KR101819112B1 - A method for regenerating spent picking acid and filtering zirconium-containing precipitate - Google Patents

Abstract

According to the present invention, a device for reproducing waste pickling acid and separate a zirconium precipitate includes: a stirring tank storing and stirring a precipitator and waste pickling acid; a filter press part including a filter plate with a filter cloth placement part and an inlet and outlet; and a filtrate storage tank storing a filtered solution. The stirring tank is connected to the inlet of the filter press part by a pipe connecting a feed pump and an inlet valve in series. The pipe, connected to the outlet of the filter press part, penetrates an outlet valve and then branches so that a side is connected to the stirring tank through a first passage valve and the other side is connected to the filtrate storage tank through a second passage valve. According to the present invention, a method for reproducing waste pickling acid and separating a zirconium precipitate includes: a step of storing waste pickling acid of hydrofluoric-nitric acid containing zirconium in the stirring tank; and a step of generating a precipitate by mixing barium fluoride as a precipitator. The present invention is capable of making an advantageous effect for maintaining pickling acid performance with a low impurity concentration of waste hydrofluoric-nitric pickling acid containing zirconium, and enabling the separation of precipitates by applying a simple and reasonable filtering and separating method.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zirconium-containing precipitate,

The present invention relates to an apparatus and a method for recycling a zirconium-containing acid waste liquid and separating a zirconium deposit from a pickling waste liquid. More particularly, the present invention relates to an apparatus and a method for separating a zirconium deposit from a pickling waste liquid using barium fluoride (BaF ₂ ) (Zr), thereby regenerating the pickling waste liquid and separating the precipitate containing zirconium.

The bundle of nuclear fuel used in a nuclear power plant is manufactured by charging a uranium oxide sintered body into a zirconium alloy tube. In order to clean the contamination of the tube surface during the manufacturing process, pickle acid (HF) mixed with nitric acid (HNO ₃ ) ) Is widely used. When the cleaning efficiency is lowered below a certain level due to the increase of impurities such as zirconium (Zr) in the spent pickle acid used for washing the zirconium alloy tube, the pickling waste liquid is neutralized and discarded as industrial waste. Therefore, there is a need for improvement in terms of environmental problems and loss of zirconium resources related to this.

U.S. Pat. No. 4,105,469, which was patented in 1978, uses sodium fluoride (NaF) as a precipitating agent in a pickling solution to regenerate acidic waste liquid of hydrofluoric acid-nitric acid, thereby reducing the zirconium concentration in the solution through a precipitation reaction, Technology is disclosed.

However, analysis of residual sodium (Na) and zirconium (Zr) according to the addition amount of NaF showed that the amount of remaining Na increased sharply when a certain amount (4 wt%) or more of NaF was added, , The uniformity of the cleaned surface becomes worse, and it is difficult to apply the technique of regenerating the waste acid tax liquid by using NaF as a precipitant. In addition, when the amount of NaF added is insufficient, a gel-like precipitate is formed which is difficult to be filtered. As the amount of NaF added increases, the size of the precipitate tends to decrease, which makes it difficult to separate the precipitate.

United States Patent No. 4105469.

The present invention provides an apparatus for recovering a pickling waste liquid by mixing a precipitating agent with a pickling waste solution and separating the precipitate by a filter press method. In this apparatus, barium fluoride (BaF ₂ ) is used as a precipitant in pickling- To remove the zirconium to regenerate the pickling waste liquid and to separate the precipitate containing the zirconium.

The apparatus for separating and recovering a pickling waste solution and a zirconium precipitate according to the present invention comprises a filter plate having a stirring tank for receiving and stirring a precipitating agent and a pickling waste liquid and a filter sheet seating portion, the filter press portion having an inlet port and an outlet port, The filtration tank is connected to the inlet of the filter press by a pipe connecting the feed pump and the inlet valve in series and the pipe connected to the outlet of the filter press is branched after passing through the outlet valve One side is connected to the stirring tank through a first flow path valve and the other side is connected to the filtrate storage tank through a second flow path valve.

The apparatus for separating and recovering a pickling waste solution according to the present invention comprises a precipitant solution tank having a stirring rod and the precipitant solution tank is connected to an upper portion of the stirring tank by piping including a transfer pump have.

The filter for regenerating pickling waste liquid and separating zirconium precipitate according to the present invention includes a compressed air supply unit and the filter plate includes a compressed air port provided with a check valve so that the compressed air supplied from the compressed air supply unit is supplied to the filter cloth receiving unit of the filter plate. As shown in FIG.

The method for regeneration of pickling waste liquid and separation of zirconium precipitate according to the present invention is characterized in that a pickling waste solution of hydrofluoric acid-nitric acid containing zirconium is contained in a stirring tank and barium fluoride is mixed with a precipitant to produce a precipitate.

In the method of regenerating pickling waste liquid and separation of zirconium precipitate according to the present invention, the second flow path valve is shut off, the inlet valve, the outlet valve and the first flow path valve are opened, the feed pump is operated and the precipitate mixed acid waste solution A recycling step in which the pickling waste liquid filtered through the filter press section is again introduced into the stirring tank, and the filtrate storing step in which the pickling waste liquid filtered by opening the second flow valve and blocking the first flow valve enters the filtrate storage tank .

In the method of regenerating pickling waste solution and zirconium precipitate according to the present invention, water is filled in a precipitant solution tank, barium fluoride is used as a precipitant to stir the precipitant to be dispersed in water, and a suspension in which the precipitant is dispersed is stirred in a stirring tank To the transporting unit.

INDUSTRIAL APPLICABILITY The apparatus and method for recovering a pickling waste solution and a zirconium precipitate according to the present invention are advantageous in that the residual impurity concentration of the zirconium-containing hydrofluoric acid-nitric acid pickling waste solution is low to maintain pickling performance of reproduction.

Further, the apparatus and method according to the present invention have the effect of separating sediment by applying an inexpensive and simple filtration separation method because the size of the sediment is large.

The present invention has the effect of improving the separation performance and separation efficiency by separating the precipitate by using the filter cloth by allowing the filtration process of the precipitate slurry to be divided into two steps and changing the flow path.

INDUSTRIAL APPLICABILITY The present invention has the effect of reducing the amount of unreacted precipitant remaining and the concentration of residual metal impurities by using a suspension in which a precipitant is dispersed in distilled water and increasing the recovery rate of the precipitate.

The present invention has a beneficial effect in manufacturing a zirconium ingot by processing a precipitate or electrolytic smelting by lowering the water content of the precipitate by subjecting the precipitate to filtration after filtration.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of an apparatus for separating a pickling waste solution and a zirconium precipitate according to the present invention. FIG.
2 is a conceptual diagram of a filter press part used in the apparatus of the present invention.

Hereinafter, specific embodiments according to the present invention will be described. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

In the present invention, barium fluoride (BaF ₂ ) is introduced into a pickling solution of hydrofluoric acid-nitric acid containing zirconium in the cleaning process of a zirconium alloy tube by a precipitant to form and separate a precipitate, thereby reducing the metal impurity concentration, A method for regenerating pickling waste liquid to be regenerated and a method for separating precipitates and apparatus therefor.

The reaction formula in which zirconium is precipitated using a BaF ₂ precipitant in a hydrofluoric acid-nitric acid pickling solution containing zirconium is as follows.

ZrF ₄ + 2BaF ₂ = Ba ₂ ZrF ₈

The solubility (0.16 g / 100 g H ₂ O) of the BaF ₂ precipitant is much lower than that of the conventional NaF precipitant (4 g / 100 g H ₂ O), so that the concentration of residual impurities (Ba, Zr) is also low. In the case of Zr content of 1.3 wt% in the waste acid, BaF ₂ was added at a ratio of the above reaction equation, and the Ba concentration and remaining Zr concentration after 120 minutes were 169 ppm and 11 ppm, respectively. This is only 8% and 28% of the remaining Na and Zr concentrations when using NaF precipitants under similar conditions. Since the residual impurity concentration is low, it is more advantageous to maintain the pickling performance of regenerated spent pickle acid.

In addition, one must rely on more sophisticated means such as sediment (Na ₂ ZrF ₆₎ by conventional NaF precipitant has a particle size of 1 ㎛ reduced to less than a conventional filtration method or the like precipitate separation is not easy centrifugation by, BaF ₂ precipitant (Ba ₂ ZrF ₈ ) has a particle size distribution of 1 탆 or more and has an average size of 10 탆. Therefore, it is possible to separate sediments by applying a relatively inexpensive and simple filtration separation method.

On the other hand, when the powdery BaF ₂ precipitant is introduced into the hydrofluoric acid-nitric acid pickling waste solution, the reaction proceeds rapidly on the surface of the powder, and the reactant functions to prevent the progress of the reaction, and unreacted BaF ₂ may remain in the powder have. In the case where unreacted BaF ₂ remains, analysis by evaporation of the filtrate after separating the precipitate can confirm that the precipitant reacts with nitric acid to produce Ba (NO ₃ ) ₂ . In this case, the residual Zr increases in the pickling waste solution, and the recovery rate of the precipitate also decreases. Such a problem can be significantly improved by using a suspension in which BaF ₂ precipitant is dispersed in distilled water instead of directly using the precipitant in powder form.

The pickling waste solution regeneration and zirconium precipitate separation apparatus proposed in the embodiment of the present invention based on the technical contents described above is conceptually shown in Fig. Technical effects of the device according to the present invention will be described more clearly by the description of how to use the device described later.

The pickling waste liquid regeneration and zirconium sediment separation apparatus includes a filtration plate 210 having a stirring tank (Agitation Tank) 100 which receives and agitates a precipitating agent and a pickling waste liquid, and has an inlet port 230 and an outlet port 240. A filter press part 200 having an outlet and a filtrate storage tank 300 for receiving the filtered solution. The stirring tank 100 is connected to the inlet 230 of the filter press unit 200 by piping connecting the feed pump 110 and the inlet valve 120 in series. The pipe connected to the outlet 240 of the filter press unit 200 is branched after passing through an outlet valve 250 so that one side is connected to the stirring tank through the first flow valve 310, And is connected to the filtrate storage tank through a two-way valve (320).

The filter press unit 200 conceptually shown in FIG. 2 includes a filter plate 210 having a seating surface having fine protrusions 211 formed on its surface, and a filter cloth 270 is installed on the seating surface . When the filter plate 210 is pushed in the direction of the arrow by the pressure plate 220, a space sealed by the rubber O-ring 280 or the like is formed at the outer portion of the filter plate 220. The precipitate slurry flows into the space through the inlet 230, 271 can be filtered on the filter cloth 270. The operation of pressing the pressure plate 220 to form the sealing space is performed before operating the feed pump 110. [ The filtrate having passed through the filter cloth 270 has a structure capable of flowing through the valley between the fine protrusions and flowing out to the outlet 240. When a high pressure compressed air is supplied through the compression air hole 212 to the filter sheet 210 to be compressed air to be described later, a high pressure can be transmitted to the filter sheet seat portion of the filter sheet 210 . A check valve 213 is provided in the compression air hole 212 to prevent the filtrate from flowing backward during the filtration operation. The filter plate can be deformed so that a plurality of filters can be used in a stacked manner.

The filter cloth to be used shall not be so long as particularly limited with and can withstand the discharge pressure, the number of the distance and the precipitate (Ba ₂ ZrF ₈₎ effective mesh size (mesh size) with a feed pump 110, typically a polypropylene (polypropylene) Fabrics made of double-woven fabrics of appropriate size and shape are used.

A transparent window 260 is provided between the outlet 240 and the pipe branching part 261 in a pipe connected to the outlet 240 of the filter press part 200 so as to be able to check the state of the solution flowing out . The state in which the precipitate is mixed and the state in which the precipitate is sufficiently filtered and the clear filtrate is discharged can be easily distinguished through the transparent window 260. When the filtrate is in a clear filtrate state, the filtrate is changed from the recycling step to the filtrate storage step.

The pickling waste liquid regeneration and zirconium deposit separation apparatus preferably includes a precipitator solution tank 400 having a stirring rod 410. The precipitant solution tank 400 is connected to the upper portion of the stirring tank by piping including the transfer pump 420.

It is preferable to form a spray nozzle (Spray Nozzle) 430 at the end of the pipe to disperse the precipitant solution in the pickling solution of hydrofluoric acid-nitric acid.

The apparatus for recovering acid waste liquid and separating zirconium precipitate according to the present invention preferably includes an air compressor part (500), and supplies compressed air along an air line indicated by a dashed line in FIG.

The pressure plate 220 of the filter press unit 200 described above can open the pressure valve 510 provided in the air pipe to supply compressed air to the hydraulic cylinder to perform the pressurizing operation.

The feed pump 110 may be operated by using the compressed air supplied from the compressed air supply unit 500 and by opening the operation valve 520 and may be operated using an air operated double diaphragm pump . This pump has the advantages of high instantaneous discharge pressure and low possibility of failure due to corrosion.

Hereinafter, a method of using the apparatus described above will be described in more detail. The technical effect of the device according to the invention is further clarified by the method of use of the device described below.

In the stirring tank 100 of the pickling waste liquid regeneration and zirconium precipitate separating apparatus according to the present invention, an acid pickling waste liquid of hydrofluoric acid-nitric acid containing zirconium is received from the pickling process of the zircaloy tube, and barium fluoride (BaF ₂ ) Mix and stir to form a precipitate (Ba ₂ ZrF ₈ ).

The filtration process of the slurry produced in the stirring tank 100 is performed in two steps including a recycling step and a filtrate storing step. The recycling step is performed by shutting off the second flow path valve 320 and opening the inlet valve 120 and the outlet valve 250 and the first flow path valve 310 to operate the feed pump 110, Is filtered by the filter press section 200, and then the filtered waste acid liquid is again introduced into the stirring tank. After the recycling step, the second flow path valve 320 is opened, the first flow path valve 310 is closed, and the filtered pickling waste liquid enters the filtrate storage tank.

The reason for going through the recycling step is that the pore of the filter cloth is opened at the beginning of the filtration of the slurry slurry, so that some precipitate may pass through the filter cloth, so that the primary filtered solution is filtered into the stirring tank 100 Recycle. When the sediment is accumulated in the filtration pore cavity through recycling, the filtration efficiency is increased and the sediment having a small particle size is sufficiently filtered by the filter cloth. Therefore, the filtrate is stored by forming a flow path so that the waste acid tax solution enters the filtrate storage tank 300 It is used as regenerated pickle acid. Therefore, in the apparatus according to the present invention, the first flow path valve 310 and the second flow path valve 320 can be provided to change the flow path, thereby separating the precipitate (Ba ₂ ZrF ₈ ) by filtration using the industrial filter cloth, It is possible to improve performance and separation efficiency.

When the precipitant solution tank 400 is used, the tank is filled with water, barium fluoride (BaF ₂ ) is added as a precipitant, and the precipitant is stirred so as to be dispersed in water to prepare a suspension in which the precipitant is dispersed. And transferred to a stirring tank to be mixed with a pickling solution of hydrofluoric acid and nitric acid in a stirring tank.

As described above, the barium fluoride (BaF ₂ ) suspension is prepared using the precipitant solution tank 400 and mixed with the acidic waste solution of hydrofluoric acid-nitric acid to reduce the unreacted BaF ₂ remaining amount and the residual Zr concentration, It has an effect of increasing the recovery rate of the precipitate.

The operation valve 520 is closed to stop the operation of the feed pump 110 and the inlet valve 120 is closed and the compression valve 530 is opened So that the compressed air is blown into the compressed air holes 212 of the filter plate 210 to squeeze the precipitated solids 271 filtered by the filter cloth 270 into a dehydrated cake state. Thereafter, the pressure applied to the pressure plate 220 is released to desorb the precipitate cake.

The squeezing process may further reduce the water content of the precipitate, so that it is not necessary to carry out a separate drying process. Therefore, the sintering process is advantageous in manufacturing a zirconium ingot through processing of a precipitate cake or electrolytic smelting.

The invention described above is susceptible to various modifications within the scope not impairing the basic idea. Therefore, all of the above embodiments are to be construed as illustrative and not restrictive.

100: Agitation tank
110: Feed Pump
120: Inlet Valve
200: Filter Press Part
210:
211: fine protrusion
212:
213: Check Valve
220: Platen
230: Inlet
240: Outlet
250: Outlet Valve
260: Transparent window
261:
270: Filter cloth
271: Precipitated solids
280: Rubber O-ring
300: Filtrate Storage Tank
310: first flow valve
320: second flow valve
400: Precipitator solution tank
410: stir bar
420: Feed pump
430: Spray nozzle
500: Compressed Air Supply (Air Compressor Part)
510: Pressure Valve
520: Operation valve
530: Crimping valve

Claims (8)

delete delete delete delete delete A stirring tank for containing and stirring the precipitant and the pickling waste liquid,
A filter press section including an inlet port and an outlet port, the filter press section including a filtration plate seating section,
And a filtrate storage tank for containing the filtered solution,
The stirring tank is connected to an inlet of the filter press part by a pipe connecting the feed pump and the inlet valve in series,
The pipe connected to the outlet of the filter press part is branched after passing through the outlet valve and one side is connected to the stirring tank through the first flow path valve and the other side is connected to the filtrate storage tank through the second flow valve, And a zirconium precipitate separation apparatus,
A method for regenerating pickling waste liquid and separating zirconium precipitate, which contains an acidic waste liquid of hydrofluoric acid-nitric acid containing zirconium in a stirring tank and mixes barium fluoride with a precipitant to produce a precipitate. The method according to claim 6,
The second flow path valve is shut off and the inlet valve and the outlet valve and the first flow path valve are opened to operate the feed pump so that the precipitate mixed acid waste fluid generated in the stirring tank is filtered through the filter press section, A recycling step into the tank,
Wherein the second flow path valve is opened and the first flow path valve is shut off to perform the filtrate storing step in which the filtered spent acid washing liquid enters the filtrate storage tank. A stirring tank for containing and stirring the precipitant and the pickling waste liquid,
A filter press section including an inlet port and an outlet port,
A filtrate storage tank for containing the filtered solution, and
And a precipitant solution tank having a stirring rod,
The stirring tank is connected to an inlet of the filter press part by a pipe connecting the feed pump and the inlet valve in series,
A pipe connected to an outlet of the filter press part is branched after passing through an outlet valve and one side is connected to the stirring tank through a first flow path valve and the other side is connected to the filtrate storage tank through a second flow path valve,
Wherein the precipitant solution tank is a pickling waste solution regeneration apparatus connected to the upper portion of the agitation tank by piping including a transfer pump, and a method for regenerating pickling waste solution and separating zirconium precipitate using a zirconium precipitate separation apparatus,
The acidic tank waste liquid of hydrofluoric acid-nitric acid containing zirconium is contained in the stirring tank,
The precipitant solution tank is filled with water, and the precipitant is dispersed in water using barium fluoride as a precipitant,
A method for regeneration of pickling waste liquid and separation of zirconium precipitate by transferring a suspension in which a precipitant is dispersed to a stirring tank using a transfer pump.

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