Method for extracting high-purity scandium oxide based on silicon-based tributyl phosphate resin

Abstract

The invention provides a method for extracting high-purity scandium oxide based on silicon-based tributyl phosphate resin, and belongs to the technical field of purification. The method comprises the following steps: mixing the titanium white waste acid with silicon-based tributyl phosphate resin, adding a pre-prepared acid solution, communicating purified resin and enriched resin with the acid solution, enabling the resin to become poor resin after multiple times of drainage, after one round of adsorption is finished, reversely adding the silicon-based tributyl phosphate resin into an alkali solution, desorbing, and electrolyzing a desorption solution, thereby obtaining the titanium white waste acid. A high-purity scandium oxide compound is obtained; the silicon-based tributyl phosphate resin is added, and a large amount of scandium oxide can be selectively adsorbed by utilizing the high adsorbability of the resin, so that the scandium oxide is separated out, and impurities such as Fe, Si, Ni and Ca are preliminarily removed. The method comprises the following steps: adding an alkaline solution into enrichment resin for desorption to obtain a desorption solution containing high scandium oxide;

Description

Technical Field

[0001] The invention belongs to the technical field of purification of rare earth metal compounds and is a method for extracting high-purity scandium oxide, in particular to a method for extracting scandium oxide from titanium dioxide waste acid based on tributyl silicon phosphate resin. Background Art

[0002] Scandium oxide is abundant in rare earth elements and a component of the heavy rare earth group. Its exceptional chemical activity, along with its optical, electrical, magnetic, and nuclear properties, makes it useful in the manufacture of a variety of functional materials. It plays an indispensable role in the metallurgical casting industry, luminescent materials, permanent magnets, environmentally friendly materials, and other high-tech and cutting-edge scientific fields. However, with the advancement of cutting-edge technology, the purity requirements for scandium oxide are becoming increasingly stringent. Semiconductor chip targets require a purity level of 99.9995% (5N5) to ensure chip performance and reliability. However, China lacks key rare earth purification technologies, and the purity achieved cannot meet cutting-edge technological requirements, only industrial-grade requirements. In the original industry, the scandium oxide obtained by a single electrolysis often contains impurities, and a large amount of alkaline solution needs to be consumed during the precipitation process. Other precipitation methods are also likely to introduce other impurities, affecting the purity of scandium oxide. In addition, the solvent extraction method adopted on the market requires the separation of multiple elements one by one, and the entire process takes a long time. An average of 500 kg of rare earth acid requires 100 extraction tanks, which consumes a lot of manpower. The extracted materials cannot be purified multiple times and have a limited number of uses, which restricts the mass production of high-purity rare earths. However, in order to support and guide the development of high-end rare earth application industries, the country has increased financial support for the rare earth industry, which has enabled the industry to enter a period of rapid development. This has posed new challenges to the purification requirements of rare earth elements and their compounds. Summary of the Invention

[0003] The purpose of the present invention is to overcome the three major industry pain points of the scandium purification technology on the market, namely, substandard purity, high preparation cost, and long production cycle, and to solve the above-mentioned problems existing in the current technology. The adsorption extraction of scandium oxide is carried out on titanium dioxide waste acid, and the high selectivity of silicon-based tributyl phosphate resin is utilized to effectively remove impurities, and finally a high-purity scandium oxide compound with a purity of up to 5N grade (99.999%) with extremely low impurity content is obtained.

[0004] The technical solution of the present invention is: a method for extracting scandium oxide based on a novel silicon-based tributyl phosphate resin, the method comprising the following steps:

[0005] (1) First, silicon-based tributyl phosphate resin is loaded into a resin column, and titanium dioxide waste acid is passed through the resin column at a flow rate of 0 to 10 BV / h through a pressure pump, and the operating temperature is 285 to 305 K. After adsorption saturation, adsorption is stopped;

[0006] (2) For the resin after stopping adsorption in step (1), the residual titanium dioxide waste acid is washed away with ultrapure water, and the washing is stopped after the pH value of the outflowing washing liquid is in the range of 7 to 10;

[0007] (3) For the silicon-based tributyl phosphate extraction resin after washing in step (2), its resin column and the resin column of the enrichment resin are connected to the hydrochloric acid solution storage tank and connected, and desorbed with a hydrochloric acid solution with a pH value between 0.1 and 3.5, with a flow rate of 1 to 2 column bed volumes / hour and an adsorption temperature between 275K and 310K. The hydrochloric acid solution first slowly flows into the resin column of the silicon-based tributyl phosphate extraction resin, then flows into the resin column of the enrichment resin, and finally drains back to the storage tank. It is necessary to continuously add a hydrochloric acid solution with a concentration of 1 to 1.5 mol / L to adjust and ensure that the pH value in the tank remains stable; when the scandium oxide content in the acidic solution flowing out of the resin column is 20 mg / L, becoming a lean resin, desorption is stopped to obtain a primary desorption liquid; the lean resin is washed with ultrapure water, and the washing is stopped when the pH value of the effluent is between 5.5 and 7;

[0008] (4) loading the silyl tributyl phosphate enrichment resin into the resin column, injecting the primary desorption liquid into the resin column at a flow rate of 1 to 2 column bed volumes per hour, and stopping the adsorption when adsorption saturation is reached;

[0009] (5) For the resin after stopping adsorption in step (4), sodium hydroxide solution with a pH value of 8 to 11 is reversely added to the resin column for desorption, the desorption temperature is between 293 and 343K, and the flow rate is 1 to 2 column bed volumes / hour. When the scandium oxide content in the effluent of the silicon-based tributyl phosphate enriched resin column is less than 40 mg / L, the desorption is stopped to obtain a secondary desorption liquid. After the desorption is completed, the silicon-based tributyl phosphate enriched resin is washed with ultrapure water until the pH value of the effluent is 7 to 10;

[0010] (6) electrolyzing the secondary desorption liquid to obtain a high-purity scandium oxide compound;

[0011] The above method is a complete cycle operation.

[0012] Preferably, the silicon-based tributyl phosphate enrichment resin is a chelating resin having one of a hydroxyoxime group and an amidoxime group that selectively adsorbs scandium oxide.

[0013] Preferably, in step (3), the hydrochloric acid solution can also be prepared from sulfuric acid, nitric acid, formic acid, chloroacetic acid, phosphoric acid, glacial acetic acid, citric acid, or picric acid; the pH value of the acid solution is between 0.1 and 3.5, preferably between 0.1 and 3, and more preferably between 1 and 2; the operating temperature for the acid solution circulation adsorption and enrichment is 275K to 310K, preferably between 280K to 300K, and more preferably between 285K to 290K.

[0014] Preferably, in step (4), the silicon-based tributyl phosphate enrichment resin column is a single column, or multiple columns connected in series, preferably multiple columns connected in series; when multiple columns are connected in series, the concentration of scandium oxide contained in the outlet solution of each resin column is used to judge whether the resin column of that stage has reached adsorption saturation. When the inlet and outlet concentrations are the same, it is considered to have reached saturation; and when the adsorption of the first-stage resin column reaches saturation, the resin column is directly unloaded.

[0015] Preferably, in step (5), the sodium hydroxide solution can also be prepared from potassium hydroxide, ammonia water, and sodium carbonate solution; the concentration of the alkaline desorbent solution is 1N to 8N, preferably 2N to 6N, and more preferably 2.5N to 5N. The temperature for secondary desorption is 293 to 343K, preferably 313 to 333K.

[0016] The crude rare earth solution involved in the present invention contains other impurity elements such as vanadium, aluminum, iron, magnesium, calcium, tungsten and other common impurity elements after adsorption in step (1). Steps (3) and (5) are two different systems used in combination to purify scandium oxide, wherein step (3) is acid adsorption.

[0017] The technical solution provided by the present invention can reduce the scandium oxide content in the secondary desorption liquid to a minimum of 3 to 10 g / L, which is more than 10 times the scandium oxide extraction capacity of ordinary resins used in industry. In addition, the final desorption liquid is directly electrolyzed, eliminating the need for a second washing process with water, while also reducing product loss and improving electrolysis efficiency.

[0018] The present invention overcomes the shortcomings of the prior art. The silicon-based tributyl phosphate resin used has the advantages of high acid resistance and alkali resistance, can reduce resin loss, and save costs. At the same time, the resin also has the advantages of high desorption efficiency and good scandium oxide recovery rate. In addition, a circulating acid solution operation method is adopted to completely transfer the scandium oxide adsorbed on the adsorption resin to the enrichment resin. Finally, the resin is desorbed by a circulating alkaline solution, so that the obtained desorption liquid contains a higher amount of scandium oxide, thereby greatly improving the yield and efficiency.

[0019] The beneficial effects of the present invention are as follows: scandium oxide is extracted from a crude rare earth solution by using a novel silicon-based tributyl phosphate resin, thereby achieving separation of scandium oxide from other impurity elements in the rare earth solution, especially reducing the influence of vanadium and aluminum elements; the purity of the prepared high-purity scandium oxide is as high as 99.999%, which protects subsequent electrolysis from their influence, improves the purity of scandium oxide as a whole, and effectively reduces the content of other impurities during the electrolysis process; the resin, acidic solution, and desorbent are reusable, reducing overall costs, and providing technical support for the electrolysis of high-purity scandium oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a process series desorption flow chart of the present invention.

[0021] Figure 2 is the column elution curve for water adsorption. DETAILED DESCRIPTION

[0022] Example 1 Figure 1 As shown in the process series desorption flow chart of the present invention, the method for extracting scandium oxide from titanium dioxide waste acid with a novel silicon-based tributyl phosphate resin comprises the following steps:

[0023] (1) 500 ml of the novel tributyl silyl phosphate extraction resin and 500 ml of the tributyl silyl phosphate enrichment resin were loaded into two resin columns respectively and connected in series. The crude rare earth solution was passed through the tributyl silyl phosphate adsorption resin column at a flow rate of 5 column bed volumes / hour and a temperature of 300 K.

[0024] (2) washing the resin after adsorption in step (1) with ultrapure water at a rate of 2 column bed volumes / hour, and the washing temperature is 300K;

[0025] (3) 1.5 mol / L hydrochloric acid was injected into the resin column in step (2) at a rate of 1 column bed volume / hour at a temperature of 290 K. The operation was repeated. When the scandium oxide content in the acidic solution flowing out of the resin column was less than 20 mg / L and the resin became lean, the circulation was stopped. The resin in step (2) was washed again with ultrapure water. When the pH value of the washing solution at the outlet was 5.5-7, the washing was stopped. The metal ion concentrations in the crude rare earth solution were shown in Table 1 below. The metal ion concentrations in the acidic solution were shown in Table 2 below.

[0026] (4) For the desorption of the new silicon-based tributyl phosphate enrichment resin, 2 mol / L sodium hydroxide solution was used at a rate of 2 column bed volumes / hour, and the operating temperature was 300K. When the scandium oxide concentration in the outflowing alkaline solution was lower than 40 mg / L, the desorption was stopped. After the desorption was completed, the enrichment resin was washed with water. When the pH value of the outflowing solution was between 7 and 10, the desorption was stopped. At this time, the metal ion concentration in the alkaline solution was as shown in Table 3. The ion content of each concentration was very small and could be ignored.

[0027] Table 1 Metal ion concentration of titanium dioxide waste acid

[0028] element Dy V Ca Mg Cu Fe Al Zn W Content (ml / L) 246.23 117.24 8.46 61.74 1.64 11.01 25354 4.28 8.16

[0029] Table 2 Metal ion concentration in acidic solution

[0030] element Dy Mg Fe Al V W Concentration (mg / L) 121.78 24.54 5.54 261.65 55.42 20.94

[0031] Table 3 Metal ion concentration in alkaline solution

[0032] element Dy Mg Fe Al V W Concentration (mg / L) 117.45 2.49 3.98 6.01 7.86 4.32

[0033] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or simple replacements that are not conceived through creative work should be included in the protection scope of the present invention.

[0034] Figure 2 is the column elution curve for water adsorption.

Claims

1. A method for extracting high-purity scandium oxide based on silicon-based tributyl phosphate resin, characterized in that The following steps are included: (1) Mixed adsorption: First, the silicon-based tributyl phosphate purification resin and the titanium dioxide waste acid containing scandium oxide are sequentially loaded into the resin cylinder. When the concentrations of the inlet and outlet solutions are consistent, the silicon-based tributyl phosphate purification resin is basically saturated with adsorption; (2) Washing: Use ultrapure water to wash the extraction resin that adsorbs scandium oxide. Stop washing when the pH value of the outflowing washing liquid is in the range of 7 to 10. (3) Primary desorption: The acid solution is prepared in advance and injected into the storage tank, and then the resin column containing the silicon-based tributyl phosphate purification resin and the resin column containing the enrichment resin are connected to the acid solution storage tank and connected; During the process, a pressure pump is used to better control the speed at which the acidic solution flows into the resin column. The acidic solution will first slowly flow into the resin column of the silicon-based tributyl phosphate extraction resin, then into the resin column of the enrichment resin, and finally be drained back to the storage tank. After multiple cycles, when the resin becomes lean, that is, when the scandium oxide content in the acidic solution flowing out of the resin column is less than 20mg / L, the circulation is stopped; the lean resin is washed again with water, and when the pH value of the washing liquid at the outlet is in the range of 5.5-7, the next cycle of adsorption operation begins. (4) Secondary desorption: desorb the tributyl phosphate enrichment resin, that is, add a certain concentration of alkaline solution into the tributyl phosphate enrichment resin column in reverse at a certain flow rate to desorb. When the scandium oxide concentration in the outflowing alkaline solution is lower than 40 mg / L, the desorption is stopped to obtain a two-step desorption solution. After the desorption is completed, the enrichment resin is washed with water to make the pH value of the outflowing solution between 7 and 10. (5) Electrolysis: The two desorption solutions are electrolyzed to obtain scandium oxide compounds; The silicon-based tributyl phosphate extraction resin described in step (1) is a 95% epoxy-modified corrosion-resistant resin; the silicon-based tributyl phosphate enrichment resin described in step (3) includes silicon-based tributyl phosphate resin and silicon-based amidoxime resin.

2. The method for extracting high-purity scandium oxide based on silicon-based tributyl phosphate resin according to claim 1, characterized in that: In the step (1), when the silicon-based tributyl phosphate extraction resin absorbs scandium oxide from the titanium dioxide waste acid, the operating flow rate is between 0 and 10 BV / h.

3. The method for extracting high-purity scandium oxide based on silicon-based tributyl phosphate resin according to claim 1, characterized in that: In the step (1), when the silicon-based tributyl phosphate extraction resin absorbs scandium oxide from the titanium dioxide waste acid, the operating temperature is 285~305K.

4. The method for extracting high-purity scandium oxide based on silicon-based tributyl phosphate resin according to claim 1, characterized in that: In the step (3), the pH value in the tank is adjusted and ensured to remain stable by continuously adding an acid solution with a concentration of 1 to 1.5 mol / L.

5. The method for extracting high-purity scandium oxide based on silicon-based tributyl phosphate resin according to claim 1, characterized in that: In the step (3), the acid solution is prepared by selecting hydrochloric acid, sulfuric acid, nitric acid, formic acid, chloroacetic acid, phosphoric acid, glacial acetic acid, citric acid, and picric acid.

6. The method for extracting high-purity scandium oxide based on silicon-based tributyl phosphate resin according to claim 1, characterized in that: In the step (4), the alkaline solution is prepared by selecting potassium hydroxide, sodium hydroxide, ammonia water, and sodium carbonate solution.

Images