter bag containing the nitrate crystals is hoisted into the automatic weighing device by the hoisting equipment, and the unloading weight is pre-set in the automatic weighing device; S8. Packaging: a packaging mechanism is arranged below the automatic metering device, that is, the automatic metering device releases a set weight of nitrate crystals at a time, thereby completing the packaging of the nitrate crystals.

3. The method for producing nitrate according to claim 1, characterized in that: An electric dropper can be selected for the droplet during the neutralization reaction stage.

4. The method for producing nitrate according to claim 1, characterized in that: The filter bag is a polytetrafluoroethylene filter bag.

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