阅读说明：本技术 一种双磷酸萃取剂用于萃取分离锆铪的方法 (Method for extracting and separating zirconium and hafnium by using biphosphoric acid extracting agent ) 是由 崔玉 赵嘉琳 赵奕铭 于 2019-11-12 设计创作，主要内容包括：本发明公开了一种利用新型双磷酸萃取剂N,N—正辛胺二(亚甲基苯次磷酸)萃取分离锆铪的方法,萃取率远远超过常见的酸性有机磷萃取体系,主要解决了锆铪萃取率低、分离效果差的问题。N,N—正辛胺二(亚甲基苯次磷酸)在不同酸度下对锆铪均有很好的萃取效果,并优先萃取锆。通过反萃回收锆铪离子,反萃率高达99%以上,有机相可重复利用。本技术萃取率高、分离效果好、污染小、成本低,可用于锆铪分离的工业生产中。(The invention discloses a method for extracting and separating zirconium and hafnium by using a novel diphosphonic acid extractant N, N-N-octylamine di (methylene benzene hypophosphorous acid), wherein the extraction rate is far higher than that of a common acidic organophosphorus extraction system, and the problems of low extraction rate and poor separation effect of zirconium and hafnium are mainly solved. N, N-octylamine di (methylene benzene hypophosphorous acid) has good extraction effect on zirconium and hafnium under different acidity, and preferentially extracts zirconium. The zirconium hafnium ions are recovered by back extraction, the back extraction rate is up to more than 99 percent, and the organic phase can be recycled. The technology has high extraction rate, good separation effect, little pollution and low cost, and can be used in industrial production of zirconium and hafnium separation.)

1. A method for extracting and separating zirconium and hafnium by using a novel extracting agent N, N-N-octylamine di (methylene benzene hypophosphorous acid), which is characterized in that the extracting agent is N, N-N-octylamine di (methylene benzene hypophosphorous acid), and the method comprises the following steps:

(1) dissolving the extractant in an organic solvent to form an organic phase;

(2) adding an acidic solution into mother liquor containing zirconium and hafnium to dilute to form a water phase;

(3) mixing the organic phase and the water phase to extract the zirconium and the hafnium into the organic phase;

and (4) carrying out back extraction on the organic phase after extraction to obtain an aqueous solution containing zirconium hafnium ions.

2. The method for extracting and separating zirconium and hafnium by using diphosphonic acid extractant as claimed in claim 1, wherein in step (1), the organic phase diluent is chloroform, and the concentration of extractant is 0.001-1 mol/L.

3. The method for extracting and separating zirconium and hafnium by using diphosphonic acid extractant as claimed in claim 1, wherein in the step (2), the mother solution is diluted by hydrochloric acid, sulfuric acid and nitric acid solution, and the acidity of the aqueous phase is 0.01-6 mol/L.

4. The method for extracting and separating zirconium and hafnium by using diphosphonic acid extractant as claimed in claim 1, wherein in the step (3), the volume ratio of the organic phase to the aqueous phase is 5: 1-1: 5, the extraction temperature is 20-50 ℃, and the extraction time is 5-60 minutes.

5. The method for extracting and separating zirconium and hafnium by using diphosphonic acid extractant as claimed in claim 1, wherein in step (3), the organic phase stripping time is controlled to 5-60 minutes, the stripping solution is pure water solution, the process is carried out at normal temperature, and the stripped organic phase is recycled.

Technical Field

The invention belongs to the technical field of extraction and separation of zirconium and hafnium, and particularly relates to a method for extracting and separating zirconium and hafnium by using a novel dual-phosphoric acid extracting agent.

Background

With the excessive consumption of traditional fossil energy such as coal, oil, natural gas and the like and the increasingly obvious negative effects of burning fossil fuel on human living environment, nuclear energy becomes an indispensable novel alternative energy by virtue of various advantages such as environmental protection, economy, safety and the like, and is rapidly developed and matured in recent decades. Hafnium zirconium is two extremely important metal materials in the nuclear industry. Zirconium has a small thermal neutron absorption cross section (0.18 b), is corrosion resistant, is used for cladding and structural materials of a reactor, and is a first safety barrier for preventing nuclear fuel uranium from leaking. Hafnium has a large thermal neutron absorption cross section (120 b) and can absorb thermal neutrons of a nuclear reactor to control the reaction speed of the nuclear reactor. Nuclear grade zirconium requires less than 0.01% hafnium and less than 2% zirconium in nuclear grade hafnium. However, hafnium zirconium is associated in nature as an ore, and the hafnium content of zirconium is generally around 2%. The zirconium hafnium is in the same subgroup, and has close atomic configuration and physical and chemical properties, so that the zirconium hafnium is not easy to separate, and the extraction and separation of the zirconium hafnium have profound influence on the atomic energy industry. The existing zirconium hafnium separation methods can be divided into two categories of pyrogenic separation and wet separation, wherein the solvent extraction method has the characteristics of low cost, high yield, safe operation, simple equipment, thorough separation, continuous operation and the like, and becomes the mainstream of research.

The following three major zirconium-hafnium separation processes are widely used in mass production: MIBK-NH₄SCN method, TBP-HNO₃By the HCl method, TOA/N235-H₂SO₄The method is carried out. MIBK-NH₄The SCN system is the only process for preferentially extracting hafnium and is also the separation production path of zirconium and hafnium which is most applied. The method has high extraction efficiency, but hydrogen sulfide, hydrocyanic acid, mercaptan and the like can be generated from HSCN complex in industrial discharged sewage, and the waste gas contains toxic substances such as high-purity ammonia, cyanide, organic compounds and the like, thereby causing serious environmental pollution. TBP-HNO₃The HCl system has good separation effect and large extraction capacity, but the mixed acid system corrodes equipment and emulsification causes that continuous production cannot be carried out. The TOA method has the advantages of small pollution, low cost, difficult dissolution of an extracting agent in water and the like, but has the defects of low zirconium-hafnium extraction efficiency, poor separation effect and the like.

Disclosure of Invention

Although the above several industrially common processes are capable of separating hafnium zirconium, they have considerable disadvantages, which greatly limit their industrial application. Therefore, it is necessary to explore a new extraction and separation method of hafnium zirconium. The acidic organophosphorus extractant is widely applied to solution extraction, and the diphosphonic acid extractant can form a stable chelating structure with metal, so that the extraction effect is better without report. The novel diphosphonic acid extractant N, N-N-octylamine di (methylene benzene hypophosphorous acid) used in the method has strong extraction capacity to zirconium and hafnium from low acidity to high acidity, and has certain identification capacity to zirconium, so as to solve the problems of low zirconium and hafnium extraction rate, poor separation effect, environmental pollution, high cost and the like.

In order to solve the technical problems, the method adopts the following specific operation steps:

(1) dissolving the extractant in an organic solvent to form an organic phase;

(2) adding an acidic solution into mother liquor containing zirconium and hafnium to dilute to form a water phase;

(3) the organic phase and the aqueous phase are mixed to extract the hafnium zirconium into the organic phase. And (4) carrying out back extraction on the organic phase after extraction to obtain an aqueous solution containing zirconium hafnium ions.

As a further optimization scheme, in the step (1), the organic phase diluent is trichloromethane, and the concentration of the extracting agent is 0.001-1 mol/L.

As a further optimization scheme, in the step (2), the mother liquor is diluted by using hydrochloric acid, sulfuric acid and nitric acid solution, and the acidity of the water phase is 0.01-6 mol/L.

As a further optimization scheme, in the step (3), the volume ratio of the organic phase to the water phase is 5: 1-1: 5, the extraction temperature is 20-50 ℃, and the extraction time is 5-60 minutes.

As a further optimization scheme, in the step (3), the organic phase stripping time is controlled to be 5-60 minutes, the used stripping solution is a pure water solution and is carried out at normal temperature, and the stripped organic phase is recycled.

Compared with the prior art, the invention has the advantages and positive effects that:

the N, N-N-octylamine di (methylene benzene hypophosphorous acid) can form a chelate structure with zirconium and hafnium under different acidity, has good extraction performance on zirconium and hafnium, has extraction rate far higher than that of the acidic organophosphorus extractant used in the current industry, and improves the extraction rate on zirconium and hafnium by 7 and 13 times respectively under the same condition compared with di (2,4, 4-trimethylpentyl) hypophosphorous acid.

2. Has selectivity to zirconium and hafnium, preferentially extracts zirconium, and has a separation factor of 3.66.

3. The extraction separation method provided by the invention has good extraction effect on zirconium and hafnium under low acidity or high acidity, and the back extraction rate is more than 99%. The extractant is insoluble in water, the organic phase can be recycled through back extraction, all the adopted reagents are low in price and easy to obtain, the investment is small, and the cost is saved.

4. The method for separating zirconium and hafnium has the advantages of simple operation, low cost, high extraction rate and little pollution, and can be used for automatic control and large-scale production.

Detailed Description

After extraction and separation are finished, the concentration of metal ions in the water phase is measured by an inductively coupled plasma optical emission spectrometer (ICP-OES), the extraction rate (E) can more intuitively display the extraction capacity of N, N-N-octylamine bis (methylene benzene hypophosphorous acid) to zirconium and hafnium, the separation factor (β) is an important basis for showing the separation effect of zirconium and hafnium, and the separation factor can be calculated by the following formula:

wherein C is_orgAnd C_aqAnd refer to the organic and aqueous phase metal ion concentrations, respectively.

To better illustrate the invention and to facilitate the understanding of the technical solutions thereof, typical but non-limiting examples of the invention are as follows: