RU47362U1 - DEPARTMENT FOR THE DEACTIVATION OF RADIOACTIVE WASTE OF RARE METALLIC PRODUCTION - Google Patents

Abstract

The proposed utility model relates to the field of metallurgy of non-ferrous, dispersed and radioactive metals and can be used, in particular, for the integrated processing and decontamination of radioactive multicomponent polymetallic production wastes, for example, salt wastes of rare-metal production - wastes from the chlorination process of loparite concentrates, in particular, spent salt-irrigation melts filter (SOF) of the chlorination of loparite concentrates in salt chlorinators. The objective of the proposed technical solution is to increase the complexity of the processing of production waste as man-made materials and increase the productivity of the process of decontamination of salt waste. The technical result that can be obtained by implementing the proposed technical solution is to ensure the extraction of valuable components from production waste and to reduce the number of operations and the duration of the process of decontamination of salt waste. Department for the decontamination of radioactive wastes of rare metal production, including a reactor for neutralizing and deactivating salt chloride solutions, connected to tanks-deactivators of barium chloride solutions of sulfate-containing inorganic compounds, a filter press for separating hydrated sulfate precipitate from deactivated chloride solutions, a reactor for preparing sodium hydroxide solution connected to reactors for neutralizing and deactivating saline chloride solutions and workshop wash water, in the course of which is directed to a filter press to separate the pulp from the hydroxide precipitate. New is that the department additionally contains containers-collectors of the initial liquid radioactive waste - salt chloride solutions / pulps and workshop wash water, the outlet of which is directed to additionally installed heated reactors with a stirrer for

pre-treatment of saline chloride solutions, the upper nozzles of the reactor are connected to dispensers of solutions of sodium hydroxide and high molecular weight flocculants, and the discharge pipe of the pulp is connected to an additional filter, equipped with a hopper-collector of sediment, draining the filtered solution has a connection to the reactor to neutralize and deactivate salt chloride solutions prefabricated hoppers for filter cake sediments from pretreatment of saline chloride solutions and pulps and oxyhydrate sediment after neutralization and deactivation of the workshop wash water, they have unloading devices, the outlet of which is directed to a sealed vehicle for transporting wet sediments to a mixer connected to a drying chamber and a calcining furnace equipped with an unloading device for calcined sludge, over which an exhaust probe connected to a water-irrigated a scrubber filled with a ball movable fluidized nozzle, the discharge from the scrubber is directed to the circulation tank, the outlet pipe of the suspension from the cat It has a connection to a filter press to separate the precipitate from the pre-treated saline chloride solution / pulp).

Description

The proposed utility model relates to the field of metallurgy of non-ferrous, dispersed and radioactive metals and can be used, in particular, for the integrated processing and decontamination of radioactive multicomponent polymetallic production wastes, for example, salt wastes of rare-metal production, wastes from the chlorination process of loparite concentrates, in particular, spent salt-irrigation melts filter (SOF) of the chlorination of loparite concentrates in salt chlorinators.

This waste - spent SOF melts contain an increased amount (up to 2.0-2.2%) of Th-232 and other products of its decay, as well as chlorides and oxychlorides of Ta, Nb, Ti, REE, Fe, Al, NaCl, KCl, MgCl ₂ , CaCl ₂ and others

A technical solution is known - a utility model (Certificate for PM No. 23787 with prior, dated 08.10.2001. IPC ⁷ C 22 V 60/02) - “Installation for the disposal of radioactive waste”, which can be used to decontaminate solutions and pulp formed during discharge of spent SOF melts into water. A known installation includes a reactor-converter, a filter press connected to it; the outlet pipe of the filtrate of the filter press is connected to the inlet of the decontamination tank; a reagent tank is connected to the inlet of the decontamination tank, and a filter press is installed after the decontamination tank.

The implementation of this known technical solution is as follows. A solution of radioactive intermediate products and (or) production wastes is pumped into the reactor-neutralizer, lime milk and 0.2-0.8% polyacrylamide solution are fed into the reactor. The radioactive sediment is sent to a special waste storage facility (HCO), and the filtrate is pumped to a decontamination tank, where chloride solutions are supplied

2 barium and sulfuric acid. The solutions are mixed, milk of lime is added to a pH of 7-9. The pulp from the decontamination tank is filtered on a filter press. The resulting radioactive precipitate (cake) is sent for disposal in the KhSO, and deactivated wastewater is discharged into the sewer.

The disadvantage of this known installation is its complexity and two-stage decontamination technology, which is associated with the presence of two filtering operations of the pulp and the release of radioactive fallout from the solution. Another drawback is the fact that this facility does not provide for the extraction and disposal of valuable components from waste, in particular, compounds of tantalum, niobium and titanium, which are lost together with the radionuclides and oxyhydrates of Fe, Al, etc. irrevocably - in the KhSO (special waste storage).

Of the known analogues, the closest in technical essence - the totality of features, and the technical result achieved in this case - is known (Patent for Utility Model No. 35633 by Application No. 2003130198/20 with prior, dated October 14, 2003; Reg. And publ.: 27.01. 2003; Bull. No. 3, 2003. MKI ⁷ C 22 V 60/02; 34/22; 60/02; G 21 F 9/04) “Technological complex for liquid radioactive waste processing” - adopted as a prototype,

The complex known for the prototype includes: a reactor for neutralizing radioactive salt solutions, a deactivating tank connected to metering tanks of barium chloride solutions of sulfate-containing inorganic compounds, a filter press for separating hydrated sulfate precipitates from deactivated chloride solutions, a reactor for preparing a hydroxide solution sodium, connected to the tank-neutralizer of washing water, the output of which is directed to a filter press for separation from the pulp after neutralization of washing water oxygene idratic precipitate.

A well-known technical solution - the prototype provides decontamination and neutralization of two types of radioactive waste:

solutions resulting from the discharge of spent radioactive melt of SOF into water and workshop washing water generated during washing of equipment, industrial sites, etc. In this case, 2 (two) types of radioactive fallout are formed: hydrate-sulfate - from the decontamination of SOF solutions to be buried in the special waste storage (HCO) and oxyhydrate precipitate (without sulfates), which can be disposed of (to recover Ta, Nb, Ti, REE ), for example, after drying, calcination, at the stage of chlorination of loparite concentrates (see RF Patent for ПМ №41022 с prior, dated 03.06.2004; Reg. and publ.: 10.10.2004; IPC ⁷ С 22 В 60/02; G 21 F 9/04).

The disadvantages of the known technological solutions of the prototype are:

- irretrievable loss of valuable components in the SOF (Ta, Nb, Ti) - after deactivation and neutralization of the radioactive deposit - cake - is removed in the HCO;

- unsatisfactory performance of operations of two-stage processes of neutralization - filtering - decontamination - filtering.

The objective of the proposed technical solution is to increase the complexity of the processing of production waste as man-made materials and increase the productivity of the process of decontamination of salt waste.

The technical result that can be obtained by implementing the proposed technical solution is to ensure the extraction of valuable components from production waste and to reduce the number of operations and the duration of the process of decontamination of salt waste.

The problem is solved with the achievement of the above technical result by the proposed utility model - "Department for the decontamination of radioactive waste of rare-metal production", including a reactor for the neutralization and decontamination of radioactive

salt chloride solutions, connected to the metering tanks of solutions of barium chloride and sulfate-containing inorganic compounds, a filter press for separating hydrated sulfate precipitates from deactivated chloride solutions, a reactor for preparing a sodium hydroxide solution, connected to a reactor for neutralizing and deactivating salt solutions and reactors neutralizers of workshop washing water, the output of which is directed to a filter press for separation of hydrated radioactivity from the pulp after neutralization of washing water Foot sediment. New in the claimed technical solution is that the department for the decontamination of radioactive wastes of rare metal production additionally contains: containers-collectors of the original liquid radioactive waste - salt chloride solutions / pulps and workshop washing water, the outlet of which is directed to the reactor for neutralization and deactivation, in front of the reactors To neutralize and deactivate saline solutions, a heated reactor with an agitator is additionally installed for pretreatment of the initial chloride solutions / pool bn, the upper nozzles of which have connections with tanks for workshop washing water, tanks for preparing solutions of high molecular weight flocculants and a reactor for preparing a solution of sodium hydroxide, and the outlet from the pretreatment reactor of the initial chloride pulp has a connection with an additional filter to isolate a water-insoluble residue from the pulp, draining the filtered saline has a connection with the reactor for neutralization and decontamination, prefabricated silos filter sediments filter presses After the pretreatment of saline solutions, pulp and oxyhydrate sludge after neutralizing and deactivating the workshop wash water, they have unloading devices and hatches, the outlet of which is directed to a sealed vehicle for transporting and delivering wet sludge to a mixer connected to a drying chamber and a calcining furnace equipped with

a calcined sludge unloading device over which there is an exhaust hood connected to a water-irrigated scrubber filled with a ball fluidized movable nozzle, the drain of which is directed to a circulation tank, the suspension pipe from which has a connection to a filter to separate the sludge from pre-treated saline chloride solution or pulp.

The above distinguishing features of the claimed technical solution (additional inclusion in the composition of the department for the decontamination of radioactive waste of rare-metal production of the reactor for pre-treatment of the initial chloride salt pulp, mixer, etc.), together with the known features, provides a solution to the problem with the achievement of the technical result, which consists in providing extraction from wastes from the production of valuable components (compounds of Ta, Nb, Ti, REE) and reducing the number of operations and the duration of the process of decontamination of saline precipitates of solutions, in particular from the hydraulic erosion of the spent melt of a rare-metal salt irrigation filter formed during the chlorination of loparite concentrates (REE titanium niobates).

At the same time, like the well-known technical solution — a set of structural elements, a certain arrangement of tank and filter equipment — the proposed technical solution, ensures the decontamination of almost all the main radioactive waste of rare-metal production (saline chloride solutions and workshop washing water) to the standards established for the workshop — residual activity of filtrates after neutralization and decontamination operations carried out in the proposed technical solution "Department for deactivation of rare metal production radioactive waste ”does not exceed 6 Bq / kg.

An analysis of the book, magazine and patent literature indicates that the proposed department for the decontamination of radioactive waste of rare-metal production has not been previously described and does not explicitly follow and should not follow from known sources of information.

Figure 1 shows the claimed utility model "Department for the decontamination of radioactive waste of rare metal production", which includes:

1 - capacity collection of the original radioactive salt chloride solutions / pulp;

2 - tank-collection shop washing water;

3, 4, 5 — heated reactors with stirrers equipped with upper nozzles for supplying initial solutions, waste water, reagents, and lower discharge nozzles;

3 - reactor for pre-treatment of the initial chloride pulp - saline;

4 - reactor for the neutralization and deactivation of chloride salt solutions;

5 - reactor for neutralization-deactivation of workshop washing water;

6 - a reactor for the preparation of a sodium hydroxide solution connected to a metering tank (7) of a sodium hydroxide solution;

8 - reactor for the preparation of sodium sulfate solution, connected to a metering tank (9) of sodium sulfate solution;

10 - a reactor for preparing a solution of barium chloride, connected to a metering tank (11) of a solution of barium chloride;

12 - a reactor for preparing a high molecular weight flocculant (Navy) solution, for example, polyacrylamide and / or throne or another flocculant, connected to a dosing tank (13) of the Navy solution;

14 - reactor for the preparation of a solution of FeCl ₃ and / or AlCl ₃ connected to a metering tank (15);

16 is a filter for separating from the initial chloride pulp after its preliminary processing, i.e. heat treatment, partial neutralization of NaOH and flocculation with a solution of high molecular weight flocculant (Navy);

17 - collection hopper of an insoluble precipitate filtered from pulp containing Nb, Ta, Ti, etc .;

18 - filter press for separation from chloride salt pulp after neutralization and deactivation of hydrated sulfate sludge;

19 - collection hopper of radioactive hydrate-sulfate sediment;

20 - filter press for separation from the pulp after neutralization-deactivation of workshop washing water of hydrated sludge;

21 - hopper collection hydrated sludge;

22 - precipitation mixer;

23 - a drying chamber;

24 - calcining furnace;

25 - discharge device calcined (and prepared for the preparation of a mixture for chlorination together with loparite) precipitation;

26 - exhaust hood;

27 - a water-irrigated cyclone filled with a spherical movable fluidized nozzle;

28 - a circulation tank connected to a filter to isolate insoluble precipitates from chloride pulp;

29, 30 - collections of purified, decontaminated, deactivated chloride solutions and workshop washing water.

Utility Model Implementation

Department for the decontamination of radioactive wastes of rare metal production in accordance with the claimed technical solution works as follows.

Rare metal radioactive waste to be decontaminated, in particular saline chloride solutions / pulps containing Na, K, Mg, Ca, REE, Fe, Al, Th chlorides and its daughter products

decomposition, chlorides and oxyhydrates of Ta, Nb and Ti and the dust fraction of non-chlorinated lopartite rare-metal concentrate formed during the hydraulic washing of the spent melt of the salt irrigation filter of the chlorination process of loparite rare-metal concentrates enter the collection tank (1), shop washing water - the effluent produced in the red when flushing equipment, industrial sites, when eliminating spills, etc., they come from all departments of the workshop to the neutralization and decontamination department in the failure tank nicks (2). From the collection tank (1), the initial salt chloride solutions / pulps are sent to the reactor (3) for pre-treatment: dilution, heat treatment and partial neutralization and flocculation. For this, workshop washing water is poured into the reactor (3) from the collection tank (2) —to dilute (1.5-3 times) the initial chloride salt solution / pulp. Dilution is carried out to reduce the salt content, change the density and improve the conditions of the subsequent pulp processing. The diluted pulp is heated with stirring, for example, by supplying sharp steam to the reactor, to 80-90 ° C and maintained at this temperature for 0.5-2.0 hours. In this case, a dilute sodium hydroxide solution (20-100 g / dm ³ ) is introduced into the pulp from the metering tank (7) to partially neutralize the pulp, provide deeper hydrolysis of the oxychlorides of Ta, Nb, and Ti and precipitate the oxyhydrates of Ta, Nb, and Ti . Neutralization is carried out under conditions that exclude precipitation of iron (III) oxyhydrate from the solution into the precipitate, for which a dilute sodium hydroxide solution is fed to the reactor slowly, with continuous stirring, until the formation of iron (III) hydroxide begins, then to the pulp from the metering tank ( 13) inject a solution of high molecular weight flocculant, for example a 0.1-0.2% solution of hydrolyzed polyacrylamide. The pulp is then kept without stirring for 0.5-2.0 hours and fed to a filter, for example, a suction filter or a filter press (16) equipped with a collection hopper (17), and

an insoluble precipitate is isolated from the pulp (Ta, Nb, and Ti oxyhydrates, the dust fraction of the non-chlorinated rare-metal — laparite concentrate, “removed” from the chlorinator with the steam mixture and trapped in the saline irrigation filter).

When the filter is filled with sediment, water is supplied to the filter - to displace the mother liquor from the sediment phase, the promoters are sent to collection tanks (1) and (2).

The chloride salt solution filtered on a filter press (16) is pumped (or fed by gravity) into a heated reactor (4) with a stirrer to neutralize and deactivate the solutions. For this, sodium hydroxide solution (80-120 g / dm ³ ) is successively fed to the reactor (4) to a pH of 10-12. The solution in the reactor (4) is heated to 80-90 ° C. The NaOH solution is supplied with the stirrer switched on, then the sodium sulfate solution is sequentially poured into the reactor from the metering tank (9) and then the barium chloride solution from the metering tank (11). The pulp is mixed, if necessary, adjusting the pH of the pulp (within 11-12) by feeding NaOH from the metering tank (7). Then, a solution of iron (III) and / or aluminum chlorides is fed into the pulp - into the reactor (4) from the batcher (15). The FeCl ₃ and / or AlCl ₃ solution is supplied with continuous stirring of the pulp at a temperature in the reactor of 80-90 ° C. Stirring is carried out for 0.5-1.0 hours, after which the pulp in the reactor is held without stirring for 1-2 hours.

Note. Studies and tests showed that sequential treatment of chloride (pre-diluted) solutions of Na ₂ SO ₄ , BaCl ₂ , FeCl ₃ , AlCl ₃ , a certain temperature, pulp holding time, i.e. the time of precipitation formation ensures the decontamination of multicomponent saline chloride solutions to the requirements established in accordance with applicable regulatory documents (NRB, OSPORB). It should be noted that the decontamination process in the proposed technical solution proceeds in one

reactor, without an intermediate operation of filtering the pulp, which greatly simplifies the process and increases its productivity.

After neutralization and deactivation, the pulp from the reactor (3) is fed (pumped) to a filter press (18) equipped with a collection hopper (19) of a hydrated sulfate precipitate. After the filter press, the chloride solution is collected in the collection tank (29) and, after a control measurement of activity, is discharged into the sewer. After filling the filter with radioactive fallout, the filter is unloaded, the precipitate is collected in a collection hopper, wherefrom, through a unloading device and an unloading hatch, special machines are unloaded into a sealed body and sent either to the special waste storage facility (CSW) - radioactive waste landfills, or sent to the waste solidification operation by means of them mixing with cementitious materials and converting the wet radioactive precipitate - cake - into a cured state, i.e. environmentally friendly form - not a dusty and water-insoluble state, resistant to atmospheric influences and not harming the environment, public health and staff.

To neutralize, neutralize and deactivate the workshop wash water, they are pumped (or fed by gravity) from the collection tank (2) into a heated reactor with a stirrer (5). Wastewater in the reactor is heated to 80-90 ° C, for example by supplying sharp steam to the reactor; when the stirrer is switched on, a solution of sodium hydroxide is fed from the metering tank (7) until the pH in the pulp is 10-12, the pulp is stirred 0.25-0.5 hours and then kept without stirring for 0.5-2 hours, then pulp from the reactor (5) is fed (pumped) to the filter press (20). Neutralized and deactivated wastewater is collected in a collection tank (30) and, after a control measurement of activity, wastewater is either discharged into the workshop (factory) sewer or reused directly in the rare-metal production workshop for washing equipment, industrial sites, and preparing various

solutions (NaOH, Na ₂ SO ₄ , Navy, etc.). After filling the filter press (20) with sediment (Fe, Nb, Ta, Ti, REE and other oxyhydrates), the sediment is discharged into the collection hopper (21), from where the sediment is discharged through the discharge hatch into a sealed vehicle body - “special vehicles” and sent to the mixer (22), where this precipitate is mixed with another precipitate from the collection hopper (17), which also contains rare, scattered metals and REEs isolated from the initial chloride salt solution / pulp on the filter (16). After mixing, the precipitates are sent for dehydration to a special chamber (23) to extract moisture from the precipitation - water from the precipitation phase, and then the dried precipitate is loaded into a calcination furnace (24) to convert Ta, Nb, Ti, and REE oxyhydrates to oxides and thereby provide the possibility their subsequent use together with loparite concentrate. The calcined precipitate is discharged from the furnace (24) and sent to the stage (operation) of preparing the initial mixture for chlorination. To prevent dust generation at the workplace during unloading and to prevent harmful effects on the health of staff, using an exhaust hood (26), the dust-gas mixture is sucked out and fed for cleaning to a water-irrigated cyclone (27) filled with a fluidized ball movable nozzle connected to a circulation tank ( 28), the output of which is directed to a filter to isolate an insoluble precipitate from the initial chloride solution / pulp.

Calculations, studies and tests have shown that the implementation of the proposed utility model - “Department for the decontamination of radioactive waste from rare-metal production” provides a solution to the problem - increasing the complexity of processing waste from rare-metal production, increasing the productivity of the process of decontamination of salt chloride solutions. At the same time, an increase in the degree of extraction of valuable components (Ta, Nb, Ti, REE) from production wastes is achieved and the number of decontamination operations is reduced

salt waste - by combining in one reactor the operations of neutralizing acid chloride radioactive solutions with sodium hydroxide and the decontamination operation by sequential treatment with Na ₂ SO ₄ and BaCl ₂ solutions, then (for purification from radium and other radionuclides) with FeCl ₃ and / or AlCl ₃ solutions .

Technical and economic calculations showed that the economic effect at only one enterprise, in one workshop is more than 20 million rubles per year.

Claims (1)

Department for the decontamination of radioactive wastes of rare metal production, including a reactor for neutralizing and deactivating salt chloride solutions, connected to tanks-deactivators of barium chloride solutions of sulfate-containing inorganic compounds, a filter press for separating hydrated sulfate precipitate from deactivated chloride solutions, a reactor for preparing sodium hydroxide solution connected to reactors for neutralizing and deactivating saline chloride solutions and workshop wash water, in the passage from which is directed to a filter press for the separation of hydroxide precipitate from the pulp, characterized in that the compartment additionally contains containers-collectors of the initial liquid radioactive waste - salt chloride solutions / pulps and workshop washing water, the outlet of which is directed to additionally installed heated reactors with a mixer for pre-treatment of salt chloride solutions, the upper nozzles of the reactor are connected to dispensers of solutions of sodium hydroxide and high molecular weight flocculants, and to the pulp discharge, it is connected to an additionally installed filter equipped with a sediment collection hopper, the drain of the filtered solution has a connection to a reactor for neutralizing and deactivating saline chloride solutions, prefabricated silos of filter presses from pre-treatment of saline chloride solutions and pulps and oxyhydrate sediment after neutralization and decontamination of workshop washing water has unloading devices, the outlet of which is directed to a sealed vehicle for transporting wet adkov to the mixer, having a connection with the drying chamber and the calcining furnace, equipped with a discharge device of calcined sludge, over which there is an exhaust hood connected to a water-irrigated scrubber filled with a ball movable fluidized nozzle, the discharge from the scrubber is directed to the circulation tank, the suspension outlet pipe from which has connection with a filter press to separate the precipitate from the pre-treated saline chloride solution / pulp.