Nitrates, their preparation and properties. Thermal decomposition of nitrates. The use of nitrogen and its compounds. Sodium nitrate: properties, obtaining, application Sodium nitrate obtaining at home
The invention relates to the production of salts of nitric acid. The essence of the method lies in the fact that nitrite-nitrate solutions obtained by absorption of nitrogen oxides with soda or caustic soda are evaporated to a concentration of the sum of salts of 750-900 g/l without separating the solid phase and at a temperature of 70-90 o C are sent for inversion, inversion the gases are diluted with air and returned to the absorption stage, and the contact separation of ammonia to obtain nitrous gases is switched on periodically as sodium nitrite is processed, and sodium nitrate production solutions are processed into a salt product in a known manner, including crystallization and drying of the product. The technical result is that the method allows to obtain sodium nitrate without the production of sodium nitrite, and also to use nitric acid as a donor of nitrogen oxides at the inversion stage instead of the catalytic oxidation of ammonia. 1 z.p. f-ly, 1 ill.
The invention relates to the chemical industry and can be used in enterprises producing salts of nitric acid. A known method for producing sodium nitrate by neutralizing a solution of soda and (or) sodium hydroxide with nitric acid (V.A. Klevke, N.N. Polyakov, L.Z. Arsenyeva. Technology of nitrogen fertilizers. - M.: Goshimizdat, 1956, p. 94, RF patent 2159738 dated December 3, 1999. Method for producing sodium nitrate). The disadvantage of the known methods is the low concentration of sodium nitrate in the production solution (320-360 g/l) and the associated high steam consumption for its concentration before crystallization of the finished product. The closest in technical essence is a method for obtaining sodium nitrate from nitrite-nitrate solutions by inversion of the latter with nitric acid (M.A. Miniovich, V.M. Miniovich. Salts of nitrous acid. - M.: Chemistry, 1997, p. 100-101 ). The disadvantage of this method is the need for simultaneous production of sodium nitrite and the use of expensive platinum catalysts for the conversion of ammonia to nitrogen oxides. The objective of this proposed invention is to develop a method for producing sodium nitrate from nitrite-nitrate solutions without the production of sodium nitrite, the demand for which is of a pronounced seasonal nature, as well as the use of nitric acid to produce nitrogen oxides at the inversion stage instead of the catalytic oxidation of ammonia with atmospheric oxygen. This goal is achieved by the fact that after the stage of ammonia oxidation with air oxygen, cooling of nitrous gases, their absorption with a solution of soda or caustic soda, the nitrite-nitrate solution is evaporated without separating a solid phase to a total of salts of 750-900 g/l and sent for inversion. When the solution is mixed with non-concentrated nitric acid, the well-known reaction proceeds intensively: 3NaNO 2 + 2HNO 3 = 3NaNO 3 + 2NO + H 2 O. maintained in such a way that the acidity of the intermediate production solution was in the range of 30-80 g/l HNO 3 . The resulting nitrogen oxides are blown off in the inversion column with air. Since the inversion is carried out in the presence of an increased concentration of sodium nitrite, the inversion gases are diluted with additional air before entering the absorption stage. At absorption, they are absorbed by the circulating solution containing excess alkalinity in the form of soda or caustic soda. In this case, nitrite and sodium nitrate are again formed. The drawing shows a diagram of the implementation of the method for producing sodium nitrate. The start-up of the technological scheme is carried out in the traditional way: the contact apparatus is ignited at the stage of ammonia conversion, for which gaseous ammonia and air are used. Nitrous gases pass through a waste heat boiler, where they are cooled to 200-220 o C and enter the absorber, irrigated with a circulating nitrite-nitrate solution containing an excess amount of soda or caustic soda. This solution (the amount of salts is 320-400 g/l) is periodically taken for evaporation, where by evaporation the amount of salts (NaNO 2 + NaNO 3 + Na 2 CO 3) is increased to 750-900 g/l. The temperature of the stripped off solution is maintained within the range of 70-90 o To prevent precipitation of the solid phase. This solution is sent to the inversion column-continuous reactor, which simultaneously dosed non-concentrated nitric acid containing 56-58 wt.% HNO 3 . The ratio of flows of nitric acid and a solution of nitrite-nitrate salts is selected in such a way that an acidic environment is maintained in the column and the intermediate production solution has an acidity of 30-80 g/l HNO 3 . Air is continuously supplied to the reactor, which, in addition to improving the mixing of the reagents, ensures the removal of nitrous gases from the reaction zone. An intermediate acidic solution of sodium nitrate is sent to the neutralizer, where it is neutralized by mixing with a solution of soda or caustic soda to pH 8-10. The inverted nitrous gases are diluted with additional air and sent to the absorption column. After the accumulation of a certain amount of nitrite-nitrate solutions, the contact department is stopped, and the production of sodium nitrate continues due to inversion nitrous gases. In this case, as can be seen from the above reaction, nitric acid serves as a nitric oxide donor, and the process continues as long as the reducing agent, sodium nitrite, is present in the system. With the development of sodium nitrite and a decrease in the concentration of nitrous gases, it becomes necessary to connect the contact oxidation of ammonia. The resulting production solution of sodium nitrate is processed into a salt product according to known way by evaporation, crystallization and separation of sodium nitrate, followed by drying. The circulating mother liquors after the accumulation of impurities (Cl-ions) in them are used in the process of conversion production of potassium nitrate from potassium chloride.
Claim
1. A method for producing sodium nitrate, including the oxidation of ammonia with atmospheric oxygen, cooling of nitrous gases, their absorption with a solution of soda or caustic soda, evaporation of the resulting nitrite-nitrate solutions, inversion of sodium nitrite with nitric acid at a temperature of 70-90 o C with the return of inversion gases to the stage absorption, neutralization of the intermediate solution of sodium nitrate, evaporation, crystallization and drying of the finished product, characterized in that the nitrite-nitrate solutions stripped off to a concentration of the sum of salts of 750-900 g/l are directed to inversion and the acidity of the intermediate solution is maintained at 30-80 g/l HNO 3 , and the inversion gases are diluted with air before returning to the absorption stage. 2. The method according to claim 1, characterized in that the stage of ammonia oxidation is switched on periodically as sodium nitrite is worked out on inversion and the concentration of inversion nitrous gases decreases.
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The invention relates to the field of disposal of components of liquid rocket fuels, in particular the processing of special nitro mixtures, which are the oxidizer of rocket fuel, into fertilizers and salts
The invention relates to a method for producing alkali metal nitrate and alkali metal phosphate in the same technological process from phosphate raw materials and nitrate raw materials, including the following steps: a) interaction of phosphate raw materials with nitrate raw materials to form an aqueous nitrophosphate reaction mixture, followed by optional separation of solid b) introducing an aqueous nitrophosphate reaction mixture into a first ion exchange step, carried out in the presence of a cation exchange resin saturated with alkali metal ions, to exchange the cations present in the reaction mixture for alkali metal ions present in this resin, to obtain an ion-rich stream alkali metal, c) carrying out the first crystallization of the stream obtained in step (b), under conditions that ensure the crystallization of alkali metal nitrate, and separating the crystallized alkali metal nitrate from the mother liquor, d) introducing the mother liquor formed in step (c) into a second ion exchange step, carried out in the presence of an alkali metal-saturated cation exchange resin, to exchange the cations present in the mother liquor for alkali metal ions present in the resin to obtain a phosphate-containing stream enriched in alkali metal ions, and e) carrying out second crystallization of the stream obtained in step (d), under conditions that ensure the crystallization of the alkali metal phosphate, and the separation of the crystallized alkali metal phosphate from the mother liquor
The invention relates to the production of salts of nitric acid
Chemistry is a fascinating science. Those who are interested not only in theory, but also try their skills in practice, know exactly what in question. Every student is familiar with most of the elements from the periodic table. But did everyone manage to try on their own experience mixing reagents and conducting chemical tests? Even today not all modern schools the necessary equipment and reagents are available, therefore chemistry remains a science open to self-study. Many seek to know it deeper by doing research at home.
Not a single do-it-yourselfer can do without nitric acid - an extremely important thing in the household. It is difficult to get the substance: it can only be purchased in a specialized store, where the purchase is carried out according to documents confirming the peaceful use of the substance. Therefore, if you are a homemade master, you most likely will not be able to get this component. Here the question arises of how to make nitric acid at home. The process does not seem to be complicated, however, the output should be a substance of a sufficient level of purity and the required concentration. Here, one cannot do without the skills of an experimental chemist.
Where is the substance used?
The use of nitric acid is reasonable for safe purposes. The substance is used in such areas of human activity:
- creation of coloring pigments;
- development of photographic films;
- preparation of medicines;
- recycling of plastic products;
- use in chemistry;
- fertilizer for horticultural and horticultural crops;
- production of dynamite.
Pure nitric acid, unchanged, looks like a liquid substance, which, on contact with air, begins to release white vapors. It freezes already at -42 o C, and boils at +80 o C. How to remove such a substance as nitric acid with your own hands at home?
Method 1
A fuming substance is obtained by exposing the concentrate to sodium (potassium) nitrate (sodium (potassium) nitrate). As a result of the reaction, the desired substance and sodium (potassium) hydrosulfate are obtained. The reaction scheme looks like this: NaNO 3 + H 2 SO 4 => HNO 3 + NaHSO 4. Remember that the concentration of the resulting substance depends on before entering into the reaction.
Method 2
Obtaining nitric acid at home with a lower concentration of the substance occurs in the same way, it is only necessary to replace sodium nitrate with ammonium nitrate. The chemical equation looks like this: NH 4 NO 3 + H 2 SO 4 =>(NH4) 2 SO 4 + HNO 3 . Note that ammonium nitrate is more affordable than potassium or sodium nitrate, because most researchers conduct reactions based on it.
The higher the H 2 SO 4 concentration, the more concentrated the nitric acid will be. To obtain a balanced substance, it is required to increase the volume of electrolyte required for the reaction. To achieve the desired result, in practice they use the evaporation method, which consists in a gradual decrease in the electrolyte volume by about 4 times from the original one.
Features of the evaporation method
Sifted sand is poured onto the bottom of the dishes and a reservoir with electrolyte is placed. In this case, the process of boiling a gas stove, succumbing or reducing the fire. The process is lengthy, so patience is important in this matter. Experts recommend using boiling water - glass or ceramic tubes designed for chemical experiments, including evaporation. They neutralize the formation of bubbles and reduce the force of boiling, preventing splashing of the substance. Under such conditions, it is permissible to obtain nitric acid at home with a concentration of about 93%.
Tools and reagents for the practical preparation of a substance
For the reaction to take place, you will need:
- concentrated H 2 SO 4 (> 95%) - 50 ml;
- ammonium nitrate, potassium, sodium;
- 100 ml capacity;
- 1000 ml container;
- glass funnel;
- gum;
- water bath;
- crushed ice (can be replaced with snow or cold water);
- thermometer.
Obtaining nitric acid at home, like carrying out any other chemical reaction requires the following precautions:
- In the process of obtaining nitric acid at home, it is necessary to maintain a temperature within 60-70 ° C. If these limits are exceeded, the acid will begin to decompose.
- Vapors and gases may be released during the reaction, therefore, when working with acids, be sure to use a protective mask. Hands must be protected from sudden contact with the skin, so chemists work in rubber gloves. In large chemical industries, where a person comes into contact with substances hazardous to health, workers generally work in special protective suits.
Now you know how to get nitric acid in a simple reaction. Be careful when using such a substance and use it only for peaceful purposes.
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Getting nitrous oxide at home
Laughing gas can be obtained in several ways. The most accessible at home is the G. Davy method - thermal decomposition of ammonium nitrate (ammonium nitrate) according to the reaction:
NH 4 NO 3 \u003d N 2 O + 2H 2 O.
In laboratory conditions, it is more convenient to heat sulfamic acid with nitric acid:
NH 2 SO 2 OH + HNO 3 (73%) = N 2 O + H 2 SO 4 + H 2 O.
However, sulfamic and nitric acids are more difficult to obtain, so we will focus on the decomposition of ammonium nitrate. By the way, the decomposition of ammonium nitrate is used for the synthesis of nitrous oxide on an industrial scale.
When ammonium nitrate is heated, several reactions take place. Here are excerpts from the book L.I. Bagal Chemistry and Technology initiators explosives (1975)
Ammonium nitrate, when heated slightly above the melting point (dry ammonium nitrate melts at 169.6°C), decomposes by the reaction
NH 4 NO 3 NH 3 + HNO 3 (1)
<...>
The reaction of decomposition to nitrous oxide and water was studied by Berthelot, Thomsen and Weley. The first two researchers found the reaction to be exothermic
NH 4 NO 3 => N 2 O + 2H 2 O + 8.8 kcal (2)
The main decomposition reactions of ammonium nitrate at temperatures up to 270°C are (1) and (2). Molten ammonium nitrate, when heated above 250-260 ° C, can release nitrogen oxides, nitrogen and water:
NH 4 NO 3 \u003d\u003e 0.5N 2 + NO + 2H 2 O
4NH 4 NO 3 => 3N 2 + N 2 O 4 + 8H 2 O
3NH 4 NO 3 => 2N 2 + N 2 O 3 + 6H 2 O
Saunders (1922), based on the results of gas analysis, came to the conclusion that the main decomposition reactions at temperatures up to 260 ° C are (1) and (2), as well as the reaction
5NH 3 + 3HNO 3 => 4N 2 + 9H 2 O
Decomposition during an explosion, in his opinion, proceeds by the reaction
8NH 4 NO 3 => 16H 2 O + 2NO 2 + 4NO + 5N 2
<...>
For the normal process of formation of nitrous oxide by decomposition of ammonium nitrate, its temperature regime and degree of purity are of exceptional importance.
As can be seen from the above data, when heated to 240-250 ° C, ammonium nitrate decomposes with the formation of nitrous oxide and water, however, even at this temperature, the resulting "raw" gas contains nitric acid vapor, nitrogen oxides NO and NO 2, ammonia, chlorine (due to impurities of chlorides), nitrogen and "fog" of sublimated ammonium nitrate. It is clear that such a mixture cannot be inhaled (if the thought arises to repeat Davy's experiments), since this deadly! Moreover, if the flask is closed with a rubber stopper, then even after a short-term use it is gradually destroyed (with the formation of completely harmless products).
Therefore, the method of obtaining laughing gas by heating ammonium nitrate in a pan (which is often recommended by "gurus" to laugh at "profanes") looks like black humor at best.
Let's move on to the installation. Ammonium nitrate is decomposed in a Wurtz flask with gentle heating. It is better to use a thermometer, but you can do without it if necessary. As experience has shown, it is better to use heating up to about 220 ° C, while a slight "boiling" of the melt is observed. The resulting "raw gas" for purification is first passed through an ice-cooled trap to collect distilled water mixed with nitric acid. Next, the gas passes through a Drexel flask with a solution of iron sulfate, it also serves as a kind of indicator of the rate of gas release. Then the gas is washed in an impromptu washer (with a porous atomizer) with a solution of 5-7% alkali (sodium or potassium hydroxide), where it is purified from NO 2, nitric acid, chlorine. And, finally, in the third porous atomizer washer, into which a solution of iron (II) sulfate is poured, nitrous oxide is purified from NO and traces of remaining impurities. After it, the gas contains nitrous oxide with some water and nitrogen, as well as traces of NO 2 and NO.
It should be remembered that the purification of nitrous oxide, if it is used to repeat Davy's experiments, should be given Special attention otherwise the gas will be toxic.
Ammonium nitrate (ammonium nitrate) fertilizer was used as a reaction load.
Nitrites and nitrates differ not only in name, in their formula they also have different elements. However, there is something that they have in common. The scope of these substances is quite wide. They are also present in the human body, and if they accumulate too much, a person gets severe poisoning, which can even lead to death.
What are nitrates
Simply put, nitrates are salts of nitric acid. In their formula, they contain a single-digit anion. It used to be called nitrate. Now this is the name of minerals, as well as fertilizers used in agriculture.
Nitrates are obtained with the help of nitric acid, which acts on metals, oxides, salts and hydroxides. All nitrates can be diluted in water. In the solid state, they are strong oxidizing agents, but their properties disappear if nitric acid is added to the solution.
Nitrates retain their properties at ordinary temperatures, but melt at low temperatures, and up to the very complete decomposition. The process of obtaining these substances is very complex, so it will be of interest, perhaps, only to chemists.
Nitrates are the basis for explosives - these are ammonites and other substances. They are mainly used as mineral fertilizers. Now there is no secret that plants use nitrogen from salt to build their cells. The plant creates chlorophyll by which it lives. But in the human body, nitrates become nitrites, which can bring a person to the grave.
Nitrites are also salts
Nitrites are also salts of nitric acid, but with a different formula in their chemical composition. Sodium, calcium nitrites are known. Also known are nitrites of lead, silver, alkali, alkaline earth, 3D metals.
This crystalline substances, which are also inherent in potassium or barium. Some substances dissolve well in water, while others, such as silver, mercury or copper nitrite, are poorly soluble in it. It is noteworthy that nitrites also practically do not dissolve in organic solvents. But if you increase the temperature, the solubility of nitrites improves.
Mankind uses nitrites in the production of nitrogen dyes, to obtain caprolactam, and also as oxidizing and reducing reagents in the rubber, textile and metalworking industries. For example, sodium nitrite is a good preservative and is used in the production of concrete mixes as a hardening accelerator and antifreeze additive.
Nitrites are a poison to human hemoglobin, so they need to be removed from the body daily. They fall into human body either directly or with any other substances. If the human body functions normally, the necessary amount of the substance remains, and the unnecessary is removed. But if a person is sick, there is a problem with nitrite poisoning.
Saltpeter is called nitrate salts (nitrates) of ammonium, sodium, calcium and potassium. They are mainly used in agriculture, as mineral fertilizers, and in the industrial production of pyrotechnics and explosives.
Potassium nitrate is considered a very valuable fertilizer, since it simultaneously contains two substances important for plant life - nitrogen and potassium. But, at the same time, potassium nitrate is the basis of black powder and is simply indispensable in the manufacture of various pyrotechnics. However, the experiments of home-grown craftsmen to create rockets, smokers and other “explosives” often end very badly. Therefore, the sale of potassium nitrate has recently been limited, and with the onset of spring, summer residents are increasingly forced to think about how to make saltpeter on their own. Our advice is intended for amateur gardeners who use potassium nitrate exclusively for peaceful purposes.
How to make potassium nitrate
- Purchase potassium carbonate, aka potash, and ammonium nitrate at the hardware store.
- Dissolve them separately in warm water, preferably distilled. Use equal parts by weight of the reagents. Mix both solutions in an unnecessary container, pouring the potash solution into the ammonium nitrate solution.
- Put the pot on a slow fire. The pan should be large enough, as the mixture foams and expands during the reaction. Stir the mixture regularly. Soon, ammonia gas with a sharp characteristic odor will begin to be released from it - this means that the reaction has begun. Due to the pungent smell of gas, the process is best carried out outdoors or in a room with good ventilation.
- After the evolution of gas stops, remove the pan from the heat and leave in a cool place for a day. After that, large needle-like crystals of potassium nitrate are formed at the bottom, which can only be removed by draining the liquid and dried.
Ammonium nitrate is one of the most common fertilizers; it is applied when sowing almost all crops, both cereals and vegetables, and is also used as a top dressing for adult plants. In mining, ammonium nitrate is widely used as the main component of high explosives - ammonal, ammonite or ammotol. Ammonium nitrate is sold in all hardware stores in the Fertilizers section, where it can be easily purchased. Making ammonium nitrate in artisanal conditions is extremely dangerous and completely unprofitable! You can try to synthesize it yourself only in small doses, observing all safety rules, for educational purposes.
How to make ammonium nitrate
- In the hardware store you need to buy: ammonia, copper sulfate, calcium nitrate.
- Mix ammonia with copper sulphate until you get blue color solution. As a result of the substitution reaction, we will get copper hydroxide, which precipitated, and ammonium sulfate, which remains in solution.
- Drain the ammonium sulfate solution from the sediment and mix it with calcium nitrate. As a result, we get calcium sulfate in the form of a precipitate and a solution containing our ammonium nitrate.
We have described the main ways to obtain saltpeter, and what can be made from saltpeter produced at home is up to you.
