阅读说明：本技术 海绵铁滤料活化复用方法 (Sponge iron filter material activation and reuse method ) 是由 牛洁 王扬 李存增 于 2020-12-25 设计创作，主要内容包括：本发明提供了一种海绵铁滤料活化复用方法,该方法将淋洗液通入海绵铁滤料所在的处理装置中,进行原位活化。该方法避免了频繁更换动态反应床中的反应料,延长反应料寿命,使海绵铁得到循环利用,活化后的海绵铁滤料活性高,稳定性好,实现高质量的处理含铀废水,满足铀矿等规模化生产的需要。(The invention provides an activation and reuse method of a sponge iron filter material. The method avoids frequent replacement of the reaction materials in the dynamic reaction bed, prolongs the service life of the reaction materials, recycles the sponge iron, has high activity and good stability of the activated sponge iron filter material, realizes high-quality treatment of uranium-containing wastewater, and meets the requirements of large-scale production of uranium ores and the like.)

1. The method for activating and reusing the sponge iron filter material is characterized in that leacheate is introduced into a treatment device where the sponge iron filter material is located to carry out in-situ activation.

2. The method according to claim 1, characterized in that it comprises in particular the steps of:

step 1, adding leacheate into a uranium-containing wastewater treatment device;

step 2, washing the sponge iron filter material by using leacheate, and discharging waste leacheate after the washing is finished;

preferably, the method further comprises the step 3: and circularly washing the sponge iron filter material again to obtain the activated sponge iron filter material.

3. The method according to claim 1 or 2, wherein in step 1, the leacheate is a neutral or acidic inorganic solution, and the pH value of the leacheate is 0.1-8.

4. The method as claimed in any one of claims 1 to 3, wherein in step 1, the treatment device is a dynamic reaction bed, the dynamic reaction bed comprises a plurality of sections of separation columns, the separation columns are provided with a wastewater inlet and a wastewater outlet and internally provided with blocky sponge iron filter materials, and the plurality of sections of separation columns are in sealed butt joint.

5. The method according to any one of claims 1 to 4, wherein the effective aspect ratio of the separation column is (3-140):1, and the height of the separation column is 10-140 cm.

6. The method as claimed in any one of claims 1 to 5, wherein the bulk sponge iron filter material has a bulk density of 0.4-3.0g/cm in the dynamic reaction bed³。

7. The method according to any one of claims 1 to 6, wherein the flow rate of the leacheate in the step 2 is 30-550 mL/min.

8. The method according to any one of claims 1 to 7, wherein in step 3, after step 2 is completed, the sponge iron is rinsed with a neutral leachant or pumped air.

9. A method for treating uranium-containing wastewater by using a dynamic reaction bed of sponge iron filter materials, which is characterized in that the method activates the sponge iron filter materials to circularly treat the uranium-containing wastewater by using the method of any one of claims 1 to 8.

10. The method according to claim 9, characterized in that it comprises in particular the steps of:

step a, filling a blocky sponge iron filter material to obtain a dynamic reaction bed;

b, adjusting the pH value of the uranium-containing wastewater to obtain wastewater to be treated;

c, treating the uranium-containing wastewater through a dynamic reaction bed to obtain treated wastewater;

d, after the sponge iron filter material is saturated, activating the reused sponge iron filter material to obtain an activated dynamic reaction bed;

and e, introducing the uranium-containing wastewater again for treatment.

Technical Field

The invention belongs to the technical field of radioactive wastewater treatment, and particularly relates to an activation and reuse method for a reaction material for treating uranium-containing wastewater.

Background

As a nuclear energy fuel which is widely used, along with the continuous development of the global atomic energy industry, uranium can generate a large amount of radioactive wastewater in the processes of uranium ore mining, smelting and the like, the potential threat to human health and the natural ecological environment is becoming serious day by day, and higher requirements are put forward on the treatment technology of the radioactive wastewater.

Uranium generally exists in the form of hexavalent uranyl ions in wastewater, and when hexavalent uranyl is reduced to tetravalent uranium, flocculent precipitates can be formed, so that the uranium can be separated from a water body. At present, the adsorption media used for reducing, adsorbing and separating uranium in uranium-containing wastewater mainly comprise zero-valent iron, hydroxyapatite and the like. On one hand, the stability and the persistence of the uranium removal medium and the reaction material which are used at present are poor, the activity is reduced quickly, and on the other hand, the uranium substances are difficult to be activated and reused after being deposited in zero-valent iron and hydroxyapatite. Therefore, after the uranium-bearing wastewater is treated, a certain amount of radioactive reaction materials are required to be treated. In addition, in the uranium mining process, contaminated groundwater needs to be treated, for example, in the process of treating radioactive groundwater by adopting a permeable reactive barrier (PRB wall), the PRB wall is buried underground, so that the problems of long treatment period, complex process flow, high cost of reaction materials, frequent replacement of the reaction materials, inconvenience in continuous operation, high maintenance cost and the like exist.

Therefore, there is an urgent need for a reactive material and an activation multiplexing method capable of activating and multiplexing, which can prolong the service life of the PRB wall, reduce the maintenance frequency, and meet the requirements of large-scale production process and subsequent treatment.

Disclosure of Invention

In order to solve the above problems, the present inventors have conducted intensive studies and have provided a method for activating and reusing a reactant. The invention provides a method for activating and reusing a sponge iron filter material by constructing a dynamic reaction bed with the sponge iron filter material to treat uranium-containing wastewater, and the method can circularly treat the uranium-containing wastewater by utilizing the dynamic reaction bed constructed with the sponge iron filter material capable of activating and reusing, prolong the service cycle of reaction materials, reduce the treatment capacity of waste reaction materials and has important significance for the treatment of radioactive wastewater, thereby completing the invention.

The first aspect of the invention aims to provide a sponge iron filter material activation and reuse method, wherein leacheate is introduced into a treatment device where a sponge iron filter material is located for in-situ activation, and the method specifically comprises the following steps:

step 1, adding leacheate into a uranium-containing wastewater treatment device;

step 2, washing the sponge iron filter material by using leacheate, and discharging waste leacheate after the washing is finished;

preferably, the method further comprises the step 3: and circularly washing the sponge iron filter material again to obtain the activated sponge iron filter material.

The second aspect of the invention aims to provide a method for treating uranium-containing wastewater by using a dynamic reaction bed of sponge iron filter materials, wherein the method activates the sponge iron filter materials to circularly treat the uranium-containing wastewater by using the method of the first aspect of the invention.

The method specifically comprises the following steps:

step a, filling a blocky sponge iron filter material to obtain a dynamic reaction bed;

b, adjusting the pH value of the uranium-containing wastewater to obtain wastewater to be treated;

c, treating the uranium-containing wastewater through a dynamic reaction bed to obtain treated wastewater;

d, after the sponge iron filter material is saturated, activating the reused sponge iron filter material to obtain an activated dynamic reaction bed;

and e, introducing the uranium-containing wastewater again for treatment.

The method for activating and reusing the sponge iron filter material and the method for treating the uranium-containing wastewater provided by the invention have the following beneficial effects:

(1) the sponge iron filter material activation and reuse method can activate the sponge iron filter material in situ, does not need to take the sponge iron filter material out of the treatment device, is convenient to treat, and is suitable for large-scale treatment of uranium-containing wastewater.

(2) The method for activating and reusing the sponge iron filter material has the advantages that the used leacheate is simple in component, is carried out by adopting a water system, is low in pollution and small in usage amount, and plays a role in uranium concentration.

(3) The activation multiplexing method of the sponge iron filter material has good activation effect, and the activated sponge iron filter material can be used for treating uranium-containing wastewater for multiple times after being regenerated, so that the sponge iron filter material can be ensured to stably treat uranium-containing wastewater for a long time.

(4) According to the invention, the uranium-bearing wastewater is treated by using the activated and reusable sponge iron filter material to construct the dynamic reaction bed, the treatment method is simple, the reaction material can keep stable and high activity for a long time, and the ensured facility can stably run, especially can be applied to a PRB wall, so that frequent maintenance of the PRB wall is avoided, and in-situ activation is realized.

Drawings

Fig. 1 shows a graph of the change of the uranium removal rate in wastewater after the uranium-containing wastewater is circularly treated by using a sponge iron filter material before activation, a water-activated sponge iron filter material and an acid-activated sponge iron filter material for 24 hours in the embodiment of the invention.

Detailed Description

The present invention will now be described in detail by way of specific embodiments, and features and advantages of the present invention will become more apparent and apparent from the following description.

The invention provides a method for treating uranium-containing wastewater by constructing a reaction bed with a sponge iron filter material, and provides a method for carrying out in-situ activation and reuse on the sponge iron filter material after absorbing uranium substances, so that a reaction material can be continuously used in the reaction bed, the problem that the reaction material needs to be frequently replaced in the existing underground water permeable reaction wall is solved, the service cycle of the reaction material is prolonged, and maintenance operation is reduced.

The invention aims to provide a method for activating and reusing a sponge iron filter material, which is used for activating leacheate by introducing the leacheate into a treatment device where the sponge iron filter material is located, and specifically comprises the following steps:

step 1, introducing leacheate into a uranium-containing wastewater treatment device.

The leacheate is a neutral or acidic inorganic solution, is preferably one, two or more of water, hydrochloric acid, nitric acid and sulfuric acid, and is more preferably water and/or hydrochloric acid.

The pH value of the leacheate is 0.1-8, preferably 0.2-6, and more preferably 0.3-4.

The weight of the leacheate used for treating the sponge iron filter material is not more than 120g per liter, preferably not more than 80g per liter, and more preferably not more than 50g per liter.

Before leaching liquid is introduced into the uranium-containing wastewater treatment device, the wastewater in the treatment device needs to be emptied. The leacheate is connected to a water inlet or a water outlet of a uranium-containing wastewater treatment device, and is preferably connected to the water inlet.

The invention does not specifically limit the wastewater treatment device, and can be used for treating uranium-containing wastewater. The treatment device of the invention adopts a dynamic reaction bed.

The dynamic reaction bed comprises a plurality of sections of separation columns, the separation columns are provided with a wastewater inlet and a wastewater outlet, massive sponge iron filter materials are filled in the separation columns, and the plurality of sections of separation columns are in sealed butt joint. The dynamic reaction bed comprises 1-8 sections of separation columns, preferably 2-4 sections of separation columns.

The bulk density of the blocky sponge iron filter material in the dynamic reaction bed is 0.4-3.0g/cm³Preferably 0.8 to 2.5g/cm³More preferably 1.2 to 2.0g/cm³。

The effective height-diameter ratio of the separation column is (3-140):1, preferably (5-120):1, and more preferably (7-100): 1. The height of the separation column is 10-140cm, preferably 14-120cm, more preferably 18-100cm, wherein the effective height-diameter ratio is the ratio of the height of the blocky sponge iron filter material capable of being filled in the separation column to the inner diameter of the separation column.

The dynamic reaction bed is single-stage, two-stage or multi-stage treatment, wherein a certain stage of treatment comprises a plurality of sections of separation columns.

And 2, washing the sponge iron filter material by using the leacheate, and discharging the waste leacheate after the washing is finished.

The sponge iron filter material is washed in a mode that the leacheate is continuously or discontinuously introduced, preferably, the quantitative leacheate is used for circular washing, so that the leacheate can be used for circularly washing the sponge iron filter material to the maximum extent, and the use amount of the leacheate is reduced.

The flow rate of the leacheate is 30-550mL/min, preferably 40-500mL/min, and more preferably 50-450 mL/min. The washing time is 1-20min, preferably 2-15min, more preferably 3-10 min.

In a preferred embodiment of the invention, the flow rate is controlled in stages, preferably in a plurality of stages, the next stage being from 1.2 to 1.7 times the flow rate of the previous stage. For example, the control is carried out in four stages, during the first-stage flushing, the content of uranium in the sponge iron filter material is higher, the content of uranium in the leacheate is low, and at the moment, the leacheate with low flow rate is adopted for flushing; during the second stage of flushing, increasing the content of uranium in the leacheate along with the flushing, and flushing by adopting the leacheate with a medium flow rate I, wherein the medium flow rate I is 1.2-1.7 times of the low flow rate; in the third stage, the leacheate with the medium flow rate II is adopted for washing, wherein the medium flow rate II is 1.0-1.7 times of the medium flow rate I; and in the fourth stage of flushing, flushing by adopting the eluent with high flow rate, wherein the high flow rate is 1.2-1.7 times of the medium flow rate II.

In the present invention, when water is used as the eluent, the flow rate of the eluent is 350mL/min, preferably 400mL/min, and more preferably 450mL/min, which is 120-.

In the present invention, when an acidic solution is used as the eluent, the flow rate of the eluent is 30 to 90mL/min, preferably 40 to 80mL/min, and more preferably 50 to 70 mL/min.

And discharging the waste leacheate after the leacheate washes the sponge iron filter material, and emptying the wastewater treatment device.

Preferably, the method further comprises the step 3: and circularly washing the sponge iron filter material again to obtain the activated sponge iron filter material.

After step 2 is completed, the sponge iron is rinsed with neutral leacheate or pumped with air, preferably water. After the leacheate is washed, part of the leacheate remains in the dynamic reaction bed, neutral leacheate is used for washing or air is pumped in, the reduction of the residue of the leacheate is facilitated, and especially when acidic leacheate is used, the acidic leacheate is retained in the dynamic reaction bed for a long time, so that equipment is corroded, and the sponge iron filter material is consumed.

The flow rate of the neutral leacheate or the air is 50-70 mL/min. The washing time is 1-15 min.

When the sponge iron is immediately put into use after being activated and reused, the step 3 is optionally carried out.

The second aspect of the invention aims to provide a method for treating uranium-containing wastewater by using a sponge iron filter material dynamic reaction bed, which specifically comprises the following steps:

step a, filling a blocky sponge iron filter material to obtain the dynamic reaction bed.

Firstly, the sponge iron filter material is subjected to crushing pretreatment. After treatment, the average particle size of the blocky sponge iron filter material is 0.1-3cm, preferably 0.3-2cm, and more preferably 0.6-1 cm.

According to the invention, the activity of the sponge iron filter material for treating uranium-containing wastewater is high, sponge iron is kept in the particle size range of 0.1cm to 3cm in the wastewater treatment process of the dynamic adsorption column, the arrangement of the sponge iron filter material in the dynamic column can be well utilized, uranium substances in the wastewater can be kept in the sponge iron filter material after reaction, meanwhile, the wastewater treatment speed can be increased, the wastewater treatment capacity can be increased, the phenomena of blocking and channeling of common iron powder and other reaction materials are avoided, the requirement in the actual uranium mining process is met, and the PRB wall can stably run for a long time.

The dynamic reaction bed is according to the first aspect of the invention.

And b, adjusting the pH value of the uranium-containing wastewater to obtain wastewater to be treated.

The concentration of uranium in the uranium-containing wastewater is not more than 180mg/L, preferably not more than 20mg/L, and more preferably not more than 5 mg/L.

After the pH value is adjusted, the pH value of the uranium-containing wastewater is 4-10, preferably 4-8.5, and more preferably 7-7.5.

In the process of treating uranium-containing wastewater, the adsorption reaction treatment process is a comprehensive action process. In part of the reaction process, the sponge iron filter material is used as a primary battery, ferrous iron Fe (II) generated by the anode enters the solution and is used as a reducing agent to react with U (VI) in the solution, so that the U (VI) is reduced into U (IV) and deposited in the sponge iron filter material, and part of Fe (II) is oxidized into ferric iron Fe (III). As the reaction proceeds, the pH increases, and Fe (II) or Fe (III) oxides and hydroxides are formed, where Fe (OH)₃And Fe (OH)₂Has stronger adsorption-flocculation activity, can adsorb a large amount of micro particles, metal ions and organic macromolecules dispersed in the wastewater to flocculate and precipitate, and simultaneously, the oxides and hydroxides are adsorbed on the surface of the sponge iron.

A large number of experiments prove that the smaller the pH value is, the better the treatment effect of the sponge iron filter material is. However, in actual operation, the influence of the pH value on uranium removal is multifaceted, and when the pH value is less than 4, the acid consumption and the sponge iron consumption are increased, so that the treatment cost is increased, and the Fe in water is increased²⁺The content of (A) increases the color of effluent, needs subsequent treatment, and also has the corrosion problem of equipment and pipelines; when the pH value is more than 1At 0, the generation and sedimentation of hydroxide and oxide of the iron are accelerated due to the enhancement of the alkalinity of the environment, the reaction activity of the sponge iron is reduced, and the service life of the reaction material is shortened. And the pH value of the wastewater treated by the dynamic column in the invention is increased and the acidity is weakened.

And c, treating the uranium-containing wastewater through a dynamic reaction bed to obtain treated wastewater.

The flow rate of the uranium-bearing wastewater at the water inlet is not more than 120 mL/min. The uranium-bearing waste water provides pressure for uranium-bearing waste water in the dynamic column at the velocity of flow of water inlet, through the velocity of flow of adjustment waste water to control the dwell time and the uranium-bearing waste water treatment rate of uranium-bearing waste water in the dynamic column.

And d, after the sponge iron filter material is saturated, activating the reused sponge iron filter material to obtain the activated dynamic reaction bed.

And after the sponge iron filter material is saturated, closing the water inlet valve of the uranium-containing wastewater, opening the air inlet valve of air, and discharging the uranium-containing wastewater in the dynamic reaction bed. After the completion, the air inlet valve is closed, and the water inlet valve of the leacheate is opened to carry out activation and reuse.

The activation and reuse method of the sponge iron filter material is as described in the first aspect of the invention. Preferably, step 1 and step 2 of the method of the first aspect of the invention are carried out.

And e, introducing the uranium-containing wastewater again for treatment.

In a preferred embodiment of the invention, after the activation and reuse, before the uranium-containing wastewater is treated, the pH of the uranium-containing wastewater is adjusted to obtain the uranium-containing wastewater to be treated.

The pH value of the uranium-containing wastewater to be treated is 7-11, preferably 7.5-10, and more preferably 8-9.

By utilizing the activation multiplexing method of the sponge iron filter material, the sponge iron filter material can be activated in situ, the reaction materials in the dynamic reaction bed are prevented from being replaced, the service life of the reaction materials is prolonged, and the treatment of waste reaction materials is reduced. According to the invention, the activated and reusable sponge iron filter material is used for constructing the dynamic reaction bed for treating the uranium-containing wastewater, so that the treatment efficiency is high, the activity is high, the stability is good, the long-term stable operation can be realized, and the requirements of large-scale production of uranium ores and the like are met.

Examples

The performance indexes of the sponge iron filter material used in the invention are as follows:

iron element content%: 96-97 percent;

content of metallic iron: more than or equal to 90 percent;

carbon and impurities: 3-4%;

density: 2.3 to 2.7g/cm³；

Bulk density: 1.7 to 1.88g/cm³。

Example 1

And (4) treating the uranium-containing wastewater by using a separation column A. The separation column A is an organic glass column body, the inner diameter is 10mm, the height is 40cm, the diameters of the upper end liquid inlet and the lower end liquid outlet are 0.46cm, the water outlet is provided with filter cloth, the water inlet is communicated with the four-way joint, so that the water inlet is respectively connected with discharge ports of uranium-containing wastewater, air and leacheate, and the ball valve is used for controlling opening and closing. The water outlet is externally connected with a silicone tube. The opening and closing of the inlet and the outlet are controlled by ball valves.

37.5g of a blocky sponge iron filter material with the average particle size of about 1cm is filled into the separation column A, the filling height is 35cm, and the upper port is sealed to form the dynamic reaction bed. Controlling the flow rate of the uranium-bearing wastewater at a water outlet to be 101mL/min, wherein the water inlet is arranged at the bottom of the dynamic reaction bed, and the water outlet is arranged at the top of the dynamic reaction bed.

And (3) introducing 2400mL of uranium-containing wastewater for treatment for 24h in the 1 st circulation, wherein the concentration of the uranium-containing wastewater is 150 mg/L. The initial pH value of the uranium-containing waste water is 7.45. The concentration of the uranium-bearing wastewater after a certain time is sampled and measured, and ICP is adopted for testing, and the test results are shown in Table 1.

Table 1:

serial number	Reaction time (h)	Uranium concentration (mg/L)	Uranium removal rate
				1	2	62.4	58％
2	5	24.4	83.7％
				3	24	0.06	99.9％

And 2 nd circulation, introducing 2300mL of uranium-containing wastewater for treatment for 24h, wherein the concentration of the uranium-containing wastewater is 150 mg/L. The initial pH value of the uranium-containing waste water is 7.45. The concentration of the uranium-bearing wastewater after a certain time is sampled and measured, and ICP is adopted for testing, and the test results are shown in Table 2.

Table 2:

serial number	Reaction time (h)	Uranium concentration (mg/L)	Uranium removal rate
				1	2	78	48％
2	5	37	75.3％
				3	24	7.2	95.2％

And (3) introducing 2300mL of uranium-containing wastewater for treatment for 28h in a 3 rd circulation manner, wherein the concentration of the uranium-containing wastewater is 150 mg/L. The initial pH value of the uranium-containing waste water is 7.45. The concentration of the uranium-bearing wastewater after a certain time is sampled and measured, and ICP is adopted for testing, and the test results are shown in Table 3.

Table 3:

serial number	Reaction time (h)	Uranium concentration (mg/L)	Uranium removal rate
				1	2	100.6	32.9％
2	17	29.4	80.4％
				3	28	2.6	93.8％

Example 2

After the end of the treatment in example 1, the dynamic reaction bed was emptied of uranium-containing wastewater.

And (3) taking water as an eluent, flushing the dynamic reaction bed at the flow rates of 150mL/min, 200mL/min, 250mL/min and 420mL/min in sequence, flushing 100mL each time, pumping air to empty the eluent after flushing is finished, flushing again, collecting 995mL of the eluent altogether, and finishing water washing and activating the dynamic reaction bed to obtain the activated sponge iron filter material.

And (3) introducing uranium-containing wastewater into the activated dynamic reaction bed for 3 times of circulating treatment, wherein the treatment method is carried out according to the method in the embodiment 1. The concentration of the uranium-bearing wastewater treated in each stage is tested after the circulating adsorption, and the test results are shown in table 4.

Table 4:

as can be seen from table 4, after the dynamic reaction bed is activated and reused, 3 cycles of uranium-containing wastewater treatment are performed, and after 24 hours of treatment, the removal rates are respectively 95.3%, 90.2% and 70%, which are slightly lower than the removal rate of the new material, as shown in fig. 1.

Example 3

After the uranium-containing wastewater treatment in experimental example 2 was completed, the uranium-containing wastewater in the dynamic reaction bed was drained.

300mL of 0.24mol/L diluted hydrochloric acid solution is prepared, the diluted hydrochloric acid solution is pumped into the dynamic reaction bed at the flow rate of 60mL/min to wash for 5min, leacheate is collected, and effluent contains black silt. And (4) completing acid washing and activating the dynamic reaction bed, namely completing the activation of the sponge iron filter material.

And (3) introducing uranium-containing wastewater into the activated dynamic reaction bed for 3 times of circulating treatment, wherein the treatment method is carried out according to the method in the embodiment 1. The concentration of the uranium-containing wastewater treated in each stage is tested after the circulating adsorption, and the test results are shown in table 5.

Table 5:

from experimental data, the removal rates after 24 hours of reaction in 3 cycles are 94.1%, 82.1% and 65.3%, respectively, which is slightly lower than the removal rate of the new material, as shown in fig. 1.

The experimental data show that the reuse effect can be achieved through water washing and acid washing, the processing time is prolonged, the uranium removal rate can reach more than 85% of that of a new material, the water consumption for water washing is large, the water consumption for acid washing is small, and the sponge iron filter material can be effectively reused and regenerated.

The invention has been described in detail with reference to specific embodiments and/or illustrative examples and the accompanying drawings, which, however, should not be construed as limiting the invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its embodiments without departing from the spirit and scope of the present invention, which fall within the scope of the present invention. The scope of the invention is defined by the appended claims.