Method of processing liquid low-activity level radioactive wastes
FIELD: radioactive waste treatment.
SUBSTANCE: suspension of magnetite obtained via electroerosion dispersing of iron-containing raw material in distilled water is added to solution to be processed. Adjusting pH of solution to 11-12 leads to precipitation. Decanted solution is subjected to magnetic separation followed by ion-exchange purification.
EFFECT: enhanced purification efficiency.
3 cl, 1 tbl
The invention relates to a method for processing liquid radioactive waste (LRW) low level of activity, containing suspended and colloidal impurities, and can be used mainly in nuclear power and reprocessing plants. The invention can be used for wastewater treatment from radionuclides.
Known methods of water purification, including coprecipitation with iron hydroxide with subsequent purification of decantate ion exchange [Assocition, WEA, Mijikai. Disposal of radioactive waste. M.: Energoatomizdat, 1985]. The disadvantages of this method are the formation of a large volume hydrate-sludge slurry that you want to localize, increasing the concentration of salts in decantate that reduces cycle ion exchange columns and water quality from radionuclides.
Closest to the present invention is a method of water purification magnetite obtained EDM dispersion of ferrous metals [RF Patent №2019521 C1, CL 02 F 1/58, 1/62]. The cleaning process consists of adding in weakly acidic or neutral solution suspensions of magnetite, stirring, adjusting the pH of the solution to 7.7-9.5 and the sludge separation.
The disadvantage of this method is its limited applicability. The method is applicable only for solutions in to the activities of the radionuclides are bound colloid-dispersed state. Also featured in the way that the pH range is not optimal for cleaning solutions from radionuclides. The resulting EDM method, particles of magnetite have micron and submicron size, which can lead to leakage of magnetite particles with sorbed on them radionuclides or in purified water during the decanting stage precipitate, or additional stages of treatment. The result is a reduction in the efficiency of the cleaning process waste.
An object of the invention is to provide a method of processing low-level LRW, allowing to increase the efficiency of cleaning solution from radionuclides at the stage of water treatment magnetite, to increase the efficiency of the separation of the precipitate of magnetite and purified solution to prevent precipitation of magnetite in the purified solution or additional treatment.
The problem is solved in a way that is that the treatment of LRW from radionuclides spend suspension of magnetite obtained EDM dispersion of iron-containing raw materials, at pH=11-12. As the iron-containing raw materials can be used scrap iron or iron ore pellets. To prevent leakage of magnetite particles in purified water or optional cleaning solution on the Le decanting undergoes magnetic separation.
The described method for processing liquid radioactive waste low level of activity is implemented as follows. In the processed solution is payable suspension of magnetite and alkali is added to adjust the pH of the solution to pH=11-12. Nuclides in the colloid-dispersed state, are sorbed on the particles of magnetite. After settling, the solution is decanted and sent for further purification from the soluble forms of radionuclides by known methods, such as adsorption or membrane, and the residue is directed to curing. To prevent leakage in the purified solution and a guaranteed allocation of particles of magnetite at the stage of additional purification using a magnetic separation.
The magnetite obtained by electroerosion, its sorption properties are not inferior to traditional collectors on the basis of hydroxides. For cleaning solutions from radionuclides optimal for use magnetite is the range of pH=11-12.
The results of purification of liquid radioactive solutions of low activity with magnetite at different values of pH are given in the table.
Results purification of liquid radioactive waste magnetite obtained EDM method
|pH plants the ora||The degree of sorption of radionuclides %|
|The proposed method is adsorption on magnetite at T:W=200 mg/l|
|Note: T:W is the ratio of solid phase to liquid, mg/l|
Example. The original solution volume of 20 l, volumetric α-activity 2,0*103Bq/l, volumetric β-activity of 5.1*104Bq/l after addition of 200 mg/l (dry matter) suspension of magnetite obtained electric is versionnum the dispersion of iron-containing materials, and adjusting the pH goes into the sump. As a result, after deposition for 1 hour and decanting the resulting solution with a density of αactivity 12 Bq/l, volumetric β-activity 2,5*103Bq/l, which served to further purification by ion exchange, and precipitated suspension (pulp) with a volume of 0.1 l, humidity is around 90% and a density of 1.1 g/cm3surround α-activity 4*105Bq/l, volumetric β-activity of 9.2*106Bq/l, which is supplied to the curing of known methods (cementing).
Thus, the proposed method allows to process LRW low level of activity, to increase the efficiency of cleaning solution from radionuclides to carry out the separation of the precipitate of magnetite from a purified solution and is guaranteed to prevent particles of magnetite in the purified solution or additional treatment.
1. Method for processing liquid radioactive waste low level of activity, including the introduction of feed solution suspensions of magnetite obtained EDM dispersion of iron-containing raw material in distilled water, adjusting the pH of the alkali solution, the release of sludge that is sent to the curing and cleaning of decantate, characterized in that the pH of the solution adjusted with alkali to 11-12, before additional clean is such decanted clear magnetic separation.
2. The method according to claim 1, characterized in that the raw material to obtain magnetite used iron ore pellets or scrap iron.
3. The method according to claim 1, characterized in that additional cleaning is performed by using ion-exchange.
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
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
FIELD: heat-power engineering; thermal power stations and boiler plants.
SUBSTANCE: proposed deaeration plant includes deaerator with starting water, heating agent and deaerated water pipe lines, as well as heating agent temperature regulator which is connected with dissolved oxygen sensor. Heating agent temperature regulator is additionally connected with deaerated water pH sensor. Proposed plant makes it possible to obtain required content of hard-to-evacuate gas (oxygen O2 or carbon dioxide CO2) due to change of heating agent temperature.
EFFECT: improved quality and enhanced economical efficiency.
FIELD: heat-power engineering; thermal power station and boiler plants.
SUBSTANCE: proposed deaeration plant includes deaerator with starting water, heating agent, deaerated water supply and discharge pipe lines, as well as flash steam flow regulator which is connected with dissolved oxygen content sensor. Flash steam flow regulator is additionally connected with deaerated water pH sensor. Proposed plant makes it possible to obtain required content of hard-to-evacuate gas (oxygen O2 or carbon dioxide CO2) due to change of flash steam flow rate.
EFFECT: enhanced economical efficiency and improved quality.
FIELD: heat-power engineering; thermal power stations and boiler plants.
SUBSTANCE: proposed deaeration plant includes deaerator with starting water, overheated and deaerated water pipe lines, as well as starting water temperature regulator which is connected with dissolved oxygen content sensor. Starting water temperature regulator is additionally connected with deaerated water pH sensor. Proposed plant makes it possible to enhance economical efficiency of plant due to obtaining required content of hard-to-evacuate gas (oxygen O2 or carbon dioxide CO2) through change of starting water temperature.
EFFECT: enhanced economical efficiency.
FIELD: heat-power engineering; thermal power stations and boiler plants.
SUBSTANCE: proposed deaeration plant includes de-aerator with starting water, heating agent and deaerated water pipe lines, as well as heating agent flow regulator which is connected with sensor showing content of dissolved oxygen. Heating agent flow regulator is additionally connected with deaerated water pH sensor. Proposed plant makes it possible to obtain required content of hard-to-evacuate gas (oxygen O2 or carbon dioxide CO2) due to change of flow rate of heating agent.
EFFECT: improved quality; enhanced economical efficiency.
FIELD: oxidation catalysts and waste water treatment.
SUBSTANCE: catalyst than may be used in hydrogen peroxide-mediated oxidation of phenol in waste waters at 50-70°C is based on montmorillonite clay and iron and aluminum ions intercalated in the form of polyoxometallate cation [Al12FeO4(OH)24(H2O)12]7+. Complete oxidation of phenol into CO2 and H2O with hydrogen peroxide is effected in presence of above-defined catalyst, which is characterized by low degree of washing-out of active component into solution, at 50-70°C, preferably in aqueous solutions with acidity close to neutral.
EFFECT: reduced expenses, simplified preparation procedure, and achieved environmental safety.
5 cl, 1 dwg, 3 tbl, 15 ex
FIELD: liquid purification.
SUBSTANCE: filtering material is made of piping knitted fabric produced by slicking . The priming fiber is made of synthetic threads , and slicking fiber is made of rubber threads which define fleecy surface on the face side. The length of the rubber thread in the loop is greater than that of the synthetic thread in the loop by a factor of 1.2-1.8. The piping knitted fabric receives cellulose fibrous cloth, rubber fibers or rubber crumb and polyurethane crumb whose volume ratio is 1:(2-4):(1.5-3), respectively.
EFFECT: enhanced quality of filtering.
2 dwg, 1 tbl
FIELD: agriculture and different industries; irrigation farming.
SUBSTANCE: the invention is pertaining to the field of agriculture, in particular, to an irrigation farming at construction of the irrigation and drainage systems with a closed cycle of a water rotation and also to the industrial and agricultural water supply facilities. The installation includes a water feeding duct with a sensor of mineralization of the water, a water separator and water outlets; an accumulator of the mineralized water with two sections, an accumulator of a desalinated water, an evaporator, pumping stations, feeding water pressure pipelines; an ice site with a counter-filtering screen, protective dikes, a cutoff drain and water outlets; apparatuses for a winter sprinkling to freeze on an ice block; a channel-collector of the saline solutions and the desalinated water; a gravity flow self-contained collector with water-intakes from the channel-collector;, a command and measuring complex (CMC) for control over the process of a water desalination in the collector; a power plant, a device for a heating of the air and a compressor to feed the heated air in the collector. Located sequentially around the ice-site accumulators of the mineralized and a desalinated water, an evaporator - are separated from the channel - collector by a ring-shaped dike and separated by bridges and their outer boundaries form a closed contour having a lineout of the territory within the limits of the landscape intended for creation of the installation. The depth of the evaporator is determined according to a mathematical dependence. The installation shall ensure desalination of the mineralized water by freezing with use of the natural climatic factors in conditions of a flat topography of the location at a high coefficient of land utilization within the limits of the area occupied by the installation.
EFFECT: the invention ensures desalination of the mineralized water by freezing with use of the natural climatic factors.
FIELD: waste water treatment.
SUBSTANCE: invention relates to treatment of waste waters originated from fluorine-containing polymer production. Fluorine-containing emulsifiers, in particular perfluorooctanoic acid, are bound by anion-exchange resins. Further, indicated emulsifiers are washed out from anionite with water-organic mixture containing some amount of ammonia and having boiling temperature below 150°C. Ammonia-containing solvent is preferably distilled away and emulsifier and ammonia-containing solvent are reused.
EFFECT: increased concentration of emulsifier in eluate.
5 cl, 4 tbl, 5 ex
FIELD: reactive sorbents.
SUBSTANCE: liquid is conditioned at pH 4-6 and then is brought into contact with chelating ion-exchange resin composed of grafted polyazocycloalkanes at temperature above or equal to 60°C.
EFFECT: enhanced metal removal efficiency.
35 ex, 9 dwg, 9 tbl, 5 ex
FIELD: water protection, particularly for prevention of water basin contamination with surface water received from agricultural lands.
SUBSTANCE: modular device comprises vertical partitions, which divide thereof into receiving, overflow and sediment chambers. Device includes several identical sections provided with partition chamber, clean water chamber, oil and floating rubbish gathering chamber and has filtering dam installed in intake channel bed.
EFFECT: simplified structure, increased cleaning efficiency.
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.