Method for extracting nitric acid from solution and deactivating urea nitrate sediment

FIELD: recovery of liquid radioactive wastes.

SUBSTANCE: method for extracting nitric acid from solution includes bringing solution in contact with nitrogen-containing agent and separating the phases. For the process use is made of organic nitrogen-containing material forming poorly soluble sediment together with nitric acid. Urea nitrate sediment deactivating method includes treatment of inert nozzle in fluidized bed at temperature of 750 - 800 °C with fuel combustion products having residual oxygen content of 2 - 3 volume percent.

EFFECT: reduced cost.

7 cl, 5 ex

 

The present invention relates to the field of purification of nitric acid extraction of refined water and tailings solutions of technological schemes of refining uranium for the nuclear industry.

Neutralization extraction of refined difficult high (up to 3-4 mol/l) concentration of nitric acid. Using the traditional method of wastewater treatment and chemical neutralization (Supplement milk of lime, caustic soda, ammonia and so on) resets to the tailing dump huge amounts of nitrates due to the high solubility of most nitrate salts. To prevent discharge of nitrates prior to neutralization extraction refined to remove nitric acid.

Known method of recovery of nitric acid from effluents from the nuclear industry [RF Patent №2179761, MKI7G 21 F 9/04, G 21 F 9/06, publ. 20.02.2002].

The essence of the method consists in the instantaneous thermal decomposition of nitrate ions in solution and vapor recovery of oxides of nitrogen by cooling and absorption in water with the formation of nitric acid.

The disadvantages of the method are the need for fine spraying waste water, which is associated with the completeness of the process, and the high cost of energy for evaporation of water and heating gases to the working temperature, and the necessity is clean nitric acid from impurities of radionuclides, which are present in the wastewater enterprises of the nuclear industry.

The closest in technical essence is the method of separation of nitric acid from a solution containing the acid and nitrosamine aromatic compound [RF Patent №2061671, MKI6C 07 C 201/16, 201/06, publ. BI No. 16, 10.06.1996].

The essence of the method consists in bringing a solution containing nitric acid, into contact with a nitrogen-containing agent, of at least one molten nitrate salt. Molten nitrate salt is mixed with the acid solution containing nitrosamine connection, whereby when the contacts they form two phases. Polluting solution of nitric acid is converted to the phase of the molten salt. Than provide clean nitrosamines aromatic compounds.

The disadvantages of the method are the need to heat the solution and melt, high consumption of nitrate salts (more than 30 g of salt per 1 g of nitric acid), limited the scope of the method, due to the peculiarities of the composition of the solution in which the components of the solution have different solubility, partial separation of the phases, resulting in contamination of the molten salt impurities contained in the initial solution.

The known method for abatement of nitrate of urea by Razlog the deposits at temperatures above 350° With and transfer in polymer - product of the pyrolysis of urea. [Molodkin A.K., Ellert, GV, O.M. Ivanova, Skotnikov GA // inch, T. 12, s-957 (1967)]. The disadvantage of this method is the gas emission pyrolysis products (nitrogen oxides, ammonia), as well as the need for the collection and recycling of the polymer melt, which requires additional costs.

The technical result of the invention is to reduce costs, extend the scope of application of the method and the full utilization of precipitation.

The invention

The technical result is achieved by the proposed method as a nitrogen-containing agent use organic nitrogen-containing substance called nitric acid soluble precipitate in the organic nitrogen-containing agent use granulated urea with obtaining sediment nitrate urea; nitric acid is removed from solution, containing more than 0.7 mol/l of nitric acid; granular urea added with an excess of 15-20 wt.%. to the stoichiometric amount, and the exposure and separation of the resulting sludge nitrate urea is conducted at a temperature not exceeding 0°; sediment nitrate urea neutralized in the fluidized bed of inert nozzle at a temperature of 750-800° With the products of fuel combustion with residual oxygen content of 2-3% vol.

The use of urea as asado is containing a series of agent allows you to get a solid adduct - nitrate urea (CO(NH2)2·HNO3), in which nitric acid is associated with urea in the poorly soluble compound that does not contain impurities (e.g., heavy and radioactive metals). The formation of solid nitrate of urea facilitates the separation of the phases (sediment nitrate urea and the filtrate), and the absence of impurities further simplifies the handling of sludge.

The use of granulated urea eliminates dilution delaborated solutions, and thereby reducing the efficiency of extraction of nitric acid.

Excess urea - 15-20% wt. to the stoichiometric amount can effectively be extracted from the solution of nitric acid. With less excess urea efficiency of extraction of nitric acid is reduced. The higher the excess does not increase sediment nitrate urea.

Restraint and separation of the resulting sludge nitrate urea is conducted at a temperature not exceeding 0° for more complete extraction of nitric acid from the solution. Further lowering of the solution temperature does not lead to a positive effect. In addition, at temperatures below -10° is the crystallization of a solution of nitrate of urea solution freezes).

The lower concentration limit nitrate solutions from which to extract nitric acid is 0.7 the ol/l of nitric acid, that is determined by the solubility of the nitrate urea nitrate extraction raffinate at a temperature of 0° C.

Disposal of sludge nitrate urea in the fluidized bed of inert nozzle at a temperature of 750-800° With the products of fuel combustion with residual oxygen content of 2-3%. you can destroy the sediment nitrate urea with low yield of nitrogen oxides in the gas emissions.

List of figures and tables

Figure 1 shows the dependence of the residual nitric acid from an excess of urea atand t=0° C; figure 2. depicts the dependence of the residual nitric acid from the temperature atand 20%excess of urea, figure 3 shows the dependence of the degree of extraction of nitric acid from its concentration in the solution; figure 4 shows the dependence of the concentration of uranium in the sediment nitrate urea concentration of uranium in nitric acid extraction raffinate.

Information confirming the possibility of carrying out the invention

The method is illustrated by the following examples.

Example 1. In solutions of nitric acidcontaining 50 mg/l of uranium and having a temperature of t=0° C, with stirring, add granulated urea with an excess of urea from 0.75 to 2.1 over stechiometric is Kim quantity required for interaction with nitric acid. Then the solution was kept at temperature t=0° C, which is required for maturation of precipitation nitrate urea. Department of precipitation is carried out at the same temperature. The filtrates analyzed for the content of nitric acid and uranium. The results obtained for nitric acid are presented in figure 1.

From figure 1 it follows that the lack of urea over the stoichiometric amount (<1) in the filtrate there is a high residual content of nitric acid. With the growth of excess urea (up to 1.15-1.2), the decrease of the residual nitric acid. With an excess of urea (To>1.2) reducing the residual content of nitric acid in the filtrate does not occur. The uranium content in the obtained sediments nitrate urea does not exceed 4· 10-4wt.%.

Thus, an excess of urea over the stoichiometric quantity of 15-20% is optimal for the extraction of nitric acid from nitric acid solution containing uranium.

Example 2. In solutions of nitric acidcontaining 50 mg/l of uranium and having a temperature from -4 to 21° C, with stirring, add granulated urea at 20% excess of urea. Then the solution is maintained at a temperature from -4 to 21° that it is necessary for the maturation of precipitation nitrate urea. Department of adcav performed at the same temperature, as the maturation of sediment. The filtrates analyzed for the content of nitric acid and uranium. The results obtained for nitric acid are presented in figure 2.

From figure 2 it follows that in the temperature range from -4 to 0° With the residual content of nitric acid remains constant. With further increase in temperature to a residual content of nitric acid in the filtrate is growing. The uranium content in the obtained sediments nitrate urea does not exceed 4· 10-4wt.%.

Thus, for optimal recovery of nitric acid from nitric acid solution containing uranium using urea needs to maintain a process temperature not higher than 0° C.

Example 3. In solutions of nitric acidtemperature 0° with stirring, add granulated urea at 20% excess of urea. Then the solution is maintained at a temperature of 0°that it is necessary for the maturation of precipitation nitrate urea. Department of precipitation is carried out at the same temperature as the maturation of sediment. The filtrates analyzed for the content of nitric acid. The results are presented in figure 3.

From figure 3 it follows that the degree of extraction of nitric acid from a solution depends on its initial content. Whenthe degree of extraction of nitric acid is reduced to zero. Therefore clicks the zoom, the lower concentration limit nitrate solutions from which can be derived nitric acid, 0.7 mol/L.

Example 4. In solutions of nitric acidcontaining from 10 to 50 mg/l at 20% excess of urea. Then the solution is maintained at a temperature of 0° that it is necessary for the maturation of precipitation nitrate urea. Department of precipitation is carried out at a temperature of 0° C. the Sediment examined for the content of uranium. The results are presented in figure 4.

From Fig 4. it follows that when extracted using urea nitric acid from a solution containing as an impurity a uranium content of the latter in the sediment nitrate urea does not exceed 4· 10-4wt.%. Low uranium content greatly simplifies the further use of nitrate of urea, for example, as a complex nitrogen fertilizer.

Example 5. Disposal of dry nitrate of urea is carried out in fluidized bed of inert nozzle (γ -Al2About3the grain size 2.0-2.5 mm) in the exhaust gas with the oxygen content of 2-3%. - the products of combustion of fuel. The gas flow is 6.0 m2per hour, the consumption of nitrate of urea - 120 g/hour, the temperature of the gases 750-800° C.

In the products of neutralization of nitrate of urea found to 3.3 g/m3nitric oxide (NOxalthough the complete oxidation of nitrotyrosine should be formed to 23.9 g/m 3NOx. Thus, when the removal of nitrate of urea in the fluidized bed of inert nozzle exit of nitric oxide does not exceed 11-13% wt.

When the temperature of the gases above 800° and the oxygen content in gases more than 2-3%. there has been a sharp increase in the output of nitric oxide. When the oxygen content is less than 2-3%. there is an unstable combustion with a large yield of soot.

Compared with the prototype of the proposed method dramatically - 23 times to reduce the consumption of the reagent with 30 g (nitrate salt) to 1.3 g (urea) per 1 g of nitric acid.

Use as a nitrogen-containing agent is urea, which is a selective reagent with respect to nitric acid, allows the extraction of nitric acid of different solutions, which expands the area of application of the method.

Compared to prototype the use of urea allows to obtain a residue (nitrate urea), which is almost not contaminated with heavy and radioactive metals.

Disposal of sludge nitrate urea in the fluidized bed of inert nozzle at a temperature of 750-800° in gases with the oxygen content of 2-3%. helps to ensure the complete destruction of the sediment with a minimum output of secondary pollutants.

1. The method of extraction of nitric acid from a solution comprising bringing the races is the thief in contact with the nitrogen-containing agent and the separation of the phases, characterized in that as the nitrogen-containing agent use organic nitrogen-containing substance called nitric acid soluble precipitate.

2. The method according to claim 1, characterized in that the organic nitrogen-containing agent use granulated urea with obtaining sediment nitrate urea.

3. The method according to claim 1, characterized in that the nitric acid is removed from solution, containing more than 0.7 mol/l of nitric acid.

4. The method according to claim 2, characterized in that the granulated urea is added with an excess of 15-20 wt.% to the stoichiometric quantity, and the shutter speed and the sludge separation of nitrate of urea is carried out at a temperature not exceeding 0°C.

5. The method of disposal of sludge nitrate urea by decomposition at elevated temperature, characterized in that the precipitated nitrate urea neutralized in the fluidized bed of inert nozzle at a temperature of 750-800°With the products of fuel combustion with residual oxygen content of 2-3%.



 

Same patents:

FIELD: chemical technology; recovery of deactivated and decontaminated radioactive industrial wastes.

SUBSTANCE: proposed method that can be used for deactivating and decontaminating industrial radioactive wastes incorporating Tb-232 and their daughter decay products (Ra-228, Ra-224), as well as rare-earth elements, Fe, Cr, Mn, Sl, Ti, Zr, Nb, Ta, Ca, Mg, Na, K, and the like includes dissolution of wastes, treatment of solutions or pulps with barium chloride, sulfuric acid, and lime milk, and separation of sediment from solution. Lime milk treatment is conducted to pH = 9 - 10 in the amount of 120-150% of total content of metal oxyhydrates stoichiometrically required for precipitation, pulp is filtered, and barium chloride in the amount of 0.4 - 1.8 kg of BaCl2 per 1 kg of CaCl2 contained in source solution or in pulp, as well as pre-diluted sulfuric acid spent 5 - 20 times in chlorine compressors in the amount of 0.5 - 2.5 kg of H2SO4 per 1 kg of BaCl2 are introduced in filtrate. Alternately introduced in sulfate pulp formed in the process are lime milk to pH = 11 - 12, then acid chloride wash effluents from equipment and industrial flats at pulp-to-effluents ratio of 1 : (2 - 3) to pH = 6.5 - 8.5, and pulp obtained is filtered. Decontaminated solution is discharged to sewerage system and sediment of barium and calcium sulfates and iron oxysulfate are mixed up with oxyhydrate sediment formed in source pulp neutralization process; then 35 - 45 mass percent of inert filler, 10 - 20 mass percent of magnesium oxide, and 15 -m 25 mass percent of magnesium chloride are introduced in pasty mixture formed in the process while continuously stirring ingredients. Compound obtained is subjected to heat treatment at temperature of 80 - 120 oC and compressed by applying pressure of 60 to 80 at.

EFFECT: reduced radioactivity of filtrates upon separation of radioactive cakes due to enhanced coprecipitation of natural radionuclides.

7 c, 1 ex

The invention relates to the field of processing of liquid radioactive waste, in particular, to methods of extraction of precious metals
The invention relates to the field of processing of liquid radioactive waste

The invention relates to the field of processing of liquid radioactive waste

The invention relates to the field of chemical technology and can be used in the purification and concentration of toxic solutes, including radioactive high level of activity
The invention relates to the field of disposal of liquid waste, in particular to the disposal of liquid nitric acid waste containing radioactive substances
The invention relates to the field of chemical technology and can be used for neutralization and decontamination of radioactive solutions and waste waters containing Th-232 and child products of disintegration (Ra-228, Ra-224) in excess of established NRB and OSPB, and REE, Sc, Fe, Cr, Mn, Al, Ti, Zr, Nb, Ta, Ca, Mg, Na, K, etc

The invention relates to the field of radiochemical technology, namely the processing of water-tail nitric acid solutions resulting from the reprocessing of irradiated nuclear fuel (SNF) and containing technetium

The invention relates to the processing of uranium-containing solid and/or liquid waste

The invention relates to the field of nuclear energy and can be used for the disposal of alkaline liquid metal coolants

FIELD: sewerage systems, particularly for cleaning waste water from oil.

SUBSTANCE: device includes drain pipe connected with mud trap communicated in turn with oil remover by the first pipe. Oil remover is connected with well by the second pipe. Hose is put on the second pipe inside oil remover and air-filled vessel is attached to hose end.

EFFECT: possibility to clean increased volumes of water, reduced costs.

2 dwg

Electrolyzer // 2252921

FIELD: medical instrument making, namely apparatuses for preparing ecologically safe electrically activated water.

SUBSTANCE: electrolyzer includes two electrodes (one electrode of stainless steel and other electrode of carbon); bridge type voltage rectifier; electric circuit plug; membrane; second doubled membrane - cover, for example of tracing paper or canvas; glass vessel; low-resistance voltage divider with taps; array of light emitting diodes with additional resistors whose number corresponds to that of taps; housing of electrolyzer. Plug is connected with inlets of bridge type voltage rectifier; negative outlet of voltage rectifier is connected with electrode of stainless steel. Second positive-polarity outlet of voltage rectifier is connected through low-resistance voltage divider with taps to carbon electrode arranged in second membrane-cover. All cathode ends of light emitting diodes with additional resistors are connected in parallel and they are connected with positive outlet of voltage rectifier; second ends of said diodes are connected with respective taps of low-resistance voltage divider.

EFFECT: possibility for displaying information concerning activation degree of water at preparing it for medical purposes, preparation of ecologically safe anolyte.

2 dwg

FIELD: equipment for electrochemical activation of drinking and sprinkling water while providing oxidation-reduction properties and biological worth of water.

SUBSTANCE: plant includes diaphragm electrolyzer having vertical cylindrical electrodes, namely tubular cathode and rod anode between which thin-wall tubular porous diaphragm is placed. Inner diameter of hollow cylindrical cathode and diameter of rod anode are set according to next relations: and . Speed value of water movement in cathode chamber is set according to expression where Dc - inner diameter of hollow cylindrical cathode, mm; k - coefficient of matching to dimensions m1/12 x s 1/2 ; k1 - proportionality factor, m -2; Q -maximum efficiency of plant, m3/s; Ho -water pressure before inlet of cathode chamber, m; L - length of cathode chamber, m; Δ1 ≤ 0.004 - gap between inner surface of hollow cylindrical cathode and diaphragm, m; Δ2 ≤ 0.004 -gap between surface of anode and inner surface of diaphragm, m; δ - thickness of diaphragm, m; Vk - water movement speed in cathode chamber, m/s; Dout =(Dc - 2Δ1) -outer diameter of diaphragm, m.

EFFECT: enhanced quality of drinking and sprinkling water and therefore increased productivity of agricultural plants due to optimal oxidation-reduction properties at electrochemical activation.

9 cl, 2 dwg, 1 ex

FIELD: processes for treating water in centralized systems for supplying drinking water, possibly preparation of electrically activated water.

SUBSTANCE: method comprises steps of unipolar treatment of drinking water in flow-through diaphragm-type electrolyzer having separate inlet and outlet at predetermined relation of speeds of catholyte and anolyte flows in range 0.94:1 - 1.50:1 at passing specific quantity of electricity in range 0.071 -0.083 A-hours for 1 l of catholyte and anolyte.

EFFECT: lowered specific consumption of electricity quantity and electric energy.

1 tbl, 1 ex

FIELD: petrochemical industry; heat-and-power engineering; environmental protection.

SUBSTANCE: the invention is pertaining to the field of an environmental protection, in particular, to the methods of sewage purification from petroleum, oil products, greases, lubricants, shale-processing products, and also to the methods of utilization of water treatment and water-gas purification cationic wastes. It may be used in petrochemical industry and heat-and-power engineering. The method of sewage purification provides for filtration through a layer of a granulated sorbent, in the capacity of which they use a waste of water treatment and water-gas purification - cationite, with its consequent separation and use as an additive to a fuel. At that a sorption ability of cationite for oil products makes 0.24-0.27 kg / kg of the sorbent. The method ensures a deep purification of sewage from oil products, an increase of an expected life of the sorption element and production of additional fuel-power resources at the expense of utilization of wastes.

EFFECT: the invention ensures a deep purification of sewage from oil products, an increased service life of the sorption element, production of additional fuel-power resources.

2 cl, 1 tbl, 1 ex

FIELD: heat power engineering.

SUBSTANCE: the invention is pertaining to the field of heat power engineering and may be used in boiler rooms and the thermal power stations. A method of a vacuum deaeration of water, according to which the initial water and the heating agent are fed into a vacuum deaerator and deaerated water is withdrawn from the vacuum deaerator and the flash steam formed in the process of deaeration is removed with the help of a mechanical vacuum pump. Control over operation of the mechanical vacuum pump is performed by a change of the rate of its electric drive rotation speed according to the given value of pH of the deaerated water. The technical effect achievable by the stated invention consists in upgrading of the quality and efficiency of the vacuum deaeration of water due to maintenance of an optimal mode of operation of the mechanical vacuum pump and due to exception of its operation at excessive power consumptions.

EFFECT: the invention ensures upgrading of the quality and efficiency of the vacuum deaeration of water.

1 dwg

FIELD: purification of liquids.

SUBSTANCE: tank has top section for water to be purified, bottom section for the purified water, the top section being mounted inside the bottom section, means for fastening sections, and lid made for permitting its securing to one of the sections of the tank. The top section is two-stage. The back wall of the first stage is provided with the top convex part and bottom concave part. The fastening means is made of a projection on the outer side of the section for the water to be purified and mating hollow in the inner side of the section and are arranged over the periphery of the sections. The device comprises filtering means, tank for purifying a liquid, and calendar composed of two members. One of the members is mounted on the filtering means, and the other one on the top section for the water to be purified.

EFFECT: improved performance and reduced cost.

3 cl, 5 dwg

FIELD: domestic appliances.

SUBSTANCE: filter comprises housing with inlet and outlet branch pipes, vertical baffles mounted inside the housing to define units for sorbents. The baffles are made of two cylinders axially aligned along the vertical axis of the housing to define single cylindrical unit and two ring units. The inner cylinder is mounted so that to provide a space between its bottom face and the bottom of the housing. The outer cylinder is mounted so that to provide a space between its top face and the lid of the housing.

EFFECT: enhanced reliability of the filter.

3 dwg

FIELD: purification of industrial sewage containing finely dispersed colloid organic and mineral impurities.

SUBSTANCE: the invention is dealt with the field of decomposition of the spent emulsive lubricating-cooling liquids (LCL) and may be used for purification of the spent industrial sewage containing the finely dispersive colloid organic and mineral impurities. The mode of decomposition of the LCL provides for introduction of the phosphoric acid into the LSS at stirring of the mix up to pH 2-3. Then the solution is heated up to the temperature of 65-80°C and after settling and removal of a lubricated phase, urotropine is added in the purified water phase at stirring and they exercise electrocoagulation of the partially purified water phase before production of a purified water phase. Then the product of treatment with the LSS is neutralized to meet parameters of maximum permissible concentration (MPC) for the sewage. The method ensures an increased level of purification the spent emulsive lubricating-cooling liquids from organic and mineral impurities at the expense of an increased duration of an effective functioning of the electrocoagulators.

EFFECT: the invention ensures an increased level of purification of the spent emulsive lubricating-cooling liquids from organic and mineral impurities due to an increased duration of an effective functioning of the electrocoagulators.

1 ex

FIELD: purification of natural waters.

SUBSTANCE: the invention is dealt with the methods of purification of natural waters intended for drinking with simultaneous production of carbon-to-mineral material, which may be used for soil development. the Method of purification of potable water from salts of hardness (Ca, Mg) with simultaneous production of carbon-to-mineral material of agroindustrial application provides for treatment of the water with a lime mortar [Ca(OH)2] and delivery of the produced reaction mixture in the form of a set jets all over the height and the circumference of the suspended layer of a ball-type granulated carbon - carbon material with specific surface of mesopores in terms of nitrogen of 0.5-100 m2 / g, bulk volume of pores 0.08-0.8 cm3 / g and value of pH - 9-11. The process is conducted up to 10-120 % saturation of sorbent by reaction particles and then sorbent is removed without regeneration. Extracted carbon-to-mineral material is treated with a solution of sulfuric either phosphoric acids or their mixture in an equivalent ratio. The method allows to reduce hardness of water and to attach useful properties to the spent sorbent.

EFFECT: the invention ensures reduction of hardness of water and attachment of useful properties to the spent sorbent.

4 cl, 1 dwg

FIELD: devices for purification of household and industrial sewage.

SUBSTANCE: the invention is dealt with devices for purification of household and industrial sewage and intended for electrical and cavitational treatment of sewage containing a large quantity of organic compounds. The device for purification of sewage consists of a body made out of a dielectric material partitioned by diaphragms for two electrode chambers and one working chamber, that contains a filtering material. The electrode chambers have cavitational field sources installed and the working chamber is supplied with a the bubbler installed in it. The technical result consists in an increase of recuperation of the filtering material at the expense of application of a cavitational field to it, decrease of the microbiological semination, and an increase of cavitational effect on particles.

EFFECT: the invention ensures an increase of the filtering material recuperation, decreased microbiological semination and increased the cavitational effect on particles.

1 dwg

Up!