阅读说明：本技术 一种硝酸体系含铀废水的除铀方法 (Uranium removing method for uranium-containing wastewater in nitric acid system ) 是由 支梅峰 王皓 舒祖骏 赵凤岐 牛玉清 常喜信 周志全 于 2020-04-24 设计创作，主要内容包括：本发明涉及湿法冶金技术领域,具体公开了一种硝酸体系含铀废水的除铀方法,包括以下步骤：步骤一：配制特定混合试剂；步骤二：混合；步骤三：中和沉淀；步骤四：固液分离。本发明方法除铀效率高,工艺流程简单,实用性强,且不产生其他工艺废物,对水体无二次污染。(The invention relates to the technical field of hydrometallurgy, and particularly discloses a uranium removing method for uranium-containing wastewater in a nitric acid system, which comprises the following steps: the method comprises the following steps: preparing a specific mixed reagent; step two: mixing; step three: neutralizing and precipitating; step four: and (4) solid-liquid separation. The method has the advantages of high uranium removal efficiency, simple process flow, strong practicability, no generation of other process wastes and no secondary pollution to water.)

1. A uranium removing method for uranium-containing wastewater in a nitric acid system is characterized by comprising the following steps: the method comprises the following steps:

the method comprises the following steps: preparing specific mixed reagent

The raw materials of the specific mixed reagent are oxides, carbonates or nitrates of iron, magnesium and aluminum, and the solid raw materials are uniformly mixed to prepare the specific mixed reagent containing the elements of iron, magnesium and aluminum;

step two: mixing

Mixing a specific mixed reagent with uranium-containing wastewater in a nitric acid system to obtain a mixed solution;

step three: neutralizing the precipitate

Adding a neutralization precipitation reagent into the mixed solution until the pH value of the end point is 6-9, and then carrying out neutralization precipitation reaction to obtain neutralization precipitation slurry;

step four: solid-liquid separation

And filtering the neutralized and precipitated slurry to obtain precipitation mother liquor with the uranium concentration of less than 0.05mg/L, pH value of 6-9.

2. The uranium removing method for uranium-bearing wastewater in nitric acid system according to claim 1, wherein: in the first step, the usage amount of the raw materials satisfies the mass ratio relationship of iron, magnesium and aluminum in the prepared specific mixed reagent of (4-30): 2-8): 1-5.

3. The uranium removal method for uranium-bearing wastewater in a nitric acid system according to claim 2, wherein: in the second step, the adding amount of the specific mixed reagent is controlled, so that the liquid-solid ratio of the uranium-containing wastewater to the specific mixed reagent is 6-60L/kg.

4. The uranium removing method for uranium-bearing wastewater in nitric acid system according to claim 3, wherein: in the second step, mechanical stirring is adopted for mixing, the mixing temperature is 10-80 ℃, and the mixing time is 0.5-2 hours.

5. The uranium removing method for uranium-bearing wastewater in nitric acid system according to claim 4, wherein: in the third step, the neutralizing and precipitating reagent is one of ammonia water, sodium hydroxide and calcium hydroxide solution.

6. The uranium removing method for uranium-bearing wastewater in nitric acid system according to claim 5, wherein: in the third step, the ammonia water is industrial ammonia water containing 25-28% of ammonia, the sodium hydroxide is an industrial solid product, and the solid content of the calcium hydroxide solution is 15-25%.

7. The uranium removing method for uranium-bearing wastewater in nitric acid system according to claim 6, wherein: in the third step, the reaction time of the neutralization precipitation reaction is 0.5-4 h, and the reaction temperature is 10-90 ℃.

8. The uranium removal method for uranium-bearing wastewater in a nitric acid system according to claim 7, wherein: in the fourth step, a plate-and-frame filter pressing mode is adopted for filtering.

9. The uranium removal method for uranium-bearing wastewater in a nitric acid system according to claim 2, wherein: in the first step, all solid raw materials are uniformly mixed by a stirrer.

10. The uranium removing method for uranium-containing wastewater in a nitric acid system according to any one of claims 1 to 9, wherein: in the uranium-containing wastewater of the nitric acid system, the concentration of nitric acid is 0.2-4 mol/L, the concentration of uranium is 0.05-300 mg/L, and the mass concentration of metal impurity elements is 0.5-30 g/L.

Technical Field

The invention belongs to the technical field of hydrometallurgy, and particularly relates to a uranium removing method for uranium-containing wastewater in a nitric acid system.

Background

With the rapid development of nuclear energy in China, the scale of nuclear fuel circulation facilities in China is continuously enlarged, the generation amount of waste water is gradually increased, and the pressure of waste water treatment of enterprises is increased. Generally, the problem of environmental pollution caused by wastewater generated in the nuclear fuel circulation process is mainly caused by uranium. The uranium concentration of the discharged wastewater is less than 0.05mg/L according to the corresponding wastewater discharge standard issued by the state. How to economically and stably treat the wastewater and avoid the influence of uranium in the wastewater on the ecological environment and human health is always a difficult problem facing enterprises.

The methods for removing uranium reported at the present stage mainly include a chemical precipitation method, an evaporation concentration method, an adsorption method, an ion exchange method, a membrane treatment method, an electrolytic reduction method, and the like. The chemical precipitation method can be classified into a flocculation precipitation method and a chemical precipitation method, but when the existing flocculation precipitation method or the existing chemical precipitation method is used for treating the nitric acid system wastewater, the uranium concentration in the wastewater cannot reach or stably reaches the discharge standard, and a combined uranium removal process is formed by combining with a silica gel adsorption method and the like, for example, as described in patents CN106847357B and CN 108257706A; other methods also have the problems of long treatment flow or high cost, and part of methods cannot even meet the requirement of wastewater discharge, and usually need process combination, as described in patents CN106636690B, CN103193289B, CN109607849A, and the like.

In the production process of a uranium purification and conversion production line taking triuranium octoxide, sodium diuranate or ammonium diuranate and the like as raw materials, uranium-containing wastewater of a nitric acid system is generated. The existing uranium removal method for wastewater is only effective for a specific system, and a new development space is still provided for the uranium removal method for a nitric acid system, so that the uranium-containing wastewater treatment method for the nitric acid system, which is simple and convenient to operate, stable in treatment effect, high in uranium removal efficiency and capable of meeting the emission standard requirement of uranium concentration, has practical significance.

Disclosure of Invention

The invention aims to provide a uranium removing method for uranium-containing wastewater in a nitric acid system, so that the concentration of uranium after treatment can stably reach the standard.

The technical scheme of the invention is as follows:

a uranium removing method for uranium-containing wastewater in a nitric acid system comprises the following steps:

the method comprises the following steps: preparing specific mixed reagent

The raw materials of the specific mixed reagent are oxides, carbonates or nitrates of iron, magnesium and aluminum, and the solid raw materials are uniformly mixed to prepare the specific mixed reagent containing the elements of iron, magnesium and aluminum;

step two: mixing

Mixing a specific mixed reagent with uranium-containing wastewater in a nitric acid system to obtain a mixed solution;

step three: neutralizing the precipitate

Adding a neutralization precipitation reagent into the mixed solution until the pH value of the end point is 6-9, and then carrying out neutralization precipitation reaction to obtain neutralization precipitation slurry;

step four: solid-liquid separation

And filtering the neutralized and precipitated slurry to obtain precipitation mother liquor with the uranium concentration of less than 0.05mg/L, pH value of 6-9.

In the first step, the usage amount of the raw materials satisfies the mass ratio relationship of iron, magnesium and aluminum in the prepared specific mixed reagent of (4-30): 2-8): 1-5.

In the second step, the adding amount of the specific mixed reagent is controlled, so that the liquid-solid ratio of the uranium-containing wastewater to the specific mixed reagent is 6-60L/kg.

In the second step, mechanical stirring is adopted for mixing, the mixing temperature is 10-80 ℃, and the mixing time is 0.5-2 hours.

In the third step, the neutralizing and precipitating reagent is one of ammonia water, sodium hydroxide and calcium hydroxide solution.

In the third step, the ammonia water is industrial ammonia water containing 25-28% of ammonia, the sodium hydroxide is an industrial solid product, and the solid content of the calcium hydroxide solution is 15-25%;

in the third step, the reaction time of the neutralization precipitation reaction is 0.5-4 h, and the reaction temperature is 10-90 ℃.

In the fourth step, a plate-and-frame filter pressing mode is adopted for filtering.

In the first step, all solid raw materials are uniformly mixed by a stirrer.

In the uranium-containing wastewater of the nitric acid system, the concentration of nitric acid is 0.2-4 mol/L, the concentration of uranium is 0.05-300 mg/L, and the mass concentration of metal impurity elements is 0.5-30 g/L.

The invention has the following remarkable effects:

(1) the method has high uranium removal efficiency, and the uranium concentration in the wastewater can be stably reduced to below 0.05mg/L by one-step precipitation;

(2) the method has simple process flow and strong practicability, the uranium-containing wastewater of the prior nitric acid system generally needs neutralization precipitation and solid-liquid separation, and the method only needs to add a specific mixed reagent before the neutralization precipitation;

(3) the method does not generate other process wastes, and the materials used by the specific mixed reagent are inorganic materials, so that the method has no secondary pollution to the water body, and is economic and environment-friendly.

Drawings

FIG. 1 is a schematic process flow diagram.

Detailed Description

The invention is described in further detail below with reference to the figures and the embodiments.

In the uranium-removing method for the uranium-containing wastewater in the nitric acid system shown in fig. 1, in the uranium-containing wastewater in the nitric acid system, the concentration of nitric acid is 0.2-4 mol/L, the concentration of uranium is 0.05-300 mg/L, and the mass concentration of metal impurity elements is 0.5-30 g/L; the method comprises the following steps:

the method comprises the following steps: preparing specific mixed reagent

The raw materials of the specific mixed reagent are oxides or carbonates or nitrates of iron, magnesium and aluminum, and the solid raw materials are uniformly mixed by a stirrer to prepare the specific mixed reagent containing the elements of iron, magnesium and aluminum;

wherein the usage amount of the raw materials meets the mass proportion relationship of iron, magnesium and aluminum in the prepared specific mixed reagent of (4-30): 2-8): 1-5;

step two: mixing

Mixing a specific mixed reagent with uranium-containing wastewater of a nitric acid system by adopting mechanical stirring, wherein the mixing temperature is 10-80 ℃, and the mixing time is 0.5-2 h to obtain a mixed solution;

controlling the addition amount of the specific mixed reagent to ensure that the liquid-solid ratio of the uranium-containing wastewater to the specific mixed reagent is 6-60L/kg;

step three: neutralizing the precipitate

Adding a neutralization and precipitation reagent into the mixed solution until the pH value of the end point is 6-9, and then carrying out neutralization and precipitation reaction for 0.5-4 h at the reaction temperature of 10-90 ℃ to obtain neutralization and precipitation slurry;

the neutralization and precipitation reagent is one of ammonia water, sodium hydroxide and calcium hydroxide solution, wherein the ammonia water is industrial ammonia water containing 25-28% of ammonia, the sodium hydroxide is an industrial solid product, and the solid content of the calcium hydroxide solution is 15-25%;

step four: solid-liquid separation

And (3) carrying out plate-and-frame filter pressing on the neutralized and precipitated slurry to obtain a precipitation mother liquor with a uranium concentration of less than 0.05mg/L, pH value of 6-9.

Example one

In a certain uranium-containing wastewater, the concentration of uranium is 3mg/L, the concentration of nitric acid is 1.5mol/L, and the concentration of impurities is 8 g/L. The uranium removal method comprises the following steps:

firstly, preparing a specific mixed reagent, and mixing reagents of ferric oxide, magnesium oxide and aluminum oxide, wherein the ratio of the reagents to the reagents is 22:5: 4;

secondly, adding a specific mixed reagent into the uranium-containing wastewater for mixing, wherein the adding amount is carried out according to the liquid-solid ratio of 32:1(L/kg), and carrying out mixing reaction for 1h at the mixing temperature of 55 ℃;

then adding ammonia water as a neutralization and precipitation reagent into the mixed wastewater, wherein the concentration of the ammonia water is 20%, the end point pH value is controlled to be 7.3, the reaction temperature is 44 ℃, and the reaction time is 2 hours;

and finally, carrying out plate-and-frame filter pressing on the precipitation slurry, wherein the uranium concentration in the precipitation mother liquor is 0.027 mg/L.

Example two

In a certain uranium-containing wastewater, the concentration of uranium is 0.2mg/L, the concentration of nitric acid is 0.5mol/L, and the concentration of impurities is 3 g/L. The uranium removal method comprises the following steps:

firstly, preparing a specific mixed reagent, and mixing the reagents of ferric nitrate, magnesium nitrate and aluminum nitrate, wherein the ratio of the three reagents is 17:12: 8.

Secondly, adding a specific mixed reagent into the uranium-containing wastewater for mixing, wherein the adding amount is carried out according to the liquid-solid ratio of 27:1(L/kg), and carrying out mixing reaction for 1h at the mixing temperature of 25 ℃;

then adding a neutralization and precipitation reagent calcium hydroxide solution into the mixed wastewater, wherein the concentration is 18 percent, the end point pH value is controlled to be 7.5, the reaction temperature is 35 ℃, and the reaction time is 4 hours;

and finally, carrying out plate-and-frame filter pressing on the precipitation slurry, wherein the uranium concentration in the precipitation mother liquor is 0.028 mg/L.

Example three

In certain uranium-containing wastewater, the concentration of uranium is 200mg/L, the concentration of nitric acid is 2.5mol/L, and the concentration of impurities is 25 g/L. The uranium removal method comprises the following steps:

firstly, preparing a specific mixed reagent, and mixing reagents of iron carbonate, magnesium carbonate and aluminum carbonate, wherein the ratio of the reagents of iron carbonate, magnesium carbonate and aluminum carbonate is 42:42: 17;

secondly, adding a specific mixed reagent into the uranium-containing wastewater for mixing, wherein the adding amount is carried out according to the liquid-solid ratio of 10:1(L/kg), and the mixing reaction is carried out for 1.5h at the mixing temperature of 35 ℃;

then adding ammonia water as a neutralization and precipitation reagent into the mixed wastewater, wherein the concentration of the ammonia water is 20%, the end point pH value is controlled to be 8.3, the reaction temperature is 65 ℃, and the reaction time is 2.5 hours;

and finally, carrying out plate-and-frame filter pressing on the precipitation slurry, wherein the concentration of uranium in the precipitation mother liquor is 0.031 mg/L.

Example four

In a certain uranium-containing wastewater, the concentration of uranium is 12mg/L, the concentration of nitric acid is 3.5mol/L, and the concentration of impurities is 10 g/L. The uranium removal method comprises the following steps:

firstly, preparing a specific mixed reagent, and mixing reagents of ferric nitrate, magnesium carbonate and alumina, wherein the ratio of the reagents to the reagents is 43:24: 4;

secondly, adding a specific mixed reagent into the uranium-containing wastewater for mixing, wherein the adding amount is carried out according to a liquid-solid ratio of 15:1(L/kg), and carrying out mixing reaction for 2h at the mixing temperature of 45 ℃;

then adding a neutralization and precipitation reagent sodium hydroxide solid into the mixed wastewater, controlling the end point pH value to be 7.6, controlling the reaction temperature to be 57 ℃, and controlling the reaction time to be 3 h;

and finally, carrying out plate-and-frame filter pressing on the precipitation slurry, wherein the uranium concentration in the precipitation mother liquor is 0.024 mg/L.

Example five

In a certain uranium-containing wastewater, the concentration of uranium is 0.8mg/L, the concentration of nitric acid is 1.0mol/L, and the concentration of impurities is 5 g/L. The uranium removal method comprises the following steps:

firstly, preparing a specific mixed reagent, and mixing reagents of ferric oxide, magnesium carbonate and aluminum oxide, wherein the ratio of the reagents to the reagents is 7:12: 2;

secondly, adding a specific mixed reagent into the uranium-containing wastewater for mixing, wherein the adding amount is carried out according to a liquid-solid ratio of 24:1(L/kg), and carrying out mixed reaction for 2.5h at the mixing temperature of 40 ℃;

then adding a neutralization and precipitation reagent sodium hydroxide solid into the mixed wastewater, controlling the end point pH value to be 7.5, controlling the reaction temperature to be 45 ℃, and controlling the reaction time to be 3 h;

and finally, carrying out plate-and-frame filter pressing on the precipitation slurry, wherein the uranium concentration in the precipitation mother liquor is 0.019 mg/L.

Example six

In certain uranium-containing wastewater, the concentration of uranium is 50mg/L, the concentration of nitric acid is 2.0mol/L, and the concentration of impurities is 15 g/L. The uranium removal method comprises the following steps:

firstly, preparing a specific mixed reagent, and mixing reagents of iron carbonate, magnesium oxide and aluminum oxide, wherein the ratio of the reagents to the reagents is 37:10: 7;

secondly, adding a specific mixed reagent into the uranium-containing wastewater for mixing, wherein the adding amount is carried out according to a liquid-solid ratio of 20:1(L/kg), and carrying out mixing reaction for 2h at the mixing temperature of 35 ℃;

then adding ammonia water as a neutralization and precipitation reagent into the mixed wastewater, wherein the concentration of the ammonia water is 25%, the end point pH value is controlled to be 7.9, the reaction temperature is 70 ℃, and the reaction time is 2 hours;

and finally, carrying out plate-and-frame filter pressing on the precipitation slurry, wherein the concentration of uranium in the precipitation mother liquor is 0.023 mg/L.