A method of processing nitrate solution production of rare, non-ferrous metals and other chemical industries

 

(57) Abstract:

A method of processing nitrate solutions includes thermal processing and oparka solutions. Oparka solutions perform to achieve a concentration that is close to the boundary of the saturation of this solution at a given temperature. After that, heat treatment is completed in the nozzle of the furnace by burning in her gaseous hydrocarbon fuel in excess air to maintain depending on the form of nitrate solution temperature in the range from 400 to 900oC. the solution is sprayed in the form of bulk torch in the upper part of the furnace towards the upward flow of the combustion gas obtained by thermal decomposition of nitrates powdery finished product drop-down on the oven hearth, and gaseous products at the outlet of the furnace, which before release to the atmosphere purified from dust and water absorption. The method allows to obtain valuable products that can be returned into circulation and widely applied in other areas. 3 C.p. f-crystals.

The invention relates to the field of processing of nitrate solutions formed during the production of rare and nonferrous metals in the hydrometallurgical processing of V, formed and other chemical industries.

It is well known that processing of nitrate solutions is a complex task. This is because the nitrate ion is not formed with cations of any metal and insoluble compounds and cannot after precipitation and separation from solution to tackledirect in the tailings pond, because all nitrates of metals, including basic, worse or better soluble in water. At the same time, the nitrate ions are toxic to the environment and human and solutions containing them cannot be disposed of in the drainage network and the environment.

Currently, the only radical method of processing nitrate solutions is their heat treatment, consisting in Parke nitrate solutions to dry salt used in other sectors of the chemical industry or in agriculture as chemical fertilizers (see, for example, M. E. Posin. "Technology of mineral salts". Volume II. Leningrad, publishing house "Chemistry", 1974, S. 1218-1221). Evaporation of solutions of sodium nitrate is carried out in a two-circuit vacuum evaporation installation. It receives a suspension, in which the content of NaNO3is about 75%. In the solution steriti of the evaporator serves to screw the mold with a shirt, in which when cooled from 90-93oC to 40-45oC there is a further crystallization of salt. Crystals NaNO3separated from the solution in a centrifuge and dried in a tumble dryer. The mother liquor from the centrifuge is attached to the original solution directed to evaporation.

This method, like all other methods of heat treatment of nitrate solutions parcoy allow to process them to obtain dry nitrate salts. However, receives parcoy salt is heavily polluted by impurities contained in the solutions. They are mostly very hygroscopic, which makes them packing, storage, transport and subsequent use in industry. The use of nitrate as nitrogen fertilizer in agriculture, in recent times, started to decline sharply, because it has been proven that it is more suitable for plant nutrition nitrogen as ammonium compounds, and not nitrate salts. Additionally, the method of parki time-consuming and quite complex in hardware design.

The present invention was based on the objective to develop a method of processing nitrate solution production of rare refractory metals and other Protea technical result - obtaining valuable products that can be returned into circulation in the metallurgical industry and is widely used in other areas of chemical production, which increases the value of the method.

The technical result is achieved in that in the method of processing nitrate solution production of rare, non-ferrous metals and other chemical production by thermal processing, including oparka solutions according to the invention oparka solutions perform to achieve a concentration that is close to the boundary of the saturation of this solution at a given temperature, and then heat treatment is completed in the nozzle of the furnace by burning in her gaseous hydrocarbon fuel in excess air to maintain depending on the form of nitrate solution temperature in the range from 400 to 900oC, at which the solution of the dispersion in three-dimensional plume in the upper part of the furnace towards the upward flow of the combustion gas obtained by thermal decomposition of nitrates poroshkoobraznogo finished product drop-down on the oven hearth, and gaseous products at the outlet of the furnace, which before release to the atmosphere purified from dust and water absorption.

New is also that the heat treatment of solutions of nitrates of metals having a normal electrode potential of less than - 2,34, in thermal decomposition receive a metal oxide, which interacts with carbon dioxide gaseous products form a powdered metal carbonates, falling on under the furnace, the gaseous products receive oxygen and nitrogen.

This solution thus obtained metal carbonates are finely dispersed structure, which is particularly valuable for many industries and technologies.

New as well is the fact that during the heat treatment of metal nitrates, having a normal electrode potential from -2,34 V to +0,3448 In, in thermal decomposition receive powdered metal oxides, falling on the furnace bottom and the gaseous products receive oxygen and nitrogen oxides, which result from the absorption of water is allow have a fine structure, what is particularly valuable for some of the chemical industries and technologies. The resulting nitric acid in chemical metallurgy can go right back into circulation or find a wide application in various fields of chemical production.

Also new is the fact that during the heat treatment of metal nitrates, having a normal electrode potential of more than +0,3448 In, in thermal decomposition receive powdered metals fall on the furnace bottom and the gaseous products receive oxygen and nitrogen oxides, which result from the absorption of water to form subconsciously solution of nitric acid.

This solution get fine powdered metals having special value in certain fields of science and technology. The resulting nitric acid in chemical metallurgy can go right back into circulation or find a wide application in various fields of chemical production.

The inventive method of processing nitrate solution production of rare, non-ferrous metals and other chemical production is performed in the following way. At the initial stage, oparka neither is of this solution at a given temperature. It should be borne in mind that the saturation condition is the concentration of this salt, which is equal to the solubility of this salt in water at a given temperature. A saturated solution is necessarily in equilibrium with the solid phase, i.e., in a saturated solution is necessarily present crystalline salt. In other words oparka is carried out until the maximum concentration of a solution in which the solution is still not formed a crystalline salt, but the solution is close to it. One stripped off to such a state nitrate solution is further subjected to the final stage of heat treatment - combustion in spray pyrolysis furnace. Spray pyrolysis furnace heated flue gases resulting from the combustion of natural gas or other hydrocarbons, such as propane-butane mixture or fuel oil. One stripped off until the above condition nitrate solution is sprayed into the upper part of the furnace through a thin nozzle spray pattern in the form of bulk torch. Hot flue gases with temperatures ranging from 400 to 900oC containing carbon dioxide in large quantities, rise countercurrent up and interact with the torch finely powdered nitrate solution. Droplets of solutions and Nitra is moisture, drying, thermal dissociation of nitrates, recrystallization, the interaction of the formed products from the flue gases, and so on, resulting in the formation of gaseous and solid products of combustion. The choice of the lower and upper limits of the temperature of the flue gases due to the following reasons. At temperatures below 400oC will not achieve complete and rapid decomposition of the nitrates of all metals. At temperatures above 900oC possible melting or thermal decomposition of the formed solid powdered products that fall on the furnace bottom, which is unacceptable.

Gaseous products consisting mainly of nitrogen, oxygen, oxides of nitrogen and carbon dioxide are discharged from the upper part of the furnace and exposed to dust control, cooling, absorption of water, sanitary cleaning of oxides of nitrogen, after which discharged into the atmosphere.

The solid products of combustion, with a powdery appearance, rolled on under the furnace and discharged from it as a finished product.

As was established by the authors of all the nitrates of the metals in the final product of thermal dissociation, can be divided into three groups.

In these group metals are in accordance with and alkaline earth metals from lithium, having a standard electrode potential E0=-3,01 In to barium, with E0=-2,90 Century

The second group includes metals from magnesium, having a standard electrode potential E0=-2,34 In to copper, inclusive, with E0=+0,3448 Century

The third group includes metals from silver, with E0=+0,7995 In, and up.

During thermal dissociation of the nitrates of the metals of the first group of oxides of the metal, elemental nitrogen and oxygen. The resulting oxides of metals of the first group further interact with carbon dioxide from the flue gases to obtain powdered metal carbonate, which fall on the furnace floor. While carbonates of Li, Cs, Na, K, Ca, Sr, Ba is stable at temperatures 600-1400oC. the Obtained powdery carbonates depending on quality can directly be used in various branches of chemical production.

During thermal dissociation of the nitrates of the metals of the second group oxides of metals that fall on the furnace bottom, oxides of nitrogen and oxygen.

During thermal dissociation of nitrate third group is formed of powdered metal, drop down on the oven hearth, oxides of nitrogen and oxygen.

oC), or not formed (Al, Fe, Cr).

In accordance with the scheme of thermal dissociation of the nitrates of the metals of the first group, the second and third groups and organized recycling the gaseous products of combustion before it is discharged into the atmosphere.

Combustion of the nitrates of the first group flue gases are cleaned from dust, cool and carry out sanitary water from oxides of nitrogen, because burn nitrates almost always have a mixture of nitrates of other metals of the second group.

Combustion of the nitrates of the metals of the second and third groups flue gases are cleaned from dust, cooled and then they contain nitrogen oxides absorb water to form a solution of nitric acid of low concentration, which can immediately be returned in this production.

Below, the inventive method is confirmed by specific examples of its implementation in the processing of nitrate solutions of different metals.

Example 1. Took nitrate solution sodium NaNO3. Carried out his oparka under vacuum at a temperature of t = 80oC to a concentration of 600 g/l, close to the saturation state when this temperaturte fuel. While nitrate solution was siphoned off towards the upward flow of the combustion gases, the temperature of which is maintained within 500oC. thus proceeded following the total chemical reaction

< / BR>
As a result of processing the received pure powdered sodium carbonate - soda ash. Soda ash is widely used in technology of rare and nonferrous metals, glass, building materials, inorganic chemistry in the manufacture of sodium salts, soap and leather industries. In the atmosphere after wet and dry cleaning dropped atomic nitrogen, oxygen and excess of carbon dioxide.

Example 2.

Took a solution of potassium nitrate KNO3. Carried out his oparka under vacuum at a temperature of t = 80oC to a concentration of about 300 g/l, close to the saturation state at a given temperature. After that, he made a final heat treatment in the furnace of pyrolysis when burning natural gas fuel. While nitrate solution was siphoned off towards the upward flow of the combustion gases, the temperature of which is maintained within 500oC. thus proceeded following the total chemical reaction is the result of processing of the received pure powdered potassium carbonate potash, which can be used, for example in the manufacture of explosives, glass, catalysts, and as a complex fertilizer. In the atmosphere after wet and dry cleaning dropped atomic nitrogen, oxygen and excess of carbon dioxide.

Example 3. Took nitrate solution calcium Ca(NO3)2. Carried out his oparka under vacuum at a temperature of t=80oC to a concentration of 400 g/l, close to the saturation state at a given temperature. After that, he made a final heat treatment in the furnace of pyrolysis when burning natural gas fuel. While nitrate solution was rasilimali towards the upward flow of the combustion gases, the temperature of which is maintained within 900oC. thus proceeded following the total chemical reaction

Ca(NO3)2---> CaO + N2+ O2< / BR>
CaO + CO2---> CaCO3< / BR>
As a result of processing the received pure powdered calcium carbonate - chalk, which can be used in various fields of industry and construction. In the atmosphere after wet and dry cleaning dropped atomic nitrogen, oxygen and excess of carbon dioxide.

Example 4.

Took nitrate rustie about 300 g/l, close to the saturation state at a given temperature. After that, he made a final heat treatment in the furnace of pyrolysis when burning natural gas fuel. While nitrate solution was rasilimali towards the upward flow of the combustion gases, the temperature of which was maintained in the range 400oC. thus proceeded following the total chemical reaction

Mg(NO3)2---> MgO + NO2+ O2< / BR>
3NO2+ H2O ---> 2HNO3+ NO

As a result of processing the received pure powdered magnesium oxide, which can be used, for example in the chemical industry. In the exhaust gas contains nitrogen oxides, which result from the absorption of water to form subconsciously solution of nitric acid. Received weak nitric acid can be used in chemical metallurgy, for example at the opening of loparite concentrate in other areas of chemical production. In the atmosphere after cleaning reset oxygen, nitrogen and carbon dioxide.

Example 5.

Took a nitrate solution of lanthanum La(NO3)3. Carried out his oparka under vacuum at a temperature of t = 80oC to a concentration of about 400 is the processing in the pyrolysis furnace by burning natural gas fuel. While nitrate solution was rasilimali towards the upward flow of the combustion gases, the temperature of which was maintained in the range 600oC. thus proceeded following the total chemical reaction

2La(NO3)3---> La2O3+ 6NO2+ O2< / BR>
As a result of processing the received pure powdered oxide of lanthanum, which can be used, for example in the optical industry for the production of coated optics. In the exhaust gas contains nitrogen oxides, which result from the absorption of water to form subconsciously solution of nitric acid. Received weak nitric acid can be used in chemical metallurgy, for example at the opening of loparite concentrate in other areas of chemical production. In the atmosphere after cleaning reset oxygen, nitrogen and carbon dioxide.

Example 6.

Took nitrate solution silver AgNO3. Carried out his oparka under vacuum at a temperature of t = 80oC to a concentration of 400 g/l, close to the saturation state at a given temperature. After that, he made a final heat treatment in the furnace of pyrolysis combustion gas prirodnih which supported within 600oC. thus proceeded following the total chemical reaction

2AgNO3---> 2Ag + 2NO2+ O2< / BR>
As a result of processing the obtained powdery silver - mobile, which can be used, for example in the electrical industry. In the exhaust gas contains nitrogen oxides, which result from the absorption of water to form subconsciously solution of nitric acid. Received weak nitric acid can be used in chemical metallurgy, for example at the opening of loparite concentrate in other areas of chemical production. In the atmosphere after sanitary schistki reset oxygen and nitric oxide.

From the specific embodiments of the claimed invention for any specialist in this field are obvious possibilities for its realization with the simultaneous solution of the set task. It is also obvious that the invention can be made small changes, but which will not exceed the scope of the invention defined by the following claims.

The inventive method of processing nitrate solution production of rare, non-ferrous metals and drugadvisorvia) nitrate ion in nitrate solutions, waste production. At the same time ensures the powdered products that are valuable reagents for chemical metallurgy and various fields of chemical production. In the processing of many nitrate solutions along the way turns out to nitric acid, which is widely used in many fields of technology. All this makes the inventive method of processing nitrate solutions are particularly valuable and versatile.

1. A method of processing nitrate solutions by thermal processing, including oparka solutions, characterized in that oparka solutions perform to achieve a concentration that is close to the boundary of the saturation of this solution with the subsequent completion of the heat treatment in the nozzle of the furnace by burning in her gaseous hydrocarbon fuel in excess air to maintain depending on the form of nitrate solution temperature in the range from 400 to 900oC, at which the solution is sprayed in the form of bulk torch in the upper part of the furnace towards the upward flow of the combustion gas obtained by thermal decomposition of nitrates powdery finished product drop-down on the furnace bottom, and gazoo and water.

2. The method according to p. 1, characterized in that the heat treatment of solutions of nitrates of metals having a normal electrode potential of less than -2,34 In, in thermal decomposition receive powdered metal carbonates, falling on the furnace bottom and the gaseous products receive oxygen and nitrogen.

3. The method according to p. 1, characterized in that the heat treatment of solutions of nitrates of metals having a normal electrode potential of less than -2,34 V to +0,3448 In, in thermal decomposition receive powdered metal oxides, falling on the furnace bottom and the gaseous products receive oxygen and nitrogen oxides, which result from the absorption of water to form subconsciously solution of nitric acid.

4. The method according to p. 1, characterized in that the heat treatment of solutions of nitrates of metals having a normal electrode potential of more than +0,3448 In, in thermal decomposition receive powdered metals fall on the furnace bottom and the gaseous products receive oxygen and nitrogen oxides, which result from the absorption of water to form subconsciously solution of nitric acid.

 

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